Adhesive sheet, optical laminate, and image display device

Abstract

Provided is an adhesive sheet suitable for suppressing peeling between members of an image display device in a high-temperature environment. This adhesive sheet (1) has a first surface (1a) and a second surface (1b) facing each other. The creep amount of the adhesive sheet (1) as determined by the following test is 10 [mu] m or more, and the elastic modulus G1 of the first surface (1a) as measured using an atomic force microscope is 1.0 MPa or more. In the test, a load (54) of 500 gf is applied vertically downward in a state in which a test plate (53) is fixed to an adhesive sheet (1) which is adhered to the stainless steel test plate (53) at a joint surface of 10 mm in a longitudinal direction and 10 mm in a transverse direction. The creep amount (offset amount) of the adhesive sheet (1) with respect to the test plate (53) after 3600 seconds from the start of application of the load (54) is measured.

Description

Technical Field

[0001] This invention relates to adhesive sheets, optical laminates, and image display devices. Background Technology

[0002] Various image display devices, such as liquid crystal displays and electroluminescent (EL) displays, generally possess an optical laminate comprising optical films such as polarizing films and an adhesive sheet. The bonding between the optical films contained in the optical laminate, and the bonding between the optical laminate and the image display panel, typically utilizes an adhesive sheet. A typical adhesive sheet is obtained by curing a monomer group containing acrylic monomers, silicone monomers, etc., through polymerization and cross-linking. Patent Document 1 discloses an example of an adhesive sheet.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 3052972 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] In existing image display devices, there is a tendency for delamination to occur between components such as the optical laminate and the image display panel, and between the adhesive sheet and the optical film, in high-temperature environments. According to the research of the inventors, this delamination problem tends to occur more significantly when adhesive sheets are manufactured using a method of curing an adhesive composition by irradiating it with light (photocuring). This problem may also occur when the optical film includes a uniaxially stretched film such as a polarizer, or when the thickness of the adhesive sheet is 50 μm or less (especially 30 μm or less).

[0008] Therefore, the object of the present invention is to provide an adhesive sheet suitable for suppressing peeling between components of an image display device in a high-temperature environment.

[0009] Problem Solving Methods

[0010] The inventors conducted in-depth research and discovered that, for adhesive sheets, creep and surface elastic modulus, which are indicators of strain ease relative to stress, affect the delamination between components in high-temperature environments. Based on the above insights, the inventors conducted further research and thus completed this invention.

[0011] This invention provides an adhesive sheet having a first surface and a second surface that are opposite to each other.

[0012] The creep deformation of the adhesive sheet, as determined by the following tests, is greater than 10 μm.

[0013] The elastic modulus of the first surface, as measured by atomic force microscopy, is greater than or equal to 1.0 MPa.

[0014] Test: For the adhesive sheet that is bonded to a stainless steel test plate with a joint surface of 10mm in length and 10mm in width, a load of 500gf is applied vertically downward with the test plate fixed, and the creep (offset) of the adhesive sheet relative to the test plate is measured 3600 seconds after the load is applied.

[0015] Furthermore, the present invention provides an optical laminate comprising:

[0016] The aforementioned adhesive sheet, and

[0017] An optical film comprising at least one selected from polarizing films and phase difference films.

[0018] Furthermore, the present invention provides an image display device having the aforementioned optical laminate.

[0019] The effects of the invention

[0020] According to the present invention, an adhesive sheet suitable for suppressing peeling between components of an image display device in a high-temperature environment can be provided. Attached Figure Description

[0021] Figure 1 This is a cross-sectional view schematically illustrating an example of the adhesive sheet of the present invention.

[0022] Figure 2A This is a schematic diagram used to illustrate the method for measuring creep in adhesive sheets.

[0023] Figure 2B This is a schematic diagram used to illustrate the method for measuring creep in adhesive sheets.

[0024] Figure 3A This is an example of an atomic force microscope image showing the first surface of the adhesive sheet.

[0025] Figure 3B This is an example of a histogram showing the elastic modulus measured using an atomic force microscope.

[0026] Figure 4 This is an example of an atomic force microscope image showing a cross-section of the adhesive sheet.

[0027] Figure 5A This is a schematic diagram illustrating an example of the method for manufacturing the adhesive sheet of the present invention.

[0028] Figure 5B This is a schematic diagram illustrating an example of the method for manufacturing the adhesive sheet of the present invention.

[0029] Figure 5C This is a schematic diagram illustrating an example of the method for manufacturing the adhesive sheet of the present invention.

[0030] Figure 5D This is a schematic diagram illustrating an example of the method for manufacturing the adhesive sheet of the present invention.

[0031] Figure 5E This is a schematic diagram illustrating an example of the method for manufacturing the adhesive sheet of the present invention.

[0032] Figure 6 This is a cross-sectional view schematically illustrating an example of the optical laminate of the present invention.

[0033] Figure 7 This is a cross-sectional view schematically illustrating an example of the optical laminate of the present invention. Detailed Implementation

[0034] The adhesive sheet of the first embodiment of the present invention has a first surface and a second surface that are opposite to each other.

[0035] The creep deformation of the adhesive sheet, as determined by the following tests, is greater than 10 μm.

[0036] The elastic modulus of the first surface, as measured by atomic force microscopy, is greater than or equal to 1.0 MPa.

[0037] Test: For the adhesive sheet with a joint surface of 10mm x 10mm attached to a stainless steel test plate, a load of 500gf is applied vertically downwards while the test plate is fixed. The creep (offset) of the adhesive sheet relative to the test plate is measured 3600 seconds after the load is applied.

[0038] In a second aspect of the present invention, for example, the adhesive sheet of the first aspect has a first layer and a second layer located on the first layer, wherein the first surface and the surface of the second layer are consistent.

[0039] In the third aspect of the present invention, for example, in the adhesive sheet of the second aspect, the thickness of the second layer is 1.0 μm or less.

[0040] In the fourth aspect of the present invention, for example, in the adhesive sheet of any of the first to third aspects, the creep is 300 μm or less.

[0041] In the fifth aspect of the present invention, for example, in the adhesive sheet of any of the first to fourth aspects, the elastic modulus of the first surface is 10.0 MPa or less.

[0042] In the sixth aspect of the present invention, for example, in the adhesive sheet of any of the first to fifth aspects, the elastic modulus of the second surface described above, as measured by an atomic force microscope, is less than 1.0 MPa.

[0043] In the seventh aspect of the present invention, for example, in the adhesive sheet of any of the first to sixth aspects, the first surface is a surface that has undergone surface modification treatment.

[0044] In the eighth aspect of the present invention, for example, in the adhesive sheet of the seventh aspect, the above-mentioned surface modification treatment is a corona treatment.

[0045] In a ninth aspect of the present invention, for example, the adhesive sheet of any of the first to eighth aspects is formed from an adhesive composition comprising a monomer group and / or a polymer of the monomer group described above.

[0046] In a 10th aspect of the invention, for example, in the adhesive sheet of the 9th aspect, the above-mentioned monomer group comprises (meth)acrylic monomers.

[0047] In the eleventh aspect of the present invention, for example, in the adhesive sheet of the ninth or tenth aspect, the above-mentioned adhesive composition is photocurable.

[0048] In the 12th aspect of the present invention, for example, in the adhesive sheet of any of the 9th to 11th aspects, the solvent content in the adhesive composition is 5% by weight or less.

[0049] In the 13th aspect of the present invention, for example, the thickness of the adhesive sheet in any of the 1st to 12th aspects is 50 μm or less.

[0050] The optical laminate of the 14th embodiment of the present invention comprises:

[0051] Adhesive sheets of any of methods 1 to 13, and

[0052] An optical film comprising at least one selected from polarizing films and phase difference films.

[0053] In the 15th aspect of the present invention, for example, in the optical laminate of the 14th aspect, the first surface of the adhesive sheet is in contact with the optical film.

[0054] In the 16th aspect of the present invention, for example, in the optical laminate of the 14th or 15th aspect, the anchoring force between the adhesive sheet and the optical film is 10.0 N / 25 mm or more.

[0055] The image display device of the 17th embodiment of the present invention includes an optical laminate of any one of the 14th to 16th embodiments.

[0056] The present invention will now be described in detail, but the present invention is not limited to the following embodiments and can be implemented in any way without departing from the spirit of the present invention.

[0057] [Implementation of the Adhesive Sheet]

[0058] An example of the adhesive sheet of this embodiment is shown below. Figure 1 . Figure 1 The adhesive sheet 1 has a first surface 1a and a second surface 1b that are opposite to each other. As an example, the adhesive sheet 1 is attached to the optical film via the first surface 1a and to the image display panel via the second surface 1b.

[0059] The creep of the adhesive sheet 1, as determined by the following tests, is 10 μm or more. Furthermore, the elastic modulus G1 of the first surface 1a, as measured using atomic force microscopy (AFM), is 1.0 MPa or more.

[0060] Test: For adhesive sheet 1, which is bonded to a stainless steel test plate with a joint surface of 10mm x 10mm, a load of 500gf is applied vertically downward with the test plate fixed. The creep (offset) of adhesive sheet 1 relative to the test plate is measured 3600 seconds after the load is applied.

[0061] According to the adhesive sheet 1 of this embodiment, due to the aforementioned creep and elastic modulus G1, peeling between components of the image display device can be suppressed in a high-temperature environment. Specifically, by making the creep 10 μm or more, there is a tendency to suppress peeling between the optical laminate and the image display panel. By making the elastic modulus G1 of the first surface 1a 1.0 MPa or more, there is a tendency to suppress peeling between the adhesive sheet 1 and the optical film. By suppressing peeling between components of the image display device, air intrusion and optical film displacement can be suppressed. Therefore, when using the adhesive sheet 1 of this embodiment, there is a tendency for the image display function of the image display device to be less prone to problems.

[0062] In detail, the creep of adhesive sheet 1 can be evaluated by the following methods (refer to...). Figure 2A and Figure 2BFirst, the adhesive sheet 1 is bonded to the support film 51 with its first surface 1a facing the support film 51 to form a laminate. This laminate is then cut into strips of 10mm x 50mm to form a test piece 52. The support film 51 is configured to suppress deformation of the load-bearing portion of the adhesive sheet 1 under load during testing, thereby allowing for more accurate measurement of creep. The support film 51 can be a resin film, such as polyethylene terephthalate (PET) film. The support film 51 can be an optical film or a laminate containing an optical film. The thickness of the support film 51 is sufficient to prevent deformation under the aforementioned load, for example, 20 to 200 μm. Next, as... Figure 2A and Figure 2B As shown, the test piece 52 is adhered to the surface of the stainless steel test plate 53 using adhesive sheet 1, with a joint surface measuring 10mm in length and 10mm in width. It should be noted that... Figure 2B yes Figure 2A The cross-section BB. The bonding of the test piece 52 to the test plate 53 is carried out in a manner that prevents air bubbles from entering between the test plate 53 and the adhesive sheet 1. After bonding, the plate is placed in an autoclave at 50°C and 5 atmospheres (absolute pressure) for 15 minutes to homogenize the bonding between the test plate 53 and the adhesive sheet 1. Next, the test plate 53 and the test piece 52 are held vertically with the test plate 53 facing upwards and placed in an atmosphere at 25°C for at least 5 minutes. With the test plate 53 fixed, a 500g weight is fixed at the center of the lower end of the test piece 52, and a load 500gf is applied vertically downwards. The creep (offset) of the adhesive sheet 1 relative to the test plate 53 is measured as the amount of weight drop 3600 seconds after the application of the load 54. The amount of weight drop can be measured using a laser displacement gauge. It should be noted that the application of the load 54 is performed in an atmosphere at 25°C.

[0063] As described above, in this embodiment, the creep of the adhesive sheet 1 is 10 μm or more. The creep of the adhesive sheet 1 is preferably 15 μm or more, but can be 20 μm or more, 30 μm or more, 40 μm or more, 50 μm or more, 60 μm or more, 70 μm or more, 80 μm or more, 90 μm or more, 100 μm or more, 110 μm or more, 120 μm or more, and further, 130 μm or more. The greater the creep of the adhesive sheet 1, the more likely it is to suppress peeling between components of the image display device, particularly between the optical laminate and the image display panel, in high-temperature environments. However, if the creep of the adhesive sheet 1 is too large, there is a tendency for cracking (paste cracking) to occur inside the adhesive sheet 1 in high-temperature environments. According to the research of the inventors, cracking of the adhesive sheet 1 in high-temperature environments is particularly prone to occur in adhesive sheets 1 produced by a method of curing the adhesive composition by irradiating it with light (photocuring method). From the viewpoint of suppressing cracking of the adhesive sheet 1 in a high-temperature environment, the upper limit of the creep of the adhesive sheet 1 is, for example, 500 μm or less, and can be 400 μm or less, 300 μm or less, 250 μm or less, 200 μm or less, 180 μm or less, 160 μm or less, and further can be 150 μm or less.

