JP6131153B2 - Optical pressure-sensitive adhesive composition, image display device, and input / output device - Google Patents

Description

  The present invention relates to an optical pressure-sensitive adhesive composition, 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.

  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

  By the way, with the miniaturization of electronic components constituting the image display device and the input / output device, for example, high frequency noise generated in the circuit, or charging of a dielectric sandwiched between conductors during driving, It may be caused to malfunction due to noise generated in the internal circuit included in the component.

  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 there is a concern that it may cause malfunction due to high frequency noise.

  In addition, constituent members constituting an image display device or an input / output device that have a relatively large step or deep unevenness (for example, unevenness of 5 μm or more) on the surface are those to which the adhesive composition is bonded. There is also.

  When the pressure-sensitive adhesive sheet obtained from the pressure-sensitive adhesive composition is bonded to the surface of the member having such a step, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive sheet does not have an appropriate flexibility, and the step of the member It cannot follow and sufficiently deform, resulting in a gap around the step. Such a gap causes a decrease in contrast of the display of the image display device or the input / output device, and there is a concern that peeling may occur under high temperature conditions.

  In view of the above circumstances, the present inventors have reduced the relative permittivity of the pressure-sensitive adhesive composition used in the manufacture of image display devices and input / output devices, and the surface roughness of the member to which the pressure-sensitive adhesive composition is bonded. As a result of intensive studies on the provision of flexibility that can be followed, it was found that the pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition containing a specific material has a low relative dielectric constant and has a predetermined flexibility. .

  The present invention relates to an optical pressure-sensitive adhesive composition capable of obtaining a pressure-sensitive adhesive layer having a reduced dielectric constant and excellent flexibility, and an optical pressure-sensitive adhesive sheet formed using the optical pressure-sensitive adhesive composition And an image display device and an input / output device including a pressure-sensitive adhesive layer formed using the optical pressure-sensitive adhesive composition.

  The optical pressure-sensitive adhesive composition according to one embodiment of the present invention includes (A) a hydrogenated block copolymer, (B) a first compatibilizer, and (C) a second compatibilizer. The (A) hydrogenated block copolymer is composed of a hard segment composed of a polymer component of an aromatic vinyl monomer and a polymer component of a conjugated diene monomer. The (B) first compatibilizer has a property of being compatible with the hard segment, and has a softening point of 50 ° C. or less. The compatibilizer has a property of being compatible with the soft segment and has a softening point of 50 ° C. or higher and lower than 140 ° C., and 2 to 50 masses per 100 parts by mass of the (A) hydrogenated block copolymer. Part of the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition has a relative dielectric constant of 1 to 3. It is.

  When the optical pressure-sensitive adhesive composition contains a predetermined amount of the components (A), (B) and (C), the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition has a relative dielectric constant of 1 to 1. 3.5, which is excellent in flexibility.

  That is, an optical pressure-sensitive adhesive composition capable of obtaining a pressure-sensitive adhesive layer having a reduced dielectric constant and excellent flexibility as compared with an optical pressure-sensitive adhesive composition not having the above-described configuration, Provided are an optical pressure-sensitive adhesive sheet formed using the optical pressure-sensitive adhesive composition, and an image display device and an input / output device including a pressure-sensitive adhesive layer formed using the optical pressure-sensitive adhesive composition.

It is a figure which illustrates typically the relationship between the dielectric constant and frequency of the adhesive layer obtained from the adhesive composition of Example 1 of this invention. It is sectional drawing which shows typically the structure of the input / output device (touch panel type input / output device) which concerns on one Embodiment of this invention. It is sectional drawing which shows typically the structure of the input / output apparatus (touch panel type input / output device) which concerns on other embodiment of this invention. It is sectional drawing which shows typically the structure of the input / output apparatus (touch panel type input / output device) which concerns on other embodiment of this invention. It is sectional drawing which shows typically the structure of a well-known output / input device (touchscreen type input / output device). It is a figure which shows typically that the adhesive sheet cannot fill the level | step difference on a glass plate, and the space | gap and air bubbles are visually recognized around the level | step difference. It is a figure which shows typically that the adhesive sheet can fill the level | step difference on a glass plate, and the space | gap and the bubble are not visually recognized around the level | step difference. It is a figure which shows the evaluation result of each adhesive composition of Examples 1-20 and the adhesive sheet obtained from this adhesive composition. It is a figure which shows the evaluation result of each adhesive sheet of Comparative Examples 1-11 and the adhesive sheet obtained from this adhesive composition.

