Block copolymer, adhesive composition, adhesive sheet, and optical adhesive sheet

Abstract

The present invention relates to a block copolymer, an adhesive composition, an adhesive sheet and an optical adhesive sheet, and its purpose is to provide a block copolymer and an adhesive composition for an adhesive composition having sufficient transparency, a relative dielectric constant and a dielectric loss tangent, which can achieve excellent low dielectric properties. A block copolymer is a block copolymer for an adhesive composition, wherein the block copolymer comprises a polymer block (A) based on a vinyl aromatic monomer unit and a polymer block (B) based on a conjugated diene monomer unit, and the total content of Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, and Ni atoms is less than 400 mass ppm.

Description

Technical Field

[0001] The present invention relates to a block copolymer, an adhesive composition, an adhesive sheet, and an optical adhesive sheet. Background Art

[0002] Display devices such as liquid crystal displays are manufactured by laminating a plurality of optical components as materials, and a transparent tape (Optical Clear Adhesive: OCA) is used to bond these optical components together.

[0003] In the past, acrylic adhesives were primarily used as materials for OCA due to their transparency. For example, Patent Document 1 discloses an optical adhesive sheet using an acrylic adhesive for preventing operational malfunctions in capacitive touch panel input / output devices.

[0004] Furthermore, with the recent miniaturization of electronic components that make up displays and touch panels, noise generated within the internal circuits of these components, such as high-frequency noise generated within the circuits and charge trapped in dielectrics between conductors during operation, has become a problem. This noise can cause operational malfunctions within these circuits. Furthermore, with the increasing performance of information terminal devices and the rapid advancement of network technology, the electrical signals used in the information and communications field are becoming increasingly high-frequency, enabling high-speed and high-capacity transmission.

[0005] Against this backdrop, there is an increasing demand for lower dielectric constants in adhesives (including optical adhesives) in order to reduce operational errors in internal circuits or transmission losses.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: International Publication No. 2010 / 147047 Summary of the Invention

[0009] Problems to be solved by the invention

[0010] However, conventionally disclosed acrylic adhesives generally have a relative dielectric constant exceeding 3 and a dielectric loss tangent exceeding 0.05, and thus have a problem in that they are difficult to meet the above-mentioned demand for lower dielectric constants.

[0011] Adhesives using materials other than acrylic adhesives include, for example, rubber-based adhesives containing block copolymers. However, rubber-based adhesives do not yet have sufficient dielectric properties for practical use, and their transparency is also insufficient for practical use. Therefore, there is a problem that there is room for improvement in practical use for applications requiring low dielectric properties or OCA applications.

[0012] Therefore, in view of the above-mentioned problems of the prior art, the present invention aims to provide a block copolymer and an adhesive composition for providing an adhesive composition that achieves practically sufficient transparency and lower dielectric constant than conventionally disclosed acrylic adhesives.

[0013] Means for solving problems

[0014] The present inventors have conducted intensive studies to solve the above-mentioned problems and have found that the above-mentioned problems can be solved by limiting the content of specific atoms in a block copolymer having a specific structure, thereby completing the present invention.

[0015] That is, the present invention is as follows. [1]

[0017] A block copolymer, which is a block copolymer for an adhesive composition, wherein:

[0018] The block copolymer comprises a polymer block (A) mainly composed of vinyl aromatic monomer units and a polymer block (B) mainly composed of conjugated diene monomer units.

[0019] The total content of Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, and Ni atoms is 400 ppm by mass or less. [2]

[0021] The block copolymer according to the above [1], wherein the content of Ca atoms is 300 ppm by mass or less. [3]

[0023] The block copolymer according to the above-mentioned [1] or [2], wherein the content of Ca atoms is 50 ppm by mass or less. [4]

[0025] The block copolymer according to any one of the above-mentioned [1] to [3], wherein the total content of Li atoms and Ti atoms is 300 ppm by mass or less. [5]

[0027] The block copolymer according to any one of [1] to [4], wherein the hydrogenation rate of double bonds based on the conjugated diene monomer units in the block copolymer is 70% or more. [6]

[0029] The block copolymer according to any one of [1] to [5], wherein the block copolymer comprises:

[0030] 20% by mass or more and 90% by mass or less of component (I), and

[0031] 10% by mass or more and 80% by mass or less of component (II),

[0032] The component (I) is a block copolymer having one polymer block (A) mainly composed of vinyl aromatic monomer units and at least one polymer block (B) mainly composed of conjugated diene monomer units, and having a weight average molecular weight of 30,000 to 200,000.

[0033] The component (II) is a block copolymer containing at least one component selected from the group consisting of the following components (II-1), (II-2), and (II-3).

[0034] Component (II-1): a component having at least two polymer blocks (A) mainly composed of vinyl aromatic monomer units and at least one polymer block (B) mainly composed of conjugated diene monomer units, and having a weight average molecular weight that is 1.5 times or more and less than 2.5 times the weight average molecular weight of the above-mentioned component (I);

[0035] Component (II-2): a component having at least two polymer blocks (A) mainly composed of vinyl aromatic monomer units and at least one polymer block (B) mainly composed of conjugated diene monomer units, and having a weight average molecular weight that is 2.5 times or more and less than 3.5 times the weight average molecular weight of the above-mentioned component (I);

[0036] Component (II-3): A component having at least two polymer blocks (A) mainly composed of vinyl aromatic monomer units and at least one polymer block (B) mainly composed of conjugated diene monomer units, and having a weight average molecular weight that is 3.5 times or more and less than 4.5 times the weight average molecular weight of the above-mentioned component (I). [7]

[0038] The block copolymer according to any one of [1] to [6], wherein the block copolymer comprises a coupled polymer,

[0039] The coupled polymer contains a coupling agent residue containing an oxygen atom. [8]

[0041] The block copolymer according to [6] or [7], wherein the weight average molecular weight of the component (I) is 82,000 or more and less than 100,000. [9]

[0043] The block copolymer according to any one of the above-mentioned [1] to [8], wherein the content of the vinyl aromatic monomer unit is 5.0% by mass or more and 35.0% by mass or less.

[10]

[0045] An adhesive composition comprising:

[0046] 100 parts by mass of the block copolymer described in any one of [1] to [9] above, and

[0047] 1 to 250 parts by mass of a tackifier.

[11]

[0049] The adhesive composition as described in the above-mentioned

[10] further contains 120 parts by mass or less of a softener.

[12]

[0051] An optical adhesive composition comprising:

[0052] 100 parts by mass of the block copolymer described in any one of [1] to [9] above, and

[0053] 1 to 250 parts by mass of a tackifier.

[13]

[0055] The optical adhesive composition as described in the above-mentioned

[12] further contains 120 parts by mass or less of a softener.

[14]

[0057] An adhesive sheet having an adhesive layer composed of the optical adhesive composition according to

[12] or

[13] above.

[15]

[0059] An optical adhesive sheet for use as a device adhesive layer is used to form an electronic device having a display module, wherein the optical adhesive sheet has an adhesive layer composed of an optical adhesive composition.

[0060] The optical adhesive composition comprises:

[0061] 100 parts by mass of the block copolymer described in any one of [1] to [9] above, and

[0062] 1 to 250 parts by mass of a tackifier.

[16]

[0064] The optical adhesive sheet as described in

[15] above, wherein the device adhesive layer is provided between the transparent electrode and other transparent electrodes provided in the display module.

[17]

[0066] The optical adhesive sheet as described in

[15] or

[16] above further comprises a sensor layer constituting a touch sensor on the display surface side of the display module via the device adhesive layer.

[0067] The device adhesive layer is composed of the optical adhesive composition.

[18]

[0069] The optical adhesive sheet as described in any one of

[15] to

[17] above, wherein the display module comprises a liquid crystal panel, a polarizing plate, a light guide plate, and a light source,

[0070] A polarizing plate and a sensor layer constituting a touch sensor are provided on the display surface side of the display module via the device adhesive layer.

[0071] The sensor layer and the glass cover are laminated via another device adhesive layer.

[0072] The device adhesive layer is a layer adjacent to the polarizer.

[0073] The other device adhesive layer is a layer adjacent to the sensor layer.

[0074] Effects of the Invention

[0075] According to the present invention, a block copolymer for an adhesive composition having practically sufficient transparency, small relative dielectric constant and dielectric loss tangent values, and capable of achieving excellent lowering of dielectric constant, and an adhesive composition can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] Figure 1 This figure shows an example of vertical segmentation at the inflection point between peaks in the GPC curve of the block copolymer of the present invention.

[0077] Figure 2 A schematic cross-sectional view showing an example of an electronic device using the optical adhesive sheet of the present invention for an adhesive layer.

[0078] Figure 3 A schematic cross-sectional view showing another example of an electronic device using the optical adhesive sheet of the present invention for an adhesive layer.

[0079] Figure 4 A schematic cross-sectional view showing another example of an electronic device using the optical adhesive sheet of the present invention for an adhesive layer.

[0080] Figure 5 A schematic cross-sectional view showing another example of an electronic device using the optical adhesive sheet of the present invention for an adhesive layer.

[0081] Figure 6 A schematic cross-sectional view showing another example of an electronic device using the optical adhesive sheet of the present invention for an adhesive layer.

[0082] Explanation of symbols

[0083] 1Device adhesive layer

[0084] 2 cover glass

[0085] 3 display module

[0086] 4 functional layers

[0087] 5Sensor layer (touch sensor)

[0088] 6 Transparent electrode

[0089] 7 polarizers

[0090] 8 LCD panels

[0091] 9 Light guide plate

[0092] 10 Electronic devices

[0093] 11 Light Source DETAILED DESCRIPTION

[0094] A specific embodiment of the present invention (hereinafter referred to as "this embodiment") will be described in detail below.

[0095] It should be noted that the following embodiments are examples for explaining the present invention and are not intended to limit the present invention to the following contents. The present invention can be implemented with various modifications within the scope of the gist of the present invention.

[0096] [Block copolymer]

[0097] The block copolymer of this embodiment is a block copolymer for an adhesive composition, which includes a polymer block (A) mainly composed of vinyl aromatic monomer units and a polymer block (B) mainly composed of conjugated diene monomer units, and the total content of Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, and Ni atoms is not more than 400 mass ppm.

[0098] The block copolymer of the present embodiment, having the above-mentioned structure, has sufficient transparency for practical use as an adhesive composition, and has lower relative dielectric constant and dielectric loss tangent values ​​than conventionally known acrylic adhesives, thereby achieving excellent low dielectric constant.

[0099] The “vinyl aromatic monomer unit” refers to a structure that is a polymer constituent obtained by polymerizing a vinyl aromatic compound, and the “conjugated diene monomer unit” refers to a structure that is a polymer constituent obtained by polymerizing a conjugated diene compound.

[0100] The “polymer block (A) mainly composed of vinyl aromatic monomer units” refers to a polymer block containing 80% by mass or more, preferably 85% by mass or more, more preferably 95% by mass or more of vinyl aromatic monomer units.

[0101] Furthermore, the “polymer block (B) mainly composed of conjugated diene monomer units” refers to a polymer block containing more than 70% by mass, preferably 85% by mass or more, more preferably 95% by mass or more of conjugated diene monomer units.

[0102] Examples of the vinyl aromatic compound used to form the vinyl aromatic monomer units constituting the polymer blocks include, but are not limited to, alkyl styrenes such as styrene, α-methylstyrene, p-methylstyrene, and p-tert-butylstyrene; alkoxystyrenes such as p-methoxystyrene; and vinylnaphthalene. Styrene is particularly preferred. The vinyl aromatic compound may be used alone or in combination of two or more.

[0103] The conjugated diene compound for forming the conjugated diene monomer unit constituting the polymer block can be a diene with a conjugated double bond, and can include but is not limited to 1,3-butadiene, 2-methyl-1,3-butadiene (isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, etc. 1,3-butadiene and isoprene are particularly preferred. In addition, by using 1,3-butadiene, there is a tendency to obtain a block copolymer and an adhesive composition having excellent heat aging resistance and light resistance, and thus it is more preferred. One conjugated diene compound can be used alone, or two or more can be used in combination.

[0104] In the block copolymer of the present embodiment, the total content of Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, and Ni atoms is 400 ppm by mass or less.

