JP2020152773A - Pressure-sensitive adhesive sheet, pressure-sensitive adhesive sheet laminate with release film, laminate for configuring image display device, and image display device using the same - Google Patents

Abstract

To provide a pressure-sensitive adhesive sheet which has durability such as reliability of foaming resistance and flexibility such as level difference absorbing property, and further has cutting workability applicable to a complicated shape such as a shape formed by notching a part of an end part or a central part.SOLUTION: A pressure-sensitive adhesive sheet has one or two or more hard parts 2 exhibiting any shape, in plan view of a sheet surface, selected from a group comprising (a) frame-like, (b) island-like, (c) belt-like, and (d) network-like in the sheet surface, in which the hard part includes a predetermined cutting line 4 in its region and has an outline separated from the predetermined cutting line 4 to the outside by 0.15 to 4 mm, a gel fraction of the hard part 2 is 40-100%, and the hard part 2 has a gel fraction relatively larger than that of any site other than the hard part 2 in the sheet surface.SELECTED DRAWING: Figure 1

Description

The present invention comprises an adhesive sheet used in an image display device such as a liquid crystal display (LCD), an organic EL display device (OLED), and a plasma display (PDP), and an adhesive sheet with a release film provided with the adhesive sheet. The present invention relates to a body, a laminate for configuring an image display device, and an image display device using these.

In recent years, the market for devices having an image display device with a surface protection panel on the front, such as smartphones, tablet computers, televisions, digital signage, game machines, vending machines, electronic blackboards, and car navigation systems, has grown rapidly.
In an image display device provided with these surface protection panels, for example, components for an image display device such as a surface protection panel, a touch panel, and an image display panel are often joined via an adhesive sheet.

By the way, the surface protection panel may have irregularities on the surface protection panel surface, such as having a printing step on the surface protection panel surface other than the visible opening surface portion by black printing or white printing. Therefore, the adhesive sheet for joining these is required to have flexibility that can be deformed by following the unevenness. When a surface protection panel having such irregularities is attached to an adhesive sheet having a high elastic modulus, air bubbles are generated around the irregularities, or an image is displayed due to distortion due to stress at the time of attachment to the image display device. The screen displayed by the device may be uneven.
On the other hand, a simply flexible adhesive sheet may have problems of foaming or peeling at the bonding interface when exposed to a high temperature and high humidity environment or a sudden temperature change.
Therefore, in order to solve such a problem of foaming / peeling, it is necessary to design the adhesive sheet to be relatively hard and have high cohesive force.

From this point of view, for example, in Patent Document 1, it is possible to obtain followability to a stepped portion and surface flatness, and firmly with high cohesive force without causing distortion or deformation even in a light opaque portion. As a new pressure-sensitive adhesive sheet that can be bonded and has a non-sticky adhesive surface, a pressure-sensitive adhesive sheet having a soft portion having a gel fraction of less than 1% and a hard portion having a gel fraction of 40% or more has been proposed.

Japanese Unexamined Patent Publication No. 2016-22925

In recent years, with the miniaturization, full-scale, narrowing of the frame, etc. of mobile devices, a part of the display is cut out, a hole is made, or a complicated shape is adopted.
Since microphones, cameras, buttons, and other sensors are located in these notches and holes (processed areas), the shape of the display is also the shape of the adhesive sheet that joins the components for the image display device. Therefore, the appropriateness of notch processing is required.
Moreover, the processing area of the display extends to the central area of the display, that is, the image display portion, and the shape becomes more and more complicated. Therefore, the adhesive sheet is required to have higher processing suitability than ever before. There is.

On the other hand, recently, a foldable display has been developed as a new form of a display, and a foldable property is also required for an adhesive sheet for joining a component for an image display device.

Therefore, an object of the present invention is to have durability such as foaming reliability, and to have a cutting processability that can be applied to a complicated shape such as a shape in which a part of an end portion or a central portion is cut out. It is an object of the present invention to provide a new pressure-sensitive adhesive sheet having bending characteristics.

The present invention is selected as the first adhesive sheet from the group consisting of (a) frame-shaped, (b) island-shaped, (c) strip-shaped and (d) mesh-shaped when the sheet surface is viewed in a plan view. It has one or two or more hard portions in the sheet surface having the shape of the above, and the hard portion includes a line to be cut (referred to as a “planned cutting line”) in the region and said. It has a contour located 0.15 mm to 4 mm outside the planned cutting line, its gel fraction is 40 to 100%, and a part other than the hard part (“normal part”) in the sheet surface. We propose an adhesive sheet characterized by having a relatively larger gel fraction than (referred to as).

The present invention also relates to the first method for producing an adhesive sheet, wherein the sheet surface of the photocurable adhesive sheet has a size capable of covering the entire surface of the sheet and shields light. After covering a masking sheet having a window portion having the same shape as the hard portion at a position where the hard portion can be formed, the surface covered with the masking sheet is irradiated with light to partially cover the curable adhesive sheet. We propose a method for producing an adhesive sheet, which is characterized by being effectively cured.

The present invention also provides, as a second adhesive sheet, one or repeatedly bendable soft portion that is continuous across the upper and lower edge portions, the left and right edge portions, or both when the sheet surface is viewed in a plan view. Two or more of the soft portions in the sheet surface, the soft portion has a width of 1 mm to 30 mm, the glass transition temperature thereof is -50 ° C to -20 ° C, and the soft portion in the sheet surface. We propose an adhesive sheet characterized in that the glass transition temperature is relatively lower than that of other parts (referred to as "normal parts").

The present invention also relates to the above-mentioned second method for producing an adhesive sheet, which is a photocurable adhesive sheet and has a glass transition temperature of −50 ° C. to −20 ° C. (“soft adhesive sheet”). (Also also referred to as) and a pressure-sensitive adhesive sheet that is photocurable and has a glass transition temperature relatively higher than that of the soft pressure-sensitive adhesive sheet (also referred to as “normal portion pressure-sensitive adhesive sheet”) are heat-sealed. We propose a method for producing an adhesive sheet, which comprises irradiating light to cure the adhesive sheet.

