JP2008274243A - Adhesive tape and lcd module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an adhesive tape having excellent repulsion resistance under wide range temperature circumstance from a low temperature to a high temperature. <P>SOLUTION: The adhesive tape has an adhesive layer on at least one side of a substrate, in which the adhesive layer comprises an acryl copolymer and a tackifying resin. The acryl copolymer comprises 0.1-3% by mass of a nitrogen-containing vinyl monomer as a monomer component and a polymerized rosin ester-based resin and a terpene phenol-based resin as the tackifying resin. The adhesive tape has a peak temperature of loss tangent of -15 to 5°C in a loss tangent curve of a dynamic viscoelasticity spectrum measured at a frequency of 1 Hz of the adhesive layer. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a pressure-sensitive adhesive tape having suitable repulsion resistance under both high temperature and low temperature environments, and an LCD module using the pressure-sensitive adhesive tape.

  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. As an example of such an LCD module, there is a sidelight type backlight type LCD module. In such an LCD module, an adhesive tape (usually punched in a frame shape) is provided between the LCD panel and the backlight housing. The width of the LCD panel is usually about 0.5 mm to about 10 mm), and the LCD panel is fastened to the backlight housing with the FPC folded. (See Patent Document 1). Such an adhesive tape is required to have a suitable repulsion resistance that does not peel off in an environment of low temperature or high temperature and high humidity against the repulsive force of the FPC for a long period of time, or does not cause the LCD panel to come out.

  As a pressure-sensitive adhesive tape having excellent resilience resistance, a double-sided pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having a maximum loss tangent (tan δ) in a temperature range of −40 to −15 ° C. is disclosed (see Patent Document 1). The double-sided pressure-sensitive adhesive tape has excellent adhesive strength that does not peel even when repulsive force occurs over time under normal use environment. However, due to the further thinning of LCD modules in recent years, the pressure-sensitive adhesive tape has become thinner. For this reason, when the adhesive tape is used at a high temperature, the LCD panel fixed with the double-sided adhesive tape may float from the backlight housing, and there is a problem that the visibility of the image display unit deteriorates. .

  In addition, the pressure-sensitive adhesive tape having strong adhesive force and good resilience includes, for example, an acrylic copolymer containing a high-polar vinyl monomer as a monomer component, and the maximum value of loss tangent is 5 ° C. or less. An adhesive tape using a strong adhesive re-peelable adhesive is disclosed (see Patent Document 2). Since the adhesive of the adhesive tape has a highly polar vinyl monomer, it has excellent adhesion to the object to be deposited, but when the adhesive tape is used in a low temperature environment, it may cause peeling due to repulsive force. When the thickness of the pressure-sensitive adhesive layer is as thin as about 10 μm, there is a problem that peeling occurs more remarkably.

JP 2006-10931 A JP 2000-239632 A

  The problem to be solved by the present invention is to provide a pressure-sensitive adhesive tape excellent in resilience resistance under a wide temperature environment from low temperature to high temperature.

  In the present invention, the acrylic copolymer containing a nitrogen-containing vinyl monomer having suitable adhesion to the adherend as a monomer component contains different types of tackifying resin of polymerized rosin ester resin and terpene phenol resin. By setting the loss tangent peak within a low temperature range, it is possible to realize a pressure-sensitive adhesive tape having suitable repulsion resistance over a wide temperature range.

  That is, the present invention is an adhesive tape having an adhesive layer on at least one surface of a substrate, wherein the adhesive layer contains an acrylic copolymer and a tackifying resin, and the acrylic copolymer is used as a monomer component. 0.1 to 3% by mass of a nitrogen-containing vinyl monomer, a polymerized rosin ester-based resin and a terpenephenol-based resin as the tackifying resin, and a dynamic viscoelastic spectrum at a frequency of 1 Hz of the pressure-sensitive adhesive layer The temperature which shows the peak of the loss tangent in the loss tangent curve of -15 degreeC-5 degreeC is an adhesive tape.

The pressure-sensitive adhesive tape of the present invention is excellent in repulsion resistance not only in the use environment at normal temperature but also in low temperature or high temperature, so that the pressure-sensitive adhesive tape is peeled even when repulsive force occurs over time in a harsh environment Does not occur. For this reason, the LCD module using the pressure-sensitive adhesive tape of the present invention can display images favorably without causing defects in the image display portion and deterioration of visibility due to peeling of the pressure-sensitive adhesive tape.
Further, the pressure-sensitive adhesive tape of the present invention can be suitably used for a thin LCD module because it exhibits excellent repulsion resistance even when the thickness of the pressure-sensitive adhesive layer is about 5 μm on one side.

[Adhesive]
(Acrylic copolymer)
The acrylic copolymer used for the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present invention contains a nitrogen-containing vinyl monomer as a monomer component, and the content of the nitrogen-containing vinyl monomer constitutes the acrylic copolymer. It is 0.1-3 mass% in a monomer component, Preferably it is 0.5-2 mass%. Thereby, when the adhesive layer of an adhesive tape is formed, the cohesive force of an adhesive layer becomes favorable, and when the repulsive force is added to an adhesive tape, it becomes difficult to produce the cohesive failure of an adhesive.

(Nitrogen-containing monomer)
Examples of the nitrogen-containing vinyl monomer include N-vinylpyrrolidone, N-vinylcaprolactam, acryloylmorpholine, N, N-dimethylacrylamide, dimethylaminoacrylate and the like. Of these, N-vinylpyrrolidone is preferred.

