JP5896208B2 - Colored film and colored adhesive tape - Google Patents

Description

  The present invention relates to a colored film and a colored adhesive tape provided with a colored layer made of colored ink on a support.

  Colored films and colored adhesive tapes are used in various industrial fields for purposes such as decoration, display, concealment, reflection, and light shielding. In particular, parts such as personal computers, digital video cameras, and electronic notebooks, mobile phones, PHS, smartphones, game machines, electronic books, and other portable electronic terminals are particularly demanded for downsizing and thinning. In addition to fixing and protecting parts, it also has the effects of black shading, improved brightness due to white coloring, blinding of appearance defects (unevenness, point defects, etc.) and improved appearance. Since the number of parts to be used is reduced, various colored adhesive tapes are used.

  As a colored pressure-sensitive adhesive tape used for a portable electronic terminal or the like, for example, a light-shielding pressure-sensitive adhesive tape using a colored ink containing polyester urethane ink as a binder resin as a light-shielding layer is disclosed (see Patent Document 1). The light-shielding pressure-sensitive adhesive tape has suitable resilience resistance and reworkability without using a halogenated vinyl acetate resin ink. However, when the colored layer is used as the outermost layer, sebum and fingerprints are likely to adhere, and there is a problem that sebum and fingerprints adhering onto the dark light-shielding layer are easily noticeable.

  Further, it is a decorative sheet in which a transparent resin layer and a surface protective layer having a surface roughness Ra of 0.1 to 0.3 μm are provided in this order on a transparent sheet in the form of a colored base sheet, the surface protective layer being an average particle A silicone-modified ionizing radiation curable resin containing silica particles having a diameter of 3 to 5 μm is disclosed (Patent Document 2). Since the colored film has a multilayer structure, is expensive, and is cured by ionizing radiation, it cannot be used because a curl is generated when the support is thin.

JP 2010-53240 A JP 2009-291196 A

  The problem to be solved by the present invention is to provide a colored film and a colored adhesive tape having excellent fingerprint resistance at low cost.

  As a result of intensive studies to achieve the above object, the present inventors have found that the object of the present invention can be achieved by using a colored ink containing a specific amount of silica particles having a specific average particle diameter. It came to complete.

That is, the present invention is a colored film in which a colored layer made of a colored ink is provided on a support, wherein the colored layer is made of a colored ink containing a binder resin, a coloring material, and silica particles, The average particle diameter by the counter method is 2 to 6 μm, the content of silica particles is 10 to 80 parts by mass with respect to 100 parts by mass of the binder resin in the colored ink, and the average particle diameter of the silica particles is the colored layer. The present invention provides a colored film and a colored pressure-sensitive adhesive tape characterized by being larger than the film thickness of the ink film.

  The colored film and colored adhesive tape of the present invention are excellent in fingerprint resistance and sebum and fingerprints are hardly noticeable, so that a good appearance can be maintained.

It is the schematic which shows an example of the colored adhesive tape using the colored film of this invention. It is the schematic which shows an example of the colored adhesive tape using the colored film of this invention. It is an example (black film A) of the cross-sectional microscope picture of the colored film of this invention.

[Support]
As a support used for the colored film and the colored adhesive tape of the present invention, various resin films, metals, and composite films of metals and resin films can be used as appropriate. Examples of the resin film include a polyester film, a polyethylene film, a polypropylene film, a polystyrene film, and a polyimide film. Examples of the metal include copper foil, aluminum foil, nickel foil, iron foil, and alloy foil. Examples of the composite film of metal and resin film include those obtained by laminating the resin film and metal. Among these, a polyester film and a polyimide film excellent in strength and insulating properties are preferable. Although the thickness of a support body is not specifically limited, 1-75 micrometers is preferable, More preferably, it is 4-38 micrometers. By being in this range, it is easy to achieve both mechanical strength and thinness when protecting the magnetic sheet.

  Various colored pigments may be mixed in the resin film in order to impart concealability and reflectivity.

[Colored layer]
The colored layer in the colored film and colored adhesive tape of the present invention is a layer made of colored ink. The colored layer is a layer in which silica particles and particles such as resin beads added as necessary are fixed by an ink film formed from a binder resin of colored ink. In the present invention, favorable fingerprint resistance can be achieved by making the average particle diameter of the silica particles in the colored layer by the Coulter counter method larger than the thickness of the ink film of the colored layer. The relationship between the average particle diameter a of the silica particles by the Coulter counter method and the thickness b of the ink film of the colored layer is a> b, preferably a−b = 0.5 to 5.0 μm, more preferably It is preferable that a−b = 1.0 to 3.0 μm. The thickness of the ink film of the colored layer as shown in FIG. 3 is measured by cross-sectional observation with a microscope. The thickness of the ink film of the colored layer is the thickness of the portion without silica.
The thickness of the ink film of the colored layer is not particularly limited, but is preferably 0.5 μm to 6 μm, more preferably 1 μm to 5 μm, and most preferably 1.5 μm to 4 μm.

  The surface roughness Ra of the colored layer is not particularly limited, but is preferably 0.35 to 1.00 μm. Further, this is preferably 0.4 to 0.9 μm, and most preferably 0.45 to 0.7 μm. The surface roughness Ra was measured with a stylus type surface roughness measuring instrument having a stylus tip radius of 5 μm and a stylus tip taper angle of 90 °, a measuring speed of 0.3 mm / s, a reference length of 5 mm, and a measuring force of 4 mN. The arithmetic mean roughness (Ra) when the surface contour curve is measured under the condition of a cutoff value of 0.8 mm.

