JP2017014461A - Acrylic adhesive composition for light-shielding double-sided adhesive member, light-shielding double-sided adhesive member and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acrylic adhesive composition for a light-shielding double-sided adhesive member that hardly causes peeling-off from an adherend surface comprising a resin and has excellent workability when adhered.SOLUTION: An acrylic adhesive composition for a light-shielding double-sided adhesive member includes an acrylic polymer produced by copolymerizing a monomer mixture containing 10 to 30 wt% of an acrylic monomer having a glass transition temperature of 0°C to 80°C when constituting a homopolymer and having no crosslinkable functional group and 2 to 7 wt% of a monomer containing a carboxyl group, where the acrylic polymer has a weight average molecular weight of 750,000 to 1,250,000. A light-shielding double-sided adhesive member using the acrylic adhesive composition for a light-shielding double-sided adhesive member and an image display device using the light-shielding double-sided adhesive member are provided.SELECTED DRAWING: None

Description

  The present invention relates to an acrylic pressure-sensitive adhesive composition for a light-shielding double-sided pressure-sensitive adhesive member, a light-shielding double-sided pressure-sensitive adhesive member, and an image display device.

  In a non-self-luminous display device such as a liquid crystal display device, a non-self-luminous display unit such as a liquid crystal display module unit and a backlight unit are attached by a double-sided adhesive member such as a double-sided adhesive tape having at least a light shielding function. Is done. For example, as a double-sided pressure-sensitive adhesive member used for adhering to a liquid crystal display module unit and a backlight unit, Patent Document 1 discloses a glass transition temperature of 60) when a) an acrylic polymer and b) a homopolymer are formed. Acrylic pressure-sensitive adhesive comprising a low molecular weight polymer component having a weight average molecular weight of 3,000 to less than 20,000 based on an ethylenically unsaturated monomer monomer having a cyclic structure in the molecule at ˜190 ° C. A double-sided pressure-sensitive adhesive member provided with a pressure-sensitive adhesive layer formed of an adhesive composition has been proposed.

JP 2007-254711 A

  On the other hand, when the non-self-luminous display unit is a display unit that is driven and controlled by a circuit board such as a liquid crystal module unit, the display unit and the backlight unit are connected via an FPC (Flexible printed circuits). Sometimes. When connecting both units via the FPC, the FPC normally connects both units in a bent state, and therefore, a repulsive force caused by the bent FPC acts between the two units. Therefore, such a repulsive force acts strongly as a force for peeling off the sticking interface between the unit and the double-sided pressure-sensitive adhesive member.

  Further, when a polycarbonate substrate is used as the resin substrate constituting the backlight unit, outgas (gas caused by moisture, residual monomer, etc.) is likely to be generated from the polycarbonate material in a high temperature environment. For this reason, foaming may be caused in the pressure-sensitive adhesive layer constituting the double-sided pressure-sensitive adhesive member to be adhered to the adherend surface (polycarbonate substrate) of the backlight, which may cause device failure and display quality deterioration. Therefore, when the repulsive force due to the FPC described above is further applied and the condition that the display device is exposed to a high temperature environment overlaps, the peeling particularly occurs at the bonding interface between the backlight unit and the double-sided adhesive member. Is likely to occur.

  On the other hand, when sticking units together using a double-sided adhesive member, the double-sided adhesive member is cut into a desired shape or length, or the double-sided adhesive member is adhered and fixed to the surface of the unit. Work is required. Therefore, the double-sided pressure-sensitive adhesive member is also required to have such characteristics that these sticking operations can be performed easily and reliably.

  The present invention has been made in view of the above circumstances, and is an acrylic system for a light-shielding double-sided pressure-sensitive adhesive member that hardly peels off from a resin-coated surface and has excellent workability at the time of sticking. It is an object of the present invention to provide a light-blocking double-sided pressure-sensitive adhesive member using a pressure-sensitive adhesive composition, an acrylic pressure-sensitive adhesive composition for light-blocking double-sided pressure-sensitive adhesive members, and an image display device using the light-blocking double-sided pressure-sensitive adhesive member.

The above-mentioned subject is achieved by the following present invention. That is,
The acrylic pressure-sensitive adhesive composition for a light-shielding double-sided pressure-sensitive adhesive member of the present invention has an acrylic monomer having a glass transition temperature of 0 ° C. to 80 ° C. when a homopolymer is formed and having no crosslinkable functional group The acrylic polymer obtained by copolymerizing a monomer mixture containing 10 to 30% by weight and 2 to 7% by weight of a monomer containing a carboxyl group, and the acrylic polymer has a weight average molecular weight of 750,000 to It is characterized by being 1.25 million.

