JP2017057304A - Shading adhesive tape, manufacturing method therefor, and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an industrially useful shading adhesive tape capable of being used for adhesion of various adherends and having excellent peel adhesive force and excellent static load holding force.SOLUTION: A shading adhesive tape has an adhesive layer (A) with tensile strength of 6 N/cmor more based on a stress-strain curve (i.e. S-S curve) at a strain amount of 100% on single side or double side of a substrate.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light-shielding pressure-sensitive adhesive tape, and relates to a light-shielding pressure-sensitive adhesive tape that can be used in various situations including, for example, fixing of a casing having a backlight and a liquid crystal display.

  Liquid crystal display devices are used in various fields including portable electronic terminals such as smartphones.

  As a typical configuration of the liquid crystal display device, for example, a configuration including a liquid crystal display panel on which a light guide plate, a reflection plate, a liquid crystal display panel, or the like is mounted on a casing provided with a light source (backlight) can be given. In many cases, the liquid crystal display panel and the case are fixed by a light-shielding adhesive tape processed into a frame shape or the like, and the light-shielding adhesive tape is an optical element such as a prism sheet constituting a part of the case. Often attached to the surface of a film.

  In addition to simply fixing the liquid crystal display or the like to the light-shielding adhesive tape, the appearance of the liquid crystal display device is improved and the light from the backlight enters the integrated circuit (IC). In order to prevent malfunctions, high light shielding properties are often required.

  The pressure-sensitive adhesive tape having excellent light-shielding property is, for example, a pressure-sensitive adhesive tape having both light reflectivity and light-shielding property, which is used by being attached between an LCD panel of an LCD module and a backlight case. It has a support formed by laminating a reflective layer and a light shielding layer, and an adhesive layer provided on at least one surface of the support, and the light reflective layer has a thickness of 10 to 30 μm and 10.0 N / 10 mm. An adhesive tape composed of a white resin film having the above tensile strength is known (see, for example, Patent Document 1).

  However, the thin optical film to which the light-shielding adhesive tape is attached is attributed to a backlight or the like, while the liquid crystal display device is required to be thin also for members such as an optical film constituting the liquid crystal display device. In some cases, distortion may occur due to the influence of heat.

  In addition, there are various application scenes of the light shielding adhesive tape, and the light shielding adhesive tape is required to have various characteristics according to the application scene. As the above-mentioned characteristics, for example, even when a certain stress caused by strain or the like is applied to a portion joined using a light-shielding adhesive tape over a long period of time, floating or peeling that is a practical problem is caused. Durability (static load holding force) that does not cause and peel adhesive strength are mentioned. Here, the excellent static load holding force means that the adherend is bonded using a light-shielding adhesive tape, and when a certain load is applied in a direction perpendicular to the bonding surface, It means that it does not easily cause lifting or peeling over time.

  In particular, as the portable electronic terminal and the like become larger and thinner, the light-blocking adhesive tape has a smaller application area and the width of the light-blocking adhesive tape is reduced. Although there was a demand for tape, it was not found yet.

JP 2004-156015 A

  The problem to be solved by the present invention is that it can suppress distortion over time of thin adherends such as optical films, and has excellent light shielding properties, excellent peel adhesive strength and excellent static load. It is providing the light-shielding adhesive tape provided with the retention strength.

  The present inventors only improve the peel adhesive force by using a light-shielding pressure-sensitive adhesive tape having a pressure-sensitive adhesive layer having a tensile strength obtained from a stress-strain curve (so-called SS curve) of a predetermined value or more. In addition, the present inventors have found that the static load holding force can be remarkably improved, and distortion over time of a thin adherend such as an optical film can be suppressed.

That is, the present invention is characterized in that the pressure-sensitive adhesive layer (A) having a tensile strength of 6 N / cm ² or more based on a stress-strain curve at a strain amount of 100% is provided on at least one surface side of the light shielding substrate. It relates to a light-shielding adhesive tape.

  The light-shielding pressure-sensitive adhesive tape of the present invention can suppress distortion over time of thin adherends such as optical films, and also has excellent light-shielding properties, excellent peel adhesion, and excellent static load retention. Therefore, it can be suitably used in the manufacturing scene of information display devices such as liquid crystal display devices. In particular, the light-shielding adhesive tape can be used for fixing a casing provided with a backlight and a liquid crystal display panel, which constitutes a liquid crystal display device, a part of an optical film constituting the casing, and a liquid crystal It can be suitably used for bonding with a display panel.

The stress-strain curve of the adhesive layer which comprises the light shielding adhesive tape obtained in Example 2 is represented.

The light-shielding pressure-sensitive adhesive tape of the present invention has a pressure-sensitive adhesive layer (A) having a tensile strength of 6 N / cm ² or more based on a stress-strain curve at a strain amount of 100% on one side or both sides of a substrate. To do.

As the pressure-sensitive adhesive layer (A) constituting the light-shielding pressure-sensitive adhesive tape of the present invention, one having a tensile strength based on a stress-strain curve at a strain amount of 100% is 6 N / cm ² or more.

  Here, the tensile strength was obtained by laminating a test piece made of an adhesive layer having a thickness of about 400 μm, a marked line interval of 2 cm, and a width of 1 cm obtained by laminating a 50 μm thick adhesive layer at a temperature of 23 ° C. and humidity. When the amount of strain is 100% in a stress-strain curve (so-called SS curve) measured by a tensile test at a tensile speed of 300 mm / min using a tensile tester in a measurement environment of 50%. Refers to the tensile strength of

Here, in the light-shielding pressure-sensitive adhesive tape provided with the pressure-sensitive adhesive layer having a tensile strength of less than 6 N / cm ² , it is possible to achieve both excellent peel adhesive force, static load holding force, and suppression of prism sheet waviness. There are cases where it is not possible.

The upper limit of the tensile strength is not particularly limited, is preferably 30 N / cm ² or less, more preferably 25 N / cm ² or less, it is 20 N / cm ² or less, including the optical film It is more preferable to suppress the time-dependent distortion of the thin adherend and to exhibit the performance of the light-shielding pressure-sensitive adhesive tape including a peel adhesive force and a static load holding force in a well-balanced manner.

The upper limit of the tensile strength is not particularly limited, but is preferably 7 N / cm ² or more, and 8 N / cm ² or more is the strain over time of thin adherends including optical films. In addition, it is more preferable in that the performance of the light-shielding pressure-sensitive adhesive tape including the peel adhesive force and the static load holding force can be expressed in a well-balanced manner.

