JP5796126B2 - Optical pressure-sensitive adhesive composition, optical pressure-sensitive adhesive sheet, image display device and input / output device - Google Patents

Description

  The present invention relates to an optical pressure-sensitive adhesive composition, an optical pressure-sensitive adhesive sheet, an image display device, and an input / output device.

  In recent years, an image display device such as a liquid crystal display device and an input / output device such as a touch panel used in combination with the image display device have been widely used. In the production of these image display devices and input / output devices, an adhesive composition is used when the constituent members are bonded together.

  Along with the miniaturization of electronic components constituting these image display devices and input / output devices, for example, high-frequency noise generated in a circuit, or charging of a dielectric sandwiched between conductors during driving, A malfunction caused by noise generated in an internal circuit included in a component cannot be ignored. In particular, some of the pressure-sensitive adhesive layers formed from a pressure-sensitive adhesive composition mainly composed of an acrylic pressure-sensitive adhesive have a dielectric constant exceeding 4, and a pressure-sensitive adhesive composition having such a relative dielectric constant was used. In this case, the capacitance as the insulating layer is high, and malfunction due to high frequency noise may occur.

  For example, Patent Document 1 discloses an optical pressure-sensitive adhesive sheet intended to prevent malfunction of a capacitive touch panel input / output device.

International Publication WO2010 / 147047

  The present inventors diligently prevent the malfunction of the image display device and the input / output device by reducing the relative dielectric constant of the pressure-sensitive adhesive composition used in the manufacture of the image display device and the input / output device. As a result of the investigation, it was found that the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition containing a specific material has a low relative dielectric constant and excellent durability, adhesion and weather resistance.

  The present invention is an optical pressure-sensitive adhesive composition capable of obtaining a pressure-sensitive adhesive layer having a reduced dielectric constant and excellent durability, adhesion, and weather resistance, and formed using the optical pressure-sensitive adhesive composition Provided are an optical display sheet and an input / output device including the optical pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer formed using the optical pressure-sensitive adhesive composition.

1. The optical pressure-sensitive adhesive composition according to one aspect of the present invention is
(A) a hydrogenated block copolymer;
(B) a first compatibilizer;
(C) a second compatibilizer, comprising an optical pressure-sensitive adhesive composition,
The (A) hydrogenated block copolymer has a hard segment composed of a polymer component of an aromatic vinyl monomer and a soft segment composed of a polymer component of a conjugated diene monomer,
The (B) first compatibilizer has a property compatible with the hard segment, and has a softening point of 80 ° C. or higher,
The (C) second compatibilizer has a property compatible with the soft segment and is liquid at room temperature (23 ° C.).
The pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition has a relative dielectric constant of 1 or more and 3.5 or less.

  2. In the optical pressure-sensitive adhesive composition according to the above 1, the content of the hard segment in the (A) hydrogenated block copolymer may be 5% by mass or more and 70% by mass or less.

  3. 3. The optical pressure-sensitive adhesive composition as described in 1 or 2 above, wherein the hydrogenation rate of the double bond contained in the polymer component of the conjugated diene monomer constituting the hydrogenated block copolymer (A) is 90%. That can be the end.

  4). 4. The optical pressure-sensitive adhesive composition as described in any one of 1 to 3 above, wherein the (B) first compatibilizer may be an aromatic tackifying resin.

  5. 5. The optical pressure-sensitive adhesive composition as described in 4 above, wherein the aromatic tackifying resin is an aromatic petroleum resin, a styrene polymer, an α-methylstyrene polymer, or a styrene- (α-methylstyrene) copolymer. At least selected from the group consisting of a polymer, a styrene-aliphatic hydrocarbon copolymer, a styrene- (α-methylstyrene) -aliphatic hydrocarbon copolymer, and a styrene-aromatic hydrocarbon copolymer. It can be one kind.

  6). 6. The optical pressure-sensitive adhesive composition according to any one of 1 to 5, wherein (C) the second compatibilizer is at least selected from the group consisting of a polybutene compound, a polyisobutylene compound, and a polyisoprene compound. It can be one kind.

  7). 7. The optical pressure-sensitive adhesive composition according to any one of 1 to 6 above, wherein an acid value of the optical pressure-sensitive adhesive composition can be 1 or less.

  8). 8. The optical pressure-sensitive adhesive composition according to any one of 1 to 7 above, wherein the content of the (B) first compatibilizer is 5 masses per 100 mass parts of the (A) hydrogenated block copolymer. Part to 60 parts by mass.

  9. 9. The optical pressure-sensitive adhesive composition according to any one of 1 to 8 above, wherein the content of the (C) second compatibilizer is 5 masses per 100 mass parts of the (A) hydrogenated block copolymer. Part to 60 parts by mass.

  10. 10. The optical pressure-sensitive adhesive composition according to any one of 1 to 9 above, wherein the total content of the (B) first compatibilizer and the (C) second compatibilizer is the (A) hydrogenated block. It can be 10 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the copolymer.

  11. The optical pressure-sensitive adhesive composition according to any one of 1 to 10 above, further comprising (D) a third compatibilizer that is compatible with the soft segment and is solid at room temperature (23 ° C.), (D) The third compatibilizer can be a rosin-based tackifier resin, a terpene-based tackifier resin, or a hydrogenated alicyclic hydrocarbon resin.

12 12. The optical pressure-sensitive adhesive composition according to any one of 1 to 11, wherein the pressure-sensitive adhesive layer has a relative dielectric constant at a frequency of 1.0 × 10 ⁶ Hz and a ratio at a frequency of 1.0 × 10 ² Hz. It can be 90% or more of the dielectric constant.