(Alkyl acrylate monomer)
As another monomer component which comprises an acrylic copolymer, what is generally used for an adhesive use can be used, Especially, the (meth) acrylic acid ester which has a C1-C14 alkyl group is preferable. Examples of the (meth) acrylic acid ester having an alkyl group having 1 to 14 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl. (Meth) acrylate, isobutyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n -Nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, n-lauryl (meth) acrylate etc. are mentioned, It can use individually or in combination of 2 or more types. Of these, n-butyl acrylate is preferred as the main component. The amount of the (meth) acrylic acid ester having an alkyl group having 1 to 14 carbon atoms is preferably 70% by mass or more in the monomer component constituting the acrylic copolymer, and more preferably 90% by mass or more. preferable.
In addition, in order to increase the cohesive strength of the acrylic copolymer as required, carboxyl group-containing vinyl monomers such as vinyl acetate and the like, (meth) acrylic acid, itaconic acid, maleic acid, and (meth) acrylic acid dimer are added. It may be copolymerized.

(Vinyl monomer having a functional group)
It is also preferable to use a vinyl monomer having a functional group that reacts with the crosslinking agent in order to increase the cohesive force of the pressure-sensitive adhesive layer by suitably crosslinking with the crosslinking agent. The vinyl monomer having a functional group that reacts with the crosslinking agent is not particularly limited, but includes a hydroxyl group-containing vinyl monomer such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 4-hydroxybutyl acrylate, an amine-containing vinyl monomer, and the like. Is mentioned. Of these, 4-hydroxybutyl acrylate is preferable. It is preferable that the usage-amount of the vinyl monomer which has a functional group is 0.01 mass%-1.0 mass% in the monomer component which comprises an acrylic copolymer, and it is 0.03-0.5 mass%. Is particularly preferred.

(Molecular weight of acrylic copolymer)
The weight average molecular weight in terms of standard polystyrene as measured by gel permeation chromatography (GPC) of the acrylic copolymer is preferably 400,000 to 1,400,000, more preferably 600,000 to 900,000.

(Tackifying resin)
In the present invention, as a tackifier resin, a polymerized rosin ester-based resin having a softening point of 80 ° C to 150 ° C, preferably 110 ° C to 140 ° C, and a softening point of 100 ° C to 150 ° C, preferably 120 ° C to 140 ° C. Together with the terpene phenolic resin. As a result, the pressure-sensitive adhesive layer used in the present invention can realize suitable adhesion to an object to be adhered in a wide temperature range from low temperature to high temperature, and can provide a pressure-sensitive adhesive tape having excellent resilience resistance.

(Quantity ratio)
Content of the said terpene phenol-type resin in the adhesive which forms the adhesive layer of the adhesive tape of this invention is 0.1-0.3 by mass ratio with respect to the said acrylic copolymer. Preferably it is 0.15-0.25. Moreover, as for the adhesive used for this invention, content of the said polymerization rosin ester-type resin is 0.1-1.5 by mass ratio with respect to a terpene phenol-type resin. Preferably it is 0.3-1.0.

(Description of crosslinking agent)
As a crosslinking agent mix | blended with an adhesive in order to form the adhesive layer of the adhesive tape of this invention, an isocyanate type crosslinking agent, an epoxy-type crosslinking agent, and a chelate type crosslinking agent are mentioned, for example. Of these, isocyanate-based crosslinking agents are preferred.

[Adhesive tape]
The pressure-sensitive adhesive tape of the present invention has a pressure-sensitive adhesive layer made of the above-mentioned pressure-sensitive adhesive on at least one surface of a base material, and a single-sided pressure-sensitive adhesive tape provided with a pressure-sensitive adhesive layer on one surface of the base material, or a pressure-sensitive adhesive layer on both surfaces of the base material. It is formed in the form of a provided double-sided pressure-sensitive adhesive tape, and a release sheet is provided on the pressure-sensitive adhesive layer as necessary. In any case, the pressure-sensitive adhesive layer to be laminated on the base material may be laminated on the entire surface of the base material, or may be a part.

(Adhesive layer)
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present invention is a pressure-sensitive adhesive layer obtained by removing the solvent from the above pressure-sensitive adhesive, and the temperature showing the peak of loss tangent in the loss tangent curve of the dynamic viscoelastic spectrum at a frequency of 1 Hz is shown. It is an adhesive layer at −15 ° C. to 5 ° C. More preferably, it is −10 ° C. to −5 ° C. When the temperature showing the peak of loss tangent exceeds 5 ° C, the low temperature property deteriorates, and when it is less than -15 ° C, the high temperature property deteriorates.

  The dynamic viscoelasticity of the pressure-sensitive adhesive layer in the present invention is measured between a parallel disk having a diameter of 7.9 mm, which is a measurement part of the testing machine, using a viscoelasticity testing machine (manufactured by Rheometrics, trade name: Ares 2KSTD). , The storage elastic modulus (G ′) and loss elastic modulus (G ″) at a frequency of 1 Hz are measured, and the loss tangent is calculated by the equation represented by tan δ = (G ″) / (G ′). Is done. In the test piece, an adhesive having a thickness of 0.5 to 2.5 mm may be sandwiched between parallel disks alone, or a laminate of a base material and an adhesive may be stacked in layers and sandwiched between parallel disks. In the latter case, the thickness of the pressure-sensitive adhesive alone is adjusted to be in the above range. When the thickness of the pressure-sensitive adhesive is adjusted to the above range, the dynamic viscoelastic spectrum of the pressure-sensitive adhesive can be measured in the same manner as when there is no base material even if the base material is sandwiched between them.