  The pressure-sensitive adhesive layer (A) preferably has a thickness of 1 μm to 150 μm, more preferably 5 μm to 100 μm, and more preferably 10 μm to 80 μm. It is more preferable to use what has it, and it is further more preferable to use what has a thickness of 10 micrometers-30 micrometers in order to suppress the distortion | strain with time of thin adherends including an optical film.

  The pressure-sensitive adhesive layer (A) can be formed using various pressure-sensitive adhesives. Especially, as said adhesive layer (A), it is an adhesive layer formed using the adhesive containing an acrylic polymer (a1), tackifying resin (a2), and a crosslinking agent (a3), for example. It is preferable for forming a pressure-sensitive adhesive layer having a specific tensile strength.

Moreover, as said adhesive layer (A), it is preferable to use the thing whose tensile strength based on the stress-strain curve in the strain amount of 500% is 12 N / cm < ² > or more, and uses 13 N / cm < ² > or more. it is more preferable to, more preferably the use of 15N / cm ² or more of, more preferably the use of 17N / cm ² or more of, it is particularly preferred to use 19N / cm ² or more of . The upper limit of the tensile strength is preferably at 70N / cm ² or less, it is more preferable to use those 65N / cm ² or less. By using a pressure-sensitive adhesive layer having a tensile strength based on a stress-strain curve at a strain amount of 500% within the above range, it is possible to suppress strain over time of thin adherends such as optical films. In addition, it is more preferable for expressing the performance of the light-shielding pressure-sensitive adhesive tape including a peel adhesive force, a static load holding force, and impact resistance in a well-balanced manner.

  As the acrylic polymer (a1) that may be contained in the pressure-sensitive adhesive, the tensile strength of the pressure-sensitive adhesive layer (A) is set to a specific range, and as a result, a thin film such as an optical film is attached. An acid value in the range of 1 to 50 can be used to form a pressure-sensitive adhesive layer that can suppress the strain of the body over time and has an even better peel adhesion and excellent static load retention. It is preferable to use those having an acid value in the range of 10 to 50, more preferable to use those having an acid value in the range of 25 to 40, and even more preferable to use those having an acid value in the range of 25 to 40. The acid value is preferably an acid value derived exclusively from a carboxyl group. In addition, the said acid value points out mg of potassium hydroxide required in order to neutralize the acid group which exists in the said acrylic polymer (a1) solution.

  Further, as the acrylic polymer (a1), an acrylic polymer (a1) having an aliphatic cyclic structure is used for forming a pressure-sensitive adhesive layer having even better peel adhesion and excellent static load retention. It is preferable.

  Examples of the aliphatic cyclic structure include a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a propylcyclohexyl group, a tricyclo [5,2,1,0,2,6] decyl group, and a bicyclo [ 4,3,0] -nonyl group, tricyclo [5,3,1,1] dodecyl group, propyltricyclo [5,3,1,1] dodecyl group, norbornene group, isobornyl group, dicyclopentanyl group, An adamantyl group and the like can be mentioned, and among them, a cyclohexyl group, a norbornene group, an isobornyl group, and an adamantyl group can provide a light-shielding pressure-sensitive adhesive tape having an even better peel adhesion and an even better static load holding force. In addition, it is preferable.

  Moreover, as said acrylic polymer (a1), what has a weight average molecular weight of 960,000 or more uses the light-shielding adhesive tape provided with the much more excellent peel adhesive force and the outstanding static load holding power. It is preferable to obtain, more preferably one having a weight average molecular weight in the range of 980,000 to 3,000,000, more preferably one having a weight average molecular weight in the range of 1,000,000 to 3,000,000. Using a material having a weight average molecular weight in the range of 10,000 to 2,200,000 can set the tensile strength of the pressure-sensitive adhesive layer (A) in a specific range, and can be used for thin adherends such as optical films. It is further preferable for obtaining a light-shielding pressure-sensitive adhesive tape that can suppress distortion over time and that has both excellent peel adhesive strength and excellent static load retention. In particular, by using an acrylic polymer having a weight average molecular weight in the above range, the static load holding force of the pressure-sensitive adhesive layer (A) can be remarkably improved. In addition, the said weight average molecular weight is a weight average molecular weight in standard polystyrene conversion measured with a gel permeation chromatograph (GPC).

  The molecular weight is measured by the GPC method using a Tosoh Corporation GPC apparatus (HLC-8329GPC) and converted to polystyrene.

Sample concentration: 0.5% by mass (tetrahydrofuran solution)
Sample injection volume: 100 μl
Eluent: THF
Flow rate: 1.0 ml / min Measurement temperature: 40 ° C
This column: TSKgel GMHHR-H (20) 2 Guard column: TSKgel HXL-H
Detector: differential refractometer Standard polystyrene molecular weight: 10,000 to 20 million (manufactured by Tosoh Corporation)

  As said acrylic polymer (a1), it is preferable to use what has a glass transition temperature of -15 degrees C or less, and it is an optical film to use what has a glass transition temperature of -45 degreeC--20 degreeC. It is more preferable to obtain a light-shielding pressure-sensitive adhesive tape that can suppress the strain with time of thin adherends such as and that has further excellent peel adhesion and excellent static load retention. . The glass transition temperature refers to a calculated value calculated by the FOX equation.

  The acrylic polymer (a1) is preferably contained in an amount of 50% by mass to 95% by mass and preferably 60% by mass to 90% by mass with respect to the entire pressure-sensitive adhesive layer (A). It is more preferable for maintaining workability.

  As said acrylic polymer (a1), it is preferable to use what has a structural unit derived from each vinyl monomer formed after the vinyl monomer component mentioned later carries out a polymerization reaction. Examples of the structural unit include the following general formula (1).

X and R in the formula (1) indicate a functional group corresponding to a vinyl monomer described later, X is a hydrogen atom or a methyl group, R is a hydrogen atom, an alkyl group, an alkanol group, and the like. For example, in the case of n-butyl acrylate, X is a hydrogen atom and R is an n-butyl group, and in the case of 4-hydroxybutyl acrylate, X is a hydrogen atom and R is a —CH ₂ CH ₂ CH ₂ CH ₂ OH group. In the case of acrylic acid, X and R are hydrogen atoms.

  The acrylic polymer (a1) is preferably contained in an amount of 5% by mass to 80% by mass and preferably 10% by mass to 50% by mass with respect to the total amount of the adhesive that can be used for forming the adhesive layer (A). It is more preferable to maintain good coating workability.

  As the vinyl monomer component, in forming an adhesive layer having a predetermined tensile strength, a vinyl monomer having a nitrogen atom such as N-vinyl-2-pyrrolidone, vinyl acetate, styrene, etc. The content of vinyl monomers other than (meth) acrylic monomers is 5% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less, based on the total amount of the vinyl monomer components. A vinyl monomer mixture can be used.

