Colored adhesive tape

Abstract

To provide a colored adhesive tape with a more uniform surface and stable gloss value. [Solution] The colored adhesive tape 1 is a colored adhesive tape in which a release film 6, an adhesive layer 5, a colored layer 4, a resin film layer 3, and a matte layer 2 are laminated in this order, the matte layer 2 mainly consists of a polyester resin, isocyanate, and a matting agent, the matting agent contains silica, and is a layer with a thickness of 0.5 μm to 3 μm, and the colored layer 4 is a layer mainly consisting of a resin, isocyanate, and a pigment containing carbon black.

Description

Technical Field

[0001] The present invention relates to a colored adhesive tape.

Background Art

[0002] Conventionally, colored films and colored adhesive tapes have been used in various industrial fields for purposes such as decoration, display, concealment, reflection, and light shielding. Among them, in personal computers, digital video cameras, and further in portable electronic terminals such as electronic notebooks, mobile phones, PHS (Personal Handyphone System), smartphones, game devices, and e-books, in fields where there is a particularly high demand for miniaturization and thinning, while fixing and protecting components, at the same time, by combining the light shielding effect by black coloring, the improvement of brightness by white coloring, hiding the appearance defects (non-uniformity, dot defects, etc.) of components and improving the appearance, etc., reduction of the number of components used is achieved, and thus various colored adhesive tapes are used. Also, in portable electronic terminals, an adhesive sheet may be used for the purpose of protecting a graphite sheet installed for heat dissipation purposes (for example, see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Incidentally, the adhesive sheet described in Patent Document 1 has a matte layer as the outermost layer and has a laminated structure of "matte layer / black colored layer / PET film / adhesive layer / release film". In an adhesive sheet having such a laminated structure of "matte layer / black colored layer / PET film / adhesive layer / release film", the matte layer is formed by applying a resin or the like that becomes the matte layer by performing gravure printing on the black colored layer. Therefore, when forming the matte layer, the surface of the black colored layer is roughened by the solvent, which makes it difficult to obtain a matte layer with a uniform surface. As a result, the gloss value of the matte layer becomes unstable.

[0005] This invention was made in view of the above-mentioned points, and aims to provide a colored adhesive tape that has a more uniform surface and a stable gloss value. [Means for solving the problem]

[0006] According to one aspect of the present invention, a colored adhesive tape is provided in which a release film, an adhesive layer, a colored layer, a resin film layer, and a matte layer are laminated in this order, wherein the matte layer mainly consists of a polyester resin, an isocyanate, and a matting agent, the matting agent contains silica, and the layer has a thickness of 0.5 μm or more and 3 μm or less, and the colored layer is a layer mainly consisting of a resin, an isocyanate, and a pigment containing carbon black. [Effects of the Invention]

[0007] According to one aspect of the present invention, a colored adhesive tape with a more uniform surface and stable gloss value can be obtained. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic cross-sectional view showing an example of a colored adhesive tape according to one embodiment of the present invention. [Figure 2] This is a schematic cross-sectional view showing an example of a case in which a colored adhesive tape according to one embodiment of the present invention is applied to a heat dissipation sheet or a magnetic sheet. [Modes for carrying out the invention]

[0009] Next, one embodiment of the present invention will be described below with reference to the drawings. Here, the drawings are schematic, and the relationship between thickness and planar dimensions, the ratio of the thickness of each layer, etc., may differ from reality. Furthermore, the embodiments shown below illustrate configurations for realizing the technical concept of the present invention, and the technical concept of the present invention is not limited to the materials, shapes, structures, etc. of the components described below. The technical concept of the present invention can be modified in various ways within the technical scope defined by the claims described in the patent claims.

[0010] (Composition of colored adhesive tape) Figure 1 is a schematic cross-sectional view showing a colored adhesive tape 1 according to one embodiment of the present invention. As shown in Figure 1, the colored adhesive tape 1 comprises a matte layer 2, a resin film layer 3, a colored layer 4, an adhesive layer 5, and a release film 6, and the colored adhesive tape 1 is formed by laminating these layers in order from the release film 6 side.

[0011] (Matte finish) The matte layer 2 is a layer mainly composed of a polyester resin, isocyanate, and a matting agent, with silica included as the matting agent. As the isocyanate, an aliphatic isocyanate such as HDI (hexamethylene diisocyanate) can be used. By including isocyanate in the matte layer 2, the adhesion to the resin film layer 3 as the substrate can be improved. From the viewpoint of obtaining a sufficient matte finish, the thickness of the matte layer 2 is preferably 0.5 μm or more. There is no upper limit to the thickness of the matte layer 2, but since a sufficient matte finish can be obtained with 3 μm, it is preferable that it be 3 μm or less. In this specification, a component that accounts for 50% or more by weight of the components in a layer is referred to as the main component, and "mainly composed of polyester resin, isocyanate, and matting agent" means that the total content of polyester resin, isocyanate, and matting agent exceeds 50% by weight of the components in the layer.

[0012] The matte layer 2 may or may not be colored. Coloring the matte layer 2 can improve the aesthetic appeal of the colored adhesive tape 1. When coloring the matte layer 2, for example, a pigment can be mixed into a paint for forming the matte layer 2, which mainly consists of a polyester resin, isocyanate, and a matting agent. Barium sulfate, for example, is sometimes used as a matting agent. However, if barium sulfate alone is added to the paint for forming the matte layer 2 as a matting agent, it is difficult to achieve a matte finish when the matte layer 2 is directly coated onto the resin film layer 3 made of PET resin, as described later. Furthermore, barium sulfate has a high specific gravity, is prone to precipitation, is relatively difficult to coat, and has small particle size, so a large amount of barium sulfate needs to be added to achieve a matte finish. In this embodiment, silica, which has a relatively low specific gravity and relatively large particle size, is used as a matting agent, so a sufficient matte finish can be achieved with a smaller amount of additive.

[0013] Preferably, the matte layer 2 has a 60° gloss value of 3 or less on the side opposite to the resin film layer 3. A surface with such a limited gloss value may be an alcohol-resistant surface. "Alcohol-resistant" means a surface in which changes in appearance (e.g., changes in gloss value, color, or light-shielding properties) are suppressed when exposed to alcohol (e.g., ethanol). This allows the surface of the colored adhesive tape 1, that is, the side of the matte layer 2 opposite to the resin film layer 3, to be wiped clean with alcohol without concern for reducing its aesthetic appeal. Therefore, stain resistance and aesthetic appeal can be ensured.

