JP2009040901A - Light-shielding pressure-sensitive adhesive tape and lcd module using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-shielding pressure-sensitive adhesive tape having a high light-shielding effect and high insulation. <P>SOLUTION: The light-shielding pressure-sensitive adhesive tape is obtained by providing a pressure-sensitive adhesive layer to at least one surface of a substrate having a layer comprising a resin film and a carbon black-containing black ink layer. When the tape is irradiated with light of 10,000 cd/m<SP>2</SP>, the amount of transmitted light is ≤1 cd/m<SP>2</SP>, and when distilled water of 100 mL is added to the carbon black of 10 g, boiled for 10 min, is left standing, cooled to room temperature and freed of the supernatant, the remaining sludge has a pH value of ≤5. By the light-shielding pressure-sensitive adhesive tape, both of a high light-shielding effect and high insulation can be satisfied. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light-blocking pressure-sensitive adhesive tape, and more particularly to a light-blocking pressure-sensitive adhesive tape used by being attached between an LCD (Liquid Crystal Display) panel and a backlight housing.

  Display elements such as LCD modules (liquid crystal display devices) are used in a wide range of fields such as word processors and personal computers. Especially in electronic notebooks, mobile phones, PHS, etc. It has come to be used as a display device. Among such display elements, for example, a sidelight type backlight type LCD module (schematic diagram is shown in the figure) generally includes a reflector, a light guide plate, a diffusion sheet, and, if necessary, in a backlight case. Prism sheet (to increase brightness) and LCD panel are stacked in order, and a light source such as LED (Light Emitting Diode) with a lamp reflector provided on the side of the light guide plate and a cold cathode tube is arranged. Yes.

  Furthermore, an adhesive tape (usually punched into a frame shape, and the width is usually about 0.5 mm to about 10 mm) is sandwiched between the LCD panel and the backlight housing. Adhesive tape not only touches the backlight housing but also contacts the prism sheet, fixing the diffusion sheet installed under the prism sheet, and preventing impact of dust and cushioning. It also has a role to prevent cracking of the above parts.

  Furthermore, the adhesive tape is required to improve the appearance of the display surface of the LCD panel and at the same time to prevent light from entering the driver for driving the LCD panel and to prevent malfunctions. Is required.

In a conventional light-shielding pressure-sensitive adhesive tape, a black ink layer using carbon black, which is inexpensive and highly conductive, as a pigment is used as a light-shielding layer. Usually, since the black ink layer is provided between the base material and the pressure-sensitive adhesive layer, there is no conduction from the front surface and the back surface. (For example, Patent Documents 1 and 2)
However, in recent years, due to the miniaturization and thinning of portable display devices, a design in which parts are more densely packed than before has been performed, and the side of the tape and the circuit for driving the LCD are in contact with each other, causing a problem of short circuit. Therefore, a light-shielding pressure-sensitive adhesive tape having both high light-shielding properties and insulating properties is required.

Patent Document 3 uses a mixed ink composition in which an expensive cyan color material, magenta color material, and yellow color material are mixed, and the resistivity on at least one side is 10 ¹² Ω / □ or more. An adhesive tape is disclosed which is characterized. However, the above tape is very expensive, and a high light shielding property cannot be obtained unless the mixed ink is applied very thickly.

JP 2004-156015 A JP 2006-259495 A JP2007-9137

  The subject of this invention is providing the light-shielding adhesive tape which has high light-shielding property and insulation.

In the present invention, there is provided a light-shielding pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer provided on at least one surface of a base material having a layer made of a resin film and a black ink layer containing carbon black, and is 10,000 cd / m ^2. The amount of light transmission when irradiated with light of 1 cd / m ² or less, 100 ml of distilled water added to 10 g of the carbon black, boiled for 10 minutes, allowed to stand, cooled to room temperature, and the supernatant separated. It discovered that the light-shielding adhesive tape whose pH value of a thing is 5 or less has high light-shielding property and insulation, and solved the said subject.

  Since the light-shielding pressure-sensitive adhesive tape of the present invention uses a specific carbon black, both high light-shielding properties and insulation properties can be achieved. In particular, even when the total thickness is thin, it has high light-shielding properties and insulating properties, and thus can be suitably used for various display device applications, for example, miniaturized LCD module applications that require light-shielding properties.