[0105] The block copolymer of the present embodiment, by possessing the above-mentioned formation, has the tendency of obtaining the improvement effect of transparency in the adhesive composition comprising a solvent and the adhesive film after being coated and dried, has the tendency that the value of relative dielectric constant and dielectric loss tangent fully becomes smaller than acrylic adhesive, thus preferably.The adhesive composition of rubber system is diluted with the organic solvent that can dissolve block copolymer, but when the block copolymer contains the above-mentioned atoms or the compound comprising the above-mentioned atoms, they are not dissolved in the solvent and generate agglomerates, scatter light, and cause transparency to reduce.From this aspect, in the block copolymer of the present embodiment, the content of Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, Ni atoms is made to add up to 400 mass ppm or less, preferably 360 mass ppm or less, more preferably 340 mass ppm or less, further preferably 300 mass ppm or less.

[0106] Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, and Ni atoms can be mixed in from polymerization initiators, hydrogenation catalysts, coupling agents, process additives, anti-blocking agents, monomer impurities, impurities in solvents or water, and production equipment used in the polymerization of block copolymers.

[0107] Therefore, by reducing the mixing from them, the total content of Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, and Ni atoms can be controlled to the above-mentioned numerical range.

[0108] In particular, anti-blocking agents such as metal soap-based anti-blocking agents containing Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, and Ni atoms as counter cations tend to have a greater effect on the transparency of the adhesive composition due to the large molecular weight of the anti-blocking agent and the large size of the aggregates when Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, and Ni atoms are contained in the block copolymer.

[0109] Therefore, in the block copolymer of this embodiment, the content of the anti-blocking agent containing Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, and Ni atoms is preferably 1000 ppm or less, more preferably 500 ppm or less, even more preferably 300 ppm or less, and even more preferably substantially free of these atoms. The term "substantially free" means that an anti-blocking agent containing Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, or Ni atoms as a main raw material, such as a metal soap, is not actively added, and the use of an anti-blocking agent containing Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, or Ni atoms as impurities is not excluded.

[0110] The anti-blocking agent included in the block copolymer of the present embodiment is unrestricted as long as it is soluble in a solvent. However, the type of anti-blocking agent soluble in a solvent is limited, so substantially not including an anti-blocking agent is also one of preferred modes. This "substantially not including" refers to not actively adding, but also does not exclude the amount of the degree mixed into the production plant or material etc. with an unavoidable degree.

[0111] In addition, in the case of using toluene or ethyl acetate as solvent in the adhesive composition containing the block copolymer of the present embodiment, if block copolymer includes Ca atoms, there is a particularly large tendency for the impact produced on transparency. Therefore, the content of the Ca atoms in the block copolymer of the present embodiment is preferably below 300 mass ppm, more preferably below 200 mass ppm, further preferably below 100 mass ppm, further preferably below 50 mass ppm, more preferably below 30 mass ppm. In addition, in the case where block copolymer includes Ca atoms, there is a particularly large tendency for the impact produced on dielectric loss tangent. From this aspect, the content of the Ca atoms in the block copolymer of the present embodiment is also preferably below 30ppm.

[0112] Many Ca atoms originate from the anti-blocking agent and are mixed into the block copolymer. By selecting an appropriate anti-blocking agent, the content can be controlled within the above range.

[0113] In addition, when Li atoms and Ti atoms are included in the block copolymer, there is also a tendency to have a significant impact on transparency. Therefore, the total content of Li atoms and Ti atoms in the block copolymer of this embodiment is preferably 300 mass ppm or less, more preferably 250 mass ppm or less, further preferably 130 mass ppm or less, and even more preferably 50 mass ppm or less.

[0114] In addition, when Li atoms and Ti atoms are included in the block copolymer, there is a large tendency for the influence produced on dielectric loss tangent. From this aspect, the total of the content of the Li atoms and Ti atoms in the block copolymer of the present embodiment is also preferably less than 300 mass ppm, more preferably less than 250 mass ppm, further preferably less than 130 mass ppm, and further preferably less than 50 mass ppm. Li atoms are mostly mixed in from polymerization initiator, and Ti atoms are mostly mixed in from hydrogenation catalyst, by reducing the addition amount during polymerization as much as possible, and carrying out known deashing after polymerization, it is possible to control their content within the above range.

[0115] The contents of Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, and Ni atoms in the block copolymer can be measured by the method described in the Examples below.

[0116] The content of the vinyl aromatic monomer unit in the block copolymer of the present embodiment is preferably 35.0 mass % or less, more preferably 30.0 mass % or less, further preferably 25.0 mass % or less, still more preferably 20.0 mass % or less, and still more preferably 15.0 mass % or less.

[0117] By setting the content of the vinyl aromatic monomer units in the block copolymer of this embodiment within the above range, the relative dielectric constant and dielectric loss tangent tend to be reduced. In addition, when formed into an adhesive sheet, an adhesive sheet that is less likely to be necked tends to be obtained.

[0118] The content of the vinyl aromatic monomer unit in the block copolymer of the present embodiment is preferably 5.0% by mass or more, more preferably 7.0% by mass or more, even more preferably 9.0% by mass or more, and even more preferably 10.0% by mass or more.

[0119] By making the content of the vinyl aromatic monomer unit in the block copolymer of the present embodiment be 5.0% by mass or more, there is a tendency for heat resistance and foaming to be improved. In this specification, "heat resistance and foaming" refers to an index indicating the difficulty of bubble generation after heating under the conditions of 85°C and 85% RH. Devices such as smart phones that use adhesive compositions in the adhesive layer are sometimes exposed to high temperatures during use. Therefore, in order to maintain performance even when exposed to high temperatures, it is necessary for the adhesive layer not to generate bubbles. Among them, regarding the conditions of 85°C and 85% RH, due to strict accelerated tests, it is not required that bubbles are not generated at all, and the practical characteristics of heat resistance and foaming are relatively judged based on the number of bubbles generated under the above-mentioned accelerated tests.

[0120] The content of the vinyl aromatic monomer unit in the block copolymer of the present embodiment can be controlled to fall within the above-mentioned numerical range by adjusting the amount of monomer added in the polymerization step.

[0121] The hydrogenation rate of double bonds based on the conjugated diene monomer units in the block copolymer of the present embodiment is preferably 70% or more, more preferably 80% or more, further preferably 85% or more, and even more preferably 90% or more.

[0122] When the hydrogenation rate of the double bonds based on the conjugated diene monomer units in the block copolymer of this embodiment is within the above range, the relative dielectric constant and dielectric loss tangent tend to decrease, and the weather resistance and heat resistance tend to improve.

[0123] The hydrogenation rate can be controlled to fall within the above-mentioned desired numerical range by adjusting the amount of hydrogenation relative to the block copolymer, the conditions such as temperature and pressure in the hydrogenation step, and the type and amount of the hydrogenation catalyst added.

[0124] In addition, from the perspective of weather resistance and heat resistance, a hydrogenated block copolymer using styrene as a vinyl aromatic monomer unit and butadiene as a conjugated diene monomer unit (SEBS) is more preferable than a hydrogenated block copolymer using styrene as a vinyl aromatic monomer unit and isoprene as a conjugated diene monomer unit (SEPS).

[0125] When the block copolymer of this embodiment is a hydrogenated block copolymer, the vinyl bond content of the conjugated diene monomer units in the block copolymer before hydrogenation is preferably 20% or more, more preferably 25% or more, and even more preferably 30% or more. By setting the vinyl bond content of the conjugated diene monomer units in the block copolymer before hydrogenation within the above range, crystallization of the hydrogenated portion is suppressed, which tends to facilitate handling.

[0126] Furthermore, the conjugated diene monomer units of the block copolymer of this embodiment have a vinyl bond content before hydrogenation of preferably 65% ​​or less, more preferably 60% or less, even more preferably 55% or less, still more preferably 50% or less, and even more preferably 48% or less. By setting the vinyl bond content of the conjugated diene monomer units of the block copolymer before hydrogenation within the above range, weather resistance and heat resistance tend to be improved.

[0127] In order to adjust the vinyl bond content of the conjugated diene monomer units in the block copolymer, for example, it is effective to use ethers or tertiary amines as a vinyl bond content adjuster. Specifically, one or a mixture of two or more selected from ethylene glycol dimethyl ether, tetrahydrofuran, α-methoxytetrahydrofuran, N,N,N',N'-tetramethylethylenediamine, etc. is used. These are preferably added to the polymerization solvent at a stage before adding the conjugated diene monomer.

[0128] The content of the vinyl aromatic monomer units in the block copolymer, the amount of vinyl bonds in the conjugated diene monomer units before hydrogenation, and the hydrogenation rate of the vinyl bonds in the conjugated diene monomer units before hydrogenation can be determined by NMR measurement of the hydrogenated block copolymer. Specifically, they can be measured by the method described in the Examples below.

[0129] The block copolymer preferably contains 20% to 90% by mass of component (I) and 10% to 80% by mass of component (II), wherein the component (I) is a block copolymer having one polymer block (A) mainly composed of vinyl aromatic monomer units and at least one polymer block (B) mainly composed of conjugated diene monomer units, and having a weight-average molecular weight of 30,000 to 200,000, and the component (II) comprises at least one component selected from the group consisting of the following components (II-1), (II-2) and (II-3).

[0130] Component (II-1): a component having at least two polymer blocks (A) mainly composed of vinyl aromatic monomer units and at least one polymer block (B) mainly composed of conjugated diene monomer units, and having a weight average molecular weight that is 1.5 times or more and less than 2.5 times the weight average molecular weight of the above-mentioned component (I);

[0131] Component (II-2): a component having at least two polymer blocks (A) mainly composed of vinyl aromatic monomer units and at least one polymer block (B) mainly composed of conjugated diene monomer units, and having a weight average molecular weight that is 2.5 times or more and less than 3.5 times the weight average molecular weight of the above-mentioned component (I);

[0132] Component (II-3): A component having at least two polymer blocks (A) mainly composed of vinyl aromatic monomer units and at least one polymer block (B) mainly composed of conjugated diene monomer units, and having a weight average molecular weight that is 3.5 times or more and less than 4.5 times the weight average molecular weight of the above-mentioned component (I).

[0133] The block copolymer of the present embodiment tends to have an improved balance between viscosity and adhesive force due to the aforementioned configuration.

[0134] The content of component (I) in the block copolymer of the present embodiment is preferably 20% by mass or more, more preferably 30% by mass or more, further preferably 35% by mass or more, still more preferably 45% by mass or more, and still more preferably 55% by mass or more. By setting the content of component (I) in the block copolymer of the present embodiment within the above range, the viscosity tends to be lower.

[0135] By making the block copolymer have a low viscosity, the organic solvent is easily evaporated during the drying process of manufacturing an adhesive sheet in which the adhesive layer is formed from the adhesive composition containing the block copolymer, thereby reducing the amount of organic solvent remaining in the adhesive sheet. Therefore, even if the device temperature rises during the manufacturing process or during use of the device in which the adhesive sheet is used to bond the layers together, bubbles from the organic solvent tend to be less likely to form in the adhesive sheet.

[0136] In addition, the content of component (I) in the block copolymer of the present embodiment is preferably 90% by mass or less, more preferably 80% by mass or less, further preferably 75% by mass or less, and even more preferably 70% by mass or less. By making the content of component (I) in the block copolymer within the above range, there is a tendency to improve heat-resistant foaming properties.

[0137] The content of component (II) in the block copolymer of the present embodiment is preferably 10% by mass or more, more preferably 20% by mass or more, further preferably 25% by mass or more, and even more preferably 30% by mass or more. By making the content of component (II) in the block copolymer of the present embodiment within the above range, there is a tendency for heat-resistant foaming to be improved.

[0138] In the state that the adhesive composition including block copolymer is used as adhesive layer, if electronic device is exposed to high temperature and high humidity conditions, there is the tendency that the winding of polymer straight chain weakens.In the case where moisture enters its gap, it is possible to produce bubbles from water, but by including therein a polymer with spherical side chains (more than 3 branches), there is the tendency that moisture can be suppressed from immersing, suppressing the bubbles from moisture. However, as described later, if including a polymer with side chains, an increase in viscosity will occur, so that an organic solvent is difficult to evaporate, thus setting a preferred upper limit to the amount of the component (II) as a branched polymer.