  As the stylus type surface roughness measuring instrument, for example, Surfcom 575A manufactured by Tokyo Seimitsu Co., Ltd., P-11 manufactured by KEL Tencor Co., SE3500 manufactured by Kosaka Laboratory, or the like can be used. The measurement of the surface contour curve is based on JIS-B0651, and Ra and Rt are defined in JIS-B0601. The above range uses Surfcom 575A manufactured by Tokyo Seimitsu Co., Ltd., a reference length of 5 mm, a tip radius of the stylus of 5 μm, a tip angle of the stylus of 90 °, a measuring force of 4 mN, a cut-off value of 0.8 mm, a measuring speed of 0.8 mm. It is a value measured under the condition of 3 mm / s.

(Ink composition)
The colored ink used for the colored film and the colored adhesive tape of the present invention contains a binder resin, a coloring material, and silica particles.

(Binder resin)
As the composition of the binder resin, polyester, acrylic, urethane, etc. can be used. Among them, polyester urethane-based resin does not contain a halogen, and even if it is a thin support, curling is unlikely to occur. preferable. Moreover, it is preferable that the polyester urethane type resin has the glass transition temperature of -30-30 degreeC. By using the polyester urethane-based resin, there is little curl even if it is applied to a thin film, even if it is an ultra-thin adhesive tape configuration, and it is strong even for thin resin films that are difficult to easily adhere to such as corona treatment. Adhesion and good adhesion and reworkability can be realized. More preferably, it is -25 degreeC-10 degreeC, Most preferably, it is -20 degreeC-0 degreeC. The glass transition temperature of the polyester urethane resin is a peak temperature of tan δ of the dynamic viscoelastic spectrum at a frequency of 1 Hz measured as follows.

(Measurement of dynamic viscoelasticity of polyester urethane resin)
Polyester urethane resin is formed to a thickness of 50 μm with a bar coater. Next, from a specimen cut to a sample length of 20 mm (sample length of 20 mm, film thickness of 50 μm) using a viscoelasticity tester from −150 ° C. to 250 ° C. at a frequency of 1 Hz and a temperature increase time of 3 ° C./1 minute. The storage elastic modulus (G ′) and the loss elastic modulus (G ″) are measured. The loss tangent tan δ is calculated by the following calculation formula.
Loss tangent tan δ = G ″ / G ′
Examples of the viscoelasticity tester include DMS210, DMS220, and DMS6100 manufactured by Seiko Instruments Inc.

  The polyurethane resin used in the present invention is a resin obtained by a condensation polymerization reaction of a diisocyanate compound, a high molecular polyol compound, a low molecular weight chain extender, etc., and has many urethane bonds in the molecule.

  Specific examples of the diisocyanate compound suitably used for the polyurethane resin include, for example, methylene diisocyanate, isopropylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, and dimer acid. A chain aliphatic diisocyanate such as dimerisocyanate in which a carboxyl group is substituted with an isocyanate group; cyclohexane-1,4-diisocyanate, isophorone diisocyanate, dicyclohexylmethane-4,4′-diisocyanate, 1,3-di (isocyanatomethyl) cyclohexane, Cycloaliphatic diisocyanates such as methylcyclohexane diisocyanate; 4,4′-diphenyldimethylmethane diisocyanate Dialkyldiphenylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate such as 4,4′-diphenyltetramethylmethane diisocyanate, 1,5-naphthylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 4, Aromatic diisocyanates such as 4′-dibenzyl isocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, m-tetramethylxylylene diisocyanate; amino acid diisocyanates such as lysine diisocyanate, etc. Can be mentioned. These polyisocyanate compounds including these diisocyanate compounds are used alone or in admixture of two or more.

  As the polymer polyol, various known ones generally known as a polymer polyol component of a polyurethane resin can be used. For example, polyether polyols such as polymers or copolymers of ethylene oxide, propylene oxide, tetrahydrofuran, etc .; ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3 -Butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, octanediol, 1,4-butynediol, 1,4- Various saturated and unsaturated low molecular weight glycols such as cyclohexane-dimethanol and dipropylene glycol, adipic acid, maleic acid, fumaric acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, oxalic acid, malonic acid, Glutaric acid, pimelic acid, a Polyester polyols obtained by dehydration condensation with dibasic acids such as rhine acid, sebacic acid and suberic acid or acid anhydrides and dimer acids corresponding thereto; polyester polyols obtained by ring opening of cyclic ester compounds Other polycarbonate polyols; polybutadiene polyols; glycols obtained by adding ethylene oxide or polypropylene oxide to bisphenol A, and various known polymer polyols generally used for the production of polyurethane. Of these, a product obtained by dehydrating and condensing an aromatic dicarboxylic acid and a diol is preferable. Among them, a product obtained by dehydrating and condensing a mixture of adipic acid and terephthalic acid and 3-methyl-1,5-pentanediol can be obtained.

  The polyol has a number average molecular weight of 500 to 10,000, preferably 1000 to 6,000. When the number average molecular weight is 500 or more, the solubility is good and the printability is easily improved, and when it is 10,000 or less, the drying property and the blocking resistance are easily improved.

  Examples of the chain extender include various known diamines and glycols. Examples of diamines include ethylenediamine, propylenediamine, hexamethylenediamine, triethylenetetramine, diethylenetriamine, isophoronediamine, dicyclohexylmethane-4,4′-diamine, 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di- Diamines having a hydroxyl group in the molecule such as 2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, di-2-hydroxypropylethylenediamine, and the carboxyl group of dimer acid are converted to amino groups. A typical example is dimer diamine.