The light-shielding pressure-sensitive adhesive tape of the present invention has a black ink layer containing carbon black on at least one surface of a base material, and has a pressure-sensitive adhesive layer on at least one surface of the base material, and 10000 cd / m ^2. The light-blocking pressure-sensitive adhesive tape has a transmission amount of 1 cd / m ² or less when irradiated with the light, and the pH of the carbon black is 5 or less. Here, the pH is the pH value of a mud obtained by adding 100 ml of distilled water to 10 g of a sample, boiling for 10 minutes, cooling to room temperature, and separating the supernatant.

[Base material]
The base material used in the present invention is obtained by providing a black ink layer on a layer made of a resin film by a known and conventional method. As a method of laminating the black ink layer on the resin film, a method of laminating by printing the ink composition can be preferably used. As a printing method, printing and lamination can be performed by a known and common method such as letterpress printing, flexographic printing, dry offset printing, gravure printing, gravure offset printing, offset printing, and screen printing. Among them, in the light shielding application, it is preferable to print and laminate on a resin film by a gravure printing method two to four times because pinholes are reduced.

  In addition, it is preferable that the resin film surface which laminates | stacks a black ink layer performs a well-known and usual easy adhesion process. Of these, easy adhesion treatment selected from corona treatment, plasma treatment, and primer treatment is preferred.

  Examples of the resin film include cellophane, polyethylene, polypropylene, nylon, polystyrene, polyimide, polyester, and the like. Among these, polyester is preferably used because it is excellent in strength and insulation. Polyethylene terephthalate is preferable because it is relatively inexpensive and excellent in heat resistance.

  The thickness of the resin film is preferably 6 to 100 μm. When the thickness is 6 μm or more, the film is hardly cracked at the time of peeling, and when it is 100 μm or less, peeling is hardly generated at the time of applying the phase. More preferably, it is 12-50 micrometers.

  Moreover, it is preferable to add various pigments, such as a white pigment and a black pigment, in a resin film, in order to provide reflectivity and light-shielding property. Various known additives such as an antioxidant and an antistatic agent may be added to the film.

[Black ink layer]
The black ink layer used in the present invention is a layer made of black ink containing carbon black as a pigment, and is a layer that imparts light shielding properties to the adhesive tape.

  In the present invention, when the pH of the carbon black in the black ink is 5 or less, the black ink layer can be provided with excellent insulating properties. It is presumed that the flow of π electrons of carbon can be suppressed by using the acidic carbon black, for example, carbon black provided with a carboxyl group or the like. The pH value is preferably 4 or less, and most preferably 3.5 or less. When the pH of the carbon black exceeds 5, the insulating property is lowered. Here, the pH is the pH value of the mud obtained by adding 100 ml of distilled water to 10 g of carbon black, boiling for 10 minutes, cooling to room temperature, and then separating the supernatant.

By using the carbon black, even when the thickness of the black ink layer is thin, excellent insulation can be exhibited. For example, even when the thickness of the black ink layer is about 5 μm, 10 ¹² Ω / The surface resistivity can be at least □, preferably at least 10 ¹³ Ω / □. The surface resistivity is measured according to JIS-K6911.

  The average primary particle diameter of carbon black is preferably 10 to 100 nm. Of these, 20 to 80 nm is most preferable. When the average primary particle diameter is within the above range, good insulating properties and dispersibility can be easily obtained.

  It is preferable to use a mixture of two or more carbon blacks having different average primary particle sizes. The inclusion of two or more types of carbon black having an average primary particle diameter of 10 to 30 nm and those having an average primary particle diameter of 30 to 100 nm is most preferable because both the light shielding property and the insulating property can be achieved at a high level.

  As content of carbon black in black ink, 20-50 mass% is preferable with respect to 100 mass% of black ink solid content. Among these, 30-40 mass% is preferable. It is easy to ensure high light-shielding properties as it is 20 mass% or more. Moreover, it is easy to maintain high insulation as it is 50 mass% or less, and the adhesiveness to a resin film also becomes favorable.

  When carbon black is dispersed in ink, it is preferably kneaded sufficiently with a bead mill or the like. By sufficiently kneading, the structure of the carbon black can be reduced, and the light shielding property and the insulating property can be improved.