  One embodiment of the acrylic pressure-sensitive adhesive composition for a light-shielding double-sided pressure-sensitive adhesive member of the present invention is preferably used for sticking to a member whose adherend surface is made of a polycarbonate resin.

  It is preferable that other embodiment of the acrylic adhesive composition for light-shielding double-sided adhesive members of this invention further contains rosin ester resin.

  The light-shielding double-sided pressure-sensitive adhesive member of the present invention includes a film-like base material, a pressure-sensitive adhesive layer provided on at least one side of the base material, and comprising the acrylic pressure-sensitive adhesive composition for the light-shielding double-sided pressure-sensitive adhesive member of the present invention, And at least.

  The image display device of the present invention comprises at least a non-self-luminous display unit, a backlight unit, and the light-shielding double-sided adhesive member of the present invention disposed between the non-self-luminous display unit and the backlight unit. It is characterized by providing.

  In one embodiment of the image display device of the present invention, the non-self-luminous display unit is preferably a liquid crystal display module unit.

  In another embodiment of the image display device of the present invention, it is preferable that the surface of the backlight unit that contacts the light-shielding double-sided pressure-sensitive adhesive member is made of a polycarbonate resin.

  According to the present invention, an acrylic pressure-sensitive adhesive composition for a light-shielding double-sided pressure-sensitive adhesive member, which is unlikely to peel off from an adherend surface made of a resin and excellent in workability at the time of sticking, and a light-shielding double-sided pressure-sensitive adhesive member A light-shielding double-sided pressure-sensitive adhesive member using the acrylic pressure-sensitive adhesive composition for use, and an image display device using the light-shielding double-sided pressure-sensitive adhesive member can be provided.

It is a schematic cross section which shows an example of the layer structure of the adhesion member of this embodiment. It is a schematic cross section which shows the other example of the layer structure of the adhesion member of this embodiment. It is a schematic cross section which shows the other example of the layer structure of the adhesion member of this embodiment. It is a schematic cross section which shows the other example of the layer structure of the adhesion member of this embodiment.

  The acrylic pressure-sensitive adhesive composition for light-shielding double-sided pressure-sensitive adhesive members of the present embodiment (hereinafter sometimes simply referred to as “pressure-sensitive adhesive composition”) has a glass transition temperature of 0 ° C. to 80 ° C. when a homopolymer is formed. And obtained by copolymerizing a monomer mixture containing 10 to 30% by weight of an acrylic monomer having no crosslinkable functional group and 2 to 7% by weight of a monomer containing a carboxyl group. An acrylic polymer is included, and the acrylic polymer has a weight average molecular weight of 750,000 to 12,500.

  The pressure-sensitive adhesive composition of this embodiment contains an acrylic polymer as a main component. The weight average molecular weight of this acrylic polymer measured by GPC (Gel Permeation Chromatography) method is 750,000 to 12,500, preferably 800,000 to 1,200,000, and more preferably 900,000 to 1,000,000. When the weight average molecular weight is less than 750,000, in the light-shielding double-sided pressure-sensitive adhesive member provided with the pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition of the present embodiment, the pressure-sensitive adhesive layer tends to be excessively sticky. For this reason, it is difficult to cut the light-shielding double-sided pressure-sensitive adhesive member into a desired shape or length. On the other hand, when the weight average molecular weight exceeds 1.25 million, the pressure-sensitive adhesive layer becomes too hard, so that tackiness is greatly reduced. That is, when the weight average molecular weight is outside the range of 750,000 to 12,500, workability at the time of cutting and sticking of the light-shielding double-sided pressure-sensitive adhesive member decreases.

  The acrylic monomer (a) used for copolymerization of the acrylic polymer does not have a crosslinkable functional group, and has a glass transition temperature of 0 ° C. to 80 ° C. when forming a homopolymer. . By setting the glass transition temperature to 0 ° C. or higher, it is difficult for peeling to the adherend surface made of resin, and in particular, peeling is also caused to the adherend surface made of polycarbonate resin that easily generates outgas in a high temperature environment. It becomes difficult. Moreover, since it can prevent that tackiness falls because an adhesive layer becomes hard too much by making glass transition temperature into 80 degrees C or less, it can avoid that workability | operativity at the time of sticking falls. The glass transition temperature is preferably 0 ° C to 50 ° C, more preferably 0 ° C to 30 ° C. In the present specification, examples of the “crosslinkable functional group” include a carboxyl group, a hydroxyl group, an amino group, an amide group, a cyano group, and a thiol group.

