JP7263836B2 - black polyimide adhesive tape - Google Patents

Description

TECHNICAL FIELD The present invention relates to a black polyimide pressure-sensitive adhesive tape that can be suitably used, for example, for covering parts (graphite sheets and magnetic sheets) in portable electronic devices.

Colored adhesive tapes are used in various industrial fields for purposes such as decoration, display, concealment, and insulation. In particular, in electronic devices such as personal computers, digital video cameras, electronic notebooks, mobile phones, PHS, smart phones, game machines, and electronic books, black-colored adhesive tapes are preferred and used from the standpoint of concealment and insulation. In recent years, the amount of heat generated has increased due to the high performance of parts to which they are attached, and the demand for highly heat-resistant polyimide film tapes is increasing. However, since polyimide is colored yellow, unlike transparent PET, it has the problem that it is difficult to manage the color when it is attached to an adherend. It was not known (Patent Document 1).

JP 2012-177069

Under such circumstances, the present invention has been made by optimizing the thickness of the base material of polyimide, the thickness of the black colored layer, the thickness of the matte layer, and the CIE color value, thereby producing parts (graphite sheets) in portable electronic devices. We realized a thin black polyimide adhesive tape with high heat resistance and high design, which is used for the cover of magnetic sheets).

As a result of intensive studies by the present inventors in order to achieve the above objects, it was found that a printing substrate having a specific substrate thickness, printing thickness, and transmittance, and a specific gel fraction and molecular weight pressure-sensitive adhesive can be used. The inventors have found that the object can be achieved, and completed the present invention.

That is, the present invention comprises a polyimide film layer with a thickness of 1.0 to 15.0 μm, a black colored layer with a thickness of 1.5 to 3.0 μm, and a glossy layer with a thickness of 1.0 to 5.0 μm. 5.0 to 30.0 μm in thickness, characterized by having a colored substrate having an erasing layer and an adhesive layer, and having CIE color values (L*, a*, b*) in the following ranges black polyimide adhesive tape.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a black polyimide pressure-sensitive adhesive tape that is used as a cover for parts (graphite sheets and magnetic sheets) in portable electronic devices and has excellent design and excellent heat resistance.

(polyimide film layer)
The polyimide film of the colored substrate of the present invention has a thickness of 1.0 to 15.0 μm, more preferably 2.0 to 12.5 μm, still more preferably 3.0 to 7.5 μm. be. By using a film of this thickness, it is easy to achieve suitable printability and heat resistance even with an ultra-thin structure, and it is suitable for covering parts (graphite sheets and magnetic sheets) in portable electronic devices. A black polyimide adhesive tape is obtained.

As a polyimide film constituting the polyimide film layer, a polyimide film used as a base material for adhesive tapes can be used. Among them, a polyimide film having a tensile strength of 100 MPa to 1000 MPa is preferable because it is difficult to cut even in an ultra-thin structure, more preferably 150 MPa to 800 MPa, and still more preferably 200 MPa to 500 MPa.

Various black coloring pigments may be mixed in the polyimide film constituting the polyimide film layer, but a transparent resin film is preferable in order to realize suitable inspection properties. In addition, by using a transparent film that does not use a coloring pigment, it becomes easy to achieve high strength even with an ultra-thin structure.
The polyimide film is preferably a biaxially stretched film from the viewpoint of dimensional stability and strength.

In addition, the surface of the polyimide film layer is subjected to a conventional surface treatment such as chromic acid treatment, ozone exposure, flame exposure, high pressure treatment, etc., in order to improve adhesion with the colored layer or adhesive layer formed on the resin film layer. It may be oxidized by a chemical or physical method such as electric shock exposure or ionizing radiation treatment, or may be coated with a primer.

(Black colored layer)
The black colored layer of the colored substrate of the present invention is a layer that adjusts the CIE color values (L*, a*, b*) and light transmittance of the black polyimide adhesive tape within a predetermined range. It can be prepared by applying an ink to be described later.

The black colored layer has a thickness of 1.5 to 3.0 μm, preferably 1.5 to 2.5 μm. By setting the black colored layer to this range, it is possible to achieve a high degree of compatibility between suitable concealing properties, inspection properties, and design properties in spite of the ultra-thin structure.

In addition, the light transmittance of the black colored layer may be in a range where the light transmittance when used as a colored substrate is 0.1 to 10%, but when combined with the transparent resin film layer, the black colored layer The light transmittance of the layer is preferably 0.1 to 10%, more preferably 0.3 to 8%, even more preferably 0.4 to 5%. In addition, the light transmittance in this application means the light transmittance Tt measured according to JIS K7105.

Although the black colored layer is not particularly limited, it is preferably a layer made of black ink. The black ink layer is preferably a layer made of urethane-based ink containing a urethane-based resin having a glass transition temperature (Tg) of -30 to 10°C as a main binder component. Compared to polyester-based or acrylic-based inks, urethane-based inks are less likely to curl even with thin films, and can disperse pigments at high concentrations.

A black ink layer is provided on the resin film by a known printing method such as direct gravure printing, reverse gravure printing, or small-diameter gravure printing. Among them, direct gravure printing is preferable because even thin resin films are difficult to tear and have excellent printability.