  Furthermore, a reaction terminator can be used in the urethanization reaction. Examples of such a reaction terminator include dialkylamines such as di-n-butylamine, aromatic amines such as benzylamine and dibenzylamine, alkanolamines such as diethanolamine, and alcohols such as techanol and isopropanol alcohol. And amino alcohols such as monoethanolamine.

  There is no restriction | limiting in particular about the method of manufacturing a polyurethane resin, What is necessary is just to manufacture according to the method similar to the manufacturing method of a general polyester urethane urea resin. For example, a diisocyanate component and a polyol component are reacted at an equivalent ratio of excess isocyanate groups to form a prepolymer of both terminal isocyanate groups, which are then reacted with a chain extender and optionally a reaction terminator in a suitable solvent. However, the compounds can also be reacted together.

  The average molecular weight of the polyurethane resin is not particularly limited, and is usually about 5,000 to 200,000, preferably about 15,000 to 80,000.

(Coloring material)
As the coloring material, known and commonly used pigments and dyes can be used. For example, carbon black for black, titanium oxide, calcium carbonate, barium sulfate for white, yellow iron oxide for yellow, red iron for red, cyanine blue for blue, aluminum powder for silver, In the case of pearl, mica titanium powder is preferable from the viewpoint of weather resistance, heat resistance, and dispersibility in ink resin. Of these, carbon black is preferable because of its excellent concealability.

  The carbon black is particularly preferably acid-treated carbon black. By using acid-treated carbon, it has excellent insulating properties.

  What is necessary is just to adjust suitably according to a use etc. as addition amount of a coloring material, and 10 to 60% in the ink solid content containing a coloring material is preferable. More preferably, it is 20 to 40%. If it is 10% or more, concealment properties are suitably exhibited, and if it is 60% or less, the dispersion is good.

(Silica particles)
The average particle diameter a of the silica particles by the Coulter counter method is 2.0 μm to 6.0 μm. More preferably, it is 2.3 micrometers-5.0 micrometers, Most preferably, it is 3.0 micrometers-4.5 micrometers. When the average particle diameter of the silica particles is within the above range, fingerprint resistance, adhesion and scratch properties can be highly compatible.

Content of a silica particle is 10-80 mass parts with respect to 100 mass parts of binder resin. More preferably, it is 20-75 mass parts, Most preferably, it is 30-60 mass parts. When it is in the above range, both fingerprint resistance and adhesion can be achieved at a high level.

As the silica particles, various types of silica such as precipitated silica, gel silica, dry silica, colloidal silica and the like can be used. Of these, precipitated silica and monodispersed colloidal silica are preferred.
The silica surface may be subjected to various treatments such as hydrophobic treatment (surface treatment by chemically bonding silane coupling treatment or silicone oil), organic treatment (silica surface treatment with wax), inorganic treatment, and the like. Among them, those subjected to hydrophobic treatment are preferable because they are particularly excellent in fingerprint resistance, and those subjected to silane coupling treatment are particularly preferable. Examples of commercially available silica particles that have been subjected to hydrophobic treatment include “Silo Hovic 704” manufactured by Fuji Silysia Co., Ltd. and “Nip Seal SS-50B” manufactured by Tosoh Silica Co., Ltd.

(Spherical filler)
By using a spherical filler for the colored ink used for the colored film and the colored tape of the present invention, the fingerprint resistance can be further improved. As the spherical filler, silicone resin beads, acrylic resin beads, urethane resin beads, acrylic urethane resin beads, nylon resin beads, melamine resin beads, silica beads, glass beads and the like are used. Among these, silicone resin beads are preferable because they have a high effect of improving fingerprint resistance.

The average particle diameter of the spherical filler by the Coulter counter method is preferably 2 μm to 12 μm from the viewpoint of fingerprint resistance. More preferably, it is 3 micrometers-10 micrometers, Most preferably, they are 4 micrometers-8 micrometers.
Further, it is desirable from the viewpoint of fingerprint resistance and scratch resistance that the average particle diameter of the hydrophobically treated silica and the spherical filler by the Coulter counter method is hydrophobic treated silica particles <spherical filler.

  Although it does not specifically limit as addition amount of a spherical filler, 1-60 mass parts is preferable with respect to 100 mass parts of binder resins. More preferably, it is 5-50 mass parts, Most preferably, it is 10-30 mass parts.

  Moreover, you may contain other various additives as needed. Examples of various additives include an anti-aging agent, a light stabilizer, and an anti-blocking agent.

  Further, it is desirable to use a dispersant and an anti-settling agent as additives. The dispersibility of the pigment can be maintained and the stability of the ink can be improved. The addition amount of the dispersant and the anti-settling agent is preferably 0.05 to 10% by mass with respect to the ink solid content.

  As the solvent to be used, a solvent which is usually known as a solvent for printing ink can be mentioned. For example, aromatic solvents such as toluene and xylene, alcohol solvents such as methanol, ethanol, isopropanol and n-propanol, ketone solvents such as acetone, methyl ethyl ketone and methyl isobutyl ketone, ester solvents such as ethyl acetate and butyl acetate, Glycols such as propylene glycol monomethyl ether are raised, and these can be used alone or in a mixture of two or more.