The present invention also relates to the above-mentioned second method for producing an adhesive sheet, which is a photocurable adhesive and has a glass transition temperature of −50 ° C. to −20 ° C. (“soft adhesive”). (Also also referred to as), and a pressure-sensitive adhesive that is photocurable and has a glass transition temperature relatively higher than that of the soft pressure-sensitive adhesive (also referred to as “normal portion pressure-sensitive adhesive”) are die-coated. We propose a method for producing an adhesive sheet, which comprises obtaining a photocurable adhesive sheet and further irradiating the photocurable adhesive sheet with light to cure the adhesive sheet.

The present invention also has, as the third pressure-sensitive adhesive sheet, the hard portion and the soft portion in the sheet surface of the first and second pressure-sensitive adhesive sheets, and the hard portion has a gel fraction of 40 to 100. %, And the gel fraction is relatively larger than that of the hard part and the normal part.
We propose an adhesive sheet in which the glass transition temperature of the soft portion is −50 ° C. to −20 ° C. and the glass transition temperature is relatively lower than that of the normal portion.

The present invention also relates to the above-mentioned third method for producing an adhesive sheet, which is a photocurable adhesive sheet and has a glass transition temperature of −50 ° C. to −20 ° C. (“soft adhesive sheet”). (Also also referred to as) and a pressure-sensitive adhesive sheet that is photocurable and has a glass transition temperature relatively higher than that of the soft pressure-sensitive adhesive sheet (also referred to as “normal portion adhesive sheet”) is heat-sealed. The sheet surface of the photocurable adhesive sheet thus obtained was first irradiated with light to partially cure the curable adhesive sheet, and then the curable adhesive sheet was partially cured.
Next, the sheet surface of the photocurable adhesive sheet is coated with a masking sheet having a size and shape that can shield light and match the shapes of the normal portion and the soft portion. We propose a method for producing an adhesive sheet, which comprises partially curing the curable adhesive sheet by secondarily irradiating a surface coated with the masking sheet with light.

The present invention also relates to the above-mentioned third method for producing an adhesive sheet, which is a photocurable adhesive and has a glass transition temperature of −50 ° C. to −20 ° C. (“soft adhesive”). (Also also referred to as) and a pressure-sensitive adhesive that is photocurable and has a glass transition temperature relatively higher than that of the soft pressure-sensitive adhesive (also referred to as “normal part pressure-sensitive adhesive”). After primary irradiation of the sheet surface of the photocurable adhesive sheet with light to partially cure the curable adhesive sheet,
Next, the sheet surface of the photocurable adhesive sheet is coated with a masking sheet having a size and shape that can shield light and match the shapes of the normal portion and the soft portion. We propose a method for producing an adhesive sheet, which comprises partially curing the curable adhesive sheet by secondarily irradiating a surface coated with the masking sheet with light.

The first and third adhesive sheets proposed by the present invention have a relatively high gel fraction, which includes a planned cutting line in the region and has a contour located outside a predetermined width from the planned cutting line. Since it has a hard portion, it can be suitably cut along the planned cutting line, so that it has excellent cutting workability and can perform complicated processing.
Further, the normal part other than the hard part has a relatively low gel fraction, and therefore has excellent step absorption. Finally, by photo-curing, the cohesive force can be increased and the durability such as foam resistance can be enhanced.
Therefore, it is possible to process the image display unit with high accuracy according to the holes and cutouts corresponding to the installation of the camera, microphone, and sensor.

On the other hand, the second and third adhesive sheets proposed by the present invention have a width of 1 mm to 30 mm, which is continuous between the upper and lower end edges and / or between the left and right edge edges and has a relatively low glass transition temperature. Since it has a soft portion, it can be bent along the soft portion.
Furthermore, since the gel fraction of the normal part other than the soft part is relatively high, not only the adhesive surface does not become sticky even in a harsh environment such as high temperature and high humidity, but also air bubbles etc. in the durability test such as a moist heat environment. It is unlikely to cause poor appearance.
Then, by finally photocuring, the cohesive force can be increased and the durability such as foaming reliability can be enhanced. Therefore, it can be suitably used for bonding foldable devices.

It is a top view which showed an example of the pressure-sensitive adhesive sheet which concerns on Example of this invention. It is a top view which showed the other example of the pressure-sensitive adhesive sheet which concerns on Example of this invention. It is a top view which showed the further example of the pressure-sensitive adhesive sheet which concerns on Example of this invention. It is a top view which showed the further example of the pressure-sensitive adhesive sheet which concerns on Example of this invention. It is a top view which showed the further example of the pressure-sensitive adhesive sheet which concerns on Example of this invention. It is a top view which showed the further example of the pressure-sensitive adhesive sheet which concerns on Example of this invention. It is a top view which showed the further example of the pressure-sensitive adhesive sheet which concerns on Example of this invention. It is a top view which showed the further example of the pressure-sensitive adhesive sheet which concerns on Example of this invention.

<This adhesive sheet 1>
As an example of the pressure-sensitive adhesive sheet according to the embodiment of the present invention, it is a pressure-sensitive adhesive sheet that is partially photo-cured, and when the sheet surface is viewed in a plan view, as shown in FIGS. An adhesive sheet 1 having one or more hard portions 2 (referred to as “the present adhesive sheet 1”) can be mentioned.

The pressure-sensitive adhesive sheet 1 may be a pressure-sensitive adhesive sheet having a rectangular shape, or may be a pressure-sensitive adhesive sheet wound in a roll shape.

The hard portion 2 is a portion, that is, a region in the sheet surface characterized by having a relatively larger gel fraction than a portion 3 (referred to as “normal portion 3”) other than the hard portion 2.
The gel fraction of the hard portion 2 exerts a high cohesive force to enhance the adhesiveness, and while the adhesive surface does not become sticky even in a harsh environment such as high temperature and high humidity, the adhesiveness with the interface is enhanced at the time of bonding. From this point of view, it is preferably 40 to 100%, particularly preferably 60% or more or 80% or less, and particularly preferably 65% or more or 75% or less.