  The pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape of the present invention has a gel fraction of 20% to 60%, preferably 20% to 50%, more preferably 25% to 45%. When the gel fraction is within the above range, the resilience resistance is particularly good.

  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.

  5-50 micrometers is preferable and, as for the thickness of the adhesive layer of the adhesive tape of this invention, More preferably, it is 10-30 micrometers. By setting the thickness to 5 μm or more, the pressure-sensitive adhesive is suitably deformed and excellent resilience resistance is easily obtained. Moreover, by setting it as 50 micrometers or less, it is suitable for the use to the electronic device which a lighter and thinner miniaturization advances.

(Base material)
The base material used for the adhesive tape may be a base material made of a resin film alone, or a base material made of a resin film provided with a light-shielding property or light-reflecting property on the resin film itself. The base material provided with may be sufficient.
As the resin film used for the substrate, for example, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyethylene film, polypropylene film, cellophane, diacetyl cellulose film, triacetyl cellulose film, acetyl cellulose butyrate film, polyvinyl chloride film, Polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyetheretherketone film, polyethersulfone film, polyetherimide film, polyimide film , Fluorine resin film, nylon film, acrylic resin film It can be mentioned Lum and the like.

  In order to improve the adhesion between the resin film and the pressure-sensitive adhesive layer, surface roughening by sandblasting or solvent treatment, corona discharge treatment, chromic acid treatment, flame treatment, hot air treatment, ozone / ultraviolet irradiation treatment Surface treatment such as surface oxidation treatment can be performed.

  The thickness of the substrate is preferably 3 μm to 50 μm, and more preferably 10 μm to 30 μm. If it is 3 μm or more, the processability is good, and if it is 50 μm or less, it can be suitably applied to a pressure-sensitive adhesive tape for LCD modules.

(Light shielding layer)
In order to obtain a base material having a light-shielding property, the resin film can be formed by applying a light-shielding layer, for example, black ink. In order to make the ink layer black, a known and commonly used pigment or dye may be contained. Among these, carbon black is particularly preferable. The ink vehicle is preferably a halogen-free type.

(Light reflecting layer)
In order to obtain a light-reflective substrate, it can be formed by laminating a light-reflective layer on a resin film or by making the resin film itself a light-reflective film. For example, a white pigment or a silver pigment may be dispersed in the resin film to form a white resin film or a silver resin film, or a white ink or silver ink may be coated on the resin film to form a printing film, or a metal vapor deposition layer It is good also as a vapor deposition film by providing. A white resin film is preferably used because of its cost and availability.

(Peeling sheet)
In the pressure-sensitive adhesive tape of the present invention, a release sheet can be provided on the pressure-sensitive adhesive layer as necessary. As this release sheet, paper such as kraft paper, glassine paper and high-quality paper, paper coated with synthetic resin such as polyvinyl alcohol or clay on one or both sides of the paper, or polyethylene resin or the like on one side of the paper Alternatively, a paper laminated on both surfaces, or a plastic film such as polyethylene terephthalate, polyethylene naphthalate, and polypropylene coated with a release agent such as a fluorine resin or a silicone resin on one surface or both surfaces can be used. The thickness of the release sheet is not particularly limited, but is generally in the range of 20 to 300 μm.

(Manufacturing method of adhesive tape)
An adhesive layer can be formed on a base film by the method generally used for application | coating of an adhesive tape. The composition of the pressure-sensitive adhesive layer is applied directly to the base film and dried, or once applied onto the separator, dried and then bonded to the base film.

(Adhesive properties of adhesive tape)
The adhesive strength of the pressure-sensitive adhesive tape of the present invention is preferably 3 to 15 N / 10 mm when only the tape is used for fixing the LCD panel and the backlight housing. When mechanical fixing such as a metal frame is used together, 0.1 to 15 N / 10 mm is preferable.
The adhesive strength of the pressure-sensitive adhesive tape of the present invention was determined by the following procedure according to the JIS-Z0237 (2000) 180-degree peeling adhesive strength test method.

  (1) The 25 mm wide adhesive tapes of Examples and Comparative Examples lined with a polyester film 25 μm were pressure-applied to a polycarbonate with a 2 kg roller under a condition of 23 ° C. and 50% humidity, and left for 1 hour. Thereafter, 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 S25.

(2) The adhesive force S was determined by the following formula. (Adhesive force S is determined as a value converted to N / 10 mm in accordance with JIS Z 8401. Note that S is rounded off to the second decimal place and calculated to the second decimal place.)
S = (10 × S25) ÷ W
Where S: Adhesive strength (N / 10 mm)
S25: Adhesive strength when stripping 25mm wide tape (N)
W: Specimen width (mm)

(Configuration with adhesive layer on base)
The pressure-sensitive adhesive tape of the present invention has a structure having a pressure-sensitive adhesive layer on at least one surface of a base material, and specific embodiments can be exemplified by the structures illustrated in FIGS.