  The colored ink used for the colored film and the colored tape of the present invention can improve physical properties such as adhesion to the substrate by adding a curing agent. As the curing agent, an aliphatic or alicyclic isocyanate is usually used. Examples of the aliphatic or alicyclic isocyanate include hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, trimethylhexamethylene isocyanate, 1,6,11-undecane triisocyanate, lysine diisocyanate, lysine ester triisocyanate, 1,8-diisocyanate-4. -Isocyanatomethyloctane, 1,3,6-hexamethylene triisocyanate, bicycloheptane triisocyanate are used. Further, trimers of these isocyanates can be preferably used, and among them, diisocyanate adducts, biurets, and nurates are preferable. Among them, hexamethylene diisocyanate or isophorone diisocyanate adduct, biuret, or nurate is particularly preferable. A hardening | curing agent may be added independently and may add 2 or more types. As addition amount of a hardening | curing agent, it is preferable that it is 1-50 mass% with respect to ink solid content.

[Colored film]
The colored film of the present invention is obtained by providing a colored layer made of colored ink on a support. The colored layer can be provided by coating the support by various coating methods such as a gravure coater and a roll coater. Since the colored film of the present invention is excellent in fingerprint resistance, it is difficult to attach a fingerprint even when touched with a finger, and the appearance and design are excellent.

  The colored layer of the colored film is preferable because a part of the surface of the silica particle is exposed on the surface of the colored layer, so that the effect of fingerprint resistance can be easily obtained. For this reason, it is easy to cause silica particles to be deposited on the surface of the colored layer by containing a large amount of silica particles in the colored ink, and the average particle size of the silica particles in the colored ink used for the colored layer is the ink film of the colored layer. The ink film is preferably formed so as to be larger than the thickness of the ink film.

[Adhesive layer]
Although the thickness of the adhesive layer of the colored adhesive tape of this invention is not specifically limited, It is preferable that they are 0.5 micrometer-50 micrometers. More preferably, it is 3 micrometers-30 micrometers. Most preferably, it is 5 μm to 20 μm. By being in the above-mentioned range, fingerprint resistance and adhesiveness are both highly compatible.

  The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer of the colored pressure-sensitive adhesive tape of the present invention is not particularly limited. For example, an acrylic pressure-sensitive adhesive, a rubber pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a urethane pressure-sensitive adhesive, a polyester pressure-sensitive adhesive, Appropriately selected from known adhesives such as styrene-diene block copolymer adhesives, vinyl alkyl ether adhesives, polyamide adhesives, fluorine adhesives, improved creep characteristics adhesives, and radiation curable adhesives. Can be used. An adhesive can be used individually or in combination of 2 or more types.

  As the pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive can be preferably used because it has high adhesion reliability. The acrylic pressure-sensitive adhesive has an acrylic polymer as a pressure-sensitive adhesive component or main ingredient and, as necessary, an appropriate agent such as a crosslinking agent, a tackifier, a softener, a plasticizer, a filler, an anti-aging agent, or a colorant. Additives are included. Acrylic polymer is a polymer that has (meth) acrylic acid alkyl ester as the main component of monomer and can be copolymerized with (meth) alkyl ester as needed (copolymerizable monomer) Body). Examples of the (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, (meth) Isobutyl acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-Methylhexyl 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, (me ) Tetradecyl acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate (meta) ) Acrylic acid C1-20 alkyl ester [preferably (meth) acrylic acid C4-18 alkyl (straight or branched alkyl) ester] and the like. The (meth) acrylic acid alkyl ester can be appropriately selected according to the intended tackiness and the like. The (meth) acrylic acid alkyl ester can be used alone or in combination of two or more. What contains 30% or more of butyl acrylate is preferable because of excellent adhesion and heat resistance.

  Examples of the copolymerizable monomer 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 vinyl sulfonate; 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 Contains hydroxyl groups such as glycerin dimethacrylate Monomers; amino group-containing monomers such as aminoethyl (meth) acrylate and (meth) acryloylmorpholine; imide group-containing monomers such as cyclohexylmaleimide and isopropylmaleimide; glycidyl (meth) acrylate and (meth) acrylic Epoxy group-containing monomers such as methyl glycidyl acid; isocyanate group-containing monomers such as 2-methacryloyloxyethyl isocyanate, triethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, ethylene glycol di (meta ) Acrylate, tetraethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, Pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, a polyfunctional copolymerizable monomer (polyfunctional monomer) such as divinylbenzene, and the like. A copolymerizable monomer can be used individually or in combination of 2 or more types. As the copolymerizable monomer, a modifying monomer having a functional group such as a carboxyl group can be suitably used. What contains 0.5-4.0% of acrylic acid is preferable since it is excellent in adhesiveness and heat resistance.

  The mass average molecular weight (Mw) of the acrylic polymer is preferably 500,000 to 1,200,000. More preferably, it is 500,000 to 1,000,000. By being in the said range, even if it is a thin film, it is easy to express 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 tackifier resin in order to improve the adhesive strength of the adhesive layer. In addition, by adding these tackifying resins, it is possible to increase the tensile strength and tensile rupture strength, so depending on the acrylic copolymer used, by appropriately adding a tackifying resin, the tensile strength and The tensile breaking strength can be adjusted. Examples of the tackifying resin added to the pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive tape of the present invention include rosin resins such as rosin and rosin ester compounds; terpene resins such as diterpene polymers and α-pinene-phenol copolymers. A petroleum resin such as an aliphatic (C5) or aromatic (C9); a styrene resin, a phenol resin, a xylene resin, and the like. In particular, in a pressure-sensitive adhesive composition using an acrylic copolymer having n-butyl (meth) acrylate as a main monomer component, a rosin-based resin and a styrene-based resin are used to achieve a thin and compatible adhesive force and heat resistance. Are preferably used in combination.