  The vinyl monomer component may be an alkyl having a homopolymer glass transition temperature of 100 ° C. or higher with respect to the total amount of the vinyl monomer component in forming an adhesive layer having a predetermined tensile strength. The total content of (meth) acrylate is preferably 1% by mass or less, more preferably 0.5% by mass or less, and 0.1% by mass or less. It is particularly preferred to use it. Specific examples of the alkyl (meth) acrylate having a glass transition temperature of 100 ° C. or higher include methyl methacrylate.

  As the vinyl monomer, for example, a vinyl monomer having a hydroxyl group, a vinyl monomer having an acid group, an alkyl (meth) acrylate, or the like can be used.

  Examples of the vinyl monomer having a hydroxyl group that can be used in producing the acrylic polymer (a1) include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 3-hydroxypropyl (meth). Acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxyhexyl (meth) acrylate, 6-hydroxyhexyl (meth) acryl, 8-hydroxyoctyl (meth) acrylate, 10-hydroxy (Meth) acrylic monomers having a hydroxyl group such as decyl (meth) acrylate and 12-hydroxylauryl (meth) acrylate can be used.

  Among these, as the vinyl monomer having a hydroxyl group, 4-hydroxybutyl (meth) acrylate is preferably used, and 4-hydroxybutyl acrylate is preferably used as 2-hydroxyethyl (meth) acrylate or the like. Compared to the case where it is used, it is easy to form a pressure-sensitive adhesive layer having a predetermined tensile strength, and as a result, it is possible to suppress distortion over time of thin adherends including optical films, And it is more preferable when obtaining the light-shielding adhesive tape provided with the much more excellent peel adhesive force and the still more excellent static load holding power.

  The vinyl monomer having a hydroxyl group is preferably used in a range of 0.01% by mass to 0.2% by mass with respect to the total amount of the vinyl monomer component, and 0.01% by mass or more and 0.1% by mass. More preferably, it is used in a range of less than mass%, and in the range of 0.02 mass% to 0.08 mass%, the tensile strength of the pressure-sensitive adhesive layer (A) is set to a specific range, and is optical. To obtain a light-shielding pressure-sensitive adhesive tape that can suppress distortion over time of thin adherends such as films, and that has even better peel adhesion and even better static load retention. And more preferable.

  Examples of the vinyl monomer having an acid group that can be used for producing the acrylic polymer (a1) include acrylic acid, methacrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, and (anhydrous). (Meth) acrylic monomers having carboxyl groups such as itaconic acid, (anhydrous) maleic acid, fumaric acid, crotonic acid, (meth) acrylamide propanesulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfone Vinyl monomers having a sulfonic acid group such as acid, sodium vinyl sulfonate, styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, 2- Hydroxyethyl acryloy Having a phosphoric acid group such as a phosphate (meth) can be used acrylic monomers and the like. Among these, it is preferable to use a (meth) acrylic monomer having a carboxyl group, and the use of acrylic acid or methacrylic acid suppresses distortion over time of thin adherends such as optical films. It is more preferable for obtaining a light-shielding pressure-sensitive adhesive tape that can be used and has an even better peel adhesive strength and a more excellent static load holding force.

  The vinyl monomer having an acid group is not particularly limited as long as the acid value of the acrylic polymer (a1) is within a predetermined preferable range, but is 1% by mass with respect to the total amount of the monomer components. It is preferably used in the range of -30% by mass, more preferably in the range of 1% by mass to 15% by mass, and in the range of 1% by mass to 7% by mass, including optical films. It is more preferable for obtaining a light-shielding pressure-sensitive adhesive tape that can suppress the distortion of a thin adherend over time and has a further excellent peel adhesive force and a further excellent static load holding force.

  Further, when the acrylic polymer (a1) is produced, a vinyl monomer having an aliphatic cyclic structure is used as the vinyl monomer component in introducing the aliphatic cyclic structure into the acrylic polymer (a1). It is preferable to use a monomer.

  As the vinyl monomer having an aliphatic cyclic structure, cyclohexyl (meth) acrylate or the like is preferably used, and cyclohexyl acrylate is more preferably used.

  The vinyl monomer having an aliphatic cyclic structure has a predetermined tensile strength when used in a range of 0.5% by mass to 30% by mass with respect to the total amount of the vinyl monomer component. It is easy to form a pressure-sensitive adhesive layer, can suppress distortion over time of thin adherends such as optical films, and has even better peel adhesion and better static load retention It is preferable to obtain a light-shielding pressure-sensitive adhesive tape comprising: and more preferably used in the range of 4% by mass to 25% by mass.

  As a vinyl monomer component that can be used for the production of the acrylic polymer (a1), other monomers can be used as necessary in addition to the above-described ones.

  Examples of the other vinyl monomers include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, and isobutyl (meth) ) Acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) ) Acrylate, isodecyl (meth) acrylate, n-undecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate and other alkyl (meth) acrylates It can be used in a range that does not impair the effects of the invention.

  Among the above-mentioned other vinyl monomers, it is preferable to use alkyl (meth) acrylates having 4 to 12 carbon atoms in the alkyl group, and n-butyl acrylate and 2-ethylhexyl acrylate are used. Can suppress distortion with time of thin adherends such as optical films, and also has light shielding with a better peel adhesion and a better static load holding force. It is preferable when obtaining an adhesive tape.

  Among the alkyl (meth) acrylates usable as the other vinyl monomers, alkyl (meth) acrylates having an alkyl group having 4 to 12 carbon atoms are used for the production of the acrylic polymer (a1). It is preferably used in the range of 50% by mass to 98% by mass, more preferably in the range of 60% by mass to 98% by mass, and 70% by mass to 96% by mass with respect to the total amount of monomer components to be produced. Can be used to suppress distortion over time of thin adherends such as optical films, and more excellent peel adhesion and even better static load retention It is preferable when obtaining the light shielding adhesive tape provided with.

  The n-butyl acrylate is preferably used in the range of 55% by mass to 98% by mass and more preferably in the range of 57% by mass to 98% by mass with respect to the total amount of the vinyl monomer component. More preferably, it is used in the range of 60% by mass to 90% by mass, and the use in the range of 60% by mass to 80% by mass causes a deviation even in a relatively high temperature environment. It is further preferable to obtain a light-shielding pressure-sensitive adhesive sheet having a static load holding force of a level that is not.