[0014] Furthermore, from the viewpoint of providing stain resistance to the colored adhesive tape 1, it is preferable that the water contact angle of the matte layer 2 on the side opposite to the resin film layer 3 is 80° or greater. The water contact angle can be measured using a commercially available contact angle measuring device in accordance with JIS R 3257:1999. For example, it can be measured under the following conditions. Water contact angle measurement conditions Measuring device: Contact angle measuring device FACE CA-X type (manufactured by Kyowa Kaimen Kagaku Co., Ltd.) Measurement environment: 23°C, 50%RH Liquid used for measurement: Distilled water Measurement time: 1500ms after droplet deposition

[0015] (Resin film layer) The resin film layer 3 is a layer used as a base material and is not particularly limited, but is formed from, for example, PET (polyethylene terephthalate) resin, PI (polyimide) resin, etc. If the thickness of the resin film layer 3 is 1 μm or more, the lamination of the colored layer and the matte layer can be performed well. If the thickness is 3 μm or less, the colored adhesive tape 1 will have sufficient flexibility, allowing for fine processing during use. The width of the resin film layer 3 is not limited, but for example, it has a width of 1050 mm.

[0016] (colored layer) The colored layer 4 is a black colored layer, mainly composed of a resin, an isocyanate, and a pigment containing carbon black. A polyester resin or an acrylic resin is preferred as the resin. As the isocyanate, an aliphatic isocyanate such as HDI (hexamethylene diisocyanate) can be used. Including an isocyanate in the colored layer 4 improves adhesion to the resin film layer 3. The colored layer 4 contains carbon black as a known coloring agent. Other coloring agents may be included for color matching purposes. Furthermore, "primarily composed of resin, isocyanate, and carbon black pigment" means that the total content of resin, isocyanate, and carbon black pigment exceeds 50% by weight of the components in the layer. From the perspective of ensuring sufficient concealment, the coloring layer 4 preferably has a thickness of 2 μm or more and 4 μm or less. When the thickness of the coloring layer 4 is 4 μm or more, the degree of change in concealment due to the thickness is relatively small, and the change in concealment obtained with respect to the increase in the thickness of the coloring layer 4 is small. Therefore, by setting the thickness of the coloring layer 4 to 2 μm or more and 4 μm or less, sufficient concealment can be obtained while suppressing the increase in the thickness of the coloring layer 4.

[0017] (Adhesive layer) The adhesive that constitutes the adhesive layer 5 is not particularly limited. For example, acrylic adhesives, urethane adhesives, synthetic rubber adhesives, polyester adhesives, silicone adhesives, etc. can be mentioned. Among them, from the perspective of being easy to adjust the molecular weight, crosslinking degree, etc., and being excellent in heat resistance, weather resistance, cost, etc., an acrylic adhesive containing a (meth)acrylic polymer is preferable. The above (meth)acrylic polymer is a polymer containing a structural unit derived from a (meth)acrylic monomer.

[0018] The above (meth)acrylic monomer is not particularly limited. For example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, tertiary butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, 2-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, lauryl (meth)acrylate, isomyristyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, etc. can be mentioned. These (meth)acrylic monomers may be used alone or in combination of two or more.

[0019] The above (meth)acrylic polymer preferably further contains a structure derived from a monomer containing a crosslinkable functional group. Because the above (meth)acrylic polymer contains a structure derived from the above crosslinkable functional group-containing monomer, the cohesive force of the adhesive layer 5 can be adjusted by crosslinking the crosslinkable functional group, thereby improving heat resistance. The above crosslinkable functional group may or may not be crosslinked, but it is more preferable that it be crosslinked. However, even if the structure remains uncrosslinked, the cohesive force of the adhesive layer 5 will increase due to the interaction between the functional groups.

[0020] Examples of the above-mentioned crosslinkable functional group-containing monomers include monomers containing carboxyl groups, hydroxyl groups, epoxy groups, double bonds, triple bonds, amino groups, amide groups, nitrile groups, and the like. These crosslinkable functional group-containing monomers may be used individually or in combination of two or more. Among these, at least one selected from the group consisting of carboxyl group-containing monomers and hydroxyl group-containing monomers is preferred. Hydroxyl group-containing monomers are more preferred because the heat resistance of the adhesive layer 5 can be easily adjusted by crosslinking with an isocyanate-based crosslinking agent. Furthermore, the above-mentioned monomer containing a crosslinkable functional group may also contain alkyl groups, ether groups, carbonyl groups, ester groups, carbonate groups, amide groups, urethane groups, and the like.

[0021] Examples of carboxyl group-containing monomers include (meth)acrylic acid-based monomers such as (meth)acrylic acid. Examples of hydroxyl group-containing monomers include 4-hydroxybutyl (meth)acrylate and 2-hydroxyethyl (meth)acrylate. Examples of epoxy group-containing monomers include glycidyl (meth)acrylate. Examples of double bond-containing monomers include allyl (meth)acrylate and hexanediol di(meth)acrylate. Examples of triple bond-containing monomers include propargyl (meth)acrylate. Examples of amide group-containing monomers include (meth)acrylamide.

[0022] The content of the structure derived from the monomer having the crosslinkable functional group in the above (meth)acrylic polymer is not particularly limited, but from the viewpoint of adjusting the adhesive strength and heat resistance of the adhesive layer 5, the preferred lower limit of the content of the above constituent unit is 0.05% by weight, and the preferred upper limit is 30% by weight. The more preferred lower limit of the content of the above constituent unit is 0.1% by weight, and the more preferred upper limit is 25% by weight. Furthermore, the content of the structure derived from the hydroxyl group-containing monomer in the (meth)acrylic polymer is not particularly limited, but from the viewpoint of adjusting the adhesive strength and heat resistance of the adhesive layer 5, the preferred lower limit of the content of the constituent units is 0.05% by weight, and the preferred upper limit is 5% by weight. The more preferred lower limit of the content of the constituent units is 0.08% by weight, and the more preferred upper limit is 1% by weight.

[0023] The (meth)acrylic polymer preferably contains structural units derived from monomers containing bio-derived carbon. By including structural units derived from monomers containing bio-derived carbon in the (meth)acrylic polymer, the content of bio-derived carbon in the adhesive layer 5 increases, and the environmental impact of the resulting adhesive tape can be further reduced. Furthermore, in this specification, "containing bio-derived carbon" means that the bio-based carbon content of the compound, as measured by ASTM D6866-22, is 1% or more. To obtain the above (meth)acrylic polymer, a monomer mixture containing the above (meth)acrylic monomer and the above crosslinkable functional group-containing monomer can be copolymerized by radical reaction in the presence of a polymerization initiator. Conventional known methods can be used for radical reaction of the above monomer mixture, i.e., polymerization methods, such as solution polymerization (boiling point polymerization or constant temperature polymerization), emulsion polymerization, suspension polymerization, and bulk polymerization.