[0064] Specifically, the elastic modulus G1 of the first surface 1a can be evaluated using the following method. First, a test piece is prepared by cutting the adhesive sheet 1 to a size of approximately 0.8 cm in length and 0.5 cm in width. Next, the test piece is fixed to the sample stage using a conductive double-sided tape. At this point, the test piece is positioned such that the second surface 1b of the test piece faces the sample stage, and the first surface 1a is exposed to the outside. The test piece is left to stand for at least 1 hour to allow it to stabilize.

[0065] Next, using AFM, for a 20 μm longitudinal × 20 μm transverse range on the first surface 1a of the test piece, the number of measurement points is 2. 8 The elastic modulus was determined using the method described in (256). The interval between adjacent measurement points was adjusted to approximately 1 μm. The elastic modulus was measured, for example, over a lengthwise × widthwise area of ​​20 μm across the entire first surface 1a of the test specimen. The elastic modulus can be determined using a load-displacement curve obtained from a force curve and the JKR two-point method. As an AFM (Automatic Measurement Method), a commercially available scanning probe microscope (e.g., the MFP-3D Stand Alone manufactured by ASYLUM RESEARCH) can be used. Details of the elastic modulus measurement conditions are described below.

[0066] • Measurement conditions

[0067] Measurement Mode: Force Mode

[0068] Cantilever: Olympus, OMCL-AC240TS (Resonant frequency: 75kHz, Spring constant: 1.7N / m, Tip shape: Sphere (radius 10nm), Poisson's ratio: 0.5)

[0069] Scan range: 20μm (vertical) × 20μm (horizontal)

[0070] Number of data read: 16 × 16 (256)

[0071] Indentation velocity: 1.98 μm / s

[0072] Trigger point: 0.05V

[0073] Measurement temperature: 25℃

[0074] Through the above measurements, elastic modulus data can be obtained for each of multiple locations on the first surface 1a of the test piece. By mapping this data, the following can be obtained: Figure 3A An AFM image as shown is presented. In this AFM image, each pixel is assigned hue visual information based on the value of the elastic modulus. The size of a pixel in the AFM image corresponds to the size of the tip of the cantilever. The number of pixels constituting the AFM image is consistent with the number of measurement points.

[0075] Next, a histogram of the elastic modulus with a width of 0.02 MPa is constructed. Figure 3B In this histogram, the horizontal axis represents the elastic modulus, and the vertical axis represents the degree (the number of measurement points). The elastic modulus (mode value) corresponding to the maximum degree value M in the histogram is determined as the elastic modulus G1 of the first surface 1a.

[0076] It should be noted that, in this embodiment, the number of peaks present in the histogram generated by the above method is preferably one. As an example, in... Figure 3B The image shows a single peak P. Peak P is typically unimodal. However, multiple peaks, or multimodal peaks, can also exist in the histogram.

[0077] As described above, in this embodiment, the elastic modulus G1 of the first surface 1a is 1.0 MPa or higher. For example, when the first surface 1a of the adhesive sheet 1 is in contact with the optical film, by making the elastic modulus G1 1.0 MPa or higher, there is a tendency to adjust the anchoring force between the adhesive sheet 1 and the optical film to a sufficiently large value. The elastic modulus G1 is preferably 1.1 MPa or higher, and can be 1.2 MPa or higher, 1.3 MPa or higher, 1.4 MPa or higher, 1.5 MPa or higher, 1.6 MPa or higher, 1.7 MPa or higher, 1.8 MPa or higher, and further can be 1.9 MPa or higher. The upper limit of the elastic modulus G1 is not particularly limited, for example, it is 10.0 MPa or lower, it can be 5.0 MPa or lower, 3.0 MPa or lower, and further can be 2.0 MPa or lower.

[0078] It should be noted that the elastic modulus G2 of the second surface 1b measured using AFM is not particularly limited, but is preferably smaller than the elastic modulus G1 described above. The elastic modulus G2 may be less than 1.0 MPa, and can be 0.9 MPa or less, 0.8 MPa or less, or even 0.7 MPa or less. The lower limit of the elastic modulus G2 of the second surface 1b is, for example, 0.1 MPa or more, and can be 0.3 MPa or more, or even 0.5 MPa or more. However, depending on the circumstances, the elastic modulus G2 of the second surface 1b may also be 1.0 MPa or more, falling within the range described above for the elastic modulus G1. The elastic modulus G2 of the second surface 1b can be measured using the same method as the elastic modulus G1 of the first surface 1a.

[0079] The first surface 1a of the adhesive sheet 1 is, for example, a surface that has undergone surface modification treatment. The first surface 1a that has undergone surface modification treatment tends to have a high elastic modulus G1 as described above. On the other hand, the second surface 1b of the adhesive sheet 1 is preferably not subjected to surface modification treatment. Examples of surface modification treatments include corona treatment, plasma treatment, excimer laser treatment, flame treatment, etc. The first surface 1a is preferably subjected to corona treatment as a surface modification treatment.

[0080] Surface modification treatment can be carried out in an inert gas atmosphere. By performing surface modification treatment under conditions where the oxygen concentration is reduced using an inert gas, the risk of ignition of residual monomers can be reduced. Specifically, it is preferable to perform surface modification treatment at an oxygen concentration of 8% by volume or less, more preferably 6% by volume or less, and even more preferably 3% by volume or less. If the oxygen concentration is too low, the introduction of functional groups to the surface of the adhesive sheet 1 through surface modification treatment may become insufficient. Therefore, the oxygen concentration is preferably 0.01% by volume or more, more preferably 0.1% by volume or more, and particularly preferably 0.5% by volume or more. Specific examples of inert gases include nitrogen and argon. Surface modification treatment can be carried out at atmospheric pressure (1 atmosphere).

[0081] The conditions for surface modification treatment using corona treatment are expressed by the discharge amount, for example, 1 W / m. 2 For min and above, it can be 10W / m 2 ·min or above, 20W / m 2 ·min or above, 30W / m 2 ·min or above, 40W / m 2 ·min or above, 50W / m 2 ·min or higher, and can reach 60W / m 2 • min or more. However, when corona treatment is applied to the first surface 1a of the adhesive sheet 1, if the discharge amount is too large, uneven elastic modulus may sometimes occur within the first surface 1a, and the elastic modulus G1 determined by the above method may not increase sufficiently. From the viewpoint of adjusting the elastic modulus G1 of the first surface 1a to an appropriate value, the discharge amount is preferably 400 W / m. 2 For min and below, it can be 350W / m 2 ·min or less, 300W / m 2 ·min or less, 250W / m 2 ·min or less, 200W / m 2 ·min or less, 150W / m 2 ·min or less, 100W / m 2 Below min, and thus up to 80W / m 2 ·min and below.

[0082] like Figure 1 As shown, the adhesive sheet 1 preferably has a first layer 5 and a second layer 6 located on the first layer 5. The second layer 6 is typically in direct contact with the first layer 5. The second layer 6 can completely or partially cover the surface of the first layer 5. As an example, the first surface 1a of the adhesive sheet 1 coincides with the surface 6a of the second layer 6, and the second surface 1b of the adhesive sheet 1 coincides with the surface 5a of the first layer 5. Typically, the second layer 6 is a layer with a higher elastic modulus and a smaller thickness than the first layer 5. It should be noted that the adhesive sheet 1 may not have the laminated structure of the first layer 5 and the second layer 6, and may be a single-layer film, provided that the creep and the elastic modulus G1 of the first surface 1a are adjusted to the ranges described above.

[0083] As described below, the first layer 5 and the second layer 6 can be manufactured, for example, by surface modification of the cured sheet formed from the adhesive composition. Specifically, the second layer 6, with a high elastic modulus, can be formed in the surface-modified portion, while the first layer 5 is formed in the remaining portion. It can be considered that the first layer 5 and the second layer 6 thus manufactured have the same composition and are formed from the same adhesive composition.

[0084] The thickness of the first layer 5 is, for example, less than 500 μm, but can be less than 250 μm, less than 150 μm, less than 100 μm, less than 50 μm, less than 30 μm, less than 25 μm, and further less than 20 μm. The lower limit of the thickness of the first layer 5 is, for example, more than 2 μm, and can be more than 5 μm. The thickness of the first layer 5 can be calculated, for example, based on the thickness of the adhesive sheet 1 and the thickness of the second layer 6.

[0085] The thickness of the second layer 6 is, for example, 1.0 μm or less, but can be 0.8 μm or less, 0.5 μm or less, 0.4 μm or less, 0.3 μm or less, 0.2 μm or less, and further, 0.1 μm or less. There is no particular limitation on the lower limit of the thickness of the second layer 6, but it can be, for example, 0.001 μm or more. The thickness of the second layer 6 tends to be sufficiently small compared to the first layer 5.

[0086] The thickness of the second layer 6 can be measured, for example, by the following method. First, the adhesive sheet 1 is bonded to the support film with the first surface 1a of the adhesive sheet 1 facing the support film to form a laminate. An optical film or the like can be used as the support film. After freezing the laminate, it is cut along the thickness direction using an ultramicrotome to obtain a test piece. This test piece is a slice with a thickness of approximately 200 nm, and its main surface (the surface with the largest area) is consistent with the cross-section of the laminate. Next, the test piece is fixed onto a silicon wafer and left to stand overnight to stabilize it.

[0087] Next, using AFM, a 1μm x 1μm area near the interface between the adhesive sheet 1 and the support film on the main surface of the test piece was measured, so that the number of measurement points was 2. 14 The elastic modulus was determined using the method described in (16384). The interval between adjacent measurement points was adjusted to approximately 8 nm. The elastic modulus was measured, for example, over a 1 μm x 1 μm area on the main surface of the test specimen. The elastic modulus can be determined using a load-displacement curve obtained from a force curve and the JKR two-point method. As an AFM (Advanced Dynamics Measuring Instrument), a commercially available scanning probe microscope (e.g., the MFP-3D StandAlone manufactured by ASYLUM RESEARCH) can be used. Details of the elastic modulus measurement conditions are described below.

[0088] • Measurement conditions

[0089] Measurement Mode: Force Mode

[0090] Cantilever: Olympus, OMCL-AC240TS (Resonant frequency: 75kHz, Spring constant: 1.7N / m, Tip shape: Sphere (radius 10nm), Poisson's ratio: 0.5)

[0091] Scan range: 1μm (vertical) × 1μm (horizontal)

[0092] Number of data read: 128 × 128 (16384)

[0093] Indentation velocity: 1.98 μm / s

[0094] Trigger point: 0.05V

[0095] Measurement temperature: 25℃

[0096] Through the above measurements, elastic modulus data can be obtained for each of multiple locations on the main surface of the test piece. By mapping this data, the following can be obtained: Figure 4 An AFM image as shown is presented. In this AFM image, visual information such as hue is assigned to each pixel based on the value of the elastic modulus. The size of a pixel in the AFM image corresponds to the size of the tip of the cantilever. The number of pixels constituting the AFM image is consistent with the number of measurement points.

[0097] like Figure 4 As shown, based on the AFM image, regions with lower elastic modulus (layer 1, 5) and higher elastic modulus (layer 2, 6) can be identified in the area where adhesive sheet 1 exists. It should be noted that the region with higher elastic modulus exists near the interface between adhesive sheet 1 and the support film. Based on the obtained AFM image, the thickness of layer 2, 6 can be determined. Specifically, the distance between layer 1, 5 and the support film in the AFM image can be measured at any number of points (e.g., more than 5 points), and the average of the obtained values ​​is taken as the thickness of layer 2, 6.

[0098] The thickness of the adhesive sheet 1 is, for example, 500 μm or less, but can be 250 μm or less, 150 μm or less, 100 μm or less, 50 μm or less, 30 μm or less, 25 μm or less, and further can be 20 μm or less. The lower limit of the thickness of the adhesive sheet 1 is, for example, 2 μm or more, but can be 5 μm or more.

[0099] (Adhesive composition)

[0100] The adhesive sheet 1 is formed, for example, from an adhesive composition comprising a monomer group and / or a polymer of that monomer group. More specifically, the adhesive sheet 1 can be manufactured by surface modification of a cured sheet formed from the aforementioned adhesive composition. The adhesive composition is preferably a photocurable adhesive composition that cures upon exposure to light (a light-curing composition). However, the adhesive composition can also be a thermosetting adhesive composition that cures upon exposure to heat.