  FIG. 1 is an embodiment in which pressure-sensitive adhesive layers are laminated on both surfaces of a substrate. FIG. 2 shows an embodiment in which an adhesive layer is laminated on one side of a substrate. FIG. 3 shows an embodiment in which a pressure-sensitive adhesive layer is laminated on the light reflection layer side of a substrate in which a light reflection layer and a light shielding layer are laminated. FIG. 4 is an embodiment showing an example of the pressure-sensitive adhesive tape of the present invention in which a pressure-sensitive adhesive layer is provided on both surfaces of a base material on which a light reflecting layer and a light shielding layer are laminated. The pressure-sensitive adhesive tape of the present invention can take the form of a single-sided pressure-sensitive adhesive tape as shown in FIGS. 2 and 3, or a double-sided pressure-sensitive adhesive tape as shown in FIGS. The pressure-sensitive adhesive layer 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. Among these configurations, it is suitable for alleviating the impact applied to the LCD panel, etc., and preventing dust from entering between the members constituting the LCD module. It is preferable that it is the structure which has an adhesive layer on both surfaces.

  In this invention, the adhesive tape which used the base material which provided the adhesive layer on both surfaces of the base material which laminated | stacked the light reflection layer and the light shielding layer illustrated in FIG. 4, and has both light reflectivity and light-shielding property It is preferable that

  When the light-shielding tape of the present invention is applied to an LCD module, in order to shield the entrance of light to the driver that drives the LCD panel and to prevent the malfunction, the light is transmitted through 200 to 1100 nm. The rate is preferably 0.1% or less. Especially, it is most preferable that it is 0.01% or less. The light transmittance was measured using a spectrophotometer V-520-SR type (manufactured by JASCO Corporation), the spectral transmittance in the range of 400 to 700 nm was measured at 10 nm intervals according to JIS Z-8722, and the average was obtained. Calculated as a value (average transmittance).

  When the adhesive tape of this invention has a light reflection layer, it is preferable that the light reflectivity by the side of a light reflection layer is 60% or more. Among them, the visible light reflectance is more preferably 65% or more, and further preferably 70% or more. When the visible light reflectance is 60% or more, the brightness of the LCD panel is preferably increased. In addition, the light reflectance of an adhesive tape may measure the light reflectance in the case where the light reflectance of the light reflection layer itself is measured, and the case where the adhesive layer is laminated | stacked on the light reflection layer. In the case where the pressure-sensitive adhesive layer is laminated on the light reflecting layer, the light reflectance is not the light reflectance value of the light reflecting layer itself, but the light reflectance value including the pressure-sensitive adhesive layer.

  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. Calculated as an average value (average reflectance).

[LCD module]
(Configuration etc.)
The adhesive tape of the present invention is an LCD module having a backlight housing provided with at least one optical film and an LCD panel, and between the optical film and the LCD panel or between the optical film and the backlight housing. Between the body, at least a part of the surface of the pressure-sensitive adhesive layer is used so as to contact the surface of the optical film.

  In the present invention, the LCD module refers to a backlight case provided with at least one optical film and an LCD panel, and the LCD panel and the backlight case are integrated. This refers to a configuration used as an LCD module having a configuration used in a backlight type liquid crystal display device. The backlight housing in the present invention has a configuration in which a light source for backlight is provided and at least one optical film is provided. The pressure-sensitive adhesive tape of the present invention is used in such a manner that at least a part of the pressure-sensitive adhesive layer is in contact with the surface of the optical film.

  Examples of the optical film provided on the surface layer of the backlight housing include a prism sheet, a diffusion film, a light shielding film, and a reflective film.

  The configuration of the LCD module of the present invention includes (1) a configuration in which an optical film is provided on the outermost layer of the backlight housing, and the optical film and the LCD panel are integrated via an adhesive tape. ) An optical film is integrated with a backlight housing via an adhesive tape, and another configuration is laminated on the optical film and an LCD panel is integrated. The adhesive tape used here is for the purpose of securing the image display portion in the configuration of (1), and in the configuration of (2) the purpose is to match the shape of the frame that has been framed to reduce the thickness and weight. In many cases, a frame-like adhesive tape is used.

  As an example of a specific configuration of the LCD module, the side light type backlight type LCD module unit 100 shown in FIG. 5 and FIG. 5 and 6 are schematic views showing a schematic configuration of the LCD module unit 100 in which an adhesive tape is provided between the LCD panel and the backlight housing, FIG. 5 is a sectional view, and FIG. 6 is an exploded view. It is. In general, the LCD module unit 100 includes one or more prisms used as necessary in the backlight housing 16 as a reflection plate 15, a light guide plate 14, a diffusion sheet 12, and an optical film to increase luminance. A sheet 11, an adhesive tape 10, and an LCD panel 17 are laminated in this order, and a light source 13 composed of an LED (Light Emitting Diode) having a lamp reflector or a cold cathode tube is disposed on the side of the light guide plate 14. Yes.

  The adhesive tape provided between the LCD panel 17 and the backlight housing 16 is provided so that the adhesive layer is in contact with the prism sheet 11, and a part of the adhesive layer is also in contact with the backlight housing 16. It is provided as follows. Accordingly, the prism sheet 11 and the diffusion sheet 12 installed below the prism sheet 11 are fixed to the backlight housing. This pressure-sensitive adhesive tape 10 is usually punched into a frame shape, and its width is about 0.5 to 10 mm.

