JP2010090344A - Method for manufacturing double-coated adhesive tape, display, and bonded substrate and method of manufacturing display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a double-coated adhesive tape which prevents dents caused by the touch-down of the roller on the adhesive layers from occurring, even when it is a double-coated adhesive tape devoid of a base material, a display, and a bonded substrate and a method for manufacturing the display. <P>SOLUTION: The double-coated adhesive tape is planar and used for bonding substrates. The double-coated adhesive tape has an adhesive layer sandwiched between a first release layer and a second release layer and is devoid of a base material. The second release layer is thicker than the first release layer. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

The present invention relates to a double-sided pressure-sensitive adhesive tape, a display device, a method for manufacturing a bonded substrate, and a method for manufacturing a display device. More specifically, a double-sided pressure-sensitive adhesive tape that can be suitably used for bonding between a display panel used in a display device and a substrate such as a touch panel, a manufacturing method of the bonded substrate, and a substrate bonded by the double-sided pressure-sensitive adhesive tape are provided. The present invention relates to a display device and a method for manufacturing the display device.

In a display device used in a portable device typified by a cellular phone (hereinafter also referred to as a portable device), in order to protect the display element from various impacts, it is provided on the front side (display surface side) of the display element. A front plate such as a protective plate is disposed. In recent years, there are many devices in which a touch panel is arranged as an input means of a portable device.

These members included in the display device usually include a substrate made of a rigid body such as glass, and are bonded to each other with a double-sided adhesive tape or an adhesive resin. In this way, the structure in which the members are bonded together and there is no gap such as an air layer between the members is called an air gapless structure. By adopting an air gapless structure, the reflection and reflection of light can be reduced, and the visibility of the display device can be improved.

As the adhesive resin, an ultraviolet (UV) curable resin is often used. The ultraviolet curable resin is a resin that cures when irradiated with ultraviolet rays. Therefore, when the entire surface is bonded using an ultraviolet curable resin, it is necessary to provide a step of irradiating the ultraviolet curable resin with ultraviolet rays after the members are bonded together to cure the ultraviolet curable resin.

The double-sided pressure-sensitive adhesive tape usually has a configuration in which the pressure-sensitive adhesive layer is sandwiched between a pair of release layers. When the entire surface is bonded using a double-sided adhesive tape, there is no need to provide a curing step such as a step of irradiating ultraviolet rays as in the case of using an ultraviolet curable resin, and the resin leaks from the resin layer. Since there is no contamination, the tact time of the process required for the whole surface adhesion of members can be reduced. If there is contamination, the cleaning work takes time.

As a technique related to a double-sided adhesive tape, Patent Document 1 discloses a display with a touch sensor in which a touch sensor and a display element are adhered to each other using a double-sided adhesive tape in which an adhesive layer is provided on both sides of a transparent base film as a base material. An apparatus is disclosed. Moreover, the double-sided adhesive tape which does not have base materials, such as a transparent base film, is also generally known.
JP 2005-222266 A

Since the double-sided pressure-sensitive adhesive tape of Patent Literature 1 has a reduced transmittance depending on the base material, when the double-sided pressure-sensitive adhesive tape of Patent Literature 1 is used for a bonded substrate for a display device, the display quality of the display device is reduced. There was room for improvement.

On the other hand, according to the double-sided adhesive tape which does not have a base material, the fall of the transmittance | permeability can be suppressed compared with the case where the double-sided adhesive tape of patent document 1 is used.

Usually, the manufacturing process of a bonded substrate using a double-sided adhesive tape is such that after peeling off one release layer (first release layer), the adhesive layer is attached to one substrate (first substrate), then the other After the release layer (second release layer) is peeled off, the other substrate (second substrate) is attached to the adhesive layer. Among these, the adhesive layer is attached to the first substrate after the double-sided adhesive tape and the first substrate that have peeled the first release layer are aligned, and then the roller is touched down to the end of the second release layer. This is done by rotating the roller and pressing the adhesive layer onto the first substrate.

