TWI611000B - Adhesive composition for optics,adhesive sheet,image displayer and input/output device - Google Patents

Abstract

The optical adhesive composition of the present invention is an optical adhesive composition comprising (A) a hydrogenated block copolymer, (B) a first compatibilizer, and (C) a second compatibilizer. (A) The 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 aforementioned (B) first compatibilizer has Compatible with the properties of the aforementioned hard segment, and the softening point is above 80 ° C; the aforementioned (C) second compatibilizer has properties compatible with the aforementioned soft segment, and is a liquid at normal temperature (23 ° C), obtained from the aforementioned optical The relative dielectric constant of the adhesive layer of the adhesive composition is 1 or more and 3.5 or less.

Description

Optical adhesive composition, optical adhesive sheet, image display device, and input / output device

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

In recent years, image display devices such as liquid crystal display devices, and input / output devices such as touch panels that can be used in combination with the image display devices have been widely used. In the manufacture of such image display devices and input / output devices, an adhesive composition is used when bonding the constituent members.

With the miniaturization of electronic parts constituting such image display devices and input / output devices, for example, high-frequency noise generated in a circuit, or electric charges contained in a dielectric body sandwiched by a conductive body during driving, are caused in electronic parts. Misoperation caused by noise generated in the internal circuit of the circuit cannot be ignored. In particular, in the case of an adhesive layer formed of an adhesive composition containing an acrylic adhesive as a main component, the relative dielectric constant is more than 4, and when an adhesive composition having such a relative dielectric constant is used, insulation is provided. The layer has a high electrostatic capacity, which can cause erroneous operation due to high-frequency noise.

For example, Patent Document 1 discloses an optical adhesive sheet for the purpose of preventing an erroneous operation of a capacitive touch panel type input / output device.

[Prior Art Document 1 [Patent Literature]

[Patent Document 1] International Publication No. WO2010 / 147047

The inventors of this case carefully reviewed related matters such as reducing the relative permittivity of the adhesive composition used in the manufacture of the image display device and the input / output device to prevent the erroneous operation of the image display device and the input / output device. It was found that an adhesive layer formed of an adhesive composition containing a specific material has a low relative dielectric constant, and has excellent durability, adhesion, and weather resistance.

The present invention provides an optical adhesive composition, an optical adhesive sheet formed using the optical adhesive composition, and an image display device and an output including an adhesive layer formed using the optical adhesive composition.入 装置。 Into the device. The above-mentioned optical adhesive composition can obtain an adhesive layer having a reduced relative dielectric constant and excellent durability, adhesion, and weather resistance.

1. An optical adhesive composition according to one aspect of the present invention, comprising: (A) a hydrogenated block copolymer, (B) a first compatibilizer, and (° C) a second compatibilizer, (A The 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. (C) The first compatibilizer (B) has the property of being compatible with the hard segment, and has a softening point of 80 ° C or higher; the (C) second compatibilizer has the property of being compatible with the soft segment, and It is a liquid at normal temperature (23 ° C.); the relative dielectric constant of the adhesive layer obtained from the aforementioned optical adhesive composition is 1 or more and 3.5 or less.

2. The optical adhesive composition according to the above 1, wherein the content of the hard segment of the (A) hydrogenated block copolymer may be 5 mass% or more and 70 mass% or less.

3. The optical adhesive composition according to the above 1 or 2, wherein the hydrogenation rate of the double bond contained in the polymer component of the conjugated diene monomer constituting the (A) hydrogenated block copolymer may be 90 %the above.

4. The optical adhesive composition according to any one of the above 1 to 3, wherein the (B) first compatibilizer may be an aromatic tackifying resin.

5. The optical adhesive composition according to the above 4, wherein the aromatic tackifier resin may be selected from the group consisting of an aromatic petroleum resin, a styrene polymer, an α-methylstyrene polymer, and benzene. Ethylene- (α-methylstyrene) -based copolymer, styrene-aliphatic hydrocarbon-based copolymer, styrene- (α-methylstyrene) -aliphatic hydrocarbon-based copolymer, and styrene-aromatic hydrocarbon-based At least one of the groups of the copolymer.

6. The optical adhesive composition according to any one of the above 1 to 5, wherein the (C) second compatibilizer may be selected from a polybutene-based compound, a polyisobutylene-based compound, and polyisoprene At least one of the groups of diene compounds.

7. The optical adhesive composition according to any one of 1 to 6 above. The acid value of the optical adhesive material composition may be 1 or less.