On the other hand, the gel fraction of the normal portion 3 is preferably 0 to 80% or more, particularly 0% or more or 70%, from the viewpoint of enhancing the adhesion with the interface at the time of bonding and ensuring the step absorption. Hereinafter, among them, 0% or more or 60% or less is particularly preferable.

As a method for measuring the gel fraction, extraction with a solvent can be mentioned.
The specific method for measuring the gel fraction is as follows.
First, about 0.05 g of each adhesive sheet is collected, wrapped in a bag shape with a stainless steel (SUS) mesh (# 200) whose mass (X) has been measured in advance, the mouth of the bag is folded and closed, and the mass of this package is obtained. (Y) is measured.
Then, it is immersed in 100 ml of ethyl acetate, stored in the dark at 23 ° C. for 24 hours, then the package is taken out and heated at 70 ° C. for 4.5 hours to evaporate the adhered ethyl acetate.
Finally, the mass (Z) of the dried package is measured, and the obtained mass is substituted into the following formula to obtain the result.
Gel fraction [%] = [(ZX) / (YX)] x 100
However, when the gel fraction is high, the adhesive sheet may be appropriately crushed and used for extraction.
The same applies to the gel fraction in other embodiments.

High cohesive force when the tan δ peak temperature of the hard portion 2, that is, the glass transition temperature (Tg [H]) determined by the temperature dispersion measurement of the shear viscoelasticity measuring device (leometer) is -60 to + 20 ° C. The glass transition temperature (Tg [H]) of the hard portion 2 is preferably −60 to + 20 ° C., particularly −55 ° C. or higher or + 15 ° C. or lower, and particularly −50 ° C. or higher or + 10 ° C. The following is particularly preferable.

The hard portion 2 may be the hard portion 2 (a) having a frame shape as shown in FIG. 1 when the sheet surface is viewed in a plan view, or the hard portion 2 having an island shape as shown in FIG. It may be (b), it may be a hard portion 2 (c) having a band shape as shown in FIG. 3, or it may be a hard portion 2 (d) having a mesh shape as shown in FIG. It may be a hard portion having another shape.
In addition, "frame shape" means a shape that surrounds the circumference, and "island shape" means the surroundings (excluding a part of the circumference when a part of the circumference constitutes the periphery of the sheet). It means a shape surrounded by an area of, for example, a normal part.
The adhesive sheet 1 has one or two hard portions having any shape selected from the group consisting of (a) frame-shaped, (b) island-shaped, (c) strip-shaped, and (d) mesh-shaped. It is preferable to have the above in the sheet surface.
However, the shape of the hard portion 2 is not limited to these.

From the viewpoint of industrially feasible punching accuracy, the hard portion 2 has a size that fits within a circle having a diameter of 0.3 mm to 20 mm, or has a narrowest width of 0.3 mm to 20 mm. You may.
Above all, the hard portion may have a size within a circle having a diameter of 0.5 mm or more or 15 mm or less, and among them, a diameter of 1.0 mm or more or 10 mm or less.
Alternatively, the narrowest width may be 0.5 mm or more or 15 mm or less in diameter, and 1.0 mm or more or 10 mm or less in diameter.

From the viewpoint of further improving the cutting workability, the hard portion 2 includes a line to be cut (referred to as "planned cutting line") in the region, and is 0.15 mm to 4 mm from the planned cutting line. It is preferable to have a contour located on the outside.
Above all, it is more preferable to have a contour located 0.2 mm or more or 3 mm or less, and more preferably 0.3 mm or more or 1 mm or less outside the planned cutting line.

The thickness of the adhesive sheet 1 is preferably 0.010 mm to 0.5 mm, particularly 0.020 mm or more or 0.2 mm or less, and 0.025 mm or more or 0.175 mm among them, from the viewpoint of ensuring processing accuracy. The following is more preferable.

The adhesive sheet 1 may be a sheet composed of a single layer or a multilayer sheet in which two or more layers are laminated.

<Book adhesive sheet 10>
As another example of the pressure-sensitive adhesive sheet according to the embodiment of the present invention, it is a pressure-sensitive adhesive sheet that is partially photo-cured, and is soft in the sheet surface as shown in FIGS. 5 to 8 when the sheet surface is viewed in a plan view. An adhesive sheet having one or more parts 5 (referred to as “the present adhesive sheet 10”) can be mentioned.

The pressure-sensitive adhesive sheet 10 may be a pressure-sensitive adhesive sheet having a rectangular shape, or may be a pressure-sensitive adhesive sheet wound in a roll shape.

The soft portion 5 is a portion or region characterized in that the glass transition temperature is relatively lower than that of the portion 6 (referred to as “normal portion 6”) other than the soft portion 5 in the sheet surface.
The glass transition temperature (Tg [H]) of the soft portion 5 is preferably −50 to −20 ° C., particularly −45 ° C. or higher or −25 ° C. or lower, particularly among them, because high flexibility can be obtained. It is particularly preferable that the temperature is −40 ° C. or higher or −30 ° C. or lower.
The glass transition temperature of the soft portion 5 is a value measured as the peak temperature of Tan δ obtained by the temperature dispersion measurement of the shear viscoelasticity measuring device (rheometer), as in the case of the hard portion 2.
The gel fraction of the soft portion 5 is preferably 10 to 80%, particularly 40%, from the viewpoints of followability to the stepped portion, surface flatness, and the ability to alleviate distortion and deformation in the sheet. It is particularly preferably more than or less than 75%, and more preferably 50% or more or 70% or less.

On the other hand, the glass transition temperature (Tg [H]) of the normal portion 6 exerts a high cohesive force to enhance the adhesiveness, and the adhesive surface does not become sticky even in a harsh environment such as high temperature and high humidity, but at the time of bonding. From the viewpoint of enhancing the adhesion to the interface, it is preferably relatively higher than that of the soft portion 5, specifically, it is preferably 45 to + 20 ° C, and above all, -40 ° C or higher or +15. It is particularly preferable that the temperature is ℃ or less, and more preferably -30 ℃ or more or + 10 ℃ or less.
Similar to the hard portion 2 and the soft portion 5, the glass transition temperature of the normal portion 6 is a value measured as the peak temperature of Tan δ obtained by the temperature dispersion measurement of the shear viscoelasticity measuring device (rheometer). ..