When the adhesive layer is affixed to the first substrate, depressions occur in the second release layer and the adhesive layer where the roller touches down due to the pressure of the roller. In the case where the depression of the adhesive layer is deep, even if the manufacturing process of the bonded substrate is performed under a vacuum condition, bubbles easily remain in the depression. If air bubbles remain between the bonded substrates, even if the air bubbles seem to have disappeared in the autoclave process, the air bubbles are minimized and not completely eliminated. Bubbles may reappear in reliability tests. Thereby, for example, when a bonded substrate is used for a display device, the reliability and display quality of the display device are reduced, and the commercial value is impaired. In addition, when the touchdown pressure is weakened to such an extent that no depression is generated in the second release layer and the adhesive layer where the roller is touched down, the roller slips and the like, It becomes a factor that causes the entrapment of bubbles on the bonding surface of the adhesive layer and the first substrate. The double-sided pressure-sensitive adhesive tape having no base material has room for improvement in that it does not solve such a problem.

Furthermore, since the double-sided pressure-sensitive adhesive tape usually absorbs steps on the surfaces of the substrates to be bonded together, the thickness of a layer (for example, an adhesive layer or a base material) interposed between the bonded substrates is set to about 100 to 200 μm. It is preferable. In the case of a double-sided pressure-sensitive adhesive tape having no substrate, the thickness of the pressure-sensitive adhesive layer needs to be about 100 to 200 μm in order to satisfy the above conditions. That is, the double-sided pressure-sensitive adhesive tape having no base material needs to have a thicker adhesive layer than the double-sided pressure-sensitive adhesive tape of Patent Document 1 having a base material. However, since the adhesive layer is softer than the base material, there is room for improvement in a double-sided adhesive tape that does not have a base material because the thickness of the adhesive layer tends to deepen the depression of the adhesive layer that occurs when the roller is touched down. there were.

The present invention has been made in view of the above situation, and even a double-sided pressure-sensitive adhesive tape that does not have a substrate can suppress the occurrence of a depression in the pressure-sensitive adhesive layer due to the touchdown of a roller, a display device, It is an object of the present invention to provide a method for manufacturing a bonded substrate and a method for manufacturing a display device.

The present inventors have made various studies on double-sided pressure-sensitive adhesive tapes that suppress the occurrence of dents in the pressure-sensitive adhesive layer due to the touchdown of the roller even when the double-sided pressure-sensitive adhesive tape does not have a base material. Focused on the thickness of the. Then, by making the release layer (second release layer) on the side to which the roller is pressed thicker than the release layer (first release layer) to be peeled first, the second release layer is deformed against the pressure of the roller. The inventors have found that the occurrence of depressions in the adhesive layer is suppressed and the above problems can be solved brilliantly, and the present invention has been achieved.

That is, the present invention is a planar double-sided pressure-sensitive adhesive tape used for bonding substrates, wherein the double-sided pressure-sensitive adhesive tape has an adhesive layer sandwiched between a first release layer and a second release layer, and There is no base material, and the second release layer is a double-sided pressure-sensitive adhesive tape that is thicker than the first release layer.

Since the double-sided pressure-sensitive adhesive tape of the present invention does not have a substrate, it is necessary to make the pressure-sensitive adhesive layer thicker than a double-sided pressure-sensitive adhesive tape having a substrate. In this way, when the adhesive layer is thick, there is a concern that deep depressions may occur in the adhesive layer when a rigid body such as a substrate is bonded using a roller. On the other hand, according to the double-sided pressure-sensitive adhesive tape of the present invention, the second release layer is thicker than the first release layer, and the second release layer is not easily deformed by pressure. It can suppress that a depression | dent generate | occur | produces in the adhesion layer by match | combining. Thereby, generation | occurrence | production of the bubble which remain | survives between the bonded rigid bodies can be suppressed.

Moreover, according to the double-sided adhesive tape of this invention, since the 2nd peeling layer cannot change easily with respect to pressurization, the touchdown pressure of a roller can be strengthened. This suppresses misalignment of the adhesive layer attachment position, making it possible to reduce the accuracy of the attachment position to ± 100 μm or less, and the generation of air bubbles in the adhesion surface of the adhesive layer and the rigid body. Can be suppressed.

Furthermore, since the double-sided pressure-sensitive adhesive tape of the present invention does not cause a decrease in transmittance due to the base material and the generation of air bubbles remaining between the bonded substrates is suppressed, the double-sided pressure-sensitive adhesive tape of the present invention is manufactured for display devices. By using the method, a display device with excellent display quality and reliability can be manufactured. Thus, the double-sided pressure-sensitive adhesive tape of the present invention can be particularly suitably used for a display device manufacturing method.