  13. The optical pressure-sensitive adhesive composition according to any one of 1 to 12 above, can be used for bonding members constituting a touch panel type input / output device.

  14 The pressure-sensitive adhesive sheet according to another aspect of the present invention is obtained by applying the optical pressure-sensitive adhesive composition according to any one of 1 to 13 above to the surface of a separator and drying it.

  15. The image display apparatus which concerns on another one aspect | mode of this invention contains the adhesive layer formed using the optical adhesive composition in any one of said 1 thru | or 13.

  16. The input / output device which concerns on another one aspect | mode of this invention contains the adhesive layer formed using the optical adhesive composition in any one of said 1 thru | or 13.

  When the optical pressure-sensitive adhesive composition contains the component (A), the component (B), and the component (C), the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition has a relative dielectric constant of 1 or more and 3. Therefore, malfunction caused by noise generated in an internal circuit included in the display device and malfunction caused by charging of a dielectric sandwiched between conductors can be prevented, and durability, adhesion and An adhesive layer having excellent weather resistance can be obtained. The image display device and the input / output device using the optical pressure-sensitive adhesive composition have a pressure-sensitive adhesive layer excellent in durability, adhesion, and weather resistance, and malfunction due to noise generated in the internal circuit. Can be prevented.

FIG. 1 schematically shows the relationship between the relative dielectric constant and frequency of the pressure-sensitive adhesive layer formed from the component (A) (hydrogenated block copolymer) constituting the pressure-sensitive adhesive composition according to Example 1 of the present invention. FIG. FIG. 2 is a cross-sectional view schematically showing a configuration of an input / output device (touch panel type input / output device) according to an embodiment of the present invention. FIG. 3 is a cross-sectional view schematically showing a configuration of a known input / output device (touch panel type input / output device).

  Hereinafter, the present invention will be described in detail with reference to the drawings. In the present invention, “parts” means “parts by mass” and “%” means “mass%” unless otherwise specified.

1. Optical pressure-sensitive adhesive composition The optical pressure-sensitive adhesive composition according to an embodiment of the present invention (hereinafter, sometimes simply referred to as “pressure-sensitive adhesive composition”) is obtained from (A) hydrogenated block copolymer ( Hereinafter, it may be simply referred to as “component (A)”), (B) a first compatibilizer (hereinafter sometimes simply referred to as “component (B)”), and (C). A second compatibilizer (hereinafter sometimes simply referred to as “component (C)”). The relative dielectric constant of the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition according to this embodiment is 1 or more and 3.5 or less.

1.1. (A) Component (A) The hydrogenated block copolymer (H) is a hard segment composed of a polymer component of an aromatic vinyl monomer and a polymer of a conjugated diene monomer. It is a thermoplastic elastomer having a soft segment composed of components. More specifically, the aromatic vinyl compound is preferably styrene or α-methylstyrene (more preferably styrene), and the conjugated diene compound is preferably butadiene or isoprene.

  The pressure-sensitive adhesive layer formed using the pressure-sensitive adhesive composition according to this embodiment containing the component (A) has a relative dielectric constant as compared with the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition containing an acrylic polymer. Is low (for example, the relative dielectric constant is 1 or more and 3.5 or less).

  Specific examples of the component (A) include, for example, styrene- (ethylene-propylene) -styrene type block copolymer (SEPS) (hydrogenated product of styrene-isoprene-styrene type block copolymer (SIS)), styrene. -(Butadiene-butylene) -styrene type block copolymer (SBBS) hydrogenated product, styrene- (ethylene-butylene) -styrene type block copolymer (SEBS) (styrene-butadiene-styrene type block copolymer ( Hydrogenated product of SBS), styrene- (ethylene-propylene) type block copolymer (SEP) (hydrogenated product of styrene-isoprene type block copolymer (SI)), styrene- (ethylene-butylene) type block Copolymer (SEB) (hydrogenation of styrene-butadiene block copolymer (SB) ), And the like. Among these, from the viewpoint of excellent compatibility with the component (B), the component (A) is composed of styrene- (ethylene-propylene) -styrene type block copolymer (SEPS), styrene- (ethylene-butylene)- ABA type hydrogenated block copolymers such as styrene type block copolymers (SEBS) are particularly preferred. These may be used singly or in combination of two or more.

  In the present invention, “compatible” or “compatibilizing” means that turbidity or phase separation is not visually confirmed in a mixture obtained by mixing two different components. .

  Here, whether the component (B) is compatible with the hard segment constituting the component (A) is synthesized only from the component corresponding to the hard segment of the component (A), that is, the aromatic vinyl monomer. The polymer to be evaluated and the component (B) are evaluated.

  More specifically, turbidity occurs in a mixture obtained by mixing a polymer polymerized only from an aromatic vinyl monomer and the component (B) using a solvent, if necessary, or the weight. In the case where phase separation between the phase containing the coalescence and the phase containing the component (B) is not observed visually, the component (B) shall be compatible with the hard segment constituting the component (A), When the above-described turbidity or phase separation is visually observed, the component (B) is not compatible with the hard segment constituting the component (A).