The composition of black ink includes poly(meth)acrylic resin, polyester resin, polyvinyl acetate resin, polyvinyl chloride resin, polyvinyl butyral resin, cellulose resin, polystyrene/polybutadiene resin, polyurethane resin, alkyd resin, and acrylic resin. , unsaturated polyester resin, epoxy ester resin, epoxy resin, epoxy acrylate resin, urethane acrylate resin, polyester acrylate resin, polyether acrylate resin, phenol resin, melamine resin, urea resin, diallyl phthalate resin and thermoplastic or thermosetting resins such as , and these can be used singly or in combination of two or more. Among them, the polyester urethane type is preferable. Further, the polyester urethane resin preferably has a glass transition temperature of -30 to 10°C. By using this polyester urethane-based resin, even when an ultra-thin adhesive tape is configured and a thin film is coated, there is little curling, and even thin resin films that are difficult to be easily adhered to, such as corona treatment, can be used firmly. Adhesion can be achieved, and good adhesiveness and reworkability can be achieved. More preferably -25°C to 0°C, particularly preferably -20°C to -5°C. The glass transition degree of the polyester urethane resin is the peak temperature of tan δ in the dynamic viscoelasticity spectrum at a frequency of 1 Hz measured below.

A polyester urethane resin is obtained by a polycondensation reaction of a diisocyanate compound, a polyester polyol compound, a low-molecular-weight chain extender, etc., and is a flexible and elastic resin having many urethane bonds in the molecule. The polyester polyol compound contains a dicarboxylic acid as a monomer component, and the aromatic dicarboxylic acid in the dicarboxylic acid is preferably 30 to 90% by mass because it is easy to control the tan δ peak temperature of the polyester urethane resin within the above range. The molecular weight of the polyester polyol is not particularly limited, but the number average molecular weight is preferably 800 to 6,000. When the number average molecular weight of the polyester polyol is 800 or more, the resulting polyester urethane resin tends to have favorable printability and coatability, and when it is 6,000 or less, drying property and blocking resistance tend to be improved. . The polyester urethane resin preferably has a mass average molecular weight of 1,000 to 500,000, more preferably 20,000 to 150,000.

The black ink preferably has CIE color values (L*, a*, b*) within the following ranges when printed at a dry thickness of 1.0 μm.
That is, 16≦L*≦34, −3≦a*≦3, −5≦b*≦1.
More preferably, 18≦L*≦32, −2≦a*≦2, −4≦b*≦0.5, and still more preferably 20≦L*≦30, −1≦a*≦1, − 3≤b*≤0.

The said average mass molecular weight is standard polystyrene conversion by a gel permeation chromatography (GPC). As measurement conditions, a TSKgel GMHXL column (manufactured by Tosoh Corporation) is used, the column temperature is 40° C., the eluent is tetrahydrofuran, the flow rate is 1.0 mL/min, and the standard polystyrene is TSK standard polystyrene.

The black ink used for the black colored layer contains a binder resin and a coloring material. As the coloring material, conventional halogen-free pigments and dyes can be used. In the case of black, carbon black, acetylene black, lamp black, bone black, graphite, iron black, mineral black, aniline black, cyanine. Black or the like can be used. Of these, carbon black is preferred because of its weather resistance, heat resistance, and dispersibility in ink resins.

The amount of the coloring material to be added may be appropriately adjusted depending on the application, and is preferably 10 to 70% by mass based on the solid content of the ink containing the coloring material. More preferably 20 to 60 mass %, still more preferably 35 to 50 mass %. If the content is 10% by mass or more, the masking property is suitably exhibited, and if it is 70% by mass or less, the dispersion is good.

(Matte layer)
The matte layer of the colored substrate of the present invention contains particles. The matte layer is preferably laminated on top of the black colored layer. By providing the matte layer on the outside of the black colored layer separately from the black colored layer, high designability, fingerprint resistance, and scratch resistance can be obtained. The matte layer may be directly laminated on the black colored layer, or may be laminated with the black colored layer via another layer.

Particles contained in the matte layer include, for example, organic particles and inorganic particles. Organic particles are preferred from the standpoint of inconspicuous scratches. In addition, from the viewpoint of hardness and heat resistance, inorganic particles are preferred.

The organic particles are not particularly limited, and examples thereof include acrylic resin particles such as polymethyl methacrylate particles, polystyrene particles, polycarbonate particles, urethane resin beads, epoxy resin beads, polyester resin beads, and polyester urethane resin beads. These may be used alone, or two or more of them may be used in combination. Among them, urethane resin beads are preferable because of their excellent flexibility.

The inorganic particles are not particularly limited, and examples thereof include particles made of silicon dioxide, titanium dioxide, barium sulfate, silica, calcium carbonate, and the like. These may be used alone, or two or more of them may be used in combination. Among these, silica particles are preferable because of ease of particle size adjustment and availability.

The silica particles preferably have an average particle size of 2.0 μm to 6.0 μm as measured by the coal counter method. It is more preferably 2.3 μm to 5.0 μm, most preferably 3.0 μm to 4.5 μm. When the average particle size of the silica particles is within the above range, both anti-fingerprint property and adhesiveness can be highly achieved.

The content of silica particles is preferably 10 to 80 parts by mass with respect to 100 parts by mass of the binder resin. More preferably 20 to 75 parts by mass, most preferably 30 to 60 parts by mass. Within the above range, it is possible to achieve a high level of both fingerprint resistance, adhesion and scratch resistance.

