JP6565541B2 - Double-sided adhesive sheet and optical member - Google Patents

Description

  The present invention relates to a double-sided pressure-sensitive adhesive sheet. Furthermore, this invention relates to the optical member which bonded the double-sided adhesive sheet to the electrically-conductive member.

  In recent years, display devices such as a liquid crystal display (LCD) and input devices used in combination with a display device such as a touch panel have been widely used in various fields. In the manufacture of these display devices and input devices, a transparent double-sided pressure-sensitive adhesive sheet is used for the purpose of bonding optical members. For example, a double-sided pressure-sensitive adhesive sheet is widely used for bonding two members such as a conductive member provided with a transparent electrode film such as ITO (Indium Tin Oxide) on a transparent support and a cover glass, a touch panel, and a display device. Yes.

  However, when a double-sided PSA sheet is used for a conductive member provided with a transparent electrode film such as ITO, corrosion of the metal surface may occur due to acidic groups such as carboxyl groups contained in the base polymer structural unit. When such corrosion of the metal surface occurs, the original function such as optical recording is adversely affected. For this reason, a double-sided PSA sheet that does not cause corrosion of the metal surface has been developed. For example, Patent Document 1 proposes an adhesive sheet that does not corrode the metal surface, can be easily peeled off from the metal surface during reworking, and has good transparency.

Japanese Patent Laid-Open No. 2007-077388

  Generally, the conductive member has a structure in which ITO or the like is patterned on a transparent support. For this reason, when the adhesive sheet described in Patent Document 1 is bonded to such a conductive member, the conductive portion (electrode portion) does not corrode, but the pattern structure of the conductive portion is visualized.

  In order to make the pattern structure of the conductive part invisible, a method of adjusting the refractive index of the pressure-sensitive adhesive sheet can be considered. For example, the refractive index can be adjusted by adding fine particles or the like. However, the inventors have clarified that glare called sparkling may occur in an adhesive sheet to which fine particles or the like are added. In such a case, it becomes a problem because the visibility of the display image deteriorates.

  That is, when the conventional pressure-sensitive adhesive sheet is used, making the pattern structure of the conductive portion invisible and suppressing the occurrence of sparkling are not compatible, and improvement in visibility has been demanded. Accordingly, the present inventors have aimed to provide a pressure-sensitive adhesive sheet that can make the pattern of the conductive part invisible and further suppress the occurrence of sparkling in order to solve the problems of the conventional technology. We proceeded with examination.

Result of intensive studies to solve the above problems, the present inventors have found that, in the double-sided pressure-sensitive adhesive sheet, and b ^* values measured by the transmitted light, and b ^* values measured by the reflected light, and a haze value, By making the relationship between the diameter of the fine particles or the diameter of the sea island structure derived from the incompatible resin a predetermined relationship, the pattern of the conductive portion can be made invisible and the occurrence of sparkling can be suppressed. I found out.
Specifically, the present invention has the following configuration.

[1] Double-sided pressure-sensitive adhesive sheet satisfying the condition of the following formula (1) and having a haze value of 5% or more;
4.0 <(Δb ^* × 100) / (Hz × φ) <300 Formula (1)
In the formula (1), Δb ^* = b _T ^* −b _R ^* , b _T ^* represents the b ^* value of the double-sided pressure-sensitive adhesive sheet measured with transmitted light, and b _R ^* is the double-sided pressure-sensitive adhesive sheet measured with reflected light. B ^* value, Hz represents the haze value of the double-sided PSA sheet, and φ represents the average particle diameter of the fine particles or the diameter of the island part derived from the incompatible resin.
[2] The double-sided pressure-sensitive adhesive sheet according to [1], comprising a base polymer and fine particles.
[3] The double-sided pressure-sensitive adhesive sheet according to [2], wherein the content of the fine particles is 1 to 50% by mass with respect to the total mass of the base polymer.
[4] The double-sided pressure-sensitive adhesive sheet according to [2] or [3], wherein the average particle size of the fine particles is 0.1 to 4 μm.
[5] The double-sided pressure-sensitive adhesive sheet according to [1], containing a base polymer and an incompatible resin.
[6] The double-sided pressure-sensitive adhesive sheet according to [5], wherein the content of the incompatible resin is 1 to 50% by mass with respect to the total mass of the base polymer.
[7] The double-sided adhesive according to any one of [2] to [6], wherein the base polymer includes at least one selected from an acrylic polymer, a urethane polymer, a polyester polymer, and a rubber polymer. Sheet.
[8] The double-sided pressure-sensitive adhesive sheet according to any one of [1] to [7], wherein the double-sided pressure-sensitive adhesive sheet is used for bonding a conductive member provided with a conductive part on a part of the transparent support.
[9] A double-sided pressure-sensitive adhesive sheet with a release sheet, wherein the release sheet is laminated on at least one surface of the double-sided pressure-sensitive adhesive sheet according to any one of [1] to [8].
[10] A pressure-sensitive adhesive sheet with a transparent substrate, comprising the double-sided pressure-sensitive adhesive sheet according to any one of [1] to [8] and a transparent substrate layer.
[11] An optical member comprising the double-sided pressure-sensitive adhesive sheet according to any one of [1] to [8] and a conductive member provided with a conductive part on a part of the transparent support.

  According to this invention, even if it is a case where a double-sided adhesive sheet is used for the electrically-conductive member provided with electroconductive parts, such as ITO, the pattern of an electroconductive part can be made invisible and generation | occurrence | production of sparkling can be suppressed. For this reason, if the double-sided adhesive sheet of this invention is used, the optical member with the favorable visibility of a screen can be obtained.

FIG. 1 is a schematic cross-sectional view showing an example of the double-sided pressure-sensitive adhesive sheet of the present invention. FIG. 2 is a schematic cross-sectional view showing an example of the pressure-sensitive adhesive sheet with a transparent substrate of the present invention. FIG. 3 is a schematic sectional view showing an example of the optical member of the present invention.

  Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be made based on representative embodiments and specific examples, but the present invention is not limited to such embodiments. In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

(Double-sided adhesive sheet)
The double-sided pressure-sensitive adhesive sheet of the present invention satisfies the condition of the following formula (1) and has a haze value of 5% or more.
4.0 <(Δb ^* × 100) / (Hz × φ) <300 Formula (1)
In the formula (1), Δb ^* = b _T ^* −b _R ^* , b _T ^* represents the b ^* value of the double-sided pressure-sensitive adhesive sheet measured with transmitted light, and b _R ^* is the double-sided pressure-sensitive adhesive sheet measured with reflected light. B ^* value, Hz represents the haze value of the double-sided pressure-sensitive adhesive sheet, φ represents the average particle diameter of the fine particles or the diameter of the island part derived from the incompatible resin

  As shown in FIG. 1A, the double-sided pressure-sensitive adhesive sheet of the present invention may have only the double-sided pressure-sensitive adhesive sheet 13 that does not have an intermediate support layer or the like. Moreover, even if the double-sided pressure-sensitive adhesive sheet of the present invention has an intermediate support layer 14 and has a pressure-sensitive adhesive layer 20 on both sides of the intermediate support layer 14 as shown in FIG. Good. When the double-sided pressure-sensitive adhesive sheet 13 has only a double-sided pressure-sensitive adhesive sheet that does not have the intermediate support layer 14 or the like, the double-sided pressure-sensitive adhesive sheet 13 includes the pressure-sensitive adhesive layer 20. The pressure-sensitive adhesive layer 20 may be a single layer or multiple layers.

In the present invention, the haze value refers to a value measured by a method based on JIS K 7136. When the double-sided pressure-sensitive adhesive sheet of the present invention is composed only of a double-sided pressure-sensitive adhesive sheet, it is difficult to measure the haze value of the double-sided pressure-sensitive adhesive sheet, and thus the double-sided pressure-sensitive adhesive sheet is pasted on a slide glass (product number: S9112) manufactured by Matsunami Glass. Further, a transparent PET film (CPET75H manufactured by Shin Tac Kasei Co., Ltd.) is bonded to the opposite adhesive surface, and a laminated body in which glass, a double-sided adhesive sheet, and a PET film are laminated in this order is produced. This laminate is subjected to an autoclave (pressure defoaming) treatment for 30 minutes under conditions of 0.5 MPa and 40 ° C., and a haze value is measured using NDH4000 manufactured by Nippon Denshoku Industries Co., Ltd. This haze value can be set as the haze value of the double-sided pressure-sensitive adhesive sheet of the present invention.
In addition, in the case of the double-sided pressure-sensitive adhesive sheet having an intermediate support layer, the double-sided pressure-sensitive adhesive sheet of the present invention is a laminate obtained by laminating a slide glass and a transparent PET film and a double-sided pressure-sensitive adhesive sheet and subjected to pressure defoaming. The haze value can be the haze value of the double-sided pressure-sensitive adhesive sheet of the present invention. However, since the smoothness of the pressure-sensitive adhesive layer may drop when the release sheet is peeled off, and the haze may appear to rise, glass and a transparent PET film are formed as in the case of the above-described double-sided pressure-sensitive adhesive sheet alone. It is more preferable to measure the haze with a laminate using the above, and in the present invention, the value measured by such a measuring method is defined as the haze value.