8. The optical adhesive composition according to any one of 1 to 7 above, wherein the content of the first (B) first compatibilizer may be 100% by mass based on the (A) hydrogenated block copolymer. It is 5 mass parts or more and 60 mass parts or less.

9. The optical adhesive composition according to any one of 1 to 8 above, wherein the content of the second compatibilizing agent (C) is 100% by mass based on the (A) hydrogenated block copolymer. It is 5 mass parts or more and 60 mass parts or less.

10. The optical adhesive composition according to any one of 1 to 9 above, wherein the (B) first compatibilizer and the ( C) The total content of the second compatibilizer may be 10 parts by mass or more and 80 parts by mass or less.

11. The optical 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 normal temperature (23 ° C). (D) The third compatibilizer may be a rosin-based tackifier resin, a terpene-based tackifier resin, or a hydrogenated alicyclic hydrocarbon resin.

12. The optical adhesive composition according to any one of 1 to 11 above, wherein the relative permittivity of the adhesive layer at a frequency of 1.0 × 10 ⁶ Hz may be a relative permittivity at a frequency of 1.0 × 10 ² Hz. More than 90% of the dielectric constant.

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

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

15. An image display device according to another aspect of the present invention includes: Those using the adhesive layer formed by the optical adhesive composition according to any one of 1 to 13 above.

16. Another input / output device according to the present invention includes an adhesive layer formed using the optical adhesive composition according to any one of 1 to 13 above.

Since the optical adhesive composition includes the component (A), the component (B), and the component (C), the relative dielectric constant of the adhesive layer from the optical adhesive composition is 1 or more and 3.5 or less. Therefore, it is possible to prevent erroneous operation caused by noise generated in the internal circuit included in the display device, or erroneous operation caused by the electric charge of the dielectric body sandwiched by the conductor, and durability and adhesion can be obtained. And an adhesive layer with excellent weather resistance. In addition, the image display device and the input / output device using the optical adhesive composition are adhesive layers having excellent durability, adhesion, and weather resistance, and can be prevented from being caused by noise generated in the internal circuit. Misoperation.

10.110‧‧‧Liquid crystal display (LCD)

11, 15‧‧‧ polarizing plates

12, 14, 17, 30‧‧‧‧ Adhesive layer

13‧‧‧LCD panel

16‧‧‧Prevents scattering film

18‧‧‧ITO layer

19‧‧‧ glass panel

20、120‧‧‧Touch Panel

100, 200‧‧‧ touch panel input / output device

130‧‧‧Interstitial agent layer

140‧‧‧Gap

FIG. 1 is a diagram illustrating the relationship between the relative dielectric constant and the frequency of the adhesive layer formed by the component (A) (hydrogenated block copolymer) constituting the adhesive composition of Example 1 of the present invention.

Fig. 2 is a schematic cross-sectional view showing the structure of an input / output device (a touch panel type input / output device) according to an embodiment of the present invention.

FIG. 3 is a schematic cross-sectional view showing a configuration of a known input / output device (a touch panel type input / output device).

Hereinafter, the present invention will be described in detail with reference to the drawings. In the present invention, unless otherwise specified, "part" means "mass part" and "%" means "mass%".

1. Adhesive composition for optics

An optical adhesive composition according to an embodiment of the present invention (hereinafter may be simply referred to as "adhesive composition"), which includes (A) a hydrogenated block copolymer (hereinafter also simply referred to as "(A) Component "), (B) the first compatibilizer (hereinafter also simply referred to as" (B) component "), (C) the second compatibilizer (hereinafter also simply referred to as" (C) Ingredients "). The relative dielectric constant of the adhesive layer obtained from the optical adhesive composition of this embodiment is 1 or more and 3.5 or less.

1.1. (A) Ingredient

(A) The hydrogenated (hydrogenated) block copolymer is a soft segment composed of a polymer component of an aromatic vinyl monomer and a soft component composed of a polymer component of a conjugated diene monomer. Thermoplastic elastomer. Among them, more specifically, the aromatic vinyl compound is preferably styrene or α-methylstyrene (more preferably, styrene), and the conjugated diene compound is butadiene or isoprene. Alkenes are preferred.