Various types of silica such as precipitation silica, gel silica, dry silica, and colloidal silica can be used as silica particles. Among them, precipitated silica and monodisperse colloidal silica are preferable.

Anti-fingerprints are obtained by various treatments such as hydrophobic treatment (silane coupling treatment and surface treatment by chemically bonding silicone oil, etc.), organic treatment (treatment of silica surface with wax), inorganic treatment, etc. on the silica surface. Since it is particularly excellent, it is preferable, and one subjected to silane coupling treatment is particularly preferable.

The composition of the binder resin includes poly(meth)acrylic acid resin, polyester resin, polyvinyl acetate resin, polyvinyl chloride resin, polyvinyl butyral resin, cellulose resin, polystyrene/polybutadiene resin, polyurethane resin, alkyd resin, and acrylic resin. , unsaturated polyester resin, epoxy ester resin, epoxy resin, epoxy acrylate resin, urethane acrylate resin, polyester acrylate resin, polyether acrylate resin, phenol resin, melamine resin, urea resin, diallyl phthalate resin and thermoplastic or thermosetting resins such as , and these can be used singly or in combination of two or more. By making the composition of the binder resin for the matte layer and the binder resin for the black colored layer the same, suitable adhesion between the matte layer and the black colored layer can be realized.

(Colored base material)
The colored substrate used in the present invention includes a polyimide film layer having a thickness of 1.0 to 15.0 μm, a black colored layer having a thickness of 1.5 to 3.0 μm, and a thickness of 1.0 to It is a pigmented substrate with a matte layer of 5.0 μm. The light transmittance of the colored substrate is preferably 0.1 to 10%, more preferably 0.1 to 8%, still more preferably 0.1 to 5.0%. By using a colored base material within this range, the resulting colored pressure-sensitive adhesive tape can achieve suitable design properties, concealment properties, and inspection properties while being extremely thin, and is suitable for sticking with less wrinkles during sticking. Attachability can be achieved.

The thickness of the colored substrate is preferably 3.5 to 15.5 μm, more preferably 4 to 14 μm, particularly preferably 5 to 13 μm. By setting the thickness of the colored base material within this range, wrinkle suppression and cut resistance during application are particularly suitable.

The light transmittance of the colored substrate is 0.1-10%, preferably 0.2-8%, more preferably 0.3-5%. With such a light transmittance, suitable concealability and inspection property can be realized even with an ultra-thin type.

The structure of the colored base material may be a structure having the above polyimide film layer, a black colored layer and a matte layer, and if necessary, the polyimide film layer may be subjected to an easy adhesion treatment, or other layers such as a primer layer may be provided. In addition, the colored substrate may be one having the above light transmittance, but a combination of a transparent resin film layer and a colored layer having a light transmittance of 0.1 to 10% is particularly suitable for hiding properties. It is preferable because it is easy to achieve both inspection performance.

The color tone of the colored substrate is defined by the L*a*b* color system. L* (lightness) is preferably 18≦L*≦36. More preferably 20≤L*≤30, most preferably 22≤L*≤26. a* (chromaticity) is preferably −3≦a*≦3. More preferably -2≤a*≤2, most preferably -1≤a*≤1. b* (chromaticity) is preferably −3≦b*≦3. More preferably -2≤b*≤2, most preferably -1≤b*≤0. Satisfying the above range is preferable because it is particularly easy to achieve both designability and concealability.

JIS Z 8741 defines the glossiness of a colored substrate. The glossiness (gloss: Gu) is preferably 0≦Gu≦10. More preferably 0≦Gu≦6, and most preferably 0≦Gu≦4. Satisfying the above range improves designability.

The thickness ratio of the black colored layer and the matte layer is preferably 1 for the black colored layer and 1 or more for the matte layer. More preferably, the ratio of the black colored layer is 1, and the ratio of the matte layer is 1.5 or more, preferably 2 or more. By setting the ratio within the above range, the design can be easily improved.

(Adhesive layer)
The thickness of the pressure-sensitive adhesive layer of the present invention is preferably 1 to 6 μm, more preferably 2 to 5 μm, even more preferably 2.5 to 4 μm. By being in the above range, it is possible to achieve good adhesive physical properties even when an extremely thin structure is used. In particular, when the thickness is less than 1 μm, the adhesive strength is remarkably lowered, resulting in poor adhesion to adherends.

The adhesive that forms the adhesive layer of the present invention is not particularly limited, and examples thereof include acrylic adhesives, rubber adhesives, silicone adhesives, urethane adhesives, polyester adhesives, and styrene-diene blocks. The adhesive may be appropriately selected from known adhesives such as copolymer-based adhesives, vinyl alkyl ether-based adhesives, polyamide-based adhesives, fluorine-based adhesives, creep property-improved adhesives, and radiation-curable adhesives. can be done. An adhesive can be used individually or in combination of 2 or more types.