In the adhesive sheet 10, as shown in FIGS. 5 to 7, the soft portion 5 is continuous between the upper and lower end edges, between the left and right edge portions, or both when the sheet surface is viewed in a plan view. It is preferably a soft portion that can be repeatedly bent.

The adhesive sheet 10 may have a plurality of the soft portions 5 in the sheet surface.

The soft portion 5 preferably has a width of 1 mm to 30 mm, particularly preferably 2 mm or more or 25 mm or less, and more preferably 3 mm or more or 20 mm or less, from the viewpoint of covering a portion that is curved at the time of bending. ..

The thickness of the pressure-sensitive adhesive sheet 10 is preferably 0.01 mm to 0.15 mm, particularly 0.02 mm or more or 0.12 mm or less, and 0.025 mm or more or 0.1 mm among them, from the viewpoint of bending durability. The following is more preferable.

In the adhesive sheet 10, the ratio of the width of the soft portion 5 to the thickness of the sheet (width of the soft portion 5 / thickness of the adhesive sheet 10) prevents the soft portion and the non-soft portion from interfering with each other during bending. From the viewpoint of avoidance, it is preferably 50 to 1200, particularly preferably 100 or more or 1000 or less, and particularly preferably 200 or more or 900 or less.

The adhesive sheet 10 may be a sheet composed of a single layer or a multilayer sheet in which two or more layers are laminated.

<Book adhesive sheet 20>
As another example of the pressure-sensitive adhesive sheet according to the embodiment of the present invention, it is a pressure-sensitive adhesive sheet that is partially photo-cured, and when the sheet surface is viewed in a plan view, as shown in FIG. 8, the hard portion 2 is inside the sheet surface. An adhesive sheet having one or two or more and having one or two or more soft portions 5 in the sheet surface (referred to as “the present adhesive sheet 20”) can be mentioned.

The pressure-sensitive adhesive sheet 20 may be a pressure-sensitive adhesive sheet having a rectangular shape, or may be a pressure-sensitive adhesive sheet wound in a roll shape.

The characteristics of the shape and size of the hard portion 2 in the adhesive sheet 20 are preferably the same as those of the hard portion 2 in the adhesive sheet 1.
Further, the characteristics of the shape and size of the soft portion 5 of the pressure-sensitive adhesive sheet 20 are preferably the same as those of the soft portion 5 of the pressure-sensitive adhesive sheet 10.

The gel fraction of the hard part 2 in the adhesive sheet 20 exerts a high cohesive force to enhance the adhesiveness, and while the adhesive surface does not become sticky even in a harsh environment such as high temperature and high humidity, it is in contact with the interface at the time of bonding. From the viewpoint of enhancing the adhesiveness, it is preferable that the gel fraction is relatively larger than that of the parts other than the hard part 2 and the soft part 5 (referred to as “normal part”), and the gel fraction is 40 to 100%. Is preferable, and more preferably 60% or more or 80% or less, and more preferably 65% or more or 75% or less.
Further, since the glass transition temperature (Tg [H]) of the soft portion 5 can obtain high flexibility, it is preferable that the glass transition temperature is relatively lower than that of the normal portion, and -50 to -50. The temperature is preferably −20 ° C. or higher, particularly preferably −45 ° C. or higher or −25 ° C. or lower, and particularly preferably −40 ° C. or higher or −30 ° C. or lower.

In the adhesive sheet 20, the ratio of the width of the soft portion 5 to the thickness of the sheet (width of the soft portion 5 / thickness of the adhesive sheet 20) prevents the soft portion and the non-soft portion from interfering with each other during bending. From the viewpoint of avoidance, it is preferably 50 to 1200, and particularly preferably 100 or more or 1000 or less, and particularly preferably 200 or more or 900 or less.

The pressure-sensitive adhesive sheet 20 may be a single-layer sheet or a multi-layer sheet in which two or more layers are laminated.

<Manufacturing method of this adhesive sheet 1>
An example of the manufacturing method of the present adhesive sheet 1 will be described.
However, the manufacturing method of the present adhesive sheet 1 is not limited to the following manufacturing method example.

As an example of the method for producing the present adhesive sheet 1, the sheet surface of the photocurable adhesive sheet has a size capable of covering the entire surface of the sheet surface, can block light, and is described above. After covering a masking sheet having a window portion having the same shape as the hard portion at a position where the hard portion is formed, the surface coated with the masking sheet is irradiated with light to partially cure the curable adhesive sheet, that is, A method of manufacturing the present adhesive sheet 1 can be mentioned by curing the window portion to form the hard portion 2.
The "same shape" does not require strict identity, but means that the shape and size are substantially the same as the window portion, for example, when the external dimensions are completely the same as the window portion. , Including the case where the size is such that a peripheral portion is slightly added to this.
The photocurable adhesive sheet will be described later.

As the material of the masking sheet, for example, a release sheet using polyethylene terephthalate as a base polymer, a film in which an ultraviolet absorber is kneaded into a polyethylene terephthalate film or a polyolefin film, or a film in which an ultraviolet absorber is applied to the surface is used. It is particularly preferable to use a release sheet that does not transmit light used for photocuring, such as a release sheet.
The material of the masking sheet is the same as that of the masking sheet used in the methods for manufacturing the adhesive sheets 10 and 20 described later.

Examples of the light to be irradiated include active energy rays such as ultraviolet rays, electron beams, visible rays, X-rays, and ion rays, and it is preferable to appropriately select the light according to the photopolymerization initiator used. Among them, from the viewpoint of versatility, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable.