  On the other hand, 2-ethylhexyl acrylate is preferably used in the range of 0% by mass to 50% by mass and more preferably in the range of 0% by mass to 30% by mass with respect to the total amount of the vinyl monomer component. Preferably, it is used in the range of 0% by mass to 20% by mass, more preferably in the range of 2% by mass to 10% by mass, even if it is in a relatively high temperature environment. It is further preferable to obtain a light-blocking pressure-sensitive adhesive sheet that has a static load holding force that does not cause it and that can effectively prevent the waviness of the optical film.

  Moreover, as another vinyl monomer which can be used for manufacture of the acrylic polymer (a1), for example, an acrylic monomer having an amide group, a (meth) acrylic monomer having an amino group, and an imide group are included. You may use the (meth) acryl monomer which has nitrogen atoms, such as a (meth) acryl monomer, in the range which does not impair the effect of this invention.

  Examples of the (meth) acrylic monomer having an amide group include acrylamide, methacrylamide, diethylacrylamide, N-vinylpyrrolidone, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide. N, N-diethylmethacrylamide, N, N′-methylenebisacrylamide, N, N-dimethylaminopropylacrylamide, N, N-dimethylaminopropylmethacrylamide, diacetoneacrylamide, acryloylmorpholine and the like can be used. .

  As the (meth) acrylic monomer having an amino group, for example, aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate or the like is used. be able to.

  As the (meth) acrylic monomer having an imide group, for example, cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, itaconimide and the like can be used.

  As the other vinyl monomer, in addition to the above, for example, cyano group-containing monomers such as acrylonitrile and methacrylonitrile, glycidyl groups such as glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and allyl glycidyl ether Containing acrylic monomer, vinyl acetate, vinyl propionate, vinyl laurate, styrene, chlorostyrene, chloromethyl styrene, α-methyl styrene, other substituted styrene, methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, etc. You may use in the range which does not impair an effect.

  The acrylic polymer (a1) can be produced, for example, by supplying the vinyl monomer component and radically polymerizing them in the presence of an organic solvent. Specifically, the acrylic polymer (a1) is radically polymerized by mixing and stirring the vinyl monomer component, the polymerization initiator, and the organic solvent, preferably at a temperature of 40 ° C. to 90 ° C. Can be manufactured. The vinyl monomer component may be supplied all at once or dividedly supplied.

  Examples of the polymerization initiator include peroxides such as hydrogen peroxide, potassium persulfate, sodium persulfate, ammonium persulfate, benzoyl peroxide, cumene hydroxy peroxide, and 2,2′-azobis (2-methylbutyro Nitrile), 2,2′-azobis- (2-aminodipropane) dihydrochloride, 2,2′-azobis- (N, N′-dimethyleneisobutylamidine) dihydrochloride, 2,2′-azobis { An azo compound such as 2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide} or the like can be used. The amount of the polymerization initiator used is preferably in the range of 0.01% by mass to 5% by mass with respect to the total amount of the vinyl monomer component.

  As the pressure-sensitive adhesive that can be used in the present invention, it is possible to suppress the distortion with time of thin adherends including optical films, and to further improve the peel adhesive strength and further excellent In order to obtain a light-shielding pressure-sensitive adhesive tape having a static load holding force, it is preferable to use one containing a tackifying resin (a2).

  Examples of the tackifying resin (a2) include a rosin-based tackifying resin, a polymerized rosin-based tackifying resin, a polymerized rosin ester-based tackifying resin, a rosin phenol-based tackifying resin, a stabilized rosin ester-based tackifying resin, Use of rosin ester-based tackifier resin, hydrogenated rosin ester-based tackifier resin, terpene-based tackifier resin, terpene phenol-based tackifier resin, petroleum resin-based tackifier resin, (meth) acrylate-based tackifier resin, etc. Can do.

  Among them, the tackifier resin (a2) is selected from the group consisting of a polymerized rosin ester tackifier resin, a disproportionated rosin ester tackifier resin, a petroleum tackifier resin, and a terpene phenol tackifier resin. It is preferable to use a combination of two or more species in order to obtain a light-shielding pressure-sensitive adhesive tape having excellent compatibility with the acrylic polymer (a1), and having further excellent peel adhesive strength and still more excellent static load holding power. .

  The softening point of the tackifying resin (a2) is preferably 100 ° C. or higher, and using a resin having a softening point in the range of 120 ° C. to 170 ° C. has an even better peel adhesion and a more excellent static load holding force. It is more preferable for obtaining a light-shielding pressure-sensitive adhesive tape.

  The tackifying resin (a2) is preferably used in the range of 5 to 60 parts by mass with respect to 100 parts by mass of the acrylic polymer (a1), and used in the range of 10 to 50 parts by mass. Can suppress distortion over time of thin adherends such as optical films, and has light-shielding adhesive with even better peel adhesion and even better static load retention. It is more preferable for obtaining a tape.

  Moreover, as said adhesive, when forming the adhesive layer provided with the further outstanding cohesion force, it is preferable to use what contains a crosslinking agent (a3).

  As said crosslinking agent (a3), an isocyanate type crosslinking agent, an epoxy-type crosslinking agent, a metal chelate type crosslinking agent, an aziridine type crosslinking agent etc. can be used, for example. Especially, as said crosslinking agent, it is easy to mix and use the said acrylic polymer (a1) or its solution manufactured previously, and it is possible to use the crosslinking agent which can advance a crosslinking reaction rapidly. Specifically, it is more preferable to use an isocyanate crosslinking agent or an epoxy crosslinking agent.

  Examples of the isocyanate-based crosslinking agent include tolylene diisocyanate, naphthylene-1,5-diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, tolylene diisocyanate, and their trimethylolpropane adducts, triphenylmethane isocyanate, and the like. Can be used. Especially, as said isocyanate type crosslinking agent, it is preferable to use tolylene diisocyanate, these trimethylol propane adducts, triphenylmethane isocyanate, etc.

  As an index of the degree of crosslinking of the pressure-sensitive adhesive layer (A) formed using the pressure-sensitive adhesive containing the cross-linking agent (a3), the insoluble content after the pressure-sensitive adhesive layer (A) was immersed in toluene for 24 hours was measured. The value of the gel fraction to do is mentioned. The gel fraction is preferably in the range of 20% by mass to 70% by mass, more preferably in the range of 20% by mass to 50% by mass, and in the range of 30% by mass to 47% by mass. There is a light-blocking pressure-sensitive adhesive that can suppress distortion over time of thin adherends such as optical films and that has even better peel adhesion and even better static load retention. It is more preferable for obtaining a tape.

  In addition, the said gel fraction points out the value measured by the method shown below.

  The pressure-sensitive adhesive is applied to one side of an arbitrary release liner so that the thickness after drying is 50 μm, dried at 100 ° C. for 3 minutes, and aged at 40 ° C. for 2 days to form a pressure-sensitive adhesive layer To do. A sample cut into a 50 mm square is used as a sample.