In the present invention b _T ^* represents the b ^* value of the double-sided pressure-sensitive adhesive sheet was measured in transmitted light, b _R ^* represents a b ^* value of the double-sided pressure-sensitive adhesive sheet was measured by reflected light. b _T ^* is a b ^* value measured by the transmitted light of a laminate in which glass, a double-sided pressure-sensitive adhesive sheet, and a PET film are laminated in the same manner as the haze measurement sample described above. Specifically, using a spectral color difference meter “Spectro Color Meter SE2000” manufactured by Nippon Denshoku Industries Co., Ltd., the value is measured in the transmission measurement mode with the PET side of the laminate being set to the light source side. . b _R ^* is a value measured in the reflection measurement mode by setting the laminate so that the PET side becomes the light source side, and setting the black backing plate provided as a standard in the apparatus on the opposite glass surface. φ is the average particle diameter of fine particles or the diameter of island parts derived from an incompatible resin (hereinafter also referred to as a dotted part of a sea-island structure), measured by a method described later.

In the present invention, the b ^* value (b _T ^* ) of the double-sided pressure-sensitive adhesive sheet measured with transmitted light, the b ^* value (b _R ^* ) of the double-sided pressure-sensitive adhesive sheet measured with reflected light, the haze value of the double-sided pressure-sensitive adhesive sheet, The relationship between the average particle diameter of the fine particles or the diameter of the island portion derived from the incompatible resin is set as the predetermined condition as described above. When the haze value of the double-sided pressure-sensitive adhesive sheet is increased, the light that has entered the double-sided pressure-sensitive adhesive sheet is appropriately diffused, and the pattern of the conductive part is hardly visible from the outside. Further, the effect of suppressing the occurrence of sparkling is obtained when the difference between the b ^* value (b _T ^* ) of the double-sided PSA sheet measured with transmitted light and the b ^* value (b _R ^* ) of the double-sided PSA sheet measured with reflected light is larger. It is done. On the other hand, if the haze value is large, the sparkling occurrence suppressing effect is reduced. The present inventors have ascertained the above and found that when the relational expression such as Expression (1) is satisfied, the pattern of the conductive portion can be made invisible and the occurrence of sparkling can be suppressed. That is, when the double-sided pressure-sensitive adhesive sheet of the present invention is used, both the invisibility of the conductive part pattern and the suppression of the occurrence of sparkling can be achieved. For this reason, when a conductive member and a display apparatus are bonded using the double-sided adhesive sheet of this invention, the display screen of a display apparatus can be visually recognized on the transparent support body side of a conductive member.

In the above formula (1), the value of (Δb ^* × 100) / (Hz × φ) only needs to be larger than 4, preferably larger than 5, and more preferably larger than 10. Further, the value of (Δb ^* × 100) / (Hz × φ) may be smaller than 300, preferably smaller than 200, and more preferably smaller than 150. By setting the value of (Δb ^* × 100) / (Hz × φ) in the above range, the double-sided pressure-sensitive adhesive sheet of the present invention can exhibit a sparkling suppressing effect more.

  The haze value of the double-sided pressure-sensitive adhesive sheet may be 5% or more. Note that the haze value may be 10% or more, 15% or more, or 20% or more as long as it satisfies the above-described relational expression (1). Further, the haze value may be 40% or less, 35% or less, 30% or less, or 25% or less. By setting the haze value of the double-sided pressure-sensitive adhesive sheet within the above range, the pattern of the conductive part can be more effectively invisible.

  The thickness of the double-sided PSA sheet is preferably 10 μm or more, more preferably 15 μm or more, and further preferably 20 μm or more. The thickness of the double-sided pressure-sensitive adhesive sheet is preferably 200 μm or less, more preferably 180 μm or less, further preferably 150 μm or less, still more preferably 100 μm or less, and 75 μm or less. Is particularly preferred. By setting the thickness of the double-sided pressure-sensitive adhesive sheet within the above range, the pattern of the conductive part can be more effectively invisible, and a sparkling suppressing effect can be further exhibited. Furthermore, sufficient adhesive force can be ensured, and even when used for a long time, floating and peeling are less likely to occur.

  Although there is no restriction | limiting in particular in the refractive index of the base polymer and particle | grains used for a double-sided adhesive sheet, It is preferable that the refractive index difference of a base polymer and particle | grain is 0.02 or more. When this refractive index difference is 0.02 or more, an increase in haze when particles are added is effectively expressed.

  It is preferable that the double-sided pressure-sensitive adhesive sheet of the present invention is used for bonding a conductive member provided with a conductive part on a part of a transparent support. In the conductive member, the surface of the transparent support on which no conductive part is formed functions as a non-conductive part. The double-sided pressure-sensitive adhesive sheet of the present invention is bonded so as to be in direct contact with at least part of the conductive part of the conductive member, and preferably is in direct contact with at least part of the conductive part and at least part of the non-conductive part. Are pasted together. The conductive part is preferably formed by patterning ITO or the like on a transparent support.

(Adhesive composition)
The pressure-sensitive adhesive layer of the double-sided pressure-sensitive adhesive sheet of the present invention is formed from a pressure-sensitive adhesive composition. The pressure-sensitive adhesive composition contains a base polymer as a main component. That is, the double-sided pressure-sensitive adhesive sheet of the present invention contains a base polymer as a main component. In addition, in this specification, a main component means the component contained 50 mass% or more with respect to the total mass of an adhesive composition or a double-sided adhesive sheet.

(Base polymer)
The base polymer is preferably one having transparency to the extent that visibility is not lowered. Specifically, the base polymer preferably contains at least one selected from an acrylic polymer, a urethane polymer, a polyester polymer, and a rubber polymer. Of these, the base polymer is preferably composed of an acrylic polymer. Thereby, the double-sided adhesive sheet excellent in transparency and adhesiveness can be formed.

<1. Acrylic polymer>
As an acrylic polymer, a copolymer containing an acrylic monomer unit (a2) having a non-crosslinkable (meth) acrylic acid ester unit (a1) as a main component and having a crosslinkable functional group is used. It is preferable. In the present specification, the “unit” is a repeating unit (monomer unit) constituting the polymer.

  The acrylic monomer unit (a2) having a crosslinkable functional group serves as a reaction point when a crosslinker is used, and the adhesive force, cohesive force, and heat resistance can be controlled by crosslinking. The usage-amount of the acrylic monomer unit (a2) which has a crosslinkable functional group in an acrylic polymer shall be 0.01-20 mass% as a ratio occupied in the total monomer mass which comprises a copolymer. Is preferred. More preferably, it is 0.1-15 mass%, More preferably, it is 0.5-10 mass%. By setting the content of the crosslinkable acrylic monomer unit (a2) within the above range, the crosslinkability can be sufficiently exerted, and further necessary adhesive physical properties can be maintained.

As the non-crosslinkable (meth) acrylic acid ester unit (a1) constituting the acrylic polymer, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, (Meth) acrylic such as isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate, isostearyl (meth) acrylate Examples include acid alkyl ester monomers. Two or more of these may be used in combination as required.
In the present invention, “(meth) acrylate” means containing both “acrylate” and “methacrylate”, and “(meth) acrylic acid” means “acrylic acid” and “methacrylic acid”. Is meant to include both.