  As the above-mentioned (a) acrylic monomer, methyl acrylate can be preferably used. In addition, an alkyl (meth) acrylate monomer having an alkyl group having 1 to 7 carbon atoms, a cycloalkyl (meth) acrylate monomer having a cycloalkyl group having 3 to 7 carbon atoms, and an aralkyl group having 7 to 9 carbon atoms. Among the aralkyl (meth) acrylate monomers having, monomers having a glass transition temperature in the range of 0 ° C. to 80 ° C. are also included. Specific examples of these acrylate monomers include, in addition to the above-mentioned methyl acrylate, isobutyl methacrylate, tetrahydrofurfuryl methacrylate, n-butyl methacrylate, cyclohexyl acrylate, benzyl acrylate, and the like.

  On the other hand, as the monomer (b) containing a carboxyl group used for copolymerization of an acrylic polymer, any monomer containing a carboxyl group in the molecule can be used without particular limitation. It is particularly preferable to use acrylic acid.

  The acrylic polymer is obtained by copolymerizing a monomer mixture containing (a) 10 to 30% by weight of an acrylic monomer and (b) 2 to 7% by weight of a monomer containing a carboxyl group. By using a combination of (a) an acrylic monomer and (b) a monomer containing a carboxyl group, the acrylic polymer can function as an adhesive.

  In addition, (a) by setting the blending ratio of the acrylic monomer to 10% by weight or more, peeling to the adherend surface made of the resin is less likely to occur, and in particular, it is made of a polycarbonate resin that easily generates outgas in a high temperature environment. Peeling is less likely to occur on the wearing surface. Moreover, (a) By making the mixing | blending ratio of an acryl-type monomer 30 weight% or less, it can have moderate tackiness, without making the adhesive layer obtained hard. Furthermore, (b) By making the mixture ratio of the monomer containing a carboxyl group 2% by weight or more, it is possible to impart appropriate cohesiveness to the obtained pressure-sensitive adhesive layer and to have good constant load peeling resistance. . Moreover, the tackiness suitable for a sticking operation | work can be acquired by the mixture ratio of the monomer containing (b) carboxyl group being 7 weight% or less. In addition, the blending ratio of the (a) acrylic monomer is preferably 10 to 25% by weight, and the blending ratio of the monomer (b) containing a carboxyl group is preferably 3 to 6% by weight.

  In addition, (c) other monomers other than the above (a) acrylic monomer and (b) a monomer containing a carboxyl group are used in the copolymerization of the acrylic polymer, and (c) other monomer in the monomer mixture. The blending ratio of (a) is the remaining amount excluding the blending amount of the acrylic monomer and (b) the blending amount of the monomer containing a carboxyl group, that is, 63 to 88% by weight. (C) Other monomers include known monomers used for copolymerization of adhesive polymers (except for those corresponding to (a) acrylic monomers and (b) carboxyl group-containing monomers). Can be suitably selected from, for example, 2-ethylhexyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, 4-hydroxybutyl acrylate, acrylamide, and the like.

  Further, as the other monomer (c), it is also preferable to use a small amount of a high molecular weight monomer (macromonomer) having a polymerizable functional group in addition to the above-described general low molecular weight monomer. As such a macromonomer, the terminal functional group has a methacryloyl group and / or a dihydroxyl group, the segment has methyl methacrylate, styrene-acrylonitrile, butyl acrylate or the like, and the number average molecular weight is about 3000 to 10,000. These monomers are mentioned. In addition, when using a macromonomer, about 0.5 to 5 weight% is preferable as the mixture ratio in a monomer mixture.

  In addition, the adhesive composition of this embodiment may contain other components as needed in addition to the acrylic polymer. In this case, as other components, it is preferable to use a rosin ester resin as a tackifier resin, and it is more preferable to use a polymerized rosin ester resin. By using a rosin ester resin in addition to an acrylic polymer as a component constituting the pressure-sensitive adhesive composition, for example, an olefin-based adherend such as polyethylene and polypropylene, which is generally a hardly adherent adherend for acrylic pressure-sensitive adhesives. Can exhibit good adhesiveness (adhesiveness), and can improve the constant load peel resistance of the resulting pressure-sensitive adhesive layer. When the rosin ester resin is used as the other component, the blending amount of the rosin ester resin with respect to 100 parts by weight of the acrylic polymer is more than 0 parts by weight, preferably 35 parts by weight, more preferably 5 to 25 parts by weight, and 15 to 25 parts by weight. Part is more preferable.