  In order to increase the initial adhesive force, 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 normal temperature include liquid resins of the above-described tackifying resin that is solid at normal temperature, and low molecular weight liquid rubbers such as process oil, polyester plasticizer, and polybutene. A terpene phenol resin is particularly preferable. Commercially available products include YP-90L manufactured by Yasuhara Chemical. The addition amount of the tackifying resin is preferably 1 to 20 parts by mass with respect to 100 parts by mass of the acrylic copolymer.

  As addition amount of tackifying resin, it is preferable to add 10-70 mass parts with respect to 100 mass parts of acrylic copolymers. More preferably, it is 20-60 mass parts. Adhesive strength can be improved by adding a tackifying resin.

The gel fraction of the pressure-sensitive adhesive layer is not particularly limited, but it is preferably 5 to 50% because sufficient adhesiveness and heat resistance (holding power at high temperature) are easily exhibited even with a thin film. 10 to 40%, more preferably 13 to 35%. The gel fraction is expressed as a percentage with respect to the original mass by immersing the cured adhesive layer in toluene, measuring the mass after drying of the insoluble matter left after standing for 24 hours, and measuring the mass.
Gel fraction = [(mass after pressure-sensitive adhesive layer is immersed in toluene) / (weight of pressure-sensitive adhesive layer before immersion in toluene)] × 100

The storage elastic modulus of the pressure-sensitive adhesive layer is preferably 10 ⁴ to 4 × 10 ⁵ Pa at 25 ° C. at a frequency of 1 Hz. More preferably, it is 5 * 10 < ⁴ > -2 * 10 < ⁵ > Pa. By being in the said range, even if it is a thin adhesive layer, wettability (initial tack) and adhesive force are highly compatible easily.

  The acrylic polymer can be prepared by a conventional polymerization method such as a solution polymerization method, an emulsion polymerization method, or an ultraviolet irradiation polymerization method.

[Colored adhesive tape]
The colored pressure-sensitive adhesive tape of the present invention is a colored pressure-sensitive adhesive tape having a colored layer on at least one surface of a support and having a pressure-sensitive adhesive layer on the other surface. For example, FIG. 1 (single-sided tape: support) 2) (a structure having an adhesive layer on the other surface side) or FIG. 2 (single-sided tape: a structure having a colored layer on both sides of a support and an adhesive layer on one side) It is the structure of a single-sided adhesive tape. The colored layer on the side where the pressure-sensitive adhesive layer is provided in the configuration of FIG. 2 may be a colored layer made of the above-described colored ink or a colored layer made of any other colored ink. As described above, the colored pressure-sensitive adhesive tape of the present invention has high fingerprint resistance, and can be suitably used for protecting parts used in electronic devices, particularly portable electronic devices. Moreover, since the base material is colored, it is excellent in visibility and concealment. In addition, as long as it is within the thickness range of the colored 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 other functional layers are included between each layer. .

(Release liner)
In the pressure-sensitive adhesive tape of the present invention, a release liner may be provided on the surface of each pressure-sensitive adhesive layer in order to protect the pressure-sensitive adhesive layer. A known release liner may be appropriately selected and used as the release liner. A resin film that has been subjected to a release treatment is preferred because of its excellent smoothness. Of these, a polyester film having excellent heat resistance is preferably subjected to a release treatment. In addition, the total thickness of the colored adhesive tape as used in the field of this invention means the thickness of the adhesive tape itself which does not contain the said release liner.

  The surface of these release liners is preferably provided with a release treatment layer in order to impart easy peelability. The release treatment layer can be formed of various release treatment agents used for release liners for double-sided pressure-sensitive adhesive tapes. Examples of such release treatment agents include silicone-based, fluorine-based, and long-chain alkyl-based agents. A release treatment agent or the like can be preferably used. The release treatment layer may be formed on the above resin film by lamination or coating.

  The release force of the release liner may be appropriately adjusted according to the use mode and the like, but the release force for the pressure-sensitive adhesive layer is 0.01 to 2 N / 20 mm, preferably 0.05 to 0.15 N / 20 mm. When peeling the release liner, it is preferable because deformation of the double-sided pressure-sensitive adhesive tape is easily suppressed. The peeling force can be measured by peeling a release liner or a 50 μm thick PET-backed pressure-sensitive adhesive layer in a 180 ° direction at a speed of 0.3 to 10 m / min.

  The pressure-sensitive adhesive tape of the present invention can be suitably applied to the protection and design imparting of members that are required to have fingerprint resistance. Among these, the colored pressure-sensitive adhesive tape of the present invention is thin and excellent in fingerprint resistance and concealment, and therefore can be particularly suitably used for protecting a heat radiating sheet and a magnetic sheet.

(Usage for fixing heat dissipation sheet)
By installing the heat-dissipating sheet in a local high-temperature part, the heat-dissipating sheet dissipates heat to the entire surface of the electronic device, thereby solving a so-called hot spot. There are two types of graphite sheets used for the heat dissipation sheet: artificial graphite sheets and natural graphite sheets. As the artificial graphite sheet, there is a pyrolytic graphite sheet obtained by pyrolyzing an organic film such as a polyimide film in a high-temperature inert gas atmosphere. In addition, there is a natural graphite sheet in which natural graphite is acid-treated and then heated and expanded into graphite powder. As the graphite sheet used for the heat dissipation sheet, an artificial graphite sheet with less wrinkles is preferably used because heat dissipation is better when there are fewer wrinkles. The thickness of the graphite sheet used for the heat radiating sheet is preferably 10 to 100 μm, and more preferably 15 to 50 μm. By setting the thickness within this range, it can be suitably used for a thin portable electronic terminal device. Since these graphite sheets are very brittle, an adhesive tape is used to protect them.