  Carbon black is preferably kneaded and dispersed in advance in a small amount of polyester, polyurethane, acrylic, or the like resin before being dispersed in the ink in order to prevent the resin from being deteriorated due to the efficiency and dispersion of the manufacturing process.

  In addition to carbon black (furnace black, channel black, acetylene black, thermal black, lamp black, etc.), the black ink pigment used in the black ink layer is graphite, copper oxide, manganese dioxide, aniline black, perylene black, titanium. Black, cyanine black, activated carbon, ferrite, magnetite, chromium oxide, iron oxide, molybdenum disulfide, chromium complex, complex oxide-based black pigment, anthraquinone-based organic black pigment, and the like can be used in combination.

  The content of the pigment other than carbon black may be in a range that does not hinder the insulating properties of the carbon black used in the present invention, but the content of carbon black in all pigments is preferably 80% by mass or more, It is particularly preferably 90% by mass or more.

  Examples of the binder resin used for the black ink include polyester resins, vinyl chloride / vinyl acetate resins, acrylic resins, nitrocellulose resins, polyurethane resins, and the like. In particular, polyurethane resins, polyester resins, acrylic resins, and nitrocellulose resins are preferred as resins that meet recent halogen-free requirements.

  Of these, the combination of a polyurethane-based resin and carbon black having a pH of 5 or less is most preferable because the light-shielding property, the insulating property, and the adhesiveness with the adhesive can be highly compatible.

  The polyurethane-based resin is obtained by a polycondensation reaction of a diisocyanate compound, a polyol compound, a low molecular weight chain extender, and the like, and is a resin having high flexibility and elasticity having many urethane bonds in the molecule. As a polyurethane-type resin used for this invention, the thing of mass average molecular weight 1,000-500,000 is preferable, More preferably, it is 30,000-100,000.

  Specific examples of the diisocyanate compound suitably used in the present invention 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; Dials such as 4,4′-diphenyldimethylmethane diisocyanate Dialkylmethane diisocyanate, tetraalkyldiphenylmethane diisocyanate such as 4,4'-diphenyltetramethylmethane diisocyanate, 1,5-naphthylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyldimethylmethane diisocyanate, 4,4 Examples include aromatic diisocyanates such as' -dibenzyl isocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and m-tetramethylxylylene diisocyanate; amino acid diisocyanates such as lysine diisocyanate. It is done. These polyisocyanate compounds including these diisocyanate compounds are used alone or in admixture of two or more.

  Examples of the polyol compound suitably used in the present invention include polyether polyols, polyester polyols, polycarbonate polyols, polybutadiene polyols, and the like. Examples of the polyether polyols include polyethylene glycol obtained by ring-opening polymerization of ethylene oxide, propylene oxide, tetrahydrofuran and the like, polypropylene glycol, polyoxytetramethylene ether glycol and the like. Examples of polyester polyols include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, pentanediol, Saturated or unsaturated low molecular weight glycols such as 3-methyl-1,5-pentanediol, 1,6-hexanediol, octanediol, 1,4-butynediol, dipropylene glycol, bisphenol A and hydrogenated bisphenol A And dibasic acids such as adipic acid, maleic acid, fumaric acid, phthalic anhydride, isophthalic acid, terephthalic acid, succinic acid, oxalic acid, malonic acid, glutaric acid, pimelic acid, azelaic acid, sebacic acid, suberic acid, etc. Acid anhydrides corresponding to Water condensation compound obtained, and the like.

  In addition, it is preferable to add a cellulose-based resin having high dispersibility as a dispersant because high light-shielding properties can be obtained. Examples of the cellulose resin include nitrified cotton and cellulose acetate propionate. The addition amount of the resin is preferably 0.05 to 10% by mass with respect to the solid content of the ink. More preferably, it is 0.1-3 mass%.

  By containing a blocking inhibitor in the black ink, the generation of pinholes due to blocking can be suppressed. Antiblocking agents such as silica, calcium carbonate, calcium phosphate, talc, etc., and organic compound antiblocking agents such as polyethylene wax (PE wax), fatty acid amide, fatty acid ester, higher fatty acid should be used. Is preferred. The particle-based anti-blocking agent prevents the blocking by forming irregularities on the surface of the ink layer and reducing the contact area between the ink surface and the back surface. On the other hand, the organic compound-based antiblocking agent prevents blocking by bleeding out on the surface of the ink layer. Therefore, it is preferable to use a particle-based anti-blocking agent and an organic compound-based anti-blocking agent in combination. In particular, silica that improves the adhesion to the pressure-sensitive adhesive is preferred as the particle-based antiblocking agent. Further, as the organic compound-based anti-blocking agent, PE wax that does not significantly reduce the adhesion with the pressure-sensitive adhesive is particularly preferable.