  Next, after measuring the mass (G1) of the sample, the sample is immersed in a toluene solution at 23 ° C. for 24 hours. The toluene-insoluble part of the sample after the immersion is separated by filtration through a 300 mesh wire net, and the mass (G2) of the residue after drying at 110 ° C. for 1 hour is measured, and the gel fraction is determined according to the following formula: .

  Gel fraction (mass%) = (G2 / G1) × 100

  As said adhesive, what contains the other component other than what was mentioned above as needed can be used.

  Examples of the other components include plasticizers, softeners, antioxidants, flame retardants, glass and plastic fibers, balloons and beads, fillers such as metals, metal oxides, and metal nitrides, pigments and dyes, and the like. Additives such as colorants, leveling agents, thickeners, water repellents and antifoaming agents can be used.

  Moreover, as said adhesive, when providing favorable coating workability | operativity, it is preferable to use what contains a solvent as needed other than the said acrylic polymer (a1). As said solvent, aqueous media, such as an organic solvent and water, etc. are mentioned, for example.

  Examples of the organic solvent include toluene, ethyl acetate, butyl acetate, methyl ethyl ketone, hexane, acetone, cyclohexanone, 3-pentanone, acetonitrile, propionitrile, isobutyronitrile, valeronitrile, dimethyl sulfoxide, dimethylformamide, and the like. be able to.

As the light-shielding substrate constituting the light-shielding pressure-sensitive adhesive tape of the present invention, those having a light-shielding property at a level capable of shielding light from a backlight constituting a liquid crystal display device can be used.

Here, the light shielding property, it is preferable to refer to those light transmission amount of when irradiated with light of 10000 cd / ^{m 2} is 10 cd / ^{m 2} or less, it is preferable the lower limit is 0 cd / ^{m 2.}

As the light-shielding substrate, a resin film having a light-shielding layer on one surface or both surfaces, or a light-shielding film in which a pigment or dye capable of imparting light-shielding properties and a resin are kneaded can be used. As the light-shielding substrate, it is preferable to use a light-shielding substrate having a light-shielding layer on one side or both sides of the resin film, in order to obtain a light-shielding pressure-sensitive adhesive tape having an excellent static load holding force.
Examples of the resin film include polyethylene terephthalate film (hereinafter abbreviated as PET film), polyester film such as triacetyl cellulose film, polyarylate film, polyimide film, polyether film, polycarbonate film, polysulfone film, polyethersulfone film, A cellophane film, an aromatic polyamide film, a polyethylene film, a polypropylene film, and the like can be used, and it is preferable to use a PET film in order to obtain a light-shielding pressure-sensitive adhesive tape having excellent static load retention in a thermal environment.
As the resin film, one having a thickness of 1 μm to 45 μm is preferably used, and one having a thickness of 10 μm to 30 μm has good workability and good static load. It is preferable for obtaining a light-shielding pressure-sensitive adhesive tape having a holding force.

  Examples of the light shielding layer include a layer formed using black ink containing carbon black or the like. As the ink, an ink containing a vehicle and a pigment or a dye can be used, and it is preferable to use a so-called halogen-free ink.

  As the ink, for example, Sumiink “Panacia CVL-SP805 Sumi” manufactured by DIC Corporation can be used.

  The light-shielding substrate having a light-shielding layer on one or both sides of the resin film can be produced, for example, by the following method. First, one side of the PET film is corona-treated so that the wetting tension is 50 dyne / cm, and the black ink is gravure-coated twice on the corona-treated surface and dried to form a total light-shielding layer of 3 μm. To do. Next, the other surface of the PET film is corona-treated by the same method as described above, and the black ink is gravure-coated twice on the corona-treated surface and dried to form a light-shielding layer having a total thickness of 3 μm. The light shielding base material which has a light shielding layer on both surfaces of resin films, such as PET film, can be obtained by the above method.

  As the light-shielding substrate, it is preferable to use a substrate having a total thickness of 3 μm to 50 μm, and it is preferable to use a substrate having a total thickness of 10 μm to 30 μm with good workability and good static load retention. It is preferable for obtaining a light-shielding pressure-sensitive adhesive tape having strength.

  The light-shielding pressure-sensitive adhesive tape of the present invention is, for example, a method (direct method) for forming the pressure-sensitive adhesive layer (A) by applying the pressure-sensitive adhesive and drying on at least one surface side of the light-shielding base material. A step of forming the pressure-sensitive adhesive layer (A) by applying the pressure-sensitive adhesive to a mold liner and drying, a method of transferring the pressure-sensitive adhesive layer (A) to at least one surface of the light-shielding substrate (transfer method) Can be manufactured by.

  Examples of the method for applying the pressure-sensitive adhesive include a method using a knife coater, a roll coater, a die coater, or the like.

  Drying after the coating can be performed at 85 ° C. for 2 minutes.

As a more preferable production method of the light-shielding pressure-sensitive adhesive tape of the present invention, for example, the total content of vinyl monomers other than the (meth) acrylic monomer with respect to the total amount of vinyl monomer components is 5% by mass or less and Acrylic polymer (a1) having a weight average molecular weight of 1,000,000 to 3,000,000 by polymerizing a vinyl monomer mixture in which the content of alkyl (meth) acrylate having a glass transition temperature of 100 ° C. or higher is 1% by mass or less in total. ), [2] the step of producing an acrylic pressure-sensitive adhesive by mixing the acrylic polymer (a1) and a crosslinking agent, and the acrylic pressure-sensitive adhesive at least one of the light-shielding substrates. The process of manufacturing the adhesive layer (A) whose tensile strength based on the stress-strain curve in 100% of strain amount is 6 N / cm < ² > or more by applying to the surface side [ 3].

Moreover, as a more suitable manufacturing method of the light-shielding pressure-sensitive adhesive tape of the present invention, for example, the total content of vinyl monomers other than (meth) acrylic monomers with respect to the total amount of vinyl monomer components is 5% by mass or less, and An acrylic polymer having a weight average molecular weight of 1,000,000 to 3,000,000 by polymerizing a vinyl monomer mixture having a total content of alkyl (meth) acrylate having a glass transition temperature of 100 ° C. or higher of the homopolymer of 1% by mass or less. Step [1] for producing (a1), Step [2] for producing an acrylic pressure-sensitive adhesive by mixing the acrylic polymer (a1) and a crosslinking agent, and coating the acrylic pressure-sensitive adhesive on the surface of the release liner. A step [4] of producing a pressure-sensitive adhesive layer (A) having a tensile strength of 6 N / cm ² or more based on a stress-strain curve at a strain amount of 100% by processing; and The method which has the process [5] which transfers the said adhesive layer (A) to the at least one surface side of the said light-shielding base material is mentioned.