The adhesive layer formed by using the adhesive composition of this embodiment containing the component (A) has a lower relative dielectric constant than the adhesive layer formed of the adhesive composition containing an acrylic polymer. Characteristics (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 block copolymer (SEPS) (styrene-isoprene-styrene block copolymer (SIS) Hydride), styrene- (butadiene-butene) -styrene block copolymer (SBBS) hydride, styrene- (ethylene-butene) -styrene block copolymer (SEBS) (Hydride of styrene-butadiene-styrene block copolymer (SBS)), styrene- (ethylene-propylene) type block copolymer (SEP) (styrene-isoprene Type block copolymer (SI)), styrene- (ethylene-butene) type block copolymer (SEB) (styrene-butadiene type block copolymer (SB)) . Among them, from the viewpoint of excellent compatibility with the component (B), the component (A) is styrene- (ethylene-propylene) -styrene block copolymer (SEPS), styrene- (ethylene- ABA-type hydrogenated block copolymers such as butene) -styrene type block copolymer (SEBS) are particularly preferred. These systems can be used alone or in combination of two or more.

In the present invention, "compatible" or "compatibilizing" means that in a mixture obtained by mixing two different components, no turbidity or phase separation is visually recognized.

Among them, whether the component (B) is compatible with the hard segment constituting the (A) component is a component equivalent to the hard segment of the (A) component, that is, a polymer synthesized only from an aromatic vinyl monomer and (B) ) Ingredients.

More specifically, a polymer obtained by polymerizing only an aromatic vinyl monomer and the component (B) is mixed with a solvent as required. When the resulting mixture is not visually observed to be cloudy or contains the polymer, When the phase separated from the phase containing the component (B), the component (B) is considered to be compatible with the hard segment constituting the component (A); on the other hand, when the above turbidity or phase separation can be seen visually In this case, the component (B) is considered to be incompatible with the hard segment constituting the component (A).

(A) Ingredients can also use commercially available hydrogenated block copolymers, for example: SEP type septon 1001 and 1020, SEPS type septon 2002, 2004, 2005, 2006, 2007, 2063 and 2104, SEBS type septon 8004, 8006, 8007 , 8076 and 8104 (the aforementioned septon series are made by Kuraray), SEBS type tuftecH1221, H1662, H1052, H1053, H1041, H1051, H1517, H1043, H1272, and N504, SBBS type tuftecP1500, P2000, and JT83X (the above tuftec series are manufactured by Asahi Kasei Corporation).

From the viewpoint of imparting heat resistance to the adhesive composition of this embodiment, the content of the hard segment (for example, styrene) of the component (A) is preferably 5 mass% or more and 70 mass% or less, and more preferably 10 mass% or more. It is more preferably 60% by mass or less. (A) If the content of the hard segment of the component is less than 5% by mass, the heat resistance is poor. On the other hand, if it exceeds 70% by mass, the adhesive layer will become too hard and the adhesion with the adherend will be poor. Situation.

Furthermore, from the viewpoint of excellent compatibility with the component (C), the hydrogenation rate of the double bond contained in the polymer component of the conjugated diene monomer constituting the (A) component (hereinafter also referred to simply as "hydrogenation rate" ”), More preferably 90% or more, and more preferably 95% or more (Although the hydrogenation rate is preferably 100%, even a small amount of double bonds may be used). That is, in the present invention, the hydrogenation rate of the double bond contained in the polymer component of the conjugated diene monomer refers to the hydrogenation of the double bond contained in the polymer component of the conjugated diene monomer due to hydrogenation. proportion.

Among them, whether the (C) component is compatible with the soft segment constituting the (A) component is a component equivalent to the soft segment of the (A) component, that is, a polymer synthesized only from a conjugated diene monomer and ( C) Evaluation of ingredients.

More specifically, a polymer obtained by polymerizing only a conjugated diene monomer and the component (C) is mixed with a solvent as necessary. When the resulting mixture is not visually observed, turbidity or When phase separation occurs between the phase of the polymer body and the phase containing the (C) component, the (C) component is considered to be compatible with the soft segments constituting the (A) component. On the other hand, when the above is visually seen, When turbid or phase separated, it is regarded as (C) The composition is incompatible with the soft segments constituting the component (A).

In addition, from the viewpoint of preventing corrosion of the adherend, the acid value of the adhesive composition of this embodiment is preferably 1 or less.

The content of the component (A) of the adhesive composition of 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) ingredients

The first compatibilizer of the component (B) has a property of being compatible with the hard segment constituting the component (A), and the softening point is 80 ° C. or higher. Since the adhesive composition of this embodiment contains the component (B), and the component (B) is compatible with the hard segments constituting the component (A), the adhesive layer formed by the adhesive composition can be given a certain degree of The hardness can improve the adhesion to the adherend, and can improve the heat resistance of the adhesive layer.

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

From the viewpoint of improving the durability of the adhesive composition of this embodiment, improving the adhesion to the adherend, and improving the durability, the softening point of the component (B) may be 80 ° C or higher and 95 ° C or higher. The above is preferred, and more than 140 ° C is more preferred.