  The addition amount of the particle size blocking inhibitor is preferably 1 to 10% by mass with respect to the ink solid content. Among these, 2-7 mass% is more preferable. If it is 1% by mass or more, the effect of preventing blocking is suitably exhibited, and if it is 10% by mass or less, the ink film is unlikely to become brittle. On the other hand, the addition amount of the organic blocking inhibitor is preferably 1 to 10% by mass with respect to the ink solid content. Among these, 2-7 mass% is more preferable. If it is 1 mass% or more, the effect of blocking prevention will be acquired suitably, and adhesiveness with an adhesive will become favorable in it being 10 mass% or less. Moreover, you may contain other various additives as needed.

  The thickness of the black ink layer is preferably 2 to 20 μm. Among these, 4-6 micrometers is more preferable. When the thickness is 2 μm or more, the light shielding property is hardly reduced. When the thickness is 20 μm or less, the curling of the substrate due to the curing shrinkage of the ink hardly occurs, the workability of the tape becomes good, and it is suitable as an LCD module tape that is required to be thin.

[Light reflection layer]
In the light-shielding pressure-sensitive adhesive tape of the present invention, the surface opposite to the black ink layer has light reflectivity, whereby a light reflection effect can be obtained and the luminance of the display device can be improved. Such a light reflection layer is not particularly limited, but the reflectance is preferably 60% or more, more preferably 80% or more, and most preferably 90% or more.

  As the reflective layer, a light-reflective layer such as a white ink may be formed in a resin film shape, or a commercially available thin film having light reflectivity may be laminated on the resin film. . Moreover, the layer which consists of a resin film, and a light reflection layer can also be made into the same layer by using a white resin film as a resin film.

  As commercially available light-reflective resin films, 3M ESR, Toray E # 38, Mitsubishi Chemical Polyester Film W400 # 38, Teijin DuPont Teflex FW2 # 13, etc. are excellent in insulation and thin. It is preferable because of its high reflectivity. A metal-deposited film such as Reiko 37W01 cannot be used because it has a conductive layer.

[Adhesive layer]
As the pressure-sensitive adhesive layer used in the present invention, those having good adhesiveness with a resin film or a black ink layer can be used, and known acrylic, rubber-based, or silicon-based pressure-sensitive adhesive resins can be used. Among them, an acrylic copolymer containing a repeating unit derived from an acrylate ester having an alkyl group having 2 to 14 carbon atoms as a repeating unit is preferable from the viewpoint of light resistance and heat resistance.

  Examples of the acrylic copolymer include acrylic copolymers containing repeating units derived from n-butyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, ethyl acrylate, and the like. Among these, the halogen or sulfur content is preferably less than 0.3% by mass, more preferably less than 0.1% by mass, particularly preferably substantially free of halogen or sulfur. Among them, those containing 50% by mass or more of n-butyl acrylate have excellent adhesion to an ink layer using a polyurethane resin, and more preferably those containing 90% by mass or more have excellent adhesion.

  Further, as a repeating unit, a repeating unit derived from an acrylate ester having a polar group such as a hydroxyl group, a carboxyl group or an amino group in the side chain or other vinyl monomer is contained in a range of 0.01 to 15% by mass. Is preferred. Moreover, it is excellent in adhesiveness with the ink layer which uses a polyurethane-type resin to contain an acrylic acid unit in 2-10 mass%, and preferable.

  The acrylic copolymer can be obtained by copolymerization by a solution polymerization method, a bulk polymerization method, a suspension polymerization method, an emulsion polymerization method, an ultraviolet irradiation method, or an electron beam irradiation method. The average mass molecular weight of the acrylic copolymer is preferably 400,000 to 1,400,000, and more preferably 600,000 to 1,200,000.