  As the component (A), commercially available hydrogenated block copolymers such as SEP type septons 1001 and 1020, SEPS type septons 2002, 2004, 2005, 2006, 2007, 2063 and 2104, SEBS type septon 8004, 8006, 8007, 8076 and 8104 (all of the above Septon series are manufactured by Kuraray Co., Ltd.), SEBS type Tuftec H1221, H1662, H1052, H1053, H1041, H1051, H1517, H1043, H1272 and N504, SBBS type Tuftec P1500, P2000 and JT83X (all of the above Tuftec series are manufactured by Asahi Kasei Corporation) can also be used.

  From the viewpoint of imparting heat resistance to the pressure-sensitive adhesive composition according to this embodiment, the content of the hard segment (for example, styrene) in the component (A) is preferably 5% by mass or more and 70% by mass or less, and 10% by mass. More preferably, it is 60 mass% or less. When the content of the hard segment in the component (A) is less than 5% by mass, the heat resistance is inferior. On the other hand, when the content exceeds 70% by mass, the pressure-sensitive adhesive layer becomes too hard and the adhesion to the adherend is inferior. There is.

  From the viewpoint of excellent compatibility with the component (C), the hydrogenation rate (hydrogenation rate) of double bonds contained in the polymer component of the conjugated diene monomer constituting the component (A) , Simply referred to as “hydrogenation rate”) is preferably 90% or more, and more preferably 95% or more (note that the hydrogenation rate is preferably 100%, but the trace amount is 2%). It does not matter if a heavy bond remains). That is, in the present invention, the hydrogenation rate of the double bond contained in the polymer component of the conjugated diene monomer is saturated by hydrogenation among the double bonds contained in the polymer component of the conjugated diene monomer. The ratio of what is being done.

  Here, whether the component (C) is compatible with the soft segment constituting the component (A) is synthesized only from the component corresponding to the soft segment of the component (A), that is, the conjugated diene monomer. Evaluation will be made using the polymer and the component (B).

  More specifically, the occurrence of turbidity in the mixture obtained by mixing the polymer polymerized only from the conjugated diene monomer and the component (C) using a solvent as necessary, or When the occurrence of phase separation is not visually observed between the phase containing and the phase containing component (C), component (C) shall be compatible with the soft segment constituting component (A). On the other hand, when the above-mentioned turbidity or phase separation is visually observed, the component (C) is not compatible with the soft segment constituting the component (A).

  Furthermore, from the viewpoint of preventing corrosion of the adherend, the acid value of the pressure-sensitive adhesive composition according to this embodiment is preferably 1 or less.

  The content of the component (A) in the pressure-sensitive adhesive composition according to this embodiment is preferably 50% by mass or more and 90% by mass or less, and more preferably 55% by mass or more and 80% by mass or less.

1.2. (B) Component The 1st compatibilizer which is (B) component has a property compatible with the hard segment which comprises (A) component, and a softening point (softening point) is 80 degreeC or more. Since the pressure-sensitive adhesive composition according to the present embodiment contains the component (B), the component (B) is compatible with the hard segment constituting the component (A), and thus the pressure-sensitive adhesive formed from the pressure-sensitive adhesive composition. While giving a certain degree of hardness to the layer, the adhesion to the adherend can be enhanced, and the heat resistance of the pressure-sensitive adhesive layer can be enhanced.

  The component (B) can be, for example, an aromatic tackifier resin. The aromatic tackifying resin used as the component (B) preferably has a molecular weight of 5,000 or less from the viewpoint of compatibility. Examples of aromatic tackifying resins that can be used as the component (B) include aromatic petroleum resins, styrene polymers, α-methylstyrene polymers, styrene- (α-methylstyrene) copolymers, Examples thereof include styrene-aliphatic hydrocarbon copolymers, styrene- (α-methylstyrene) -aliphatic hydrocarbon copolymers, styrene-aromatic hydrocarbon copolymers, and the like. More specifically, for example, FMR-0150 (softening point 145 ° C., manufactured by Mitsui Chemicals) as a commercially available styrene-aromatic hydrocarbon copolymer, FTR- as a styrene-aliphatic hydrocarbon copolymer. 6100 (softening point 100 ° C., Mitsui Chemicals), FTR-6110 (softening point 110 ° C., Mitsui Chemicals) and FTR-6125 (softening point 125 ° C., Mitsui Chemicals), styrene (α-methylstyrene) ) -FTR-7100 as an aliphatic hydrocarbon copolymer (softening point 100 ° C., Mitsui Chemicals), FTR-8120 as a styrene polymer (softening point 120 ° C., Mitsui Chemicals) and SX- 100 (softening point 100 ° C., manufactured by Yasuhara Chemical Co., Ltd.), FTR-0100 (softening point 100 ° C., manufactured by Mitsui Chemicals) as an α-methylstyrene-based polymer, styrene (α-methyl) Styrene copolymer FTR-2120 (softening point 120 ° C., Mitsui Chemicals), FTR-2140 (softening point 145 ° C., Mitsui Chemicals), Crystallex 3100 (softening point 100 ° C., Eastman Chemical) ), Crystallex 3085 (softening point 85 ° C., Eastman Chemical), Crystallex 5140 (softening point 140 ° C., Eastman Chemical), Crystallex 1120 (softening point 120 ° C., Eastman Chemical) ), Crystallex F85 (softening point 85 ° C., Eastman Chemical Co.), Crystallex F100 (softening point 100 ° C., Eastman Chemical Co.) and Crystallex F115 (softening point 115 ° C., Eastman Chemical Co.), Etc. can also be used.