In this specification, adhesion means that two members are joined with a slight pressure. It is preferable that the adhesive layer with which the double-sided adhesive tape of this invention is provided is what can fix two members permanently by hardening by the time passage after affixing, pressurization, etc. FIG. The adhesive layer is preferably transparent and has high transmittance. Thereby, the double-sided adhesive tape of this invention can be used especially suitably for the manufacturing method of a display apparatus. An acrylic resin or the like can be used as the material for the pressure-sensitive adhesive layer that satisfies these conditions.

Moreover, in this specification, a base material is a support body which has the function to hold | maintain an adhesion layer, and is a member which does not have an adhesion function and an adhesion function. Usually, as a material of the base material, a resin film formed of polyester or the like is used.

The constitution of the double-sided pressure-sensitive adhesive tape of the present invention is not particularly limited by other components as long as such a component is formed as essential, but from the first release layer, the adhesive layer and the second release layer. The form is suitable.
The preferable form in the double-sided adhesive tape of this invention is demonstrated in detail below.

Examples of the material of the first and second release layers include a resin film formed of polypropylene or the like. Moreover, the materials of the first and second release layers may be different.

The thickness of the second release layer is preferably 100 μm or more. Thereby, generation | occurrence | production of the hollow by the touchdown of a roller can be suppressed more reliably. In addition, when the thickness of the second release layer exceeds 200 μm, the peelability of the second release layer is lowered, and when the second release layer is peeled off, the adhesive layer is easily recessed and chipped. Therefore, the thickness of the second release layer is preferably 200 μm or less. That is, the thickness of the second release layer is more preferably 100 to 200 μm.

The thickness of the adhesive layer is preferably 100 μm or more. Thereby, the level | step difference of the surface of the board | substrate bonded together can be reliably absorbed also in the double-sided adhesive tape which does not have a base material. In addition, since the adhesion layer is a single layer without a base material when the thickness of an adhesion layer exceeds 200 micrometers, a shape defect will generate | occur | produce when cut into a required shape. Therefore, the thickness of the adhesive layer is preferably 200 μm or less. That is, the thickness of the second release layer is more preferably 100 to 200 μm.

If the thickness of the second release layer is increased, the second release layer is less likely to curl (is less likely to deform), but if the second release layer is made larger than the adhesive layer, the peelability of the second release layer can be improved. When the second release layer is peeled off, it is possible to prevent the adhesive layer from being depressed and chipped. That is, the surface of the second release layer on the adhesive layer side is preferably larger than the surface of the adhesive layer on the second release layer side.

The first release layer may be thinner than the second release layer. Therefore, the thickness of the first release layer may be about 50 μm as in the case of a general release layer. Thereby, since peeling of a 1st peeling layer can be performed easily, when peeling off a 1st peeling layer, it can suppress that it becomes depressed in an adhesion layer and a chip | tip generate | occur | produces.

From the viewpoint of lowering the possibility of dents and chipping when the first release layer is peeled off, the first release layer is made larger than the adhesive layer to release the first release layer. It is preferable to improve the property. That is, the surface of the first release layer on the adhesive layer side is preferably larger than the surface of the adhesive layer on the first release layer side.

The present invention also includes a pair of substrates bonded by the double-sided pressure-sensitive adhesive tape of the present invention, and the pair of substrates is a display device including a substrate disposed on the display surface side of the display panel.

According to the display device of the present invention, it is possible to suppress the generation of bubbles remaining between the pair of bonded substrates, and thus the reliability and display quality of the display device can be improved. Thus, the display device of the present invention can be particularly suitably used for an air gapless structure display device in which a pair of substrates are bonded together.

Note that the term “a pair of bonded substrates includes a substrate disposed on the display surface side of the display panel” means that the combination of the pair of bonded substrates is disposed on the display surface side of the display panel and the display panel. What is necessary is just a combination with the board | substrate arrange | positioned at the combination with a board | substrate or the display surface side of a display panel. Examples of the former include a combination of a display panel and a touch panel, and a combination of a display panel and a cover substrate (protective substrate). Examples of the latter include a combination of a touch panel and a cover substrate. Moreover, the kind of display panel is not specifically limited, For example, a liquid crystal display panel and an organic electroluminescent display panel are mentioned.