  Examples of the acrylic monomer unit (a2) having a crosslinkable functional group include (meth) acrylic acid, maleic acid, maleic anhydride, itaconic acid, fumaric acid, fumaric anhydride and other carboxyl group-containing monomers, 2- Hydroxyl-containing monomers such as hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, polyethylene glycol (meth) acrylate, (meth) acrylamide, morpholyacrylamide, N , N-dimethylaminoethyl acrylate, N-tert-butylaminoethyl acrylate and other amino group-containing (meth) acrylic acid esters, glycidyl (meth) acrylate and other epoxy groups. Two or more of these may be used in combination as required. In addition, when the electroconductive part of the electroconductive member which bonds the double-sided adhesive sheet of this invention is ITO, it is preferable to use the monomer which has functional groups other than a carboxyl group containing monomer. In this case, the ratio of the carboxyl group-containing monomer unit contained in the acrylic monomer unit (a2) having a crosslinkable functional group is 1% or less with respect to the total mass of the acrylic monomer unit. Preferably, it is 0.1% or less, more preferably 0%. By making the ratio of the carboxyl group-containing monomer unit contained in the acrylic monomer unit (a2) within the above range, the corrosiveness of the conductive part to the metal wiring can be suppressed.

  The acrylic polymer has a monomer unit other than the non-crosslinkable (meth) acrylic acid ester unit (a1) and the acrylic monomer unit (a2) having a crosslinkable functional group, if necessary. May be. Any other monomer may be used as long as it is copolymerizable with a non-crosslinkable (meth) acrylic acid ester and an acrylic monomer having a crosslinkable functional group. Examples of other monomers include (meth) acrylonitrile, vinyl acetate, styrene, vinyl chloride, vinyl pyrrolidone, vinyl pyridine and the like. In addition, it is preferable that it is 0-20 mass%, and, as for content of the other monomer unit in an acrylic polymer, it is more preferable that it is 0-15 mass%.

  The weight average molecular weight of the acrylic polymer is preferably 100,000 to 2,000,000, more preferably 300,000 to 1,500,000. By setting the weight average molecular weight within the above range, sufficient durability and flexibility can be ensured. The weight average molecular weight of the acrylic polymer is a value before being crosslinked with a crosslinking agent. The weight average molecular weight is a value determined by size exclusion chromatography (SEC) and determined on a polystyrene basis.

  When polymerizing an acrylic polymer, for example, a solution polymerization method can be applied. Examples of the solution polymerization method include an ionic polymerization method and a radical polymerization method. Examples of the solvent used at that time include tetrahydrofuran, chloroform, ethyl acetate, toluene, hexane, acetone, methyl ethyl ketone, and the like.

<Crosslinking agent>
When the pressure-sensitive adhesive composition used in the present invention is a copolymer using a monomer having a functional group, the pressure-sensitive adhesive can be subjected to a crosslinking treatment by blending a crosslinking agent.
Examples of the crosslinking agent include isocyanate compounds, epoxy compounds, oxazoline compounds, aziridine compounds, metal chelate compounds, butylated melamine compounds, and these may be used in combination of two or more, if necessary. It is preferable to select in consideration of the reactivity with the functional group used in the coalescence.
Among these crosslinking agents, an isocyanate compound and an epoxy compound are preferred because the acrylic polymer can be easily crosslinked. Examples of the isocyanate compound include tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. Examples of the epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexanediol diester. Glycidyl ether, tetraglycidyl xylenediamine, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, etc. Can be mentioned.

In the pressure-sensitive adhesive composition, the content of the crosslinking agent is appropriately selected according to the desired physical properties of the pressure-sensitive adhesive and is not particularly limited. For example, 0.01 to 5 parts by mass with respect to 100 parts by mass of the acrylic polymer Preferably, 0.03 to 3 parts by mass is more preferable. If the content of the crosslinking agent is not less than the above lower limit value, the durability is excellent, and if it is not more than the above upper limit value, the adhesion to the adherend is excellent.
Moreover, it is preferable that it is 0.01-5.0 mass% with respect to the total mass of an adhesive composition, and, as for content of a crosslinking agent, it is more preferable that it is 0.02-2.0 mass%.
The gel fraction of the crosslinked pressure-sensitive adhesive composition crosslinked by the above is 20 to 98%, preferably 30 to 90%, more preferably 40 to 80%. If the gel fraction is 20% or more, sufficient cohesive force can be obtained, and if it is 98% or less, sufficient adhesive force and wettability to the adherend can be obtained. In addition, the gel fraction described here is a percentage display value of a value obtained by dividing the dry weight of the residue obtained by removing soluble components from the pressure-sensitive adhesive composition by the mass of the pressure-sensitive adhesive composition before immersion. . When removing soluble components from the pressure-sensitive adhesive composition, a predetermined amount of the pressure-sensitive adhesive composition is immersed in a solvent such as ethyl acetate or toluene that is twice or more the mass of the pressure-sensitive adhesive composition. After being treated at 40 ° C. for 24 hours, it is filtered through a 150 mesh wire mesh.

<2. Urethane polymer>
Examples of the urethane polymer include those obtained as a reaction product of a polyol compound and an isocyanate compound. Examples of the polyol compound include polyester polyol, polyether diol, polyacetal diol and the like. Examples of the isocyanate compound include tolylene diisocyanate and phenylene diisocyanate. These components can be reacted using two or more kinds.

<3. Polyester polymer>
Examples of the polyester polymer include those that are polycondensed from a polybasic acid component and a polyol component. Examples of the polybasic acid used include terephthalic acid, isophthalic acid, and diphenylcarboxylic acid. Examples of the polyol component include, but are not limited to, ethylene glycol and diethylene glycol. These monomer components may be copolymerized using two or more kinds.

<4. Rubber polymer>
Examples of rubber polymers include styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), hydrogenated styrene block copolymer, styrene-butadiene rubber (SBR). ), Polyisoprene rubber (IR), polyisobutylene (PIB), butyl rubber (IIR) and the like. These synthetic rubbers may be used alone or in combination of two or more.

Among these, the rubber-based polymer is preferably a styrene-based copolymer, more preferably a hydrogenated product of a styrene-based block copolymer, and further preferably a styrene-hydrogenated isoprene-styrene copolymer. preferable.
The weight average molecular weight (Mw) of the rubber polymer is 10,000 to 10,000,000, more preferably 50,000 to 800,000.

(Haze adjustment)
In order for the double-sided pressure-sensitive adhesive sheet to satisfy the above-mentioned condition of the formula (1) and the haze value to be 5% or more, (i) a method of mixing fine particles in the pressure-sensitive adhesive composition, or (ii) a pressure-sensitive adhesive composition It is possible to employ a method of mixing an incompatible resin. In addition, you may use combining the method of (i) and (ii).

<Fine particles>
The fine particles may be fine particles having a function of diffusing light incident on the double-sided pressure-sensitive adhesive sheet, and may be organic fine particles or inorganic fine particles. The fine particles used in the present invention function as light diffusing fine particles.

  Examples of the inorganic fine particles include fine particles made of silica, calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, talc, aluminum oxide, titanium oxide, and the like.

  Examples of the organic fine particles include polystyrene resins, polyolefin resins such as polyethylene and polypropylene, (meth) acrylic resins such as polymethacrylate resins and polyacrylate resins, epoxy resins, silicone resins, and crosslinked resins. Resin particles comprising a copolymerized resin in which two or more monomers selected from the formed crosslinked polymer, ethylene, propylene, styrene, methyl methacrylate, benzoguanamine, formaldehyde, melamine, butadiene and the like are copolymerized Can be used.

In addition, fine particles composed of a silicon-containing compound having an intermediate structure between inorganic and organic (for example, Tospearl series manufactured by Momentive Performance Materials Japan) can be used as the light diffusing fine particles.
These fine particles may be used alone or in combination of two or more. Further, organic fine particles, inorganic fine particles, and fine particles having an intermediate structure between inorganic and organic can be used in combination. The fine particles used in the present invention are preferably those which do not excessively reduce the total light transmittance of the double-sided PSA sheet, and acrylic beads and silica beads having high transparency are suitable.

The shape of the fine particles is not particularly limited, but is preferably spherical because light can be uniformly diffused. Moreover, it is preferable that the average particle diameter (primary particle diameter) of microparticles is 0.1-4 micrometers, and it is more preferable that it is 1-4 micrometers. Here, in this specification, the average particle diameter can be measured using a transmission electron microscope or a scanning electron microscope. Specifically, the maximum length (Dmax) and maximum length vertical length (DV-max) of the particle image of the fine particles are measured, and the geometric mean value (Dmax × DV-max) ^1/2 is defined as the particle diameter. be able to. The maximum length (Dmax) is the maximum length at two points on the contour of the particle image, and the maximum vertical length (DV-max) is when the particle image is sandwiched between two straight lines parallel to the maximum length. The shortest length between these two straight lines. With this method, the particle diameter of 100 arbitrary fine particles is measured, and the average value is taken as the average particle diameter of the fine particles. By making the average particle diameter of the fine particles within the above range, when the double-sided PSA sheet is visually recognized with the naked eye, there is no feeling of granularity or foreign matter, and the b ^* value and haze value of the double-sided PSA sheet are within a predetermined range. It can be.