  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 one 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 to 3.5.

1.1. (A) Component The hydrogenated block copolymer (A) is a soft segment composed of a hard segment composed of a polymer component of an aromatic vinyl monomer and a polymer component of a conjugated diene monomer. And a thermoplastic elastomer having segments. 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, relative permittivity is 1 to 3.5).

  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 them, from the viewpoint of excellent compatibility with the component (B), styrene- (ethylene-propylene) -styrene type block copolymer (SEPS), styrene- (ethylene-butylene) -styrene type block copolymer. ABA hydrogenated block copolymers such as (SEBS) are particularly preferred. These may be used singly or in combination of two or more.

  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 to 70% by mass, and 10 to 60% by mass. More preferably. 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.

  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 to 90% by mass, and more preferably 55 to 80% by mass.

1.2. (B) Component The 1st compatibilizer which is a component (B) has a property compatible with the hard segment which comprises (A) component, and a softening point is 50 degrees C or less.

  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. Flexibility is imparted to the layer and adhesion to the adherend is increased.

  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, the polymer polymerized only from the aromatic vinyl monomer and the component (B) are mixed using a solvent as necessary, and the mixture becomes cloudy or contains the polymer. When the phenomenon that the phase and the phase containing the component (B) are separated is not observed visually, the component (B) is compatible with the hard segment constituting the component (A).

  The component (B) can be, for example, an aromatic tackifying 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, Picolastic A5 (softening point 5 ° C., aromatic tackifying resin, manufactured by Eastman Chemical Co.), Picotack 1020 (softening point 5 ° C., aromatic tackifying resin, Eastman Chemical Co., Ltd.) Picotac 7050 (softening point 50 ° C., aromatic tackifying resin, manufactured by Eastman Chemical Co., Ltd.) or the like may be used.

  From the viewpoint of imparting flexibility to the pressure-sensitive adhesive composition according to the present embodiment and improving the adhesion to the adherend, the softening point of the component (B) is 50 ° C. or lower and 40 ° C. or lower. Preferably, it is 30 degrees C or less. Moreover, there is no restriction | limiting in particular about the lower limit of the softening point of B), However It is good also as being 0 degreeC or more.

  The compounding quantity of (B) component in the adhesive composition which concerns on this embodiment is good also as 30-100 mass parts with respect to 100 mass parts of (A) component. Moreover, it is preferable that content of (B) component is 40-90 mass parts with respect to 100 mass parts of (A) component from a viewpoint which can improve compatibility with (A) component, 45-45. More preferably, it is 85 parts by mass.

  In order to reduce the relative dielectric constant of the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition, in the pressure-sensitive adhesive composition according to this embodiment, the component (B) is (A) a hydrogenated block copolymer. 30 parts by mass or more is preferably compounded with respect to 100 parts by mass, more preferably 40 parts by mass or more, and even more preferably 45 parts by mass or more.

  Specifically, in the pressure-sensitive adhesive composition according to the embodiment, the component (B) is contained in an amount of 30 parts by mass or more based on 100 parts by mass of the (A) hydrogenated block copolymer. The relative dielectric constant of the pressure-sensitive adhesive layer obtained from the above is as low as 1 to 3.0. Moreover, the relative dielectric constant of the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition may be 1 to 2.5 or 1 to 2.3.

1.3. (C) The 2nd compatibilizer which is a component (C) has a property compatible with the soft segment which comprises (A) component, and its softening point is 50 degreeC or more and less than 140 degreeC.

  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 (C). More specifically, the polymer polymerized only from the conjugated diene monomer and the component (C) are mixed using a solvent as necessary, and the mixture becomes turbid or contains the polymer. When the phenomenon that the phase containing the component (C) and the phase containing the component (C) are not visually observed, the component (C) is compatible with the soft segment constituting the component (A).

  By including the component (C) in the pressure-sensitive adhesive composition according to the present embodiment, the component (C) is compatible with the soft segment constituting the component (A), so that the wettability of the pressure-sensitive adhesive layer is increased. In addition, the tackiness is increased.