  Furthermore, it is preferable to add a crosslinking agent in order to increase the cohesive strength of the pressure-sensitive adhesive. Examples of the crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, and a chelate crosslinking agent. In particular, when an adhesive layer is provided, it is preferable to use an isocyanate crosslinking agent or an epoxy crosslinking agent. The addition amount of the crosslinking agent is preferably adjusted so that the gel fraction of the pressure-sensitive adhesive layer is 25 to 80%. A more preferable gel fraction is 30 to 70%. Among these, 35 to 60% is most preferable. When the gel fraction is 25% or more, adhesive residue hardly occurs when reworking. On the other hand, if the gel fraction is less than 80%, the adhesive strength is good. Adhesiveness decreases. The gel fraction is expressed as a percentage of the original mass by immersing the composition of the pressure-sensitive adhesive layer after curing in toluene, measuring the mass after drying of the insoluble matter remaining after standing for 24 hours, and measuring the mass.

  Furthermore, in order to improve the adhesive strength of the pressure-sensitive adhesive layer, a tackifier resin may be added. The tackifier resin to be added to the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present invention is a rosin resin such as rosin or an esterified product of rosin; a terpene resin such as a diterpene polymer or α-pinene-phenol copolymer; an aliphatic resin. Petroleum resins such as (C5) and aromatic (C9); styrenic resins, phenolic resins, xylene resins and the like. An acrylic resin other than the acrylic copolymer may be added as a tackifying resin.

  As addition amount of tackifying resin, when an adhesive resin is an acrylic copolymer, it is preferable to add 10-60 mass parts with respect to 100 mass parts of acrylic copolymers. When attaching importance to adhesiveness, it is most preferable to add 20 to 50 parts by mass. When the adhesive resin is a rubber-based resin, it is preferable to add 80 to 150 parts by mass of the tackifier resin to 100 parts by mass of the rubber-based resin. In general, when the adhesive resin is a silicon resin, no tackifying resin is added.

  Moreover, black colorants, such as carbon black, and other well-known usual additives can be added as needed. Examples of other additives include plasticizers, softeners, fillers, pigments, flame retardants, and the like.

  As for the thickness of an adhesive layer, 5-50 micrometers is preferable, More preferably, it is 10-30 micrometers. If it is 5 μm or more, sufficient adhesiveness can be obtained, and if it is 50 μm or less, it can be suitably applied to a display device or the like that is becoming lighter and thinner.

An adhesive layer can be formed on a resin film or a black ink layer by the method generally used for application | coating of an adhesive sheet. Specifically, for example, the composition for forming the pressure-sensitive adhesive layer is directly applied to a resin film or black ink layer and dried, or once applied on a separator and dried, the resin film or black ink layer is then applied. It can be formed by a method of bonding.
[Light-shielding adhesive tape]
The light-shielding pressure-sensitive adhesive tape of the present invention can achieve both high light-shielding properties and high insulating properties by using the base material having the black ink layer and the pressure-sensitive adhesive layer.

  As an embodiment of the light-shielding pressure-sensitive adhesive tape of the present invention, any structure may be used as long as a pressure-sensitive adhesive layer is provided on at least one surface of a substrate having a layer made of a resin film and a black ink layer. Specifically, an embodiment having a black ink layer and a pressure-sensitive adhesive layer only on one side of the layer made of a resin film, a side having a black ink layer and a pressure-sensitive adhesive layer on one side of the layer made of a resin film, and the other side The form etc. which have an adhesive layer in can be illustrated. Moreover, embodiment which has a black ink layer and an adhesive layer on both surfaces of the layer which consists of a resin film may be sufficient. Furthermore, the embodiment which provided the adhesive layer on both surfaces of the base material which laminated | stacked the reflection layer and the black ink layer on the single side | surface of the layer which consists of a light-reflective resin film may be sufficient. What is necessary is just to select these aspects suitably by a use application.

  The pressure-sensitive adhesive layer may be a single-layer pressure-sensitive adhesive layer, or may be a multilayer composed of a plurality of pressure-sensitive adhesive layers and sheets such as a double-sided pressure-sensitive adhesive tape.

  For the lamination of the black ink layer on the layer made of the resin film, a method of laminating by printing the ink composition can be preferably used. As a printing method, printing and lamination can be performed by a known and common method such as letterpress printing, flexographic printing, dry offset printing, gravure printing, gravure offset printing, offset printing, and screen printing. Among them, in the light shielding application, it is preferable to print and laminate on a resin film by a gravure printing method two to four times because pinholes are reduced.