As the adhesive, an acrylic adhesive is particularly suitable because of its high adhesion reliability. Acrylic pressure-sensitive adhesives have an acrylic polymer as an adhesive component or main agent, and if necessary, appropriate additives such as cross-linking agents, tackifiers, softeners, plasticizers, fillers, anti-aging agents, and colorants. Contains additives. An acrylic polymer is a polymer whose main monomer component is a (meth)acrylic acid alkyl ester, and if necessary, a monomer (copolymerizable monomer body). Examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, and (meth)acrylate. isobutyl acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, heptyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, undecyl (meth)acrylate , dodecyl (meth)acrylate, tridecyl (meth)acrylate, tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate, heptadecyl (meth)acrylate, octadecyl (meth)acrylate, C1-20 alkyl (meth)acrylate such as nonadecyl (meth)acrylate and eicosyl (meth)acrylate [preferably C4-18 alkyl (linear or branched chain alkyl) (meth)acrylate] etc. The (meth)acrylic acid alkyl ester can be appropriately selected according to the desired adhesiveness and the like. (Meth)acrylic acid alkyl esters may be used alone or in combination of two or more.

Examples of copolymerizable monomers copolymerizable with the (meth)alkyl ester include carboxyl groups such as (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. containing monomers or anhydrides thereof; sulfonic acid group-containing monomers such as sodium vinylsulfonate; aromatic vinyl compounds such as styrene and substituted styrene; cyano group-containing monomers such as acrylonitrile; ethylene, propylene, butadiene, etc. olefins; vinyl esters such as vinyl acetate; vinyl chloride; amide group-containing monomers such as acrylamide, methacrylamide, N-vinylpyrrolidone, N,N-dimethyl (meth)acrylamide; hydroxyalkyl (meth)acrylate , hydroxyl group-containing monomers such as glycerin dimethacrylate; amino group-containing monomers such as aminoethyl (meth) acrylate and (meth) acryloylmorpholine; Epoxy group-containing monomers such as meth)glycidyl acrylate and methylglycidyl (meth)acrylate; isocyanate group-containing monomers such as 2-methacryloyloxyethyl isocyanate, triethylene glycol di(meth)acrylate, diethylene glycol di (Meth)acrylate, ethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, trimethylolpropane tri(meth) Polyfunctional copolymerizable monomers (polyfunctional monomers) such as acrylates, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, divinylbenzene, and the like are included. A copolymerizable monomer can be used individually or in combination of 2 or more types. A modifying monomer having a functional group such as a carboxyl group can be suitably used as the copolymerizable monomer.

The weight average molecular weight (Mw) of the acrylic polymer is preferably 500,000 to 1,200,000. More preferably, it is 600,000 to 1,200,000. Most preferably 700,000 to 1,200,000. Within the above range, even a thin film is likely to exhibit sufficient adhesiveness and heat resistance. The molecular weight is measured in terms of styrene by GPC.

In the present invention, it is also preferable to add a tackifying resin in order to improve the adhesive strength of the adhesive layer. Also, by adding these tackifying resins, it is possible to increase the tensile strength and tensile strength at break. The tensile breaking strength can be adjusted. The tackifier resin added to the adhesive layer of the double-sided pressure-sensitive adhesive tape of the present invention includes, for example, rosin-based resins such as rosin and ester compounds of rosin; terpene-based resins such as diterpene polymers and α-pinene-phenol copolymers. petroleum resins such as aliphatic (C5) and aromatic (C9); other resins include styrene resins, phenol resins, and xylene resins. Among them, in a pressure-sensitive adhesive composition using an acrylic copolymer containing n-butyl (meth)acrylate as a main monomer component, when achieving both thinness and adhesive strength and heat resistance, rosin-based resin and styrene-based resin It is preferable to use a mixture of

Further, in order to increase the initial adhesive strength, it is preferable to mix and use a tackifying resin that is liquid at room temperature. Examples of the tackifying resin that is liquid at room temperature include liquid resins such as the tackifying resins that are solid at room temperature, process oils, polyester plasticizers, and low-molecular-weight liquid rubbers such as polybutene. A terpene phenol resin is particularly preferred. Commercially available products include YP-90L manufactured by Yasuhara Chemical Co., Ltd., and the like. The amount of the liquid crystal tackifying resin to be added is preferably 1 to 20 parts by weight per 100 parts by weight of the acrylic copolymer.

The amount of the tackifying resin to be added is preferably 20 to 60 parts by mass with respect to 100 parts by mass of the acrylic copolymer. More preferably, it is 30 to 50 parts by mass. Adhesion can be improved by adding a tackifying resin.

The gel fraction of the adhesive is not particularly limited, but it is preferable that it is 5 to 50% because it is easy to develop sufficient adhesiveness and heat resistance even if it is a thin film, and it is 10 to 30%. is more preferred, and more preferably 15 to 25%. The gel fraction is obtained by immersing the adhesive layer after curing in toluene, measuring the weight of the remaining insoluble matter after drying for 24 hours, and expressing it as a percentage of the original weight.
Gel fraction = [(mass of adhesive layer after toluene immersion)/(mass of adhesive layer before toluene immersion)] x 100

In order to improve the design and concealability, it is possible to mix a pigment with the pressure-sensitive adhesive. As the pigment, black is preferable, and carbon black, acetylene black, lamp black, bone black, graphite, iron black, mineral black, aniline black, cyanine black, etc. can be used. Among them, carbon black is most preferably used as the pigment in order to form a pressure-sensitive adhesive layer in which the pigment is dispersed relatively uniformly.

Acrylic polymers can be prepared by conventional polymerization methods such as solution polymerization, emulsion polymerization, and ultraviolet irradiation polymerization.