  Component (C) may be, for example, an alicyclic saturated hydrocarbon compound, a terpene phenol compound (terpene phenol copolymer), or the like. Examples of compounds that can be used as the component (C) include YS Polystar U130 (softening point 130 ° C., terpene phenol copolymer, manufactured by Yasuhara Chemical Co., Ltd.), YS Polystar U115 (softening point 115 ° C., terpene phenol copolymer, manufactured by Yasuhara Chemical Co., Ltd.). ), YS Polystar T130 (softening point 130 ° C., terpene phenol copolymer, manufactured by Yasuhara Chemical Co.), YS Polystar T115 (softening point 115 ° C., terpene phenol copolymer, manufactured by Yasuhara Chemical Co.), YS Polystar T100 (softening point 100 ° C., terpene) Phenol copolymer, manufactured by Yasuhara Chemical Co., Ltd.), YS Polystar T80 (softening point 80 ° C., Terpene phenol copolymer, manufactured by Yasuhara Chemical Co., Ltd.), YS Polystar G125 (softening point 125 ° C., terpene phenol) Copolymerization, Yasuhara Chemical Co., Ltd.), YS Polystar N125 (softening point 125 ° C., terpene phenol copolymer, Yasuhara Chemical Co., Ltd.), YS Polystar K125 (softening point 125 ° C., terpene phenol copolymer, Yasuhara Chemical Co., Ltd.), YS Polystar TH130 ( Softening point 130 ° C, terpene phenol copolymer, Yashara Chemical Co., Ltd.), Alcon P-90 (softening point 90 ° C, alicyclic saturated hydrocarbon compound, Arakawa Chemical Co., Ltd.), Alcon P-100 (softening point 100 ° C, fat Acyclic saturated hydrocarbon compound, manufactured by Arakawa Chemical Co., Ltd.), Alcon P-115 (softening point 115 ° C., alicyclic saturated hydrocarbon compound, manufactured by Arakawa Chemical Co., Ltd.), Alcon P-125 (softening point 125 ° C., alicyclic) Saturated hydrocarbon compound, manufactured by Arakawa Chemical Co., Ltd.), Alcon M-90 (softening point 90 ° C, alicyclic saturated hydrocarbon) Product, manufactured by Arakawa Chemical Co., Ltd.), Alcon M-100 (softening point 100 ° C., alicyclic saturated hydrocarbon compound, manufactured by Arakawa Chemical Co.), Alcon M-115 (softening point 115 ° C., alicyclic saturated hydrocarbon compound, Arakawa Chemical Co., Ltd.), Alcon M-135 (softening point 135 ° C., alicyclic saturated hydrocarbon compound, Arakawa Chemical Co., Ltd.) and the like may be used.

  From the viewpoint of imparting flexibility to the pressure-sensitive adhesive composition according to the present embodiment and improving adhesion and adhesion to the adherend, the softening point of the component (C) can be 50 ° C. or higher, 90 It is preferable that the temperature is higher than 100 ° C., more preferably higher than 100 ° C. Further, the softening point of the component (C) is less than 140 ° C., and when it is 140 ° C. or more, it is difficult to control the adhesive force, which may cause a zipping phenomenon.

  In the pressure-sensitive adhesive composition according to this embodiment, the component (C) is contained in an amount of 2 to 50 parts by mass or more with respect to 100 parts by mass of the (A) hydrogenated block copolymer. This is because the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition can achieve desirable pressure-sensitive adhesiveness and step following ability.

  Moreover, the compounding quantity of (C) component in the adhesive composition which concerns on this embodiment is good also as being 5-50 mass parts with respect to 100 mass parts of (A) component. In addition, from the viewpoint of increasing the compatibility with the component (A) and obtaining a preferable adhesive property and step following property with the obtained pressure-sensitive adhesive layer, the content of the component (C) is the component (A) 100. It is preferable that it is 7-48 mass parts with respect to a mass part, and it is more preferable that it is 9-45 mass parts.

  In addition, the viewpoint that the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition can have a lower relative dielectric constant, and the compatibility between the components contained in the optical pressure-sensitive adhesive composition can be further increased. From the above, the optical pressure-sensitive adhesive composition is such that (B) the second compatibilizer is blended in an amount of 5 to 55 parts by mass with respect to 30 to 80 parts by mass of the first compatibilizer. Also good. By blending the component (B) and the component (C) in the optical pressure-sensitive adhesive composition in the above ratio, the effect of the present invention is further enhanced.