  Further, as a configuration example of the above (2), there is a side light type backlight type LCD module unit 100 ′ shown in FIGS. 7 and 8. 7 and 8 are schematic views showing a schematic configuration of an LCD module unit 100 ′ in which an adhesive tape is provided between the backlight housing and the optical film. The LCD module unit 100 ′ has a configuration in which the adhesive tape is provided between the LCD panel 17 and the backlight housing 16, in addition to the configuration shown in FIGS. It is the structure by which the adhesive tape was provided between the reflecting plates which are two.

  9 and 10 show an LCD module of the present invention in which the adhesive tape of the present invention is used for fixing an LCD panel 17 integrated with a flexible printed circuit board (hereinafter abbreviated as FPC) 18 and a backlight housing. It is the schematic which shows one Embodiment of a unit, FIG. 9 is sectional drawing, Fig.10 (a) is an exploded view, FIG.10 (b) is a general view. The LCD module unit 100 ″ of this embodiment, the backlight housing 16, the LCD panel 17, and the FPC 18 connected integrally to the LCD panel 17 are schematically configured. As shown in FIG. The FPC 18 is bent at about 180 ° in the direction of the arrow, sandwiches the LCD panel 17 and the backlight housing 16, and is fixed to the back surface of the backlight housing 16 with a hook or other adhesive tape. .

  In this configuration, by using the double-sided adhesive tape as the adhesive tape 10, it is possible to configure an LCD module in which the LCD panel does not float against the rebound of the FPC. The other interior of the backlight housing 16 is the same as that shown in FIGS. The FPC 18 is generally a circuit board that can be bent freely with a polyimide film as a base material. Therefore, as shown in FIG. It is possible to sandwich the housing 16. However, since a force that always returns to the horizontal is applied to the FPC 18, an upward repulsive force that the FPC 18 attempts to return to the horizontal is applied to the adhesive tape 10 that fixes the LCD panel 17 and the backlight housing 16. (Indicated by an arrow in FIG. 10B) is always loaded. This repulsive force is greatest in the vicinity where the LCD panel 17 and the FPC 18 are connected, and becomes weaker as the distance L from the vicinity of the connection portion increases.

  This repulsive force was measured by the present inventors using only a spring. As a result, the distance L from the connecting portion was 1 cm to 0.8 to 1.3 N, and the distance L was 4 cm to 0.1 to 0.2 N. It is a small force. And as the distance L increases, the repulsive force becomes weaker. Therefore, what is required of the pressure-sensitive adhesive tape 10 according to the present invention is not a high initial adhesive strength or a high adhesive strength that can withstand a large and high speed peeling, but a length that can withstand a small repulsive force that is always applied permanently. Adhesive strength over time. JIS or the like does not describe such a method for measuring an adhesive force over a long period of time, but it can be approximated by a peeling speed in a constant load peel test. When the peeling speed is 100 mm / hour or less, the LCD panel 17 and the backlight housing 16 that are sandwiched between the FPCs 18 and are constantly loaded with the repulsive force can be fixed with the adhesive tape 10. Does not cause peeling. Further, even if a force corresponding to the repulsive force that the FPC tries to return to the horizontal is always applied to the portion where the parts of the LCD module unit 100 ′ are joined by the adhesive tape 10, the adhesive tape will not peel off. Therefore, it is possible to make it difficult for troubles such as part dropping off to occur.

  Since the LCD module unit 100 ′ having the configuration shown in FIGS. 9 and 10 uses the adhesive tape 10 to fix the LCD panel 17 sandwiched between the FPC 18 and the backlight housing 16, the LCD panel 17 And the backlight housing 16 are not peeled off, and troubles such as parts falling off hardly occur.

  Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

<Preparation of acrylic copolymer (1)>
Preparation of acrylic copolymer In a reaction vessel equipped with a stirrer, cold flow cooler, thermometer, dropping funnel and nitrogen gas inlet, 92.5 parts by weight of n-butyl acrylate, 0.5 parts by weight of 2-hydroxyethyl acrylate, 3.0 parts by weight of vinyl acetate, 2.0 parts by weight of N-vinylpyrrolidone, 2.0 parts by weight of acrylic acid and 0.2 part of 2,2′-azobisisobutylnitrile as a polymerization initiator in 100 parts of ethyl acetate After dissolution and substitution with nitrogen, polymerization was carried out at 80 ° C. for 8 hours to obtain an acrylic copolymer (1).

<Preparation of acrylic copolymer (2)>
Preparation of acrylic copolymer In a reaction vessel equipped with a stirrer, a cold flow condenser, a thermometer, a dropping funnel and a nitrogen gas inlet, 89.5 parts by weight of n-butyl acrylate, 10.0 parts by weight of N-vinylpyrrolidone, -0.5 part by weight of hydroxyethyl acrylate and 0.2 part of 2,2'-azobisisobutylnitrile as a polymerization initiator are dissolved in 100 parts of ethyl acetate, and after substitution with nitrogen, polymerization is carried out at 80 ° C for 8 hours. A copolymer (2) was obtained.