  By laminating with the colored adhesive tape of the present invention, the thermal resistance of the tape can be reduced and the thermal conductivity in the thickness direction can be improved, so that the heat dissipation can be improved. Thinning is also possible. Furthermore, since the pressure-sensitive adhesive tape of the present invention is excellent in concealability, it is possible to make it difficult to see unevenness in the appearance of the heat dissipation sheet, and to improve the productivity of the heat dissipation sheet.

(Usage for fixing magnetic sheet)
The magnetic sheet is affixed to places where electromagnetic waves are to be blocked, such as the inner surface of the casing of electronic devices and the outer surfaces of various electronic components, thereby preventing external electromagnetic waves from penetrating into the electronic device or inside the electronic device. It is possible to prevent electromagnetic waves from leaking from the outside. Magnetic sheets are Ni-based ferrite magnetic powder, Mg-based ferrite magnetic powder, Mn-based ferrite magnetic powder, Ba-based ferrite magnetic powder, Sr-based ferrite magnetic powder, Fe-Si alloy powder, Fe-Ni alloy powder. , Fe-Co alloy powder, Fe-Si-Al alloy powder, Fe-Si-Cr alloy powder, iron powder, Fe-based amorphous, Co-based amorphous, Fe-based nanocrystal, etc. Easy to demonstrate magnetic performance. Since these magnetic sheets are very brittle, an adhesive tape is used to protect them, but even if the magnetic sheet is thickened by protecting with the adhesive tape of the present invention, a composite (bonded product of magnetic sheet and adhesive tape) ) As a thin film, and can impart fingerprint resistance.

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In addition, the part displayed below is a mass part.
[Production example of polyurethane]
(Polyurethane resin A)
A number average molecular weight obtained from an acid component of adipic acid / terephthalic acid = 50/50 and 3-methyl-1,5-pentanediol (hereinafter referred to as “four-flask” equipped with a stirrer, thermometer, reflux condenser and nitrogen gas introduction tube) 192.9 parts of a 2,000 polyester polyol (referred to as Mn), 15.8 parts of 1,4-butanediol and 77.9 parts of isophorone diisocyanate were charged and reacted at 90 ° C. for 15 hours under a nitrogen stream. Next, 11.0 parts of isophorone diamine, 2.4 parts of di-n-butylamine and 700 parts of methyl ethyl ketone were added, and the mixture was reacted at 50 ° C. for 4 hours under a stirring frame. The resin solid content concentration was 30.0%, Gardner viscosity U ( 25 ° C.), an amine value = 0, and a polyurethane resin A having a mass average molecular weight (hereinafter referred to as Mw) of 30,000 was obtained.

[Black ink production example]
(Black ink A)
10 parts of Degussa's “Special Black 250” (acidic carbon), 5 parts of “Silo Hovic 704” (Silane coupling treatment: average particle size of 3.5 μm by Coulter counter method), Momentive Performance 2 parts of “Tospearl 2000B” manufactured by Materials (spherical silicone resin beads: average particle diameter of 6 μm by Coulter counter method), 1 part of “Solspers 24000GR” manufactured by Lubrizol, polyurethane resin A ( Polyurethane resin) 55 parts (N.V. 30%), methyl ethyl ketone 13 parts, ethyl acetate 9 parts, isopropyl alcohol 5 parts, propylene glycol monomethyl ether 5 parts, and wet dispersed in a sand mill for about 1 hour Sumika Bayer Urethane Co., Ltd. 5 parts of a curing agent "Sumidule N3300", created a black ink A DIC Graphics Corporation diluent "NH-NT DC solvent" were added 40 parts.

(Black ink B)
12 parts Degussa "Special Black 250" (acidic carbon), 5 parts Fuji Silicia "Silo Hovic 704" (Silane coupling treatment: average particle size 3.5 µm by Coulter counter method), Momentive Performance -Polyurethane resin obtained in Production Example, 2 parts "Tospearl 145" manufactured by Materials (spherical silicone resin beads: average particle diameter 4.5 µm by Coulter counter method), 1 part "Solspers 24000GR" manufactured by Lubrizol 55 parts (N.V. 30%) of A (polyurethane resin), 13 parts of methyl ethyl ketone, 9 parts of ethyl acetate, 5 parts of isopropyl alcohol and 5 parts of propylene glycol monomethyl ether are added and wet dispersed in a sand mill for about 1 hour. Sumika Bayer Urethane Co., Ltd. 5 parts of a curing agent "Sumidule N3300", created the black ink B DIC Graphics Corporation diluent "NH-NT DC solvent" were added 40 parts.

(Black ink C)
12 parts Degussa “Special Black 250” (acidic carbon), 5 parts Tosoh Silica “Nipseal SS-50B” (hydrophobic treatment with silicone oil: average particle size 2.0 μm by Coulter counter method), Momentive -2 parts of "Tospearl 130" manufactured by Performance Materials (spherical silicone resin beads: average particle size of 3 µm by Coulter counter method), 1 part of "Solspers 24000GR" manufactured by Lubrizol, polyurethane resin obtained in production example 55 parts (N.V. 30%) of A (polyurethane resin), 13 parts of methyl ethyl ketone, 9 parts of ethyl acetate, 5 parts of isopropyl alcohol and 5 parts of propylene glycol monomethyl ether are added and wet dispersed in a sand mill for about 1 hour. Japanese polyurethane Work made hardener "Coronate HX" 7 parts to prepare a black ink C DIC Graphics Corporation diluent "NH-NT DC solvent" were added 40 parts.