  The content of the fine particles in the double-sided PSA sheet is preferably 1 to 50% by mass, more preferably 5 to 40% by mass, and 8 to 30% by mass with respect to the total mass of the base polymer. Further preferred. By setting the content of the fine particles within the above range, the double-sided pressure-sensitive adhesive sheet easily satisfies the condition of the above-described formula (1) and has a haze value of 5% or more.

  When the base polymer is acrylic, the base polymer has a refractive index of about 1.47. Therefore, it is preferable to use fine particles having a refractive index of 1.49 or more or 1.45 or less for the double-sided PSA sheet.

<Incompatible resin>
The b ^* value and haze value of the double-sided pressure-sensitive adhesive sheet can be adjusted so as to satisfy the above conditions by using an incompatible resin as an additive to be mixed with the pressure-sensitive adhesive composition. Here, in the present specification, the incompatible resin refers to a resin having low compatibility with the base polymer, and when the base polymer and the incompatible resin are mixed, the haze value increases in accordance with the mixing amount. It means what goes on. Specifically, a resin having a haze of 20% or more when the base polymer and the resin are mixed at 1: 1 is referred to as an incompatible resin. By using such an incompatible resin, the double-sided PSA sheet can satisfy the condition of the above-described formula (1) and have a haze value of 5% or more.

  Examples of the incompatible resin include a tackifier and a styrene copolymer resin. Examples of the tackifier include rosin resins, terpene resins, terpene phenol resins, coumarone indene resins, styrene resins, xylene resins, phenol resins, petroleum resins, and the like. Among them, the tackifier is preferably a terpene resin, more preferably an aromatic modified terpene resin, and further preferably an aromatic modified hydrogenated terpene resin. As the aromatic modified hydrogenated terpene resin, tackifier (Yasuhara Chemical, K100) or the like can be used.

  The content of the incompatible resin in the double-sided PSA sheet is preferably 1 to 50% by mass, more preferably 5 to 40% by mass, and 8 to 30% by mass with respect to the total mass of the base polymer. More preferably it is. The above content varies depending on the type of incompatible resin to be added. For example, when an aromatic modified hydrogenated terpene resin or a styrene-acrylic copolymer is used as the incompatible resin, The above range is preferable. By setting the content of the incompatible resin within the above range, the double-sided pressure-sensitive adhesive sheet easily satisfies the condition of the above-described formula (1) and has a haze value of 5% or more.

  When an incompatible resin is added to the double-sided pressure-sensitive adhesive sheet, the base polymer and the incompatible resin in the double-sided pressure-sensitive adhesive sheet are not compatible with each other, thereby forming a sea-island structure. Here, the sea-island structure means a structure in which incompatible resins are scattered in an island shape in the base polymer. In the present specification, the region where the incompatible resin is scattered in an island shape is referred to as an island portion derived from the incompatible resin. The diameter of the island portion derived from the incompatible resin in the double-sided PSA sheet is preferably 0.1 to 4 μm, and more preferably 0.5 to 3 μm.

The diameter of the island portion derived from the incompatible resin can be measured using a transmission electron microscope or a scanning electron microscope. Specifically, the maximum length (Dmax) and the maximum vertical length (DV-max) of the island portion image derived from the incompatible resin are measured, and the geometric mean value (Dmax × DV-max) ^{1 / 2} can be the diameter of the island derived from the incompatible resin. The maximum length (Dmax) is the maximum length at two points on the contour of the island image, and the maximum vertical length (DV-max) sandwiches the island image between two straight lines parallel to the maximum length. This is the shortest length between these two straight lines. With this method, the diameter of the island part is measured for any 100 island parts, and the average value is taken as the diameter of the island part derived from the incompatible resin.

In the present invention, the b ^* value and haze value of the double-sided PSA sheet are also adjusted by using another PSA having a different composition, molecular weight, and glass transition temperature (Tg) from the main PSA composition. be able to. Examples of such resins include acrylic pressure-sensitive adhesive compositions, urethane-based pressure-sensitive adhesive compositions, polyester-based pressure-sensitive adhesive compositions, rubber-based pressure-sensitive adhesive compositions, and silicone-based pressure-sensitive adhesive compositions having different main compositions.

<Additives>
In addition to the above, the following additives may be added to the pressure-sensitive adhesive composition.

(I) Ultraviolet absorber The ultraviolet absorber can be selected from those having a maximum absorption wavelength in the ultraviolet region, and it is preferable to use an ultraviolet absorber having a maximum absorption wavelength at a wavelength of 350 nm or more. Examples of the ultraviolet absorber having a maximum absorption wavelength at a wavelength of 350 nm or longer include compounds represented by the following general formula (1) or (2).

In the above formula, R ¹ represents a hydrogen atom, a halogen atom, an alkoxy group having 1 to 4 carbon atoms, a nitro group or a cyano group, R ² represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ³ represents an alkyl group structure.

In the above formula, R ⁴ , R ⁵ and R ⁶ are a hydrogen atom, a hydroxyl group, an alkyl group structure or a halogen atom, and all of R ⁴ , R ⁵ and R ⁶ are not hydrogen atoms.

  The alkyl group structure is a concept including a substituent mainly composed of an alkyl group such as a substituted or unsubstituted alkyl group or a substituted or unsubstituted alkoxy group.

  Among them, an ultraviolet absorber that improves the compatibility by introducing an alkyl group having a large molecular weight into the aromatic ring of the basic skeleton and exhibits a liquid state or an oil state at 23 ° C. can be particularly preferably used. Here, being liquid or oily at 23 ° C. means a state in which there is fluidity only with an ultraviolet absorber even without a diluting solvent.

  It is preferable that content of the ultraviolet absorber in an adhesive composition is 0.5-8 mass parts with respect to 100 mass parts of solid content (especially base polymer) of an adhesive composition, and is 3-8 mass parts. More preferably, it is 4 to 6 parts by mass. The content of the ultraviolet absorber in the pressure-sensitive adhesive composition is preferably adjusted to such an amount that the ultraviolet transmittance at 380 nm is less than 5%.

(Ii) Other additives As an additive added to the pressure-sensitive adhesive composition, a light stabilizer typified by a hindered amine compound can be preferably exemplified. It is also preferable to use an antioxidant typified by a hindered phenol compound. Antioxidants are generally classified into primary antioxidants called radical chain terminators and secondary antioxidants that act as peroxide decomposers. Examples of the primary antioxidant include hindered phenol antioxidants, amine antioxidants, and lactone antioxidants. Examples of secondary antioxidants include phosphorus antioxidants and sulfur antioxidants.
These antioxidants may be used alone or in combination of two or more. In particular, when anti-corrosion effect of ITO is expected, it is preferable to use a primary antioxidant and a secondary antioxidant in combination because the effect can be easily obtained.

  The content of these additives is preferably 0.03 to 1.5 parts by mass and more preferably 0.05 to 1.0 parts by mass with respect to 100 parts by mass of the base polymer.

  The pressure-sensitive adhesive composition may contain additives other than the above, such as a silane coupling agent and a metal corrosion inhibitor, as necessary. Examples of the silane coupling agent include mercaptoalkoxysilane compounds (for example, mercapto group-substituted alkoxy oligomers). As the metal corrosion inhibitor, a type that prevents a corrosion by forming a complex with a metal and forming a film on the metal surface is preferable, and a benzotriazole-based metal corrosion inhibitor is particularly preferable.

(Double-sided adhesive sheet with release sheet)
The present invention also relates to a double-sided pressure-sensitive adhesive sheet with a release sheet in which a release sheet is laminated on at least one surface of the double-sided pressure-sensitive adhesive sheet described above. The release sheet is laminated on at least one surface of the double-sided pressure-sensitive adhesive sheet, and is preferably laminated on both surfaces of the double-sided pressure-sensitive adhesive sheet. Such a double-sided PSA sheet with a release sheet is obtained, for example, by applying a pressure-sensitive adhesive composition on a release sheet to form a coating film, and heating the coating film to obtain a cured product.