  Moreover, the relationship of the compounding quantity of the (C) 2nd compatibilizer with respect to the compounding quantity of the (B) 1st compatibilizer in the optical adhesive composition is (B) :( C) = (30-80 mass parts). ): (5-55 parts by mass). Also, the blending amount of (B) / (C), which is the ratio between the blending amount of (B) the first compatibilizer and the blending amount of (C) the second compatibilizer in the optical pressure-sensitive adhesive composition. A compounding quantity is good also as being more than 1.0 and 16 or less. The effect of this invention will further increase by making the compounding quantity of (B) component and (C) component in an optical adhesive composition into the above ratios.

1.4. Relative dielectric constant The relative dielectric constant of the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition according to the present embodiment is the relative dielectric constant 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 to 3.5, preferably 1 to 3.0, and preferably 1 to 2.5. More preferably, it is particularly preferably 1 to 2.3. 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, more preferably 97% 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, malfunction caused by high frequency noise is reduced in the image display device or 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 (D) component is an arbitrary component which can be added to the adhesive composition of this application other than the said (A)-(C) component. The component (D) may be a third compatibilizer having a property compatible with at least the soft segment constituting the component (A). Moreover, (D) component is good also as being liquid at normal temperature (23 degreeC).

  The “liquid” in the present invention includes viscous viscoelastic liquids and other low viscosity liquids. By including the component (D) in the pressure-sensitive adhesive composition according to the present embodiment, the component (D) is compatible with the soft segment constituting the component (A), so that the wettability of the pressure-sensitive adhesive layer is increased. As a result, durability can be enhanced.

  Moreover, (D) component is good also as being a softener containing aliphatic hydrocarbons, such as a polybutene type compound, a polyisobutylene type compound, a polyisoprene type compound, for example. As the softener that can be used as the component (D), 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) and Claprene LIR-290 (manufactured by Kuraray Co., Ltd.) may be used as the polyisoprene compound.

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.

  Moreover, glass is particularly suitable as the adherend of the optical pressure-sensitive adhesive composition according to this embodiment. The amount of gas contained in the glass is very small. For this reason, for example, the amount of outgas released from the glass over time is extremely small, and the adhesive layer obtained from the adhesive composition maintains physical properties such as adhesiveness without being affected by the outgas. is there.

  In addition, since the optical pressure-sensitive adhesive composition according to this embodiment is excellent in flexibility, the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition according to this embodiment has excellent step following ability. For this reason, for example, it may be used not only for a member having a flat surface but also for a member having an uneven surface. More specifically, a pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition according to the present embodiment is used for a member having a printed level difference on a surface, a member having an electrode film formed thereon and a level difference on the surface, and the like. It is good.

  An example in which the optical pressure-sensitive adhesive composition according to this embodiment is used for bonding members constituting a touch panel type input / output device will be described with reference to FIG. 2A. FIG. 2A is a cross-sectional view schematically showing a configuration of an input / output device (touch panel type input / output device 100A) according to an embodiment of the present invention. The touch panel type input / output device 100 </ b> A according to the present embodiment includes an image display device 10, a touch panel unit 20, and an adhesive layer 30 provided between the image display device 10 and the touch panel unit 20.

  Here, for example, the image display device 10 may be a liquid crystal display device (LCD) 10. In FIG. 2A, the image display device 10 will be specifically described as an LCD 10.

  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. 2A, 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.

  Moreover, as shown in FIG. 2A, the touch panel unit 20 may be configured by a scattering prevention film 16, an adhesive layer 17, an ITO layer 18, and a glass panel 19 laminated in this order. . Here, the pressure-sensitive adhesive layer 17 bonds the scattering prevention film 16 and the ITO layer 18 together.

  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.

  Moreover, the other 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 device is demonstrated with reference to FIG. 2B. FIG. 2B is a cross-sectional view schematically showing a configuration of an input / output device (touch panel type input / output device 100B) according to another embodiment of the present invention.