  Moreover, since the adhesive composition of this embodiment is used for the adhesive layer which comprises the light-shielding double-sided adhesive member which has a light-shielding function at least, it has light-shielding properties, such as a black color material, as another component. The substance may be contained in an appropriate amount as long as the function of the pressure-sensitive adhesive layer is not impaired. Further, when the light-shielding double-sided pressure-sensitive adhesive member further has a reflection function in addition to the light-shielding function, a reflective material such as a white color material or a silver color material as the other component functions as a pressure-sensitive adhesive layer. It may be contained in an appropriate amount as long as it does not inhibit.

  Although the adhesive composition of this embodiment demonstrated above can be utilized for the sticking to various solid surfaces, it is used for the sticking to the members (resin substrate etc.) which a to-be-coated surface consists of resin. Particularly, it is particularly preferable to use for adhesion to a member (a polycarbonate substrate or the like) whose surface to be adhered is made of a polycarbonate resin.

  Next, the light-shielding double-sided pressure-sensitive adhesive member using the pressure-sensitive adhesive composition of the present embodiment will be described below. The light-shielding double-sided pressure-sensitive adhesive member of the present embodiment (hereinafter sometimes simply referred to as “adhesive member”) includes at least a film-like substrate and a pressure-sensitive adhesive layer containing the pressure-sensitive adhesive composition of the present embodiment. Prepare. Further, in the pressure-sensitive adhesive member of the present embodiment, the pressure-sensitive adhesive layer is provided on both surfaces of the base material. Of these two pressure-sensitive adhesive layers, at least one pressure-sensitive adhesive layer contains the pressure-sensitive adhesive composition of the present embodiment. It only has to be. However, it is usually particularly preferable that the pressure-sensitive adhesive composition of the present embodiment is contained in the pressure-sensitive adhesive layers respectively provided on both sides of the base material from the viewpoint of allowing the pressure-sensitive adhesive member to be used without distinction between the front and back sides. .

  Moreover, the adhesive member of this embodiment is provided with at least a light blocking function that blocks transmission of light from one surface side to the other surface side and in the opposite direction. This light shielding function may be exhibited only by the base material, or may be exhibited only by the pressure-sensitive adhesive layer provided on both sides or one side of the base. The base and the both sides or one side of the base It may be demonstrated by the combination with the adhesive layer provided in the. Furthermore, the pressure-sensitive adhesive member of this embodiment may have a reflection function of reflecting light incident from one surface side in addition to the light shielding function. This reflection function may be exhibited only by the base material, or may be exhibited only by the pressure-sensitive adhesive layer provided only on one surface side of the base material, and only the base material and one surface side of the base material. It may be exhibited by a combination with the pressure-sensitive adhesive layer provided on the surface.

  The layer structure of the substrate is not particularly limited, and may be a single layer structure or a multilayer structure of two or more layers. The thickness of the substrate is not particularly limited, but can be appropriately selected from a range of 1 to 3000 μm, for example. As the base material, at least a film-like member such as a film made of a fibrous substance such as a resin film, a metal film, and pulp fiber is used, and a printing layer is provided on one or both sides of the film-like member as necessary. A metal layer or the like can be provided as appropriate.

  Here, it is particularly preferable to use a resin film as the film-like member. As the resin film, a known resin film such as a polyethylene terephthalate film (PET film), a polyethylene film, or a polypropylene film can be appropriately used. In addition, a normal resin film does not have sufficient light-shielding property and reflectivity. For this reason, when imparting light-shielding properties to the resin film itself, a black color material such as a black pigment is dispersed in the resin film matrix, and when imparting reflectivity to the resin film itself, In addition, a white color material such as a white pigment or a silver color material such as a silver pigment may be dispersed and contained. In addition, when providing light-shielding property and reflectivity simultaneously to resin film itself, the resin film which has light-shielding property, and the resin film which has reflectivity can be laminated | stacked and used.

  As the color material used for imparting light-shielding properties and reflectivity, known pigments and dyes can be used as appropriate, and specific examples thereof include the color materials exemplified below. First, as black color materials, for example, carbon black, graphite, copper oxide, manganese dioxide, aniline black, perylene black, titanium black, cyanine black, activated carbon, ferrite, magnetite, chromium oxide, molybdenum disulfide, composite oxide And black anthraquinone organic black pigments. These black color materials can be used alone or in combination of two or more. In addition, in order to obtain the same light shielding property as that of the black color material, a mixture obtained by mixing three color materials of cyan, magenta, and yellow using a subtractive color mixture instead of the black color material. Color materials can also be used.