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

1.3. (C) Ingredients

The second compatibilizer of the component (C) is compatible with the soft segment constituting the component (A), and is a liquid at normal temperature (23 ° C). Moreover, the so-called "liquid" in the present invention also Including viscoelastic (viscoelastic) liquids, and other low viscosity liquids. Since the adhesive composition of this embodiment contains the component (C), and the component (C) is compatible with the soft segment constituting the component (A), the wettability of the adhesive layer is improved, and the result is possible. Improve durability. The component (C) may be, for example, a softening agent containing an aliphatic hydrocarbon such as a polybutene-based compound, a polyisobutylene-based compound, or a polyisoprene-based compound. It can be used as the softener of component (C), and it is also possible to use commercially available softeners. -35, HV-50, HV-100, HV-300, HV-1900, and SV-7000 (all manufactured by JX Nippon Nissei Energy Co., Ltd.), Tetrax 3T, 4T, 5T and 6T, Himol of polyisobutylene compounds 4H, 5H, 5.5H, and 6H (all manufactured by JX Nippon Steel and Nissho Energy Co., Ltd.), polyisoprene-based compounds Kuraprene LIR-290 (manufactured by Kuraray), and the like.

In the adhesive composition of this embodiment, the content of the component (C) is preferably 5 mass% or more and 35 mass% or less, and more preferably 10 mass% or more and 30 mass% or less. From the viewpoint of improving compatibility with the component (A), the content of the component (C) is preferably 5 mass parts or more and 60 mass parts or less with respect to 100 mass parts of the (A) component. More preferably, it is 10 mass parts or more and 55 mass parts or less. In addition, with respect to 100 parts by mass of the component (A), the total content of the components (B) and (C) is preferably 10 parts by mass or more and 80 parts by mass or less, and more preferably 15 parts by mass or more and 80 parts by mass or less. It is more preferable that it is 20 mass parts or more and 75 mass parts or less.

1.4. Relative permittivity

The relative dielectric constant of the adhesive layer obtained from the optical adhesive composition of this embodiment is a value of the relative dielectric constant measured at a frequency of 1.0 × 10 ² to 1.0 × 10 ⁶ Hz. The relative dielectric constant of the adhesive layer obtained from the optical adhesive composition of this embodiment is 1 or more and 3.5 or less, preferably 1 or more and 3.2 or less, and even more preferably 1 or more and 2.8 or less. The relative permittivity of the adhesive layer obtained from the adhesive composition for optics of this embodiment at a frequency of 1.0 × 10 ⁶ Hz may be more than 90% of the relative permittivity of the frequency of 1.0 × 10 ² Hz, and 95% The above is better. As mentioned, the relative permittivity of the adhesive layer at a frequency of 1.0 × 10 ⁶ Hz is more than 90% of the relative permittivity of the frequency of 1.0 × 10 ² Hz, so that the relative permittivity is stable in a wide frequency range. Therefore, it is possible to prevent erroneous operation caused by high-frequency pulses in an image display device or an input / output device provided with the adhesive layer.

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

1.5. (D) Ingredients

The third compatibilizer of the component (D) has a property of being at least compatible with the soft segment constituting the component (A), and is solid at normal temperature (23 ° C). The component (D) may be a rosin-based tackifying resin, a terpene-based tackifying resin, or a hydrogenated alicyclic hydrocarbon resin. (D) As a component, for example, KE311 (light-colored rosin-based tackifying resin, manufactured by Arakawa Chemical Co., Ltd.), TH130 (terpene phenol-based tackifying resin, manufactured by Yasuhara Chemical Co., Ltd.), and P-100 (hydrogenated alicyclic saturated hydrocarbon resin, Arakawa Chemical Co., Ltd.).

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

1.6. Uses

The optical adhesive composition of this embodiment can be used for bonding members constituting an image display device and an input / output device. A member to be bonded by using the optical adhesive composition of this embodiment, or an optical member (for example, selected from a polarizing film, a phase difference film, an elliptical polarizing film, an anti-reflection film, a brightness enhancement film, and light diffusion) Optical film in the group of film and hard coating film), metal layer such as ITO layer, or substrate made of glass or plastic. More specifically, the optical adhesive composition according to this embodiment is suitable for bonding members constituting a touch panel type input / output device.