  The release sheet is a sheet having releasability on at least one side. Examples of the release sheet include a peelable laminate sheet having a release sheet substrate and a release agent layer provided on one side of the release sheet substrate, and a polyolefin film such as a polyethylene film and a polypropylene film as a low polarity substrate. It is done.

Papers and polymer films are used as the release sheet substrate in the peelable laminate sheet. As the release agent constituting the release agent layer, for example, a general-purpose addition type or condensation type silicone release agent or a long-chain alkyl group-containing compound is used. In particular, an addition type silicone release agent having high reactivity is preferably used.
Specific examples of silicone release agents include BY24-4527 and SD-7220 manufactured by Toray Dow Corning Silicone, KS-3600, KS-774, and X62-2600 manufactured by Shin-Etsu Chemical Co., Ltd. Is mentioned. Further, the silicone release agent may contain a silicone resin which is an organosilicon compound having a SiO ₂ unit and a (CH ₃ ) ₃ SiO _1/2 unit or CH ₂ ═CH (CH ₃ ) SiO _1/2 unit. preferable. Specific examples of the silicone resin include BY24-843, SD-7292, SHR-1404, etc. manufactured by Toray Dow Corning Silicone, KS-3800, X92-183, manufactured by Shin-Etsu Chemical Co., Ltd., and the like.

  In order for the release sheet to be easily peeled off, it is preferable that one release sheet and the other release sheet have different peelability. That is, when the peelability from one side and the peelability from the other are different, it becomes easy to peel only the release sheet having the higher peelability first. In that case, what is necessary is just to adjust the peelability of one peeling sheet and the other peeling sheet according to the bonding method and the bonding order.

When applying an adhesive composition on a peeling sheet, it can implement using a well-known coating apparatus. Examples of the coating apparatus include a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a micro gravure coater, a rod blade coater, a lip coater, a die coater, and a curtain coater.
The coating liquid contains a solvent. Examples of the solvent include methanol, ethanol, isopropanol, acetone, methyl ethyl ketone, toluene, n-hexane, n-butyl alcohol, methyl isobutyl ketone, methyl butyl ketone, ethyl butyl ketone, cyclohexanone, ethyl acetate, butyl acetate, propylene glycol monomethyl. Ether acetate, ethylene glycol monoethyl ether, propylene glycol monomethyl ether, N-methyl-2-pyrrolidone and the like are used. These may be used alone or in combination of two or more.
The coating film can be heated using a known heating device such as a heating furnace or an infrared lamp.

(Adhesive sheet with transparent substrate)
The present invention also relates to a pressure-sensitive adhesive sheet with a transparent substrate having the above-mentioned double-sided pressure-sensitive adhesive sheet and a transparent substrate layer. In the pressure-sensitive adhesive sheet with a transparent base material, a transparent base material layer is provided on one side of the double-sided pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer and the transparent base material layer of the double-sided pressure-sensitive adhesive sheet are laminated in contact with each other. Is preferred.

  The adhesive sheet with a transparent substrate may further have a hard coat layer. When the pressure-sensitive adhesive sheet with a transparent substrate further has a hard coat layer, it is preferable to provide an easy adhesion layer between the transparent substrate layer and the hard coat layer. Moreover, you may provide an easily bonding layer also between a double-sided adhesive sheet and a transparent base material layer as needed. FIG. 2 illustrates an embodiment of such a pressure-sensitive adhesive sheet with a transparent substrate. The pressure-sensitive adhesive sheet with a transparent substrate shown in FIG. 2 is a pressure-sensitive adhesive sheet with a transparent substrate having a hard coat layer, and includes a double-sided pressure-sensitive adhesive sheet 13, an easy-adhesion layer 11, a transparent base material layer 12, And the hard-coat layer 10 is laminated | stacked and comprised in this order.

[Transparent substrate layer]
A transparent base material layer functions as a base material which reinforces an adhesive sheet, or is utilized as a scattering prevention film of a conductive member using a glass base material, or a decorative film. Further, the transparent substrate layer may be a layer having optical characteristics (such as a retardation layer). That is, it may fulfill an optical function in addition to the function as a base material for reinforcing the diffusion adhesive layer.
A transparent base material layer is comprised from the transparent material which permeate | transmits visible light, For example, the film of transparent resin can be used suitably. Examples of transparent resin films include polyethylene terephthalate (PET) film, polyethylene naphthalate film, polypropylene terephthalate film, polybutylene terephthalate film, polypropylene naphthalate film, polyethylene film, polypropylene film, cellophane, diacetylcellulose film, and triacetyl. Cellulose film, acetylcellulose butyrate film, polyvinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, polymethylpentene film, polysulfone film, polyether ether ketone Film, polyethersulfone fill , Polyetherimide film, a polyimide film, a fluororesin film, a polyamide film, and acrylic resin film. Among these, a polyethylene terephthalate (PET) film is preferably used because of its excellent heat resistance.

  The transparent base material layer constituting the pressure-sensitive adhesive sheet with a transparent base material of the present invention may be a single layer or a plurality of layers. When comprised from a some layer, it is good also as a transparent base material layer being comprised from a different polyester-type resin.

The thickness of the transparent substrate layer constituting the pressure-sensitive adhesive sheet with a transparent substrate of the present invention is not particularly limited, but can be, for example, 10 μm or more, and can be selected within a range of 20 μm or more and 50 μm or more. . Although an upper limit changes with uses, it is also possible to select within the range of 1 cm or less, 1 mm or less, and 300 micrometers or less, for example.
The haze of the transparent substrate layer constituting the pressure-sensitive adhesive sheet with a transparent substrate of the present invention is preferably 5 or less, more preferably 3 or less, and even more preferably 1 or less.

[Hard coat layer]
A hard coat layer is a layer whose hardness is higher than a transparent base material layer, and has a function which prevents that the surface of an adhesive sheet with a transparent base material generate | occur | produces a damage | wound.
The hard coat layer preferably has a high hardness and transmits visible light. In the case of a general hard coat layer, the center line average roughness defined by JIS B 0601 is preferably 1 to 20 nm, and more preferably 10 nm or less. The center line average roughness can be measured using, for example, an ultra-deep shape measuring microscope manufactured by Keyence Corporation.
The hard coat layer may have anti-reflection, anti-glare and anti-watermark functions as necessary. Here, a watermark is a laminate of a touch panel module and a display device, and when there is a gap between them, the touch panel module and the display device are in contact with each other when the touch panel is operated, and the contacted part is wet with water. Say what you can see. In the case of a hard coat layer having such an antiglare function and an antiwatermark function, the center line average roughness defined by JIS B 0601 is preferably 20 to 500 nm, and more preferably 50 to 300 nm. The centerline average roughness can be measured using, for example, an ultra-deep shape measuring microscope manufactured by Keyence Corporation as described above.

  The hard coat layer preferably contains a hard component for imparting hardness. Examples of the hard component include a crosslinked polymer. Examples of the crosslinked polymer include a monofunctional monomer polymer and a polyfunctional monomer polymer. The polyfunctional monomer polymer is preferably a polymer of a polymerizable monomer containing a trifunctional or higher polyfunctional monomer, more preferably a polymer of a polymerizable monomer containing a tetrafunctional or higher polyfunctional monomer. For example, a copolymer of a mixed monomer of a trifunctional or higher polyfunctional monomer and a bifunctional monomer can be preferably exemplified. In addition, an oligomer is also contained in the monomer here.

Although the kind of monomer which can be used in order to obtain a crosslinked polymer is not specifically limited, For example, an acrylic monomer etc. can be illustrated preferably. For example, dipropylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyethylene glycol (mass average molecular weight 600) di (meth) acrylate, propylene oxide modified neo Bifunctional (meth) acrylates such as pentyl glycol di (meth) acrylate, modified bisphenol A di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, polyethylene glycol (mass average molecular weight 400) di (meth) acrylate, Pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane ethoxytri (meth) acrylate, polyether tri (meth) acrylate , Trifunctional (meth) acrylates such as glycerin propoxytri (meth) acrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol ethoxytetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, propionic acid modified dipenta Examples include tetra- or higher functional (meth) acrylates such as erythritol penta (meth) acrylate, dipentaerythritol monohydroxypenta (meth) acrylate, and dipentaerythritol hexa (meth) acrylate.
The monomer or oligomer of the organic compound having a polymerizable unsaturated group may be thermosetting or active energy ray curable.

