JP2007320981A - Adhesive tape and lcd module produced by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a double-faced adhesive tape having light reflecting and light shielding properties, eliminating the difference between the LCD panel side and the light source side and usable by directing either side of the adhesive tape to the LCD side or light source side. <P>SOLUTION: The adhesive tape 1 to be used by pasting between an LCD panel and a backlight case is at least composed of a substrate 40 produced by laminating a light reflection layer 20, a light shielding layer 10 and a light reflection layer 20' in the order and adhesive layers 30, 30' positioned on both faces of the substrate 40. The light transmittance measured by applying light of 10,000 cd/m<SP>2</SP>to the adhesive tape 1 is ≤1 cd/m<SP>2</SP>on both faces and the light reflectance is ≥60% on both faces. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a pressure-sensitive adhesive tape having both light reflecting properties and light shielding properties, which is used by being attached between an LCD (Liquid Crystal Display) panel and a backlight housing, and an LCD module using the same.

  LCD modules (liquid crystal display devices) are used in a wide range of fields such as word processors and personal computers. Especially, electronic notebooks, mobile phones, PHS, etc. are used as display devices for increasingly smaller electronic devices. It has become. Among such LCD modules, for example, a sidelight type backlight type LCD module 101 (schematic diagram shown in FIG. 8) generally includes a reflector 95, a light guide plate 94, A diffusion sheet 92, a prism sheet 91 (enhanced brightness) used as necessary, and an LCD panel 97 are sequentially laminated, and a light emitting diode (LED) having a lamp reflector provided on the side of the light guide plate 94, A light source 93 such as a cold cathode tube is disposed.

  Further, between the LCD panel 97 and the backlight housing 96, the LCD module adhesive tape 2 having both light reflectivity and light shielding properties (usually punched into a frame shape, the width is usually about 0.5 mm to about 10 mm). Is). The LCD module adhesive tape 2 is in contact with not only the backlight housing 96 but also the prism sheet 91 to fix the diffusion sheet 92 and the like installed on the lower side of the prism sheet 91 and to prevent dust from entering. It also has a role to prevent cracking of the above parts due to impact by providing cushioning properties.

  In the LCD module 101, the light source 93 and the LCD panel 97 become closer to each other as the lightness, thickness, and amount of information increase, and light from the light source leaks through the adhesive tape 2, so that the display surface of the LCD panel is displayed. For the purpose of dealing with inconveniences such as deterioration in appearance, the adhesive tape 2 sandwiched between the LCD panel 97 and the backlight housing 96 is required to have high light shielding properties. Further, the LCD module pressure-sensitive adhesive tape 2 has a high light reflection performance for efficiently guiding the light from the light source 93 to the back surface of the LCD panel 97 in order to cope with a thin portable device and to save power. It has been demanded. Thus, the LCD module pressure-sensitive adhesive tape 2 is strongly required to be a thin film and have light reflectivity and light shielding properties.

  Therefore, in Patent Document 1, a separator, a pressure-sensitive adhesive layer, and a base material sheet having at least two metal vapor-deposited layers are laminated in this order, and metal vapor deposition is performed on the surface opposite to the pressure-sensitive adhesive layer excluding the separator. An adhesive sheet having a structure in which no layer is exposed has been proposed. However, even if two metal deposited layers are laminated, pinholes may be generated, and it is difficult to obtain satisfactory performance in terms of light shielding properties when used as an adhesive tape for LCD modules. Moreover, since the metal vapor deposition layer is also arranged on the LCD panel side, there is a risk of electric leakage.

  Patent Document 2 and Patent Document 3 propose an adhesive tape in which a black layer and a white layer are laminated. For example, an adhesive tape for an LCD module disclosed in Patent Document 2 has a support formed by laminating a light reflecting layer and a light shielding layer, and an adhesive layer, and the light shielding layer is composed of a black ink layer, The reflective layer is composed of a white resin film. This adhesive tape has a thin film thickness, has both light reflectivity and light shielding properties, and can be used by being stuck between the LCD panel of the LCD module and the backlight housing. A black light shielding layer is disposed on the LCD panel side, and a white light reflecting layer is disposed on the light source side.

Further, Patent Document 4 discloses a method for producing a double-sided tape for a contour member, which uses the adhesive tape for an LCD module as described above to form a contour sheet for an LCD module.
JP 2002-23663 A JP 2004-156015 A JP 2004-59723 A JP 2004-26884 A