<Preparation of acrylic copolymer (3)>
Preparation of acrylic copolymer In a reaction vessel equipped with a stirrer, cold flow cooler, thermometer, dropping funnel and nitrogen gas inlet, 44.9 parts by weight of butyl acrylate, 50 parts by weight of 2-ethylhexyl acrylate, 2 parts by weight of acrylic acid Then, 3.0 parts by weight of vinyl acetate, 0.1 part by weight of 4-hydroxybutyl acrylate and 0.1 part by weight of 2,2′-azobisisobutylnitrile as a polymerization initiator were dissolved in 100 parts by weight of ethyl acetate. This was polymerized at 70 ° C. for 10 hours to obtain an acrylic copolymer (3) solution.

<Preparation of acrylic copolymer (4)>
Preparation of acrylic copolymer In a reaction vessel equipped with a stirrer, cold flow cooler, thermometer, dropping funnel and nitrogen gas inlet, n-butyl acrylate 84.5 parts by weight, 2-hydroxyethyl acrylate 0.5 parts by weight, 3.0 parts by weight of vinyl acetate, 2.0 parts by weight of N-vinylpyrrolidone, 10.0 parts by weight of acrylic acid and 0.2 part of 2,2′-azobisisobutylnitrile as a polymerization initiator in 100 parts of ethyl acetate After dissolution and substitution with nitrogen, polymerization was carried out at 80 ° C. for 8 hours to obtain an acrylic copolymer (4).

<Preparation of adhesive A>
10 parts by weight of terpene phenol resin YS Polystar T130 (manufactured by Yasuhara Chemical Co., Ltd.) having a softening point of 130 ° C. and 100 parts by weight of the above acrylic copolymer (1), and polymerized rosin ester resin Percene D-135 (Arakawa) having a softening point of 135 ° C. (Chemical Co., Ltd.) was added in an amount of 10 parts by weight and diluted with ethyl acetate to obtain adhesive A having a resin solid content of 45%.

<Preparation of adhesive B>
10 parts by weight of terpene phenol resin YS Polystar T130 (manufactured by Yasuhara Chemical Co., Ltd.) having a softening point of 130 ° C. and 100 parts by weight of the acrylic copolymer (2), and polymerized rosin ester resin Percene D-135 (Arakawa) having a softening point of 135 ° C. Chemical Co., Ltd.) was added in an amount of 10 parts by weight, and diluted with ethyl acetate to obtain a pressure-sensitive adhesive B having a resin solid content of 45%.

<Preparation of adhesive C>
20 parts by weight of terpene phenol resin YS Polystar T130 (manufactured by Yasuhara Chemical Co., Ltd.) having a softening point of 130 ° C. is added to 100 parts by weight of the above acrylic copolymer (1), diluted with ethyl acetate, and adhesive C having a resin solid content of 45% is added. Obtained.

<Preparation of adhesive D>
20 parts by weight of polymerized rosin ester resin Persene D-135 (Arakawa Chemical Co., Ltd.) having a softening point of 135 ° C. is added to 100 parts by weight of the above acrylic copolymer (1), and diluted with ethyl acetate to give a resin solid content of 45%. Agent D was obtained.

<Preparation of adhesive E>
20 parts by weight of a terpene phenol resin YS Polystar T160 (manufactured by Yasuhara Chemical Co., Ltd.) having a softening point of 160 ° C. and 100 parts by weight of the acrylic copolymer (1) and a polymerized rosin ester resin Percene D-135 having a softening point of 135 ° C. (Arakawa) (Chemical Co., Ltd.) was added in an amount of 10 parts by weight, and diluted with ethyl acetate to obtain adhesive E having a resin solid content of 45%.

<Preparation of adhesive F>
5 parts by weight of terpene phenol resin YS Polystar T130 (manufactured by Yasuhara Chemical Co., Ltd.) having a softening point of 130 ° C. and 100 parts by weight of the above acrylic copolymer (1) and a polymerized rosin ester resin Percene D-135 (Arakawa) having a softening point of 135 ° C. 1 part by weight of Chemical) was added and diluted with ethyl acetate to obtain adhesive F having a resin solid content of 45%.

<Preparation of adhesive G>
10 parts by weight of polymerized rosin ester resin Persene D-135 (Arakawa Chemical Co., Ltd.) having a softening point of 135 ° C. is added to 100 parts by weight of the acrylic copolymer (3), diluted with ethyl acetate, and the resin solid content is 45%. The pressure-sensitive adhesive G was obtained.

<Preparation of adhesive H>
10 parts by weight of rosin ester resin A-100 (manufactured by Arakawa Chemical Co., Ltd.) having a softening point of 100 ° C. and 100 parts by weight of the acrylic copolymer (1) and a polymerized rosin ester resin Percene D-135 having a softening point of 135 ° C. 20 parts by weight (manufactured by Arakawa Chemical Co., Ltd.) was added and diluted with ethyl acetate to obtain adhesive H having a resin solid content of 45%.

<Preparation of adhesive I>
10 parts by weight of terpene phenol resin YS Polystar T130 (manufactured by Yasuhara Chemical Co., Ltd.) having a softening point of 130 ° C. and 100 parts by weight of the acrylic copolymer (4), and polymerized rosin ester resin Percene D-135 (Arakawa) having a softening point of 135 ° C. (Chemical Co., Ltd.) was added in an amount of 10 parts by weight, and diluted with ethyl acetate to obtain adhesive I having a resin solid content of 45%.