As the light source of ultraviolet rays, for example, a high-pressure mercury lamp, a metal halide lamp, a xenon arc lamp, a carbon arc lamp, or the like can be used.
Dose of ultraviolet light is preferably irradiated with ultraviolet light so that the integrated quantity of light wavelength 365nm is ^{1000mJ / cm 2 ~10000mJ / cm 2} , inter alia 1500 mJ / cm ² or more, or 6000 mJ / cm ² or less, 2000 mJ / cm ² among them It is particularly preferable to irradiate with ultraviolet rays so as to be equal to or more or 4000 mJ / cm ² or less.

<Manufacturing method of this adhesive sheet 10>
Next, an example of the manufacturing method of the present adhesive sheet 10 will be described.
However, the manufacturing method of the present adhesive sheet 10 is not limited to the following manufacturing method example.

As an example of the method for producing the present adhesive sheet 10, it is a photocurable adhesive sheet and has a glass transition temperature of −50 ° C. to −20 ° C., and has a size and shape matching the soft portion 5. The soft adhesive sheet and the normal portion adhesive sheet having a size and shape suitable for the normal portion 6 which is a photocurable curable adhesive sheet and whose glass transition temperature is relatively higher than that of the soft adhesive sheet are heated. A method of producing the present pressure-sensitive adhesive sheet 10 by fusing and irradiating light to cure the curable pressure-sensitive adhesive sheet can be mentioned.
The photocurable adhesive sheet will be described later.

Further, as another example of the method for producing the present pressure-sensitive adhesive sheet 10, a pressure-sensitive adhesive that is photocurable and has a glass transition temperature of −50 ° C. to −20 ° C. (also referred to as “soft pressure-sensitive adhesive”). (Referred to as) and a pressure-sensitive adhesive that is photocurable and has a glass transition temperature relatively higher than that of the soft pressure-sensitive adhesive (also referred to as “normal portion pressure-sensitive adhesive”) are die-coated and lightened. A method of producing the present pressure-sensitive adhesive sheet 10 can be mentioned by obtaining a curable pressure-sensitive adhesive sheet and further irradiating the photo-curable pressure-sensitive adhesive sheet with light to cure the pressure-sensitive adhesive sheet.

In the method for producing the present adhesive sheet 10, examples of the light to be irradiated include active energy rays such as ultraviolet rays, electron beams, visible rays, X-rays, and ion rays, which are appropriately selected according to the photopolymerization initiator used. It is preferable to do so. Among them, from the viewpoint of versatility, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable.

As the light source of ultraviolet rays, for example, a high-pressure mercury lamp, a metal halide lamp, a xenon arc lamp, a carbon arc lamp, or the like can be used.
Dose of ultraviolet light is preferably irradiated with ultraviolet light so that the integrated quantity of light wavelength 365nm is ^{1000mJ / cm 2 ~10000mJ / cm 2} , inter alia 1500 mJ / cm ² or more, or 6000 mJ / cm ² or less, 2000 mJ / cm ² among them It is particularly preferable to irradiate with ultraviolet rays so as to be equal to or more or 4000 mJ / cm ² or less.

<Manufacturing method of this adhesive sheet 20>
Next, an example of the method for manufacturing the adhesive sheet 20 will be described.
However, the manufacturing method of the present adhesive sheet 20 is not limited to the following manufacturing method example.

As an example of the method for producing the present adhesive sheet 20, a soft adhesive sheet which is a photocurable adhesive sheet and has a glass transition temperature of −50 ° C. to −20 ° C. and a photocurable adhesive sheet. The sheet surface of the photocurable curable pressure-sensitive adhesive sheet obtained by heat-sealing a normal portion pressure-sensitive adhesive sheet having a glass transition temperature relatively higher than that of the soft pressure-sensitive adhesive sheet is first irradiated with light. After partially curing the curable adhesive sheet,
Next, the sheet surface of the photocurable adhesive sheet is coated with a masking sheet having a size and shape that can shield light and match the shapes of the normal portion and the soft portion. A method of manufacturing the present pressure-sensitive adhesive sheet 20 can be mentioned by secondarily irradiating the surface coated with the masking sheet with light to partially cure the curable pressure-sensitive adhesive sheet.
The photocurable adhesive sheet will be described later.

Further, as another example of the method for producing the present adhesive sheet 20, a soft adhesive which is a photocurable adhesive and has a glass transition temperature of −50 ° C. to −20 ° C. and a photocurable adhesive. Light is first applied to the sheet surface of a photocurable curable pressure-sensitive adhesive sheet obtained by die-coating a normal portion pressure-sensitive adhesive which is a curable pressure-sensitive adhesive and has a glass transition temperature relatively higher than that of the soft pressure-sensitive adhesive. After irradiating to partially cure the curable adhesive sheet,
Next, the sheet surface of the photocurable adhesive sheet is coated with a masking sheet having a size and shape that can shield light and match the shapes of the normal portion and the soft portion. A method of manufacturing the present pressure-sensitive adhesive sheet 20 can be mentioned by secondarily irradiating the surface coated with the masking sheet with light to partially cure the curable pressure-sensitive adhesive sheet.
The term "matching" does not require strict identity, but means that the shape and size are substantially the same as those of the normal portion or the soft portion.

In the method for producing the present adhesive sheet 20, examples of the light to be primary and secondary irradiated include active energy rays such as ultraviolet rays, electron beams, visible rays, X-rays, and ion rays, and the photopolymerization started to be used. It is preferable to select an appropriate agent according to the agent. Among them, from the viewpoint of versatility, ultraviolet rays or electron beams are preferable, and ultraviolet rays are particularly preferable.
As the light source of ultraviolet rays, for example, a high-pressure mercury lamp, a metal halide lamp, a xenon arc lamp, a carbon arc lamp, or the like can be used.