The method disclosed in Patent Document 4 is a contour formed by adhering a plurality of double-sided adhesive contour sheets having a frame shape in the length direction of a tape in a state in which a release sheet is adhered to one side surface thereof. A method for producing a double-sided tape for members,
A carrier tape having a slightly adhesive layer on one side, a first release sheet having a non-treated surface bonded to the slightly adhesive layer, a first release sheet having a release treatment, and a contour sheet forming one surface bonded to the treated surface of the first release sheet A double-sided pressure-sensitive adhesive tape, and a feed-out process of sending out a raw double-sided tape composed of a second release sheet of a single-sided treatment in which a release-treated surface is bonded to the other surface of the double-sided pressure-sensitive adhesive tape;
This is the next process of the feeding process, and it passes between the rotationally driven cutter roller / receiving roller so that the outer peripheral part of the contour sheet and the length of the original double-sided tape that connects the outer peripheral parts to each other The double-sided pressure-sensitive adhesive tape and the first double-sided pressure-sensitive adhesive tape are cut along the inner peripheral part of the contour sheet, and the first release sheet, the double-sided pressure-sensitive adhesive tape, and the second release sheet are cut along the connecting portions along the center line. Cutting process including 2 release sheets, and cutting the second release sheet along the center line in the length direction of the raw double-sided tape with a portion corresponding to the contour sheet;
Next to this cutting process, supplying the pickup tape to be attached to one side portion of the original double-sided tape separated by the center line, and winding up and removing the pickup tape after application The second release sheet corresponding to the contour sheet, the double-sided pressure-sensitive adhesive tape corresponding to the outer portion of the contour sheet, the second release sheet, and the contour sheet in one side portion of the original double-sided tape A first surplus sheet removing step of removing the second release sheet corresponding to the inclusion part;
Next to the first excess sheet removing step, the pickup tape is supplied so as to be attached to the other side portion of the original double-sided tape separated by the center line, and after the attachment, the pickup tape The second release sheet corresponding to the contour sheet, the double-sided adhesive tape corresponding to the outer portion of the contour sheet, and the second release sheet in the other side portion of the original double-sided tape And a second surplus sheet removing step of removing the double-sided pressure-sensitive adhesive tape corresponding to the inclusion portion of the contour sheet to form a contour sheet of a final shape;
It is the next process of this 2nd surplus sheet removal process, Comprising: While supplying the 3rd peeling sheet by which the single-sided peeling process was stuck to the said contour sheet, with this 3rd peeling sheet A winding process for winding the carrier tape.

  In order to process the double-sided adhesive tape for LCD modules into a frame-shaped contour sheet by such an automatable method, the peel strength balance between the layers should be properly adjusted in the original double-sided adhesive tape with the double-sided adhesive tape for LCD modules. It is necessary to adjust to.

  The double-sided pressure-sensitive adhesive tapes disclosed in Patent Document 2 and Patent Document 3 are adhered to the side where the black light-shielding layer adhered to the LCD panel (the light-shielding layer side) and the light source 93 side are adhered. In order to process the double-sided adhesive tape for LCD modules into a frame-shaped contour sheet in a manner that can be automated as described above, with the white light reflecting layer side (light reflecting layer side) being distinguished from the front and back Is designed such that one of the peel forces with the respective release sheets on both sides is larger than the other peel force.

  However, the method of processing the double-sided adhesive tape for LCD modules into a frame-shaped contour sheet is not necessarily the same depending on the processing manufacturer. Therefore, depending on the manufacturer of the double-sided tape for the contour member, it is easier to work if the peel force with the release sheet on the light shielding layer side is increased, or the peel force with the release sheet on the light reflecting layer side is greater. The demands are different. As a result, in order to supply double-sided adhesive tapes for LCD modules according to the demands of each processing manufacturer, at present, the case where the peeling force with the release layer on the light shielding layer side is increased, and the release sheet on the light reflection layer side Both of the designs are required when increasing the peeling force of the product, and the product management is complicated.

  Therefore, the problem to be solved by the present invention is a double-sided adhesive tape having both light reflectivity and light shielding property, which eliminates the distinction between the LCD panel side and the light source side, and either side of the adhesive tape is connected to the LCD. An object is to provide an adhesive tape that can be used on either the panel side or the light source side, and an LCD module using the same.

As a result of diligent research, the inventors of the present invention are adhesive tapes that are used by being stuck between an LCD panel and a backlight housing, and at least a light reflecting layer, a light shielding layer, and a light reflecting layer are laminated in this order. The support has a pressure-sensitive adhesive layer on both sides of the support, and the amount of transmitted light when the adhesive tape is irradiated with 10,000 cd / m ² of light is 1 cd / m ² or less on both sides. Thus, the present inventors have found that the above-mentioned problems can be solved by an adhesive tape characterized in that the light reflectance is 60% or more on both sides, and the present invention has been completed.
The present invention also provides an LCD module in which the above-mentioned adhesive tape is adhered between an LCD panel and a backlight housing.

  Since the pressure-sensitive adhesive tape of the present invention is excellent in both light shielding performance and light reflection performance, it is useful as a pressure-sensitive adhesive tape for fixing the LCD panel of the LCD module. Furthermore, the pressure-sensitive adhesive tape of the present invention has a support in which a light reflecting layer, a light shielding layer, and a light reflecting layer are laminated in this order, and both the light shielding performance and the light reflecting performance are excellent. When introducing into the manufacturing process, there is no need to manage the LCD panel side and the light source side separately, so it can be delivered to many processing manufacturers with various manufacturing processes as an adhesive tape with a common specification. It becomes possible.