  In addition, it is preferable that the resin film surface which laminates | stacks a black ink layer performs a well-known and usual easy adhesion process. Of these, easy adhesion treatment selected from corona treatment, plasma treatment, and primer treatment is preferred.

  The pressure-sensitive adhesive layer can be formed on a layer made of a resin film or a black ink layer by a method generally used for coating a pressure-sensitive adhesive sheet. Specifically, for example, the composition for forming the pressure-sensitive adhesive layer is directly applied to a resin film or black ink layer and dried, or once applied on a separator and dried, the resin film or black ink layer is then applied. It can be formed by a method of bonding.

  The thickness of the light-shielding pressure-sensitive adhesive tape of the present invention is preferably 20 to 100 μm, and more preferably 30 to 75 μm. Especially, it is especially preferable that it is 40-65 micrometers. Those having a thickness in this range can be suitably used for a display device, particularly for an LCD module.

The light-shielding pressure-sensitive adhesive tape of the present invention has a light transmission amount of 1 cd / m ² or less when irradiated with light of 10,000 cd / m ² in order to suppress malfunction due to light incidence. More preferably, it is 0.1 cd / m ² or less. For example, as a light box of 10,000 cd / m ^2, a flat illuminator HF-SL-A48LCG manufactured by Dentsu Sangyo Co., Ltd. can be used, for example. As the luminance meter, for example, Eye System 3 eye scale 3, Eye scale 4 and Topcon Techno House BM-5A, BM-7, BM-9, etc. can be used.

[LCD module]
The light-shielding pressure-sensitive adhesive tape of the present invention is highly suitable for various display devices because it is highly compatible with light-shielding properties and insulation, and is particularly suitable as a light-shielding pressure-sensitive adhesive tape for thin LCD modules with reduced space. Can be used for

  In addition, the light-shielding pressure-sensitive adhesive tape of the present invention can realize excellent light-shielding properties and adhesiveness, and is therefore suitable for sticking between the LCD panel and the backlight housing of the LCD module having the LCD panel and the backlight housing. It is. Examples of such an LCD module include a sidelight type backlight type LCD module.

  The LCD module using the light-shielding pressure-sensitive adhesive tape of the present invention has high reliability because the cause of malfunction due to short-circuiting or light leakage is reduced even when the parts are densely designed. An LCD module in which the light-shielding pressure-sensitive adhesive tape of the present invention having a light reflecting layer is attached so that the black ink layer side faces the LCD panel side and the light reflecting layer side faces the backlight housing side can achieve excellent luminance.

  As shown in FIG. 1, the general configuration of the sidelight type backlight system includes a reflector 4, a light guide plate 3, a diffusion sheet 2, and a prism used as necessary, in a backlight housing 7. A sheet (increasing brightness) and an LCD panel 6 are laminated in order, and a light reflector 4 having a lamp reflector provided on the side of the light guide plate, a light source 4 such as an LED (Light Emitting Diode), a cold cathode tube, etc. is arranged. . The light-shielding pressure-sensitive adhesive tape 1 of the present invention can be exemplified by a preferred embodiment in which the frame is punched and sandwiched between the LCD panel 6 and the backlight housing 7.

  Since the light-shielding pressure-sensitive adhesive sheet of the present invention can suppress malfunction of peripheral devices and provides a highly reliable product, it is suitably used for display devices of miniaturized electronic devices such as electronic notebooks, mobile phones, and PHS. The LCD module which can be used and contains this light-shielding adhesive sheet can be used suitably for these electronic device uses.

  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.

[Create black ink]

Carbon black 1: Special black 4 from Degussa
(PH = 3, average primary particle size = 25 nm, oil absorption = 280)
Carbon Black 2: Degussa Special Black 250
(PH = 3, average primary particle size = 56 nm)
Polyurethane: KL-564 manufactured by Arakawa Chemical Co., Ltd.
Silica: Silicia 350D manufactured by Fuji Silysia Chemical Ltd.
PE wax: Mitsui Chemicals high wax 220MP
MEK: Methyl ethyl ketone

  To 100 parts of black ink ab, 8 parts of a curing agent “XS100 Hardener No. 100” manufactured by Dainippon Ink & Chemicals, Inc. and 35 parts of a diluent “Dai Reducer V No. 20” manufactured by Dainippon Ink & Chemicals, Inc. are added. Thus, black inks A to B were prepared.