[0101] It should be noted that, generally speaking, adhesive sheets can be manufactured using, for example, the following thermosetting method. First, an adhesive composition is prepared by combining a crosslinking agent with a polymer made by polymerizing monomers in an organic solvent. This adhesive composition is then applied to a substrate such as a release liner, and the organic solvent is removed by heating to form a sheet. Heating and curing are then performed as needed to complete crosslinking, thereby manufacturing the adhesive sheet. In this manufacturing process, the heat required for solvent removal and curing necessitates the combustion of large quantities of fuels such as LNG. Furthermore, directly releasing the removed organic solvents into the atmosphere poses a serious risk of adverse environmental impact. Therefore, in most cases, the organic solvents are burned in a deodorizing furnace before release. In this case, not only does the fuel used for combustion in the deodorizing furnace become more necessary, but the organic solvents themselves are also converted into CO2 and emitted into the atmosphere during combustion, making it a manufacturing process with very high CO2 emissions.

[0102] In recent years, climate change caused by greenhouse gases has become an urgent issue, and governments worldwide have set numerical targets to reduce CO2 emissions. Therefore, manufacturing processes that do not use organic solvents and have low CO2 emissions are preferred in the production of adhesive sheets. Compared to thermosetting methods, photopolymerization methods, which utilize light to produce adhesive sheets, tend to reduce the amount of adhesive sheet required for formation and CO2 emissions.

[0103] According to the research of the inventors, conventionally, when adhesive sheets formed from photocurable adhesive compositions are used, there is a tendency for peeling between components of the image display device, particularly between the adhesive sheet and the optical film, to easily occur compared to when adhesive sheets formed from thermosetting adhesive compositions are used. This tendency can be presumed to be due to the following reason: when adhesive sheets formed from thermosetting adhesive compositions are bonded to the optical film, the curing of the adhesive sheet proceeds further on the surface of the optical film; on the other hand, in adhesive sheets formed from photocurable adhesive compositions, curing hardly occurs after bonding to the optical film. In this embodiment, by adjusting the creep and the elastic modulus G1 of the first surface 1a to the range described above, even when the adhesive sheet 1 is formed from a photocurable adhesive composition, the tendency for peeling between components of the image display device can be sufficiently suppressed.

[0104] As described above, the adhesive composition comprises a monomer group and / or a polymer of that monomer group. The monomer group, for example, comprises (meth)acrylic acid monomers. The content of the (meth)acrylic acid component in the adhesive composition, i.e., the (meth)acrylic acid monomer and its polymer, can be 50% by weight or more, 60% by weight or more, 70% by weight or more, and further, 80% by weight or more. In this case, an acrylic adhesive sheet 1, mainly composed of (meth)acrylic acid polymers and their crosslinks, can be formed. However, the adhesive composition is not limited to the above examples. In this specification, (meth)acrylic acid refers to acrylic acid and methacrylic acid. (Meth)acrylate refers to acrylate and methacrylate.

[0105] Examples of (meth)acrylic acid monomers are alkyl (meth)acrylates having an alkyl group having 1 to 20 carbon atoms in the side chain. The alkyl group may have 7 or fewer carbon atoms, 6 or fewer, 5 or fewer, and further, 4 or fewer. The alkyl group may be linear or branched. Examples of alkyl methacrylates are methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, sec-butyl methacrylate, tert-butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, n-hexyl methacrylate, isohexyl methacrylate, isohexyl methacrylate, 2-ethylhexyl methacrylate, n-octyl methacrylate, isooctyl methacrylate, n-nonyl methacrylate, isononyl methacrylate, n-decyl methacrylate, isodecyl methacrylate, n-dodecyl methacrylate (laurate methacrylate), n-tridecyl methacrylate, n-tetradecyl methacrylate, n-pentadecanyl methacrylate, n-hexadecyl methacrylate, hexadecyl methacrylate, heptadecanyl methacrylate, and octadecyl methacrylate. Alkyl methacrylates can be n-butyl methacrylates.

[0106] The amount of alkyl (meth)acrylate in 100 parts by weight of monomer group is, for example, 40 parts by weight or more, or 50 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, 80 parts by weight or more, 85 parts by weight or more, 90 parts by weight or more, and further, 95 parts by weight or more. It should be noted that when calculating the amount of a specific monomer, the weight of the polymer is converted to the weight of each monomer before polymerization.

[0107] The monomer group may contain carboxyl-containing monomers. Carboxyl-containing monomers may be (meth)acrylic acid monomers; in other words, (meth)acrylic acid monomers may include carboxyl-containing monomers. Examples of carboxyl-containing monomers are (meth)acrylic acid, carboxyethyl (meth)acrylic acid, carboxypentyl (meth)acrylic acid, itaconic acid, maleic acid, fumaric acid, and crotonic acid. The amount of carboxyl-containing monomer in 100 parts by weight of the monomer group may be, for example, 10 parts by weight or less, and may be 9 parts by weight or less, 8 parts by weight or less, 7 parts by weight or less, 6 parts by weight or less, 5 parts by weight or less, 4.8 parts by weight or less, 4 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, and further may be 0.5 parts by weight or less. The lower limit of the amount may be, for example, 0.1 parts by weight or more, and depending on the circumstances, may also be 0.5 parts by weight or more. The monomer group may also not contain carboxyl-containing monomers.

[0108] The monomer group may include hydroxyl-containing monomers. Hydroxyl-containing monomers may be (meth)acrylate monomers; in other words, (meth)acrylate monomers may include hydroxyl-containing monomers. Hydroxyl-containing monomers can contribute to improved cohesiveness of the adhesive sheet. Examples of hydroxyl-containing monomers are 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and methyl (4-hydroxymethylcyclohexyl)acrylate. Preferably, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are hydroxyl-containing monomers. The amount of hydroxyl-containing monomer in 100 parts by weight of the monomer group may be, for example, 20 parts by weight or less, but can be 15 parts by weight or less, 10 parts by weight or less, 7.5 parts by weight or less, 5 parts by weight or less, 4 parts by weight or less, 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, and further, 0.5 parts by weight or less. The lower limit of the amount of the compound is, for example, 0.01 parts by weight or more, 0.03 parts by weight or more, and further, 0.05 parts by weight or more. The monomer group may also not contain hydroxyl-containing monomers.

[0109] The monomer group may include ether-containing monomers. These ether-containing monomers can be (meth)acrylic acid monomers; in other words, (meth)acrylic acid monomers may include ether-containing monomers. Ether-containing monomers can contribute to improved anchoring strength between the adhesive sheet 1 and the optical film.

[0110] The ether-containing monomer is preferably an alkoxy-containing monomer. Examples of alkoxy-containing monomers include, for instance, the epoxide alkane adduct shown in formula (A). R in formula (A) 1 It is a hydrogen atom or a methyl group. R in formula (A) 2 It is an alkyl group. Alkyl groups can be straight-chain or branched. R 2 Preferably, it is a straight-chain alkyl group. R2 Examples include methyl and ethyl. In formula (A), n is an integer from 1 to 30, preferably an integer from 1 to 12, and can be an integer from 1 to 5.

[0111] [Chemical Formula 1]

[0112]

[0113] Examples of the epoxyalkane adducts shown in formula (A) are 2-methoxyethyl acrylate, 2-ethoxyethyl acrylate, 2-(2-ethoxyethoxy)ethyl acrylate, methoxytriethylene glycol (meth)acrylate and methoxypolyethylene glycol (meth)acrylate, preferably 2-methoxyethyl acrylate (MEA).

[0114] The ether-containing monomer is not limited to the above-mentioned epoxide alkane adducts. The ether-containing monomer may have a cyclic structure, which may contain an ether group. Examples of cyclic structures containing an ether group include tetrahydrofuran rings and dialkyl rings. Examples of ether-containing monomers with cyclic structures are cyclic trimethylolpropane methyl acetal (meth)acrylate and tetrahydrofurfuryl (meth)acrylate.

[0115] The amount of the ether-containing monomer in 100 parts by weight of the monomer group may be, for example, 1 part by weight or more, but can be 5 parts by weight or more, 10 parts by weight or more, 20 parts by weight or more, 25 parts by weight or more, 30 parts by weight or more, 40 parts by weight or more, 50 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, 80 parts by weight or more, and further can be 90 parts by weight or more. The upper limit of the amount is, for example, 99 parts by weight or less, and depending on the circumstances, it can be 50 parts by weight or less. The monomer group may also not contain any ether-containing monomer.

[0116] The monomer group may include nitrogen-containing monomers. A nitrogen-containing monomer is a monomer having at least one nitrogen atom within a molecule (one molecule). It should be noted that, in this specification, monomers having both hydroxyl and nitrogen atoms within a molecule are classified as nitrogen-containing monomers. Monomers having both carboxyl and nitrogen atoms within a molecule are classified as carboxyl-containing monomers.

[0117] As nitrogen-containing monomers, N-vinylcyclic amides, (meth)acrylamides, etc., are preferred. It should be noted that nitrogen-containing monomers can be used alone or in combination of two or more.

[0118] N-vinyl cyclic amides are preferably represented by the following formula (B).

[0119] [Chemical Formula 2]

[0120]

[0121] In equation (B), R1 It is a divalent organic group, preferably a divalent saturated hydrocarbon group or an unsaturated hydrocarbon group, more preferably a divalent saturated hydrocarbon group (e.g., an alkylene group with 3 to 5 carbon atoms). It should be noted that formula (B) represents N and R. 1 A ring structure is formed through direct bonding of single bonds.

[0122] As the N-vinyl cyclic amide represented by formula (B), N-vinyl-2-pyrrolidone (NVP), N-vinyl-2-piperidone, N-vinyl-2-caprolactam, N-vinyl-3-morpholinone, N-vinyl-1,3-pyrazin-2-one, N-vinyl-3,5-morpholinedione, etc., are preferred, N-vinyl-2-pyrrolidone and N-vinyl-2-caprolactam are more preferred, and N-vinyl-2-pyrrolidone is even more preferred.

[0123] Examples of (meth)acrylamides include: (meth)acrylamide, N-alkyl (meth)acrylamide, N,N-dialkyl (meth)acrylamide, etc. Examples of N-alkyl (meth)acrylamides include: N-ethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-n-butyl (meth)acrylamide, N-octylacrylamide, etc. N-alkyl (meth)acrylamides also include (meth)acrylamides containing an amino group, such as dimethylaminoethyl (meth)acrylamide, diethylaminoethyl (meth)acrylamide, and dimethylaminopropyl (meth)acrylamide.

[0124] Examples of N,N-dialkyl(meth)acrylamides include: N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N,N-dipropyl(meth)acrylamide, N,N-diisopropyl(meth)acrylamide, N,N-di-n-butyl(meth)acrylamide, N,N-di-tert-butyl(meth)acrylamide, etc.

[0125] (Methacrylamide) also includes, for example, various N-hydroxyalkyl (meth)acrylamides. Examples of N-hydroxyalkyl (meth)acrylamides include: N-hydroxymethyl (meth)acrylamide, N-(2-hydroxyethyl) (meth)acrylamide, N-(2-hydroxypropyl) (meth)acrylamide, N-(1-hydroxypropyl) (meth)acrylamide, N-(3-hydroxypropyl) (meth)acrylamide, N-(2-hydroxybutyl) (meth)acrylamide, N-(3-hydroxybutyl) (meth)acrylamide, N-(4-hydroxybutyl) (meth)acrylamide, N-methyl-N-2-hydroxyethyl (meth)acrylamide, etc.

[0126] (Methacrylamide) also includes, for example, various N-alkoxyalkyl (meth)acrylamides. Examples of N-alkoxyalkyl (meth)acrylamides include, for example, N-methoxymethyl (meth)acrylamide, N-butoxymethyl (meth)acrylamide, etc.

[0127] Examples of nitrogen-containing monomers other than N-vinylcyclic amides and (meth)acrylamide include: aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, tert-butylaminoethyl (meth)acrylate, etc.; cyano monomers such as acrylonitrile and methacrylonitrile; (meth)acryloylmorpholine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazolium, N-vinylpyrazine, N-vinylmorpholine, N-vinylpyrazole, vinylpyridine, vinylpyrimidine, vinylpyrazole, vinylisopyrazole, vinylthiazole, vinylisothiazole, vinylpyridazine, (meth)acryloylpyrrolidone, (meth)acryloylpyrrolidine, (meth)acryloylpiperidine, N-methylvinyl... Monomers containing heterocyclic compounds such as pyrrolidone; maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, and N-phenylmaleimide; itaconimide monomers such as N-methylitconimide, N-ethylitconimide, N-butylitconimide, N-octylitconimide, N-2-ethylhexylitconimide, N-laurylitconimide, and N-cyclohexylitconimide; succinimide monomers such as N-(meth)acryloyloxymethylenesuccinimide, N-(meth)acryloyl-6-oxohexamethylenesuccinimide, and N-(meth)acryloyl-8-oxooctamethylenesuccinimide; and isocyanate monomers such as 2-(meth)acryloyloxyethyl isocyanate.

[0128] The content of nitrogen-containing monomers in the monomer group may be, for example, 40% by weight or less, but can be 35% by weight or less, 30% by weight or less, 25% by weight or less, 20% by weight or less, 15% by weight or less, 10% by weight or less, and further, 8% by weight or less. The lower limit of the content may be, for example, 1% by weight or more, 3% by weight or more, and further, 5% by weight or more. The monomer group may also not contain nitrogen-containing monomers.