  Examples of white color materials include titanium oxide, zinc oxide, aluminum oxide, silicon oxide, zirconium oxide, magnesium oxide, calcium oxide, tin oxide, barium oxide, cesium oxide, yttrium oxide, magnesium carbonate, calcium carbonate, and barium carbonate. , Zinc carbonate, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide, aluminum silicate, magnesium silicate, calcium silicate, barium sulfate, calcium sulfate, barium stearate, zinc white, zinc sulfide, talc, silica, alumina , Clay, kaolin, titanium phosphate, mica, gypsum, white carbon, diatomaceous earth, bentonite, lithopone, zeolite, sericite, hydrous halloysite, inorganic white color materials, acrylic resin particles, polystyrene resin particles Polyurethane resin particles, amide resin particles, polycarbonate resin particles, silicone resin particles, urea - formalin resin particles, and the like white colorant organic melamine resin particles. A fluorescent whitening agent can also be used as the white colorant, and the fluorescent whitening agent can be appropriately selected from known fluorescent whitening agents. These white color materials can be used alone or in combination of two or more.

  In addition, as a silver-based color material, for example, the surface of a flaky metal such as silver or aluminum or a flaky glass particle is coated with a metal film or a metal oxide film to give the glitter. And a luster pigment provided with. These silver color materials can be used alone or in combination of two or more.

  Moreover, by providing a printing layer on one side or both sides of the resin film, the substrate can be provided with light-shielding properties or light-shielding properties and reflectivity. For example, a light-shielding printing layer (light-shielding layer) is formed on one surface of a resin film using an ink containing a black color material in a dispersed manner, and a white color material is formed on the other surface as necessary. Alternatively, a reflective printed layer (reflective layer) can be formed using ink containing silver color material dispersion. Moreover, you may provide the metal layer formed by vapor-depositing metals, such as aluminum, on the single side | surface or both surfaces of a resin film. For example, when a metal layer made of silver or aluminum is provided on one surface of the resin film, reflectivity can be obtained by this metal layer.

  The pressure-sensitive adhesive member of this embodiment may basically have a layer structure in which a pressure-sensitive adhesive layer, a base material, and a pressure-sensitive adhesive layer are laminated in this order, but usually covers the surfaces of the pressure-sensitive adhesive layers on both sides. A release film is further provided. However, this release film is peeled off when the adhesive member is used. As the release film, a resin film in which at least the surface in contact with the pressure-sensitive adhesive layer has peelability can be used as appropriate. Further, the thickness of each layer constituting the light-shielding double-sided pressure-sensitive adhesive member and the amount of color material used in the case of using a color material are appropriately selected so that the light-shielding property and the reflectivity further imparted as necessary can be exhibited. be able to. In order to secure sufficient light shielding properties, the transmittance of the pressure-sensitive adhesive member of this embodiment is preferably 0.5% or less, more preferably 0.3% or less, and further preferably 0.1% or less. When the light-shielding double-sided pressure-sensitive adhesive member also has reflectivity, the reflectance of the pressure-sensitive adhesive member of this embodiment is preferably 60% or more, more preferably 70% or more, and even more preferably 80% or more.

  1 to 4 are schematic cross-sectional views showing an example of the layer structure of the adhesive member of this embodiment. In the pressure-sensitive adhesive member 10A (10) shown in FIG. 1, pressure-sensitive adhesive layers 30 formed using the pressure-sensitive adhesive composition of the present embodiment are provided on both surfaces of a base material 20A (20). A release sheet 40 made of a resin film is provided so as to cover the surface of the layer 30 opposite to the side on which the base material 20A is provided. Here, 20 A of base materials consist of a resin film (light-shielding resin film) containing the black color material which functions as a light shielding layer. 2 has the same layer structure as that of the adhesive member 10A shown in FIG. 1 except that the layer structure of the base material 20 is different. Here, the base material 20B (20) shown in FIG. 2 contains a resin film (light-shielding resin film 22S (light-shielding layer)) containing a black color material and a white color material or a silver color material. It consists of the laminated body which laminated | stacked the resin film (Reflective resin film 22R (reflective layer)).