  Similarly, 100 parts of “Panacia CVL-SP805 ink” manufactured by Dainippon Ink and Chemicals, Inc., and 4 parts of “CVL Hardener No. 10” manufactured by Dainippon Ink and Chemicals, Dai Nippon Ink Chemical Co., Ltd. A black ink C was prepared by adding 35 parts of “Direducer V No. 20” manufactured by Kogyo Co., Ltd. The carbon black of Panacea CVL-SP805 black has a pH = 7 and an average primary particle size = 28 nm.

[Adjustment of support]
A white PET film “Teflex # 13” manufactured by Teijin DuPont Films Ltd. was corona treated to 50 mN / m, and black ink a was gravure coated 3 times so that the dry thickness was 4 μm. Further, the film was cured at 40 ° C. for 2 days to obtain a light shielding film A. At this time, the surface resistivity of the black ink of the light shielding film A was 5 × 10 ¹² Ω / □.

A white PET film “Teflex # 13” manufactured by Teijin DuPont Films Ltd. was corona-treated to 50 mN / m, and black ink b was gravure coated three times so that the dry thickness was 4 μm. Further, the film was cured at 40 ° C. for 2 days to obtain a light-shielding film B. At this time, the surface resistivity of the black ink of the light shielding film B was 10 ¹³ Ω / □.

Terajin DuPont Films Co., Ltd. white PET film “Teflex # 13” is corona treated to 50 mN / m, and black ink C (Panacia CVL-SP805 black) is gravure coated 3 times to a dry thickness of 4 μm did. Further, the film was cured at 40 ° C. for 2 days to obtain a light-shielding film C. The surface resistivity of the black ink of the light shielding film C was 2 × 10 ⁵ Ω / □.

Teijin DuPont Films Co., Ltd. white PET film “Teflex # 13” was corona treated to 50 mN / m, and a mixed ink composition containing a cyan color material, a magenta color material and a yellow color material was obtained. Gravure coating was performed 4 times so that the dry thickness was 7 μm. Further, the film was cured at 40 ° C. for 2 days to obtain a light-shielding film D. The surface resistivity of the black ink of the light shielding film D was 5 × 10 ¹² Ω / □.

[Adjustment of adhesive]
(Preparation 1 of acrylic copolymer)
In a reaction vessel equipped with a condenser, a stirrer, a thermometer, and a dropping funnel, 92.8 parts of n-butyl acrylate, 5 parts of vinyl acetate, 2 parts of acrylic acid, 0.2 part of β-hydroxy-ethyl acrylate, and a polymerization initiator As follows, 0.2 part of 2,2′-azobisisobutylnitrile is dissolved in 100 parts of ethyl acetate, and after substitution with nitrogen, polymerization is carried out at 80 ° C. for 8 hours to obtain an acrylic copolymer 1 having a mass average molecular weight of 800,000. It was.

(Preparation of acrylic pressure-sensitive adhesive composition 1)
100 parts of the above acrylic copolymer 1, 20 parts of disproportionated rosin ester “Superester A100” manufactured by Arakawa Chemical Co., Ltd., and 20 parts of tackifier resin “FTR6100” manufactured by Mitsui Petrochemical Co., Ltd. The pressure-sensitive adhesive composition 1 having a solid content of 40% by mass was obtained.

Example 1
[Production of adhesive tape]
1.5 parts of an isocyanate-based crosslinking agent “Coronate L-45” manufactured by Nippon Polyurethane Industry Co., Ltd. was blended into the acrylic pressure-sensitive adhesive composition 1, and after sufficiently stirring, on a polyester film having a thickness of 75 μm subjected to a release treatment, It was coated so that the thickness after drying was 18 μm, and dried at 100 ° C. for 2 minutes to obtain an adhesive layer. This was transferred onto both sides of the light-shielding film (A), laminated with an 80 ° C. hot roll at a pressure of 4 kgf / cm, and further cured at 40 ° C. for 2 days to obtain a double-sided adhesive tape. The gel fraction of the pressure-sensitive adhesive layer was 40%.

(Example 2)
A double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the light-shielding film (B) was used instead of the light-shielding film (A).

(Comparative Example 1)
A double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the light shielding film (C) was used instead of the light shielding film (A).