The dose of ultraviolet rays at the primary irradiation is preferably irradiated with ultraviolet light so that the integrated quantity of light wavelength 365nm is ^{1000mJ / cm 2 ~10000mJ / cm 2} , inter alia 1500 mJ / cm ² or more, or 6000 mJ / cm ² or less, the Above all, it is particularly preferable to irradiate ultraviolet rays so as to be 2000 mJ / cm ² or more or 4000 mJ / cm ² or less.
The dose of ultraviolet rays at the secondary radiation is preferably ultraviolet irradiation so that the integrated quantity of light wavelength 365nm is ^{1000mJ / cm 2 ~10000mJ / cm 2} , inter alia 1500 mJ / cm ² or more, or 6000 mJ / cm ² or less, the Above all, it is particularly preferable to irradiate ultraviolet rays so as to be 2000 mJ / cm ² or more or 4000 mJ / cm ² or less.

<Photo-curable adhesive sheet>
Next, a curable pressure-sensitive adhesive sheet that can be suitably used in the methods for producing the present pressure-sensitive adhesive sheets 1, 10 and 20, that is, a photocurable curable pressure-sensitive adhesive sheet will be described.
However, the example described below is merely an example and is not limited to this.

The curable pressure-sensitive adhesive sheet has a gel fraction of less than 1%, particularly less than 0.8%, of which 0.5%, from the viewpoint that hot meltability can be exhibited in the state before photo-curing. It is particularly preferable that it is less than.
On the other hand, the gel fraction after photo-curing is preferably adjusted in the range of 40 to 100% from the viewpoint that high cohesive force can be obtained and foaming resistance in a moist heat environment can be obtained.
At this time, in order to adjust the gel fraction before photo-curing and the gel fraction after photo-curing as described above, the composition ratio of the cross-linking agent or the photopolymerization initiator may be adjusted in the composition or the manufacturing method, or during processing. The temperature and the amount of light irradiation may be adjusted. However, the method is not limited to this method.

(Curable adhesive sheet)
As an example of the curable pressure-sensitive adhesive sheet, a resin composition containing a (meth) acrylic copolymer, a cross-linking agent, and a photopolymerization initiator can be mentioned.
However, as described above, the composition of the pressure-sensitive adhesive composition for forming the present pressure-sensitive adhesive sheet is limited as long as the gel fraction after sticking can be made different depending on the portion in the pressure-sensitive adhesive sheet. is not.

(Adhesive composition)
As an example of the pressure-sensitive adhesive composition, a resin composition containing an acrylic copolymer, a cross-linking agent, and a photopolymerization initiator can be mentioned.

(Acrylic copolymer)
The acrylic copolymer as the base polymer contains a (meth) acrylic acid alkyl ester (a) having an alkyl group having 1 to 18 carbon atoms and an unsaturated monomer (b) copolymerizable therewith. Examples thereof include copolymers composed of monomer components.

Examples of the alkyl ester (a) include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, and hexyl (meth) acrylate. 2-Ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, Examples thereof include n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, and n-tetradecyl (meth) acrylate.

Examples of the monomer (b) include a carboxyl group-containing unsaturated monomer, a hydroxyl group-containing unsaturated monomer, an amide group-containing unsaturated monomer, an amino group-containing unsaturated monomer, and a glycidyl group-containing non-saturated monomer. Saturated monomer, cyano group-containing unsaturated monomer, maleimide group-containing monomer, itaconimide group-containing monomer, succinimide group-containing monomer, sulfonic acid group-containing unsaturated monomer, phosphate group-containing non-saturated monomer Examples thereof include functional group-containing unsaturated monomers such as saturated monomers.

In addition to the above, vinyl ester group-containing monomers such as vinyl acetate, aromatic unsaturated monomers such as styrene, (meth) acrylic acid cycloalkyl ester monomers such as isobornyl (meth) acrylate, and vinyl groups such as N-vinylpyrrolidone. Examples thereof include an alkoxy group-containing unsaturated monomer such as a containing heterocyclic compound and methoxyethyl (meth) acrylate.

Further, as an acrylic copolymer other than the above, a graft copolymer having a macromonomer as a branch component can also be used.

The stem component of the graft copolymer is preferably composed of a copolymer component containing a repeating unit derived from (meth) acrylic acid ester.
The glass transition temperature of the copolymer component constituting the stem component of the graft copolymer is the flexibility of the pressure-sensitive adhesive composition at room temperature and the wettability of the pressure-sensitive adhesive composition to an adherend, that is, adhesiveness. In order for the pressure-sensitive adhesive composition to obtain appropriate adhesiveness (tackiness) at room temperature, the glass transition temperature is preferably −70 ° C. to 0 ° C., particularly −65 ° C. or higher. Alternatively, it is particularly preferably −5 ° C. or lower, particularly −60 ° C. or higher or −10 ° C. or lower.
At this time, the glass transition temperature of the copolymer component constituting the stem component refers to the glass transition temperature of the polymer obtained by copolymerizing only the monomer component constituting the stem component of the graft copolymer.

On the other hand, it is preferable that the branch component of the graft copolymer contains a repeating unit derived from the macromonomer by introducing a macromonomer as the branch component of the graft copolymer.
The macromonomer is a polymer monomer having a polymerizable functional group at the terminal and a high molecular weight skeleton component.
The glass transition temperature (Tg) of the macromonomer is preferably higher than the glass transition temperature of the copolymer component constituting the graft copolymer. Specifically, it is preferably 30 ° C. to 120 ° C., more preferably 40 ° C. or higher or 110 ° C. or lower, and more preferably 50 ° C. or higher or 100 ° C. or lower.

(Crosslinking agent)
As the cross-linking agent, for example, a cross-linking agent having two or more cross-linking groups such as an epoxy group, an isocyanate group, an oxetane group, a silanol group, and a (meth) acryloyl group can be appropriately selected. Among them, polyfunctional (meth) acrylate having two or more (meth) acryloyl groups, especially three or more, and having an epoxy group, an isocyanate group, and a silanol group (meth) in terms of reactivity and the strength of the obtained cured product. ) Acrylate is preferred.