  The touch panel type input / output device 100B shown in FIG. 2B bonds the image display device 10 configured by, for example, a liquid crystal display, the touch panel unit 20 including the sensor electrode 12a on the surface, the image display device 10 and the touch panel unit 20. And an adhesive layer 30.

As shown in FIG. 2B, the surface of the adhesive sheet 10 and the cover glass 12 to be attached has a convex portion derived from the sensor electrode 21a (a step d ₁ generated at the joint between the cover glass 12 and the sensor electrode 21a). Existing. Since the optical pressure-sensitive adhesive composition of the present invention has flexibility, even when the pressure-sensitive adhesive layer 30 obtained from the composition is used for bonding the touch panel portion 20 that is an adherend having a step d ₁ , By the pressure-sensitive adhesive layer 30 following the step d ₁ (having excellent step followability), generation of bubbles between the adherend and the adherend is suppressed.

  Moreover, the other 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 device is demonstrated with reference to FIG. 2C. FIG. 2C is a cross-sectional view schematically showing a configuration of an input / output device (touch panel type input / output device 100C) according to another embodiment of the present invention.

The touch panel type input / output device 100C shown in FIG. 2C further includes a cover glass 40 on the uppermost surface of the touch panel type input / output device 110 shown in FIG. 2B. The cover glass 40 is provided with a print layer 41. That is, a convex portion (printing step d ₂ ) derived from the printing layer 41 exists on the surface of the cover glass 40.

As shown in FIG. 2C, since the optical pressure-sensitive adhesive composition of the present invention has flexibility, the pressure-sensitive adhesive layer 30 (30a, 30b) obtained from the composition includes the cover glass 12, the sensor electrode 21a, Even when it is used for bonding the touch panel 20 or the cover glass 40 which is an adherend having the step d ₁ generated at the bonded portion or the step d ₂ generated at the bonded portion between the cover glass 40 and the printed layer 41 The agent layer 30 follows the step d ₁ or the step d ₂ (has excellent step followability) to suppress the generation of bubbles between the adherend and the adherend.

  That is, the optical pressure-sensitive adhesive composition according to this embodiment includes the component (B) having a softening point of 50 ° C. or lower and the component (C) having a softening point of 50 ° C. or higher and lower than 140 ° C. In the temperature range (for example, 0-100 degreeC) at the time of using the apparatus containing this adhesive layer when bonding the adhesive layer obtained using the optical adhesive composition which concerns on embodiment, this adhesive The agent layer can retain flexibility. As a result, excellent step following ability can be exhibited, so that generation of bubbles between the adherend and the adherend can be suppressed.

1.7. Effect The optical pressure-sensitive adhesive composition according to this 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 to 3.5 can be obtained, malfunction due to noise generated in an internal circuit included in the display device is suppressed.

  In the optical pressure-sensitive adhesive composition according to this embodiment, the component (B) having a softening point of 50 ° C. or lower is compatible with the hard segment constituting the component (A), and the softening point is 50 ° C. or higher and 140 ° C. The component (C), which is less than the amount, is compatible with the soft segment constituting the component (A) and contains a predetermined amount of the component (C), so that the component (B) increases the flexibility of the hard segment and (C ) Component can bring the hardness of the soft segment closer to the hardness of the hard segment. Thereby, the hardness of the whole composition can be made more uniform, and flexibility can be imparted to the whole composition. As a result, the step following property of the pressure-sensitive adhesive layer obtained using the composition can be enhanced.

  More specifically, the adhesiveness due to the compatibility with the soft segment constituting the component (A) due to the component (C), the improvement of the step following property, and the softening point due to the component (B) are low. The desired pressure-sensitive adhesive layer can be realized by the two interactions of imparting flexibility by components and suppressing the relative dielectric constant.

  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 have excellent step followability. And malfunction due to noise generated in the internal circuit is suppressed.

  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, an air layer 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 space between the image display unit and the touch sensor (air layer 140 in FIG. 3), which was previously an air layer, with a transparent material such as an adhesive is taken. It has become like this. Thereby, reflection and refraction of light between the interfaces are suppressed, and as a result, high contrast can be achieved.