<Preparation of ink to be a light reflection layer and a light shielding layer>
(Adjustment of white ink used as light reflection layer)
Dainippon Ink & Chemicals, Inc. White ink “Panacia CVL-SP709 White” (vinyl chloride / vinyl acetate) 100 parts, Dainippon Ink & Chemicals “CVL Hardener No. 10”, Dainippon Ink Chemical 35 parts of “Di Reducer V No. 20” manufactured by Kogyo Co., Ltd. was added to prepare white ink.

(Adjustment of black ink used as light shielding layer)
Dainippon Ink & Chemicals, Inc. Sumiink "Panacia CVL-SP805 Sumi" (vinyl chloride / vinyl acetate) 100 parts, Dainippon Ink & Chemicals "CVL Hardener No. 10", 4 parts, Dainippon Ink & Chemicals A black ink was prepared by adding 35 parts of “Die Reducer V No. 20”.

<Preparation of base material>
Teijin DuPont Films Co., Ltd. white PET film “Teflex FW2 # 13” (registered trademark) was corona-treated so that the wetting tension was 5 × 10 ⁻⁴ N / cm, and white ink was dried on the corona-treated surface. Was twice gravure coated so as to be 2 μm.
Subsequently, the black ink was gravure-coated twice on the white ink layer so that the dry thickness was 2 μm. Further, this was cured at 40 ° C. for 2 days to obtain an ink coat film (a).

[Example 1]
To 100 parts by weight of the pressure-sensitive adhesive A, 0.8 parts by weight of an isocyanate-based crosslinking agent (Coronate L-45 manufactured by Nippon Polyurethane Co., Ltd., solid content: 45%) was added, stirred for 15 minutes, and then peel-treated polyester film having a thickness of 75 μm. It was coated so that the thickness after drying was 10 μm, and dried at 85 ° C. for 3 minutes. This was transferred onto both sides of the ink coat film (a). Thereafter, aging was performed at 40 ° C. for 2 days to obtain a double-sided pressure-sensitive adhesive tape having a total thickness of 40 μm. Moreover, the gel fraction of the adhesive layer of this adhesive tape was 38%.

[Example 2]
A double-sided pressure-sensitive adhesive tape having a total thickness of 40 μm was obtained in the same manner as in Example 1 except that 0.5 part by weight of the isocyanate-based crosslinking agent was added instead of 0.8 part by weight. Moreover, the gel fraction of the adhesive layer of this adhesive tape was 28%.

[Comparative Example 1]
A double-sided pressure-sensitive adhesive tape having a total thickness of 40 μm was obtained in the same manner as in Example 1 except that the pressure-sensitive adhesive B was used instead of the pressure-sensitive adhesive A. Moreover, the gel fraction of the adhesive layer of this adhesive tape was 35%.

[Comparative Example 2]
A double-sided pressure-sensitive adhesive tape having a total thickness of 40 μm was obtained in the same manner as in Example 1 except that the pressure-sensitive adhesive C was used in place of the pressure-sensitive adhesive A. Moreover, the gel fraction of the adhesive layer of this adhesive tape was 42%.

[Comparative Example 3]
A double-sided pressure-sensitive adhesive tape having a total thickness of 40 μm was obtained in the same manner as in Comparative Example 1 except that the pressure-sensitive adhesive D was used instead of the pressure-sensitive adhesive A. Moreover, the gel fraction of the adhesive layer of this adhesive tape was 25%.

[Comparative Example 4]
A double-sided pressure-sensitive adhesive tape having a total thickness of 40 μm was obtained in the same manner as in Comparative Example 1 except that the pressure-sensitive adhesive E was used instead of the pressure-sensitive adhesive A. Moreover, the gel fraction of the adhesive layer of this adhesive tape was 35%.

[Comparative Example 5]
A double-sided pressure-sensitive adhesive tape having a total thickness of 40 μm was obtained in the same manner as in Comparative Example 1 except that the pressure-sensitive adhesive F was used in place of the pressure-sensitive adhesive A. Moreover, the gel fraction of the adhesive layer of this adhesive tape was 42%.

[Comparative Example 6]
The total thickness was obtained in the same manner as in Example 1 except that 1.1 parts by weight of the isocyanate-based crosslinking agent was added in place of 0.8 parts by weight instead of the pressure-sensitive adhesive G. A 40 μm double-sided adhesive tape was obtained. Moreover, the gel fraction of the adhesive layer of this adhesive tape was 35%.

[Comparative Example 7]
The total thickness was obtained in the same manner as in Example 1 except that 0.9 parts by weight of the isocyanate-based crosslinking agent was added in place of 0.8 part by weight instead of the adhesive A instead of the adhesive A. A 40 μm double-sided adhesive tape was obtained. Moreover, the gel fraction of the adhesive layer of this adhesive tape was 35%.

[Comparative Example 8]
A double-sided pressure-sensitive adhesive tape having a total thickness of 40 μm was obtained in the same manner as in Example 1 except that the pressure-sensitive adhesive I was used in place of the pressure-sensitive adhesive A. Moreover, the gel fraction of the adhesive layer of this adhesive tape was 35%.

  The pressure-sensitive adhesive solutions and double-sided pressure-sensitive adhesive tapes prepared in Examples 1 and 2 and Comparative Examples 1 to 8 were tested by the method shown below, and the evaluation results are shown in Table 1.