(colored adhesive tape)
The black polyimide pressure-sensitive adhesive tape of the present invention is a colored pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on the reverse side of the colored layer of the colored substrate and having a total thickness of 5 to 20 μm. As described above, the black polyimide pressure-sensitive adhesive tape of the present invention is extremely thin and can be suitably used for protecting parts used in electronic equipment with limited space, especially portable electronic equipment. In addition, since the base material is colored, it has excellent visibility, concealability, and design. In addition, within the thickness range of the colored pressure-sensitive adhesive tape of the present invention, each layer may have a configuration in which a plurality of layers are laminated, or may have a configuration in which another functional layer is included between each layer. .

The light transmittance of the colored adhesive tape is preferably 0.1 to 10%, more preferably 0.3 to 8%, still more preferably 0.4 to 5%.

The color tone of the colored adhesive tape is defined by the L*a*b* color system. L* (lightness) is preferably 18≦L*≦36. More preferably 20≤L*≤30, most preferably 22≤L*≤26. a* (chromaticity) is preferably −3≦a*≦3. More preferably -2≤a*≤2, most preferably -1≤a*≤1. b* (chromaticity) is preferably −3≦b*≦3. More preferably -2≤b*≤2, most preferably -1≤b*≤0. Satisfying the above range is preferable because it is particularly easy to achieve both designability and concealability.

JIS Z 8741 defines the glossiness of the colored pressure-sensitive adhesive tape. The glossiness (gloss: Gu) is preferably 0≦Gu≦10. More preferably 0≦Gu≦6, and most preferably 0≦Gu≦4. Satisfying the above range improves designability.

The thickness ratio of the black colored layer and the matte layer is preferably 1 for the black colored layer and 1 or more for the matte layer. More preferably, the number of black colored layers is 1 and the number of matte layers is 2 or more, since the design is easily improved.

(Release liner)
The pressure-sensitive adhesive tape of the present invention may be provided with a release liner on the surface of the pressure-sensitive adhesive layer in order to protect the pressure-sensitive adhesive layer. As the release liner, a known release liner may be appropriately selected and used. A resin film subjected to release treatment is preferable because of its excellent smoothness. Among them, a release-treated polyester film having excellent heat resistance is preferable. The total thickness of the colored adhesive tape as used in the present invention means the thickness of the adhesive tape itself without the release liner.

The surface of these release liners is preferably provided with a release treated layer in order to impart easy peelability. The release treatment layer can be formed from various release treatment agents used for release liners of double-sided adhesive tapes. A peeling treatment agent or the like can be preferably used. Moreover, the release treatment layer may be formed by lamination or coating on the resin film.

The release force of the release liner may be appropriately adjusted according to the mode of use and the like. , is preferred because deformation of the double-sided pressure-sensitive adhesive tape can be easily suppressed when the release liner is peeled off. The release force can be measured by peeling a release liner or a 50 μm thick PET-backed pressure-sensitive adhesive layer at a speed of 0.3 to 10 m/min in a 180° direction.

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.
(Preparation of adhesive A)
n-butyl acrylate: 97.98 parts, acrylic acid: 2 parts, 4-hydroxybutyl acrylate: 0.02 parts, azobisisobutyronitrile: 0.2 parts as a polymerization initiator, ethyl acetate Solution polymerization was carried out in the solution at 80° C. for 8 hours to obtain an acrylic polymer with a weight average molecular weight of 900,000. The acrylic polymer: 100 parts, a polymerized rosin ester (trade name “D-135” manufactured by Arakawa Chemical Co., Ltd.): 5 parts, and a disproportionated rosin ester (trade name “KE-100” manufactured by Arakawa Chemical Co., Ltd.): 20 25 parts of petroleum resin (trade name “FTR6100”: 25 parts) and ethyl acetate were added to prepare an adhesive solution having a solid content of 40%. Furthermore, an isocyanate-based cross-linking agent (trade name “NC40” manufactured by DIC): 0.8 parts was added, and the mixture was uniformly mixed by stirring to prepare an adhesive A. The gel fraction was 20% and the storage elastic modulus at 25°C was 9 x ^104Pa .

(Adjustment of adhesive B)
n-butyl acrylate: 93.4 parts, acrylic acid: 3.5 parts, vinyl acetate: 3 parts, β-hydroxyethyl acrylate: 0.1 parts, azobisisobutyronitrile: 0.2 parts was used as a polymerization initiator, solution polymerization was carried out in an ethyl acetate solution at 80°C for 8 hours to obtain an acrylic polymer having a weight average molecular weight of 800,000. The acrylic polymer: 100 parts, polymerized rosin ester (trade name “D-135” manufactured by Arakawa Chemical Co., Ltd.): 10 parts, and disproportionated rosin ester (trade name “A-100” manufactured by Arakawa Chemical Co., Ltd.): 10 Part was added, and ethyl acetate was added to prepare an adhesive solution having a solid content of 38%. Further, 1.3 parts of an isocyanate-based cross-linking agent (trade name “NC40” manufactured by DIC) was added, and the mixture was uniformly mixed by stirring to prepare an adhesive B. The gel fraction was 45% and the storage modulus at 25°C was 10 ⁵ Pa.