(Photopolymerization initiator)
The photopolymerization initiator functions as a reaction initiation aid in the cross-linking reaction of the cross-linking agent.
As the photopolymerization initiator, currently known ones can be appropriately used. Of these, a photopolymerization initiator that is sensitive to ultraviolet rays having a wavelength of 380 nm or less is preferable from the viewpoint of ease of controlling the crosslinking reaction. On the other hand, a photopolymerization initiator that is sensitive to light having a wavelength longer than 380 nm is preferable because the sensitive light easily reaches the deep part of the pressure-sensitive adhesive sheet.

Photopolymerization initiators are roughly classified into two types according to the radical generation mechanism: a cleavage-type photopolymerization initiator that can generate radicals by cleaving and decomposing a single bond of the photopolymerization initiator itself, and a photoexcited initiator. And the hydrogen donor in the system form an excitation complex, which is roughly classified into a hydrogen abstraction type photopolymerization initiator capable of transferring the hydrogen of the hydrogen donor.

Of these, the cleavage-type photopolymerization initiator decomposes to another compound when a radical is generated by light irradiation, and once excited, it loses its function as a reaction initiator. Therefore, it is preferable because it does not remain as an active species in the adhesive material after the cross-linking reaction is completed and there is no possibility of causing unexpected photodegradation of the adhesive material. On the other hand, the hydrogen abstraction type photopolymerization initiator does not generate decomposition products like the cleavage type photopolymerization initiator during the radical generation reaction by irradiation with active energy rays such as ultraviolet rays, so that it is unlikely to become a volatile component after the reaction is completed, and the subject is subject to It is useful in that it can reduce damage to the body.

Examples of the cleavage-type photoinitiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexylphenylketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-. On, 1- (4- (2-hydroxyethoxy) phenyl) -2-hydroxy-2-methyl-1-propane-1-one, 2-hirodoxy-1- [4- {4- (2-hydroxy-2) -Methyl-propionyl) benzyl} phenyl] -2-methyl-propane-1-one, oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone), phenylglycolic Methyl 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butane-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1-one On, 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone, bis (2,4,6-trimethylbenzoyl)- Examples thereof include phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, and derivatives thereof.

Examples of the hydrogen abstraction type photoinitiator include benzophenone, 4-methyl-benzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3'-dimethyl-4-methoxybenzophenone, 4- (meth). Acryloyloxybenzophenone, methyl 2-benzoylbenzoate, methyl benzoylate, bis (2-phenyl-2-oxoacetate) oxybisethylene 4- (1,3-acryloyl-1,4,7,10,13- Pentaoxotridecyl) Benzophenone, thioxanthone, 2-chlorothioxanthone, 3-methylthioxanthone, 2,4-dimethylthioxanthone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone and its derivatives And so on.
However, the photopolymerization initiator is not limited to the substances listed above. Any one of the cleavage-type photopolymerization initiator and the hydrogen-extracted photopolymerization initiator listed above may be used, or two or more of them may be used in combination.

(Other ingredients)
The pressure-sensitive adhesive composition may contain a known component blended in a normal pressure-sensitive adhesive composition as a component other than the above. For example, if necessary, a tackifier resin, an antioxidant, a light stabilizer, a metal inactivating agent, an antiaging agent, a hygroscopic agent, a polymerization inhibitor, an ultraviolet absorber, a rust preventive, and a silane coupling agent. , Various additives such as inorganic particles can be appropriately contained. Further, if necessary, a reaction catalyst (tertiary amine compound, quaternary ammonium compound, tin laurate compound, etc.) may be appropriately contained.

<Use of this adhesive sheet>
The present adhesive sheets 1, 10 and 20 (collectively referred to as "the present adhesive sheet") can be used as they are. It can also be used as follows.
However, the usage of this adhesive sheet is not limited.

(Adhesive sheet laminate)
The present adhesive sheet can be provided, for example, as an adhesive sheet laminate with a release film having a structure in which a release film is laminated on one side or both sides of the present adhesive sheet.

(Laminate for image display device configuration)
It is possible to produce and provide a laminated body for forming an image display device having a structure in which two constituent members for an image display device are laminated via the present adhesive sheet.

As the image display device component, for example, a laminate composed of any one or a combination of two or more of the group consisting of a touch panel, an image display panel, a surface protection panel, and a polarizing film can be exemplified.
However, it is not limited to these.

As an example of the laminate for configuring an image display device, in addition to the laminate composed of a protective panel / main adhesive sheet / polarizing film, for example, an image display panel / main adhesive sheet / touch panel, an image display panel / main adhesive sheet / protection. Examples of configurations such as panel, image display panel / main adhesive sheet / touch panel / main adhesive sheet / protective panel, polarizing film / main adhesive sheet / touch panel, polarizing film / main adhesive sheet / touch panel / main adhesive sheet / protective panel are given. Can be done. The protective panel and the image display panel may be those in which the touch panel sensor is incorporated in the protective panel or the image display panel itself.

(Image display device)
The image display device can also be configured by using the adhesive sheet or the above-mentioned laminated body for constructing the image display device. For example, an image display device having a structure in which the space between the two image display device components is filled with the present adhesive sheet can be mentioned.

Examples of the components for the two image display devices include personal computers, mobile terminals (PDAs), game consoles, televisions (TVs), car navigation systems, touch panels, pen tablets, and other components of image display devices such as LCDs, PDPs, and ELs. Can be mentioned. More specifically, for example, any one of the group consisting of a touch panel, an image display panel, a surface protection panel and a polarizing film, or a laminate composed of a combination of two or more kinds can be mentioned.

<Explanation of words>
Generally, a "sheet" is a thin product according to the definition in JIS, and its thickness is small and flat for its length and width. Generally, a "film" is thicker than its length and width. A thin flat product with an extremely small size and an arbitrarily limited maximum thickness, which is usually supplied in the form of a roll (Japanese Industrial Standard JIS K6900). However, since the boundary between the sheet and the film is not clear and it is not necessary to distinguish between the two in the present invention, the term "film" is used to include the "sheet" and is referred to as the "sheet" in the present invention. Even if it is, it shall include "film". Further, when the term "panel" is used, such as an image display panel, a protective panel, etc., it includes a plate body, a sheet and a film, or a laminate thereof.