  The hard coat layer may contain a flexible component. When the hard coat layer contains a flexible component, the occurrence of cracks and the like can be prevented. Examples of the flexible component include tricyclodecanemethylol di (meth) acrylate, ethylene oxide modified di (meth) acrylate of bisphenol F, ethylene oxide modified di (meth) acrylate of bisphenol A, ethylene oxide modified di (isocyanuric acid) Bifunctional (meth) acrylates such as (meth) acrylate, polypropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, propylene oxide modified tri (meth) acrylate of trimethylpropane, trimethyl Trifunctional (meth) acrylates such as propane ethylene oxide modified tri (meth) acrylate, urethane (meth) acrylate, polyester (meth) acrylate DOO, polyether (meth) acrylate.

  The hard coat layer may contain inorganic particles and / or organic particles. When inorganic particles and / or organic particles are contained, it is preferable in that curing shrinkage of the coating film is suppressed. Examples of the inorganic particles include inorganic oxide particles such as silicon dioxide particles, titanium dioxide particles, zirconium oxide particles, aluminum oxide particles, tin dioxide particles, antimony pentoxide particles, and antimony trioxide particles. Examples of the organic particles include resin particles such as acrylic resin, polystyrene, polysiloxane, melamine resin, benzoguanamine resin, polytetrafluoroethylene, cellulose acetate, polycarbonate, and polyamide.

  When inorganic particles are used, reactive inorganic oxide particles treated with a coupling agent may be used. When organic particles are used, reactive organic oxide particles treated with a coupling agent may be used. By treating with a coupling agent, the bonding strength with the acrylic polymer can be increased. As a result, surface hardness and scratch resistance can be improved, and dispersibility of inorganic oxide particles and organic particles can be improved.

  Examples of the coupling agent include γ-aminopropyltriethoxysilane, γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, and γ-mercaptopropyltrimethoxy. Examples thereof include silane, γ-aminopropyltriethoxysilane, and γ-aminopropyltriethoxyaluminum. These may be used individually by 1 type and may use 2 or more types together. The amount of the coupling agent to be treated is preferably 0.1 to 20 parts by mass and more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the inorganic oxide particles or the organic particles.

  The thickness of the hard coat layer is not particularly limited, but can be 0.5 μm or more, for example, and can be selected within a range of 1.0 μm or more and 2.0 μm or more. Although an upper limit changes with uses, it is also possible to select within the range of 100 micrometers or less, 50 micrometers or less, and 20 micrometers or less, for example.

[Easily adhesive layer]
An easy-adhesion layer is provided between a transparent base material layer and a hard-coat layer, for example, and has a function which adhere | attaches layers. Moreover, the easily bonding layer may be provided between the double-sided adhesive sheet and the transparent base material layer.

The easy adhesion layer preferably contains an acrylic resin or a polyester resin. Moreover, you may contain urethane type resin etc. as needed.
As acrylic resin used for an easily bonding layer, what is polymerized from an acrylic monomer as shown below is illustrated. For example, alkyl acrylate or alkyl methacrylate having a linear, branched or cyclic alkyl group, a hydroxy-containing monomer, an epoxy group-containing monomer, a monomer containing an amide group, etc., are not limited thereto. Absent. These monomer components may be copolymerized using two or more kinds.
Examples of the polyester resin include those that are polycondensed from a polybasic acid component and a polyol component. Examples of the polybasic acid used include terephthalic acid, isophthalic acid, and diphenylcarboxylic acid. Examples of the polyol component include, but are not limited to, ethylene glycol and diethylene glycol. These monomer components may be copolymerized using two or more kinds.
Examples of the urethane resin include those obtained as a reaction product of a polyol compound and an isocyanate compound. Examples of the polyol compound used include polyester polyol, polyether diol, and polyacetal diol. Examples of the isocyanate compound include tolylene diisocyanate and phenylene diisocyanate, but are not limited thereto. Moreover, these components can also be reacted using 2 or more types. Further, if necessary, a chain extender, a crosslinking agent and the like may be used.

  Particles can be added to the easy-adhesion layer for the purpose of imparting slipperiness and adjusting the refractive index. Examples of the particles include inorganic pigments and organic fillers, but it is preferable to use silica because the refractive index is relatively close to the resin of the easy-adhesion layer and high transparency can be obtained. Examples of the particles used for the purpose of adjusting the refractive index of the easy-adhesion layer include alumina-silica composite, titanium oxide, zirconium oxide, and zinc oxide, but are not limited thereto. Two or more kinds of these particles may be used.

  You may add various additives, such as an antistatic agent, a ultraviolet absorber, and a plasticizer, to an easily bonding layer as needed. In addition, a surfactant or a pH adjuster may be added for the purpose of improving coating suitability and reactivity.

  The thickness of the easy-adhesion layer is not particularly limited, but can be, for example, 0.1 nm or more, and can be selected within the range of 1 nm or more and 5 nm or more. Although an upper limit changes with uses, it is also possible to select within the range of 1 micrometer or less, 100 nm or less, and 50 nm or less, for example.

Although the formation method in particular of an easily bonding layer is not restrict | limited, When using polyester-type resin for a transparent base material layer, after melt | dissolving and extruding a polyester-type resin, it is preferable to form an easily-adhesive layer on a polyester-type resin sheet. . After the polyester resin sheet is melted and extruded, it is stretched 3 to 10 times in the longitudinal direction to form a longitudinally stretched polyester resin film, and subjected to corona discharge treatment as necessary. An easy-adhesion layer is applied to at least one surface and dried to form the easy-adhesion layer. Thereafter, the film having the easy-adhesion layer is stretched 3 to 10 times in the lateral direction to form the easy-adhesion layer stretched in the lateral direction simultaneously with the formation of the biaxially stretched polyester resin film.
Alternatively, the polyester resin and the easily adhesive layer resin may be extruded simultaneously to form a laminated film, and the laminated film may be biaxially stretched 9 to 100 times by a known method to form an easily adhesive layer. good.
Further, when laminating the pressure-sensitive adhesive layer or the hard coat layer, surface treatment may be performed by a known method such as corona discharge treatment or flame treatment, if necessary.

[Peeling sheet]
The pressure-sensitive adhesive sheet with a transparent substrate of the present invention may have a release sheet on the opposite side of the double-sided pressure-sensitive adhesive sheet on which the transparent substrate layer or the hard coat layer is formed. As the release sheet, the release sheet described above can be exemplified.

  It is preferable that the adhesive sheet with a transparent base material comprised as mentioned above is used for bonding of the electrically-conductive member in which the electroconductive part was provided in a part on a transparent support body. When such an adhesive sheet with a transparent substrate is applied to a conductive member, it adheres to the conductive part side of the conductive member with sufficient adhesive force, and makes the conductive part pattern invisible, thereby suppressing the occurrence of sparkling. Can do.

(Optical member)
The optical member of the present invention has a configuration in which the double-sided pressure-sensitive adhesive sheet of the present invention is bonded to at least a conductive member provided with a conductive portion on a part of a transparent support. Moreover, the optical member of the present invention may be configured by bonding the pressure-sensitive adhesive sheet with a transparent substrate of the present invention to a conductive member having a conductive part provided on a part of the transparent support. . That is, in the optical member of the present invention, the double-sided pressure-sensitive adhesive sheet of the present invention is bonded to a conductive member provided with a conductive portion on a part of the transparent support, and further on the side opposite to the conductive member of the double-sided pressure-sensitive adhesive sheet. In addition, at least one of a transparent substrate layer and a hard coat layer may be provided. Furthermore, an easy-adhesion layer may be provided between the double-sided PSA sheet and the transparent substrate layer or the hard coat layer, and between the transparent substrate layer and the hard coat layer. FIG. 3 illustrates such an aspect of the optical member. The optical member shown in FIG. 3 is configured by laminating a conductive member 15, a double-sided pressure-sensitive adhesive sheet 13, an easy adhesion layer 11, a transparent base material layer 12, an easy adhesion layer 11, and a hard coat layer 10 in this order. .

[Transparent support]
The conductive member has a transparent support and a conductive portion. As the transparent support for the conductive member, any support made of a transparent material, which is usually used for optical members such as glass, can be used. If this invention is applied, even if the transparent support body which consists of glass, for example is damaged, scattering of glass will be suppressed with a double-sided adhesive sheet, and the safety | security of a product can be improved.