  However, when the air layer 140 of FIG. 3 is filled with an adhesive or the like and the members are bonded together, the touch sensor may malfunction due to high frequency noise generated from the internal circuit of the device or charging of the members. Is concerned. In a touch panel type input / output device in which an air layer is provided between an image display unit and a touch sensor (particularly, a capacitive touch sensor), the air layer 140 has a relative dielectric constant of 1, so that noise is generated by the air layer 140. Since it is blocked, the risk of malfunction is extremely low. 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, the concern of causing malfunctions increases. 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. In contrast, according to the optical pressure-sensitive adhesive composition of the present embodiment, the optical pressure-sensitive adhesive composition has a low relative dielectric constant (relative dielectric constant) in a wide frequency band. 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 air layer 140 of FIG. 3 is filled using the optical pressure-sensitive adhesive composition according to this embodiment, and a pressure-sensitive adhesive layer having a relative dielectric constant of 1 to 3.5 is provided instead of the air layer 140. Thus, the malfunction of the touch sensor is suppressed as compared with the case where the pressure-sensitive adhesive layer formed using the acrylic pressure-sensitive adhesive is provided instead of the air layer 140.

  For example, in the touch panel type input / output device 100 according to the present embodiment illustrated in FIGS. 2A to 2C, the adhesive layer 30 is provided between the LCD 10 and the touch panel unit 20 (or between the touch panel unit 20 and the cover glass 40). Since this adhesive layer 30 is formed from the optical adhesive composition according to this embodiment, since the relative dielectric constant is as low as 1 to 3.5, an acrylic adhesive is used. Compared to the case where the formed pressure-sensitive adhesive layer is used, malfunction of the touch sensor due to the relative dielectric constant of the pressure-sensitive adhesive layer is suppressed.

  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. be able to. As a result, a touch panel type input / output device having high quality and excellent durability 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. Moreover, the thickness of an adhesive sheet is 10-500 micrometers normally, Preferably it is about 20-300 micrometers.

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 and the like 4.1.1. Preparation of Adhesive Composition FIG. 5A is a diagram showing the evaluation results of the adhesive compositions of Examples 1 to 20 and the adhesive sheets obtained from the adhesive composition. Moreover, FIG. 5B is a figure which shows the evaluation result of the adhesive composition of Comparative Examples 1-11 and each adhesive sheet obtained from this adhesive composition.

  Each component was mixed by the mixing | blending shown by FIG. 5A and 5B, and the adhesive composition of Examples 1-20 and Comparative Examples 1-11 was prepared, 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.

4.1.2. Preparation of Compound A Shown in FIG. 5A A compound A shown in FIG. 5A is a tackifier resin (tackfire), which is an embodiment of the component (C).

  Compound A, 100 parts by mass of styrene and 2 parts by mass of α-methylstyrene dimer were added to the flask, and after addition of 90 parts by mass of toluene in the flask, the reaction started while refluxing at 110 ° C. 0.1 parts by mass of azobisisobutyronitrile (AIBN) was added as an agent to initiate the reaction.

  0.2 parts by mass of AIBN was added again 2 hours after the start of the reaction, and 0.5 parts by mass of AIBN was further added after 2 hours (that is, 4 hours after the start of the reaction). The reaction was terminated when 6 hours had elapsed from the start of the reaction to obtain a styrene polymer (compound A) as one embodiment of the component (C).

4.2. Evaluation method 4.2.1. A pressure-sensitive adhesive sheet having a thickness of 50 μm was attached to a copper foil having a relative dielectric constant 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.

  FIG. 1 is a diagram schematically illustrating the relationship between the relative dielectric constant and frequency of the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition of Example 1 of the present invention. Here, the same measurement was performed for the component (A) of Example 1 that was replaced with the acrylic polymer 1 (acrylic adhesive 1) and the component that was replaced with the acrylic polymer 2 (acrylic adhesive 2). The results are shown in FIG. 1 for comparison.

  According to FIG. 1, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition of Example 1 has a stable relative dielectric constant in a wide frequency band. On the other hand, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition in which the component (A) of Example 1 is replaced with the acrylic polymer 1 (acrylic pressure-sensitive adhesive 1) and the acrylic polymer 2 is replaced. The relative permittivity 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 to 3.5 and a low frequency dependence of the relative dielectric constant can be obtained.

4.2.2. Evaluation of level difference followability The 50 μm thick adhesive sheet obtained by the adjustment method described in 4.1.1 above was transferred to a 100 μm thick PET film to obtain an evaluation specimen.