[0139] From the above aspects, the content of component (II) in the block copolymer of the present embodiment is preferably 80% by mass or less, more preferably 70% by mass or less, further preferably 65% ​​by mass or less, and further preferably 55% by mass or less. By making the content of component (II) in the above block copolymer within the above range, the block copolymer and adhesive composition of the present embodiment have a tendency to have a lower viscosity.

[0140] The weight average molecular weight of the component (I) is preferably 30,000 or more, more preferably 40,000 or more, even more preferably 50,000 or more, still more preferably 60,000 or more, even more preferably 70,000 or more, and particularly preferably 82,000 or more. When the weight average molecular weight of the component (I) is within the above range, the heat-resistant foaming properties of the block copolymer and the adhesive composition of this embodiment tend to be improved.

[0141] In addition, the weight average molecular weight of the above-mentioned component (I) is preferably less than 200000, more preferably less than 180000, further preferably less than 160000, and then more preferably less than 140000, further preferably less than 120000, particularly preferably less than 100000. By making the weight average molecular weight of the above-mentioned component (I) in the above range, there is a tendency for the viscosity of the block copolymer and the adhesive composition of the present embodiment to decrease. Especially by being more than 82000 and less than 100000, there is a tendency for the heat-resistant foaming property when the block copolymer of the present embodiment is made low in dielectric and the balance of viscosity to be excellent.

[0142] In the block copolymer of the present embodiment, above-mentioned component (II) can only include 1 kind in above-mentioned component (II-1), component (II-2) and component (II-3), or can include more than 2 kinds.In the case of including more than 2 kinds in these, the content of preferred component (II-2) is more than the content of component (II-1).In addition, the content of preferred component (II-3) is more than the content of component (II-1).By taking such formation, the block copolymer of the present embodiment and adhesive composition have the tendency that the balance of viscosity and adhesion further improves.

[0143] The fact that component (II-1), component (II-2) and component (II-3) are contained as component (II) in the block copolymer of this embodiment can be determined by the difference in the peak position of the molecular weight distribution curve of gel permeation chromatography (hereinafter also referred to as "GPC") under the specified conditions shown below.

[0144] That is, in the GPC chart, by confirming the peak at 1.5 times or more and less than 2.5 times the weight average molecular weight of component (I) (component (II-1)), the peak at 2.5 times or more and less than 3.5 times the weight average molecular weight of component (I) (component (II-2)), and the peak at 3.5 times or more and less than 4.5 times the weight average molecular weight of component (I) (component (II-3)), it is possible to confirm the component (II-1), component (II-2), and component (II-3) contained in the block copolymer of the present embodiment.

[0145] In addition, about the area ratio of component (II-1), component (II-2) and component (II-3) to the total area of ​​component (II), it can be determined by performing GPC measurement according to the apparatus (ACQUITY APC system) and conditions described in the examples described later, and then performing vertical segmentation of the inflection points between the peaks of the GPC curve to the baseline using the system / software described in the same example. Here, the inflection points between the peaks of component (II-1), component (II-2) and component (II-3) refer to the lowest point (bottom) between adjacent peaks in the vertical direction. In addition, when the lowest point continues, it is the middle point. Using the above-mentioned inflection points, vertical segmentation is performed using the specified waveform separation software, and after segmentation, calculation of each weight-average molecular weight and calculation of the area ratio are performed. The inflection points between the peaks of component (II-1), component (II-2) and component (II-3) are obtained and the inflection points are vertically segmented. An example of the figure is shown in Figure 1 .

[0146] The contents and weight average molecular weight of component (I), component (II), component (II-1), component (II-2), and component (II-3) in the block copolymer of this embodiment can be measured by the methods described in the examples below.

[0147] From the perspective of viscosity, the weight average molecular weight of the block copolymer of this embodiment is preferably 300,000 or less, more preferably 260,000 or less, and even more preferably 230,000 or less. From the perspective of heat-resistant foaming, it is preferably 110,000 or more, more preferably 130,000 or more, and even more preferably 150,000 or more.

[0148] Polymer solution viscosity is not only an indicator of viscosity but also an indicator of heat-resistant foaming properties. The toluene solution viscosity of the block copolymer of this embodiment is preferably 10 mPa·s or greater, more preferably 50 mPa·s or greater, and even more preferably 100 mPa·s or greater. By falling within this numerical range, the heat-resistant foaming properties of the block copolymer and adhesive composition of this embodiment tend to be improved.

[0149] The block copolymer of this embodiment preferably includes a coupling polymer, and the coupling polymer includes a coupling agent residue containing an oxygen atom.

[0150] By adopting the above-mentioned structure, the metal atom-containing compound remaining in the block copolymer interacts with the oxygen atoms, making it difficult for the metal atom-containing compound to diffuse in the solvent and less likely to generate fine particles that reduce transparency. Therefore, the transparency of the adhesive composition prepared by containing a solvent tends to be improved.

[0151] In addition, it is preferred that the block copolymer before coupling is the above-mentioned component (I), and the coupled polymer after coupling is the above-mentioned component (II).

[0152] [Method for producing block copolymer]

[0153] (Polymerization step and coupling step)

[0154] As a method for producing the block copolymer of the present embodiment, for example, a method comprising the following steps: a polymerization step in which a vinyl aromatic compound such as styrene and a conjugated diene compound such as butadiene are copolymerized in an inert hydrocarbon solvent using an organic lithium compound as a polymerization initiator to obtain a block copolymer; and a coupling step in which the obtained block copolymer is reacted with a coupling agent to obtain the above-mentioned components (I) and (II).

[0155] In this case, the coupled block copolymer becomes the above-mentioned component (II), and the uncoupled and residual block copolymer becomes the above-mentioned component (I). It should be noted that by controlling the addition amount of the coupling agent in the coupling reaction, the contents of the above-mentioned components (I) and (II) can be adjusted to the above-mentioned specific ranges.

[0156] The weight average molecular weight of components (I) and (II) can be controlled by adjusting the amount of a polymerization initiator such as an organic lithium compound.

[0157] After the polymerization reaction is completed, a coupling reaction is performed, and water, alcohol, acid, etc. are added to deactivate the active species. Thereafter, the polymerization solvent is separated by, for example, steam stripping, and then dried to obtain the block copolymer of this embodiment containing the above components (I) and (II).

[0158] As the polymerization method of each block copolymer of component (I) and component (II), it is not particularly limited, and the polymerization methods such as coordination polymerization, anionic polymerization or cationic polymerization can be enumerated. Among these, from the aspect of the easiness of structural control, it is preferred that anionic polymerization. As the manufacture method of the block copolymer composition utilizing anionic polymerization, it is possible to use known methods, which are not particularly limited, and the method of recording in Japanese Patent Publication No. 36-19286, Japanese Patent Publication No. 43-17979, Japanese Patent Publication No. 46-32415, Japanese Patent Publication No. 49-36975, Japanese Patent Publication No. 48-2423, Japanese Patent Publication No. 48-4106, Japanese Patent Publication No. 56-28925, Japanese Patent Publication No. 59-166518, Japanese Patent Publication No. 60-186577 etc. can be enumerated.

[0159] Examples of the inert hydrocarbon solvent used in the polymerization step of the block copolymer of this embodiment include, but are not limited to, aliphatic hydrocarbons such as butane, pentane, hexane, isopentane, heptane, octane, and isooctane; alicyclic hydrocarbons such as cyclopentane, methylcyclopentane, cyclohexane, methylcyclohexane, and ethylcyclohexane; and aromatic hydrocarbons such as benzene, toluene, ethylbenzene, and xylene. These hydrocarbon solvents may be used alone or in combination of two or more.

[0160] In addition, examples of the organolithium compound used as a polymerization initiator in the polymerization step of the block copolymer of this embodiment include, but are not limited to, ethyllithium, propyllithium, n-butyllithium, sec-butyllithium, tert-butyllithium, phenyllithium, propenyllithium, and hexyllithium. n-Butyllithium and sec-butyllithium are particularly preferred. The organolithium compound may be used alone or as a mixture of two or more.

[0161] As the coupling agent for obtaining the multibranched block copolymer, a known coupling agent can be used.

[0162] The bifunctional coupling agent is not particularly limited, and examples thereof include bifunctional halogenated silanes such as dichlorosilane, monomethyldichlorosilane, and dimethyldichlorosilane; bifunctional alkoxysilanes such as diphenyldimethoxysilane, diphenyldiethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane; bifunctional halogenated alkanes such as dichloroethane, dibromoethane, dichloromethane, and dibromomethane; bifunctional tin halides such as tin dichloride, monomethyltin dichloride, dimethyltin dichloride, monoethyltin dichloride, diethyltin dichloride, monobutyltin dichloride, and dibutyltin dichloride; dibromobenzene, benzoic acid, CO, and 2-chloropropylene.

[0163] The trifunctional coupling agent is not particularly limited, and examples thereof include trifunctional halogenated alkanes such as trichloroethane and trichloropropane; trifunctional halogenated silanes such as methyltrichlorosilane and ethyltrichlorosilane; and trifunctional alkoxysilanes such as methyltrimethoxysilane, phenyltrimethoxysilane and phenyltriethoxysilane.

[0164] The tetrafunctional coupling agent is not particularly limited, and examples thereof include tetrafunctional halogenated alkanes such as carbon tetrachloride, carbon tetrabromide, and tetrachloroethane; tetrafunctional halogenated silanes such as tetrachlorosilane and tetrabromosilane; tetrafunctional alkoxysilanes such as tetramethoxysilane and tetraethoxysilane; and tetrafunctional tin compounds such as tetrachlorotin, tetrabromotin, and tetrabutyltin.

[0165] The pentafunctional or higher-functional coupling agent is not particularly limited, but examples thereof include 1,1,1,2,2-pentachloroethane, perchloroethane, pentachlorobenzene, perchlorobenzene, octabromodiphenyl ether, and decabromodiphenyl ether. In addition, epoxidized soybean oil, di- to hexafunctional epoxy-containing compounds, carboxylic acid esters, and polyvinyl compounds such as divinylbenzene can also be used. Coupling agents may be used alone or in combination of two or more.

[0166] Among these, tetramethoxysilane and tetraethoxysilane are particularly preferred.

[0167] The area ratio of the component (II-1), component (II-2), and component (II-3) in the GPC elution curve of the above-mentioned component (II) constituting the block copolymer of the present embodiment can be controlled by the amount of coupling agent added, temperature, and time in the coupling reaction as described above. Specifically, when the coupling agent is an alkoxysilane compound, the following method can be cited: the time from the time the reaction temperature reaches the maximum temperature to the time the coupling agent is added is set to 1 minute to 30 minutes, the reaction time of the coupling agent is set to 1 minute to 60 minutes, the reaction temperature is set to 55°C to 100°C, and the amount of coupling agent added is adjusted to a molar ratio of 0.025 to 0.30 relative to the total moles of the polymerization initiator. When the coupling agent is a compound other than an alkoxysilane compound, the following method can be used: the time from when the reaction temperature reaches the maximum temperature to when the coupling agent is added is set to 1 minute to 30 minutes, the reaction time of the coupling agent is set to 1 minute to 35 minutes, the reaction temperature is set to 50°C to 95°C, and the amount of the coupling agent added is adjusted to a molar ratio of 0.025 to 0.20 relative to the total moles of the polymerization initiator.

[0168] (Hydrogenation reaction step)

[0169] The block copolymer of the present embodiment may be subjected to a hydrogenation reaction step for hydrogenating part or all of the unsaturated double bonds derived from the conjugated diene compound after the polymerization step and the coupling step.

[0170] The hydrogenation method is not particularly limited, and can be carried out by a known technique using a hydrogenation catalyst.

[0171] There are no particular limitations on the hydrogenation catalyst, and known catalysts can be used, for example: supported heterogeneous hydrogenation catalysts in which metals such as Ni, Pt, Pd, and Ru are supported on carbon, silicon oxide, aluminum oxide, diatomaceous earth, and the like; so-called Ziegler-type hydrogenation catalysts using organic acid salts of Ni, Co, Fe, Cr, or transition metal salts such as acetylacetonate and reducing agents such as organic aluminum; homogeneous hydrogenation catalysts such as so-called organometallic complexes such as organometallic compounds of Ti, Ru, Rh, and Zr.