An example in which the optical adhesive composition of the present embodiment is used for bonding members constituting a touch panel type input / output device will be described with reference to FIG. 2. FIG. 2 is a schematic cross-sectional view showing a configuration of an input / output device (a touch panel type input / output device 100) according to an embodiment of the present invention. The touch panel input / output device 100 according to this embodiment includes a liquid crystal display device (LCD) 10, a touch panel portion 20, and an adhesive layer 30 provided between the LCD 10 and the touch panel portion 20. The adhesive layer 30 is connected to the LCD 10 and the touch panel portion 20. The adhesive layer 30 is, for example, an optical adhesive composition of the present embodiment coated on the surface of a separator (not shown), dried, and the obtained adhesive sheet is peeled from the separator, and is provided on the LCD 10 and the touch panel. The control panel 20.

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 adhesive layer 12 is adjacent to the polarizing plate 11 and the liquid crystal panel 13, and the adhesive layer 14 is adjacent to the liquid crystal panel 13 and the polarizing plate 15.

Further, as shown in FIG. 2, the touch panel portion 20 is configured by stacking the explosion-proof film 16, the adhesive layer 17, the ITO layer 18, and the glass panel 19 in this order. sticky The coating layer 17 is adjacent to the explosion-proof film 16 and the ITO layer 18.

The adhesive layers 12, 14, and 17 are the same as the adhesive layer 30. The optical adhesive composition of this embodiment is applied to the surface of a separator (not shown) and dried, and the resulting adhesive sheet is self-divided. The separator is peeled and installed.

1.7. Effect

The optical adhesive composition of this embodiment includes the relative dielectric constant of the adhesive layer obtained from the optical adhesive composition by including the components (A), (B), and (C). It has a low relative permittivity adhesive layer of 1 to 3.5, so it can prevent erroneous operation caused by noise generated by the internal circuit contained in the display device.

In addition, the optical adhesive composition of this embodiment is improved by the component (B) being compatible with the hard segment constituting the component (A) and the component (C) being compatible with the soft segment constituting the (A) component. The wettability of the adherend can improve the durability. In addition, the optical adhesive composition of the present embodiment can improve durability (heat resistance) by including the (B) component having a softening point of 80 ° C. or higher.

More specifically, it is caused by the improvement of the wettability of the adherend due to the compatibility of the component (C) with the soft segments constituting the component (A), and the component (B) is a component with a high softening point. The interaction of the two, such as heat resistance improvement, can improve the durability of the adhesive layer. Thereby, an adhesive layer excellent in durability, adhesion, and weather resistance can be obtained.

In addition, the image display device and the input / output device using the optical adhesive composition of this embodiment can be adhered to an adherend such as a liquid crystal cell with a moderate adhesive force, and exhibit excellent durability, and can prevent Incorrect operation due to noise generated by internal circuits.

In particular, the optical adhesive composition of this embodiment is applicable to Bonding of components constituting a touch panel type input / output device.

1.7.1. Known structure of input / output device

The function and effect of the optical adhesive composition of this embodiment will be described more specifically, and the structure of a known input / output device will be described. FIG. 3 is a schematic cross-sectional view showing a configuration of a known input / output device (touch panel type input / output device 200). The touch panel input / output device 200 includes a liquid crystal display (LCD) 110 and a touch panel portion 120. Since an end portion between the LCD 110 and the touch panel portion 120 is provided with a gap filler layer 130, a gap 140 is generated between the gap filler layers 130 at both ends.

In recent years, a high-contrast display of a touch panel type input / output device is required. In order to achieve high contrast, for example, a method of filling the gap between the image display unit and the touch sensor (gap 140 in FIG. 3) with a transparent material such as an adhesive has been used in the past. Thereby, reflection or refraction of light between interfaces is suppressed, and as a result, high contrast can be achieved.

However, when the member 140 is filled with an adhesive or the like and the member is attached to the gap 140 in FIG. 3, the touch sensor may malfunction due to high-frequency noise generated by the internal circuit of the device or the charge of the member. For a touch panel input / output device that generates a gap between the image display and the touch sensor (especially a capacitive touch sensor), the relative dielectric coefficient of the air layer of the gap is 1, so it can be borrowed. A gap formed by the air layer blocks noise to prevent misoperation. On the other hand, when a transparent resin (such as an acrylic adhesive with a relative dielectric constant of 4 or more) is used as a filler to fill the gap between the image display portion and the touch sensor, high-frequency noise will propagate to the touch. Sensor, as a result, misoperation occurs. Although the driving frequency or the frequency of the noise are required to be different in order to prevent malfunction in a wide frequency range, the relative dielectric constant of the adhesive layer formed by using the acrylic adhesive has a frequency-dependent tilt. to.

For the reasons mentioned above, the touch panel type input / output device is ideally to use an adhesive layer with a low relative dielectric constant in a wide frequency domain to bury the gap between the image display portion and the touch sensor.