The present invention further relates to a method for manufacturing a bonded substrate in which a first substrate and a second substrate are bonded to each other, the manufacturing method comprising: a first release layer; a second release layer thicker than the first release layer; The first release layer is peeled off by a roller using a sheet-like double-sided pressure-sensitive adhesive tape that has an adhesive layer sandwiched between them and does not have a base material. A first bonding step in which the pressure-sensitive adhesive layer is pressure-bonded to the first substrate by pressing the surface from which the peeling layer has been peeled against the first substrate, and the second peeling layer is peeled off after the first bonding step. Furthermore, it is also a method for manufacturing a bonded substrate including a second bonding step in which the second substrate is bonded to the surface of the adhesive layer from which the second release layer has been peeled.

According to the method for producing a bonded substrate of the present invention, since the second release layer is thicker than the first release layer, when the roller is pressed against the second release layer in the first bonding step, the second release layer It becomes difficult to deform | transform, and it can suppress that a dent generate | occur | produces in the adhesion layer. Thereby, generation | occurrence | production of the bubble which remains between bonded substrates can be suppressed.

Moreover, according to the manufacturing method of the bonded substrate of this invention, since the 2nd peeling layer cannot change easily with respect to pressurization, the touchdown pressure of a roller can be strengthened. This suppresses misalignment of the adhesive layer application position, making it possible to reduce the accuracy of the adhesion position to ± 100 μm or less, and entrap air bubbles on the adhesive surface between the adhesive layer and the first substrate. Can be suppressed.

Furthermore, according to the method for manufacturing a bonded substrate of the present invention, the transmittance is not reduced by the base material, and generation of bubbles remaining between the bonded substrates is suppressed. By using this manufacturing method for a manufacturing method of a display device, a display device having excellent display quality and reliability can be manufactured. As described above, the method for manufacturing a bonded substrate according to the present invention can be particularly preferably used for a method for manufacturing a display device, particularly a method for manufacturing a display device having an air gapless structure in which a pair of substrates are bonded together.

The method for producing a bonded substrate of the present invention is not particularly limited as long as such a process is essential and may or may not include other processes. .
The preferable aspect in the manufacturing method of the bonded substrate board of this invention is demonstrated in detail below.

At least one of the first bonding step and the second bonding step is preferably performed under vacuum conditions, and the first bonding step and the second bonding step are performed under vacuum conditions. Is more preferable. Thereby, generation | occurrence | production of the bubble which remain | survives between an adhesion layer and a 1st board | substrate and / or between an adhesion layer and a 2nd board | substrate can be suppressed more reliably.

Note that in this specification, the vacuum is preferably 100 Pa or less.

From the same viewpoint as in the case of the double-sided pressure-sensitive adhesive tape of the present invention, a preferable form of the double-sided pressure-sensitive adhesive tape of the present invention can be used as a preferable aspect of the bonded substrate of the present invention. That is, the thickness of the second release layer is preferably 100 μm or more, and more preferably 100 to 200 μm. Moreover, it is preferable that the thickness of the said adhesion layer is 100 micrometers or more, and it is more preferable that it is 100-200 micrometers. Furthermore, it is preferable that the surface on the adhesive layer side of the second release layer is larger than the surface on the second release layer side of the adhesive layer. And it is preferable that the surface by the side of the said adhesion layer of the said 1st peeling layer is larger than the surface by the side of the said 1st peeling layer of the said adhesion layer.

The present invention is a method for manufacturing a display device using the method for manufacturing a bonded substrate substrate according to the present invention, wherein the first substrate is a display panel or a substrate disposed closer to the display surface than the display panel. The second substrate is also a method for manufacturing a display device, which is a substrate disposed closer to the display surface than the first substrate.

According to the display device manufacturing method of the present invention, it is possible to suppress the generation of bubbles remaining between the bonded substrates, and thus it is possible to manufacture a display device having excellent reliability and display quality. As described above, the method for manufacturing a display device of the present invention can be particularly suitably used for a method for manufacturing a display device having an air gapless structure in which a pair of substrates are bonded together.

Note that examples of the combination of the first substrate and the second substrate include a combination of a display panel and a touch panel, a combination of a display panel and a cover substrate, and a combination of a touch panel and a cover substrate. Moreover, the kind of display panel is not specifically limited, For example, a liquid crystal display panel may be sufficient and an organic electroluminescent display panel may be sufficient.

According to the double-sided pressure-sensitive adhesive tape, the display device, the method for manufacturing a bonded substrate, and the method for manufacturing a display device according to the present invention, even if the double-sided pressure-sensitive adhesive tape does not have a base material, A double-sided pressure-sensitive adhesive tape, a display device, a method for manufacturing a bonded substrate, and a method for manufacturing a display device can be provided.