[0024] The weight-average molecular weight (Mw) of the above (meth)acrylic polymer is not particularly limited, but a preferred upper limit is 2 million. If the above weight-average molecular weight (Mw) is 2 million or less, the initial adhesion to the substrate will be good even if the adhesive layer 5 is thin. A more preferred upper limit for the above weight-average molecular weight (Mw) is 1.5 million, and an even more preferred upper limit is 1.3 million. The lower limit of the weight-average molecular weight (Mw) is not particularly limited, but from the viewpoint of the adhesive strength and shape retention of the adhesive layer 5, a preferred lower limit is 400,000, and a more preferred lower limit is 500,000. The weight-average molecular weight of (meth)acrylic polymers can be determined, for example, by GPC (Gel Permeation Chromatography) on a standard polystyrene basis. More specifically, for example, it can be measured using a Water 2690 Separations Module as the measuring instrument, a Showa Denko GPC KF-806L column, and ethyl acetate as the solvent, with a sample flow rate of 1 mL / min and a column temperature of 40°C.

[0025] The adhesive layer 5 described above may contain a tackifying resin. Examples of the tackifying resins mentioned above include rosin ester resins, hydrogenated rosin resins, terpene resins, terpene phenol resins, coumarone indene resins, alicyclic saturated hydrocarbon resins, C5 petroleum resins, C9 petroleum resins, and C5-C9 copolymer petroleum resins. These tackifying resins may be used individually or in combination of two or more types. The content of the tackifying resin is not particularly limited, but from the viewpoint of ensuring good initial adhesion to the substrate even when the adhesive layer 5 is thin, and exhibiting sufficient adhesive strength, the preferred upper limit is 50 parts by weight, the preferred lower limit is 10 parts by weight, the more preferred upper limit is 35 parts by weight, and the more preferred lower limit is 20 parts by weight, relative to 100 parts by weight of the resin (e.g., (meth)acrylic polymer) that is the main component of the adhesive layer 5.

[0026] The adhesive layer 5 may be crosslinked with a crosslinking agent. The crosslinking agent is not particularly limited and is appropriately selected according to the adhesive that constitutes the adhesive layer 5. For example, if the adhesive that constitutes the adhesive layer 5 is an acrylic adhesive, examples of crosslinking agents include isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, and metal chelate crosslinking agents. Among these, isocyanate crosslinking agents, aziridine crosslinking agents, and epoxy crosslinking agents are preferred, with isocyanate crosslinking agents being preferred, as they result in the adhesive tape having superior adhesion to the adherend. These may be used alone or in combination of two or more. Examples of commercially available isocyanate crosslinking agents include Coronate HX (manufactured by Nippon Polyurethane Co., Ltd.) and Takenate D-101E (manufactured by Mitsui Chemicals, Inc.). Examples of commercially available epoxy crosslinking agents include Tetrad-C and Tetrad-X (manufactured by Mitsubishi Gas Chemical Co., Ltd.). Examples of commercially available metal chelate crosslinking agents include Aluminum Chelate A (manufactured by Kawaken Fine Chemical Co., Ltd.). The crosslinking agent content is not particularly limited, but a preferred lower limit is 0.1 parts by weight, a preferred upper limit is 5 parts by weight, a more preferred lower limit is 0.3 parts by weight, and a more preferred upper limit is 3 parts by weight per 100 parts by weight of adhesive solids.

[0027] The adhesive layer 5 described above may further contain known additives such as inorganic fillers like fumed silica, colorants such as pigments, plasticizers, resins, surfactants, waxes, and fine particle fillers. These additives may be used individually or in combination of two or more. The gel fraction of the adhesive layer 5 is not particularly limited, but a preferred lower limit is 10% by weight and a preferred upper limit is 70% by weight. If the gel fraction is 10% by weight or more, the heat resistance of the adhesive layer 5 is improved. If the gel fraction is 70% by weight or less, the adhesive layer 5 will exhibit sufficient adhesive strength even if it is thin. A more preferred lower limit for the gel fraction is 15% by weight, a more preferred upper limit is 65% by weight, an even more preferred lower limit is 20% by weight, and an even more preferred upper limit is 60% by weight.

[0028] The gel fraction of the adhesive layer 5 can be measured by the following method. 0.1 g of only the adhesive layer (adhesive composition) is taken from the colored adhesive tape and immersed in 50 mL of ethyl acetate. The mixture is shaken in a shaker at 23°C and 200 rpm for 24 hours. After shaking, the ethyl acetate and the adhesive composition that has absorbed and swollen with ethyl acetate are separated using a metal mesh (mesh size #200). The separated adhesive composition is dried at 110°C for 1 hour. The weight of the adhesive composition including the metal mesh after drying is measured, and the gel fraction of the adhesive layer is calculated using the following formula (1). Gel fraction (weight %) = 100 × (W1 - W2) / W0 ……(1) (W0: initial weight of adhesive composition, W1: weight of adhesive composition including metal mesh after drying, W2: initial weight of metal mesh)

[0029] However, if the adhesive layer does not dissolve completely in ethyl acetate, use a solvent such as toluene, hexane, or water instead. Specifically, if the adhesive layer contains, for example, a styrene-based elastomer, use toluene or hexane; if it contains polyvinyl alcohol, use 90°C hot water. The glass transition temperature (Tg) of the adhesive layer 5 is not particularly limited, but from the viewpoint of providing good adhesion and heat resistance even with a thin adhesive layer 5, a preferred lower limit is -70°C and a preferred upper limit is 25°C. A more preferred lower limit for the glass transition temperature (Tg) is -65°C and a more preferred upper limit is 15°C.

[0030] The glass transition temperature (Tg) of the adhesive layer 5 can be determined, for example, by measuring the storage modulus G' and loss modulus G'' at each temperature using the polymer dynamic viscoelasticity measuring device "itkDVA-200" (manufactured by IT Measurement Control Co., Ltd.) under the following conditions, calculating tanδ at each temperature, and determining the temperature at which tanδ takes its peak value as the glass transition temperature (Tg). Measurement mode: Shear Heating rate: 5°C / min Measurement temperature range: -30℃ to 150℃ Setting distortion: 0.1% Frequency: 1Hz

[0031] The thickness of the adhesive layer 5 is not particularly limited, but a preferred lower limit is 1 μm and a preferred upper limit is 4 μm. If the thickness of the adhesive layer 5 is less than 1 μm, the adhesiveness of the adhesive layer 5 will decrease and it may peel off from the adherend. If the thickness of the adhesive layer 5 exceeds 4 μm, the colored adhesive tape 1 will become thick and may not be suitable for use in portable electronic devices. A more preferred lower limit for the above thickness is 1.5 μm and a more preferred upper limit is 3.5 μm.