1.7.2. Effect of the invention

On the other hand, according to the optical adhesive composition according to this embodiment, it is possible to obtain an optical adhesive composition having a low relative permittivity (low relative frequency dependence of the relative permittivity) in a wide frequency range using the optical adhesive composition. The adhesive layer can prevent the malfunction of the touch sensor due to the high relative permittivity of the adhesive layer. That is, the gap 140 in FIG. 3 is filled with the optical adhesive composition of this embodiment, and an adhesive layer having a relative dielectric constant of 1 or more and 3.5 or less is provided in the gap 140 to prevent the touch sensor from being damaged. Misoperation.

For example, the touch panel type input / output device 100 of this embodiment shown in FIG. 2 is provided with an adhesive layer 30 between the LCD 10 and the touch panel portion 20, and the adhesive layer 30 is formed by the Those formed by the optical adhesive composition have a relative dielectric constant as low as 1 or more and 3.5 or less, so it can prevent misoperation of the touch sensor caused by the high relative permittivity of the adhesive layer.

In addition, the hydrogenated block copolymer of the component (A) is a thermoplastic having 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 elastic material is not only excellent in heat resistance due to the hard segment, but also prevents discoloration and modification due to the influence of coloring, ultraviolet rays, and the like due to the (A) component-based hydride, which results in excellent weather resistance. Therefore, it is possible to suppress the floating and peeling caused by the gas (water vapor, volatile components derived from the adherend) generated from the adherend under excessively severe conditions. Thereby, high quality and resistance Touch panel input / output device with excellent durability.

1.8. Other embodiments

The optical adhesive composition according to another embodiment of the present invention is an optical adhesive composition containing (i) a hydrogenated block copolymer, (ii) a first compatibilizer, and (iii) a second compatibilizer. The aforementioned (i) 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, and the aforementioned (ii) The first compatibilizer has properties compatible with the aforementioned hard segment, and (iii) the second compatibilizer has properties compatible with the aforementioned soft segment, and is derived from the relative of an adhesive layer composed of the aforementioned optical adhesive. The dielectric constant is 1 or more and 3.5 or less. Among them, the (i) hydrogenated block copolymer may use, for example, the component (A), the (ii) first compatibilizer may use, for example, the (B) component, and the (iii) second compatibilizer may, for example, use The component (C) and the component (D) (that is, a compatibilizer that is solid or liquid at ordinary temperature).

Since the optical adhesive composition contains the components (i), (ii) and (iii), the relative dielectric constant of the adhesive layer obtained from the optical adhesive composition is 1 or more and 3.5 or less, Therefore, it can prevent erroneous operation caused by noise generated by the internal circuit contained in the display device, erroneous operation caused by the charge of the dielectric body sandwiched by the conductor, and can obtain durability, adhesion and weather resistance. Excellent adhesive layer.

2. Adhesive sheet

The adhesive sheet of this embodiment can be obtained by coating the surface of a separator with the optical adhesive composition of this embodiment and drying it. More specifically, the method of gravure printing coater, meyer bar coater, air knife coater, and roll coater is applied to the substrate according to this embodiment. Adhesive composition, The applied adhesive composition is dried at normal temperature or by heating to produce an adhesive sheet according to this embodiment. The thickness of the adhesive sheet is usually in a range of 10 μm to 500 μm, and preferably in a range of 20 μm to 300 μm.

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 by using the optical adhesive composition of the present embodiment. Examples of the image display device in this embodiment include a liquid crystal display device.

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

(Example)

4. Examples

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

4.1. Preparation of adhesive composition

The ingredients shown in Tables 1 and 2 were mixed to prepare the adhesive compositions of Examples 1 to 21 and Comparative Examples 1 to 18, respectively. In addition, an adhesive sheet having a thickness of 50 μm used in an evaluation method described later was obtained by coating each adhesive composition on the surface of a separator and drying it.

4.2. Evaluation methods

4.2.1. Relative permittivity

An adhesive sheet having a thickness of 50 μm was attached to a copper foil having a thickness of 100 μm, and a copper foil having a thickness of 100 μm was attached as a measurement sample. Made by TOYO Corporation The LCR meter 6440B was connected to a copper foil, and the relative permittivity was calculated at 23 ° C and 65% RH. In addition, the results of the relative permittivity of the hydrogenated block copolymer constituting the adhesive composition of Example 1 are shown in Fig. 1 by changing the measurement frequency. For comparison, the acrylic polymer constituting the adhesive composition of Comparative Examples 13 and 17 was also measured in the same manner.