[Conductive part]
The conductive part is a layer made of a conductive material, and is formed on the transparent support in a pattern according to the use of the conductive member.
For example, when the optical member is applied to a surface capacitive touch panel or the like, the conductive portion is a pattern corresponding to a uniform layer having substantially uniform conductive performance in the in-plane direction and a lead electrode or the like. And having an electrode layer formed around the electrode layer. Further, when this optical member is applied to a projected capacitive touch panel, the conductive portion is formed as a conductive layer in which the conductive performance is regularly patterned. In this projected capacitive touch panel, the surface of the transparent support on which no conductive part is formed functions as a non-conductive part for position detection. Note that a protective film for preventing oxidation of the conductive film may be further formed over the conductive portion.

The conductive performance of the conductive layer can be shown by, for example, the surface resistance measured by the method described in JIS-K7194. In order to obtain an electrode plate for a touch panel, the surface resistance is 1 × 10 ⁵ Ω / sq or less. Is preferably 1 × 10 ³ Ω / sq or less. The surface resistance is preferably 0.1 Ω / sq or more. The range of the surface resistance of the conductive layer is preferably 0.1 to 1 × 10 ⁵ Ω / sq, more preferably 0.1 to 1 × 10 ³ Ω / sq.
On the other hand, the non-conductive part has a surface resistance measured by, for example, a method described in JIS-K6911 of 1 × 10 ⁹ Ω / sq or more, more preferably 1 × 10, in order for the touch panel to perform more accurate position detection. ¹¹ Ω / sq or more and 1 × 10 ¹³ Ω / sq or less, more preferably 1 × 10 ¹² Ω / sq or less, and it is better to be clearly insulated. The range of the surface resistance of the non-conductive portion is preferably 1 × 10 ⁹ to 1 × 10 ¹³ Ω / sq, and more preferably 1 × 10 ¹¹ to 1 × 10 ¹² Ω / sq.

A known conductive substance can be applied as the material of the conductive portion. As the conductive substance, an inorganic material may be used. Examples of the inorganic material include metals such as gold, silver, copper, aluminum, nickel, and cobalt, or indium tin oxide (Indium Tin Oxide ( ITO)), indium-zinc oxide (IZO), zinc oxide (Zinc Oxide (ZnO)), zinc-tin oxide (Zinc Tin Oxide (ZTO)), or antimony-tin oxide ( ATO) and the like can be exemplified. An organic conductor may be used as the conductive substance, and examples of the organic conductor include conductive carbon materials such as conductive carbon nanotubes and graphene, or conductive polymers such as polythiophene or polyaniline, It is not limited to these.
Among them, ITO is most preferably used as an inorganic material because it is highly reliable and has excellent transparency and conductivity. In addition, PEDOT / PSS, which is a kind of organic conductive polymer polythiophene, is also suitably used because it has the characteristics of excellent flexibility and the characteristics of transparency and conductivity. PEDOT / PSS indicates a polymer complex in which PEDOT (polymer of 3,4-ethylenedioxythiophene) and PSS (polymer of styrene sulfonic acid) coexist.
Metals and conductive carbon materials are inferior in transparency compared to conductive materials that are relatively excellent in transparency, such as ITO and PEDOT / PSS. It is good to ensure transparency by processing into a mesh shape. Among these, silver is preferably used because it is a conductive material having the highest conductivity.

  The thickness of the conductive part needs to be set in consideration of the conductivity, transparency, etc. of the applied conductor, so the thickness is not particularly limited. For example, in the case of a metal system, a thickness of 30 to 600 mm, a metal oxide system In the case of organic type, a thickness of 80 to 5000 mm is preferable.

The conductive portion can be formed by a known method. Specifically, the conductive portion may be formed by a method in which a conductive layer is partially provided on a transparent substrate by various printing methods or the like, and after forming a uniform conductive layer, a part thereof is etched or the like. The conductive portion may be formed by removing the conductive portion. Methods for forming a uniform conductive layer include thin film formation methods such as vacuum deposition, sputtering, ion plating, spray pyrolysis, chemical plating, electroplating, coating, or a combination thereof. Can be mentioned. From the viewpoints of film formation speed, large area film formability, and productivity, vacuum deposition and sputtering are preferred.
Prior to the formation of the conductive portion, the surface of the transparent support may be subjected to appropriate pretreatment such as corona discharge treatment, ultraviolet irradiation treatment, plasma treatment, sputter etching treatment, or undercoat treatment in order to enhance adhesion. good.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

Example 1
0.1 parts by mass of a crosslinking agent (manufactured by Tosoh Corporation: Coronate L55E) and 100 parts by mass of light diffusing particles (Soken) A pressure-sensitive adhesive composition was obtained by adding 7 parts by mass of Chemisor Corporation: Chemisnow KMR-3TA) and stirring with a planetary stirrer until the particles were uniformly dispersed.
This pressure-sensitive adhesive composition was applied to the surface of the release agent layer of the first release sheet (Mitsubishi Resin Co., Ltd .: MRV # 50) with an applicator and dried at 100 ° C. for 2 minutes to give a pressure-sensitive adhesive layer (double-sided pressure-sensitive adhesive). Sheet). Next, the release agent layer side of the second release sheet (manufactured by Mitsubishi Plastics Co., Ltd .: MRE # 38) was overlaid on the adhesive layer and pasted with a laminator. As a result, a double-sided PSA sheet having a first release sheet and a second release sheet was obtained. The thickness of the adhesive layer after drying was 25 μm.

(Example 2)
A double-sided PSA sheet having a thickness after drying of 25 μm was obtained in the same manner as in Example 1 except that the addition amount of the light diffusing particles was changed to 14 parts by mass.

(Example 3)
A double-sided PSA sheet having a thickness of 25 μm after drying was obtained in the same manner as in Example 1 except that the addition amount of the light diffusing particles was 21 parts by mass.

Example 4
The acrylic polymer was changed to Nisset TN5961 manufactured by Nippon Carbide Industries Co., Ltd., in the same manner as in Example 1 except that the amount of the crosslinking agent was 0.2 parts by mass and the amount of the light diffusing particles added was 10 parts by mass. A double-sided PSA sheet having a thickness of 25 μm was obtained.

(Example 11)
0.08 parts by mass of a cross-linking agent (manufactured by Tosoh Corp .: Coronate L55E) with respect to 100 parts by mass of the solid content of the acrylic polymer solution (manufactured by Nippon Synthetic Chemical Industry Co., Ltd .: Coponil N-9277) Toagosei Co., Ltd .: ARUFON UH2170) was added in an amount of 10 parts by mass and stirred using a stirrer. The pressure-sensitive adhesive composition was obtained by stirring until the incompatible resin was uniformly dispersed in the solvent in the acrylic polymerization solution.
This pressure-sensitive adhesive composition was applied to the surface of the release agent layer of the first release sheet (Mitsubishi Resin Co., Ltd .: MRV # 50) with an applicator and dried at 100 ° C. for 2 minutes to give a pressure-sensitive adhesive layer (double-sided pressure-sensitive adhesive). Sheet). Next, the release agent layer side of the second release sheet (manufactured by Mitsubishi Plastics Co., Ltd .: MRE # 38) was overlaid on the adhesive layer and pasted with a laminator. As a result, a double-sided PSA sheet having a first release sheet and a second release sheet was obtained. The thickness of the adhesive layer after drying was 25 μm.

(Example 12)
A double-sided PSA sheet having a dried thickness of 25 μm was obtained in the same manner as in Example 11 except that the amount of the incompatible resin added was 15 parts by mass.

(Example 13)
A double-sided PSA sheet having a thickness after drying of 25 μm was obtained in the same manner as in Example 11 except that the addition amount of the incompatible resin was 20 parts by mass.

(Example 14)
A double-sided PSA sheet having a thickness of 25 μm after drying was obtained in the same manner as in Example 11 except that the incompatible resin was changed to “Clearon K100” manufactured by Yasuhara Chemical Co., Ltd. and the addition amount was changed to 5 parts by mass.

(Example 15)
A double-sided PSA sheet having a thickness after drying of 25 μm was obtained in the same manner as in Example 14 except that the addition amount of the incompatible resin was 10 parts by mass.

(Example 16)
A double-sided PSA sheet having a thickness after drying of 25 μm was obtained in the same manner as in Example 14 except that the amount of the incompatible resin added was 15 parts by mass.

(Example 17)
A double-sided PSA sheet having a thickness after drying of 25 μm was obtained in the same manner as in Example 14 except that the incompatible resin was changed to “Clearon P150” manufactured by Yasuhara Chemical Co., Ltd.

(Example 18)
A double-sided PSA sheet was obtained in the same manner as in Example 17 except that the coating amount was adjusted so that the thickness after drying was 50 μm.