[0172] Specifically, the hydrogenation catalysts described in JP-B-42-8704, JP-B-43-6636, JP-B-63-4841, JP-B-1-37970, JP-B-1-53851, and JP-B-2-9041 can be used.

[0173] Among them, preferred hydrogenation catalysts include cyclopentadienyl titanium compounds, reducing organometallic compounds, or mixtures thereof.

[0174] The cyclopentadienyl titanium compound is not particularly limited, and examples thereof include compounds described in Japanese Patent Application Laid-Open No. 8-109219. Specifically, examples thereof include compounds having at least one ligand having a (substituted) cyclopentadienyl skeleton, an indenyl skeleton, or a fluorenyl skeleton, such as biscyclopentadienyl titanium dichloride and mono(pentamethylcyclopentadienyl)titanium trichloride.

[0175] The reducing organometallic compound is not particularly limited, and examples thereof include organoalkali metal compounds such as organolithium, organomagnesium compounds, organoaluminum compounds, organoboron compounds, and organozinc compounds.

[0176] The hydrogenation reaction temperature is preferably 0 to 200°C, more preferably 30 to 150°C. The hydrogen pressure used in the hydrogenation reaction is preferably 0.1 to 15 MPa, more preferably 0.2 to 10 MPa, and even more preferably 0.3 to 5 MPa. The hydrogenation reaction time is preferably 3 minutes to 10 hours, more preferably 10 minutes to 5 hours.

[0177] The hydrogenation reaction can be a batch process, a continuous process, or a combination thereof.

[0178] The block copolymer can be obtained by removing catalyst residues from the solution of the block copolymer obtained by the hydrogenation reaction, and isolating the solution as needed. The solvent separation method is not particularly limited, and examples thereof include: adding a polar solvent such as acetone or alcohol, which is a poor solvent for the hydrogenated block copolymer, to the hydrogenated reaction solution to precipitate the polymer and recover it; adding the hydrogenated reaction solution to hot water with stirring and removing the solvent by steam stripping; and heating the hydrogenated reaction solution to distill off the solvent.

[0179] (Block ratio of block copolymer)

[0180] Furthermore, the amount (mass %) of the polymer block (A) relative to the total amount (100 mass %) of the vinyl aromatic monomer units used to polymerize the block copolymer, i.e., the block ratio, is preferably 90 mass % or more, more preferably 95 mass % or more, and even more preferably 97 mass % or more. By setting the block ratio within the above range, a block copolymer having excellent finish tends to be obtained.

[0181] The amount of the polymer block (A) is obtained by dissolving the block copolymer before hydrogenation in chloroform, adding an osmic acid / tert-butyl hydroperoxide solution to cleave the double bonds of the butadiene component, then adding methanol and filtering. The filtrate is dissolved in chloroform, and the resulting solution is measured for block styrene content by peak intensity (absorption wavelength: 262 nm) using an ultraviolet spectrophotometer.

[0182] (Other processes)

[0183] In the method for producing the block copolymer of the present embodiment, a step of deashing metals derived from a polymerization initiator or the like may be performed as needed.

[0184] In the method for producing the block copolymer of the present embodiment, a step of adding an antioxidant, a neutralizing agent, a surfactant, etc. may be further performed as needed.

[0185] The antioxidant is not particularly limited, and examples thereof include hindered phenol compounds, phosphorus compounds, and sulfur compounds similar to those described below.

[0186] The neutralizing agent is not particularly limited, and examples thereof include various metal stearates, hydrotalcite, and benzoic acid. From the viewpoint of transparency, benzoic acid is preferred.

[0187] There is no particular limitation on the surfactant, and examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants, and the like. There is no particular limitation on the anionic surfactant, and examples thereof include fatty acid salts, alkyl sulfate ester salts, alkyl aryl sulfonates, and the like. In addition, there is no particular limitation on the nonionic surfactant, and examples thereof include polyoxyethylene alkyl ethers, polyoxyethylene alkyl aryl ethers, and the like. In addition, there is no particular limitation on the cationic surfactant, and examples thereof include alkylamine salts, quaternary ammonium salts, and the like. From the perspective of transparency and dielectric properties, it is further preferred that the surfactant does not substantially contain Ca, Li, or Ti atoms. This "substantially does not contain" means that a surfactant containing Ca, Li, or Ti atoms as the main raw material is not actively added, and the use of a surfactant containing Ca, Li, or Ti atoms as impurities is not excluded.

[0188] The block copolymer of this embodiment, which can be manufactured as described above, may include a modified block copolymer in which a functional group containing a polar group selected from nitrogen, oxygen, silicon, phosphorus, sulfur, and tin atoms is bonded to the block copolymer; or a modified block copolymer in which the block copolymer components are modified with a modifier such as maleic anhydride. Such modified block copolymers are obtained by performing a known modification reaction.

[0189] The method for imparting the polar group-containing functional group to the block copolymer is not particularly limited, and examples thereof include a method of adding the polar group-containing functional group to the block copolymer using a compound containing a functional group as a polymerization initiator, monomer, coupling agent, or polymerization terminator.

[0190] As the polymerization initiator containing a functional group, an N-group-containing polymerization initiator is preferred, and examples thereof include, but are not limited to, lithium dioctylamide, lithium di-2-ethylhexylamide, lithium ethylbenzylamide, (3-(dibutylamino)-propyl)lithium, and piperidyllithium.

[0191] In addition, as monomers containing functional groups, compounds containing hydroxyl groups, acid anhydride groups, epoxy groups, amino groups, amide groups, silanol groups, and alkoxysilyl groups in the monomers used in the above polymerization can be cited. Among them, monomers containing N groups are preferred, and examples thereof include, but are not limited to, N,N-dimethylvinylbenzylamine, N,N-diethylvinylbenzylamine, N,N-dipropylvinylbenzylamine, N,N-dibutylvinylbenzylamine, N,N-diphenylvinylbenzylamine, 2-dimethylaminoethylstyrene, 2-diethylaminoethylstyrene, 2-bis(trimethylsilyl)aminoethylstyrene, 1-(4-N,N-dimethylaminophenyl)-1-phenylethylene, N ,N-dimethyl-2-(4-vinylbenzyloxy)ethylamine, 4-(2-pyrrolidinoethyl)styrene, 4-(2-piperidinoethyl)styrene, 4-(2-hexamethyleneiminoethyl)styrene, 4-(2-morpholinoethyl)styrene, 4-(2-thiazinoethyl)styrene, 4-(2-N-methylpiperazinylethyl)styrene, 1-((4-vinylphenoxy)methyl)pyrrolidine, 1-(4-vinylbenzyloxymethyl)pyrrolidine, etc.

[0192] Examples of coupling agents and polymerization terminators containing functional groups include compounds containing hydroxyl groups, acid anhydride groups, epoxy groups, amino groups, amide groups, silanol groups, and alkoxysilyl groups among the above-mentioned coupling agents. Among them, coupling agents containing oxygen atoms are preferred, and examples thereof include, but are not limited to, tetraglycidyl-m-phenylenediamine, tetraglycidyl-1,3-bisaminomethylcyclohexane, tetraglycidyl-p-phenylenediamine, tetraglycidyldiaminodiphenylmethane, diglycidylaniline, γ-caprolactone, γ-glycidoxyethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriphenoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropyldiethylethoxysilane, 1,3-dimethyl-2-imidazolidinone, 1,3-diethyl-2-imidazolidinone, N,N'-dimethylpropyleneurea, and N-methylpyrrolidone.

[0193] (Separation process)

[0194] After the block copolymer of the present embodiment is produced as described above, the block copolymer is isolated, that is, finished, by the method described later.

[0195] When the block copolymer polymerization process is carried out in an inert hydrocarbon solvent, the inert hydrocarbon solvent is removed to separate the block copolymer. Specific methods for removing the solvent include, for example, a method in which the block copolymer is filtered out after separating the solvent by steam stripping, and then dehydrated and dried to obtain the block copolymer; a method in which the block copolymer is concentrated in a flash tank and then devolatilized using a venting extruder; and a method in which the block copolymer is directly devolatilized using a rotary dryer. During steam stripping, a surfactant is preferably used as a granulating agent. Such surfactants are not particularly limited, and examples include the same anionic surfactants, cationic surfactants, and nonionic surfactants as those described above. These surfactants can generally be added at 0.1 ppm to 3000 ppm relative to the water in the stripping zone. From the perspective of transparency and dielectric properties, it is further preferred that the surfactant does not substantially contain Ca, Li, or Ti atoms. The term "substantially free" means that a surfactant containing Ca, Li, or Ti atoms as the main raw material is not actively added, but does not exclude the use of surfactants containing Ca, Li, or Ti atoms as impurities.

[0196] The concentration of the block copolymer in the form of crumbs dispersed in water obtained through the block copolymer polymerization step and the above-mentioned stripping is generally 0.1% to 20% by mass (relative to the water content in the stripping zone). Within this range, no operational problems occur, and crumbs with a good particle size can be obtained. Preferably, the block copolymer crumbs are dehydrated to adjust the moisture content to 1% to 30% by mass, and then dried until the moisture content is 1% or less.

[0197] In the above-mentioned dehydration step of the crumbs, dehydration can be performed by compressed water pressing using a roller, a Banbury dehydrator, a screw extruder type press dehydrator, or the like, or dehydration and drying can be performed simultaneously using a conveyor belt or a box-type hot air dryer.

[0198] [Adhesive composition]

[0199] The adhesive composition of the present embodiment contains the block copolymer of the present embodiment described above and a tackifier.

[0200] The functions required of adhesive compositions vary depending on the intended use, and the required adhesive force and dielectric constant also vary. However, these can be appropriately set by adjusting the structure of the block copolymer and the blending ratio with the tackifier.

[0201] The content of the tackifier in the adhesive composition of the present embodiment is 1 to 250 parts by mass, preferably 5 to 220 parts by mass, and more preferably 10 to 200 parts by mass, per 100 parts by mass of the block copolymer.

[0202] The adhesive composition of this embodiment may further contain a softener.

[0203] The content of the softener is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 80 parts by mass or less, relative to 100 parts by mass of the block copolymer of this embodiment. Thus, an adhesive composition having excellent adhesive strength is obtained.

[0204] The adhesive composition of the present embodiment may contain other components described below as necessary.

[0205] It should be noted that, in the adhesive composition of the present embodiment, other polymers such as styrene-butadiene block copolymers, styrene-isoprene block copolymers, hydrogenated styrene-butadiene block copolymers, and hydrogenated styrene-isoprene block copolymers other than the block copolymer of the present embodiment may be added. In this case, the adhesive composition preferably includes 1 to 250 parts by mass of a tackifier and 0 to 120 parts by mass of a softener relative to 100 parts by mass of the total content of the other polymers and the block copolymer of the present embodiment.

[0206] The adhesive composition of the present embodiment preferably has an adhesive force within a practical range, a relative dielectric constant of 2.5 or less, and a dielectric loss tangent of 0.0007 or less.

[0207] In order to make the relative dielectric constant and dielectric loss tangent satisfy the above range, the total content of Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, and Ni atoms in the adhesive composition is preferably 400 mass ppm or less, more preferably 360 mass ppm or less, and further preferably 340 mass ppm or less. In addition, the content of Ca atoms in the adhesive composition of this embodiment is preferably 300 mass ppm or less, more preferably 200 mass ppm or less, further preferably 100 mass ppm or less, and further preferably 50 mass ppm or less, and further preferably 30 mass ppm or less. In addition, the total content of Li atoms and Ti atoms in the adhesive composition of this embodiment is preferably 300 mass ppm or less, more preferably 250 mass ppm or less, further preferably 130 mass ppm or less, and further preferably 50 mass ppm or less.

[0208] [Optical Adhesive Composition]

[0209] The optical adhesive composition of the present embodiment contains the block copolymer of the present embodiment and a tackifier.

[0210] An "optical adhesive composition" is an adhesive used for bonding optical materials, and is used for bonding polarizing plates or liquid crystal layers in liquid crystal displays, various functional films in touch panel displays, transparent conductive films, and the like.

[0211] The functions required of adhesives for optical materials vary depending on the application, and the required adhesion and dielectric constant also vary. However, these can be appropriately set by adjusting the structure of the block copolymer and the mixing ratio between the block copolymer and the tackifier. In general, in addition to a certain degree of adhesion and dielectric properties, transparency is often required.