  Below, the adhesive tape of this invention is demonstrated in more detail based on the component.

(How to use with LCD module)
The pressure-sensitive adhesive tape of the present invention can be adhered between the LCD panel and the backlight housing to form an LCD module. The adhesive tape of this invention is affixed on the position of the "adhesive tape 1" shown by FIG. At that time, one light reflecting layer 20 of the pressure-sensitive adhesive tape 1 of the present invention is adhered to the LCD panel 97 through one adhesive layer 30 so as to be in the direction of the LCD panel 97, and the other light reflecting layer 20 ′ is It sticks so that it may touch the backlight housing | casing 96 and the prism sheet 91 through the other contact bonding layer 30 'so that it may become the direction of the light source 93. FIG. FIG. 5 shows an example in which the prism sheet 91 is used. In this case, the pressure-sensitive adhesive tape 1 of the present invention is also attached to the surface of the prism sheet 91. Since the pressure-sensitive adhesive tape of the present invention is excellent in light reflectivity and light shielding properties, it can effectively reflect the light from the light source 93 toward the LCD panel 97 and prevent light from entering the driving driver 98. can do.

(Configuration of the adhesive tape of the present invention)
An embodiment of an adhesive tape of the present invention will be described with reference to the drawings.

  As shown in FIG. 1, the pressure-sensitive adhesive tape 1 of the present invention has pressure-sensitive adhesive layers 30, 30 ′ on both surfaces of a support 40 in which a light reflecting layer 20, a light shielding layer 10 and a light reflecting layer 20 ′ are laminated in this order. It is configured by stacking.

The pressure-sensitive adhesive tape of the present invention has a light transmission amount of 1 cd / m ² or less when the pressure-sensitive adhesive tape is irradiated with 10,000 cd / m ² of light. More preferably, it is 0.1 cd / m ² or less, and most preferably 0.01 cd / m ² or less. Thereby, light leakage hardly occurs and the appearance of the LCD panel is improved.

  The adhesive tape of the present invention has a light reflectance of 60% or more on both sides. More preferably, it is 65% or more. Most preferably, it is 70% or more. Thereby, the brightness | luminance of an LCD panel becomes high by guide | inducing the light from a light source to the back surface of an LCD panel efficiently. The light reflectance of the adhesive tape is generally measured when the light reflectance of the light reflecting layer 20 itself is measured and when the adhesive layer is laminated on the light reflecting layer 20. There is a case. In the case of the pressure-sensitive adhesive tape of the present invention, the light reflectance is not the light reflectance value of the light reflecting layers 20 and 20 ′ itself, but the light reflectance value including the adhesive layers 30 and 30 ′.

  The light reflectance is measured using a spectroscopic color difference meter SE-2000 type (manufactured by Nippon Denshoku Industries Co., Ltd.) in accordance with JIS Z-8722, measuring the spectral reflectance in the range of 400 to 700 nm at 10 nm intervals. It calculated as an average value (average reflectance).

  Since the pressure-sensitive adhesive tape 1 of the present invention is a double-sided pressure-sensitive adhesive tape, the LCD panel 97 can be attached to the backlight housing 96 without using parts for preventing the LCD panel 97 from being detached from the backlight housing 96. Can be fixed to.

  In the pressure-sensitive adhesive tape of the present invention, as shown in FIG. 3, at least one of the two light reflecting layers is a white ink layer or a white resin film, and constitutes the outermost layer of the support. It is preferable that the light reflectivity can be increased. FIG. 3 shows the implementation of the pressure-sensitive adhesive tape 1 of the present invention in which pressure-sensitive adhesive layers 30 and 30 ′ are laminated on both sides of a support 40 on which a white resin film 21, a light shielding layer 10 and a white ink layer 22 are laminated in this order. It is a form. The light reflecting layer can also be formed of a white resin film 21 and a white ink layer 22 as shown in FIG. It is desirable to use white ink having a white colorant content ratio higher than the white colorant content ratio in the white resin film 21. By doing so, the light reflectance in the visible light region of an adhesive tape can be made high.

  In the pressure-sensitive adhesive tape of the present invention, as shown in FIG. 2, the two light reflecting layers are both white resin films 21 and 21 ′, and constitute both outermost layers of the support. Since the white resin films 21 and 21 'having higher electrical resistance than the light reflecting layer including the metal thin film and the light shielding layer including carbon black are disposed on the LCD panel side, the light reflectance can be further increased. It is more preferable at the point which can prevent an electric leak. FIG. 2 shows the pressure-sensitive adhesive tape 1 of the present invention in which pressure-sensitive adhesive layers 30 and 30 ′ are laminated on both sides of a support 40 in which a light reflection layer 21, a light shielding layer 10 and a light reflection layer 21 ′ are laminated in this order. In the embodiment, the two light reflecting layers are both white resin films 21 and 21 '. Both the outermost layers of the support are configured, and the light shielding layer 10 can be formed of, for example, black ink. As shown in FIG. 2, the adhesive layer 12, the resin film 13, and the black ink layer 14 are formed. Are preferably laminated in this order. In the adhesive tape having this configuration, since the black ink layer 14 has a function of an adhesive layer, the adhesive layer is provided between one of the two light reflecting layers and the light shielding layer. can do. In order to make the ink layer black, a known and commonly used pigment or dye may be contained. Of these, carbon black is preferred.