(Adjustment of Adhesive C)
n-butyl acrylate: 97.98 parts, acrylic acid: 2 parts, 4-hydroxybutyl acrylate: 0.02 parts, azobisisobutyronitrile: 0.2 parts as a polymerization initiator, ethyl acetate Solution polymerization was carried out in the solution at 80° C. for 8 hours to obtain an acrylic polymer with a weight average molecular weight of 900,000. The acrylic polymer: 100 parts, a polymerized rosin ester (trade name “D-135” manufactured by Arakawa Chemical Co., Ltd.): 5 parts, and a disproportionated rosin ester (trade name “KE-100” manufactured by Arakawa Chemical Co., Ltd.): 20 25 parts of petroleum resin (trade name “FTR6100”: 25 parts) and ethyl acetate were added to prepare an adhesive solution having a solid content of 40%. Next, 10 parts of DIC's black colorant "DICTON Black AR8555" (carbon black content: 45% (solid content ratio), resin solid content concentration: 49%) was added and uniformly mixed with a stirrer. Further, 1.2 parts of an isocyanate-based cross-linking agent (trade name “NC40” manufactured by DIC) was added, and the mixture was uniformly mixed by stirring to prepare an adhesive C. The gel fraction was 20% and the storage elastic modulus at 25°C was 8 x ^104Pa .

(Adjustment of Adhesive D)
n-butyl acrylate: 93.4 parts, acrylic acid: 3.5 parts, vinyl acetate: 3 parts, β-hydroxyethyl acrylate: 0.1 parts, azobisisobutyronitrile: 0.2 parts was used as a polymerization initiator, solution polymerization was carried out in an ethyl acetate solution at 80°C for 8 hours to obtain an acrylic polymer having a weight average molecular weight of 450,000. The acrylic polymer: 100 parts, polymerized rosin ester (trade name “D-135” manufactured by Arakawa Chemical Co., Ltd.): 10 parts, and disproportionated rosin ester (trade name “A-100” manufactured by Arakawa Chemical Co., Ltd.): 10 Part was added, and ethyl acetate was added to prepare an adhesive solution having a solid content of 38%. Furthermore, an isocyanate-based cross-linking agent (trade name “NC40” manufactured by DIC): 0.5 parts was added, and the mixture was uniformly mixed by stirring to prepare an adhesive D. The gel fraction was 4.5% and the storage elastic modulus at 25°C was 4 x ^104Pa .

[Production of Black Ink A]
In a four-necked flask equipped with a stirrer, thermometer, reflux condenser and nitrogen gas inlet tube, the acid component of adipic acid/terephthalic acid = 50/50 and the number average molecular weight obtained from 3-methyl-1,5-pentanediol (hereinafter referred to as 256.3 parts of a polyester diol having an Mn of 2,000 and 36.5 parts of isophorone diisocyanate were charged and reacted at 90° C. for 15 hours under a nitrogen stream. Then, 5.0 parts of isophorone diamine, 2.2 parts of di-n-butylamine, 175 parts of toluene, 350 parts of methyl ethyl ketone and 175 parts of isopropylene alcohol are added and reacted at 40° C. for 3 hours under stirring to obtain a resin solid content. A polyester urethane resin A having a concentration of 30.0%, a Gardner viscosity UV (25° C.), an amine value of 0 and a mass average molecular weight (hereinafter referred to as Mw) of 67,000 was obtained. The tan δ peak temperature of the resulting resin was -8°C.

4 parts of "Carbon Special 250P" manufactured by Degussa, 40 parts of polyester urethane resin A (tan δ peak temperature = -8 ° C.), 23 parts of methyl ethyl ketone, 13 parts of toluene, 6 parts of ethyl acetate, 3 parts of N-propyl acetate and 3 parts of isopropyl alcohol are added and wet-dispersed in a sand mill for about 1 hour. A black ink A was prepared by adding 35 parts of V No. 20. The carbon black content in the black ink solid content was 25% by weight.

[Production of Black Ink B]
Black ink B was produced in the same manner as black ink A except that the amount of "Carbon Special 250P" manufactured by Degussa was changed from 4 parts to 8 parts. The carbon black content in the black ink solid content was 40% by weight.

[Production of Black Ink C]
Black ink C was produced in the same manner as black ink A except that the amount of "Carbon Special 250P" manufactured by Degussa was changed from 4 parts to 6 parts. The carbon black content in the black ink solid content was 33% by weight.

[Production of black ink D]
Black ink B except that the polyester urethane resin A was replaced with an acrylic resin (mass average molecular weight 45,000, Tan δ peak temperature 50 degrees, "Dianal BR116" manufactured by Mitsubishi Chemical Corporation, solid content 30% by weight) A black ink D was prepared in the same manner. The carbon black content in the black ink solids was 40% by weight.
[Production of black ink E]
Black ink E was prepared in the same manner as black ink A except that 4 parts of "Carbon Special 250P" manufactured by Degussa was replaced with "A1103" manufactured by Dainichiseika. The carbon black content in the black ink solids was 40% by weight.

[Production of matte ink A]
Matte ink in the same manner as black ink A except that instead of using Degussa's "Carbon Special 250P", Fuji Silysia Co., Ltd.'s "Sylysia 440" (untreated silica: average particle size by the coal counter method: 3.5 μm) was used. created an A.

[Production of matte ink B]
Instead of using Degussa's "Carbon Special 250P", use Fuji Silysia's "Silophobic 704" (silane coupling treatment: average particle size 3.5 μm by the coal counter method), and the amount of 4 parts Matte Ink B was prepared in the same manner as Black Ink A except that 8 parts were used instead of .