[0212] The content of the tackifier in the optical adhesive composition of the present embodiment is 1 to 250 parts by mass, preferably 5 to 220 parts by mass, and more preferably 10 to 200 parts by mass, based on 100 parts by mass of the block copolymer.

[0213] The optical adhesive composition of this embodiment may further contain a softener.

[0214] The content of the softener is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, and even more preferably 80 parts by mass or less, relative to 100 parts by mass of the block copolymer of this embodiment. Thus, an optical adhesive composition having excellent adhesive strength is obtained.

[0215] The optical adhesive composition of the present embodiment may contain other components described below as necessary.

[0216] It should be noted that the optical adhesive composition of this embodiment may contain other polymers other than the block copolymer of this embodiment, such as a styrene-butadiene block copolymer, a styrene-isoprene block copolymer, a hydrogenated styrene-butadiene block copolymer, or a hydrogenated styrene-isoprene block copolymer. In this case, the composition preferably contains 1 to 250 parts by mass of a tackifier and 0 to 120 parts by mass of a softener, relative to 100 parts by mass of the total content of the other polymer and the block copolymer of this embodiment.

[0217] The optical adhesive composition of this embodiment preferably has no color, adhesive strength within a practical range, a total light transmittance of 91% or more, a haze value of 2% or less, a relative dielectric constant of 2.5 or less, and a dielectric loss tangent of 0.0007 or less.

[0218] In order to make the total light transmittance and haze value indicating transparency satisfy the above range, the total content of Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, and Ni atoms in the optical adhesive composition is preferably 400 mass ppm or less, more preferably 360 mass ppm or less, and further preferably 340 mass ppm or less. In addition, the content of Ca atoms in the optical adhesive composition of this embodiment is preferably 300 mass ppm or less, more preferably 200 mass ppm or less, further preferably 100 mass ppm or less, and further preferably 50 mass ppm or less. In addition, the total content of Li atoms and Ti atoms in the optical adhesive composition of this embodiment is preferably 300 mass ppm or less, more preferably 250 mass ppm or less, further preferably 130 mass ppm or less, and further preferably 50 mass ppm or less.

[0219] (Tackifier)

[0220] The adhesive composition and the optical adhesive composition of the present embodiment contain 100 parts by mass of the block copolymer of the present embodiment and 1 to 250 parts by mass of a tackifier.

[0221] The tackifier can be selected in various ways depending on the application and required performance of the adhesive composition and the optical adhesive composition.

[0222] Examples of the tackifier include, but are not limited to, rosin-based compounds such as hydrogenated rosin and pentaerythritol esters of hydrogenated rosin; terpene-based compounds such as hydrogenated derivatives of aromatic modified terpene resins, terpene phenol resins, hydrogenated derivatives of terpene phenol resins, terpene resins (monoterpenes, diterpenes, triterpenes, polyterpenes, etc.), hydrogenated terpene resins, and hydrogenated derivatives of hydrogenated terpene resins; petroleum hydrocarbon-based compounds such as aliphatic petroleum hydrocarbon resins (C5-based resins), hydrogenated derivatives of aliphatic petroleum hydrocarbon resins, aromatic petroleum hydrocarbon resins (C9-based resins), hydrogenated derivatives of aromatic petroleum hydrocarbon resins, dicyclopentadiene-based resins, hydrogenated derivatives of dicyclopentadiene-based resins, C5 / C9 copolymer-based resins, hydrogenated derivatives of C5 / C9 copolymer-based resins, cyclic aliphatic petroleum hydrocarbon resins, hydrogenated derivatives of cyclic aliphatic petroleum hydrocarbon resins, and aromatic group-containing resins.

[0223] The tackifier may be used alone or in combination of two or more.

[0224] It should be noted that the C5 / C9 copolymer resin refers to a copolymerized petroleum resin obtained by polymerizing a mixture of a C5 fraction and a C9 fraction as a raw material.

[0225] The tackifier preferably has a colorless to light yellow hue.

[0226] As the tackifier, a liquid type tackifier having a colorless to light yellow hue, substantially no odor, and good thermal stability may be used.

[0227] From the viewpoint of suppressing coloration and reducing odor, the tackifier is preferably a hydrogenated derivative.

[0228] Examples of hydrogenated derivatives include, but are not limited to, hydrogenated derivatives of aromatic modified terpene resins, hydrogenated derivatives of terpene-phenol resins, hydrogenated derivatives of hydrogenated terpene resins, hydrogenated derivatives of aliphatic petroleum hydrocarbon resins (C5 resins), hydrogenated derivatives of aromatic petroleum hydrocarbon resins (C9 resins), hydrogenated derivatives of dicyclopentadiene resins, hydrogenated derivatives of C5 / C9 copolymer resins, and hydrogenated derivatives of cyclic aliphatic petroleum hydrocarbon resins. Among these, hydrogenated derivatives of aromatic petroleum hydrocarbon resins (C9 resins), hydrogenated derivatives of dicyclopentadiene resins, and hydrogenated derivatives of hydrogenated terpene resins are particularly preferred.

[0229] Commercially available products of tackifiers used in the adhesive composition and optical adhesive composition of this embodiment include, but are not limited to, ALCON P and M series (trade names) manufactured by Arakawa Chemical Co., Ltd., I-Marv S and P series manufactured by Idemitsu Kosan Co., Ltd., Escorez 5000 series (trade name) manufactured by ExxonMobil Chemical Company, CLEARON P series manufactured by YASUHARA CHEMICAL, and FTR / FMR series manufactured by Mitsui Chemicals, Inc.

[0230] When the block copolymer in the optical adhesive composition of the present embodiment has a hydrogenation rate of 90% or higher of double bonds based on conjugated diene monomer units, the tackifier is preferably a hydrogenated derivative from the viewpoint of compatibility.

[0231] Examples of hydrogenated derivatives include hydrogenated derivatives of aromatic modified terpene resins, hydrogenated derivatives of terpene-phenol resins, hydrogenated derivatives of hydrogenated terpene resins, hydrogenated derivatives of aliphatic petroleum hydrocarbon resins (C5 resins), hydrogenated derivatives of aromatic petroleum hydrocarbon resins (C9 resins), hydrogenated derivatives of dicyclopentadiene resins, hydrogenated derivatives of C5 / C9 copolymer resins, and hydrogenated derivatives of cyclic aliphatic petroleum hydrocarbon resins.

[0232] Among these, hydrogenated derivatives of aromatic petroleum hydrocarbon resins (C9 resins), hydrogenated derivatives of dicyclopentadiene resins, hydrogenated derivatives of hydrogenated terpene resins, etc. are particularly preferred. The use of a tackifier having high compatibility tends to increase the adhesive strength.

[0233] Furthermore, the hydrogenated derivatives described above are also preferred from the viewpoints of color tone and dielectric properties.

[0234] In the adhesive composition and optical adhesive composition of this embodiment, the content of the tackifier is 1 to 250 parts by mass relative to 100 parts by mass of the block copolymer, and can be variously selected within this range depending on the application and required performance.

[0235] (Softener)

[0236] The adhesive composition and the optical adhesive composition of the present embodiment preferably further contain a softener.

[0237] The “softener” has a function of reducing the hardness and viscosity of the adhesive composition and the optical adhesive composition of the present embodiment.

[0238] The softener is not particularly limited, and examples thereof include oils; plasticizers; synthetic liquid oligomers; and mixtures thereof.

[0239] Hereinafter, preferred softeners will be described in more detail.

[0240] From the perspective of reducing the viscosity of the adhesive composition and optical adhesive composition of this embodiment, improving adhesion, and reducing hardness, it is preferred to use oils as softeners. The oils are not particularly limited, and examples thereof include well-known paraffinic process oils, cycloparaffinic process oils, aromatic process oils, and mixtures thereof.

[0241] Examples of plasticizers include, but are not limited to, liquid paraffin; fatty acid esters formed from higher fatty acids having 12 to 16 carbon atoms and lower monohydric alcohols having 1 to 4 carbon atoms, such as isopropyl myristate, ethyl laurate, and isopropyl palmitate; fatty acids having 8 to 10 carbon atoms; glycols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, and polypropylene glycol; oils and fats such as olive oil, castor oil, squalene, and lanolin; organic solvents such as ethyl acetate, ethanol, dimethyldecyl sulfoxide, decyl methyl sulfoxide, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, dimethyllaurylamide, dodecyl pyrrolidone, isosorbide, oleyl alcohol, and lauric acid; liquid surfactants; ethoxylated stearyl alcohol, glyceride, isotridecyl myristate, N-methylpyrrolidone, ethyl oleate, oleic acid, diisopropyl adipate, octyl hexadecanoate, 1,3-propylene glycol, and glycerin.

[0242] Among them, compounds that are liquid at room temperature are used.

[0243] The plasticizer may be used alone or in combination of two or more.

[0244] Among plasticizers, glycerides are preferred, and medium-chain fatty acid triglycerides, which are esters of fatty acids having 8 to 10 carbon atoms and glycerol, are more preferred. Examples of medium-chain fatty acid triglycerides include tri(caprylic acid / capric acid) glyceryl.

[0245] In the case where it is desired to make the adhesive composition of the present embodiment and the adhesive composition for optics more flexible, from the aspect of improving exudation, a synthetic liquid oligomer is preferably used as a softening agent. There is no particular limitation on the synthetic liquid oligomer, and examples thereof include styrene oligomers, butadiene oligomers, isoprene oligomers, and butylene oligomers.

[0246] Commercially available products of the softener used in the adhesive composition and optical adhesive composition of this embodiment include, but are not limited to, Diana Fresia S32 (trade name), Dianaprocess oil PW-90 (trade name), Process Oil NS100 (trade name), Process Oil NS90S (trade name) manufactured by Idemitsu Kosan Co., Ltd., White Oil Broom 350 (trade name), DN Oil KP-68 (trade name) manufactured by Kukdong Oil & Chem Co., Ltd., Enerper M1930 (trade name) manufactured by BP Chemicals Co., Ltd., Kaydol (trade name) manufactured by Crompton Co., Ltd., Primol 352 (trade name) manufactured by Esso Co., Ltd., KN4010 (trade name) manufactured by Petro China Company, LV series and HV series manufactured by Nisseki Polybutene Co., Ltd., etc.

[0247] Furthermore, when using a block copolymer having a hydrogenation rate of 90% or higher of double bonds based on conjugated diene monomer units as a component of the adhesive composition and optical adhesive composition of this embodiment, it is preferred to use a paraffinic process oil, a cycloparaffinic process oil, a butadiene oligomer, an isoprene oligomer, a butene oligomer, or the like as a plasticizer for compatibility. Using a highly compatible plasticizer tends to increase adhesive strength and also tends to suppress bleed-out.

[0248] Furthermore, from the viewpoint of color tone, it is preferred to use a softener having a color of 0.5 or less as measured in accordance with ASTM D1500.

[0249] (Other ingredients)

[0250] The adhesive composition and optical adhesive composition of the present embodiment may contain other components such as an antioxidant, a polymer other than the block copolymer of the present embodiment, wax, a stabilizer such as a light stabilizer, and other additives as necessary.

[0251] <Antioxidants>

[0252] Examples of the antioxidant include, but are not limited to, 2,6-di-tert-butyl-4-methylphenol, n-octadecyl-3-(4'-hydroxy-3',5'-di-tert-butylphenyl) propionate, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 2,4-bis[(octylthio)methyl]-6-methylphenol, 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenol, Hindered phenol antioxidants such as propylene glycol acrylate, 2,4-di-tert-amyl-6-[1-(3,5-di-tert-amyl-2-hydroxyphenyl)ethyl]phenyl acrylate, and 2-[1-(2-hydroxy-3,5-di-tert-amylphenyl)]acrylate; sulfur antioxidants such as dilauryl thiodipropionate, lauryl stearyl thiodipropionate, and pentaerythritol tetra(β-laurylthiopropionate); phosphorus antioxidants such as tris(nonylphenyl) phosphite and tris(2,4-di-tert-butylphenyl) phosphite, etc.

[0253] Examples of commercially available antioxidants include Sumilizer GM (trade name), Sumilizer TPD (trade name), and Sumilizer TPS (trade name) manufactured by Sumitomo Chemical Co., Ltd., IRGANOX 1010 (trade name), IRGANOX HP2225FF (trade name), Irgafos 168 (trade name), and IRGANOX 1520 (trade name) manufactured by Ciba Specialty Chemicals, and JF77 (trade name) manufactured by Johoku Chemical Co., Ltd.