  In the pressure-sensitive adhesive tape of the present invention, it is not always necessary to completely cover the top and bottom as shown in FIGS. 1 and 4, and if the light transmittance is small on both sides and the light reflectance is large on both sides, FIG. As shown in FIG. 3, the upper and lower sides may be asymmetrical.

  FIG. 4 shows the pressure-sensitive adhesive tape 1 of the present invention in which pressure-sensitive adhesive layers 30 and 30 ′ are laminated on both sides of a support 40 in which a light reflecting layer 20, a light shielding layer 10 and a light reflecting layer 20 ′ are laminated in this order. In the embodiment, the light reflecting layers 20 and 20 ′ are formed by laminating metal thin film layers 24 and 24 ′ on resin layers 23 and 23 ′. Each of the pressure-sensitive adhesive layers 30 and 30 ′ may be a single-layer pressure-sensitive adhesive layer, or may be a multilayer material composed of a plurality of pressure-sensitive adhesive layers and sheets such as a double-sided pressure-sensitive adhesive tape. good.

  The pressure-sensitive adhesive tape 1 of the present invention further includes metal thin film layers 24 and 24 ′ between the light reflecting layer 20 and the light shielding layer 10 and between the light shielding layer 10 and the light reflecting layer 20 ′. Also good. The metal thin film layers 24 and 24 ′ are not sufficiently reflected by the light reflecting layers 20 and 20 ′ and reflect the light transmitted through the layers toward the light source 93. Thereby, the light reflectivity and light shielding property of the pressure-sensitive adhesive tape 1 of the present invention are further improved.

<Light reflection layer>
(Thickness of white resin film)
For example, in the pressure-sensitive adhesive tape of the present invention shown in FIG. 2 or FIG. 3, the thickness of the white resin films 21 and 21 ′ constituting the light reflecting layer is preferably 10 to 30 μm, more preferably 12 to 25 μm. is there. If it is less than 10 μm, the workability and light reflectivity of the tape are significantly lowered. On the other hand, if it exceeds 30 μm, the thickness of the tape becomes too thick, which is not suitable for thinning the LCD module.

(Manufacture of white resin film)
The white resin films 21 and 21 ′ may be kneaded films obtained by finely dispersing a white colorant in a resin, melt-extruding the resin, and forming it into a film shape. A film in which a white ink containing a white colorant is coated on one or both sides thereof may be used. The white resin film 21 used in the present invention is preferably a white resin film in which a resin and a white colorant are kneaded and then melt-extruded to produce an unstretched film, which is biaxially stretched.

(White colorant)
Examples of the white colorant used for the white resin film 21 include barium sulfate, titanium dioxide, calcium carbonate, silica, talc, and clay. These may be used alone or in combination. In particular, considering the reflection efficiency in the wavelength region of light of 390 nm or less, titanium dioxide and barium sulfate are preferable, and titanium dioxide is most preferable among them.

  As an average particle diameter of titanium dioxide, 0.1-0.4 micrometer is preferable. When it is less than 0.1 μm, yellowishness increases in reflected light, and when it exceeds 0.4 μm, blueness increases. As addition amount of titanium dioxide, it is preferable to add in the range of 10-40 mass%, and also 15-35 mass% based on a white resin film. When the addition amount is less than 10% by mass, the average reflectance is lowered. Moreover, when it exceeds 40 mass%, it will become inferior in ductility and productivity and workability will deteriorate remarkably. When the addition amount of the white colorant is within the above range, the light reflectance of the light reflecting layer 20 can be set within the above range.

  As the light reflection layer 20 in the pressure-sensitive adhesive tape of the present invention, it is preferable to use the white resin film 21 containing the fine white colorant in the particle form as described above. By using such a white resin film 21, the light reflection layer 20 can be made a highly scattering reflection layer. As a result, the light from the light source can be reflected over a wide range without generating strong reflected light partially, and light with uniform intensity can be sent to the LCD panel side.

(Resin composition of film)
Examples of the resin of the white resin film 21 include cellophane, cellulose acetate, polyvinyl chloride, polyethylene, polypropylene, polyester, polytetrafluoroethylene, polyvinyl fluoride, polyimide, polycarbonate, polystyrene, and the like. Among these, polyester excellent in heat resistance and light resistance is preferable. Various known additives such as an antioxidant and an antistatic agent may be added to the polyester.

  Polyester is a polymer obtained by condensation polymerization of a diol and a dicarboxylic acid. Examples of the dicarboxylic acid include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, adipic acid, and sebacin. Examples of the diol include ethylene glycol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 1,6-hexanediol, diethylene glycol, neopentyl glycol, and polyoxyalkylene glycol. It is done. As the white resin film 21 used in the present invention, polyethylene terephthalate (PET) produced using terephthalic acid and ethylene glycol as raw materials is most preferable from the viewpoint of heat resistance, strength and price.