(Black ink D)
Similar to the production example of black ink A using “Silicia 446” (organic treatment: average particle diameter of 3.5 μm by Coulter counter method) manufactured by Fuji Silysia Co., Ltd. instead of “Silohovic 704” of black ink A A black ink D was prepared.

(Black ink E)
The amount of black ink A “Silo Hovic 704” manufactured by Fuji Silysia Inc. was increased from 5 parts to 8 parts, and black ink E was prepared in the same manner as in the black ink A production example.

(Black ink F)
Instead of “Tospearl 2000B” of black ink A, “Techpolymer MB30X-5” (spherical cross-linked acrylic resin beads: average particle diameter by Coulter counter method) manufactured by Sekisui Plastics Co., Ltd. was used. Black ink F was prepared in the same manner as in the production example.

(Black ink G)
The black ink G was prepared in the same manner as in the black ink A production example without using the black ink A “Tospearl 2000B”.

(Black ink H)
Similar to the production example of black ink A using “Silicia 440” (untreated: average particle diameter of 3.5 μm by Coulter counter method) manufactured by Fuji Silysia Co., Ltd. instead of “Silo Hovic 704” of black ink A A black ink H was prepared.

(Black ink I)
Similar to the production example of black ink A using “Silicia 445” (inorganic treatment: average particle diameter of 3.5 μm by Coulter counter method) manufactured by Fuji Silysia Co., Ltd. instead of “Silo Hovic 704” of black ink A A black ink I was prepared.

(Black ink J)
The amount of black ink A “Silo Hovic 704” manufactured by Fuji Silysia Co., Ltd. was reduced from 5 parts to 11.6 parts, and black ink J was prepared in the same manner as in the black ink A production example.

(Black ink K)
Black ink A “Tospearl 2000B” is not used, and “Silicia 350D” (untreated: average particle diameter by Coulter counter method: 1.9 μm) manufactured by Fuji Silysia is used instead of “Silo Hovic 704”. In the same manner as in the black ink A production example, black ink K was prepared.

(Black ink L)
Instead of “Silo Hovic 704” manufactured by Fuji Silysia Co., Ltd., “Silicia 440” manufactured by Fuji Silysia Co., Ltd. was used, and the amount was increased from 5 parts to 0.8 part. L was created.

(Black ink M)
Using black ink A "Silo Hovic 704" manufactured by Fuji Silysia Co., Ltd. and "Silicia 440" manufactured by Fuji Sicilia Co., Inc., and increasing the amount from 5 parts to 19.8 parts. Black ink M was prepared.

(Black film A)
A polyester film K330-4.5W (thickness: 4.5 μm) manufactured by Mitsubishi Plastics Co., Ltd. is black-coated with black ink A so that the dry thickness of the ink film portion is 1.9 μm, and is aged at 40 ° C. for 2 days to be black. Ink coat film A was obtained. In addition, the thickness of the ink coating part of the colored layer was measured by cutting the cross section of the film with a razor and enlarging the cross section by 2500 times with a microscope (FIG. 3). The ink coating portion is the thickness of a layer without silica.

(Black film BJ)
Black films B to M were prepared in the same manner as the black film A except that the black inks B to M were used instead of the black ink A.

(Adhesive Preparation Example 1)
n-butyl acrylate: 97.98 parts, acrylic acid: 2 parts, 4-hydroxybutyl acrylate: 0.02 part, azobisisobutyronitrile: 0.2 part as a polymerization initiator, ethyl acetate In the solution, solution polymerization was performed at 80 ° C. for 8 hours to obtain an acrylic polymer having a weight average molecular weight of 900,000. The acrylic polymer: 100 parts, polymerized rosin ester (trade name “D-135” manufactured by Arakawa Chemical Co., Ltd.): 5 parts, and disproportionated rosin ester (trade name “KE-100” manufactured by Arakawa Chemical Co., Ltd.): 20 Part, styrene-based resin (trade name “FTR6100”: 25 parts), terpene phenol resin (trade name “YP90LL”: manufactured by Mitsui Chemicals): 1 part, ethyl acetate is added, and the pressure-sensitive adhesive has a solid content of 40%. The solution was adjusted. Further, an adhesive A was prepared by adding 0.8 parts of an isocyanate-based crosslinking agent (trade name “NC40” manufactured by DIC), and stirring and mixing so as to be uniform. The gel fraction was 20% and the storage elastic modulus at 25 ° C. was 9 × 10 ⁴ Pa.

Example 1
First, the pressure-sensitive adhesive A was applied to a release film (trade name “PET38 × 1K0”) manufactured by Nipper Co. with a roll coater so that the dry thickness was 11 μm, and dried at 100 ° C. for 1 minute. The black film A was bonded to the non-ink surface and further aged at 40 ° C. for 2 days.

(Examples 2-7 and Comparative Examples 1-3)
Instead of the black film A, Examples 2 to 10 and Comparative Examples 1 to 3 were obtained using the black films B to M as shown in Tables 1, 2, and 3.

(Evaluation)
About the adhesive tape which concerns on an Example and a comparative example, fingerprint resistance, the curl of a black film, insulation, ink adhesiveness, adhesive force, holding power, and halogen content were measured. The evaluation results are shown in Tables 1 and 2.