  On the other hand, a glass plate having an arbitrary step on the surface is prepared to prepare an adherend for this test. In addition, the level | step difference provided on the glass plate in this test was formed by sticking the PET adhesive tape which has predetermined | prescribed fixed thickness on the surface of a glass plate. There are two types of PET adhesive tapes to be attached to the surface of the glass plate: 25 μm and 12.5 μm. That is, the surface of the glass plate is provided with two types of steps of 25 μm and 12.5 μm.

  50 μm-thick adhesive sheet transferred to a 100 μm-thick PET film, which is an evaluation test body, on the surface of a glass plate having an arbitrary step on the surface, which is an adherend for this test, by the above method Paste.

  Thereafter, autoclaving was performed under conditions of 50 ° C., 5 atm, and 20 minutes, and the filling of the step was visually observed. FIG. 4A is a diagram schematically showing that the pressure-sensitive adhesive sheet cannot fill a step on the glass plate, and voids and bubbles are visually recognized around the step. Moreover, FIG. 4B is a figure which shows typically that the adhesive sheet can fill the level | step difference on a glass plate, and the space | gap and air bubbles are not visually recognized around the level | step difference.

  As shown in FIG. 4A, since the adhesive sheet 230 transferred to the PET film 220 cannot follow the step 210 having the step d3 provided on the glass plate 250, there is a gap around the step 210. 240 or the gap 240 is visually recognized as bubbles. Further, as shown in FIG. 4B, when the adhesive sheet 230 transferred to the PET film 220 can follow the step 210 having the step d3 provided on the glass plate 250, the periphery of the step 210 The voids or voids are not visually recognized as bubbles.

  Based on the contents shown in FIGS. 4A and 4B, the step following property of the pressure-sensitive adhesive layer obtained from the pressure-sensitive adhesive composition was evaluated according to the following evaluation criteria.

(Evaluation)
○: A 50% step (that is, a 25 μm step) with an adhesive layer thickness of 50 μm can be filled, and voids and bubbles are not visually recognized around the step.
Δ: The first step of 25% with an adhesive layer thickness of 50 μm (that is, a step of 12.5 μm) can be filled, and no voids or bubbles are visible around the first step, but 50% of the adhesive layer thickness of 50 μm The second step (that is, a step of 25 μm) could not be filled, and voids and bubbles were visually recognized around the second step.
X: A 25% step (that is, a 25 μm step) with an adhesive layer thickness of 50 μm could not be filled, and voids and bubbles were visually recognized around the step.

4.2.3. 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). In addition, when a zipping phenomenon occurs at the time of peeling, it is described as “z” beside the adhesive force value in FIGS. 5A and 5B.

4.2.4. Using a weather-resistant 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)
○: Color difference ΔE * is 6.5 or less ×: Color difference ΔE * exceeds 6.5

The meanings of the abbreviations in FIGS. 5A and 5B are 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 block polymer (styrene content 30%)
(All of the above SEPS 1-3 and SEBS have a hydrogenation rate of 90% or more)
SIS: Styrene-isoprene-styrene block polymer SBS: Styrene-butadiene-styrene block polymer HV-300: Nisseki Polybutene HV-300 (manufactured by JX Nippon Mining & Energy Corporation)
TH130: YS Polystar TH130 (terpene phenol type tackifying resin, manufactured by Yasuhara Chemical Co., Ltd.)
P-100: Alcon P-100 (hydrogenated alicyclic saturated hydrocarbon resin, manufactured by Arakawa Chemical Co., Ltd.)
P-140: Alcon P-140 (hydrogenated alicyclic saturated hydrocarbon resin, manufactured by Arakawa Chemical Co., Ltd.)
Picolastic A5: (softening point 5 ° C., aromatic tackifying resin, manufactured by Eastman Chemical Co.)
Picotack 7050: (softening point 50 ° C., aromatic tackifying resin, manufactured by Eastman Chemical Co.)
Crystallex 3100: (softening point 100 ° C., aromatic tackifying resin, manufactured by Eastman Chemical Co.)