[Production of matte ink C]
Instead of using Degussa's "Carbon Special 250P", use Fuji Silysia's "Sylysia 440" (untreated silica: average particle size 3.5 μm by the call counter method), and change the blending amount from 4 parts to 8 A matte ink C was prepared in the same manner as the black ink A, except that the black ink was changed to .

[Production of matte ink D]
Instead of polyester urethane resin A, acrylic resin (mass average molecular weight 45,000, Tan δ peak temperature 50 degrees, "Dianal BR116" manufactured by Mitsubishi Chemical Corporation, solid content 30% by weight) was changed, and Degussa ""Carbon Special 250P" was not used, and "Sylysia 440" manufactured by Fuji Silysia Co., Ltd. (untreated silica: average particle size 3.5 μm by the call counter method) was used, and the amount was changed from 4 parts to 8 parts. A matte ink D was prepared in the same manner as the black ink A except for the above.

(Creation of colored base material)
(Black ink coated film A)
Polyimide film Kapton 30EN (thickness: 7.5 μm, tensile strength: 307 MPa) manufactured by Toray DuPont was gravure-coated with black ink A to a dry thickness of 2.0 μm, and dried at 100° C. for 1 minute.
Next, the colored layer was gravure-coated with matte ink A to a dry thickness of 1.0 μm, and dried at 100° C. for 1 minute.
Next, the matte ink B was gravure-coated on the colored layer and the matte layer side so that the dry thickness was 1.0 μm, dried at 100° C. for 1 minute, and aged at 40° C. for 1 day to form a black ink coated film A. got

(Black ink coated film B)
Black ink was used except that black ink B was used instead of black ink A, matte ink A with a dry thickness of 1.0 μm was used, and matte ink C with a dry thickness of 4.0 μm was used instead of matte ink B with a dry thickness of 1.0 μm. A black ink-coated film B was obtained in the same manner as the coated film A.

(Black ink coated film C)
Black ink was used except that black ink C was used instead of black ink A, matte ink A with a dry thickness of 1.0 μm was used, and matte ink C with a dry thickness of 4.0 μm was used instead of matte ink B with a dry thickness of 1.0 μm. A black ink-coated film C was obtained in the same manner as the coated film A.

(Black ink coated film D)
A polyimide film with a thickness of 3.0 μm was used instead of Dupont Toray polyimide film Kapton 30EN, a black ink C with a dry thickness of 1.5 μm was used instead of black ink A with a dry thickness of 2.0 μm, and a dry thickness of 1.0 μm was used. A black ink-coated film D was obtained in the same manner as the black ink-coated film A except that the matte ink A and the matte ink B having a dry thickness of 1.0 μm were replaced with the matte ink C having a dry thickness of 2.5 μm.

(Black ink coat fill E)
DuPont Toray polyimide film Kapton 20EN (thickness: 5.0 μm, tensile strength: 311 MPa) was used instead of DuPont Toray polyimide film Kapton 30EN,
Black ink-coated film E was prepared in the same manner as black ink-coated film A except that matte ink A with a dry thickness of 1.0 μm and matte ink B with a dry thickness of 1.0 μm were replaced with matte ink A with a dry thickness of 2.0 μm. Obtained.

(Black ink coated film F)
DuPont Toray polyimide film Kapton 20EN (thickness: 5.0 μm, tensile strength: 311 MPa) was used instead of Toray DuPont polyimide film Kapton 30EN, and dry thickness 1.5 μm instead of black ink A with a dry thickness of 2.0 μm. Using black ink D of
Black ink-coated film F was prepared in the same manner as black ink-coated film A except that matte ink A with a dry thickness of 1.0 μm and matte ink D with a dry thickness of 2.0 μm were used instead of matte ink B with a dry thickness of 1.0 μm. Obtained.

(Black ink coated film G)
DuPont Toray polyimide film Kapton 20EN (thickness: 5.0 μm, tensile strength: 311 MPa) was used instead of DuPont Toray polyimide film Kapton 30EN,
Black ink E with a dry thickness of 1.5 μm was used instead of black ink A with a dry thickness of 2.0 μm, and matte ink A with a dry thickness of 1.0 μm and matte ink B with a dry thickness of 1.0 μm were replaced with a dry thickness of 1.0 μm. A black ink-coated film G was obtained in the same manner as the black ink-coated film A except that the 0 μm matte ink A was used.

(Black ink coated film H)
The dry thickness of black ink A was changed from 2.0 μm to 1.0 μm, and instead of matte ink A with a dry thickness of 1.0 μm and matte ink B with a dry thickness of 1.0 μm, matte ink A with a dry thickness of 2.0 μm was used. A black ink-coated film H was obtained in the same manner as the black ink-coated film A, except that it was used.

(Black ink coated film I)
The dry thickness of black ink A was changed from 2.0 μm to 1.5 μm, and instead of matte ink A with a dry thickness of 1.0 μm and matte ink B with a dry thickness of 1.0 μm, matte ink C with a dry thickness of 3.0 μm was used. A black ink-coated film I was obtained in the same manner as the black ink-coated film A, except that it was used.

(Black ink coated film J)
The dry thickness of black ink A was changed from 2.0 μm to 3.0 μm, and instead of matte ink A with a dry thickness of 1.0 μm and matte ink B with a dry thickness of 1.0 μm, matte ink C with a dry thickness of 0.5 μm was used. A black ink-coated film J was obtained in the same manner as the black ink-coated film A except that it was used.