[0254] These antioxidants may be used alone or in combination of two or more.

[0255] The content of the antioxidant in the adhesive composition and the optical adhesive composition of the present embodiment is arbitrary, but is preferably 5% by mass or less relative to 100% by mass of the adhesive composition and the optical adhesive composition.

[0256] <Polymers Other Than Block Copolymers of the Present Embodiment>

[0257] The polymer other than the block copolymer of the present embodiment is not particularly limited, and examples thereof include polyolefin-based copolymers, vinyl aromatic copolymers, and other rubbers.

[0258] The polyolefin-based copolymer is not particularly limited, and examples thereof include atactic polypropylene, ethylene-ethyl acrylate copolymer, and α-olefin-based polymers.

[0259] The vinyl aromatic copolymer is not particularly limited, and examples thereof include polymers other than component (a) and component (b), such as styrene-ethylene block copolymers, styrene-butadiene block copolymers, styrene-propylene block copolymers, styrene-isoprene block copolymers, styrene-butadiene-isoprene block copolymers, styrene-butadiene / isoprene block copolymers, hydrogenated styrene-butadiene block copolymers, hydrogenated styrene-isoprene block copolymers, hydrogenated styrene-butadiene-isoprene block copolymers, and hydrogenated styrene-butadiene / isoprene block copolymers. The vinyl aromatic copolymer may be a vinyl aromatic thermoplastic resin or a vinyl aromatic elastomer.

[0260] The other rubbers are not particularly limited, and examples thereof include natural rubber; synthetic rubbers such as isoprene-isobutylene rubber, polyisoprene rubber, butadiene rubber, styrene-butadiene rubber, styrene-isoprene rubber, propylene-butene rubber, ethylene-propylene rubber, chloroprene rubber, acrylic rubber, isoprene-isobutylene rubber, and polypentene rubber.

[0261] <Wax>

[0262] The adhesive composition and the optical adhesive composition of the present embodiment may contain wax as needed.

[0263] The wax is not particularly limited, and for example, paraffin wax, microcrystalline wax, low-molecular-weight polyethylene wax, etc. may be added.

[0264] The wax content in the adhesive composition and optical adhesive composition of this embodiment is preferably 2% to 10% by mass, more preferably 5% to 10% by mass. Furthermore, the melting point of the wax is preferably 50°C to 110°C, more preferably 65°C to 110°C, further preferably 70°C to 110°C, and even more preferably 75°C to 110°C. Furthermore, the softening point of the tackifier used in this case is preferably 70°C or higher, more preferably 80°C or higher.

[0265] <Light Stabilizer>

[0266] The adhesive composition and the optical adhesive composition of the present embodiment may contain a light stabilizer as needed.

[0267] The light stabilizer is not particularly limited, and examples thereof include benzotriazole-based UV absorbers such as 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-(2'-hydroxy-3',5'-tert-butylphenyl)benzotriazole, and 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)-5-chlorobenzotriazole; benzophenone-based UV absorbers such as 2-hydroxy-4-methoxybenzophenone; and hindered amine-based light stabilizers.

[0268] [Properties of Adhesive Composition and Optical Adhesive Composition]

[0269] The adhesive composition and the optical adhesive composition of the present embodiment have practically sufficient transparency and sufficiently lower dielectric properties than those of acrylic adhesives.

[0270] The properties of the optical adhesive composition according to the present embodiment can be measured under the measurement conditions described in the examples below.

[0271] [Adhesive composition and method for producing an optical adhesive composition]

[0272] The adhesive composition and the optical adhesive composition of the present embodiment can be produced by mixing the block copolymer of the present embodiment, a tackifier, and, if necessary, a softener, other polymers, and other additives.

[0273] The mixing method is not particularly limited, and examples thereof include a method of stirring the block copolymer, tackifier, softener, other polymers, and additives in a solvent. The solvent is preferably toluene or a mixed solvent of toluene and ethyl acetate.

[0274] [Adhesive composition and method for applying the optical adhesive composition]

[0275] The adhesive composition and the optical adhesive composition of the present embodiment can be applied onto a specific substrate to obtain a product having a specific adhesive layer, such as an adhesive tape.

[0276] The method for applying the adhesive composition and the optical adhesive composition is not particularly limited as long as the target product can be obtained. Examples include a method of dissolving the adhesive composition or the optical adhesive composition in a solvent and applying the solution.

[0277] [Adhesive Sheets, Optical Adhesive Sheets]

[0278] The adhesive sheet of this embodiment has an adhesive layer composed of the optical adhesive composition of this embodiment.

[0279] The adhesive sheet of the present embodiment is obtained by applying the optical adhesive composition of the present embodiment onto a specific substrate.

[0280] The adhesive sheet of this embodiment has sufficient transparency for practical use, small relative dielectric constant and dielectric loss tangent values, and can achieve excellent low dielectric constant. Therefore, it can be used as an optical adhesive sheet for forming a device adhesive layer for bonding the constituent layers of electronic devices having a display module.

[0281] Figure 2 Schematic cross-sectional view of an example of an electronic device including a display module using the optical adhesive sheet of this embodiment is shown in FIG.

[0282] An electronic device having a display module is an article that operates by controlling the flow of electrons, and examples thereof include devices having a liquid crystal display, an organic EL display, an LED display, etc. In addition, these displays may be touch panel displays.

[0283] These displays generally have multiple constituent layers, are equipped with the adhesive layer for bonding each layer.Due to being a display, when transparency is needed, it is preferred that the optical adhesive composition with excellent transparency of the present embodiment is used to form the adhesive layer (hereinafter sometimes referred to as device adhesive layer) of an electronic device. In addition, in the case where the transmission loss caused by the device adhesive layer for bonding the layer (electronic module) through which electrons such as an electronic circuit or a conductive film flow and the glass cover etc. are bonded is suppressed to be relatively low, it is preferred that the adhesive composition with excellent dielectricity of the present embodiment is used to form the purposes of the device adhesive layer of an electronic device.

[0284] exist Figure 2 In the illustrated electronic device 10 , a specific display module 3 and a cover glass 2 are bonded together via a device adhesive layer 1 formed of the optical adhesive sheet of this embodiment.

[0285] in addition, Figure 3 Schematic cross-sectional view of another example of an electronic device including a display module using the optical adhesive sheet of this embodiment is shown in FIG. Figure 3 In the embodiment, a specific functional layer 4 is stacked on a display module 3 .

[0286] The functional layer 4 may be, for example, a conductive layer, specifically, a transparent conductive layer formed of a translucent film such as ITO (indium tin oxide) having a desired pattern on a translucent base layer such as a polyethylene terephthalate film.

[0287] The optical adhesive sheet of the present embodiment can be used as an adhesive layer (device adhesive layer) constituting electronic devices having various structures.

[0288] Figures 4 to 6 A schematic cross-sectional view of another example of an electronic device is shown in FIG.

[0289] exist Figure 4 、 Figure 5 The device adhesive layer 1 formed of the optical adhesive sheet of this embodiment is provided between the transparent electrode 6 and other transparent electrodes 6 provided in the display module 3 .

[0290] It should be noted that if Figures 4 and 5 As shown, a configuration may be adopted in which a sensor layer 5 constituting a touch sensor is further provided on the display surface side of the display module 3 via the device adhesive layer 1 formed of the optical adhesive sheet of this embodiment.

[0291] More specifically, if Figure 6 As shown, the following structure is shown: the display module 3 has a liquid crystal panel 8, a polarizer 7, a light guide plate 9 and a light source 11, and on the display surface side of the above-mentioned display module 3, a polarizer 7 and a sensor layer 5 constituting a touch sensor are provided through a device adhesive layer 1 formed by the optical adhesive sheet of this embodiment; in addition, it can be the following structure: the above-mentioned sensor layer 5 and the glass cover 2 are stacked through other device adhesive layers 1, the above-mentioned device adhesive layer 1 is adjacent to the above-mentioned polarizer 7, and the above-mentioned other device adhesive layer 1 is adjacent to the above-mentioned sensor layer 5.

[0292] Example

[0293] Hereinafter, the present invention will be described in detail with reference to specific Examples and Comparative Examples. However, the present invention is not limited to the following Examples and Comparative Examples.

[0294] In addition, in Examples and Comparative Examples, the measurement of physical properties and evaluation of characteristics of polymers were performed by the following methods.

[0295] [(1): Physical properties of block copolymer]

[0296] <(1-1) Content of Vinyl Aromatic Monomer Unit (Styrene)>

[0297] A certain amount of the block copolymer was dissolved in chloroform and measured using an ultraviolet spectrophotometer (UV-2450 manufactured by Shimadzu Corporation). The content of the vinyl aromatic monomer unit (styrene) was calculated from the peak intensity at the absorption wavelength (262 nm) attributed to the vinyl aromatic compound component (styrene) using a calibration curve.

[0298] <(1-2) Weight Average Molecular Weight>

[0299] The weight average molecular weights of components (I) and (II) were determined based on the molecular weights of the peaks in the chromatogram using a calibration curve obtained by measuring commercially available standard polystyrene (created using the peak molecular weight of the standard polystyrene) under the measurement conditions described below.

[0300] For hydrogenated products, the weight average molecular weight of the block copolymer after hydrogenation was measured.

[0301] First, a single peak having the lowest peak molecular weight in the molecular weight range of 20,000 or more and having an area ratio of 0.1 or more relative to the total peak area of ​​the block copolymer calculated by peak segmentation described later is defined as component (I), and all peaks in a higher molecular weight range are defined as component (II).

[0302] The weight average molecular weights of the components (I) and (II) were determined by vertically dividing the GPC curve from the inflection points between the peaks to the baseline using the system / software described later.

[0303] Here, the inflection point between the peaks of component (I) and component (II) is the lowest point (valley) in the vertical direction between adjacent peaks. Furthermore, if the lowest point continues, it is the midpoint. Using these inflection points, the waveform separation function within the aforementioned system / software is used to perform vertical segmentation, and the weight-average molecular weight and area ratio of each segmentation are calculated.

[0304] (Measurement conditions)

[0305] GPC: ACQUITY APC system (manufactured by Waters Corporation, Japan)

[0306] System (measurement / analysis) software: Empower3

[0307] Detector: RI

[0308] Refractive index unit full scale: 500μRIU

[0309] Output full scale: 2000mV

[0310] Sampling rate: 10 points / sec

[0311] Column: ACQUITY APC XT125 (4.6mm×150mm): 1

[0312] ACQUITY APC XT200 (4.6mm×150mm): 1 piece

[0313] ACQUITY APC XT900 (4.6mm×150mm): 1 piece

[0314] ACQUITY APC XT450 (4.6mm×150mm): 1 piece

[0315] Solvent: THF

[0316] Flow rate: 1.0 mL / min

[0317] Concentration: 0.1 mg / mL

[0318] Column temperature: 40°C

[0319] Injection volume: 20 μL

[0320] <(1-3) Contents of Component (I) and Component (II)>

[0321] The ratio of the area of ​​component (I) to the total peak area in the elution curve measured in (1-2) above was taken as the content of component (I).

[0322] The content of component (II) is determined as the ratio of the area of ​​all peaks having a molecular weight higher than the molecular weight range of component (I) to the total peak area in the elution curve measured in (1-2) above.

[0323] <(1-4) Weight Average Molecular Weight of Components (II-1), (II-2), and (II-3), Area Ratio in GPC Curve, and Content of Each Component>

[0324] In component (II), a peak having a peak top located at 1.5 times or more and less than 2.5 times the weight average molecular weight of component (I) is designated as component (II-1), a peak having a peak top located at 2.5 times or more and less than 3.5 times the weight average molecular weight of component (I) is designated as component (II-2), and a peak having a peak top located at 3.5 times or more and less than 4.5 times the weight average molecular weight of component (I) is designated as component (II-3).

[0325] The area ratios of the areas of component (II-1), component (II-2), and component (II-3) relative to the total area of ​​component (II), as well as the weight-average molecular weight and further the weight-average molecular weight ratio, were determined by performing GPC measurement using the above-described apparatus and conditions, and then performing vertical segmentation of the GPC curve at the inflection points between the peaks up to the baseline using the same system / software as described above.