4.3. Evaluation Results From the evaluation results shown in FIG. 5A, the pressure-sensitive adhesive compositions of Examples 1 to 20 of the present application include (A) component, (B) component, and (C) component. The pressure-sensitive adhesive layer can have a relative dielectric constant of 1 to 3.5, and a pressure-sensitive adhesive layer excellent in step following ability can be obtained.

  On the other hand, as shown in FIG. 5B, Comparative Examples 1 to 4 use a component having a softening point of 140 ° C. corresponding to the component (C). It can be indirectly understood from the zipping phenomenon that occurred during the evaluation of adhesive strength that the layer becomes too hard.

  Moreover, since the composition of Comparative Examples 1-7 contains (C) component exceeding 50 mass parts with respect to 100 mass parts of (A) hydrogenated block copolymer, it may be inferior to level | step difference followability. Understandable.

  Moreover, since the composition of the comparative example 8 does not contain (C) component, the adhesive force of the adhesion layer obtained from this composition is a remarkably low thing. The compositions of Comparative Examples 9 and 10 contain the component (B) and a predetermined amount of the component (C) because the component (A) is not a hydrogenated block copolymer. The weather resistance of the adhesive layer is inferior.

  Moreover, since the composition of Comparative Example 11 used an aromatic tackifying resin having a softening point of 100 ° C. in place of the first compatibilizer having a softening point of 50 ° C. or lower, which is the component (B), the step following property was good. Can be understood as inferior.

  DESCRIPTION OF SYMBOLS 10,110 Liquid crystal display device (LCD), 11,15 Polarizing plate, 12, 14, 17 Adhesive layer, 13 Liquid crystal panel, 16 Anti-scattering film, 18 ITO layer, 19 Glass panel, 20, 120 Touch panel part, 21 Sensor Electrode, 30 adhesive layer, 40 cover glass, 41 printed layer, 100A, 100B, 100C, 200 touch panel type input / output device, 130 gap agent layer, 140 air layer, 210 step, 220 PET film, 230 adhesive sheet, 240 gap 250 glass plate.

Claims (15)

(A) a hydrogenated block copolymer;
(B) a first compatibilizer;
(C) a second compatibilizer;
An optical pressure-sensitive adhesive composition comprising:
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 50 ° C. or less.
The (C) second compatibilizer has a property compatible with the soft segment, and has a softening point of 50 ° C. or higher and lower than 140 ° C., and (A) 100 parts by mass of the hydrogenated block copolymer. 2 to 50 parts by mass,
An optical pressure-sensitive adhesive composition, wherein the pressure-sensitive adhesive layer obtained from the optical pressure-sensitive adhesive composition has a relative dielectric constant of 1 to 3.5.   2. The optical pressure-sensitive adhesive composition according to claim 1, wherein the content of the hard segment in the (A) hydrogenated block copolymer is 5 to 70 mass%.   The optical pressure-sensitive adhesive according to claim 1 or 2, wherein a 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. Agent composition.   4. The optical pressure-sensitive adhesive composition according to claim 1, wherein the (B) first compatibilizer is an aromatic tackifying resin. 5.   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. The optical material according to claim 4, which is at least one selected from the group consisting of styrene- (α-methylstyrene) -aliphatic hydrocarbon copolymer and styrene-aromatic hydrocarbon copolymer. Adhesive composition.   The optical according to any one of claims 1 to 5, wherein the (C) second compatibilizer is at least one selected from the group consisting of an alicyclic saturated hydrocarbon compound and a terpene phenol compound. 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.   The blending amount of the (B) first compatibilizer is 30 to 100 parts by mass with respect to 100 parts by mass of the (A) hydrogenated block copolymer, according to any one of claims 1 to 7. An optical pressure-sensitive adhesive composition.   9. The composition according to claim 1, wherein 5 to 55 parts by mass of the second compatibilizer is blended with respect to 30 to 80 parts by mass of the (B) first compatibilizer. An optical pressure-sensitive adhesive composition as described in 1. (D) a third compatibilizer that is compatible with the soft segment and is liquid at room temperature (23 ° C.),
10. The (D) third 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 9. Optical pressure-sensitive adhesive composition. 11. The adhesive layer according to claim 1, 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 Item.   The optical adhesive composition according to any one of claims 1 to 11, 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 12 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 12.   An input / output device comprising a pressure-sensitive adhesive layer formed using the optical pressure-sensitive adhesive composition according to claim 1.

Images