  The softening point of the component (B) is 80 from the viewpoint that durability can be imparted to the pressure-sensitive adhesive composition according to this embodiment, adhesion with the adherend can be increased, and durability can be increased. The temperature can be higher than 95 ° C, preferably higher than 95 ° C, and more preferably higher than 140 ° C.

  The content of the component (B) in the pressure-sensitive adhesive composition according to this embodiment is preferably 5% by mass or more and 35% by mass or less, and more preferably 10% by mass or more and 30% by mass or less. Further, from the viewpoint of improving compatibility with the component (A), the content of the component (B) is preferably 5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the component (A). More preferably, it is 10 to 55 mass parts.

1.3. (C) Component The 2nd compatibilizer which is (C) component has a property compatible with the soft segment which comprises (A) component, and is a liquid at normal temperature (23 degreeC). The “liquid” in the present invention includes a viscous viscoelastic liquid and other low-viscosity liquids. When the pressure-sensitive adhesive composition according to the present embodiment contains the component (C), the component (C) is compatible with the soft segment constituting the component (A), so that the wettability of the pressure-sensitive adhesive layer is improved. As a result of the increase, durability can be increased. Component (C) may be, for example, polybutene-based compounds, polyisobutylene compounds, a softening agent comprising an aliphatic hydrocarbon such as polyisoprene compound. Examples of the softener usable as the component (C) include commercially available softeners such as Nisseki Polybutene LV-7, LV-50, LV-100, HV-15, HV-35, HV-50 as polybutene compounds. HV-100, HV-300, HV-1900 and SV-7000 (all manufactured by JX Nippon Mining & Energy Corporation), polyisobutylene compounds as Tetrax 3T, 4T, 5T and 6T, High Mall 4H, 5H, 5. 5H and 6H (both manufactured by JX Nippon Oil & Energy Corporation), Claprene LIR-290 (manufactured by Kuraray Co., Ltd.) and the like can also be used as polyisoprene compounds.

  The content of the component (C) in the pressure-sensitive adhesive composition according to this embodiment is preferably 5% by mass or more and 35% by mass or less, and more preferably 10% by mass or more and 30% by mass or less. Further, from the viewpoint of improving compatibility with the component (A), the content of the component (C) is preferably 5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the component (A). More preferably, it is 10 to 55 mass parts. Furthermore, the total content of the component (B) and the component (C) is preferably 10 parts by mass or more and 80 parts by mass or less, and 15 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the component (A). More preferably, it is more preferably 20 parts by mass or more and 75 parts by mass or less.

1.4. Relative permittivity The relative permittivity of the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition according to the present embodiment is the relative permittivity measured at a frequency of 1.0 × 10 ^{2 to} 1.0 × 10 ⁶ Hz. Value. The relative dielectric constant of the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition according to this embodiment is 1 or more and 3.5 or less, preferably 1 or more and 3.2 or less, and 1 or more and 2.8 or less. More preferably it is. In the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition according to this embodiment, the relative dielectric constant at a frequency of 1.0 × 10 ⁶ Hz is 90% of the relative dielectric constant at a frequency of 1.0 × 10 ² Hz. It is preferable that it is 95% or more. Thus, the pressure-sensitive adhesive layer has a relative dielectric constant at a frequency of 1.0 × 10 ⁶ Hz of 90% or more of a relative dielectric constant at a frequency of 1.0 × 10 ² Hz. Since it has a stable relative dielectric constant, it is possible to prevent malfunction due to a high-frequency pulse in an image display device or an input / output device provided with the pressure-sensitive adhesive layer.

  In the present invention, the relative dielectric constant is a value measured by the method described in Examples described later.

1.5. (D) Component The 3rd compatibilizer which is (D) component has a property compatible with the soft segment which comprises (A) component at least, and is solid at normal temperature (23 degreeC). The component (D) can be a rosin tackifier resin, a terpene tackifier resin, or a hydrogenated alicyclic hydrocarbon resin. Examples of the component (D) include KE311 (light rosin-based tackifier resin, manufactured by Arakawa Chemical Co., Ltd.), TH130 (terpene phenol type tackifier resin, manufactured by Yasuhara Chemical Co., Ltd.), P-100 (hydrogenated alicyclic saturated hydrocarbon). Resin, manufactured by Arakawa Chemical Co., Ltd.) can be used.

  The content of the component (D) in the pressure-sensitive adhesive composition according to this embodiment is preferably 5% by mass or more and 35% by mass or less, and more preferably 10% by mass or more and 30% by mass or less. In addition, from the viewpoint of improving compatibility with the component (A), the content of the component (D) is preferably 5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the component (A). More preferably, it is 10 to 55 mass parts. Furthermore, the total content of the component (C) and the component (D) is preferably 10 parts by mass or more and 80 parts by mass or less, and 15 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the component (A). More preferably, it is more preferably 20 parts by mass or more and 75 parts by mass or less.

1.6. Applications The optical pressure-sensitive adhesive composition according to this embodiment can be used for bonding members constituting image display devices and input / output devices. A member to be bonded using the optical pressure-sensitive adhesive composition according to this embodiment is an optical member (for example, a polarizing film, a retardation film, an elliptically polarizing film, an antireflection film, a brightness enhancement film, a light diffusion film). And an optical film selected from the group consisting of hard coat films), a metal layer such as an ITO layer, or a substrate made of glass or plastic. More specifically, the optical pressure-sensitive adhesive composition according to this embodiment can be suitably used for bonding members constituting the touch panel type input / output device.