(Comparative example 2) The double-sided adhesive tape was obtained like Example 1 except having used the light shielding film (D) instead of the light shielding film (A).

  About the double-sided adhesive tape obtained in the said Example and comparative example, the following items were evaluated. The obtained results are shown in Tables 2-3.

[Adhesive strength]
The adhesive strength was determined by the following procedure in accordance with the JIS-Z0237 (2000) 180-degree peeling adhesive strength test method.
The pressure-sensitive adhesive tapes of Examples and Comparative Examples 20 mm wide lined with a polyester film 25 μm on a stainless steel plate were pressure-applied once with a 2 kg roller under the conditions of an environmental temperature of 23 ° C. and a humidity of 50%, and left for 1 hour. Using a Tensilon universal tensile tester (Orientec, RTA100), the film was pulled at a speed of 300 mm / min under the same temperature and humidity conditions, and then peeled off by 180 degrees to measure the adhesive force.

[Light shielding]
The light box “Flat Illuminator HF-SL-A48LCG” manufactured by Dentsu Sangyo Co., Ltd. is adjusted to 10000 cd / m ² , and a light-shielding adhesive tape is placed on the light box. ) Measure with an eye system luminance meter “eye scale 3”.
A permeation amount of 1 cd / m ² or less was determined to be good.

[Surface resistivity]
The surface resistivity was measured at a voltage of 500 V according to JIS K6911 using a resistivity meter TR-42 and R8340A manufactured by Advantest Corporation.
Those having a surface resistivity of 10 ¹² Ω / □ or more were judged good.

  As is clear from the results shown in Tables 2 and 3, the pressure-sensitive adhesive tapes of the examples are excellent in light-shielding properties and insulation properties because they use carbon black having a pH of 5 or lower.

  On the other hand, since the adhesive tape of Comparative Example 1 has a low surface resistivity of the black ink layer, it is inferior in insulation. The pressure-sensitive adhesive tape of Comparative Example 2 has a high surface resistivity but is inferior in light shielding properties.

It is a schematic sectional drawing of the LCD module which fixed the LCD panel to the backlight housing | casing using the adhesive tape of this invention.

Explanation of symbols

1: Adhesive tape 2: Diffusion sheet 3: Light guide plate 4: Reflector plate 5: Light source 6: LCD panel 7: Backlight housing

Claims (9)

A light-shielding pressure-sensitive adhesive tape in which a pressure-sensitive adhesive layer is provided on at least one surface of a substrate having a layer made of a resin film and a black ink layer containing carbon black,
Light transmission amount of when irradiated with light of 10000 cd / ^{m 2} is a 1 cd / ^{m 2} or less,
100 ml of distilled water is added to 10 g of the carbon black, boiled for 10 minutes, allowed to stand, cooled to room temperature, and the pH value of the muddy material from which the supernatant is separated is 5 or less. . 2. The light-shielding pressure-sensitive adhesive tape according to claim 1, wherein the black ink layer has a thickness of 2 to 20 μm and the black ink layer has a surface resistivity of 10 ¹² Ω / □ or more. The light-shielding pressure-sensitive adhesive tape according to claim 1 or 2, wherein the content of the carbon black is 20 to 50% with respect to 100% of the black ink solid content. The light-shielding pressure-sensitive adhesive tape according to claim 1, wherein the black ink contains a polyurethane-based resin as a binder resin. The light-shielding pressure-sensitive adhesive tape according to any one of claims 1 to 4, comprising carbon black having an average primary particle diameter of 10 to 100 nm. The light shielding property according to any one of claims 1 to 5, wherein the carbon black is a carbon black obtained by mixing carbon black having an average primary particle size of 30 nm to 100 nm and carbon black having an average primary particle system of 10 nm to 30 nm. Adhesive tape. The light-shielding pressure-sensitive adhesive tape according to any one of claims 1 to 6, wherein the pressure-sensitive adhesive layer contains an acrylic copolymer containing 2 to 10% by mass of an acrylic acid unit. The light-shielding pressure-sensitive adhesive tape according to claim 1, having a total thickness of 100 μm or less. An LCD module having an LCD panel and a backlight housing, wherein the LCD panel and the backlight housing are adhered with the light-shielding adhesive tape according to claim 1. A featured LCD module.

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