  Further, the adhesive member 10C (10) shown in FIG. 3 has the same layer structure as that of the adhesive member 10A shown in FIG. Here, the base material 20C (20) shown in FIG. 3 is a normal resin film 24T having no light-shielding property or reflectivity, and an ink containing a black color material provided on one surface of the resin film 24T. A light-shielding layer 24S composed of a printing layer formed using a resin layer and a printing layer provided on the other surface of the resin film 24T and formed using an ink containing a white color material or a silver color material, or aluminum And a reflective layer 24R made of a metal layer formed by vapor deposition of a metal such as. Moreover, the adhesive member 10D (10) shown in FIG. 4 has the same layer structure as the adhesive member 10C shown in FIG. 3 except that the layer structure of the base material 20 is different. Here, the base material 20D (20) shown in FIG. 4 uses a resin film 24T that does not have a normal light-shielding property or reflectivity, and ink that is provided on both surfaces of the resin film 24T and contains a black color material. And a light shielding layer 24S made of a printed layer.

  The shape in the planar direction of the pressure-sensitive adhesive member of the present embodiment is not particularly limited. For example, in addition to simple shapes such as a band shape (tape shape) and a square shape, the contour shape of the adherend surface of the object to be adhered It may be an annular shape having an outer peripheral shape substantially corresponding to.

  The adhesive member of the present embodiment is usually preferably used for adhering a non-self-luminous display unit, in particular, a liquid crystal display module unit and a backlight unit, but between two members to be adhered. As long as it is required to shield at least light, it can be used for applications other than those described above. Moreover, when the adhesive member of this embodiment used for sticking a non-self-luminous display unit and a backlight unit also has reflectivity as illustrated in FIGS. 2 and 3, the luminance of the backlight unit In order to further improve the above, the surface on which light is reflected is attached to the backlight unit.

  A resin substrate such as a polycarbonate substrate is usually used for the surface (attachment surface) on which the non-self-luminous display unit of the backlight unit is disposed. The image display device manufactured using the adhesive member of the present embodiment includes a non-self-luminous display unit, a backlight unit, and an adhesive member of the present embodiment disposed between these units (however, affixed) If the non-self-luminous display unit is a unit that is driven by a power source such as a liquid crystal display module unit, etc. A drive circuit such as an FPC connected to the unit is further provided. In this case, for example, when both units are connected to one end and the other end of the bent FPC, for example, an image mounted on an electronic device such as a smartphone, a mobile phone, a tablet PC, a notebook computer, or a wearable terminal. In the display device, a strong repulsive force that tends to peel off both units from each other by the bent FPC is likely to act. However, in the pressure-sensitive adhesive member according to the present embodiment, since both of the units have a strong repulsive force due to excellent peeling resistance to the adherent surface of the pressure-sensitive adhesive layer (particularly, a polycarbonate substrate that easily generates outgas in a high-temperature environment). However, it is possible to prevent the two units from being separated from each other.

  EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to the following examples.

(1) Used raw material for preparation of pressure-sensitive adhesive composition In preparing the pressure-sensitive adhesive composition, the following raw materials were used. The abbreviations and material names of the raw materials used are shown below.

<Monomer>
(A) Acrylic monomer (acrylic monomer having a homopolymer glass transition temperature of 0 ° C. to 80 ° C. and having no crosslinkable functional group)
MA: methyl acrylate (glass transition temperature of homopolymer: 10 ° C.)

(B) Carboxyl-containing monomer AA: Acrylic acid (homopolymer glass transition temperature: 106 ° C.)

(C) Other monomers (monomers not corresponding to the above (a) and (b))
2-EHA: 2-ethylhexyl acrylate (homopolymer glass transition temperature: -70 ° C)
-BA: butyl acrylate (glass transition temperature of homopolymer: -54 ° C)
2-HEA: 2-hydroxyethyl acrylate (glass transition temperature of homopolymer: −15 ° C.)
M1: (number average molecular weight: 6000 methacryloyl group-containing macromonomer, homopolymer glass transition temperature: 100 ° C.)

<Tackifying resin>
・ TF1 (polymerized rosin ester-based tackifying resin with a softening point of 135 ° C)
・ TF2 (polymerized rosin ester-based tackifying resin having a softening point of 160 ° C.)
・ Acrylic TF3 (Tackifying resin prepared by the procedure shown below)

-Procedure for preparing acrylic TF3-
Cyclohexyl methacrylate [Glass transition temperature of homopolymer (polycyclohexyl methacrylate): 66 ° C.]: 92 parts by weight, n-butyl methacrylate: 4 parts by weight, acrylic acid: 4 parts by weight, 2-mercaptoethanol: 15 parts by weight Azobisisobutyronitrile: 0.2 parts by weight and 100 parts by weight of toluene as a polymerization solvent were put into a separable flask and stirred for 1 hour while introducing nitrogen gas. After removing oxygen in the polymerization system in this way, the temperature was raised to 70 ° C., reacted for 3 hours, and further reacted at 75 ° C. for 2 hours to obtain an acrylic TF3 having a solid concentration of 50% by weight. A solution containing was obtained. The weight average molecular weight of acrylic TF3 in this solution was 7000.