  The example which used the adhesive composition for optics which concerns on this embodiment for the bonding of the member which comprises a touchscreen type input / output apparatus is demonstrated with reference to FIG. FIG. 2 is a cross-sectional view schematically showing a configuration of an input / output device (touch panel type input / output device 100) according to an embodiment of the present invention. The touch panel type input / output device 100 according to the present embodiment includes a liquid crystal display device (LCD) 10, a touch panel unit 20, and an adhesive layer 30 provided between the LCD 10 and the touch panel unit 20. The adhesive layer 30 bonds the LCD 10 and the touch panel unit 20 together. The adhesive layer 30 is formed by, for example, applying the optical pressure-sensitive adhesive composition according to the present embodiment to the surface of a separator (not shown) and drying the adhesive sheet obtained by drying from the separator, and the LCD 10 and the touch panel. 20 between the two.

  As shown in FIG. 2, the LCD 10 is configured by laminating a polarizing plate 11, an adhesive layer 12, a liquid crystal panel 13, an adhesive layer 14, and a polarizing plate 15 in this order. The pressure-sensitive adhesive layer 12 bonds the polarizing plate 11 and the liquid crystal panel 13, and the pressure-sensitive adhesive layer 14 bonds the liquid crystal panel 13 and the polarizing plate 15.

  As shown in FIG. 2, the touch panel unit 20 is configured by laminating a scattering prevention film 16, an adhesive layer 17, an ITO layer 18, and a glass panel 19 in this order. The pressure-sensitive adhesive layer 17 bonds the scattering prevention film 16 and the ITO layer 18.

  The pressure-sensitive adhesive layers 12, 14, and 17 are the same as the pressure-sensitive adhesive layer 30, and an adhesive sheet obtained by applying the optical pressure-sensitive adhesive composition according to this embodiment to the surface of a separator (not shown) and drying it. It is peeled from the separator and installed.

1.7. Action Effect The optical pressure-sensitive adhesive composition according to the present embodiment includes the component (A), the component (B), and the component (C), whereby the dielectric constant of the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition. Since a low dielectric constant pressure-sensitive adhesive layer having a rate of 1 or more and 3.5 or less can be obtained, malfunction due to noise generated in an internal circuit included in the display device can be prevented.

  In the optical pressure-sensitive adhesive composition according to this embodiment, the component (B) is compatible with the hard segment constituting the component (A), and the component (C) is compatible with the soft segment constituting the component (A). By melting, durability can be enhanced by increasing wettability to the adherend. Furthermore, durability (heat resistance) can be improved because the optical adhesive composition which concerns on this embodiment contains (B) component whose softening point is 80 degreeC or more.

  More specifically, the improvement in wettability to the adherend due to the compatibility with the soft segment constituting the component (A) due to the component (C) and the softening point due to the component (B) The durability of the pressure-sensitive adhesive layer can be enhanced by two interactions with the improvement of heat resistance due to high components. Thereby, the adhesive layer excellent in durability, adhesiveness, and weather resistance can be obtained.

  In addition, the image display device and the input / output device using the optical pressure-sensitive adhesive composition according to the present embodiment are adhered to an adherend such as a liquid crystal cell with an appropriate adhesive force, and exhibit excellent durability. In addition, malfunction due to noise generated in the internal circuit can be prevented.

  In particular, the optical pressure-sensitive adhesive composition according to this embodiment can be suitably used for bonding members constituting the touch panel type input / output device.

1.7.1. Configuration of Known Input / Output Device In describing the operational effects of the optical pressure-sensitive adhesive composition according to this embodiment more specifically, the configuration of a known input / output device will be described. FIG. 3 is a cross-sectional view schematically showing a configuration of a known input / output device (touch panel type input / output device 200). The touch panel type input / output device 200 includes a liquid crystal display device (LCD) 110 and a touch panel unit 120. Since the gap agent layer 130 is provided at the end portion between the LCD 110 and the touch panel portion 120, a gap 140 is generated between the gap agent layers 130 at both ends.

  In recent years, there has been a demand for higher contrast of a display of a touch panel type input / output device. In order to achieve high contrast, for example, a means for filling the gap (the gap 140 in FIG. 3) between the image display unit and the touch sensor, which was previously a gap, with a transparent material such as an adhesive may be taken. It has become to. Thereby, reflection and refraction of light between the interfaces are suppressed, and as a result, high contrast can be achieved.

  However, when the gap 140 in FIG. 3 is filled with an adhesive or the like and bonded together, the touch sensor may malfunction due to high frequency noise generated from the internal circuit of the device or charging of the member. is there. In a touch panel type input / output device in which a gap is generated in a gap between an image display unit and a touch sensor (particularly, a capacitive touch sensor), since the relative permittivity of the air layer in the gap is 1, the air layer Since the noise is cut off by the gap, the occurrence of malfunction is prevented. On the other hand, when a transparent resin (for example, an acrylic adhesive having a relative dielectric constant of 4 or more) is used as a filler to fill a gap between the image display unit and the touch sensor, high frequency noise propagates to the touch sensor. As a result, malfunction may occur. The driving frequency and noise frequency are different, and it is required to prevent malfunction in a wide frequency range, but the relative dielectric constant of the adhesive layer formed using acrylic adhesive has frequency dependence. Tend.

  From such circumstances, in the touch panel type input / output device, it is desired to fill a gap between the image display unit and the touch sensor using an adhesive layer having a low relative dielectric constant in a wide frequency band.