(Viscoelasticity of white resin film)
For example, the white resin film 21 used in the pressure-sensitive adhesive tape of the present invention shown in FIG. 2 or FIG. 3 has a loss in the range of 60 ° C. to 100 ° C. when viscoelasticity is measured under conditions of 0.1 Hz longitudinal stretching. It preferably has a tangent maximum. More preferably, it is the range of 70 to 95 degreeC. When the temperature is lower than 60 ° C., the heat resistance is lowered, and when the temperature exceeds 100 ° C., it is difficult to add a pigment having a high concentration. The storage modulus at 23 ° C. is preferably from the viewpoint of re-workability is ^{2.5 × 10 9 ~4.0 × 10 9} Pa. More preferably ^{3.0 × 10 9 ~3.5 × 10 9} Pa.

  The tensile strength of the white resin film 21 is preferably 10.0 N / 10 mm or more. More preferably, it is 15.0 N / 10 mm or more. Among these, 20.0 N / 10 mm or more is particularly preferable. When the tensile strength of the white resin film 21 is less than 10.0 N / 10 mm, the tape is easily broken when reworking. The higher tensile strength is preferred, but since a resin film exceeding 75.0 N / 10 mm is substantially difficult to produce, the upper limit of the tensile strength in the pressure-sensitive adhesive tape of the present invention is 75.0 N / 10 mm. is there.

  When the tensile strength of the white resin film 21 is in the above range, the adhesive tape of the present invention does not break even when the LCD panel is peeled off from the backlight housing for correcting the sticking position or the like. Remains on the housing. As described above, the white resin film 21 used in the pressure-sensitive adhesive tape of the present invention has a thin film thickness and further contains a high concentration of white colorant. However, the reworkability can be achieved by setting the tensile strength of the film within the above range. It can be set as an excellent adhesive tape. Examples of commercially available films that satisfy the above physical properties and are suitable as the white resin film 21 used in the present invention include Teflex FW2 # 13 (polyethylene terephthalate (PET) film) manufactured by Teijin DuPont Films Ltd.

(White ink layer)
For example, the white ink layer 23 can be provided as a light reflection layer like the adhesive tape of the present invention shown in FIG. In the pressure-sensitive adhesive tape of the present invention shown in FIG. 2 or FIG. 3, the white resin film 21 constituting the light reflecting layer has a white ink layer 22 on at least one surface of the white resin film in order to improve the light reflectance. Is preferably provided, and particularly preferably provided on both sides of the white resin film 21. The thickness of the white ink layer 22 is preferably 0.5 to 5 μm. The white ink layer 22 may be a single layer, but is preferably laminated in 2 to 4 layers.

  The same thing as what was used for the film can be used for the pigment of white ink. Titanium dioxide and barium sulfate are preferred, and titanium dioxide is most preferred from the viewpoint of light reflectivity. The average particle size of the white ink pigment is preferably 0.1 to 0.4 μm. The added amount of the pigment is preferably 40 to 70% by mass, more preferably 55 to 65% by mass. If the amount is less than 40% by mass, the improvement in reflectance is low, and if it exceeds 70% by mass, the ink coatability is lowered.

Examples of the ink composition include polyester resins, vinyl chloride / vinyl acetate resins, acrylic resins, nitrocellulose resins, polyurethane resins, and the like. Of these, polyester resins, polyurethane resins, and nitrocellulose resins that do not contain halogen and have excellent adhesion are preferable.
.

<Light shielding layer>
As long as the light shielding layer 10 has a function of shielding light from the light source 93 of the LCD module, the light shielding layer 10 may have a dark color other than black, for example, purple or amber, or any structure. . Below, a preferable example is described as the light shielding layer 10 in the adhesive tape 1 of this invention.

(Black ink layer)
When a black ink layer is used as the light shielding layer 10, black ink using carbon black as a pigment can be used. The thickness of the black ink layer is preferably 0.5 to 5 μm. The black ink layer may be a single layer, but is preferably laminated in 2 to 4 layers from the viewpoint of preventing pinholes.

  The ink composition is not particularly limited, and examples thereof include polyester resins, vinyl chloride / vinyl acetate resins, acrylic resins, nitrocellulose resins, and polyurethane resins. Of these, polyester resins, polyurethane resins, and nitrocellulose resins that do not contain halogen and have excellent adhesion are preferable.

  When the white ink and the black ink are overlapped and coated, it is preferable from the viewpoint of adhesion between the white ink and the black ink that the same kind of resin component is used. The same type includes, for example, polyester resin-polyester resin, vinyl chloride / vinyl acetate resin-vinyl chloride / vinyl acetate resin, acrylic resin-acrylic resin, nitrocellulose resin-nitrocellulose resin, and polyurethane resin. It refers to a resin-polyurethane resin.