<Curing agent>
・ L-45 (isocyanate-based curing agent, manufactured by Soken Chemical Co., Ltd.)

(2) Preparation of adhesive member <Example 1>
-Preparation of adhesive layer forming coating liquid-
A 4-neck flask capable of nitrogen substitution was charged with 100 parts by weight of a monomer mixture in which 2-EHA, MA, AA, 2-HEA and M1 were blended in the proportions shown in Table 1 and 150 parts by weight of ethyl acetate. The mixture was heated to 68 ° C. and 0.07 part by weight of azobisisobutyronitrile was added to initiate polymerization. Two hours after the start of the polymerization, 0.15 parts by weight of azobisisobutyronitrile was added dropwise over 10 minutes, and after 6 hours and 30 minutes from the start of the polymerization, 100 parts by weight of ethyl acetate was additionally added to terminate the polymerization. A polymer solution containing a polymer was obtained. It was 950,000 when the weight average molecular weight Mw of the obtained acrylic polymer was measured by GPC method.

  Next, a tackifier resin (TF1) and a curing agent (L-45) were further mixed into the polymer solution to prepare a pressure-sensitive adhesive layer-forming coating solution. At this time, 20 parts by weight of the tackifier resin (TF1) and 0.7 parts by weight of the curing agent (L-45) with respect to 100 parts by weight of the solid content (acrylic polymer) contained in the polymer solution. Mixed in parts.

-Production of adhesive members-
An adhesive member 10C having the layer structure shown in FIG. 3 was prepared by the following procedure. First, as a resin film 24T, aluminum is deposited on one surface of a PET film having a thickness of 12 μm (M310E12, manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.) so that the deposition film thickness is 50 nm under the condition of 10 ⁻² Pa. Thus, the reflective layer 24R was formed. Next, on the other side of the PET film, 100 parts by weight of polyester resin Byron 20SS manufactured by Toyobo Co., Ltd., 30 parts by weight of black dye BM1500 manufactured by Kouka Chemical Co., Ltd., and Coronate manufactured by Nippon Polyurethane Industry Co., Ltd. A black ink mixed with 2 parts by weight of L was printed to form a light-shielding layer 24S composed of a black print layer having a thickness of 5 μm. Thereby, the base material 20C which consists of a laminated body which laminated | stacked the reflection layer 24R, the resin film 24T, and the light shielding layer 24S in this order was obtained.

  Next, on the release treated surface of the release PET film (MRF38, manufactured by Mitsubishi Chemical Polyester Film), by applying the adhesive layer forming coating solution with a doctor blade so that the film thickness after drying is 20 μm, The sheet | seat in which the adhesive layer 30 was formed in the single side | surface of the peeling sheet 40 was obtained. And after sticking this sheet | seat on both surfaces of 20 C of base materials, the adhesive member 10C shown in FIG. 3 was obtained by making it age | cure | ripen at room temperature for 7 days.

  In addition, when the reflectance and the transmittance were measured in a state where the release sheet 40 was peeled off from the obtained adhesive member 10C, the 550 nm wavelength light on the surface provided with the reflective layer 24R measured according to JIS Z 8730 was measured. The reflectance was 60% or more, and the total light transmittance measured in accordance with JIS K 7361 was 0.5% or less, and it was confirmed that the film had sufficient reflectivity and light shielding properties.

<Examples 2-7, Comparative Examples 1-6>
A pressure-sensitive adhesive member was produced in the same manner as in Example 1 except that the types and blending ratios of various raw materials used for adjusting the pressure-sensitive adhesive layer-forming coating solution were changed as shown in Table 1. However, the polymerization time for synthesizing the acrylic polymer was appropriately adjusted as necessary so that a desired weight average molecular weight was obtained. For the adhesive members of Examples 2 to 6 and Comparative Examples 1 to 6, the reflectance and total light transmittance were evaluated in the same manner as in Example 1. In any of the Examples and Comparative Examples, the reflectance was 60% or more. And, it was confirmed that the total light transmittance was 0.5% or more and had sufficient reflectivity and light shielding properties.