[0032] (Release film) The release film 6 is intended to protect the adhesive layer 5 until use, and its material is not particularly limited. The side of the release film 6 that contacts the adhesive layer 5 is a surface that has been treated with a release agent, and is made of, for example, a PET film coated with a silicone release agent. Furthermore, it is preferable that the average height Rc of the roughness curve elements on the side of the release film 6 opposite to the adhesive layer 5 is greater than 500 nm. A roughness curve element average height Rc greater than 500 nm reduces the frictional force with the roll when the colored adhesive tape 1 is transported, thereby suppressing meandering and wrinkle formation.

[0033] (Colored adhesive tape) The total film thickness of the colored adhesive tape 1 is set to 4.5 μm or more to ensure the necessary film thickness for each constituent layer to perform its function. Preferably, the total film thickness of the colored adhesive tape 1 is 13 μm or less, and more preferably 10 μm or less. This allows for precise adhesion of fine components. The total film thickness of the colored adhesive tape 1 as used herein refers to the total thickness of the laminate 1' consisting of the adhesive layer 5, the colored layer 4, the resin film layer 3, and the matte layer 2, excluding the release film 6.

[0034] From the viewpoint of obtaining sufficient light-shielding properties and masking (concealing) properties of the adherend, it is preferable that the light transmittance of the laminate 1' consisting of the matte layer 2, resin film layer 3, colored layer 4, and adhesive layer 5, excluding the release film 6, is 5% or less. Such a colored adhesive tape 1 can appropriately reflect the color of the adherend (e.g., graphite sheet) and impart the desired color, texture, and design. Because the colored adhesive tape 1 having such a configuration is extremely thin yet has good heat resistance, it can be used particularly suitably as a surface protection tape by, for example, as shown in Figure 2, attaching the adhesive layer 5 side of the colored adhesive tape 1' with the release film 6 removed to the surface of a heat dissipation sheet or magnetic sheet 10 that is attached to an electronic component that generates heat during use.

[0035] (Method of manufacturing colored adhesive tape) The method for manufacturing the colored adhesive tape 1 is not particularly limited, and examples include the following methods. First, a colored layer 4 is formed on one side of the resin film layer 3. For example, a colored layer paint containing carbon black is applied to one side of the resin film layer 3 by gravure printing or the like to form the colored layer 4. Next, a matte coating is applied to the other surface of the resin film layer 3 by gravure printing or the like to form a matte layer 2.

[0036] Next, an adhesive layer 5 is formed on the release-treated surface of the release film 6 by a casting method or the like. Examples of casting methods include applying a resin solution to form the adhesive layer 5 using methods such as gravure printing or roll coating, followed by heat drying. Next, the side of the colored layer 4 opposite to the resin film layer 3 and the side of the adhesive layer 5 opposite to the release film 6 are bonded together. This forms a colored adhesive tape 1 in which a release film 6, an adhesive layer 5, a colored layer 4, a resin film layer 3, and a matte layer 2 are laminated in this order.

[0037] (Effects of the colored adhesive tape according to this embodiment) The colored adhesive tape 1 has a matte layer 2 formed on one side of the resin film layer 3 and a colored layer 4 formed on the other side. Therefore, it is possible to avoid the surface of the colored adhesive tape 1, that is, the side of the matte layer 2 opposite to the resin film layer 3, becoming an uneven surface, and to obtain a colored adhesive tape 1 with a uniform surface. In other words, if the colored adhesive tape were formed with a laminated structure of "matte layer 2 / colored layer 4 / resin film layer 3 / adhesive layer 5 / release film 6", when the colored layer 4 is formed on the resin film layer 3 and then the paint for forming the matte layer 2 is applied on the colored layer 4 by gravure printing, the surface of the colored layer 4 may be roughened by the solvent contained in the paint for forming the matte layer 2, and as a result, the surface of the matte layer 2 formed on the colored layer 4 may not be uniform or the gloss value may be unstable. In contrast, in this embodiment, the colored adhesive tape 1 is configured with the layers laminated in the order of "matte layer 2 / resin film layer 3 / colored layer 4 / adhesive layer 5 / release film 6". Therefore, one side of the matte layer 2 becomes the surface of the colored adhesive tape 1, and the matte layer 2 is formed on top of the resin film layer 3. The surface of the resin film layer 3 is flat, and there is little possibility that the surface of the resin film layer 3 will be roughened when the matte layer 2 is formed on its surface. Therefore, the surface of the matte layer 2 formed on the surface of the resin film layer 3 will not become uneven due to the surface shape of the resin film layer 3, and as a result, a colored adhesive tape with a uniform surface on the matte layer 2 side can be obtained.

[0038] Another method to prevent surface unevenness of colored adhesive tape is to add a matting agent to the colored layer without providing a matting layer 2 to achieve a matte finish. However, in this case, the gloss value of the colored layer is not stable, and because the matting agent and pigment in the colored layer are mixed, the gloss value of the colored layer tends to change depending on the thickness of the colored layer and how the colored layer dries.

[0039] Furthermore, if the colored adhesive tape is formed with a laminated structure of "resin film layer 3 / colored layer 4 / adhesive layer 5 / release film 6" without the matte layer 2, a matte finish cannot be obtained. If the colored adhesive tape is formed with a laminated structure of "matte layer 2 / resin film layer 3 / adhesive layer 5 with added colorant / release film 6", it is difficult to achieve both adhesive performance and black density in the adhesive layer 5. Moreover, if the colored adhesive tape is formed with a laminated structure of "matte layer 2 / resin film layer 3 with added colorant / adhesive layer 5 / release film 6", there is a problem in that a sufficient black density cannot be obtained.

[0040] As described above, in this embodiment, the colored adhesive tape 1 can be obtained with a uniform surface shape by laminating each layer in an appropriate order without adding a coloring agent to other layers. [Examples]

[0041] Examples of the colored adhesive tape according to the present invention are described below. However, the present invention is not limited to the following embodiments. The following procedure was used to prepare and evaluate the colored adhesive tapes for Examples 1-12 and Comparative Examples 1-3. The composition of each colored adhesive tape for evaluation is shown in Tables 1-1, 1-2, and 2, and the evaluation results for each colored adhesive tape are shown in Table 3. Each colored adhesive tape was made in A4 size.