(Printing method)
As the ink printing method, printing can be performed by a known and common method. For example, letterpress printing, flexographic printing, dry offset printing, gravure printing, gravure offset printing, offset printing, screen printing, and the like can be employed. Among them, the gravure printing is suitable for the repeated coating.

  The film surface to be ink-coated is preferably subjected to a known and commonly used easy adhesion treatment. Of these, easy adhesion treatment selected from corona treatment, plasma treatment, and primer treatment is preferred.

(Metal thin film layer)
For example, like the pressure-sensitive adhesive tape of the present invention shown in FIG. 4, the light reflecting layers 20 and 20 ′ can be composed of the resin layers 23 and 23 ′ and the metal thin film layers 24 and 24 ′. 24 and 24 ′ are preferably provided on the light shielding layer 10 side. Although it does not specifically limit as the metal thin film layer 24, The metal vapor deposition layer or the ink layer containing a metal is preferable. Although it does not specifically limit as a kind of metal, Aluminum or silver is preferable. Moreover, you may provide the resin layer 23 in order to improve the adhesiveness of the white resin film 21 and a metal vapor deposition layer. The resin layer 23 is particularly preferably a cellulose / polyurethane, cellulose / polyurethane, polyester, or polyester / melamine resin. Various protective layers may be provided on the metal vapor deposition layer in order to provide heat resistance and safety of the metal vapor deposition layer.

<Adhesive layer>
(Optical properties of the adhesive layer)
The pressure-sensitive adhesive layers 30 and 30 ′ used on both sides of the support of the pressure-sensitive adhesive tape of the present invention preferably have a light transmittance of 80% or more, more preferably 85% or more. The light transmittance is measured with a direct reading haze meter manufactured by Toyo Seiki Seisakusho by providing 75 μm pressure-sensitive adhesive layers 30 and 30 ′ on a polyester film “Embret S-25 μm” manufactured by Unitika.

(Anti-yellowing resistance of adhesive layer)
The pressure-sensitive adhesive layers 30 and 30 ′ used on the light reflecting layer 20 side used in the pressure-sensitive adhesive tape of the present invention are standardized by L * a * b * color system (JIS Z 8729) after being left at 100 ° C. for 14 days. L * represents lightness, and a * and b * represent chromaticity). The b * value is preferably 6 or less, more preferably 4 or less. When the b * value exceeds 6, the yellow color of the tape increases.

(Composition of adhesive layer)
As the pressure-sensitive adhesive used for the pressure-sensitive adhesive layers 30 and 30 ′, known acrylic, rubber-based, and silicon-based pressure-sensitive 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 thereof include acrylic copolymers containing repeating units derived from n-butyl acrylate, isooctyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, ethyl acrylate and the like.

  Furthermore, as a repeating unit, a repeating unit derived from an acrylic ester having a polar group such as a hydroxyl group, a carboxyl group, or an amino group in the side chain and other vinyl monomers is contained in the range of 0.01 to 15% by mass. Is preferred. 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 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 the pressure-sensitive adhesive layers 30 and 30 ′ are provided on the ink-coated surface of a white resin film having a hydroxyl value of 1 to 10 and coated with an ink containing an isocyanate-based crosslinking agent, the isocyanate-based crosslinking is performed. It is preferable to use an agent or an epoxy-based 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 less than 25%, adhesive residue tends to occur when reworking. On the other hand, if the gel fraction exceeds 80%, the adhesiveness decreases. The gel fraction is expressed as a percentage of the original mass by measuring the mass after drying of the insoluble content remaining after leaving the composition of the pressure-sensitive adhesive layers 30 and 30 'after curing in toluene and leaving it for 24 hours.

Furthermore, in order to improve the adhesive strength of the adhesive layers 30, 30 ′, a tackifying resin may be added. The tackifying resin to be added to the pressure-sensitive adhesive layers 30 and 30 ′ of the pressure-sensitive adhesive tape of the present invention is rosin resin such as rosin or rosin esterified product; terpene resin such as diterpene polymer or α-pinene-phenol copolymer A petroleum resin such as an aliphatic (C5) or aromatic (C9); a styrene resin, a phenol resin, a xylene resin, and the like. In order to reduce the b * value of the pressure-sensitive adhesive layer after standing at 100 ° C. for 14 days to 6 or less, there are few unsaturated double bonds, esterified products of hydrogenated rosin and disproportionated rosin, aliphatic and aromatic series It is preferable to add petroleum tree or the like to the adhesive layer.
In order to achieve both adhesion and yellowing resistance, it is preferable to use a highly disproportionated rosin ester, a polymerized rosin ester, and a petroleum resin in combination.

  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.

  In addition to the above, known and commonly used additives can be added to the adhesive. For example, plasticizers, softeners, fillers, pigments, flame retardants and the like can be added.