EXAMPLES Although an Example is hung up below and this invention is demonstrated still in detail with reference to drawings, this invention is not limited only to these Examples.

Example 1
FIG. 1 is an exploded perspective view illustrating the configuration of the display device according to the first embodiment.

As shown in FIG. 1, in the display device of Example 1, the cover substrate 2 and the touch panel 3 are bonded together with a transparent adhesive layer 12, and the back side of the touch panel 3 (the side opposite to the cover substrate 2) An AR film (antireflection film) 5, a gasket 6 and a bezel 7 are laminated in this order from the cover substrate 2 side. Although not shown, a display panel is disposed between the gasket 6 and the bezel 7.

The cover substrate 2 is a substrate for protecting the touch panel 3, the display panel, and the like from dust and impact, and a transparent material such as glass can be suitably used. The cover substrate 2 of the present embodiment is a cover glass, and has a transparent window portion 21 and a black edge portion 22 that is a light-shielding portion provided around the window portion 21.

A printed circuit board 4 is connected to the touch panel 3. In this embodiment, since a cover glass is used as the cover substrate 2, the touch panel 3 is not the resistive film type (for example, the electrostatic capacity type). When a plastic substrate having a thickness of about 0.8 mm is used as the cover substrate 2, the touch panel 3 can be a resistive film.

The AR film 5 is a member provided to prevent the incident light on the display area from being reflected and deteriorating the display quality, and a transparent film made of a metal oxide, a fluorine-containing compound, or the like can be used. . Examples of the method of forming the AR film 5 include sputtering, chemical vapor deposition (CVD), physical vapor deposition (PVD) and other vapor deposition methods, a method of applying an antireflection film material by dipping, a method of applying a low reflection film, and the like. It is done.

The display panel is a member that performs image display in the display device, and a liquid crystal display panel is used in this embodiment. In the liquid crystal display panel, a liquid crystal layer is disposed between the color filter substrate and the thin film transistor substrate, and a polarizing plate is provided on the side opposite to the liquid crystal layer of the color filter substrate and the thin film transistor substrate.

The gasket 6 is a member that suppresses damage to the display panel due to contact with the bezel 7 that is a rigid body, and increases adhesion between the bezel 7 and the display panel. Although it does not specifically limit as a material of the gasket 6, For example, the cushioning property with respect to an impact is high, and a cheap urethane foam can be used suitably.

FIG. 2 is a schematic diagram of a double-sided pressure-sensitive adhesive tape used in the manufacturing process of the display device of Example 1, (a) is a schematic plan view, and (b) is a schematic sectional view taken along line X1-Y1 in (a). FIG. As shown in FIG. 2B, the double-sided pressure-sensitive adhesive tape 1 has a thickness of a protective film (first release layer 10) having a thickness of 50 μm and a protective film (second release layer) 12 having a thickness of 125 μm. A transparent adhesive layer 11 having a thickness of 100 μm is sandwiched between the protective film 12 and the protective film 12. The protective film 12 has a positioning mark 13. In this embodiment, polyethylene terephthalate (PET) is used as the material of the protective films 10 and 12. In addition, an acrylic adhesive material was used as the material of the adhesive layer 11.

The planar dimensions of the protective films 10 and 12 are shown in FIG. As shown in FIG. 2A, the protective films 10 and 12 have a larger planar shape than the adhesive layer 11. Thereby, peeling of the protective films 10 and 12 can be performed easily. In the present embodiment, since the protective film 12 is thicker than the protective film 10, there is a concern that it will be difficult to peel off. On the other hand, the said concern is eliminated by making the protective film 12 larger than the protective film 10, and improving the peelability of the protective film 12. FIG.

Hereinafter, a method for manufacturing the display device of Example 1 will be described. FIGS. 3A and 3B are schematic views illustrating a double-sided pressure-sensitive adhesive tape attaching process in the manufacturing process of the display device of Example 1. FIG.