4.2.2. Heat-resistant foaming

The adhesive sheet having a thickness of 50 μm was transferred to a PET having a thickness of 100 μm, and was attached to Mitsubishi Resin Polycarbonate MR-58, and was left to stand in an environment of 85 ° C. and 85% RH. The appearance of the adhesive sheet was evaluated visually according to the following criteria.

(Evaluation)

◎: Abnormal appearance was not confirmed

○: 1 bubble with a diameter of 0.1 mm or less is recognized per 1 cm ²

△: 2 to 5 bubbles with a diameter of 0.1 mm or less or 1 or more bubbles with a diameter of 0.1 mm or less per 1.0 cm ²

×: 6 or more bubbles were confirmed per 1 cm ² , or bubbles exceeding 1.0 mm in diameter were recognized

4.2.3. Hot and humid whitening

An adhesive sheet having a thickness of 50 μm was transferred to a PET sheet having a thickness of 100 μm, and the sheet was attached to a glass plate, and left to stand in an environment of 60 ° C. and 95% RH. The moist heat whitening property was measured with a haze meter.

4.2.4. Evaluation of adhesion

The adhesive sheet with an adhesive layer thickness of 50 μm was cut into a 20-mm-wide short stick shape, the separator was peeled off, and then it was bonded to a glass substrate, and pressed back and forth 3 times with a 2 kg roller. After 20 minutes, peeling was performed at a peeling speed of 0.3 m / min and a peeling angle of 180 °, and this was measured. Adhesion at time (unit: N / 20mm).

4.2.5. Weatherability

A xenon weather meter was used to measure and compare the hue of the black panel before and after the test in which the temperature of the black panel was continuously lit in a light-dark cycle at a temperature of 63 ± 3 ° C.

(Evaluation)

◎: Color difference △ E * is 3.2 or less

○: Color difference △ E * is more than 3.2 and 6.5

△: Color difference △ E * is more than 6.5, 13.0 or less

×: Color difference ΔE * exceeds 13.0

The meanings of the abbreviations in Tables 1 and 2 are as follows.

SEPS1: styrene / ethylene-propylene / styrene block copolymer (hydrogenated styrene-isoprene-styrene block polymer; styrene content 13%)

SEPS2: styrene / ethylene-propylene / styrene block copolymer (hydrogenated styrene-isoprene-styrene block polymer; styrene content 20%)

SEPS3: styrene / ethylene-propylene / styrene block copolymer (hydrogenated styrene-isoprene-styrene block polymer; styrene content 65%)

SEBS: styrene / ethylene-butene / styrene block polymer (styrene content 30%) (also, the above-mentioned SEPS1, SEPS2, and SESP3 and SEBS hydrogenation rates are all above 90%)

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: ABA type triblock polymer of methyl methacrylate / n-butyl acrylate / methyl methacrylate = 6.5 / 87 / 6.5 (mass ratio)

FMR-0150: Aromatic Tackifying Resin with Softening Point of 145 ° C (Mitsui Chemical Co., Ltd.)

FTR-6100: Aromatic Tackifying Resin with Softening Point of 100 ° C (Mitsui Chemical Co., Ltd.)

Kristalex 3100: Aromatic tackifier resin with softening point of 100 ° C (manufactured by Eastman Chemical)

PiccolasticA5: Aromatic tackifier resin with softening point of 5 ° C (manufactured by Eastman Chemical)

DOP: Dioctyl phthalate (manufactured by Eastman Chemical)

KE311: Light-colored rosin based tackifying resin (manufactured by Arakawa Chemical Co., Ltd.)

TH130: terpene phenol type tackifying resin (manufactured by Yasuhara Chemical)

P-100: Hydrogenated alicyclic saturated hydrocarbon resin (manufactured by Arakawa Chemical Co., Ltd.)

4.3. Evaluation results

From the results in Table 1, it can be seen that the adhesive compositions of Examples 1 to 21 of the present case can include the adhesives obtained from the adhesive composition by including the components (A), (B), and (C). The relative dielectric constant of the layer is set to be 1 or more and 3.5 or less, and an adhesive layer having excellent durability (heat-resistant foaming property and wet heat whitening property) and weather resistance can be obtained.

On the other hand, as shown in Table 2, since the composition of Comparative Examples 1 to 5 in the present case does not contain the component (B), it can be understood that the durability (heat-resistant foaming property) is poor. In particular, Comparative Example 1 of the present case uses an aromatic tackifying resin having a softening point of less than 80 ° C to replace the first compatibilizer whose softening point of the component (B) is 80 ° C or higher, so it can be understood that the heat resistance is poor.