[0042] [Table 1-1]

[0043] [Table 1-2]

[0044] [Table 2]

[0045] (Example 1) (1) Production of acrylic copolymer A (solution polymerization) Ethyl acetate was added to the reaction vessel as a polymerization solvent, and after bubbling with nitrogen, the reaction vessel was heated while introducing nitrogen to initiate reflux. Subsequently, a polymerization initiator solution prepared by diluting 0.1 parts by weight of azobisisobutyronitrile 10-fold with ethyl acetate was added to the reaction vessel as a polymerization initiator, and 56.9 parts by weight of butyl acrylate, 40 parts by weight of 2-ethylhexyl acrylate, 3 parts by weight of acrylic acid, and 0.1 parts by weight of 2-hydroxyethyl acrylate were added dropwise over 2 hours. After the dropwise addition was complete, a polymerization initiator solution prepared by diluting 0.1 parts by weight of azobisisobutyronitrile 10-fold with ethyl acetate was added again to the reaction vessel as a polymerization initiator, and the polymerization reaction was carried out for 4 hours to obtain a solution containing acrylic copolymer A.

[0046] The obtained acrylic copolymer A-containing solution was diluted 50-fold with tetrahydrofuran (THF), and the resulting dilution was filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm) to prepare the measurement sample. This measurement sample was supplied to a gel permeation chromatograph (Waters, 2690 Separations Model), and GPC measurement was performed under conditions of sample flow rate of 1 ml / min and column temperature of 40°C. The weight-average molecular weight of acrylic copolymer A, calculated in polystyrene equivalent, was 1.28 million. To the obtained acrylic copolymer A-containing solution, 25 parts by weight of polymerized rosin ester (Arakawa Chemical Industries, Ltd., Pencel D-135) and 4 parts by weight of isocyanate-based crosslinking agent (Mitsui Chemicals, Ltd., Takenate D-101E) were added per 100 parts by weight of acrylic copolymer A to obtain an acrylic adhesive (hereinafter referred to as acrylic adhesive a).

[0047] (2) Manufacturing of colored adhesive tape A PET film was prepared as the resin film layer, and a coating for forming a colored layer was applied to one side of the resin film layer using a bar coater. The wire bar used at this time was #8. After coating, it was dried in an 80°C oven for 2 minutes to form the colored layer. The thickness of the colored layer after drying was 2.5 μm. Next, a coating for forming a matte layer was applied to the other side of the resin film layer, which had a colored layer formed on one side, using a bar coater. The wire bar used at this time was #5. After coating, it was dried in an 80°C oven for 2 minutes, and then aged in a 40°C oven for 1 day to form a matte layer. The thickness of the matte layer after aging was 1.5 μm.

[0048] Next, a 38 μm thick PET film with a silicone release surface was prepared as a release film, and an acrylic adhesive for forming an adhesive layer was applied to the silicone release surface of the release film using an applicator. After application, the film was dried in an oven at 110°C for 2 minutes to form an adhesive layer. The thickness of the adhesive layer was 2 μm. Next, the colored side of the resin film layer and the adhesive side of the release film were placed facing each other and bonded together with a roller, then aged in a 40°C oven for two days. This resulted in a colored adhesive tape consisting of a laminate of "matte layer / resin film layer / colored layer / adhesive layer / release film".

[0049] At this time, the following materials were used as the paint for forming the matte layer, the resin film layer, the paint for forming the colored layer, the acrylic adhesive for forming the adhesive layer, and the release film. Matte finish Resin: Polyester resin (Byron 200, manufactured by Toyobo Co., Ltd.) Isocyanates: Aliphatic isocyanates HDI Matting agent: Silica (Silophobic 100, manufactured by Fuji Silicia Chemical Co., Ltd.) Pigment: None Solvent: "Toluene:MEK = 1:1" Composition: "Resin:Isocyanate:Matte agent:Solvent:Pigment = 20:3:5:72:0"

[0050] resin film layer 2μm polyester film (Lumirror 2-F51, manufactured by Toray Industries, Inc.) colored layer Resin: Polyester resin (Byron 200, manufactured by Toyobo Co., Ltd.) Isocyanates: Aliphatic isocyanates HDI Pigment: Carbon Black Solvent: "Toluene:MEK = 1:1" Composition: "Resin:Isocyanate:Pigment:Solvent = 20:3:15:62" adhesive layer Acrylic adhesive a

[0051] Furthermore, the gel fraction of the adhesive layer obtained from the acrylic adhesive a was measured using the method described in equation (1) above and was found to be 35%. The glass transition temperature (Tg) was measured using the method described below and was found to be 3°C. The glass transition temperature (Tg) of the adhesive layer obtained from acrylic adhesive a was determined by measuring the storage modulus G' and loss modulus G'' at each temperature using a polymer dynamic viscoelasticity analyzer "itkDVA-200" (manufactured by IT Measurement Control Co., Ltd.) under the following conditions. The tanδ at each temperature was calculated, and the temperature at which tanδ took its peak value was defined as Tg. Measurement mode: Shear Heating rate: 5°C / min Measurement temperature range: -30 to 150°C Setting distortion: 0.1% Frequency: 1Hz

[0052] The sample was prepared by heating and drying an acrylic adhesive a under the same conditions as when the adhesive layer was formed, and then shaping it so that the final sample had a thickness of 1 mm, a width of 6 mm, and a length of 10 mm. Release film Silicone-release treated PET film (SP3000, manufactured by Toyo Cloth Co., Ltd.)

[0053] (Example 2) In Example 1, a colored adhesive tape was obtained using the same procedure as in Example 1, except that the paint used to form the colored layer was different. The materials of the paint used to form the colored layer in Example 2 are as follows. colored layer Resin: Polyester resin (Byron 200, manufactured by Toyobo Co., Ltd.) Isocyanates: Aliphatic isocyanates HDI Pigments: 15 parts carbon black, 1 part phthalocyanine blue Solvent: "Toluene:MEK = 1:1" Composition: "Resin:Isocyanate:Pigment:Solvent = 20:3:16:62"

[0054] (Example 3) In Example 1, a colored adhesive tape was obtained using the same procedure as in Example 1, except that the paint used to form the colored layer was different. The materials of the paint used to form the colored layer in Example 3 are as follows. colored layer Resin: Acrylic resin Isocyanates: Aliphatic isocyanates HDI Pigment: Carbon Black Solvent: "Toluene:MEK = 1:1" Composition: "Resin:Isocyanate:Pigment:Solvent = 20:3:16:62"

[0055] (Example 4) In Example 1, a colored adhesive tape was obtained using the same procedure as in Example 1, except that the material of the paint used to form the matte layer was different. The material of the paint used to form the matte layer in Example 4 is as follows. Matte finish Resin: Polyester resin (Byron 200, manufactured by Toyobo Co., Ltd.) Isocyanates: Aliphatic isocyanates HDI Matting agent: Silica (Silophobic 100, manufactured by Fuji Silicia Chemical Co., Ltd.) Pigment: Carbon Black Solvent: "Toluene:MEK = 1:1" Composition: "Resin:Isocyanate:Matte agent:Solvent:Pigment = 20:3:5:72:1"

[0056] (Example 5) In Example 1, a colored adhesive tape was obtained using the same procedure as in Example 1, except that the amount of paint used to form the matte layer was different. In Example 5, the matte layer was formed using the following procedure. A resin film layer with a colored layer formed on one side was coated with a matte coating paint using a bar coater on the other side. The wire bar used was #8. After coating, the film was dried in an 80°C oven for 2 minutes, and then aged in a 40°C oven for 1 day to form the matte layer. The thickness of the matte layer after aging was 3.0 μm.