  The total thickness of the light-shielding pressure-sensitive adhesive tape obtained by the above method is preferably 20 μm to 100 μm, preferably 25 μm to 85 μm, and preferably 25 μm to 60 μm with good workability and good It is preferable for obtaining a light-shielding pressure-sensitive adhesive tape having a sufficient static load holding force.

  The light-shielding pressure-sensitive adhesive tape of the present invention has even more excellent peel adhesion and static load retention. Moreover, the light-shielding adhesive tape of this invention can be equipped with the outstanding impact resistance by using the said specific foam base material, without reducing the outstanding peel adhesive force and a static load holding power. Therefore, the light-shielding pressure-sensitive adhesive tape of the present invention has a width of the narrowest portion of the light-shielding pressure-sensitive adhesive tape of 5 mm or less, preferably 0.1 mm to 3 mm, more preferably 0.5 mm to 2. It can be used for fixing a member limited to 5 mm.

  The narrow member is often used as a member in industrial applications such as portable electronic devices such as mobile phones, automobiles, building materials, OA, and home appliance industries.

  Specific examples of the member include two or more casings and lens members that constitute an electronic terminal.

As a usage form of the light-shielding adhesive tape of the present invention, an optical film is provided on the outermost layer of the backlight casing, and the optical film and the LCD panel are integrated via the light-shielding adhesive tape. There is a configuration in which the LCD panel is integrated with another structure laminated on the optical film, which is integrated with the backlight housing via a light-shielding adhesive tape.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples.

[Preparation Example 1] Production method of acrylic polymer (A-1) In a reaction vessel equipped with a stirrer, a reflux condenser, a nitrogen inlet tube, and a thermometer, 75.94 parts by mass of n-butyl acrylate, 2-ethylhexyl acrylate 5 Part by mass, 15 parts by mass of cyclohexyl acrylate, 4 parts by mass of acrylic acid, 0.06 part by mass of 4-hydroxybutyl acrylate, and 200 parts by mass of ethyl acetate were added, and the temperature was raised to 65 ° C. while blowing nitrogen under stirring. .

  Next, 4 parts by mass of a 2,2′-azobisisobutyronitrile solution (solid content: 2.5% by mass) previously dissolved in ethyl acetate is added to the mixture, and the mixture is held at 65 ° C. for 10 hours with stirring. did.

  Next, the mixture was diluted with 98 parts by mass of ethyl acetate and filtered through a 200 mesh wire netting to obtain an acrylic polymer (A-1) solution (nonvolatile content: 33% by mass) having a weight average molecular weight of 1,600,000.

In addition, the said weight average molecular weight is a weight average molecular weight in standard polystyrene conversion measured by a gel permeation chromatograph (GPC), and was measured with the following method.
The measurement of the molecular weight by GPC method is a standard polystyrene conversion value measured using a GPC apparatus (HLC-8329GPC) manufactured by Tosoh Corporation.

Sample concentration: 0.5% by mass (tetrahydrofuran solution)
Sample injection volume: 100 μl
Eluent: THF (tetrahydrofuran)
Flow rate: 1.0 ml / min Measurement temperature: 40 ° C
This column: TSKgel GMHHR-H (20) 2 Guard column: TSKgel HXL-H
Detector: differential refractometer Standard polystyrene molecular weight: 10,000 to 20 million (manufactured by Tosoh Corporation)

[Preparation Example 2]
The amount of n-butyl acrylate used was changed from 75.94 parts by mass to 56.94 parts by mass, the amount of 2-ethylhexyl acrylate used was changed from 5 parts by mass to 40 parts by mass, and the amount of acrylic acid used was 4 The acrylic polymer (A-) having a weight average molecular weight of 13.3 million was changed in the same manner as in Preparation Example 1 except that the amount of cyclohexyl acrylate was changed from 10 parts by weight to 0 parts by weight. 2) A solution (nonvolatile content 33% by mass) was obtained.

[Comparative Preparation Example 1] Production method of acrylic polymer (B-1) In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube, and thermometer, 92.8 parts by mass of n-butyl acrylate, 2 parts by mass of acrylic acid Parts, 5 parts by mass of vinyl acetate, 0.2 parts by mass of hydroxyethyl acrylate, and 100 parts by mass of ethyl acetate were added and the temperature was raised to 80 ° C. while blowing nitrogen under stirring.

  Next, 4 parts by mass of a 2,2′-azobisisobutyronitrile solution (solid content: 2.5% by mass) previously dissolved in ethyl acetate was added to the mixture, and the mixture was held at 72 ° C. for 8 hours with stirring. did.

  Next, the mixture was diluted with 66 parts by mass of ethyl acetate and filtered through a 200 mesh wire mesh to obtain an acrylic polymer (B-1) solution (non-volatile content: 37% by mass) having a weight average molecular weight of 800,000.

[Comparative Adjustment Example 2] Method for Producing Acrylic Polymer (B-2) In a reaction vessel equipped with a stirrer, reflux condenser, nitrogen inlet tube and thermometer, 93 parts by mass of n-butyl acrylate and 3.5 parts by mass of acrylic acid Part, 3.4 parts by weight of vinyl acetate, 0.1 part by weight of hydroxyethyl acrylate, and 100 parts by weight of ethyl acetate were added, and the temperature was raised to 72 ° C. while blowing nitrogen under stirring.

  Next, 0.2 parts by mass of a 2,2′-azobisisobutyronitrile solution previously dissolved in ethyl acetate (solid content: 0.1% by mass) was added to the mixture, and the mixture was stirred at 72 ° C. for 8 parts. Hold time.

  Next, the mixture was diluted with 98 parts by mass of ethyl acetate and filtered through a 200 mesh wire mesh to obtain an acrylic polymer (B-2) solution having a weight average molecular weight of 800,000.

[Example 1]
In a container, 5 parts by mass of polymerized rosin ester-based tackifier resin D-125 (Arakawa Chemical Co., Ltd.) and petroleum-based tackifier resin FTR6125 (Mitsui Chemicals) with respect to 100 parts by mass of the acrylic polymer (A-1). (Company) 15 parts by mass was mixed and stirred, and then ethyl acetate was added to obtain an adhesive solution having a solid content of 31% by mass.

  Next, Vernock D-40 (manufactured by DIC Corporation, trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, nonvolatile content 40% by mass with respect to 100 parts by mass of the pressure-sensitive adhesive solution. ) After adding 0.8 parts by mass, stirring and mixing so as to be uniform, an adhesive (p-1) was obtained by filtering through a 100 mesh wire net.