[0129] The monomer group preferably includes carboxyl-containing monomers and / or nitrogen-containing monomers, more preferably both carboxyl-containing monomers and nitrogen-containing monomers. In particular, if both nitrogen-containing monomers, especially both nitrogen-containing monomers and carboxyl-containing monomers, are present in the photopolymerization system, a tendency for the polymer molecular weight to increase is observed. This tendency may be facilitated by the increase in viscosity of the polymerization system caused by hydrogen bonding, which inhibits the stopping reaction between the growth ends of the polymer, and by the tendency for monomers to remain at the ends of the growth chains. It should be noted that the molecular weight of the polymer may affect the creep of the adhesive sheet 1.

[0130] The aforementioned monomers may be included in the adhesive composition in the form of a polymer. When the adhesive composition is photocurable, the polymer is preferably a partial polymer. The partial polymer can be any polymer among homopolymers and copolymers. The partial polymer can contribute to the stable formation of the coating layer described later by moderately increasing the viscosity of the adhesive composition.

[0131] The adhesive composition may contain a photopolymerization initiator. Examples of photopolymerization initiators include photoradiogenin generators that produce free radicals upon light irradiation. In photopolymerization initiators, the absorptivity for light at a wavelength of 340 nm is, for example, 0.1 L / (g·cm) or more, and can be 0.5 L / (g·cm) or more, 1.0 L / (g·cm) or more, 3.0 L / (g·cm) or more, and further, 5.0 L / (g·cm) or more. There is no particular upper limit to this absorptivity, and it may be, for example, 50 L / (g·cm) or less. The absorptivity of the photopolymerization initiator is calculated based on the absorbance of a 0.01 mg / mL methanol solution obtained by measuring the absorbance using a visible-ultraviolet spectrophotometer with a quartz cell having an optical path length of 1 cm.

[0132] Examples of photopolymerization initiators include benzoin methyl ether, benzoin isopropyl ether, benzoin dimethyl ether, and other benzoin ethers; substituted benzoin ethers such as anisole methyl ether; substituted acetophenones such as 2,2-diethoxyacetophenone and 2,2-dimethoxy-2-phenylacetophenone; 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methylphenylacetone, 2-hydroxy-4'-(2-hydroxyethoxy)-2-methylphenylacetone, and 2,2'-dihydroxy-2,2'-dimethyl-1,1'-[methylenebis(4,1] α-hydroxyalkyl phenyl ketones such as bis(propane-1-one); substituted α-ol ketones such as 2-methyl-2-hydroxyphenylacetone; aromatic sulfonyl chlorides such as 2-naphthalenesulfonyl chloride; photoactive oximes such as 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime; benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3',4,4'-tetra(tert-butyl) Benzophenone compounds such as carbonyl peroxide (BPK); thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-diethylthioxanthone, and other thioxanthone compounds; 2,4,6-trichloro-triazine, 2-phenyl-4,6-bis(trichloromethyl)-triazine, 2-(p-methoxyphenyl)-4,6-bis(trichloromethyl)-triazine, 2-(p-tolyl)-4,6-bis(trichloromethyl)-triazine, 2-piperyl-4 Triazine compounds such as 6-bis(trichloromethyl)-triazine, 2,4-bis(trichloromethyl)-6-styryl-triazine, 2-(naphthyl-1-yl)-4,6-bis(trichloromethyl)-triazine, 2-(4-methoxy-naphthyl-1-yl)-4,6-bis(trichloromethyl)-triazine, 2,4-trichloromethyl-(piperyl)-6-triazine, and 2,4-trichloromethyl-(4'-methoxystyryl)-6-triazine; 1,2-octanedione, 1-[4-(phenylthio)-, Oxime esters such as 2-(O-benzoyl oxime) and O-(acetyl)-N-(1-phenyl-2-oxo-2-(4'-methoxy-naphthyl)ethoxy)hydroxylamine; phosphine compounds such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide and 2,4,6-trimethylbenzoyl diphenylphosphine oxide; quinone compounds such as 9,10-phenanthroquinone, camphorquinone, and ethylanthraquinone; borate esters; carbazole compounds; imidazole compounds; and titanium decene compounds. The adhesive composition may contain one or more photopolymerization initiators. It should be noted that α-hydroxyalkyl phenyl ketones tend to have high absorption of light at wavelengths of 340±10 nm.

[0133] Another example of a photopolymerization initiator is a compound having the following chemical structure (hereinafter referred to as chemical structure X) in the molecule as shown in formula (1).

[0134] [Chemical Formula 3]

[0135]

[0136] R in equation (1) above 1 and R 2 Each is independently a C1-C8 alkyl group; the hydrogen atom is surrounded by -OH, C1-C4 alkoxy, -CN, or -COOR. 51 -OOCR 52 , or -NR 53 R 54 Substitutionalized C1-C4 alkyl groups; C3-C6 alkenyl groups; or -CH2-C6H4-R 55 R 1 and R 2 The alkylene groups can be optionally bonded together to form C2-C9 alkylene groups, or C3-C6 oxoalkylene groups, or azaalkylene groups. 51 It is a C1-C8 alkyl group. R 52 It is a C1-C4 alkyl group. R 53 and R 54 Each is independently a hydrogen atom or a C1-C12 alkyl group; the hydrogen atom is selected from -OH, C1-C4 alkoxy, -CN, and -COOR. 59 It is a C2-C4 alkyl group formed by substitution of at least one group; a C3-C5 alkenyl group; or a cyclohexyl group. R 53 and R 54 It can also be mutually bonded and optionally -O- or -N(R) 60 )- Discontinuous C3~C9 alkylene groups. R 55 It is a C1-C4 alkyl group. R 59 It is a C1-C4 alkyl group. R 60 It consists of hydrogen atoms, C1-C4 alkyl groups, allyl groups, C1-C4 hydroxyalkyl groups, and -CH2CH2-COOR groups. 61 Or -CH2CH2CN. R 61 It is a C1 to C4 alkyl group.

[0137] X is -OR 56 , or -NR 57 R 58 R 56 For hydrogen atoms, -SiR 62 3. C1-C8 alkyl groups, or C3-C6 alkenyl groups. R 57 and R 58 It is a C1-C12 alkyl group; the hydrogen atom is selected from -OH, C1-C4 alkoxy, -CN and -COOR. 63 It is a C2-C4 alkyl group formed by substitution of at least one group; a C3-C5 alkenyl group; or a cyclohexyl group. R57 and R 58 It can also be mutually bonded and optionally -O- or -N(R) 64 )- Discontinuous C3~C9 alkylene groups. R 62 It is a C1-C6 alkyl group. R 63 It is a C1-C4 alkyl group. R 64 It consists of hydrogen atoms, C1-C4 alkyl groups, allyl groups, C1-C4 hydroxyalkyl groups, and -CH2CH2-COOR groups. 65 Or -CH2CH2CN. R 65 It is a C1 to C4 alkyl group.

[0138] Chemical structure X can be bonded via a carbon atom represented by * in formula (1) to a hydrogen atom or a substitution structure of hydrogen atoms.

[0139] In the description of Formula (1), alkyl, alkoxy, alkenyl, alkylene, oxoalkylene, aziralkylene, and hydroxyalkyl can be either unbranched or branched. Furthermore, including the description of Formula (1), the reference to "Cn1~Cn2" (where n1 and n2 are natural numbers) in this specification refers to the number of carbon atoms being in the range of n1~n2.

[0140] R 1 and R 2 Each can be an alkyl group (C1-C8) or an alkenyl group (C3-C6), and can be an alkyl group (C1-C8). R 1 and R 2 Each can be an alkyl group that is C1 to C4, or an alkyl group that is C1 to C3, or an alkyl group that is C1 to C2. 1 and R 2 It can be methyl.

[0141] R 1 and R 2 They can be the same.

[0142] X can be -OR 56 R 56 It can be a hydrogen atom or a C1-C8 alkyl group, which can also be a hydrogen atom. In other words, X can be -OH.

[0143] R 1 R 2 And X can take the above preferred examples in any combination.

[0144] Chemical structure X can be the structure shown in formula (2). In chemical structure X of formula (2), in the case of a substitution structure where a carbon atom represented by * is bonded to a hydrogen atom, this substitution structure is similar to -COCR in formula (2). 1 XR 2The radical is in the para position relative to the benzene ring in chemical structure X.

[0145] [Chemical Formula 4]

[0146]

[0147] Photopolymerization initiators can be compounds that have two or more chemical structures X within a single molecule.

[0148] The photopolymerization initiator can be a compound represented by formula (3). The compound of formula (3) has two chemical structures X within one molecule. Each of the two chemical structures X is located at one end of the molecule of the photopolymerization initiator. More specifically, the two chemical structures X are bonded to each other through -A- and via the carbon atoms of the phenylene group indicated by * above.

[0149] [Chemical Formula 5]

[0150]

[0151] R in equation (3) 1 'and R 2 'Each is independent and independent of R' 1 and R 2 The land can be used as R 1 and R 2 The group taken. R 1 'and / or R 2 'Can be used with R 1 and / or R 2 Same. R 1 R 2 R 1 'and R 2 'They can all be the same.'

[0152] In equation (3), X' is independent of X in equation (1) and can be a group that can be taken as X. X' and X can be the same.

[0153] A is -O-, -CYR 3 - or -C(CH3)R 4 .

[0154] Y represents a hydrogen atom, -Cl, -Br, or -OR. 71 -NR 72 R 73 、or -SR 74 R 3 It is a hydrogen atom, a C1-C8 alkyl group, a C3-C6 alkenyl group, a benzyl group, or a -CH2-C6H4-R group. 75 , or phenyl. R 4It is a C1 to C6 alkyl or alkylene group, which is bonded to the carbon atom of the phenylene group of the compound of formula (3).

[0155] R 71 For hydrogen atoms, -Si(R) 76 3. C1~C12 alkyl, C2~C18 acyl, -CO-NH-R 77 C2-C20 hydroxyalkyl, C2-C20 methoxyalkyl, 3-R 78 -2-hydroxypropyl, 3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxyl]propyl, 2,3-dihydroxypropyl, or C2-C21 hydroxyalkyl groups whose carbon chains are interrupted by 1-9 oxygen atoms, or C3-C25 alkyl groups. 72 and R 73 Each is independently a C1-C12 alkyl group; the hydrogen atom is selected from -OH, C1-C4 alkoxy groups, -CN, and -COOR. 79 It is a C2-C4 alkyl group formed by substitution of at least one group; a C3-C5 alkenyl group; a cyclohexyl group; or a C7-C9 phenylalkyl group. R 72 and R 73 Also optionally mutually bonded and optionally subject to -O- or -N(R) 80 )- Discontinuous C3~C9 alkylene groups. R 74 It is a C1-C18 alkyl, hydroxyethyl, 2,3-dihydroxypropyl, cyclohexyl, benzyl, phenyl, C1-C12 alkylphenyl, -CH2-COOR 81 -CH2CH2-COOR 82 、or -CH(CH3)-COOR 83 R 75 It is a C1-C4 alkyl group. R 76 It is a C1-C6 alkyl group. R 77 It is a C1-C12 alkyl group. R 78 It is an alkoxy group with C1~C18 atoms. R 79 It is a C1-C4 alkyl group. R 80 It consists of hydrogen atoms, C1-C4 alkyl groups, allyl groups, benzyl groups, C1-C4 hydroxyalkyl groups, and -CH2CH2-COOR groups. 84 Or -CH2CH2CN. R 81 R 82 and R 83 Each is an alkyl group, independently of the C1 to C18 group. R 84 It is a C1 to C4 alkyl group.

[0156] In the description of formula (3), the alkyl part and alkylene part of alkyl, alkenyl, acyl, hydroxyalkyl, methoxyalkyl, alkoxy, and phenylalkyl can be either unbranched or branched.

[0157] R in equation (3) 1 R 2 R 1 'and R 2 The preferred example of ' is the same as R described in the explanation of equation (1) above. 1 and R 2 The preferred example is the same. The preferred example of X' in equation (3) is the same as the preferred example of X described in the explanation of equation (1) above. A can be -CYR 3 - Y can be a hydrogen atom. R 3 It can be a hydrogen atom. It can be A with -CYR. 3 - and Y and R 3 All of them are hydrogen atoms. In other words, A can be -CH2-.

[0158] R in equation (3) 1 R 2 R 1 '、R 2 ', X, X', and A can be used in any combination of the above preferred examples.

[0159] The photopolymerization initiator can be a compound represented by formula (4). The compound of formula (4) is one of the compounds of formula (3).