(Example 1)
First, the adhesive A was applied to a release film (“PET38×1A3” manufactured by Nippa Co., Ltd.) with a roll coater so that the dry thickness was 2.0 μm, dried at 100° C. for 1 minute, and applied as a base material. It was attached to the polyimide surface of a black ink-coated film A and aged at 40° C. for 2 days.

(Example 2)
A pressure-sensitive adhesive tape of Example 2 was obtained in the same manner as in Example 1, except that the black ink-coated film B was used instead of the black ink-coated film A.

(Example 3)
An adhesive tape of Example 3 was obtained in the same manner as in Example 1 except that black ink coated film C was used instead of black ink coated film A and adhesive B was used instead of adhesive A.

(Example 4)
An adhesive tape of Example 4 was obtained in the same manner as in Example 1 except that black ink coated film D was used instead of black ink coated film A and adhesive B was used instead of adhesive A.

(Example 5)
An adhesive tape of Example 5 was obtained in the same manner as in Example 1 except that black ink coated film E was used instead of black ink coated film A and adhesive C was used instead of adhesive A.

(Example 6)
The adhesive of Example 6 in the same manner as in Example 1 except that black ink coated film F was used instead of black ink coated film A, adhesive C was used instead of adhesive A, and the dry thickness was changed from 2 μm to 4 μm. got the tape.

( Example 7 )
A pressure-sensitive adhesive tape of Example 7 was obtained in the same manner as in Example 1 except that black ink-coated film E was used instead of black ink-coated film A.

(Comparative example 2)
Adhesion of Comparative Example 1 in the same manner as in Example 1 except that black ink coated film H was used instead of black ink coated film A, adhesive B was used instead of adhesive A, and the dry thickness was changed from 2 μm to 4 μm. got the tape.

(Comparative Example 3)
A pressure-sensitive adhesive tape of Comparative Example 1 was obtained in the same manner as in Example 1, except that the pressure-sensitive adhesive D was used instead of the pressure-sensitive adhesive A.

(Comparative Example 4)
A pressure-sensitive adhesive tape of Comparative Example 1 was obtained in the same manner as in Example 1, except that the pressure-sensitive adhesive D was used instead of the pressure-sensitive adhesive A and the dry thickness was changed from 2 μm to 4 μm.

The adhesive tapes of Examples and Comparative Examples were evaluated for tape thickness, gloss (60°), L*a*b* defined by the L*a*b* color system, holding power, and transmittance. The results are shown in Tables 1 and 2.

(Thickness measurement)
The thickness was measured in units of 0.1 μm using “Digimicro MF-501”, “MCF-101” and “MS-31G” manufactured by Nikon Corporation.

(Measurement of glossiness (gloss: Gu))
Using "MINOLTA Multi-Gloss 268" manufactured by KONICA MINOLTA, the glossiness Gu measured at a set angle of 60° was measured according to JIS Z8741.

(Measurement of L*, a*, b*)
L*, a*, b* defined by the L*a*b* color system according to JIS Z 8781 with a measurement standard of 10° C spectrum using KONICA MINOLTA's "SPECTROPHOTOMETER CM-5" was measured.

(Evaluation of holding force)
The adhesive tape was cut into a width of 25 mm, and a load of 150 g (25 mm × 25 mm) was applied in the vertical direction according to JIS Z0237.

(Total light transmittance)
The total light transmittance Tt of the black polyimide adhesive tape was measured according to JIS K7105 with "HR-100" manufactured by Murakami Color Research Laboratory.

Claims (6)

Coloring having a polyimide film layer with a thickness of 1.0-15.0 μm, a black colored layer with a thickness of 1.5-3.0 μm, and a matte layer with a thickness of 1.0-5.0 μm It has a substrate and an adhesive layer, has CIE color values (L*, a*, b*) within the following ranges, the adhesive layer is made of an acrylic adhesive, and the adhesive layer has a gel fraction of 5. 5.0-30.0 μm thick black polyimide adhesive tape, characterized by ˜50%.
18 ≤ L* ≤ 36
-3 ≤ a* ≤ 3
-3 ≤ b* ≤ 3 2. The pressure-sensitive adhesive tape according to claim 1, wherein the glossiness Gu measured at a set angle of 60[deg.] according to JIS Z8741 is within the following range.
0≦Gu≦10 3. The pressure-sensitive adhesive tape according to claim 1, wherein the colored substrate has a light transmittance of 0.1 to 10%. 4. The method according to any one of claims 1 to 3, wherein the black colored layer is made of black colored ink containing carbon black as a coloring material, and the content of carbon black is 10 to 70% by mass based on the solid content of the colored ink. Adhesive tape as described. The pressure-sensitive adhesive tape according to any one of claims 1 to 4, wherein the acrylic pressure-sensitive adhesive contains an acrylic polymer having a molecular weight (Mw) of 500,000 to 1,200,000. For a test piece cut to a width of 25 mm, according to JISZ-0237, a load of 100 g (25 mm × 25 mm) is applied in the vertical direction, and the displacement distance is 2.0 mm or less when left in an atmosphere of 150 ° C for 24 hours. The adhesive tape according to any one of claims 1-5.