  Next, the pressure-sensitive adhesive is coated on the surface of the release liner using a bar coater so that the thickness of the pressure-sensitive adhesive layer after drying is 16 μm, and dried at 85 ° C. for 2 minutes. A layer was made.

Next, the pressure-sensitive adhesive layer was coated with a light-shielding substrate (a light-shielding substrate having a total thickness of 18 μm having a black ink layer (light-shielding layer) having a thickness of 3 μm on both sides of a PET film having a thickness of 12 μm, a light transmittance of 0.1 μm). 09 cd / m ² ) and cured for 48 hours in an environment of 40 ° C. to produce a light-shielding adhesive tape (P-1). The light transmittance is 10,000 cd / m ^{2 on} a light box (manufactured by Dentsu Sangyo Co., Ltd.), and the light-shielding base material is placed on a light meter (I-System Co., Ltd.). It is a value obtained by measuring by (made).

[Example 2]
A pressure-sensitive adhesive (p-2) and a light-shielding pressure-sensitive adhesive tape (P-2) in the same manner as in Example 1 except that the blending amount of Bernock D-40 was changed from 0.8 parts by mass to 1.0 part by mass. Got.

[Example 3]
Adhesive (p-3) and light-shielding adhesive tape (P-3) in the same manner as in Example 1 except that the amount of Vernock D-40 was changed from 0.8 parts by mass to 1.3 parts by mass Got.

[Example 4]
For the tackifier resin, 15 parts by mass of petroleum-based tackifier resin FTR6125 (manufactured by Mitsui Chemicals) is changed to 4 parts by mass of polymerized rosin ester-based tackifier resin D160 (Arakawa Chemical Industries, Ltd.). A pressure-sensitive adhesive (p-4) and a light-shielding pressure-sensitive adhesive tape (P-4) were obtained in the same manner as in Example 1 except that the blending amount was changed from 0.8 parts by mass to 1.0 part by mass.

[Example 5]
Instead of the acrylic polymer (A-1) solution, the pressure-sensitive adhesive (p-5) and pressure-sensitive adhesive sheet (p-5) and pressure-sensitive adhesive sheet (in the same manner as in Example 1) except that the acrylic polymer (A-2) solution was used. P-5) was obtained.

[Comparative Example 1]
In a container, with respect to 100 parts by mass of the acrylic polymer (B-1), 20 parts by mass of polymerized rosin ester-based tackifier resin Superester A100 (Arakawa Chemical Co., Ltd.) and petroleum-based tackifier resin FTR6100 (Mitsui Chemicals, Inc.) (Made by company) 20 parts by mass was mixed and stirred, and then ethyl acetate was added to obtain a pressure-sensitive adhesive solution having a solid content of 40% by mass.

  Next, Vernock D-40 (manufactured by DIC Corporation, trimethylolpropane adduct of tolylene diisocyanate, isocyanate group content 7% by mass, nonvolatile content 40% by mass with respect to 100 parts by mass of the pressure-sensitive adhesive solution. ) 1.5 parts by mass was added, and the mixture was stirred and mixed to be uniform, and then filtered through a 100 mesh wire net to obtain an adhesive (q-1).

  Next, the pressure-sensitive adhesive is applied to the surface of the release liner using a bar coater so that the thickness of the pressure-sensitive adhesive layer after drying is 16 μm, and dried at 85 ° C. for 2 minutes. A layer was made.

  Next, the pressure-sensitive adhesive layer is applied to both sides of a light-shielding substrate (a light-shielding substrate having a total thickness of 18 μm having a black ink layer (light-shielding layer) having a thickness of 3 μm on both sides of a PET film having a thickness of 12 μm). The light-shielding adhesive tape (Q-1) was produced by curing for 48 hours in an environment of 40 ° C.

[Comparative Example 2]
A pressure-sensitive adhesive (q-2) and a light-shielding pressure-sensitive adhesive tape (Q-2) in the same manner as in Example 1 except that the blending amount of Bernock D-40 is changed from 1.5 parts by mass to 1.1 parts by mass. Got.

[Comparative Example 3]
A pressure-sensitive adhesive (q-3) and a light-shielding pressure-sensitive adhesive tape (Q-3) in the same manner as in Example 1 except that the blending amount of Bernock D-40 was changed from 1.5 parts by mass to 0.7 parts by mass. Got.

[Comparative Example 4]
Instead of the acrylic polymer (B-1) solution, the acrylic polymer (B-2) solution is used, and the amount of Bernock D-40 is changed from 1.5 parts by mass to 1.24 parts by mass. Except for this, a pressure-sensitive adhesive (q-4) and a pressure-sensitive adhesive sheet (Q-4) were obtained in the same manner as in Example 1.

[Measurement Method of Tensile Strength Based on Stress-Strain Curve at 100% and 500% Strain]
The pressure-sensitive adhesive was applied to one side of an arbitrary release liner, dried at 80 ° C. for 3 minutes, and aged at 40 ° C. for 48 hours to form a pressure-sensitive adhesive layer having a thickness of 50 μm. Next, this pressure-sensitive adhesive layer was laminated to a thickness of about 400 μm to prepare a test piece having a marked line interval of 2 cm and a width of 1 cm.

  From the stress-strain curve (so-called SS curve) measured at a tensile speed of 300 mm / min using a tensile tester in a measurement environment at a temperature of 23 ° C. and a relative humidity of 50%, the amount of strain was measured. Obtained the tensile strength at 100% and 500%.

[Measurement method of gel fraction of adhesive layer]
The pressure-sensitive adhesive composition is applied to one side of an arbitrary release liner, dried at 100 ° C. for 3 minutes, and aged at 40 ° C. for 2 days to form a pressure-sensitive adhesive layer having a thickness of 50 μm and cut into a 50 mm square. Samples were used as samples.

  Next, after measuring the mass (G1) of the sample, the sample was immersed in a toluene solution at 23 ° C. for 24 hours. The toluene-insoluble matter of the sample after the immersion is separated by filtering through a 300 mesh wire mesh, and the mass (G2) of the residue after drying at 110 ° C. for 1 hour is measured, and the gel fraction is obtained according to the following formula. It was.

    Gel fraction (mass%) = (G2 / G1) × 100

[Measurement method of 180 ° peel adhesive strength]
Under the environment of a temperature of 23 ° C. and a relative humidity of 50% RH, the adhesive layer surface on one side of the light-shielding adhesive tape prepared in Examples and Comparative Examples was lined with a PET film having a thickness of 25 μm, and then a length of 120 mm and a width of Cut to 20 mm.