[0326] Here, the inflection point between each peak of components (II-1), (II-2), and (II-3) is the lowest point (valley) between adjacent peaks in the vertical direction. Furthermore, if the lowest point continues, it is the midpoint between them. Using these inflection points, the waveform separation function within the aforementioned system / software is used to perform vertical segmentation. After segmentation, the weight-average molecular weights, weight-average molecular weight ratios, and area ratios are calculated.

[0327] The ratio of the areas of components (II-1), (II-2), and (II-3) to the total peak area in the GPC curve measured above was taken as the content of components (II-1) to (II-3).

[0328] <(1-5) 10% by mass toluene solution viscosity>

[0329] The viscosity of a 10% by mass toluene solution of the block copolymer was measured using a Cannon-Fenske viscometer in a thermostatic bath controlled at 25°C.

[0330] A 10 mass % toluene solution viscosity of the block copolymer of 240 mPa·s or less was judged to be good, 200 mPa·s or less was judged to be particularly good, and 160 mPa·s or less was evaluated to be extremely good.

[0331] <(1-6) Vinyl Bond Amount of Conjugated Diene Monomer Unit>

[0332] The vinyl bond content of the conjugated diene monomer unit was calculated using the block copolymer before hydrogenation by the Hampton method using an infrared spectrophotometer (FT / IR-230, manufactured by JASCO Corporation).

[0333] <(1-7) Hydrogenation Rate>

[0334] The hydrogenation rate of the double bonds of the conjugated diene monomer units in the block copolymer was measured using a nuclear magnetic resonance apparatus (NMR) under the following conditions.

[0335] First, a large amount of methanol is added to the reaction solution after the hydrogenation reaction to precipitate the block copolymer and recover it. Next, the block copolymer is extracted with acetone and the extract is vacuum dried to obtain the block copolymer. 1 H-NMR measurement of the sample.

[0336] 1 The conditions for H-NMR measurement are as follows.

[0337] (Measurement conditions)

[0338] Measuring equipment: JNM-LA400 (manufactured by JEOL)

[0339] Solvent: deuterated chloroform

[0340] Measurement sample: Extracts of polymer before and after hydrogenation

[0341] Sample concentration: 50 mg / mL

[0342] Observation frequency: 400MHz

[0343] Chemical shift standard: TMS (tetramethylsilane)

[0344] Pulse delay: 2.904 seconds

[0345] Scan times: 64 times

[0346] Pulse width: 45°

[0347] Measurement temperature: 26°C

[0348] <(1-8) Metal content>

[0349] The amount of metal contained in the block copolymer was measured using inductively coupled plasma (ICP, Inductivity Coupled Plasma, manufactured by Shimadzu Corporation, device name: ICPS-7510).

[0350] First, the block copolymer is completely dissolved using sulfuric acid and nitric acid. An aqueous solution containing metal components is then sprayed into an argon plasma. The intensity of the wavelengths of light emitted therefrom, which are unique to each metal element, is measured. The amount of metal contained in 100 parts by mass of the block copolymer (ppm by mass) is determined using a calibration curve method.

[0351] <(1-9) Toluene Solution Haze>

[0352] The haze of a toluene solution of a block copolymer was evaluated by mixing 10 g of the block copolymer and 40 g of toluene in a 50 mL glass screw-cap tube to prepare a toluene solution of the block copolymer. A piece of paper printed with the letter "A" (10 pt) was placed in contact with the screw-cap tube and observed from the side opposite to the side on which the paper was placed. The evaluation criteria are as follows.

[0353] ◎: The printed text does not appear blurry.

[0354] ○: The printed text looks a little blurry.

[0355] △: The printed text looks very blurry.

[0356] ×: I didn’t know there were words.

[0357] <(1-10) Dielectric Properties>

[0358] The dielectric properties of the block copolymer were measured under the following conditions.

[0359] (Measurement conditions)

[0360] Measurement method: Cylindrical cavity resonator method

[0361] Measurement equipment: Vector network analyzer HP8510C (manufactured by Agilent Technologies)

[0362] synthesized sweeper HP83651A (manufactured by Agilent Technologies)

[0363] Test set HP8517B (manufactured by Agilent Technologies)

[0364] Test piece size: 100mm×60mm×0.6mm

[0365] Resonator shape: Cylinder with inner diameter Φ42mm and height 30mm

[0366] Measurement frequency: around 10 GHz

[0367] Pretreatment: C-90h / 22±1℃ / 60±5%RH

[0368] Test environment: 21°C / 56%RH

[0369] Usage mode:TE 011

[0370] A relative dielectric constant of less than 2.35 was evaluated as good, a relative dielectric constant of less than 2.30 was evaluated as particularly good, and a relative dielectric constant of less than 2.25 was evaluated as extremely good.

[0371] A dielectric loss tangent of less than 0.0015 was evaluated as good, a dielectric loss tangent of less than 0.0010 was evaluated as particularly good, and a dielectric loss tangent of less than 0.0070 was evaluated as extremely good.

[0372] [(2): Adhesive properties]

[0373] Adhesive compositions were prepared by dissolving 100 parts by mass of the block copolymers of Examples 1 to 16 and Comparative Examples 1 and 2 in toluene 20 parts by mass of FMR0150 manufactured by Mitsui Chemicals as a tackifier and 20 parts by mass of LV-100 manufactured by Nisseki Polybutene Co., Ltd. as a softener.

[0374] In addition, the adhesive sheet with the adhesive layer thickness of 50 micrometers used for the evaluation method mentioned later was produced by applying each adhesive composition on the surface of a separator and drying it.

[0375] <(2-1) Adhesion>

[0376] The adhesive sheet having a thickness of 50 μm prepared as described above was cut into a strip having a width of 20 mm, and was bonded to a glass substrate by pressing with a 2 kg roller by reciprocating once.

[0377] After 20 minutes, the film was peeled off at a peeling speed of 300 mm / min and a peeling angle of 180°, and the adhesive strength at that time was measured (unit: N / 20 mm).

[0378] Adhesive strength of 14.0 N / 20 mm or more was evaluated as good, and adhesive strength of 16.0 N / 20 mm or more was evaluated as particularly good.

[0379] <(2-2) Heat-resistant foaming properties>

[0380] An adhesive sheet having an adhesive layer thickness of 50 μm was transferred to 100 μm thick PET (polyethylene terephthalate), attached to Mitsubishi Plastics polycarbonate MR-58, and allowed to stand in an environment of 85° C. and 85% RH.

[0381] The appearance of the adhesive sheet was visually evaluated according to the following criteria.

[0382] (evaluate)

[0383] ◎: No abnormality in appearance was found.

[0384] ○: per 1cm 2 No more than one bubble with a diameter of 0.1 mm or less was confirmed.

[0385] △: per 1cm 2 Two to five bubbles with a diameter of 0.1 mm or less were confirmed, or bubbles with a diameter exceeding 0.1 mm and 1.0 mm or less were confirmed.

[0386] ×: per 1cm 2 Six or more bubbles were confirmed, or bubbles with a diameter exceeding 1.0 mm were confirmed.

[0387] [Preparation of block copolymer]

[0388] (Preparation of Hydrogenation Catalyst)

[0389] In the Examples and Comparative Examples described below, the hydrogenation catalyst used in producing the block copolymer was prepared by the following method.

[0390] A reaction container equipped with a stirrer was purged with nitrogen in advance, and 1 L of dried and purified cyclohexane was added thereto.

[0391] Next, 100 mmol of bis(η5-cyclopentadienyl)titanium dichloride was added, and while the mixture was thoroughly stirred, a n-hexane solution containing 200 mmol of trimethylaluminum was added, and the mixture was reacted at room temperature for about 3 days.

[0392] Thus, a hydrogenation catalyst was obtained.

[0393] (Preparation of Block Copolymer)

[0394] <Example 1>

[0395] Batch polymerization was carried out using a jacketed tank reactor with a stirring device and an internal volume of 100 L according to the following method.

[0396] First, 36 L of cyclohexane was charged into a reactor, and after adjusting the temperature to 55° C., 0.116 parts by mass of n-butyl lithium (hereinafter also referred to as “Bu-Li”) and 0.4 mol of N,N,N′,N′-tetramethylethylenediamine (hereinafter also referred to as “TMEDA”) were added to 100 parts by mass of the total amount of butadiene monomer and styrene monomer charged into the reactor (hereinafter referred to as “total monomers”).

[0397] Next, 12.5 parts by mass of styrene was added over 5 minutes, followed by further reaction for 15 minutes (the temperature reached 65° C. due to polymerization reaction). At this time, the polymer solution was sampled and the polymerization conversion of styrene was measured, which was 100%.

[0398] Next, a cyclohexane solution containing 87.5 parts by mass of butadiene (concentration 40 parts by mass) was continuously added to the reactor at a constant rate over 60 minutes. The reaction was then continued for a further 10 minutes. Three minutes after the reaction temperature reached a maximum of 86°C, tetraethoxysilane was added as a coupling agent at a ratio of 0.114 mol per mol of Bu-Li, and the coupling reaction was allowed to proceed for 20 minutes. Subsequently, 0.6 mol of methanol per mol of Bu-Li was added to terminate the polymerization reaction, yielding a block copolymer.

[0399] Next, the hydrogenation catalyst was added to the obtained block copolymer in an amount of 100 ppm as titanium per 100 parts by mass of the block copolymer, and a hydrogenation reaction was carried out under conditions of a hydrogen pressure of 0.9 MPa and a temperature of 90° C. for 45 minutes.

[0400] Thereafter, 0.3 parts by mass of octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate as a stabilizer was added to 100 parts by mass of the block copolymer, and 0.05 parts by mass of styrene-maleic anhydride copolymer sodium salt as a surfactant was added to 100 parts by mass of the block copolymer. The solvent was removed by steam stripping, and the mixture was dried in a dryer to obtain Block Copolymer 1.

[0401] <Example 2>

[0402] The hydrogenation reaction was carried out in the same manner as in Example 1. Subsequently, 0.3 parts by mass of octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate was added as a stabilizer to 100 parts by mass of the block copolymer, and the mixture was directly devolatilized using a drum dryer to obtain Block Copolymer 2.

[0403] <Example 3>

[0404] The hydrogenation catalyst was changed to 200 ppm as titanium per 100 parts by mass of the block copolymer, and direct devolatilization was performed using a drum dryer. Other conditions were the same as in Example 1 to obtain Block Copolymer 3.

[0405] <Example 4>

[0406] The hydrogenation reaction time was changed to 25 minutes, and a direct devolatilization treatment was performed using a drum dryer. Other conditions were the same as in Example 1 to obtain a block copolymer 4.

[0407] <Example 5>

[0408] The dimethyldimethoxysilane used as the coupling agent was changed to 0.225 per 1 mol of Bu-Li, and direct devolatilization was performed using a drum dryer. Other conditions were the same as in Example 1 to obtain a block copolymer 5.

[0409] <Example 6>

[0410] Block Copolymer 6 was obtained by directly devolatilizing using a drum dryer, except that the coupling agent dimethyldimethoxysilane was changed to 0.225 per mol of Bu-Li, and 200 ppm of a hydrogenation catalyst was added as titanium per 100 parts by mass of the block copolymer.

[0411] <Example 7>

[0412] After the butadiene reaction in Example 1, 1.0 mol of methanol was added to 1 mol of Bu-Li without adding a coupling agent to terminate the polymerization reaction. The mixture was transferred to a 200 L tank reactor and subjected to additional polymerization in a 100 L tank reactor.

[0413] First, 36 L of cyclohexane was charged into a reactor, and after adjusting the temperature to 55° C., 0.056 parts by mass of n-butyl lithium (hereinafter also referred to as “Bu-Li”) and 0.4 mol of N,N,N′,N′-tetramethylethylenediamine (hereinafter also referred to as “TMEDA”) were added to 100 parts by mass of the total amount of butadiene monomer and styrene monomer charged into the reactor (hereinafter referred to as “total monomers”).

[0414] Next, 6.0 parts by mass of styrene was added over 5 minutes, followed by further reaction for 15 minutes (the temperature reached 65° C. due to polymerization reaction). At this time, the polymer solution was sampled and the polymerization conversion of styrene was measured, which was 100%.