[0160] [Chemical Formula 6]

[0161]

[0162] Specific examples of photopolymerization initiators are shown in the following formulas (5) to (9). The photopolymerization initiator can be a compound selected from at least one chemical formula of formulas (5) to (9), a compound selected from at least one chemical formula of formulas (5) to (8), a compound selected from at least one chemical formula of formulas (5) to (7), or a compound represented by formula (5). It should be noted that the compound of formula (8) is derived from a vinyl compound having a chemical structure X in its side chain. More specifically, it is an oligomer of this vinyl compound.

[0163] [Chemical Formula 7]

[0164]

[0165] [Chemical Formula 8]

[0166]

[0167] [Chemical Formula 9]

[0168]

[0169] [Chemical Formula 10]

[0170]

[0171] [Chemical Formula 11]

[0172]

[0173] The photopolymerization initiators shown in formulas (5) to (9) are commercially available as Omnirad 127, Esacure KIP 160, Esacureone, Esacure KIP 150, and Omnirad 1173 (all manufactured by IGM Resins). The photopolymerization initiator can be selected from at least one of them.

[0174] Specific examples of photopolymerization initiators include 1-hydroxycyclohexylphenyl ketone, bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, 2-hydroxy-1-(4-(4-(2-hydroxy-2-methylpropanoyl)benzyl)phenyl)2-methylpropane-1-one, and 2,2-dimethoxy-2-phenylacetophenone. These photopolymerization initiators are commercially available as Omnirad 184, Omnirad 819, Omnirad 127, and Omnirad 651, respectively (all manufactured by IGM Resin).

[0175] The amount of photopolymerization initiator in the adhesive composition, relative to 100 parts by weight of the monomer group and its polymer, is, for example, 20 parts by weight or less, and can be 10 parts by weight or less, 5.0 parts by weight or less, 3.0 parts by weight or less, 1.0 part by weight or less, 0.5 parts by weight or less, 0.3 parts by weight or less, 0.25 parts by weight or less, 0.2 parts by weight or less, 0.15 parts by weight or less, or even 0.1 parts by weight or less, and further, 0.05 parts by weight or less. The lower limit of the amount relative to 100 parts by weight of the monomer group and its polymer is, for example, 0.01 parts by weight or more, and can be 0.03 parts by weight or more.

[0176] The adhesive composition may contain a crosslinking agent. Examples of crosslinking agents are polyfunctional monomers having two or more polymerizable functional groups per molecule. The polyfunctional monomer may be a (meth)acrylic acid monomer. Examples of polyfunctional monomers include monomers having two or more C=C bonds per molecule, and monomers having one or more C=C bonds and one or more polymerizable functional groups such as epoxy, aziridinyl, α-azolinyl, hydrazyl, or hydroxymethyl per molecule. Preferably, the polyfunctional monomer has two or more C=C bonds per molecule.

[0177] Examples of multifunctional monomers include: polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol diacrylate (NDDA), 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tri(meth)acrylate, and other multifunctional acrylates (ester compounds formed by polyols and (meth)acrylic acid, etc.); allyl methacrylate, vinyl methacrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di(meth)acrylate, and hexyl di(meth)acrylate. The multifunctional monomer is preferably a multifunctional acrylate, more preferably 1,9-nonanediol diacrylate, trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, or dipentaerythritol hexa(meth)acrylate.

[0178] The crosslinking agent may include other crosslinking agents besides the aforementioned multifunctional monomers. Isocyanate crosslinking agents are examples of other crosslinking agents. The adhesive composition may include an isocyanate crosslinking agent as a crosslinking agent, or it may include both the aforementioned multifunctional monomers and isocyanate crosslinking agents as crosslinking agents. Isocyanate crosslinking agents can help improve the anchoring force between the adhesive sheet 1 and the optical film.

[0179] As isocyanate crosslinking agents, compounds having at least two isocyanate groups (isocyanate compounds) can be used. The number of isocyanate groups in the isocyanate compound is preferably three or more. There is no particular upper limit to the number of isocyanate groups, for example, five. Examples of isocyanate compounds include aromatic isocyanate compounds, alicyclic isocyanate compounds, and aliphatic isocyanate compounds.

[0180] Examples of aromatic isocyanate compounds include: phenyl diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, phenyl dimethyl diisocyanate, etc.

[0181] Examples of alicyclic isocyanate compounds include: 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated phenyl diisocyanate, hydrogenated toluene diisocyanate, and hydrogenated tetramethylphenyl diisocyanate.

[0182] Examples of aliphatic isocyanate compounds include: trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate (HDI), pentamethylene diisocyanate (PDI), 1,2-propylidene diisocyanate, 1,3-butylidene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0183] Examples of isocyanate crosslinking agents include polymers (dimers, trimers, pentamers, etc.) of the aforementioned isocyanate compounds, adducts obtained by addition reactions with polyols such as trimethylolpropane, urea-modified compounds, biuret-modified compounds, urethane-modified compounds, isocyanurate-modified compounds, carbodiimide-modified compounds, and urethane prepolymers obtained by addition reactions with polyether polyols, polyester polyols, acrylic polyols, polybutadiene polyols, polyisoprene polyols, etc.

[0184] The isocyanate crosslinking agent preferably comprises an aliphatic isocyanate compound and / or a derivative thereof. Particularly preferred are at least one selected from pentamethylene diisocyanate (PDI) crosslinking agents (PDI and its derivatives) and hexamethylene diisocyanate (HDI) crosslinking agents (HDI and its derivatives). Specific examples of PDI crosslinking agents include isocyanurate modified PDI. Specific examples of HDI crosslinking agents include isocyanurate modified HDI, biuret modified HDI, etc.

[0185] The amount of crosslinking agent in the adhesive composition varies depending on the molecular weight, number of functional groups, etc., and is, for example, 5 parts by weight or less relative to 100 parts by weight of the monomer group and its polymer, and can be 3 parts by weight or less, 2 parts by weight or less, 1 part by weight or less, and further can be 0.5 parts by weight or less. The lower the amount of crosslinking agent in the adhesive composition, the greater the tendency for the creep of the adhesive sheet 1 to increase. The lower limit of the amount is, for example, 0.01 parts by weight or more, and can be 0.05 parts by weight or more, and further can be 0.1 parts by weight or more.

[0186] It should be noted that when the adhesive composition contains an isocyanate crosslinking agent, the amount of the isocyanate crosslinking agent relative to 100 parts by weight of the monomer group and its polymer is, for example, 0.02 parts by weight or more, and can be 0.05 parts by weight or more, 0.1 parts by weight or more, 0.5 parts by weight or more, and further, 1 part by weight or more. When the adhesive composition contains an isocyanate crosslinking agent, if the amount of the hydroxyl-containing monomer in the adhesive composition is adjusted to a small value, there is a tendency for the anchoring force between the adhesive sheet 1 and the optical film to be further improved.

[0187] When isocyanate crosslinking agents are added, especially in high-temperature environments, the adhesive sheet can sometimes harden. In such cases, the stress relaxation properties of the adhesive sheet are impaired, and therefore, the expansion and contraction stresses of the optical film are easily transmitted to the interface between the adhesive sheet and the substrate, leading to a tendency for peeling. To ensure the anchoring force between the adhesive sheet and the optical film through methods other than adding isocyanate crosslinking agents, it is desirable that the adhesive composition does not contain isocyanate crosslinking agents.

[0188] The adhesive composition may further include a rework improver. A rework improver is a component that, when the adhesive sheet 1 is bonded to an adherend such as alkali-free glass or a transparent conductive layer, reduces the adhesion strength (e.g., adhesion strength P0 described later) between the adhesive sheet 1 and the adherend by segregation on the surface of the adherend.

[0189] Reprocessing improvers can be, for example, silane coupling agents containing alkoxysilyl groups, preferably having both alkoxysilyl groups and polar groups. Specific examples of alkoxy groups contained in the alkoxysilyl group in reprocessing improvers include methoxy, ethoxy, etc. Examples of polar groups include carboxyl groups, acid anhydride groups, epoxy groups, etc. The carboxyl group can be a group generated by hydrolyzing an acid anhydride group. Examples of acid anhydride groups include succinic anhydride groups, phthalic anhydride groups, maleic anhydride groups, etc. Reprocessing improvers can have ether groups other than epoxy groups, or they can have a polyether backbone.

[0190] The reprocessing improver preferably has at least one selected from anhydride groups and epoxy groups. When a reprocessing improver having anhydride groups and epoxy groups is used, there is a tendency to increase the adhesion strength (adhesion strength P1 described later) between the adhesive sheet 1 and the glass by heat treatment after the adhesive sheet 1 is bonded to alkali-free glass.

[0191] Examples of reprocessing improvers include alkoxysilane compounds with polar groups, organopolysiloxane compounds with polar groups and alkoxysilyl groups, and polyether compounds with alkoxysilyl groups.

[0192] Examples of alkoxysilane compounds with polar groups include: 2-trimethoxysilylethyl succinic anhydride, 3-trimethoxysilylpropyl succinic anhydride (manufactured by Shin-Etsu Chemical Industry Co., Ltd., trade name "X-12-967C"), 3-triethoxysilylpropyl succinic anhydride, 3-methyldiethoxysilylpropyl succinic anhydride, and 1-carboxy-3-triethoxysilylpropyl succinic anhydride.

[0193] Examples of organopolysiloxane compounds containing polar groups and alkoxysilyl groups include oligomeric silane coupling agents containing anhydride groups (trade name "X-24-9591F") and oligomeric silane coupling agents containing epoxy groups (trade names "X-41-1053", "X-41-1059A", "X-41-1056", "X-40-2651", etc.) manufactured by Shin-Etsu Chemical Co., Ltd.

[0194] Examples of polyether compounds containing alkoxysilyl groups include MS Polymer S203, S303, S810, SILYL EST250, EST280, SAT10, SAT200, SAT220, SAT350, SAT400 manufactured by Kaneka Corporation, and EXCESTAR S2410, S2420, S3430 manufactured by Asahi Glass Co., Ltd.

[0195] The amount of the reprocessing improver in the adhesive composition relative to 100 parts by weight of the monomer group and its polymer is, for example, 0.01 parts by weight or more, and can be 0.05 parts by weight or more, 0.1 parts by weight or more, 0.2 parts by weight or more, 0.5 parts by weight or more, and further can be 0.6 parts by weight or more. The upper limit of the amount is, for example, 10 parts by weight or less, and can be 5 parts by weight or less, and further can be 1 part by weight or less. The adhesive composition may not contain the reprocessing improver.

[0196] The adhesive composition may also contain additives other than those described above. Examples of additives include chain transfer agents, silane coupling agents other than reprocessing improvers, viscosity modifiers, tackifiers, plasticizers, softeners, anti-aging agents, fillers, colorants, antioxidants, surfactants, antistatic agents, and UV absorbers.

[0197] The solvent content in the adhesive composition is, for example, 5% by weight or less, and can be 4% by weight or less, 3% by weight or less, 2% by weight or less, 1% by weight or less, and further, 0.5% by weight or less. The adhesive composition may substantially not contain solvent. Substantially not containing solvent means that it is permissible to include solvents from additives or the like at a content of, for example, 0.1% by weight or less, preferably 0.05% by weight or less, more preferably 0.01% by weight or less.

[0198] The viscosity of the adhesive composition is preferably 5 to 150 poise. Adhesive compositions with viscosities within the above range are particularly suitable for forming the coating layer described later.

[0199] (Physical properties of adhesive sheets)

[0200] The polymerization rate of the monomer group in adhesive sheet 1 is preferably 90% or higher. The polymerization rate can be 95% or higher, 98% or higher, and further 99% or higher.

[0201] The gel fraction of adhesive sheet 1 is, for example, 50% or more, 75% or more, 80% or more, and even 85% or more.

[0202] (Manufacturing method of adhesive sheet)

[0203] The manufacturing method of adhesive sheet 1 is not particularly limited. As an example, when the adhesive composition is light-curable, adhesive sheet 1 can be manufactured by the following method. First, as... Figure 5A , Figure 5B As shown, a first laminate 15 is fabricated, comprising a substrate sheet 21, a coating layer 22 containing an adhesive composition, and a release liner 23. A cured sheet 20 is formed from the coating layer 22 by irradiating the first laminate 15 with light 14. Figure 5C The release liner 23 is peeled off from the cured sheet 20, and the exposed surface of the cured sheet 20 is subjected to surface modification treatment. Surface modification treatment can be performed, for example, by irradiating the exposed surface of the cured sheet 20 with active energy rays 13. Figure 5D Through surface modification treatment, an adhesive sheet 1 is formed from the cured sheet 20. Figure 5E In detail, a second layer 6 with a high elastic modulus can be formed in the surface-modified portion, while a first layer 5 can be formed as the other portion.