1.7.2. On the other hand, according to the optical pressure-sensitive adhesive composition according to the present embodiment, the optical pressure-sensitive adhesive composition has a low relative dielectric constant in a wide frequency band (with a relative dielectric constant of Since the pressure-sensitive adhesive layer having low frequency dependency can be obtained, it is possible to prevent malfunction of the touch sensor due to the high dielectric constant of the pressure-sensitive adhesive layer. That is, the gap 140 in FIG. 3 is filled with the optical pressure-sensitive adhesive composition according to this embodiment, and a pressure-sensitive adhesive layer having a relative dielectric constant of 1 or more and 3.5 or less is provided in the gap 140, thereby touching. Sensor malfunction can be prevented.

  For example, in the touch panel type input / output device 100 according to the present embodiment shown in FIG. 2, an adhesive layer 30 is provided between the LCD 10 and the touch panel unit 20, and the adhesive layer 30 is used for the optical according to the present embodiment. Since it is formed from the pressure-sensitive adhesive composition, since the relative dielectric constant is as low as 1 or more and 3.5 or less, malfunction of the touch sensor due to the high relative dielectric constant of the pressure-sensitive adhesive layer can be prevented. .

  The hydrogenated block copolymer as component (A) is composed of a hard segment composed of a polymer component of an aromatic vinyl monomer, and a soft segment composed of a polymer component of a conjugated diene monomer. Due to this thermoplastic elastomer having excellent heat resistance due to the hard segment, and since the component (A) is a hydrogenated product, discoloration and modification due to the influence of coloring, ultraviolet rays and the like are prevented. As a result, the weather resistance is excellent. For this reason, the float and peeling by the gas (water vapor | steam and a volatile component derived from a to-be-adhered body) which generate | occur | produce from a to-be-adhered body under severe conditions can be suppressed. As a result, a touch panel type input / output device having high quality and excellent durability can be obtained.

1.8. Other Embodiments An optical pressure-sensitive adhesive composition according to another embodiment of the present invention comprises (i) a hydrogenated block copolymer, (ii) a first compatibilizer, and (iii) a second phase. An optical pressure-sensitive adhesive composition comprising: a solvent, wherein the (i) hydrogenated block copolymer comprises a hard segment composed of a polymer component of an aromatic vinyl monomer, and a conjugated diene monomer. And (ii) the first compatibilizer has the property of being compatible with the hard segment, and (iii) the second compatibilizer is: The pressure-sensitive adhesive layer having a property compatible with the soft segment and obtained from the optical pressure-sensitive adhesive composition has a dielectric constant of 1 or more and 3.5 or less. Here, as the (i) hydrogenated block copolymer, for example, the above-described component (A) can be used, and as the (ii) first compatibilizer, for example, the above-mentioned (B) For example, the component (C) and the component (D) (that is, a solid or liquid compatibilizer at normal temperature) may be used as the second compatibilizer. it can.

  When the optical pressure-sensitive adhesive composition includes the component (i), the component (ii), and the component (iii), the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition has a relative dielectric constant of 1 or more and 3. Therefore, malfunction caused by noise generated in an internal circuit included in the display device and malfunction caused by charging of a dielectric sandwiched between conductors can be prevented, and durability, adhesion and An adhesive layer having excellent weather resistance can be obtained.

2. Pressure-sensitive adhesive sheet The pressure-sensitive adhesive sheet according to this embodiment is obtained by applying the optical pressure-sensitive adhesive composition according to this embodiment to the surface of a separator and drying it. More specifically, the pressure-sensitive adhesive composition according to the present embodiment is applied onto a substrate with a gravure coater, Mayer bar coater, air knife coater, roll coater, etc., and the applied pressure-sensitive adhesive composition is heated to room temperature or heated. The pressure-sensitive adhesive sheet according to this embodiment may be produced by drying. The thickness of the pressure-sensitive adhesive sheet is usually in the range of 10 μm or less and 500 μm or less, preferably 20 μm or more and 300 μm or less.

3. Image Display Device and Input / Output Device An image display device according to another embodiment of the present invention includes an adhesive layer formed using the optical adhesive composition according to this embodiment. An example of the image display device according to the present embodiment is a liquid crystal display device.

  An input / output device according to another embodiment of the present invention includes a pressure-sensitive adhesive layer formed using the optical pressure-sensitive adhesive composition according to the present embodiment. In this case, examples of the input / output device include a capacitive touch panel type input / output device.

4). EXAMPLES Hereinafter, the present invention will be described based on the following examples, but the present invention is not limited to the examples.

4.1. Preparation of pressure-sensitive adhesive composition The components shown in Tables 1 and 2 were mixed to prepare pressure-sensitive adhesive compositions of Examples 1 to 21 and Comparative Examples 1 to 18, respectively. In addition, the 50-micrometer-thick adhesive sheet used with the evaluation method mentioned later was obtained by apply | coating each adhesive composition to the surface of a separator, and making it dry.

4.2. Evaluation method 4.2.1. Relative permittivity A pressure-sensitive adhesive sheet having a thickness of 50 μm was attached to a copper foil having a thickness of 100 μm, and further attached to a copper foil having a thickness of 100 μm to obtain a measurement sample. A Toyo Technica LCR meter 6440B was used to connect to the copper foil, and the relative dielectric constant was calculated under the conditions of 23 ° C. and 65% RH. In addition, about the hydrogenated block copolymer which comprises the adhesive composition of Example 1, the result of having measured the dielectric constant by changing the measurement frequency is shown in FIG. In addition, the same measurement was performed also about the acrylic polymer which comprises the adhesive composition of Comparative Examples 13 and 17 as a comparison object.