  The pressure-sensitive adhesives used for the pressure-sensitive adhesive layers 30 and 30 ′ may be different, but it is preferable to use the same pressure-sensitive adhesive for both. For example, in the method disclosed in Patent Document 4 described above, in order to process the frame by changing the release sheet and adjusting the release balance, the release force of the one adhesive layer 30 from the release sheet A, The peel strength of the other pressure-sensitive adhesive layer 30 ′ from the release sheet B is changed by changing the type of the release sheet A and the release sheet B, using the same pressure-sensitive adhesive for both. It is more preferable to make it larger than the peeling force.

  The pressure-sensitive adhesive layers 30 and 30 ′ can be formed on the base film by a method generally used for applying a pressure-sensitive adhesive sheet. The composition of the pressure-sensitive adhesive layers 30 and 30 ′ is directly applied to the base film and dried, or once applied onto a separator (release sheet), dried, and then bonded to the base film.

The thickness of the pressure-sensitive adhesive layers 30 and 30 ′ is preferably 5 to 50 μm, and more preferably 10 to 30 μm. If it is less than 5 μm, sufficient adhesion cannot be obtained. On the other hand, if it exceeds 50 μm, the thickness of the pressure-sensitive adhesive tape increases, so that it is not suitable for use in electronic devices that are becoming increasingly lighter and shorter.
When using for the said use, it is preferable that the thickness of the adhesive tape of this invention is 20-100 micrometers, and it is more preferable that it is 30-75 micrometers. Especially, it is especially preferable that it is 40-65 micrometers.

  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.

  100 parts of gravure ink “Panacia CVL-SP805 Black” manufactured by Dainippon Ink & Chemicals, Ltd., 4 parts of curing agent “CVL Hardener No. 10” manufactured by Dainippon Ink & Chemicals, Inc. Diluent “Dai Nippon Ink Chemical Co., Ltd.” Black ink B was prepared by adding 35 parts of Direducer V No.20.

  100 parts of gravure ink “Panacia CVL-SP709 White” manufactured by Dainippon Ink & Chemicals, Inc., 4 parts of curing agent “CVL Hardener No. 10” manufactured by Dainippon Ink & Chemicals, Inc. White ink W was prepared by adding 35 parts of Direducer V No.20.

[Adjustment of reflective shading film]
Apply a primer “SF primer 935” made by Dainippon Ink & Chemicals, Inc. to white polyester film “Tefflex FW2 # 13” made by Teijin DuPont Films Co., Ltd. so that the dry thickness is 1 μm, and further black to make the dry thickness 4 μm. Ink B was gravure-coated 4 times and further cured at 40 ° C. for 2 days to obtain a reflective light-shielding film a.

[adhesive]
Adhesive A was prepared by adding 10 parts of Dainippon Ink & Chemicals Co., Ltd. curing agent “KW-75” to 100 parts of adhesive “Dick Dry LX-500” manufactured by Dainippon Ink & Chemicals, Inc.

[Adjustment of reflective shading reflective film]
Adhesive A is applied to Teijin DuPont Films' white polyester film “Tefflex FW2 # 13” to a dry thickness of 1 μm, and then bonded to the reflective light-shielding film A and cured at 40 ° C. for 2 days. A reflective film A was obtained.

  The reflective light-shielding film a was gravure coated 8 times with white ink W to a dry thickness of 8 μm and cured at 40 ° C. for 2 days to obtain a reflective light-shielding reflective film B.

  Silver was vapor-deposited on both sides of a black polyester film “Diafoil B100 # 25” made by Mitsubishi Chemical Polyester Film to obtain a reflective light-shielding reflective film C.

Silver was vapor-deposited on both sides of a transparent polyester film “HPE # 25” made of Teijin DuPont Film, to obtain a reflective film D.

[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]
On an acrylic pressure-sensitive adhesive composition 1, 1.5 parts of “Coronate L-45” (isocyanate-based cross-linking agent) manufactured by Nippon Polyurethane Industry Co., Ltd. was mixed sufficiently, and then a release treatment was performed on a 75 μm thick polyester film. The film 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 surfaces of the reflective / light-shielding reflective film A, laminated with a 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.

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

(Example 3)
A double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the reflective light-shielding reflective film C was used instead of the reflective light-shielding reflective 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 reflective light shielding film a was used instead of the reflective light shielding reflective film A.

(Comparative Example 2)
A double-sided pressure-sensitive adhesive tape was obtained in the same manner as in Example 1 except that the reflective / reflective film D was used in place of the reflective / light-shielding reflective 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 Table 1.

[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 and backed 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.

[Reflectance]
Using a spectral color difference meter SE-2000 manufactured by Nippon Denshoku Industries Co., Ltd., spectral reflectance in the range of 400 to 700 nm was measured at 10 nm intervals according to JIS Z-8722, and the average value (average reflectance) Calculated as

[Evaluation of light shielding properties of tape by light box]
Adjust the light box “Flat Illuminator HF-SL-A48LCG” manufactured by Dentsu Sangyo Co., Ltd. to 10000 cd / m ² , place an adhesive tape on it, and transmit light that passes through the adhesive tape in the dark room.・ Measure with a system-made luminance meter “Eye Scale 3”.