[0057] (Example 6) In Example 1, a colored adhesive tape was obtained using the same procedure as in Example 1, except that the amount of paint used to form the matte layer was different. In Example 6, the matte layer was formed using the following procedure. A resin film layer with a colored layer formed on one side was coated with a matte coating paint on the other side using a bar coater. The wire bar used was #3. After coating, the film was dried in an 80°C oven for 2 minutes, and then aged in a 40°C oven for 1 day to form the matte layer. The thickness of the matte layer after aging was 0.5 μm.

[0058] (Examples 7-12) In Example 1, a colored adhesive tape was obtained using the same procedure as in Example 1, except that the adhesive used for forming the adhesive layer was different. In Examples 7 to 12, the adhesives shown in Table 1-2 were used for forming the adhesive layer. Specifically, in Examples 7 to 12, acrylic adhesives b to g were used as the adhesives for forming the adhesive layer, respectively. These acrylic adhesives b to g were prepared using the following procedure.

[0059] (1-1) Production of acrylic copolymer B (solution polymerization) Ethyl acetate was added to the reaction vessel as the polymerization solvent, and after bubbling with nitrogen, the reaction vessel was heated while introducing nitrogen to initiate reflux. Subsequently, a polymerization initiator solution prepared by diluting 0.1 parts by weight of azobisisobutyronitrile 10-fold with ethyl acetate was added to the reaction vessel, and 96.6 parts by weight of n-heptyl acrylate, 2.9 parts by weight of acrylic acid, and 0.5 parts by weight of 2-hydroxyethyl acrylate were added dropwise over 2 hours. After the dropwise addition was complete, the polymerization initiator solution prepared by diluting 0.1 parts by weight of azobisisobutyronitrile 10-fold with ethyl acetate was added again to the reaction vessel, and the polymerization reaction was carried out for 4 hours to obtain a solution containing acrylic copolymer B.

[0060] The obtained acrylic copolymer B-containing solution was diluted 50-fold with tetrahydrofuran (THF), and the resulting dilution was filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm) to prepare the measurement sample. This measurement sample was supplied to a gel permeation chromatograph (Waters, 2690 Separations Model), and GPC measurement was performed under conditions of sample flow rate of 1 ml / min and column temperature of 40°C. The weight-average molecular weight of acrylic copolymer B, calculated using polystyrene equivalent molecular weight, was 1 million.

[0061] To the obtained acrylic copolymer B-containing solution, 14 parts by weight of polymerized rosin ester (hydroxyl value: 46, softening point: 152°C), 10 parts by weight of hydrogenated rosin ester (Arakawa Chemical Industries, Ltd., KE359), 10 parts by weight of terpene phenol (Yasuhara Chemical Co., Ltd., G150), and 0.5 parts by weight of isocyanate-based crosslinking agent (Mitsui Chemicals, Ltd., Takenate D-101E) were added per 100 parts by weight of acrylic copolymer B to obtain an acrylic adhesive (hereinafter referred to as acrylic adhesive b). Furthermore, the gel fraction of the adhesive layer obtained from the acrylic adhesive b was measured using the method described in equation (1) above and was found to be 35%. The glass transition temperature (Tg) of the adhesive layer was measured using the same method as in Example 1 and was found to be -8°C.

[0062] (1-2) Production of acrylic copolymer C (solution polymerization) Ethyl acetate was added to the reaction vessel as the polymerization solvent, and after bubbling with nitrogen, the reaction vessel was heated while introducing nitrogen to initiate reflux. Subsequently, a polymerization initiator solution prepared by diluting 0.1 parts by weight of azobisisobutyronitrile 10-fold with ethyl acetate was added to the reaction vessel, and 95.1 parts by weight of n-heptyl acrylate, 4.8 parts by weight of acrylic acid, and 0.1 parts by weight of 2-hydroxyethyl acrylate were added dropwise over 2 hours. After the dropwise addition was complete, the polymerization initiator solution prepared by diluting 0.1 parts by weight of azobisisobutyronitrile 10-fold with ethyl acetate was added again to the reaction vessel, and the polymerization reaction was carried out for 4 hours to obtain a solution containing acrylic copolymer C.

[0063] The obtained acrylic copolymer C-containing solution was diluted 50-fold with tetrahydrofuran (THF), and the resulting dilution was filtered through a filter (material: polytetrafluoroethylene, pore diameter: 0.2 μm) to prepare the measurement sample. This measurement sample was supplied to a gel permeation chromatograph (Waters, 2690 Separations Model), and GPC measurement was performed under conditions of sample flow rate of 1 ml / min and column temperature of 40°C. The weight-average molecular weight of acrylic copolymer C, calculated using polystyrene equivalent molecular weight, was 1.2 million.

[0064] To the obtained acrylic copolymer C-containing solution, 14 parts by weight of polymerized rosin ester (hydroxyl value: 46, softening point: 152°C), 10 parts by weight of hydrogenated rosin ester (Arakawa Chemical Industries, Ltd., KE359), 10 parts by weight of terpene phenol (Yasuhara Chemical Co., Ltd., G150), and 2.5 parts by weight of isocyanate-based crosslinking agent (Mitsui Chemicals, Ltd., Takenate D-101E) were added as tackifying resins per 100 parts by weight of acrylic copolymer C to obtain an acrylic adhesive (hereinafter referred to as acrylic adhesive c). Furthermore, the gel fraction of the adhesive layer obtained from the acrylic adhesive c was measured using the method described in equation (1) above and was found to be 35%. The glass transition temperature (Tg) of the adhesive layer was measured using the same method as in Example 1 and was found to be -1°C.

[0065] To the obtained acrylic copolymer C-containing solution, 24 parts by weight of polymerized rosin ester (hydroxyl value: 46, softening point: 152°C) as a tackifying resin, 10 parts by weight of terpene phenol (manufactured by Yasuhara Chemical Co., Ltd., G150), and 2.5 parts by weight of isocyanate-based crosslinking agent (manufactured by Mitsui Chemicals, Inc., Takenate D-101E) were added per 100 parts by weight of acrylic copolymer C to obtain an acrylic adhesive (hereinafter referred to as acrylic adhesive d). Furthermore, the gel fraction of the adhesive layer obtained from the acrylic adhesive d was measured using the method described in equation (1) above and was found to be 30%. The glass transition temperature (Tg) of the adhesive layer was measured using the same method as in Example 1 and was found to be 0°C.