4.2.2. Heat-resistant foaming property An adhesive sheet having a thickness of 50 μm was transferred to a PET having a thickness of 100 μm, adhered to a polycarbonate MR-58 made by Mitsubishi Plastics, and allowed to stand in an environment of 85% RH at 85 ° C. The appearance of the adhesive sheet was visually evaluated according to the following criteria.
(Evaluation)
◎: appearance not abnormality was observed ○: The following bubble diameter 0.1mm per 1cm ² was observed 1 or less △: of the following bubble diameter 0.1mm were observed two to five per 1cm ^2, Or, bubbles with a diameter of more than 0.1 mm and 1.0 mm or less were observed. X 6 or more bubbles were observed per 1 cm ² , or bubbles with a diameter of more than 1.0 were recognized.

4.2.3. Wet and heat whitening property A 50 μm thick adhesive sheet was transferred to a 100 μm thick PET, which was attached to a glass plate and allowed to stand in an environment of 60 ° C. and 95% RH. The wet heat whitening property was measured with a haze meter.

4.2.4. Evaluation of Adhesive Strength An adhesive sheet having an adhesive layer thickness of 50 μm was cut into a strip shape having a width of 20 mm, the separator was peeled off, bonded to a glass substrate, and subjected to 3 reciprocating pressure bonding with a 2 kg roller. After 20 minutes, the film was peeled at a peeling speed of 0.3 m / min and a peeling angle of 180 °, and the adhesive force at that time was measured (unit: N / 20 mm).

4.2.5. Weather resistance Using a xenon weather meter, the hue before and after the test was comparatively measured with a light / dark cycle continuous lighting at a black panel temperature of 63 ± 3 ° C.
(Evaluation)
A: Color difference ΔE * is 3.2 or less ○: Color difference ΔE * is more than 3.2 and 6.5 or less Δ: Color difference ΔE * is more than 6.5 and 13.0 or less ×: Color difference ΔE * is more than 13.0

In addition, the meaning of the abbreviation in Table 1 and Table 2 is as follows.
SEPS1: Styrene / ethylene-propylene / styrene type block copolymer (hydrogenated product of styrene-isoprene-styrene type block polymer; styrene content 13%)
SEPS2: Styrene / ethylene-propylene / styrene type block copolymer (hydrogenated styrene-isoprene-styrene type block polymer; styrene content 20%)
SEPS3: Styrene / ethylene-propylene / styrene type block copolymer (hydrogenated product of styrene-isoprene-styrene type block polymer; styrene content 65%)
SEBS: Styrene / ethylene-butylene / styrene type block polymer (styrene content 30%) (All of the above SEPS1, SEPS2, SESP3 and SEBS have a hydrogenation rate of 90% or more)
SIS: Styrene-isoprene-styrene block polymer SBS: Styrene-butadiene-styrene block polymer Acrylic polymer 1: n-butyl acrylate / methyl acrylate / 2-hydroxyethyl acrylate = 60/30/10 (mass ratio)
Acrylic polymer 2: 2-ethylhexyl acrylate / methyl acrylate / 2-hydroxyethyl acrylate = 60/30/10 (mass ratio)
Acrylic polymer 3: methyl methacrylate / n-butyl acrylate = 6.5 / 87 / 6.5 (mass ratio) ABA type triblock polymer FMR-0150: aromatic tackifying resin having a softening point of 145 ° C. (Mitsui Chemicals) (Made by company)
FTR-6100: Aromatic tackifying resin having a softening point of 100 ° C. (Mitsui Chemicals)
Crystallex 3100: Aromatic tackifying resin with a softening point of 100 ° C. (manufactured by Eastman Chemical Co.)
Picolastic A5: Aromatic tackifying resin having a softening point of 5 ° C. (manufactured by Eastman Chemical Co.)
DOP: Dioctyl phthalate (Eastman Chemical)
KE311: Light-colored rosin tackifier resin (Arakawa Chemical Co., Ltd.)
TH130: terpene phenol type tackifying resin (manufactured by Yasuhara Chemical)
P-100: Hydrogenated alicyclic saturated hydrocarbon resin (Arakawa Chemical Co., Ltd.)

4.3. Evaluation results From the results shown in Table 1, the pressure-sensitive adhesive compositions of Examples 1 to 21 of the present application include the component (A), the component (B), and the component (C), and thereby the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition. It is possible to obtain a pressure-sensitive adhesive layer having a relative dielectric constant of 1 or more and 3.5 or less and having excellent durability (heat-resistant foaming property and wet heat whitening property) and weather resistance.

  On the other hand, as shown in Table 2, it can be understood that the compositions of Comparative Examples 1 to 5 of the present application are inferior in durability (heat-resistant foaming property) because they do not contain the component (B). In particular, in Comparative Example 1 of the present application, instead of the first compatibilizer having a softening point of 80 ° C. or higher, which is the component (B), an aromatic tackifying resin having a softening point of less than 80 ° C. is used. I can understand that it is inferior.

  Moreover, since the composition of this-application comparative example 6 thru | or 8 does not contain (C) component, it can be understood that it is inferior to durability (heat-resistant foaming property). Furthermore, it can be understood that the compositions of Comparative Examples 9 to 11 are inferior in weather resistance because a non-hydrogenated block copolymer is used in place of the component (A). In addition, it can be understood that in the compositions of Comparative Examples 12 to 15, 17 and 18 of the present application, an adhesive layer having a high relative dielectric constant was obtained because an acrylic polymer was used instead of the component (A). In addition, in the composition of this-application comparative example 16, since DOP (dioctyl phthalate) was used instead of (C) component, it can be understood that it is inferior in heat resistance.