[Tape pinhole evaluation by light box]
Adjust the light box “Flat Illuminator HF-SL-A48LCG” manufactured by Dentsu Sangyo Co., Ltd. to 10000 cd / m ² , place an A4 size adhesive tape on it, and use a pinhole that penetrates the adhesive tape in the dark room. The number was measured.
○: Less than 1 pinhole, ×: 1 pinhole or more

  As is clear from the results shown in Table 1, the pressure-sensitive adhesive tapes of the examples have high reflectivity and light shielding properties on both sides, and have few pinholes. Therefore, it is not necessary to separately manage the LCD panel side and the light source side when introducing it into the LCD module manufacturing process. Therefore, for many processing manufacturers having various manufacturing processes, an adhesive tape having a common specification is used. Can be delivered as. On the other hand, since only one surface of the adhesive tape of Comparative Example 1 is reflective, it is necessary to manage the LCD panel side and the light source side separately when introducing them into the LCD module manufacturing process. Comparative Example 2 has high reflectivity on both sides, but does not have a light-shielding layer, so has low light-shielding properties, has pinholes, and is not suitable as an adhesive tape for fixing an LCD panel of an LCD module.

BRIEF DESCRIPTION OF THE DRAWINGS It is a notional schematic sectional drawing which shows the adhesive tape 1 of this invention, Comprising: The support body 40 on which the light reflection layer 20, the light shielding layer 10, and light reflection layer 20 'were laminated | stacked, and adhesive layers 30 and 30 on this both sides 'And have. The conceptual outline which shows an example of the adhesive tape 1 of this invention which has the support body 40 on which the light reflection layer 21, the light shielding layer 10, and light reflection layer 21 'were laminated | stacked, and adhesive layer 30,30' on this both surfaces. It is sectional drawing. The two light reflecting layers are both white resin films 21 and 21 ′ and constitute both outermost layers of the support. The light shielding layer 10 includes the adhesive layer 12, the resin film 13, and the black color. The ink layer 14 is laminated. Conceptual schematic cross section showing an example of the pressure-sensitive adhesive tape 1 of the present invention having a support 40 on which a white resin film 21, a light shielding layer 10 and a white ink layer 22 are laminated, and pressure-sensitive adhesive layers 30 and 30 'on both sides thereof. FIG. The conceptual outline which shows an example of the adhesive tape 1 of this invention which has the support body 40 on which the light reflection layer 20, the light shielding layer 10, and light reflection layer 20 'were laminated | stacked, and adhesive layer 30,30' on this both surfaces. It is sectional drawing. The light reflecting layer 20 is configured by laminating a metal thin film layer 24 on a resin layer 23. 1 is a conceptual schematic cross-sectional view of an LCD module 100 in which components such as an LCD panel 97 are fixed to a backlight housing 96 using the adhesive tape 1 of the present invention. It is a conceptual schematic sectional drawing which shows an example of the conventional adhesive tape 2. FIG. It is a conceptual schematic sectional drawing which shows an example of the conventional adhesive tape 2. FIG. It is a conceptual schematic sectional drawing of the LCD module 101 which fixed each component, such as the LCD panel 97, to the backlight housing | casing 96 using the conventional adhesive tape 2. FIG.

Explanation of symbols

1: Adhesive tape 2: Adhesive tape 10: Light shielding layer 12: Adhesive layer 13: Resin film 14: Black ink layer 20, 20 ': Light reflection layer 21: Light reflection layer (white resin film)
22: Light reflecting layer (white ink layer)
23, 23 ': resin layers 24, 24': metal thin film layers 30, 30 ': adhesive layer 40: support 41: support 91: prism sheet 92: diffusion sheet 93: light source 94: light guide plate 95: reflector 96: Backlight housing 97: LCD panel 98: Driver 100: LCD module 101: LCD module

Claims (6)

It is an adhesive tape used by sticking between the LCD panel and the backlight housing,
A support body in which at least a light reflection layer, a light shielding layer and a light reflection layer are laminated in this order, and an adhesive layer on both surfaces of the support body,
Amount of light transmission when irradiated with light of the adhesive tape to 10000 cd / ^{m 2} is to both sides, and at 1 cd / ^{m 2} or less,
An adhesive tape having a light reflectance of 60% or more on both sides.   The pressure-sensitive adhesive tape according to claim 1, wherein at least one of the two light reflecting layers is a white ink layer and constitutes the outermost layer of the support.   The pressure-sensitive adhesive tape according to claim 1 or 2, wherein at least one of the two light reflecting layers is a white resin film and constitutes an outermost layer of the support.   The pressure-sensitive adhesive tape according to claim 3, wherein the two light reflecting layers are both white resin films and constitute both outermost layers of the support.   The pressure-sensitive adhesive tape according to claim 4, further comprising an adhesive layer between one of the two light reflecting layers and the light shielding layer. 6. An LCD module, wherein the adhesive tape according to claim 1 is adhered between an LCD panel and a backlight casing.

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