(1) Dynamic viscoelasticity measurement: A cross-linked adhesive was laminated to a thickness of 2 mm to obtain a test piece. A parallel plate having a diameter of 7.9 mm was mounted on a rheometer viscoelasticity tester Ares 2KSTD, a test piece was sandwiched, and a loss tangent from −50 ° C. to 150 ° C. was measured at a frequency of 1 Hz.
(2) Resilience resistance: As shown in FIG. 11, a 100 μm PET film (Embret SA # 100 manufactured by Unitika) and a 2 mm thick polycarbonate (PC) were pasted with a 2 mm width tape. Thereafter, pressurization was performed under the condition of one reciprocation of a 2 kg roller, and floating peeling was observed under the following environmental conditions.
Judgment of floating peeling: ○: floating peeling is less than 0.5 mm, x: floating peeling is 0.5 mm or more.
Environmental conditions High temperature: 85 ° C, 72 hours Cycle: -35 ° C (1 hour) to 85 ° C (1 hour), 100 cycles (1 cycle 4 hours)

  The double-sided pressure-sensitive adhesive tapes of Comparative Examples 1 to 3, 6, and 7 are inferior in resilience resistance because the blending ratio and blending ratio of the acrylic copolymer and tackifying resin, which are essential components, are out of a specific range. In Comparative Examples 4, 5, and 8, the temperature at which the loss tangent peak in the loss tangent curve of the dynamic viscoelastic spectrum at a frequency of 1 Hz of the pressure-sensitive adhesive layer is out of the specific range is inferior in resilience resistance. On the other hand, it can be seen that the double-sided pressure-sensitive adhesive tapes of Examples 1 and 2 have excellent resilience resistance.

It is a conceptual sectional view showing one embodiment of the double-sided adhesive tape of the present invention. It is a conceptual sectional view showing one embodiment of the double-sided adhesive tape of the present invention. It is a conceptual sectional view showing one embodiment of the double-sided adhesive tape of the present invention. It is a conceptual sectional view showing one embodiment of the double-sided adhesive tape of the present invention. It is sectional drawing which shows schematic structure of the LCD module unit which provided the adhesive tape between the LCD panel and the backlight housing | casing. It is an exploded view which shows schematic structure of the LCD module unit which provided the adhesive tape between the LCD panel and the backlight housing | casing. It is sectional drawing which shows one Embodiment of the LCD module unit which provided the double-sided adhesive tape between the optical film and the backlight housing | casing. It is an exploded view which shows schematic structure of the LCD module unit which provided the adhesive tape between the optical film and the backlight housing | casing. It is sectional drawing which shows one Embodiment of the LCD module unit which used the double-sided adhesive tape for adhering with the LCD panel integrated with FPC, and a backlight housing | casing. It is the schematic which shows one Embodiment of the LCD module unit which used the double-sided adhesive tape for fixation with the LCD panel integrated with FPC, and a backlight housing | casing, (a) is an exploded view, (b) is the whole FIG. It is a conceptual diagram which shows the measuring method of resilience resistance.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1: Adhesive layer 2: Base material 3: Light-shielding layer 4: Light reflection layer 9: Driver 10: Adhesive tape 11: Prism sheet 12: Diffusion sheet 13: Light source 14: Light guide plate 15: Reflection plate 16: Backlight housing 17: LCD panel 18: FPC
19: Direction of repulsive force 20: Adhesive tape 21: Brightness enhancement film 22: Glass 23: PC board 24: PET film 25: Double-sided tape

Claims (8)

An adhesive tape having an adhesive layer on at least one surface of a substrate,
The pressure-sensitive adhesive layer comprises a pressure-sensitive adhesive containing an acrylic copolymer and a tackifying resin,
The acrylic copolymer contains 0.1 to 3% by mass of a nitrogen-containing vinyl monomer as a monomer component,
Containing a polymerized rosin ester-based resin having a softening point of 80-150 ° C. and a terpene phenol-based resin having a softening point of 100-150 ° C. as the tackifier resin;
A pressure-sensitive adhesive tape, wherein a temperature at which a loss tangent peak in a loss tangent curve of a dynamic viscoelastic spectrum at a frequency of 1 Hz of the pressure-sensitive adhesive layer is −15 ° C. to 5 ° C. The content of the terpene phenol resin is 0.1 to 0.3 by mass ratio with respect to the acrylic copolymer, and the content of the polymerized rosin ester resin is 0.1 mass ratio with respect to the terpene phenol resin. It is -1.5, The adhesive tape of Claim 1. The pressure-sensitive adhesive tape according to claim 1 or 2, wherein the pressure-sensitive adhesive layer has a gel fraction of 20 to 60%. The pressure-sensitive adhesive tape according to any one of claims 1 to 3, which has a thickness of 100 µm or less. The acrylic copolymer is 50% by mass or more of a (meth) acrylic acid alkyl ester monomer having an alkyl group having 1 to 14 carbon atoms as a monomer component, and 0.01% of a vinyl monomer having a functional group that reacts with a crosslinking agent. The adhesive tape in any one of Claims 1-4 containing -0.5 mass%. The adhesive tape according to any one of claims 1 to 5, wherein the adhesive tape is used by being stuck between an LCD panel of an LCD module and a backlight casing. The pressure-sensitive adhesive tape according to any one of claims 1 to 6, wherein the backlight-side pressure-sensitive adhesive layer is 10% or more thicker than the LCD panel-side pressure-sensitive adhesive layer. An LCD module, wherein the adhesive tape according to claim 1 is adhered between an LCD panel and a backlight housing.

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