  Moreover, according to FIG. 1, the adhesive layer formed from the adhesive composition of Example 1 has a stable dielectric constant in a wide frequency band. On the other hand, the relative permittivity of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive compositions of Comparative Examples 13 and 17 varies greatly depending on the frequency. From this result, it can be understood that by using the pressure-sensitive adhesive composition of the present invention, a pressure-sensitive adhesive layer having a low relative dielectric constant of 1 or more and 3.5 or less and a low frequency dependence of the relative dielectric constant can be obtained. .

Claims (14)

(A) a hydrogenated block copolymer;
(B) a first compatibilizer;
(C) a second compatibilizer, comprising an optical pressure-sensitive adhesive composition,
The (A) hydrogenated block copolymer has a hard segment composed of a polymer component of an aromatic vinyl monomer and a soft segment composed of a polymer component of a conjugated diene monomer,
The (B) first compatibilizer has a property compatible with the hard segment, and has a softening point of 80 ° C. or higher,
The (C) second compatibilizer has a property compatible with the soft segment and is liquid at room temperature (23 ° C.).
The content of the (B) first compatibilizer is 5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the (A) hydrogenated block copolymer,
The (B) first compatibilizer is an aromatic tackifying resin,
The dielectric constant of the adhesive layer obtained from the optical pressure-sensitive adhesive composition Ri der 1 to 3.5,
The pressure-sensitive adhesive layer has a specific dielectric constant at a frequency 1.0 × ¹⁰ 6 Hz is Ru der 90% relative dielectric constant at a frequency 1.0 × ¹⁰ 2 Hz, optical pressure-sensitive adhesive composition. (A) a hydrogenated block copolymer;
(B) a first compatibilizer;
(C) a second compatibilizer, comprising an optical pressure-sensitive adhesive composition,
The (A) hydrogenated block copolymer has a hard segment composed of a polymer component of an aromatic vinyl monomer and a soft segment composed of a polymer component of a conjugated diene monomer,
The (B) first compatibilizer has a property compatible with the hard segment, and has a softening point of 80 ° C. or higher,
The (C) second compatibilizer has a property compatible with the soft segment and is liquid at room temperature (23 ° C.).
The content of the (B) first compatibilizer is 5% by mass or more and 35% by mass or less,
The (B) first compatibilizer is an aromatic tackifying resin,
The dielectric constant of the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition is 1 or more and 3.5 or less,
The pressure-sensitive adhesive layer is an optical pressure-sensitive adhesive composition, wherein a relative dielectric constant at a frequency of 1.0 × 10 ⁶ Hz is 90% or more of a relative dielectric constant at a frequency of 1.0 × 10 ² Hz. The optical pressure-sensitive adhesive composition according to claim 1 or 2 , wherein the content of the hard segment in the (A) hydrogenated block copolymer is 5% by mass or more and 70% by mass or less. The hydrogenation rate of a double bond contained in the polymer component of the conjugated diene monomer constituting the (A) hydrogenated block copolymer is 90% or more, according to any one of claims 1 to 3. The optical pressure-sensitive adhesive composition according to the description. The aromatic tackifying resin is an aromatic petroleum resin, a styrene polymer, an α-methylstyrene polymer, a styrene- (α-methylstyrene) copolymer, or a styrene-aliphatic hydrocarbon copolymer. , styrene - (alpha-methylstyrene) - aliphatic hydrocarbon copolymer and a styrene - is at least one selected from the group consisting of an aromatic hydrocarbon type copolymer, any one of claims 1 to 4 optical adhesive composition according to item 1. The (C) second compatibilizer is at least one selected from the group consisting of a polybutene compound, a polyisobutylene compound, and a polyisoprene compound, according to any one of claims 1 to 5 . Optical pressure-sensitive adhesive composition. The optical pressure-sensitive adhesive composition according to any one of claims 1 to 6 , wherein the acid value of the optical pressure-sensitive adhesive composition is 1 or less. Wherein (C) the content of the second phase solvent, wherein (A) is not more than 60 parts by mass 5 parts by mass or more with respect to the hydrogenated block copolymer 100 parts by weight, any one of claims 1 to 7 1 The optical pressure-sensitive adhesive composition according to Item. The total content of the (B) first compatibilizer and the (C) second compatibilizer is 10 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the (A) hydrogenated block copolymer. The optical pressure-sensitive adhesive composition according to any one of claims 1 to 8 . And (D) a third compatibilizer that is compatible with the soft segment and is solid at room temperature (23 ° C.),
The optical component according to any one of claims 1 to 9 , wherein the (D) third compatibilizer is a rosin tackifier resin, a terpene tackifier resin, or a hydrogenated alicyclic hydrocarbon resin. Adhesive composition. The optical adhesive composition according to any one of claims 1 to 10 , which is used for bonding members constituting a touch panel type input / output device. The optical adhesive sheet obtained by apply | coating the optical adhesive composition of any one of Claim 1 thru | or 11 to the surface of a separator, and drying. The image display apparatus containing the adhesive layer formed using the optical adhesive composition of any one of Claims 1 thru | or 11 . It claims 1 to comprising a pressure-sensitive adhesive layer formed by using an optical pressure-sensitive adhesive composition according to any one of 11, input-output devices.

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