In the present invention, when "X to Y" (X, Y are arbitrary numbers) is described, it means "X or more and Y or less" and "preferably larger than X" or "preferably Y", unless otherwise specified. It also includes the meaning of "smaller".
In addition, when "X or more" (X is an arbitrary number) is described, it includes the meaning of "preferably larger than X" and is described as "Y or less" (Y is an arbitrary number) unless otherwise specified. In the case of a field, unless otherwise specified, the meaning of "preferably smaller than Y" is included.

Claims (14)

When the sheet surface is viewed in a plan view, one or two hard portions exhibiting any shape selected from the group consisting of (a) frame shape, (b) island shape, (c) strip shape and (d) mesh shape. Have one or more in the seat surface
The hard portion includes a line to be cut (referred to as "planned cutting line") in the region, has a contour located 0.15 mm to 4 mm outside the planned cutting line, and has a contour. The adhesive sheet is characterized in that the gel fraction is 40 to 100% and the gel fraction is relatively larger than the portion other than the hard portion (referred to as "normal portion") in the sheet surface. .. The pressure-sensitive adhesive sheet according to claim 1, wherein the hard portion has a size that fits within a circle having a diameter of 0.3 mm to 20 mm, or has a narrowest width of 0.3 mm to 20 mm. .. When the seat surface is viewed in a plan view, one or two or more repeatedly bendable soft portions are provided in the seat surface, which are continuous between the upper and lower end edges and / or between the left and right edge edges.
The soft portion has a width of 1 mm to 30 mm, the glass transition temperature thereof is -50 ° C to -20 ° C, and a portion other than the soft portion in the sheet surface (referred to as "normal portion"). ) An adhesive sheet characterized by a relatively lower glass transition temperature. The pressure-sensitive adhesive sheet according to claim 3, wherein the ratio of the width of the soft portion to the thickness of the pressure-sensitive adhesive sheet is 50 to 1200. Having the hard part and the soft part in the sheet surface,
The hard portion has a gel fraction of 40 to 100%, and the gel fraction is relatively larger than that of the hard portion and the normal portion.
The pressure-sensitive adhesive sheet according to claim 3 or 4, wherein the soft portion has a glass transition temperature of −50 ° C. to −20 ° C., and the glass transition temperature is relatively lower than that of the normal portion. A pressure-sensitive adhesive sheet laminate with a release film, comprising a structure in which the pressure-sensitive adhesive sheet according to any one of claims 1 to 5 and a release film are laminated. An image display device configuration laminate having a structure in which image display device components are laminated on both sides of the adhesive sheet according to any one of claims 1 to 5. 7. The image display device component is a laminate composed of any one or a combination of two or more of the group consisting of a touch panel, an image display panel, a surface protection panel, and a polarizing film. The laminated body for configuring an image display device according to. An image display device configured by using the image display device configuration laminate according to claim 7 or 8. The method for manufacturing an adhesive sheet according to claim 1 or 2.
The hard portion has a size that allows the entire surface of the photocurable adhesive sheet to be covered with the sheet surface, can block light, and forms the hard portion. A method for producing an adhesive sheet, which comprises covering a masking sheet having a window portion having the same shape as the above, and then irradiating the surface coated with the masking sheet with light to partially cure the curable adhesive sheet. The method for manufacturing an adhesive sheet according to claim 3 or 4.
A photocurable adhesive sheet having a glass transition temperature of −50 ° C. to −20 ° C. (also referred to as “soft adhesive sheet”) and a photocurable adhesive sheet. The pressure-sensitive adhesive sheet is characterized in that a pressure-sensitive adhesive sheet having a glass transition temperature relatively higher than that of the soft pressure-sensitive adhesive sheet (also referred to as “normal portion pressure-sensitive adhesive sheet”) is heat-sealed and irradiated with light to be cured. Manufacturing method. The method for manufacturing an adhesive sheet according to claim 3 or 4.
A photocurable adhesive having a glass transition temperature of −50 ° C. to −20 ° C. (also referred to as “soft adhesive”) and a photocurable adhesive. Further, a pressure-sensitive adhesive having a glass transition temperature relatively higher than that of the soft pressure-sensitive adhesive (also referred to as "normal portion pressure-sensitive adhesive") is die-coated to obtain a photocurable pressure-sensitive adhesive sheet, which is further photo-curable. A method for producing an adhesive sheet, which comprises irradiating an adhesive sheet with light to cure it. The method for manufacturing an adhesive sheet according to claim 5.
A photocurable adhesive sheet having a glass transition temperature of −50 ° C. to −20 ° C. (also referred to as “soft adhesive sheet”) and a photocurable adhesive sheet. Further, on the sheet surface of the photocurable adhesive sheet obtained by heat-sealing an adhesive sheet having a glass transition temperature relatively higher than that of the soft adhesive sheet (also referred to as "normal portion adhesive sheet"), After primary irradiation with light to partially cure the curable pressure-sensitive adhesive sheet,
Next, the sheet surface of the photocurable adhesive sheet is coated with a masking sheet having a size and shape that can shield light and match the shapes of the normal portion and the soft portion. A method for producing an adhesive sheet, which comprises partially curing the curable adhesive sheet by secondarily irradiating a surface coated with the masking sheet with light. The method for manufacturing an adhesive sheet according to claim 5.
A photocurable adhesive having a glass transition temperature of −50 ° C. to −20 ° C. (also referred to as “soft adhesive”) and a photocurable adhesive. Light is applied to the sheet surface of the photocurable adhesive sheet obtained by die-coating with an adhesive having a glass transition temperature relatively higher than that of the soft adhesive (also referred to as "normal part adhesive"). After primary irradiation to partially cure the curable adhesive sheet,
Next, the sheet surface of the photocurable adhesive sheet is coated with a masking sheet having a size and shape that can shield light and match the shapes of the normal portion and the soft portion. A method for producing an adhesive sheet, which comprises partially curing the curable adhesive sheet by secondarily irradiating a surface coated with the masking sheet with light.

Images