(Comparative Example 1)
Change the acrylic polymer to Syavine BPS6377-OP made by Toyo Ink Co., change the amount of cross-linking agent to 0.5 parts by mass, change the light diffusing particles to “MX500” made by Soken Chemical Co., Ltd., and change the amount of light diffusing particles added A double-sided PSA sheet having a thickness of 25 μm after drying was obtained in the same manner as in Example 1 except that the amount was 8.5 parts by mass.

(Comparative Example 2)
Both surfaces with a thickness of 25 μm after drying were the same as Comparative Example 1 except that the light diffusing particles were changed to “Art Pearl JB-800T” manufactured by Negami Kogyo Co., Ltd., and the amount of the light diffusing particles added was 17 parts by mass. An adhesive sheet was obtained.

(Comparative Example 3)
A double-sided pressure-sensitive adhesive sheet having a thickness of 25 μm after drying was obtained in the same manner as in Comparative Example 2 except that the addition amount of the light diffusing particles was 26 parts by mass.

(Comparative Example 4)
A double-sided pressure-sensitive adhesive sheet having a thickness of 25 μm after drying was obtained in the same manner as in Comparative Example 1 except that the light diffusing particles were changed to “Chemisnow MX1000” manufactured by Soken Chemical Co., Ltd. and the addition amount of the light diffusing particles was changed to 12 parts by mass. Obtained.

(Comparative Example 5)
A double-sided PSA sheet having a thickness after drying of 25 μm was obtained in the same manner as in Comparative Example 4 except that the addition amount of the light diffusing particles was 25 parts by mass.

(Comparative Example 6)
A double-sided PSA sheet having a thickness of 25 μm after drying was obtained in the same manner as in Comparative Example 4 except that the amount of light diffusing particles added was 35 parts by mass.

(Comparative Example 7)
The acrylic polymer and the cross-linking agent were changed to SK Dyne 2094 and E-AX, respectively, manufactured by Soken Chemical Co., Ltd., the addition amount of the cross-linking agent was 0.1 parts by mass, and the light diffusing particles were “Techpolymer SBX” manufactured by Sekisui Chemical. The double-sided PSA sheet having a thickness after drying of 25 μm was obtained in the same manner as in Example 1 except that the amount was changed to “−8” and the addition amount of the light diffusing particles was changed to 1 part by mass.

(Comparative Example 8)
A double-sided PSA sheet having a thickness after drying of 25 μm was obtained in the same manner as in Example 11 except that the amount of the incompatible resin added was 6 parts by mass.

(Evaluation)
(Haze)
Paste one adhesive surface of each double-sided adhesive sheet of each example and each comparative example to a slide glass (product number: S9112) manufactured by Matsunami Glass Co., Ltd., and paste a transparent PET film (CPET75H, New Tac Kasei Co., Ltd.) on the other adhesive surface. Combined. Subsequently, in order to eliminate the influence of fine air mixed at the time of bonding, the laminated samples were subjected to an autoclave (pressure defoaming) treatment for 30 minutes under the conditions of 0.5 MPa and 40 ° C. The haze of these bonded products was measured using NDH4000 manufactured by Nippon Denshoku Industries Co., Ltd.

(B ^* value)
<Measurement method of transmission b _T ^* >
Using the spectral color difference meter “Spectro Color Meter SE2000” manufactured by Nippon Denshoku Industries Co., Ltd., the laminate sample used for the above haze measurement is set so that the PET side becomes the light source side, and in the transmission measurement mode, b ^* Measured value.
<Method of measuring reflection b _R ^* haze>
The same laminate sample was set so that the PET side was the light source side using a spectrocolor difference meter “Spectro Color Meter SE2000” manufactured by Nippon Denshoku Industries Co., Ltd. A black patch was set and b ^* value was measured in the reflection measurement mode.

(Measuring method of φ)
<Measurement of average particle diameter of fine particles>
The average particle diameter (primary particle diameter) of the fine particles (light diffusing particles) was measured using a transmission electron microscope or a scanning electron microscope. Specifically, the maximum length (Dmax) and maximum length vertical length (DV-max) of the particle image of the fine particles were measured, and the geometric mean value (Dmax × DV-max) ^1/2 was taken as the particle diameter. . The maximum length (Dmax) is the maximum length at two points on the contour of the particle image, and the maximum vertical length (DV-max) is when the particle image is sandwiched between two straight lines parallel to the maximum length. The shortest length between these two straight lines. With this method, the particle diameter of 100 arbitrary fine particles was measured, and the average value was taken as the average particle diameter of the fine particles.

<Measurement of island diameter derived from incompatible resin>
The diameter of the island part derived from the incompatible resin was measured using a transmission electron microscope or a scanning electron microscope. Specifically, the maximum length (Dmax) and the maximum vertical length (DV-max) of the island portion image derived from the incompatible resin are measured, and the geometric mean value (Dmax × DV-max) ^{1 / 2} was the diameter of the island derived from the incompatible resin. The maximum length (Dmax) is the maximum length at two points on the contour of the island image, and the maximum vertical length (DV-max) sandwiches the island image between two straight lines parallel to the maximum length. In this case, the shortest length between these two straight lines was used. With this method, the diameter of the island part was measured for any 100 island parts, and the average value was taken as the diameter of the island part derived from the incompatible resin.

(Pattern erase effect)
An electrode member having an ITO pattern formed on a transparent support was prepared, and the double-sided PSA sheet prepared in each Example and each Comparative Example was bonded to this electrode member so as to be in contact with the ITO pattern. And it was observed visually whether the ITO pattern was visible from the transparent support body side of an electrode member, and it evaluated according to the following references | standards. △ Evaluation or higher was regarded as an acceptable level.
◎: The ITO pattern is not visually recognized at all ○: The ITO pattern is almost invisible △: The ITO pattern is visually recognized but allowed level ×: The ITO pattern is clearly visible

(Sparkling evaluation)
The screen was set so that the entire Xperia SO-01 display was white, and the double-sided PSA sheet prepared in each Example and each Comparative Example was placed thereon, and sparkling (screen glare) was visually evaluated. A B rating or higher was regarded as an acceptable level.
A: No sparkling is visible B: Sparkling is almost invisible C: Sparkling is somewhat visible D: Sparkling is clearly visible

  As shown in Table 1, in the double-sided pressure-sensitive adhesive sheets of the examples, the ITO pattern was invisible and the occurrence of sparkling was suppressed. On the other hand, in the double-sided pressure-sensitive adhesive sheet of the comparative example, sparkling occurred or the ITO pattern was not sufficiently invisible.

DESCRIPTION OF SYMBOLS 10 Hard coat layer 11 Easy-adhesion layer 12 Transparent base material layer 13 Double-sided adhesive sheet 14 Intermediate support layer 15 Conductive member 20 Adhesive layer

Claims (5)

The double-sided pressure-sensitive adhesive sheet satisfies the condition of the following formula (1) and has a haze value of 5% or more ,
The double-sided pressure-sensitive adhesive sheet contains a base polymer containing an acrylic copolymer and an incompatible resin in an amount of 1 to 50% by mass based on the total mass of the base polymer,
The incompatible resin is at least one selected from a tackifier and a styrene copolymer resin,
In the base polymer, the incompatible resin is scattered in an island shape,
Double-sided adhesive sheet;
4.0 <(Δb ^* × 100) / (Hz × φ) <300 Formula (1)
In the formula (1), Δb ^* = b _T ^* −b _R ^* , b _T ^* represents the b ^* value of the double-sided pressure-sensitive adhesive sheet measured with transmitted light, and b _R ^* is the double-sided pressure-sensitive adhesive sheet measured with reflected light. represents the b ^* value, Hz represents the haze value of the double-sided pressure-sensitive adhesive sheet, phi represents the diameter of the island portion from a non-compatible resin. The double-sided pressure-sensitive adhesive sheet according to claim 1 , wherein the double-sided pressure-sensitive adhesive sheet is used for bonding a conductive member having a conductive part provided on a part of a transparent support. Claim 1 or 2 double-sided pressure-sensitive adhesive sheet of at least one of the release-sheet laminated double-sided PSA sheet release sheet is laminated on a surface according to. The adhesive sheet with a transparent base material which has a double-sided adhesive sheet of Claim 1 or 2 , and a transparent base material layer. The optical member which has a double-sided adhesive sheet of Claim 1 or 2 , and the electrically-conductive member in which the electroconductive part was provided in a part on a transparent support body.

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