[0415] Next, a cyclohexane solution containing 87.5 parts by mass of butadiene (concentration: 40 parts by mass) was continuously added to the reactor at a constant rate over 60 minutes, followed by a further 10 minutes of reaction (the polymerization reaction reached 85°C). At this point, the polymer solution was sampled and the polymerization conversion of butadiene was measured, which was 100%.

[0416] Next, 6.5 parts by mass of styrene was added over 5 minutes, followed by a further 15-minute reaction. Three minutes after the reaction temperature reached a maximum temperature of 90°C, 1.0 mol of methanol was added per 1 mol of Bu-Li to terminate the polymerization reaction, and the mixture was transferred to a tank reactor with an internal volume of 200 L.

[0417] Next, 200 ppm of the hydrogenation catalyst as titanium per 100 parts by mass of the block copolymers was added to the two block copolymers in a 200 L reactor, and hydrogenation was carried out under conditions of a hydrogen pressure of 0.9 MPa and a temperature of 90° C. for 45 minutes.

[0418] Thereafter, 0.3 parts by mass of octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate as a stabilizer was added to 100 parts by mass of the block copolymer, and 0.05 parts by mass of styrene-maleic anhydride copolymer sodium salt as a surfactant was added to 100 parts by mass of the block copolymer, and the mixture was directly devolatilized using a drum dryer to obtain block copolymer 7.

[0419] <Example 8>

[0420] As coupling agents, tetraethoxysilane was changed to 0.071 mol per mol of Bu-Li, and methanol was changed to 0.75 mol per mol of Bu-Li, and direct devolatilization was performed using a drum dryer. Other conditions were the same as in Example 1 to obtain block copolymer 8.

[0421] <Example 9>

[0422] As coupling agents, tetraethoxysilane was changed to 0.214 mol per mol of Bu-Li, and methanol was changed to 0.25 mol per mol of Bu-Li, and direct devolatilization was performed using a drum dryer. Other conditions were the same as in Example 1 to obtain block copolymer 9.

[0423] <Example 10>

[0424] Batch polymerization was carried out using a jacketed tank reactor equipped with a stirring device and an internal volume of 100 L by the following method.

[0425] First, 36 L of cyclohexane was charged into a reactor, and after adjusting the temperature to 55° C., 0.061 parts by mass of n-butyl lithium (hereinafter also referred to as “Bu-Li”) and 0.4 mol of N,N,N′,N′-tetramethylethylenediamine (hereinafter also referred to as “TMEDA”) were added to 100 parts by mass of the total amount of butadiene monomer and styrene monomer charged into the reactor (hereinafter referred to as “total monomers”).

[0426] Next, 6.0 parts by mass of styrene was added over 5 minutes, followed by further reaction for 15 minutes (the temperature reached 65° C. due to polymerization reaction). At this time, the polymer solution was sampled and the polymerization conversion of styrene was measured, which was 100%.

[0427] Next, a cyclohexane solution containing 87.5 parts by mass of butadiene (concentration: 40 parts by mass) was continuously added to the reactor at a constant rate over 60 minutes, followed by a further 10 minutes of reaction (the polymerization reaction reached 85°C). At this point, the polymer solution was sampled and the polymerization conversion of butadiene was measured, which was 100%.

[0428] Next, 6.5 parts by mass of styrene was added over 5 minutes, followed by further reaction for 15 minutes. Three minutes after the reaction temperature reached a maximum temperature of 90°C, 1.0 mol of methanol was added per 1 mol of Bu-Li to terminate the polymerization reaction and obtain a block copolymer.

[0429] Next, the hydrogenation catalyst was added to the obtained block copolymer in an amount of 100 ppm as titanium per 100 parts by mass of the block copolymer, and a hydrogenation reaction was carried out under conditions of a hydrogen pressure of 0.9 MPa and a temperature of 90° C. for 45 minutes.

[0430] Thereafter, 0.3 parts by mass of octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate as a stabilizer was added to 100 parts by mass of the block copolymer, and 0.05 parts by mass of styrene-maleic anhydride copolymer sodium salt as a surfactant was added to 100 parts by mass of the block copolymer, and the mixture was directly devolatilized using a drum dryer to obtain block copolymer 10.

[0431] <Example 11>

[0432] Block copolymer 11 was obtained by directly devolatilizing using a drum dryer, except that the addition amount of Bu-Li was changed to 0.100 parts by mass, the addition amount of styrene was changed to 30.0 parts by mass, and the addition amount of butadiene was changed to 70 parts by mass.

[0433] <Example 12>

[0434] Block copolymer 12 was obtained by directly devolatilizing using a drum dryer except that the addition amount of Bu-Li was changed to 0.090 parts by mass, the addition amount of styrene was changed to 43.0 parts by mass, and the addition amount of butadiene was changed to 57 parts by mass.

[0435] <Example 13>

[0436] The amount of Bu-Li added was changed to 0.200 parts by mass, and direct devolatilization was performed using a drum dryer. Other conditions were the same as in Example 1 to obtain a block copolymer 13.

[0437] <Example 14>

[0438] The amount of Bu-Li added was changed to 0.070 parts by mass, and direct devolatilization was performed using a drum dryer. Other conditions were the same as in Example 1 to obtain a block copolymer 14.

[0439] <Example 15>

[0440] The surfactant was changed to a mixture of polyoxyethylene alkyl ether phosphate and calcium hydroxide, and direct devolatilization was performed using a drum dryer. Other conditions were the same as in Example 1 to obtain Block Copolymer 15.

[0441] <Example 16>

[0442] After drying the block copolymer, 30 ppm of calcium stearate was added as calcium per 100 parts by mass of the block copolymer, and the block copolymer was directly devolatilized using a drum dryer.

[0443] <Comparative Example 1>

[0444] The hydrogenation catalyst was changed to 300 ppm as titanium per 100 parts by mass of the block copolymer, and direct devolatilization was performed using a drum dryer. Block copolymer 17 was obtained in the same manner as in Example 1 under other conditions.

[0445] <Comparative Example 2>

[0446] After drying the block copolymer, 300 ppm of calcium stearate was added as calcium per 100 parts by mass of the copolymer, and the mixture was directly devolatilized using a drum dryer.

[0447] Tables 1 to 3 show the physical property values ​​of the block copolymers of Examples 1 to 16 and Comparative Examples 1 and 2.

[0448] In addition, the characteristics of Examples 1 to 16 and Comparative Examples 1 and 2 were evaluated by the above-mentioned methods.

[0449] Furthermore, an adhesive tape was obtained by the above-mentioned method for producing an adhesive tape, and the obtained adhesive tape was evaluated by the above-mentioned method.

[0450] The evaluation results are shown in Tables 1 to 3.

[0451]

[0452]

[0453]

Table 3

[0454]

[0455] The results in Tables 1 to 3 show that Examples 1 to 16 produced solutions with low haze and high transparency, while Comparative Examples 1 and 2 produced solutions with low transparency. Furthermore, a comparison between Examples 2 and 3 shows that lower Li and Ti contents yielded solutions with higher transparency. Furthermore, a comparison between Examples 6 and 7 shows that, at the same metal content, coupling with a coupling agent containing an oxygen atom in the coupling agent residue yielded a solution with higher transparency. Furthermore, a comparison between Examples 2 and 4 shows that a higher hydrogenation rate leads to lower relative permittivity and dielectric loss tangent. Furthermore, a comparison between Example 2 and Examples 11 and 12 shows that a lower content of vinyl aromatic monomer units leads to a lower relative permittivity. Furthermore, a comparison between Example 2 and Examples 15 and 16 shows that a lower Ca content leads to a lower dielectric loss tangent. Furthermore, a comparison between Example 2 and Example 3 shows that a lower Li and Ti content further reduces the dielectric loss tangent.

[0456] Industrial Applicability

[0457] The block copolymer of the present invention has industrial applicability as a material for an adhesive composition.

Claims

1. A block copolymer for an adhesive composition, wherein: The block copolymer comprises a polymer block (A) mainly composed of vinyl aromatic monomer units and a polymer block (B) mainly composed of conjugated diene monomer units. The total content of Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, and Ni atoms is 400 ppm by mass or less.

2. The block copolymer according to claim 1, wherein The content of Ca atoms is 300 mass ppm or less.

3. The block copolymer according to claim 1 or 2, wherein The content of Ca atoms is 50 mass ppm or less.

4. The block copolymer according to claim 1 or 2, wherein The total content of Li atoms and Ti atoms is 300 mass ppm or less.

5. The block copolymer according to claim 1 or 2, wherein The hydrogenation rate of double bonds based on the conjugated diene monomer units in the block copolymer is 70% or more.

6. The block copolymer according to claim 1 or 2, wherein The block copolymer contains: 20% by mass or more and 90% by mass or less of component (I), and 10% by mass or more and 80% by mass or less of component (II), The component (I) is a block copolymer having one polymer block (A) mainly composed of vinyl aromatic monomer units and at least one polymer block (B) mainly composed of conjugated diene monomer units, and having a weight average molecular weight of 30,000 to 200,000. The component (II) is a block copolymer comprising at least one component selected from the group consisting of the following components (II-1), (II-2), and (II-3), Component (II-1): a component having at least two polymer blocks (A) mainly composed of vinyl aromatic monomer units and at least one polymer block (B) mainly composed of conjugated diene monomer units, and having a weight average molecular weight that is 1.5 times or more and less than 2.5 times the weight average molecular weight of component (I); Component (II-2): a component having at least two polymer blocks (A) mainly composed of vinyl aromatic monomer units and at least one polymer block (B) mainly composed of conjugated diene monomer units, and having a weight average molecular weight that is 2.5 times or more and less than 3.5 times the weight average molecular weight of component (I); Component (II-3): A component having at least two polymer blocks (A) mainly composed of vinyl aromatic monomer units and at least one polymer block (B) mainly composed of conjugated diene monomer units, and having a weight average molecular weight that is 3.5 times or more and less than 4.5 times the weight average molecular weight of the above-mentioned component (I).

7. The block copolymer according to claim 1 or 2, wherein The block copolymer comprises a coupled polymer, The coupled polymer comprises a coupling agent residue containing an oxygen atom.

8. The block copolymer according to claim 6, wherein The weight average molecular weight of the component (I) is 82,000 or more and less than 100,000.

9. The block copolymer according to claim 1 or 2, wherein The content of the vinyl aromatic monomer unit is 5.0% by mass or more and 35.0% by mass or less.

10. The block copolymer according to claim 1 or 2, wherein The total content of Li, Mg, Al, Si, P, Ca, Ti, Fe, Co, and Ni atoms is 360 mass ppm or less.

11. The block copolymer according to claim 1 or 2, wherein The conjugated diene monomer units of the block copolymer have a vinyl bond content of 25% or more and 55% or less before hydrogenation.

12. The block copolymer according to claim 1 or 2, wherein The toluene solution viscosity of the block copolymer is greater than or equal to 50 mPa·s.

13. An adhesive composition comprising: 100 parts by mass of the block copolymer according to any one of claims 1 to 12, and 1 to 250 parts by mass of a tackifier. The adhesive composition according to claim 13 , further comprising 120 parts by mass or less of a softener. The adhesive composition according to claim 13 or 14, which is an optical adhesive composition. 16 . An adhesive sheet comprising an adhesive layer comprising the adhesive composition according to claim 13 . 17 . The adhesive sheet according to claim 16 , which is an optical adhesive sheet for use as a device adhesive layer, and is used to construct an electronic device having a display module.

18. The adhesive sheet according to claim 17, wherein The device adhesive layer is arranged between the transparent electrode and other transparent electrodes arranged in the display module.

19. The adhesive sheet according to claim 17 or 18, wherein a sensor layer constituting a touch sensor is further provided on the display surface side of the display module via the device adhesive layer. The device adhesive layer is composed of the adhesive composition.

20. The adhesive sheet according to claim 17 or 18, wherein The display module comprises a liquid crystal panel, a polarizing plate, a light guide plate and a light source. A polarizing plate and a sensor layer constituting a touch sensor are provided on the display surface side of the display module via the device adhesive layer. The sensor layer and the glass cover are laminated via other device adhesive layers. The device adhesive layer is a layer adjacent to the polarizer, The further device adhesive layer is a layer adjacent to the sensor layer.

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