In addition, since the compositions of Comparative Examples 6 to 8 in the present case do not contain the (C) component, it can be understood that the durability (heat-resistant foaming property) is poor. In addition, since the composition of Comparative Examples 9 to 11 of this case uses an unhydrogenated block copolymer in place of the component (A), it can be understood that the weather resistance is poor. In addition, since the compositions of Comparative Examples 12 to 15, 17 and 18 of this case use acrylic polymers in place of the component (A), it can be understood that an adhesive layer having a high relative dielectric constant is obtained. In addition, since the composition of Comparative Example 16 of this case uses DOP (dioctyl phthalate) in place of the (C) component, it can be understood that the heat resistance is poor.

Moreover, according to FIG. 1, the adhesive layer formed from the adhesive composition of Example 1 has a relative dielectric constant that is stable in a wide frequency range. phase In this regard, the relative dielectric constant of the adhesive layer formed of the 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 adhesive composition of the present invention, an 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.

The drawings in this case are not enough to represent the optical adhesive composition requested in item 1 of the scope of patent application for this case, so there is no designated representative picture in this case.

Claims (14)

An optical adhesive composition comprising: (A) a hydrogenated block copolymer, (B) a first compatibilizer, (C) a second compatibilizer, and (D) a third compatibilizer; the aforementioned ( A) The 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 aforementioned (B) first is compatible The agent has the property of being compatible with the aforementioned hard segment, and has a softening point of 80 ° C or more; the aforementioned (C) second compatibilizer has the property of being compatible with the aforementioned soft segment, and is liquid at normal temperature (23 ° C); D) the third compatibilizer is compatible with the aforementioned soft segment and is solid at normal temperature (23 ° C), and is a rosin-based tackifier resin, a terpene-based tackifier resin, or a hydrogenated alicyclic hydrocarbon resin; The relative permittivity of the adhesive layer of the optical adhesive composition is 1 or more and 3.5 or less; the relative permittivity of the aforementioned adhesive layer at a frequency of 1.0 × 10 ⁶ Hz is the relative permittivity of the frequency at 1.0 × 10 ² Hz. More than 90%. The adhesive composition for optics according to item 1 of the scope of the patent application, wherein the content of the hard segment of the (A) hydrogenated block copolymer is 5 mass% to 70 mass%. The optical adhesive composition according to item 1 of the scope of patent application, wherein The hydrogenation rate of the double bond contained in the polymer component of the conjugated diene monomer forming the (A) hydrogenated block copolymer is 90% or more. The optical adhesive composition according to item 1 of the scope of patent application, wherein the (B) first compatibilizing agent is an aromatic tackifying resin. The optical adhesive composition according to item 4 of the scope of the patent application, wherein the aromatic tackifying resin is selected from the group consisting of aromatic petroleum resins, styrene polymers, α-methylstyrene polymers, Styrene- (α-methylstyrene) -based copolymer, styrene-aliphatic hydrocarbon-based copolymer, styrene- (α-methylstyrene) -aliphatic hydrocarbon-based copolymer, and styrene-aromatic hydrocarbon It is at least one of the groups of the copolymer. The optical adhesive composition according to item 1 of the scope of the patent application, wherein the (C) second compatibilizing agent is selected from the group consisting of polybutene-based compounds, polyisobutylene-based compounds, and polyisoprene-based compounds. At least one species in a group. The optical adhesive composition according to item 1 of the scope of the patent application, wherein the acid value of the optical adhesive composition is 1 or less. The adhesive composition for optics according to item 1 of the scope of patent application, wherein the content of the first compatibilizer in (B) is 5 parts by mass or more relative to 100 parts by mass of the (A) hydrogenated block copolymer. 60 parts by mass or less. The optical adhesive composition according to item 1 of the scope of the patent application, wherein the content of the second (C) second compatibilizer is 5 parts by mass or more based on 100 parts by mass of the (A) hydrogenated block copolymer. 60 parts by mass or less. The optical adhesive composition according to item 1 of the scope of the patent application, wherein the (B) first compatibilizer and the (C) second The total content of the compatibilizer is 10 parts by mass or more and 80 parts by mass the following. The optical adhesive composition according to item 1 of the scope of application for a patent is an adherent for a component constituting a touch panel type input / output device. An optical adhesive sheet is obtained by applying the optical adhesive composition according to any one of claims 1 to 10 on the surface of a separator and drying it. An image display device includes an adhesive layer formed by using the optical adhesive composition described in any one of claims 1 to 10 of the scope of patent application. An input / output device includes an adhesive layer formed using the optical adhesive composition described in any one of claims 1 to 10 of the scope of patent application.