(3) Various measurement and test methods <GPC measurement method>
Measuring device: HLC-8120GPC (manufactured by Tosoh Corporation)
GPC column configuration: The following five columns (all manufactured by Tosoh Corporation)
(1) TSK-GEL HXL-H (guard column)
(2) TSK-GEL G7000HXL
(3) TSK-GEL GMHXL
(4) TSK-GEL GMHXL
(5) TSK-GEL G2500HXL
Diluted with tetrahydrofuran so that the sample concentration is 1.0 mg / cm ³ Mobile phase solvent: Tetrahydrofuran Flow rate: 1.0 cm ³ / min
Column temperature: 40 ° C.

<Constant load peel test>
A pressure-sensitive adhesive layer was formed on one side of a PET film having a thickness of 25 μm under the same conditions as those for the pressure-sensitive adhesive members of Examples and Comparative Examples. Next, the surface of the formed pressure-sensitive adhesive layer and the PET release film were formed. And aged for 7 days, and finally cut into a size of 20 × 50 mm to prepare a test piece. Then, the test piece which peeled the PET peeling film was bonded together to the lower surface side of the polycarbonate substrate arrange | positioned so that the front and back may form a parallel with a horizontal direction. Next, a test piece when left at a temperature of 85 ° C. for 180 minutes with a load of 100 g applied to the lower end in the vertical direction at one end in the longitudinal direction of the test piece attached to the polycarbonate substrate. The peel distance (mm) in the longitudinal direction or the time (min) until dropping was measured. In addition, in the good determination (◯ determination), the peeling distance is 10.0 mm or less.

<Ball tack test>
J. et al. It was measured by the Dow method. Specifically, the pressure-sensitive adhesive layer exposes the pressure-sensitive adhesive sheet from which the PET release film has been peeled off from a test piece having the same layer structure as that prepared in the constant load peel test (however, a test piece cut to a width of 10 cm). It attached to the inclined surface of 30 degrees of inclination angles. Next, the steel ball was run from the upper side of the inclined surface, and then slid on the adhesive surface (adhesive layer surface). The running distance at this time was 10 cm, and the running distance was 10 cm. The temperature was 23 ° C. and the humidity was 65% RH. Then, a sliding test was performed while changing the diameter of the steel ball, and the maximum diameter of the steel ball that stopped sliding in the adhesive surface was obtained. In addition, the diameter of the used steel ball is X / 32 inches (where X is an integer in the range of 1 to 32), and the numerical values shown in Table 1 mean the value of X. Note that in the good determination (◯ determination), the X value is 6 or more.

<Cutability>
The adhesive member of each Example and Comparative Example was punched 30 times with a cutter blade, and adhesion of the adhesive to the cutter blade and the cut surface were visually observed.
○: There is no adhesion of the adhesive to the cutter blade, and the cut surface is not rough.
X: Adhesive adhesion to the cutter blade was confirmed, and the cut surface was rough.

10, 10A, 10B, 10C, 10D: Adhesive member 20, 20A, 20B, 20C, 20D: Base material 22R: Reflective resin film 22S: Light-shielding resin film 24R: Reflective layer 24S: Light-shielding layer 24T: Resin film 30: Adhesive layer 40: release sheet

Claims (7)

The glass transition temperature at the time of constituting the homopolymer is 0 ° C. to 80 ° C., and 10 to 30% by weight of an acrylic monomer having no crosslinkable functional group and 2 to 2 monomers containing a carboxyl group An acrylic polymer obtained by copolymerizing a monomer mixture containing 7% by weight,
The acrylic pressure-sensitive adhesive composition for light-shielding double-sided pressure-sensitive adhesive members, wherein the acrylic polymer has a weight average molecular weight of 750,000 to 12,500.   The acrylic pressure-sensitive adhesive composition for light-shielding double-sided pressure-sensitive adhesive members according to claim 1, wherein the surface to be adhered is used for sticking to a member made of polycarbonate resin.   The acrylic pressure-sensitive adhesive composition for light-shielding double-sided pressure-sensitive adhesive members according to claim 1, further comprising a rosin ester resin. A film-like substrate;
A pressure-sensitive adhesive layer provided at least on one side of the base material and including an acrylic pressure-sensitive adhesive composition for a light-shielding double-sided pressure-sensitive adhesive member according to any one of claims 1 to 3. A light-shielding double-sided adhesive member. A non-self-luminous display unit;
A backlight unit;
An image display device comprising at least the light-shielding double-sided adhesive member according to claim 4 disposed between the non-self-luminous display unit and the backlight unit.   The image display apparatus according to claim 5, wherein the non-self-luminous display unit is a liquid crystal display module unit. 7. The image display device according to claim 5, wherein a surface of the backlight unit that is in contact with the light-shielding double-sided pressure-sensitive adhesive member is made of a polycarbonate resin.

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