[0204] Typically, the irradiation of the first laminate 15 by light 14 can be performed from one side of the substrate sheet 21. Figure 5A At this point, light 14 passes through the substrate sheet 21 and reaches the coating layer 22, causing the coating layer 22 to cure. However, it should be noted that the irradiation of light 14 can be performed from one side of the release liner 23, or from both sides of the release liner 23 and the substrate sheet 21. Figure 5B The cured sheet 20 formed by the coating layer 22 is held between the substrate sheet 21 and the release liner 23 to form part of the second laminate 16 until the release liner 23 is peeled off.

[0205] Light 14 is, for example, visible light or ultraviolet light with a wavelength shorter than 450 nm. Light 14 may contain light with a wavelength in the same region as the absorption wavelength of the photopolymerization initiator contained in the adhesive composition. Light obtained by blocking short-wavelength light with a wavelength below 300 nm through a filter or the like can be irradiated, and blocking the short-wavelength light is suitable for suppressing the deterioration of the substrate sheet 21 and / or release liner 23 caused by light 14. The light source of light 14 is, for example, a lighting device equipped with an ultraviolet irradiation lamp. Examples of ultraviolet irradiation lamps are light-emitting diodes (LEDs), low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, metal halide lamps, xenon lamps, microwave-excited mercury lamps, black lights, chemical lamps, germicidal lamps, low-pressure discharge mercury lamps, and excimer lasers. Two or more ultraviolet irradiation lamps may also be combined. According to LEDs, the bandwidth of the irradiated ultraviolet light can be narrowed compared to using other light sources.

[0206] The light source for light 14 can be an LED emitting light with a peak wavelength of 300-450 nm, or an LED emitting light with a peak wavelength of 340 ± 10 nm (hereinafter referred to as LED340). According to the researchers of the present invention, the use of LED340, compared to, for example, using a black light source, has the potential to contribute to at least one of increasing the polymerization rate of the monomers selected from the adhesive sheet 1 (specifically, the curing sheet 20), increasing the molecular weight of the polymer, and reducing the residual amount of photopolymerization initiator. Furthermore, according to LED340, compared to using an LED emitting light with a peak wavelength of approximately 365 nm, there is a tendency to suppress heat generation. Suppressing heat generation helps control the temperature of the coating layer 22. It should be noted that the peak wavelength refers to the wavelength at which the intensity reaches its maximum value in a spectrum showing the relationship between the wavelength and intensity of light.

[0207] The illuminance of light 14 illuminating the first layer 15 (specifically, coating layer 22) is, for example, 2.0~30 mW / cm². 2 The illuminance can be 2.5 mW / cm². 2 Above, 3.0mW / cm 2 Above, 3.5mW / cm 2 Above, 4.0mW / cm 2 Above, 5.0mW / cm 2 Above, 6.0mW / cm 2 Above, 7.0mW / cm 2 Above, 8.0mW / cm 2 Above, 9.0mW / cm 2 The above can further be expressed as 10mW / cm 2 The above. The upper limit for illuminance is, for example, 25 mW / cm². 2The following can be 20mW / cm 2 Therefore, it can be further reduced to 15mW / cm 2 the following.

[0208] The duration of illumination of the first laminate 15 (specifically, the coating layer 22) with light 14 is, for example, from 10 seconds to 1000 seconds, and can be 60 seconds or more, 100 seconds or more, 150 seconds or more, 200 seconds or more, 250 seconds or more, and further, 300 seconds or more. The upper limit of the duration is, for example, less than 800 seconds, and can be less than 600 seconds, 500 seconds or less, 400 seconds or less, 350 seconds or less, 300 seconds or less, and further, less than 250 seconds. The illumination with light 14 can be continuous or intermittent.

[0209] The cumulative light intensity of light 14 for the first layer stack 15 (specifically, coating layer 22) is, for example, 25 mJ / cm. 2 The above can be 100mJ / cm 2 Above, 250mJ / cm 2 Above, 500mJ / cm 2 Above, 750mJ / cm 2 Above, 850mJ / cm 2 Above, 1000mJ / cm 2 Above, 1250mJ / cm 2 The above can be further expressed as 1500 mJ / cm 2 That's all. There is no specific upper limit for the cumulative light intensity, for example, 5000 mJ / cm². 2 Below that, it can be 4000mJ / cm 2 Below, 3000mJ / cm 2 Below, 2500mJ / cm 2 Below, 2000mJ / cm 2 The following can be further expressed as 1750 mJ / cm 2 the following.

[0210] An example of the substrate (hereinafter "substrate") to which the liner 23 is peeled off is a resin film. Examples of resins that may be included in the substrate include polyesters such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyethersulfone, polycarbonate, polyamide, polyimide, polyolefin, (meth)acrylic resin, polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl alcohol, polyarylate, and polyphenylene sulfide. The resin is preferably a polyester such as polyethylene terephthalate.

[0211] The release liner 23 may have light 14 transmittance, or it may have the same degree of light 14 transmittance as the substrate sheet 21.

[0212] The thickness of the peeling liner 23 is, for example, 10~200μm, or 25~150μm.

[0213] The release liner 23 may have layers other than the substrate. The release liner 23 may have a release layer. For example, the release liner 23 may have a substrate and a release layer formed on one side of the substrate. The release liner 23 may be used such that the release layer is on the side of the coating layer 22.

[0214] Typically, the release layer is a cured layer of a release agent composition containing a release agent. Various release agents can be used, such as silicone-based release agents, fluorinated release agents, long-chain alkyl-based release agents, fatty acid amide-based release agents, and silica powder. The release liner 23 may have a cured layer (hereinafter, "silicone release layer") of a release agent composition containing a silicone-based release agent as the main component. The silicone release layer is particularly suitable for balancing adhesion and peelability relative to the adhesive sheet 1. It should be noted that, in this specification, the main component refers to the component with the highest content.

[0215] Organosilicon release agents include various curing types of organosilicon materials, such as addition reaction type, condensation reaction type, UV curing type, electron beam curing type, and solvent-free type, with addition reaction curing type organosilicon materials being preferred. Addition reaction curing type organosilicon materials are particularly suitable for forming a release layer that balances adhesion and peelability relative to the adhesive sheet 1. The curing type organosilicon material can be an organosilicon-modified resin obtained by introducing reactive organosilicon into organic resins such as urethane, epoxy, and alkyd resins through graft polymerization or the like.

[0216] Examples of addition-reaction-curable silicone materials are polyorganosiloxanes containing vinyl or alkenyl groups within the molecule. Addition-reaction-curable silicone materials may also lack hydrogenated silyl groups. Examples of alkenyl groups include 3-butenyl, 4-pentenyl, 5-hexenyl, 6-heptenyl, 7-octenyl, 8-nonenyl, 9-decenyl, 10-undecenyl, and 11-dodecenyl. Examples of polyorganosiloxanes include polyalkylalkylsiloxanes such as polydimethylsiloxane, polydiethylsiloxane, and polymethylethylsiloxane, polyalkylarylsiloxanes, and copolymers of various Si-containing monomers such as poly(dimethylsiloxane-diethylsiloxane). Polyorganosiloxanes are preferably polydimethylsiloxane.

[0217] Release agent compositions containing silicone-based release agents as the main component (hereinafter, "silicone release agent compositions") typically contain crosslinking agents. Examples of crosslinking agents are polyorganosiloxanes having hydrogenated silyl groups. Crosslinking agents may have two or more hydrogenated silyl groups in one molecule.

[0218] Organosilicon release agent compositions may also contain curing catalysts. Examples of curing catalysts are platinum-based catalysts. Examples of platinum-based catalysts include chloroplatinic acid, platinum olefin complexes, and chloroplatinic acid olefin complexes. The amount of platinum-based catalyst used relative to the total solids content of the composition is, for example, 10 to 1000 ppm (by weight, converted to platinum).

[0219] Silicone release agent compositions may also contain additives. Examples of additives include peel control agents and adhesion improvers. Examples of peel control agents are unreactive silicone resins, more specifically, organosiloxanes such as octamethylcyclotetrasiloxane and MQ resins. The amount of peel control agents and adhesion improvers, in total, is, for example, 1 to 30% by weight relative to the total solids content of the composition. Other examples of additives include fillers, antistatic agents, antioxidants, UV absorbers, plasticizers, and colorants. The amount of other additives, in total, is, for example, less than 10% by weight relative to the total solids content of the composition.

[0220] The silicone release agent composition may also contain organic solvents. Examples of organic solvents include hydrocarbon solvents such as cyclohexane, n-hexane, and n-heptane; aromatic solvents such as toluene and xylene; ester solvents such as ethyl acetate and methyl acetate; ketone solvents such as acetone and methyl ethyl ketone; and alcohol solvents such as methanol, ethanol, and butanol. Two or more organic solvents may also be included. The preferred amount of organic solvent is 80-99.9% by weight of the silicone release agent composition.

[0221] A release layer can be formed, for example, by heating and drying a coating film containing a release agent composition formed on a substrate. The release agent composition can be applied using various methods such as roller coating, licking coating, gravure coating, reverse coating, brush coating, spraying, dip roller coating, bar coating, doctor blade coating, air knife coating, curtain coating, die lip coating, and die coating. Heating and drying can be performed using hot air drying, for example. The heating temperature and time vary depending on the heat resistance of the substrate, typically ranging from 80 to 150°C for approximately 10 seconds to 10 minutes. If necessary, irradiation with active energy rays such as ultraviolet light can also be used in combination.

[0222] The thickness of the release layer is, for example, 10~300nm. The upper limit of the thickness can be below 200nm, below 150nm, below 120nm, below 110nm, below 100nm, less than 100nm, below 90nm, below 80nm, below 70nm, less than 70nm, and further below 65nm. The lower limit of the thickness can be above 15nm, above 20nm, above 25nm, above 30nm, above 35nm, above 40nm, above 45nm, and further above 50nm.

[0223] The peeling liner 23 can be in the form of a single sheet or in the form of a strip.

[0224] An example of substrate sheet 21 is a resin film. An example of the resin contained in substrate sheet 21 is the same as an example of the resin that may be contained in a liner substrate.

[0225] The preferred substrate sheet 21 has excellent transmittance to light 14.

[0226] The thickness of the substrate sheet 21 is, for example, 10~200μm, or 25~150μm.

[0227] The substrate sheet 21 may have a release layer on one side of the coating layer 22. Examples of release layers that the substrate sheet 21 may have and their manufacturing methods are the same as examples of release layers that the release liner 23 may have and their manufacturing methods. Release layers may also be present on both the release liner 23 and the substrate sheet 21. In this case, the release layers of both may be formed from a release agent composition containing the same release agent as a main component. Furthermore, the thicknesses of the release layers of the two may differ; for example, the release layer of the substrate sheet 21 may be thicker.

[0228] The substrate sheet 21 can typically be selected as a sheet with greater peel force than the cured sheet 20 compared to the release liner 23.

[0229] The substrate sheet 21 can be a single sheet or a strip.

[0230] The first laminate 15 can be formed, for example, by forming a coating layer 22 on a substrate sheet 21 (or release liner 23) and placing the release liner 23 (or substrate sheet 21) on the formed coating layer 22. Alternatively, the first laminate 15 can be formed by coating in such a way that an adhesive composition flows into a space between substrate sheets 21 and release liner 23 held at a given interval with their main surfaces facing each other.

[0231] The coating layer 22 can be formed by various coating methods such as roller coating, roller licking coating, gravure coating, reverse coating, roller brushing, spraying, dip roller coating, bar coating, scraping coating, air knife coating, curtain coating, die lip coating, and die coating.

[0232] The thickness of the coating layer 22 can be adjusted according to the thickness of the target adhesive sheet 1, for example, 5~500μm, 5~250μm, 5~150μm, 5~100μm, 5~50μm, 5~30μm, 5~25μm, and further, 5~20μm.

[0233] Examples of surface modification treatments performed on the cured sheet 20 include corona treatment, plasma treatment, excimer laser treatment, and flame treatment, with corona treatment being preferred. In other words, the active energy beam 13 can be at least one selected from electron beams, ion beams, plasma beams, and ultraviolet light. Each surface modification treatment can be performed using a corresponding known processing apparatus. The conditions for the surface modification treatment are as described above.

[0234] [Implementation of Optical Laminations]

[0235] An example of the optical laminate of this embodiment is shown below. Figure 6 . Figure 6 The optical laminate 10 includes the aforementioned adhesive sheet 1 and at least one optical film 2 selected from polarizing films and retardation films. The adhesive sheet 1 is preferably directly bonded to the optical film 2. Figure 6 In the example, the first surface 1a of the adhesive sheet 1 is in contact with the optical film 2. The optical laminate 10 may have a structure in which a substrate sheet used in the fabrication of the adhesive sheet 1 is laminated to the adhesive sheet 1. The optical laminate 10 may be used as an optical film with an adhesive sheet.