(Fingerprint resistance)
Press your finger against the black ink surface for a few seconds to make a fingerprint. The attached fingerprint is judged visually.
◎: No fingerprint mark is left.
○: Almost no trace of fingerprints remains.
○ △: A trace of fingerprints remains.
Δ: Some fingerprint marks remain.
×: A fingerprint mark remains.

(Black film curl)
After a black ink coated product (150 mm × 250 mm) is prepared and cured, the curl of the coated product when the coated surface is up is visually determined.
○: No curling.
X: There is curl.

(Insulation)
Measure the insulation of the black ink surface.
○: The surface resistivity is 10 ⁹ Ω / □ or more.
X: The surface resistivity is less than 10 ⁹ Ω / □.

(Black ink surface adhesion)
A Nichiban cellophane tape is pressure-bonded to the black ink coating surface, and the cellophane tape is peeled off. When peeled, the ink removal is visually determined.
(Double-circle): The ink which crimped | bonded the cellophane tape is not taken up by the cellophane tape, but all remains on the base material.
◯: Almost no ink obtained by pressure-bonding the cello tape is left on the cello tape, and 91 to 99% or more remains on the substrate.
(Triangle | delta): 50-98% of the ink which crimped | bonded the cello tape is not taken out by the cello tape, but remains in the base material.
X: 50% or more of the ink when the cello tape is pressure-bonded is taken up by the cello tape.

(Adhesive strength)
The adhesive tape is cut to a width of 25 mm and peel adhesive strength (peeling angle: 180 °, tensile speed: 300 mm / min, 23 ° C. × 50% RH, adherend) using a Tensilon tensile tester according to JIS Z0237. : Stainless steel plate, sticking time: 1 hour). The measurement results are shown in the column of “Adhesive strength (N / 25 mm)” in Table 1.

(Holding power)
The adhesive tape was cut into a width of 25 mm, a load of 100 g (25 mm × 25 mm) was applied in the vertical direction according to JIS Z0237, and the drop time was measured in an atmosphere of 100 ° C. The measurement results are shown in the “holding power” column of Table 1.

(Halogen content)
The halogen content was measured by FP method using wavelength dispersion type fluorescent X-ray “ZSX Primus” manufactured by Rigaku.
○: Less than 0.01%, ×: 0.01% or more

(Average particle size by Coulter counter method)
Measurement was performed using a Coulter Multisizer II (manufactured by Coulter Electronics Ltd .: Coulter counter method) using an aperture tube of 50 μm. The sample was dispersed by ultrasonic dispersion for 40 seconds, and an Isoton-II liquid was used as a dispersion medium. The 50% value of the weight integrated value in the particle size distribution measured by the above method was defined as the average particle size.

(Thickness of the ink coating on the colored layer)
The film was cut with a razor, the cross section of the film was observed with a microscope (digital microscope KH-7700, manufactured by HIROX), the thickness of the portion without silica was measured at 10 points, and the average value was taken as the thickness of the ink film.

(Measurement of Ra on ink surface)
For the ink surface of the colored film, in accordance with JIS-B0651 (2001), using a surface shape analyzer (manufactured by Tokyo Seimitsu Co., Ltd., Surfcom 575A), stylus tip radius 5 μm, stylus tip taper angle 90 °, measuring force 4 mN, The arithmetic average roughness (Ra) when the surface contour curve was measured under the conditions of a cutoff value of 0.8 mm, a measurement speed of 0.3 mm / s, and a reference length of 5 mm was measured.

  As apparent from Tables 1 to 3 above, the colored films of the present invention of Examples 1 to 10 had good fingerprint resistance. Moreover, when it was set as the colored adhesive tape, it had a favorable characteristic. On the other hand, the colored films of Comparative Examples 1 to 3 were inferior in fingerprint resistance.

DESCRIPTION OF SYMBOLS 1 Colored film 2 Colored layer 3 Support body 4 Adhesive layer 5 Colored layer 6 Ink film 7 Silica exposed part 8 Base material

Claims (12)

A colored pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer on at least one surface of a colored film provided with a colored layer made of a colored ink on a support, wherein the colored layer is from a colored ink containing a binder resin, a colorant and silica particles. The average particle diameter of the silica particles by Coulter counter method is 2 to 6 μm, the content of silica particles is 10 to 80 parts by mass with respect to 100 parts by mass of the binder resin in the colored ink, A colored pressure-sensitive adhesive tape , wherein a particle diameter is larger than a film thickness of an ink film of the colored layer. The colored adhesive tape according to claim 1, wherein the colorant is carbon black. The colored adhesive tape according to claim 2, wherein the carbon black is contained in an amount of 10 to 60% based on the solid content of the colored ink. The colored adhesive tape according to claim 1, wherein the silica particles are silica particles that have been subjected to hydrophobic treatment. The colored ink, colored adhesive tape according to claim 1 containing a silicone resin beads. The colored adhesive tape according to claim 1, wherein the colored layer has a surface roughness Ra of 0.35 to 1 μm . The colored adhesive tape according to claim 1, wherein the colored ink is a thermosetting ink containing a curing agent. The colored adhesive tape according to claim 1, wherein the binder resin is a urethane resin. The colored adhesive tape according to claim 8, wherein the support has a thickness of 1 μm to 4.5 μm . The colored pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive layer comprises an acrylic pressure-sensitive adhesive layer having a thickness of 1 to 50 μm. A composite comprising a magnetic sheet and a colored adhesive tape according to any one of claims 1 to 10. The heat-radiation sheet which has the structure by which the graphite sheet was protected by the colored adhesive tape of any one of Claims 1-10.