  Next, the surface of the pressure-sensitive adhesive layer on the other side is attached to a stainless steel plate, and the upper surface of the PET film is reciprocated once using a 2 kg roller. Further, they are placed in an environment at a temperature of 23 ° C. and a relative humidity of 50% RH. The test piece 1 in which the PET film, the light-shielding pressure-sensitive adhesive tape, and the stainless steel plate were bonded to each other was prepared by allowing to stand for 1 hour.

  Next, using a Tensilon peel tester, the strength when the light-shielding adhesive tape is peeled off in the 180 ° direction at a tensile speed of 300 mm / min with the stainless steel plate constituting the test piece 1 fixed is measured. did.

[Evaluation method of static load holding force]
One pressure-sensitive adhesive layer of a frame-shaped light-shielding pressure-sensitive adhesive tape having an outer shape of 14 mm × 14 mm and a light-shielding pressure-sensitive adhesive tape width of 2 mm under an atmosphere of a temperature of 23 ° C. and a relative humidity of 50% is smooth on the surface of 1 mm in thickness and 50 mm × 50 mm in outer diameter. Affixed to a glass plate.

Next, a polycarbonate plate having a diameter of 8 mm in the center and a thickness of 4 mm and an outer shape of 50 mm × 50 mm and the other adhesive layer of the glass plate with the light-shielding adhesive tape were pasted so as to close the hole. After that, a test piece 2 was pressure-bonded at 50 N / cm ² for 10 seconds.

  In an atmosphere at a temperature of 80 ° C. and a relative humidity of 10%, the test piece 2 was fixed horizontally at a position of 10 cm in height so that the glass plate side was down. Next, a 200 g weight was placed in the hole of the test piece 2, and the glass plate with the light-shielding adhesive tape was left in a state of being weighted downward.

  The time (minute) until the distance between the glass plate with the light-shielding pressure-sensitive adhesive tape and the polycarbonate plate was 0.2 mm away from the time before starting to stand was measured.

[Prism sheet test]
One pressure-sensitive adhesive layer of a frame-shaped light-shielding pressure-sensitive adhesive tape having an outer diameter of 107 mm × 142 mm and a light-shielding pressure-sensitive adhesive tape width of 2 mm in an atmosphere of a temperature of 23 ° C. and a relative humidity of 50% has a smooth surface with a thickness of 2 mm and an outer diameter of 120 mm × 160 mm Affixed to a glass plate.

  Next, the prism surface of the prism sheet is affixed to the other side of the light-shielding adhesive tape, and the top surface of the prism sheet is reciprocated once using a 2 kg roller. The specimen 3 was prepared by allowing the prism sheet, the light-shielding adhesive tape, and the glass plate to adhere to each other.

Next, the test piece 3 was allowed to stand in an atmosphere at a temperature of 85 ° C. for 240 hours, and then allowed to stand in an atmosphere at 23 ° C. for 1 hour. It was visually evaluated whether there was a change in the appearance of the prism sheet before and after standing in an atmosphere of 85 ° C.
A: No distortion occurred in the prism sheet.
○: Slight distortion occurred in the prism sheet, but it was at a level where there was no practical problem.
Δ: The prism sheet was distorted.
X: Large distortion occurred in the prism sheet.

[Light shielding (light transmittance)]
A light-shielding adhesive tape is placed on a light box (made by Dentsu Sangyo Co., Ltd.) with a light shielding property (light transmittance) of 10000 cd / m ² , and the light transmitted through the light-shielding adhesive tape is measured by a luminance meter (I-System Co., Ltd.). Manufactured).

Claims (9)

A light-shielding pressure-sensitive adhesive tape comprising a pressure-sensitive adhesive layer (A) having a tensile strength of 6 N / cm ² or more based on a stress-strain curve at a strain amount of 100% on at least one surface side of a light-shielding substrate. The light-shielding pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive layer (A) is a pressure-sensitive adhesive layer using an acrylic polymer (a1) having a weight average molecular weight of 1,000,000 to 3,000,000 and a crosslinking agent. The light-shielding pressure-sensitive adhesive tape according to claim 1 or 2, wherein the pressure-sensitive adhesive layer (A) has a gel fraction of 20% by mass to 50% by mass. The light shielding substrate, the light-shielding pressure-sensitive adhesive tape according to any one of claims 1 to 3 the light transmission amount of when irradiated with light of 10000 cd / ^{m 2} is of 10 cd / ^{m 2} or less. The light-shielding pressure-sensitive adhesive tape according to claim 1, wherein the light-shielding substrate has a thickness of 20 μm or less. The light shielding adhesive tape according to claim 5, wherein the light shielding substrate has a light shielding layer on at least one surface side of the polyester film. The content of vinyl monomers other than (meth) acrylic monomers with respect to the total amount of vinyl monomer components is 5% by mass or less, and the glass transition temperature of the homopolymer is 100 ° C. or higher. Step [1] of producing an acrylic polymer (a1) having a weight average molecular weight of 1,000,000 to 3,000,000 by polymerizing a vinyl monomer mixture having a total content of 1% by mass or less, the acrylic polymer (a1) [2] for producing an acrylic pressure-sensitive adhesive by mixing a cross-linking agent and stress-strain at a strain amount of 100% by applying the acrylic pressure-sensitive adhesive to at least one surface side of the light-shielding substrate A method for producing a light-shielding pressure-sensitive adhesive tape, comprising a step [3] of producing a pressure-sensitive adhesive layer (A) having a tensile strength based on a curve of 6 N / cm ² or more. The content of vinyl monomers other than (meth) acrylic monomers with respect to the total amount of vinyl monomer components is 5% by mass or less, and the glass transition temperature of the homopolymer is 100 ° C. or higher. Step [1] of producing an acrylic polymer (a1) having a weight average molecular weight of 1,000,000 to 3,000,000 by polymerizing a vinyl monomer mixture having a total content of 1% by mass or less, the acrylic polymer (a1) Step [2] of producing an acrylic pressure-sensitive adhesive by mixing a crosslinking agent and a tensile strength based on a stress-strain curve at a strain amount of 100% by applying the acrylic pressure-sensitive adhesive to the surface of the release liner [4] for producing a pressure-sensitive adhesive layer (A) having a N of 6 N / cm ² or more, and transferring the pressure-sensitive adhesive layer (A) to at least one surface side of the light-shielding substrate. A method for producing a light-shielding pressure-sensitive adhesive tape comprising the step [5]. The liquid crystal display device which has the structure by which the housing | casing provided with the backlight and the liquid crystal display panel were fixed by the light-shielding adhesive tape of any one of Claims 1-6.

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