[0236] (Optical film)

[0237] The optical film 2 has a surface 2a opposite to the adhesive sheet 1. For example, surface 2a is in contact with the first surface 1a of the adhesive sheet 1. Surface 2a of the optical film 2 is subjected to a surface modification treatment. Based on the surface 2a to which the surface modification treatment is applied, there is a tendency to improve the anchoring force between the adhesive sheet 1 and the optical film 2. As a surface modification treatment, the surface modification treatment described above for the adhesive sheet 1 can be cited as an example.

[0238] Surface 2a is preferably subjected to corona treatment as a surface modification treatment. When applying corona treatment to surface 2a, conditions such as the discharge amount can be appropriately adjusted, for example, within the range described above for adhesive sheet 1.

[0239] As described above, the optical film 2 comprises at least one selected from polarizing films and retardation films. The optical film 2 can be a laminated film comprising a polarizing film and / or a retardation film. The optical film 2 can comprise a glass film. However, the optical film 2 is not limited to the examples described above.

[0240] A polarizing film includes a polarizer. Typically, a polarizing film includes a polarizer and a protective film (a transparent protective film). The protective film is disposed in contact with the ground, for example, the main surface (the surface with the widest area) of the polarizer. The polarizer may be disposed between two protective films. The protective film may be disposed on at least one side of the polarizer.

[0241] There are no particular limitations on what constitutes a polarizer. Examples include: polarizers obtained by uniaxially stretching hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene-vinyl acetate copolymer films, after adsorbing dichroic substances such as iodine and dichroic dyes onto them; and polyene-oriented films such as dehydrated polyvinyl alcohol products and dehydrochlorinated polyvinyl chloride products. Typically, a polarizer is formed from a polyvinyl alcohol film (which may contain partially saponified ethylene-vinyl acetate copolymer films) and dichroic substances such as iodine.

[0242] The thickness of the polarizer is not particularly limited; for example, it can be less than 80 μm, less than 50 μm, less than 30 μm, less than 25 μm, and even less than 20 μm. The lower limit of the polarizer's thickness is not particularly limited; for example, it can be greater than 1 μm, greater than 5 μm, greater than 10 μm, and even greater than 15 μm. Suppressing dimensional variations in thin polarizers (e.g., less than 20 μm thick) can contribute to improving the durability of optical laminates, especially their durability at high temperatures.

[0243] As materials for the protective film, thermoplastic resins with excellent properties such as transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy can be used. Specific examples of such thermoplastic resins include cellulose resins such as cellulose triacetate, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The protective film material can be thermosetting resins or UV-curable resins such as (meth)acrylic acid, urethane, acrylate urethane, epoxy, and silicone. In the case where the polarizing film has two protective films, the materials of the two protective films can be the same or different. For example, a protective film formed of thermoplastic resin can be bonded to one main surface of the polarizer via an adhesive, and a protective film formed of thermosetting resin or UV-curable resin can be bonded to the other main surface of the polarizer. The protective film can contain one or more arbitrary additives. Examples of additives include: ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, and colorants.

[0244] It should be noted that films containing (meth)acrylic resin tend to have weak adhesive strength with adhesive sheets. However, in this embodiment, by appropriately adjusting the creep and elastic modulus G1 of adhesive sheet 1, even when the surface of the protective film containing (meth)acrylic resin corresponds to the surface 2a of the optical film 2, the anchoring force between adhesive sheet 1 and optical film 2 can be adjusted to a sufficiently high value.

[0245] The thickness of the protective film can be appropriately determined. Generally speaking, it is about 10~200μm, considering factors such as strength, processability, operability, and thinness.

[0246] Polarizing lenses and protective films are typically bonded together using water-based adhesives. Examples of water-based adhesives include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, waterborne polyurethane, and waterborne polyester. Other adhesives besides those mentioned above include UV-curable adhesives and electron beam-curable adhesives. Electron beam-curable polarizer adhesives exhibit suitable adhesion to various protective films. The adhesive may also contain metallic compound fillers.

[0247] In polarizing films, a phase retardation film or similar material can be formed on the polarizer to replace the protective film. Alternatively, another protective film or a phase retardation film can be applied to the protective film.

[0248] Regarding the protective film, a hard coating can also be applied to the surface opposite to the surface to which the polarizer is bonded, and it can also be treated for purposes such as anti-reflection, anti-adhesion, diffusion, and anti-glare.

[0249] The polarizing film can be a circularly polarizing film.

[0250] As a retardation film, films obtained by stretching a polymer film or by aligning and immobilizing a liquid crystal material can be used. Retardation films, for example, exhibit birefringence in the in-plane and / or thickness directions.

[0251] Phase retardation films include anti-reflective phase retardation films (see Japanese Patent Application Publication No. 2012-133303

[0221] ,

[0222] ,

[0228] ), viewing angle compensation phase retardation films (see Japanese Patent Application Publication No. 2012-133303

[0225] ,

[0226] ), and tilt-oriented phase retardation films for viewing angle compensation (see Japanese Patent Application Publication No. 2012-133303

[0227] ), etc.

[0252] There are no particular limitations on the specific composition of the retardation film, such as the phase difference value, the configuration angle, the three-dimensional birefringence, whether it is a single layer or a multilayer, and known retardation films can be used.

[0253] The thickness of the phase retardation film is preferably 20 μm or less, more preferably 10 μm or less, even more preferably 1 to 9 μm, and particularly preferably 3 to 8 μm.

[0254] Phase retardation films may include, for example, quarter-wave plates and / or half-wave plates obtained by aligning and immobilizing liquid crystal materials.

[0255] (Properties of optical laminates)

[0256] In this embodiment, there is a tendency for the anchoring force F between the adhesive sheet 1 and the optical film 2 to be large. The anchoring force F is, for example, 10.0 N / 25 mm or more, and can be 11.0 N / 25 mm or more, 12.0 N / 25 mm or more, 13.0 N / 25 mm or more, 14.0 N / 25 mm or more, 15.0 N / 25 mm or more, 16.0 N / 25 mm or more, 17.0 N / 25 mm or more, and further, 18.0 N / 25 mm or more. There is no particular upper limit to the anchoring force F; for example, it can be 50 N / 25 mm or less, or 30 N / 25 mm or less.

[0257] The anchoring force F between the adhesive sheet 1 and the optical film 2 can be measured by the following method. First, a test piece is prepared by cutting the optical laminate 10, which is to be evaluated, into pieces with a width of 25 mm and a length of 150 mm. Next, the entire surface of the optical film 2 on the test piece is stacked with a stainless steel test plate via a double-sided tape, and a 2 kg roller is rolled back and forth once to press them together. Next, the adhesive sheet 1 on the test piece is stacked with an evaluation sheet, and a 2 kg roller is rolled back and forth once to press them together. The evaluation sheet has a width of 30 mm and a length of 150 mm, and is not particularly limited as long as it does not peel off from the adhesive sheet 1 during the test. For example, an ITO film (125 Tetoraito OES (manufactured by Oike Kogyo Co., Ltd.) can be used as the evaluation sheet. Next, using a commercially available tensile testing machine, while holding the evaluation sheet, the adhesive sheet 1 was peeled from the optical film 2 at a peel angle of 180° and a tensile speed of 300 mm / min. The average peel force at this point was determined as the anchoring force F between the adhesive sheet 1 and the optical film 2. It should be noted that the above test was conducted in an atmosphere of 23°C.

[0258] From the viewpoint of reoperability, it is preferable that the adhesive force P0 of the optical laminate 10, as determined by the following test 1, is 8.0 N / 25 mm or less.

[0259] Experiment 1: Adhesive sheet 1 was adhered to alkali-free glass, and then peeled off from the alkali-free glass at a peeling speed of 300 mm / min and a peeling angle of 90°. The force required at this time (adhesive force P0) was measured.

[0260] Experiment 1 was conducted as follows. First, a test piece was prepared by cutting a strip of optical laminate 10 into a length of 150 mm × width of 25 mm. Next, the test piece was adhered to alkali-free glass via adhesive sheet 1. Alkali-free glass is glass that substantially does not contain alkali components (alkali metal oxides), specifically, the weight ratio of alkali components in the glass is, for example, 1000 ppm or less, and further, 500 ppm or less. Alkali-free glass is, for example, in sheet form and has a thickness of 0.5 mm or more.

[0261] The bonding of the test piece to the alkali-free glass was carried out, for example, using a laminator, in a manner that prevented air bubbles from being incorporated between the alkali-free glass and the adhesive sheet 1. After bonding, the test piece was placed in an autoclave at 50°C and 5 atmospheres (absolute pressure) for 15 minutes to homogenize the bond between the alkali-free glass and the adhesive sheet 1, ensuring a tight seal between the adhesive sheet 1 and the alkali-free glass. Next, the test piece was peeled from the alkali-free glass at a peel speed of 300 mm / min and a peel angle of 90° (measurement length 80 mm). At this time, the force required to peel the test piece from the alkali-free glass was measured at intervals of 0.5 s. The average value of the measured values ​​was determined as the adhesive force P0.

[0262] The adhesive strength P0 is preferably 7.0 N / 25 mm or less, but can be 6.0 N / 25 mm or less, 5.0 N / 25 mm or less, 4.5 N / 25 mm or less, 4.0 N / 25 mm or less, and further can be 3.5 N / 25 mm or less. The lower limit of the adhesive strength P0 is, for example, 0.5 N / 25 mm or more, 1.0 N / 25 mm or more, and further can be 1.5 N / 25 mm or more. The adhesive strength P0 is preferably 0.5 to 7.0 N / 25 mm.

[0263] The difference (F-P0) between the anchoring force F and the adhesive force P0 is preferably 5.0 N / 25 mm or more, and can be 6.0 N / 25 mm or more, 7.0 N / 25 mm or more, 8.0 N / 25 mm or more, 9.0 N / 25 mm or more, 10.0 N / 25 mm or more, 11.0 N / 25 mm or more, 12.0 N / 25 mm or more, and further can be 13.0 N / 25 mm or more. The upper limit of the difference (F-P0) is, for example, 20 N / 25 mm or less.

[0264] Furthermore, regarding the adhesive sheet 1 of the optical laminate 10, from a durability point of view, it is preferable that the adhesion is improved when it has undergone heat treatment while in contact with alkali-free glass. As an example, it is preferable that the adhesive force P1 of the optical laminate 10, as determined by the following test 2, is 8.0 N / 25 mm or more.

[0265] Experiment 2: Adhesive sheet 1 was adhered to alkali-free glass and subjected to a heat treatment at 60°C for 100 hours. Adhesive sheet 1 was then peeled off from the alkali-free glass at a peeling speed of 300 mm / min and a peeling angle of 90°. The force required at this point (adhesive force P1) was measured.

[0266] In Experiment 2, after homogenizing the bonding between the alkali-free glass and the adhesive sheet 1 in an autoclave, the test piece was subjected to a heat treatment at 60°C for 100 hours under atmospheric pressure. After further reducing the temperature of the test piece to room temperature (e.g., 23°C), the test piece was peeled off from the alkali-free glass. Otherwise, the same method as in Experiment 1 can be used.

[0267] The adhesive strength P1 is preferably 9.0 N / 25 mm or more, and can be 9.5 N / 25 mm or more, 10.0 N / 25 mm or more, and even 10.5 N / 25 mm or more. The upper limit of the adhesive strength P1 is, for example, 20 N / 25 mm or less.

[0268] Another example of the optical laminate of this embodiment is shown below. Figure 7 . Figure 7 The optical laminate 11 has a laminated structure in which an adhesive sheet 1, an optical film 2A, an adhesive sheet 7, and an optical film 2B are sequentially stacked. The optical laminate 11 may have a structure in which a substrate sheet used in the manufacture of the adhesive sheet 1 is laminated onto the adhesive sheet 1.

[0269] In the optical laminate 11, typically, optical film 2A is a retardation film and optical film 2B is a polarizing film. Adhesive sheet 7 functions as an interlayer adhesive for optical films 2A and 2B. Adhesive sheet 7 can use known adhesives or the adhesive described above for adhesive sheet 1.

[0270] The optical laminates 10 and 11 of this embodiment can be distributed and stored, for example, in the form of a wound body formed by winding a strip of optical laminate, or in the form of a single sheet of optical laminate.

[0271] Typically, the optical laminate of this embodiment can be used in an image display device. The image display device, for example, includes optical laminate 10 or 11, which can be formed by bonding optical laminate 10 or 11 to an image display panel. Bonding is performed, for example, by adhesive sheet 1. The image display device can be an organic EL display or a liquid crystal display. However, the image display device is not limited to the examples described above. The image display device can also be an electroluminescent (EL) display, a plasma display (PD), a field emission display (FED), etc. The image display device can be used for home appliances, automotive applications, public information displays (PIDs), etc.

[0272] Example

[0273] The present invention will now be described in more detail through embodiments. The present invention is not limited to the embodiments shown below.