First, after peeling off the protective film 10 of the double-sided pressure-sensitive adhesive tape 1 and cleaning the surface to be bonded to the cover substrate 2 of the touch panel 3, the double-sided pressure-sensitive adhesive tape 1 and the touch panel 3 were aligned. Next, under a vacuum condition of 10 to 100 Pa, as shown in FIGS. 3A and 3B, the roller head (roller) 8 is touched down to the end of the protective film 12, and then the roller head 8 is moved. The adhesive layer 11 was affixed to the touch panel 3 by rotating and pressing the adhesive layer 11 to the touch panel 3 through the protective film 12. The operating conditions of the roller head 8 were a pressure of 0.2 MPa, a moving speed of 50 mm / s, and a roller diameter of 20 mm (20φ). At this time, as shown in FIG. 3 (b), depressions occurred in the protective film 12 and the adhesive layer 11 at the portion where the roller head 8 was touched down.

Next, after peeling off the protective film 12, the cover substrate 2 and the touch panel 3 were bonded together by pressing the cover substrate 2 to the adhesive layer 11 under a vacuum condition of 10 to 100 Pa. Next, after the AR film 5 was attached to the back side of the touch panel 3, autoclaving was performed to remove remaining bubbles. Thereafter, the display device of Example 1 was completed by laminating the gasket 6, the display panel, and the bezel 7 in this order.

(Comparative Example 1)
A display device of Comparative Example 1 was produced in the same manner as Example 1 except that the double-sided adhesive tape used for bonding the cover substrate 2 and the touch panel 3 was changed. FIG. 4 is a schematic cross-sectional view of a double-sided pressure-sensitive adhesive tape used in the manufacturing process of the display device of Comparative Example 1. FIGS. 5A and 5B are schematic views showing a double-sided adhesive tape attaching step in the manufacturing process of the display device of Comparative Example 1. FIG.

As shown in FIG. 4, the double-sided pressure-sensitive adhesive tape 9 of Comparative Example 1 includes a protective film (first release layer) 90 having a thickness of 50 μm and a protective film (second release layer) 92 having a thickness of 125 μm. A transparent adhesive layer 11 having a thickness of 100 μm is sandwiched. The planar dimensions of the protective films 90 and 92 were the same as the planar dimensions of the adhesive layer 11. The protective films 90 and 92 are obtained by changing only the film thickness and size of the protective films 10 and 12 of the double-sided pressure-sensitive adhesive tape 1 used in Example 1.

As shown in FIGS. 5 (a) and 5 (b), when the adhesive layer 11 is attached to the touch panel 3 in the same manner as in Example 1, the protective film 92 and the adhesive layer at the portion where the roller head 8 is touched down. Indentation 11 occurred.

Here, the results of comparison between Example 1 and Comparative Example 1 with respect to the depression generated in the adhesive layer 11 will be described. 6 is an interference photograph showing the state of the depression of the adhesive layer generated in the manufacturing process of the display device of Example 1, and FIG. 7 is the view of the depression of the adhesive layer generated in the manufacturing process of the display device of Comparative Example 1. It is an interference photograph which shows a state. 6 and 7, the color shading indicates the degree of the depth of the depression, and the depression becomes deeper as the color becomes darker. Also, the A1 line and B1 line in FIG. 6, the A2 line and B2 line in FIG. 7 correspond to the A1 line and B1 line in FIG. 3B, and the A2 line and B2 line in FIG. 5B, respectively. Yes. That is, the widths of the A1 line and the B1 line and the widths of the A2 line and the B2 line indicate the width of the depression of the adhesive layer 11 in Example 1 and the width of the depression of the adhesive layer 11 in Comparative Example 1, respectively.

When comparing FIGS. 6 and 7, since the overall color of FIG. 6 is lighter and the width of the darker portion is smaller, the depression generated in the adhesive layer 11 in Example 1 is wider and shallower. I understood that. On the other hand, it was found that the depression generated in the adhesive layer 11 in Comparative Example 1 was narrow and deep. That is, in Example 1, the change in the thickness of the adhesive layer 11 was less than that in Comparative Example 1. From this result, it was found that the display device of Example 1 had a wider production margin than the display device of Comparative Example 1.

As a result of inspection after bonding using a backlight, since the depression of the adhesive layer was shallow in Example 1, no bubbles remained on the bonding surface. On the other hand, in Comparative Example 1, since the depression of the adhesive layer was deep, bubbles remained on the bonding surface, and the generation rate of the bubbles was high. From this result, it was found that the display device of Example 1 was higher in quality than the display device of Comparative Example 1 in that no deterioration in display quality due to bubbles was observed.