[0066] To the obtained acrylic copolymer C-containing solution, 14 parts by weight of polymerized rosin ester (hydroxyl value: 46, softening point: 152°C), 10 parts by weight of hydrogenated rosin ester (Arakawa Chemical Industries, Ltd., KE359), 10 parts by weight of terpene phenol (Yasuhara Chemical Co., Ltd., G150), and 0.1 parts by weight of epoxy crosslinking agent (Soken Chemical Co., Ltd., A-EX, 5% solids) were added as tackifying resins, per 100 parts by weight of acrylic copolymer C, to obtain an acrylic adhesive (hereinafter referred to as acrylic adhesive e). Furthermore, the gel fraction of the adhesive layer obtained from the acrylic adhesive e was measured using the method described in equation (1) above and was found to be 55%. The glass transition temperature (Tg) of the adhesive layer was measured using the same method as in Example 1 and was found to be 1°C.

[0067] To the obtained acrylic copolymer C-containing solution, 14 parts by weight of polymerized rosin ester (hydroxyl value: 46, softening point: 152°C), 10 parts by weight of hydrogenated rosin ester (Arakawa Chemical Industries, Ltd., KE359), 10 parts by weight of terpene phenol (Yasuhara Chemical Co., Ltd., G150), 1.2 parts by weight of isocyanate-based crosslinking agent (Mitsui Chemicals, Ltd., Takenate D-101E), and 0.05 parts by weight of epoxy-based crosslinking agent (Soken Chemical Co., Ltd., A-EX, 5% solids) were added as tackifying resins, per 100 parts by weight of acrylic copolymer C, to obtain an acrylic adhesive (hereinafter referred to as acrylic adhesive f). Furthermore, the gel fraction of the adhesive layer obtained from the acrylic adhesive f was measured using the method described in equation (1) above and was found to be 65%. The glass transition temperature (Tg) of the adhesive layer was measured using the same method as in Example 1 and was found to be 2°C.

[0068] To the obtained acrylic copolymer C-containing solution, 14 parts by weight of polymerized rosin ester (hydroxyl value: 46, softening point: 152°C), 10 parts by weight of hydrogenated rosin ester (Arakawa Chemical Industries, Ltd., KE359), 10 parts by weight of terpene phenol (Yasuhara Chemical Co., Ltd., G150), 2.5 parts by weight of isocyanate-based crosslinking agent (Mitsui Chemicals, Ltd., Takenate D-101E), and pigment (Dainichi Seika Kogyo Co., Ltd., Multi-Rack A903, solids content 55%) were added to obtain an acrylic adhesive (hereinafter referred to as acrylic adhesive g) per 100 parts by weight of acrylic copolymer C. Furthermore, the gel fraction of the adhesive layer obtained from the acrylic adhesive g was measured using the method described in equation (1) above and was found to be 35%. The glass transition temperature (Tg) of the adhesive layer was measured using the same method as in Example 1 and was found to be -1°C.

[0069] (Comparative Example 1) In Example 1, a colored adhesive tape was prepared using the same procedure as in Example 1, except that the amount of paint used to form the matte layer was different. In Comparative Example 1, the matte layer was formed using the following procedure. A resin film layer with a colored layer formed on one side was coated with the following matte coating paint using a bar coater. The wire bar used was #3. After coating, the film was dried in an 80°C oven for 2 minutes, and then aged in a 40°C oven for 1 day to form the matte layer. The thickness of the matte layer after aging was 0.3 μm. Matte finish Resin: Polyester resin (Byron 200, manufactured by Toyobo Co., Ltd.) Isocyanates: Aliphatic isocyanates HDI Matting agent: Silica (Silophobic 100, manufactured by Fuji Silicia Chemical Co., Ltd.) Pigment: None Solvent: "Toluene:MEK = 1:1" Composition: "Resin:Isocyanate:Matte agent:Solvent:Pigment = 20:3:5:90:0"

[0070] (Comparative Example 2) In Example 1, a colored adhesive tape was prepared using the same procedure as in Example 1, except that the lamination order of the colored layer and the resin film layer was different. In Comparative Example 2, a colored adhesive tape was prepared using the following procedure. A PET film was prepared as the resin film layer, and a coating for forming a colored layer was applied to one side of the resin film layer using a bar coater. The wire bar used at this time was #8. After coating, it was dried in an 80°C oven for 2 minutes to form the colored layer. The thickness of the colored layer after drying was 2.5 μm.

[0071] Next, a paint for forming a matte layer was applied to the colored layer using a bar coater. The wire bar used at this time was #5. After coating, it was dried in an 80°C oven for 2 minutes, and then aged in a 40°C oven for 1 day to form a matte layer. The thickness of the matte layer after aging was 1.5 μm. Next, a 38 μm thick nPET film with a silicone release surface was prepared as a release film, and an acrylic adhesive for forming an adhesive layer was applied to the silicone release surface of the release film using an applicator. After application, the film was dried in an oven at 110°C for 2 minutes to form an adhesive layer. The thickness of the adhesive layer was 2 μm. Next, the colored side of the resin film layer and the adhesive side of the release film were placed facing each other and bonded together with a roller, then aged in a 40°C oven for two days. This resulted in a colored adhesive tape consisting of a laminate of "matte layer / colored layer / resin film layer / adhesive layer / release film".

[0072] (Comparative Example 3) In Example 1, a colored adhesive tape was prepared using the same procedure as in Example 1, except that it did not have a matte layer. In Comparative Example 3, a colored adhesive tape was prepared using the following procedure. A PET film was prepared as the resin film layer, and a coating for forming a colored layer was applied to one side of the resin film layer using a bar coater. The wire bar used at this time was #8. After coating, it was dried in an 80°C oven for 2 minutes to form the colored layer. The thickness of the colored layer after drying was 2.5 μm.

[0073] Next, a 38 μm thick PET film with a silicone release surface was prepared as a release film, and a coating for forming an adhesive layer was applied to the silicone release surface of the release film using an applicator. After application, it was dried in an oven at 110°C for 2 minutes to form an adhesive layer. The thickness of the adhesive layer was 2 μm. Next, the colored side of the resin film layer and the adhesive side of the release film were placed facing each other and bonded together with a roller, then aged in a 40°C oven for two days. This resulted in a colored adhesive tape consisting of a laminate of "resin film layer / colored layer / adhesive layer / release film".