[0274] [Single Slurry A1]

[0275] 95.5 parts by weight of n-butyl acrylate (BA), 4.4 parts by weight of acrylic acid (AA), 0.1 parts by weight of 4-hydroxybutyl acrylate (HBA), 0.05 parts by weight of 1-hydroxycyclohexylphenyl ketone (Omnirad 184, manufactured by IGM Resins B.V.) as a photopolymerization initiator, and 0.05 parts by weight of 2,2-dimethoxy-2-phenylacetophenone (Omnirad 651, manufactured by IGM Resins BV.) were added to a four-necked flask and irradiated with ultraviolet light in a nitrogen atmosphere, thereby obtaining a monomer slurry A1 after partial photopolymerization. The ultraviolet irradiation continued until the viscosity of the liquid in the flask (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30°C) reached approximately 20 Pa·s.

[0276] [Single Slurry A2]

[0277] The monomers and photopolymerization initiators were modified as shown in Table 1. Otherwise, monomer slurry A2 was prepared using the same method as monomer slurry A1.

[0278]

[0279] The abbreviations in Table 1 are as follows.

[0280] BA: n-Butyl acrylate

[0281] AA: Acrylic acid

[0282] HBA: 4-Hydroxybutyl acrylate

[0283] Omnirad 184: 1-Hydroxycyclohexylphenyl ketone (Omnirad 184, manufactured by IGM Resins BV)

[0284] Omnirad 651: 2,2-Dimethoxy-2-phenylacetophenone (Omnirad 651, manufactured by IGM Resins BV)

[0285] Omnirad 819: Bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide (Omnirad 819, manufactured by IGM Resins B.V.)

[0286] [Adhesive compositions C1~C8]

[0287] Next, the monomer slurry, monomer, crosslinking agent, and silane coupling agent were mixed in such a manner as shown in Table 2 below to obtain adhesive compositions C1 to C8.

[0288]

[0289] The abbreviations in Table 2 are as follows.

[0290] NVP: N-vinyl-2-pyrrolidone

[0291] NDDA: 1,9-Nonadiol diacrylate

[0292] KBM403: 3-Epoxypropoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Industry, trade name "KBM-403")

[0293] The final composition of the monomers contained in each adhesive composition is shown in Table 3 below.

[0294]

[0295] (Example 1)

[0296] [Making of the peelable liner]

[0297] A silicone-based release agent composition was prepared by mixing 30 parts by weight of an addition-reaction curable silicone (containing LTC761 with hexenyl polysiloxane, 30% toluene solution, manufactured by Toray Dow Corning), 0.9 parts by weight of a release control agent (containing unreactive silicone resin BY24-850, manufactured by Toray Dow Corning), 2 parts by weight of a curing catalyst (containing platinum catalyst SRX212, manufactured by Toray Dow Corning), and a toluene / hexane mixed solvent (volume ratio 1:1) as a diluent. The concentration of the silicone solid component in the release agent composition was 1.0% by weight. Next, the release agent composition was coated onto one side of a substrate (Lumirror XD500P polyester film, 75 μm thick) using a wire rod, and heated at 130°C for 1 minute to produce a release liner with a release layer (60 nm thick) on one side.

[0298] [Making the Adhesive Sheet]

[0299] Adhesive composition C1 was applied to one side of a substrate sheet (PET separator, Mitsubishi resin, MRF38) using an applicator, forming a coating layer (20 μm thick). Next, a release liner was placed on the formed coating layer to obtain the first laminate. The release liner was positioned so that the release layer was in contact with the coating layer. Next, light was irradiated from one side of the substrate sheet of the first laminate. A black light source (BL) and an LED irradiating light with a peak wavelength of 340 nm were used as the light source. The irradiation conditions for each light source are described below. It should be noted that the illuminance was measured using an illuminance meter (TOPCON TECHNOHOUSE, UD-T3040T2) at a location near the incident surface of ultraviolet light on the substrate sheet.

[0300] BL: Illuminance 6.2 mW / cm² 2 And the irradiation time of 95 seconds (cumulative light intensity 589 mJ / cm²) 2 )

[0301] LED: Illuminance 3.1mW / cm² 2 And the irradiation time of 90 seconds (cumulative light intensity 279 mJ / cm²) 2 )

[0302] The coating layer was photocured by light irradiation, resulting in a second laminate consisting of a release liner, a cured sheet (20 μm thick), and a substrate sheet. Next, the release liner was peeled off from the second laminate using a discharge rate of 61 W / m. 2 •min performs corona treatment on the exposed surface of the cured sheet. As a result, a layer with a high elastic modulus (second layer) is formed in the corona-treated area, thus obtaining the adhesive sheet of Example 1.

[0303] (Examples 2-10 and Comparative Examples 1-3)

[0304] The adhesive composition used and the amount of discharge for corona treatment were modified as shown in Table 4. Otherwise, adhesive sheets of Examples 2-10 and Comparative Examples 1-3 were obtained by the same method as in Example 1. It should be noted that in Comparative Example 1, no corona treatment was performed, and the cured sheet was regarded as an adhesive sheet.

[0305] [AFM Measurement]

[0306] • Elastic modulus G1 of the first surface and elastic modulus G2 of the second surface

[0307] For the adhesive sheets of the examples and comparative examples, the elastic modulus G1 of the first surface and the elastic modulus G2 of the second surface were measured using AFM according to the method described above. It should be noted that for Examples 1-10 and Comparative Examples 2-3, the surface after corona treatment was considered the first surface; for Comparative Example 1, the surface of the adhesive sheet exposed by peeling the release liner from the second laminate was considered the first surface. An MFP-3D Stand Alone manufactured by ASYLUM RESEARCH was used as the scanning probe microscope.

[0308] • Thickness of the second layer

[0309] In the adhesive sheets of the embodiments, a layer with a high elastic modulus (second layer) was formed in the corona-treated portion. The thickness of this second layer was measured using AFM (Anaerobic Measuring Fluid Dynamics) according to the method described above. As a result, the thickness of the second layer in the adhesive sheets of the embodiments was approximately 100 nm to 150 nm. It should be noted that a test piece for measuring the thickness of the second layer was prepared by cutting the laminate obtained by bonding the adhesive sheet to the support film using an ultrathin slicer. The polarizing film D1, described later, was used as the support film.

[0310] [Creep Variable]

[0311] For the adhesive sheets of the examples and comparative examples, creep was measured using the method described above. The support film 51 was a 50 μm thick PET film. The test plate 53 was a SUS304 plate (30 mm × 75 mm, 2.5 mm thick). The laser displacement meter used was an LK-H057 manufactured by Keyence.

[0312] [Fabrication of Optical Laminates]

[0313] Next, polarizing film D1 was fabricated and combined with the adhesive sheets of the examples and comparative examples to create an optical laminate. Polarizing film D1 was prepared using the following method: First, an 80 μm thick polyvinyl alcohol film was dyed in a 0.3% iodine solution at 30°C for 1 minute between rollers with different speed ratios, and stretched to 3 times its original length. Next, it was immersed in an aqueous solution containing 4% boric acid and 10% potassium iodide at 60°C for 0.5 minutes, and stretched to a total stretch ratio of 6 times. After rinsing by immersion in an aqueous solution containing 1.5% potassium iodide at 30°C for 10 seconds, it was dried at 50°C for 4 minutes, thereby obtaining a polarizer with a thickness of 20 μm. A material obtained by saponifying a cellulose triacetate (TAC) transparent protective film (25 μm thick, manufactured by Fujifilm Corporation) using a polyvinyl alcohol adhesive was bonded to one side of the polarizer. Furthermore, a material obtained by corona-treating a cyclic olefin polymer (COP) transparent protective film (13 μm thick, manufactured by Zeon Corporation, Japan) using a polyvinyl alcohol adhesive is bonded to the other side of the polarizer. Thus, a polarizing film D1 with a structure of a TAC-type transparent protective film / polarizer / COP-type transparent protective film is obtained.

[0314] In Examples 1-10 and Comparative Examples 1-3, the aforementioned polarizing film D1 was disposed on the first surface of the adhesive sheet to fabricate an optical laminate. In this case, the polarizing film D1 was disposed such that the surface of the COP-type transparent protective film side was in contact with the adhesive sheet.

[0315] [Anchoring force]

[0316] For the optical laminate produced by the above method, the anchoring force F between the adhesive sheet and the polarizing film was measured using the same method. The double-sided tape used was "No. 531" manufactured by Nitto Denko Corporation. The stainless steel test plate used was a SUS304 plate (40mm wide x 120mm long). The evaluation sheet used was an ITO film (125 Tetoraito OES, manufactured by Oike Kogyo). The tensile testing machine used was an Autograph SHIMAZU AG-I10KN (manufactured by Shimadzu Corporation).

[0317] [Durability]

[0318] The durability (85°C durability) of the optical laminate prepared by the above method was evaluated using the following method. First, a test piece was prepared by cutting a strip of optical laminate measuring 300mm in length and 220mm in width. Next, the test piece was adhered to the surface of 0.7mm thick alkali-free glass (manufactured by Corning Incorporated, trade name "EG-XG") using an adhesive sheet. At this time, the second surface of the adhesive sheet was brought into contact with the alkali-free glass. The adhesion of the test piece to the alkali-free glass was performed using a laminator. After adhesion, the test piece was placed in an autoclave at 50°C and 0.5MPa for 15 minutes to homogenize the bonding between the alkali-free glass and the adhesive sheet, ensuring a tight bond between the adhesive sheet and the alkali-free glass. Next, the test piece was subjected to a heat treatment at 85°C for 500 hours under atmospheric pressure. The appearance of the adhesive sheet between the polarizing film and the alkali-free glass was observed visually, and peeling and internal cracking (paste cracking) were evaluated according to the following criteria.

[0319] • Stripping

[0320] (Evaluation Criteria)

[0321] A: No stripping has been confirmed.

[0322] B: There is slight peeling at the end, but it does not affect the image display function.

[0323] C: There is obvious stripping that affects the image display function.

[0324] • Paste cracking

[0325] (Evaluation Criteria)

[0326] A: No cracking of the paste has been confirmed.

[0327] B: There is a small amount of paste cracking at the end.

[0328] C: Cracks in the paste exist at the end.

[0329]

[0330] As shown in Table 4, compared to the comparative example, the adhesive sheet of the embodiment with a creep deformation of 10 μm or more and an elastic modulus G1 of 1.0 MPa or more on the first surface showed good peeling performance in the durability test. Based on this result, it can be inferred that the adhesive sheet of the embodiment is suitable for suppressing peeling between components of the image display device in high-temperature environments.

[0331] Industrial applicability

[0332] The adhesive sheet of the present invention can be used, for example, in optical laminates and image display devices.

Claims

1. An adhesive sheet having a first surface and a second surface opposite to each other, The creep deformation of the adhesive sheet, as determined by the following tests, is greater than 10 μm. The elastic modulus of the first surface, as measured using atomic force microscopy, is greater than or equal to 1.0 MPa. Test: For the adhesive sheet bonded to a stainless steel test plate with a joint surface of 10mm in length and 10mm in width, a load of 500gf is applied vertically downward with the test plate fixed, and the creep (offset) of the adhesive sheet relative to the test plate is measured 3600 seconds after the load is applied.

2. The adhesive sheet according to claim 1, having a first layer and a second layer located on the first layer, The first surface is consistent with the surface of the second layer.

3. The adhesive sheet according to claim 2, wherein, The thickness of the second layer is less than 1.0 μm.

4. The adhesive sheet according to claim 1, wherein, The creep variable is below 300 μm.

5. The adhesive sheet according to claim 1, wherein, The elastic modulus of the first surface is less than 10.0 MPa.

6. The adhesive sheet according to claim 1, wherein, The elastic modulus of the second surface, as measured using atomic force microscopy, is less than 1.0 MPa.

7. The adhesive sheet according to claim 1, wherein, The first surface is a surface that has undergone surface modification treatment.

8. The adhesive sheet according to claim 7, wherein, The surface modification treatment is a corona treatment.

9. The adhesive sheet according to claim 1, wherein it is formed of an adhesive composition comprising a monomer group and / or a polymer of said monomer group.

10. The adhesive sheet according to claim 9, wherein, The monomer group contains (meth)acrylic acid monomers.

11. The adhesive sheet according to claim 9, wherein, The adhesive composition is photocurable.

12. The adhesive sheet according to claim 9, wherein, The solvent content in the adhesive composition is less than 5% by weight.

13. The adhesive sheet according to claim 1, wherein the thickness is 50 μm or less.

14. An optical laminate comprising: The adhesive sheet according to any one of claims 1 to 13, and An optical film comprising at least one selected from polarizing films and phase difference films.

15. The optical laminate according to claim 14, wherein, The first surface of the adhesive sheet is in contact with the optical film.

16. The optical laminate according to claim 14, wherein, The anchoring force between the adhesive sheet and the optical film is greater than 10.0 N / 25 mm.

17. An image display device comprising the optical laminate of claim 14.

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