As a result of performing a reliability test of leaving in a constant temperature bath maintained at 65 ° C. and 90% humidity for 240 hours, no bubbles were generated in the display device of Example 1, whereas in the display device of Comparative Example 1, Bubbles were generated. In addition, as a result of performing a reliability test of leaving in a constant temperature bath maintained at 80 ° C./RH for 12 hours, bubbles were not generated in the display device of Example 1, whereas bubbles were generated in the display device of Comparative Example 1. Occurred. Note that RH is an abbreviation for Relative Humidity, and means humidity in an atmosphere in which a humidification operation and a drying operation are not performed. From these results, it was found that the display device of Example 1 was more reliable than the display device of Comparative Example 1.

1 is an exploded perspective view illustrating a configuration of a display device of Example 1. FIG. It is a schematic diagram of the double-sided adhesive tape used at the manufacturing process of the display apparatus of Example 1, (a) is a plane schematic diagram, (b) is a cross-sectional schematic diagram in the X1-Y1 line | wire of (a). (A), (b) is a schematic diagram which shows the sticking process of the double-sided adhesive tape in the manufacturing process of the display apparatus of Example 1. FIG. It is a cross-sectional schematic diagram of the double-sided adhesive tape used in the manufacturing process of the display device of Comparative Example 1. (A) (b) is a schematic diagram which shows the sticking process of the double-sided adhesive tape in the manufacturing process of the display apparatus of the comparative example 1. FIG. 3 is an interference photograph showing a state of a depression of an adhesive layer generated in the manufacturing process of the display device of Example 1. It is an interference photograph which shows the state of the hollow of the adhesion layer which generate | occur | produced in the manufacturing process of the display apparatus of the comparative example 1.

Explanation of symbols

1: Double-sided adhesive tape 2: Cover substrate 3: Touch panel 4: Printed circuit board 5: AR film (antireflection film)
6: Gasket 7: Bezel 8: Roller head (roller)
9: Double-sided adhesive tape 10: Protective film (first release layer)
11: Adhesive layer 12: Protective film (second release layer)
13: Positioning mark 21: Window portion 22: Black edge portion 91: Protective film (first release layer)
92: Protective film (second release layer)

Claims (11)

It is a sheet-like double-sided adhesive tape used for bonding substrates,
The double-sided pressure-sensitive adhesive tape has an adhesive layer sandwiched between the first release layer and the second release layer, and does not have a substrate.
The double-sided pressure-sensitive adhesive tape, wherein the second release layer is thicker than the first release layer. The double-sided pressure-sensitive adhesive tape according to claim 1, wherein the second release layer has a thickness of 100 μm or more. The double-sided pressure-sensitive adhesive tape according to claim 1 or 2, wherein the adhesive layer has a thickness of 100 µm or more. The double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 3, wherein a surface of the second release layer on the adhesive layer side is larger than a surface of the adhesive layer on the second release layer side. A pair of substrates bonded by the double-sided pressure-sensitive adhesive tape according to any one of claims 1 to 4,
The pair of substrates includes a substrate disposed closer to the display surface than the display panel. A method for manufacturing a bonded substrate obtained by bonding a first substrate and a second substrate,
The production method uses a planar double-sided pressure-sensitive adhesive tape in which an adhesive layer is sandwiched between a first release layer and a second release layer that is thicker than the first release layer, and has no substrate.
The first release layer is peeled off, and the surface of the pressure-sensitive adhesive layer from which the first release layer is peeled is pressed against the first substrate by a roller over the second release layer. A first bonding step for crimping to
After the first bonding step, including a second bonding step of peeling the second release layer and further sticking the second substrate to the surface of the adhesive layer from which the second release layer has been peeled off. The manufacturing method of the bonded substrate characterized by these. The method for manufacturing a bonded substrate according to claim 6, wherein at least one of the first bonding step and the second bonding step is performed under a vacuum condition. The method for manufacturing a bonded substrate according to claim 6 or 7, wherein the thickness of the second release layer is 100 µm or more. The method for manufacturing a bonded substrate according to claim 6, wherein the adhesive layer has a thickness of 100 μm or more. The surface of the said adhesion layer side of said 2nd peeling layer is larger than the surface by the side of the said 2nd peeling layer of the said adhesion layer, The manufacturing of the bonded substrate in any one of Claims 6-9 characterized by the above-mentioned. Method. A method for manufacturing a display device using the method for manufacturing a bonded substrate according to claim 6,
The first substrate is a display panel or a substrate disposed on the display surface side of the display panel,
The method for manufacturing a display device, wherein the second substrate is a substrate disposed closer to the display surface than the first substrate.