[0074] (Evaluation method) For the colored adhesive tapes used for evaluation in Examples 1-12 and Comparative Examples 1-3, the total film thickness, transmittance, gloss value, surface quality, and hue were evaluated. (Total film thickness) The total thickness of the colored adhesive tape was measured as the total film thickness. For total film thickness, a value of ○ was used if the thickness was between 5 μm and 10 μm, and × was used if it was outside this range.

[0075] (transmittance) The light transmittance (total light transmittance) of the laminate excluding the release film was measured for each colored adhesive tape. Light transmittance was measured in accordance with JIS K7105 using the "HR-100" manufactured by Murakami Color Technology Laboratory. A value of ○ indicates that the light transmittance is 5% or less, while a value of × indicates that it is greater than 5%. (Gross value) The gloss value of the matte layer surface of colored adhesive tape was measured. The gloss value was measured using a commercially available gloss meter (for example, the "High Gloss Checker IG-410" manufactured by Horiba, Ltd.) at a measurement angle of 60°. A gross value of 3.0 or less at a measurement angle of 60° was marked with ○, and a value greater than 3.0 was marked with ×.

[0076] (face) The surface of the colored adhesive tape, specifically the side opposite the release film, was visually inspected to evaluate its surface quality. The uniformity and lack of unevenness of the colored adhesive tape surface were assessed. A uniform surface of the colored adhesive tape was marked with ○, while an uneven or patchy surface was marked with ×. (hue) The hue of the surface of the colored adhesive tape was observed visually, and the difference in hue compared to the colored adhesive tape in Example 1 was observed.

[0077] [Table 3]

[0078] As shown in Table 3, the colored adhesive tapes of Examples 1 to 12, which have a structure in which a matte layer, a resin film layer, a colored layer, an adhesive layer, and a release film are laminated in order from the release film side, and which satisfy the requirement that the thickness of the matte layer is 0.5 μm or more and 3 μm or less, had a light transmittance of 2.5% and a 60° gloss value of 1.5 for Examples 1 to 4 and Examples 7 to 12, 0.9 for Example 5, and 2.9 for Example 6. It was confirmed that they had good color, texture, and matte feel, and a uniform and even surface. Furthermore, as shown in Examples 7 to 12, it was confirmed that even when the components constituting the adhesive layer were different, they still had good color, texture, and matte feel, and a uniform and even surface.

[0079] Furthermore, in Example 2, the colored adhesive tape used phthalocyanine blue in addition to carbon black as a pigment in the colored layer, resulting in increased blueness in the obtained colored adhesive tape. Moreover, it was confirmed that even in Example 3, where an acrylic resin was used instead of a polyester resin for the colored layer, the same effect as in Example 1, which used a polyester resin, could be obtained. When an acrylic resin is used, further improvement in blocking properties can be expected. In addition, in Example 4, where carbon black was added as a pigment to the matte layer, it was confirmed that the blackness was increased compared to the colored adhesive sheet of Example 1, where no pigment was added to the matte layer.

[0080] Furthermore, in Comparative Example 1, where the thickness of the matte layer was 0.3 μm, the high 60° gloss value made it difficult to achieve a matte finish, and the inspection light source used for defect inspection reflected off the surface of the matte layer, making it difficult to detect defects. On the other hand, in Example 5, where the thickness of the matte layer was 3.0 μm, a sufficient matte finish was obtained. Furthermore, in Comparative Example 2, a colored adhesive tape in which a matte layer was directly laminated on top of a colored layer, the surface of the colored layer in contact with the matte layer became rough due to the influence of the solvent in the matte layer. As a result, the surface of the colored adhesive tape on the side opposite the release film, i.e., the surface on the matte layer side, had many irregularities, and its aesthetic appeal was reduced.

[0081] Furthermore, the colored adhesive tape of Comparative Example 3, which does not have a matte layer, has a gloss value of 113, failing to achieve a matte finish. In addition, the inspection light source used for defect inspection is reflected off the surface of the resin film layer, making it even more difficult to detect defects than in Comparative Example 1. Furthermore, when the water contact angle for Examples 1 to 4 was measured in accordance with JIS R 3257:1999, it was found to be 105°, confirming that the antifouling properties were sufficiently high.

[0082] Furthermore, the present invention can take the following configuration, for example. (1) A colored adhesive tape in which a release film, an adhesive layer, a colored layer, a resin film layer, and a matte layer are laminated in this order, The aforementioned matte layer mainly consists of a polyester resin, isocyanate, and a matting agent, the matting agent containing silica, and the layer has a thickness of 0.5 μm to 3 μm. The colored adhesive tape is characterized in that the colored layer is a layer mainly composed of a resin, isocyanate, and a pigment containing carbon black. (2) The colored adhesive tape according to (1) above, characterized in that the light transmittance of the laminate of the adhesive layer, the colored layer, the resin film layer, and the matte layer is 5% or less. (3) The colored adhesive tape according to (1) or (2) above, characterized in that the 60° gloss value of the surface on the matte layer side is 3 or less. (4) The colored adhesive tape according to any one of (1) to (3) above, characterized in that the matte layer is colored. (5) A colored adhesive tape according to any one of the above items (1) to (4), characterized in that it is for surface protection of a heat dissipation sheet. (6) A colored adhesive tape according to any one of the above items (1) to (4), characterized in that it is for surface protection of a magnetic sheet. [Explanation of Symbols]

[0083] 1. Colored adhesive tape 2. Matte layer 3. Resin film layer 4 Colored layer 5 Adhesive layer 6. Release film 10. Heat dissipation sheet or magnetic sheet

Claims

1. A colored adhesive tape in which a release film, an adhesive layer, a colored layer, a resin film layer, and a matte layer are laminated in this order, The aforementioned matte layer mainly consists of a polyester resin, isocyanate, and a matting agent, the matting agent containing silica, and the layer has a thickness of 0.5 μm to 3 μm. The colored adhesive tape is characterized in that the colored layer is a layer mainly composed of a resin, isocyanate, and a pigment containing carbon black.

2. The colored adhesive tape according to claim 1, characterized in that the light transmittance of the laminate of the adhesive layer, the colored layer, the resin film layer, and the matte layer is 5% or less.

3. The colored adhesive tape according to claim 1 or 2, characterized in that the 60° gloss value of the surface on the matte layer side is 3 or less.

4. The colored adhesive tape according to claim 1 or 2, characterized in that the matte layer is colored.

5. A colored adhesive tape according to claim 1 or 2, characterized in that it is for surface protection of a heat dissipation sheet.

6. A colored adhesive tape according to claim 1 or 2, characterized in that it is for protecting the surface of a magnetic sheet.

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