TWI644794B - Method for manufacturing double-sided adhesive sheet for image display device - Google Patents

Abstract

The present invention provides a double-sided adhesive sheet for a novel image display device which can be bonded to an adherend surface without gaps and in a gap-like manner even when the adhered surface of the adhesive sheet has a step due to printing or the like.

The present invention relates to a method for manufacturing a double-sided adhesive sheet for an image display device, which is used for bonding double-sided adhesives of any two kinds of adherends selected from a surface protection panel, a touch panel and an image display panel. In the method for producing a sheet, and the double-sided adhesive sheet before bonding, an adhesive composition having a gel fraction of less than 40% is used, and the surface shape is the same as the uneven shape of the bonding surface of the adherend.

Description

Method for manufacturing double-sided adhesive sheet for image display device

The present invention relates to a double-sided adhesive sheet for an image display device for an image display device such as a liquid crystal display device (LCD), an organic EL (Electroluminescence) display device (OLED), and a plasma display device (PDP). And a method of manufacturing a double-sided adhesive sheet for an image display device with a release film. Further, the present invention relates to an image display device using the double-sided adhesive sheet for the image display device.

In recent years, the market for image display devices such as smart phones or tablets has been rapidly increasing, requiring design, fashion, and decoration, thickness reduction, weight reduction, and color diversification are progressing.

For example, in the surface protection panel of the image display device, a plexiglass, a plastic material such as an acrylic resin plate or a polycarbonate plate, or a back surface printing of a peripheral portion other than the opening surface of the surface protection panel is used, and the usual black color is used. Printing and white printing components.

Moreover, in the touch panel, a glass sensor and a plastic film sensor, or a single-touch (TOL) component that has been integrated with the surface protection panel using the touch panel function, or a touch is used. The control panel function has been integrated into the integrated or embedded components of the image display panel.

Then, the surface protection panel, the touch panel, and the image display panel (also referred to as "constituting members for image display devices") are combined to form an image display device of the touch panel type.

Moreover, in order to further enhance the visibility of the image, it is generally filled with a transparent resin. Each image display device has a structure that constitutes a gap between members.

For example, as a resin material for filling a void, a liquid adhesive, a thermoplastic adhesive sheet, an adhesive sheet, or the like is known.

In the case of a liquid adhesive, the resin can be freely flown into the gap to perform resin sealing. However, it is difficult to obtain the in-plane thickness accuracy in the visible opening surface portion, and when the ultraviolet irradiation is performed, the printed back of the protective panel is not irradiated. Ultraviolet rays, which may contaminate the electrode or wiring in an uncured state, and are concerned that the unhardened liquid resin may cause a solvent crack in the plastic component inside the image display device over time, or in the hardened portion, due to hardening Peeling between components caused by shrinkage.

Further, in the case of the thermoplastic film, the related sheet can be heat-melted and sealed, but there is a concern that the resin overflows during heating and melting or residual stress due to poor expansion of the heating wire or warpage. The problem of temperature management during storage and transportation is caused by time-lapse peeling, a decrease in the production time due to the heating process, or a material which melts at a low temperature.

In this respect, in the case of adhering the sheet, the relevant sheet can be easily laminated at normal temperature and the in-plane dimensional accuracy is also very good, and the production time is also short, so that the mass productivity is excellent.

Patent Literatures 1 and 2 disclose an adhesive sheet in which each image display device is bonded to a constituent member.

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open Publication No. 2003-238915

Patent Document 2: Japanese Patent Laid-Open Publication No. 2004-231723

In recent years, as the color of the image display panel is diversified, the back side is printed in black. White is appearing outside. In the case of black, the thickness of the back side printing is about 5 to 20 μm, but in the case of white, in order to conceal the light leakage from the image display panel, the printing thickness needs to be about 40 to 80 μm.

However, the liquid adhesive or the thermoplastic adhesive sheet is completely a flowing resin. On the other hand, although the adhesive sheet flows slightly, the resin sealing is not complete when the surface of the adherend has a large unevenness.

For example, as shown in FIG. 11, when the printing 14 of white or the like is applied to the peripheral portion of the surface protection panel 11, a step is generated. In such a case, when the surface protection panel 11 and the touch panel 12 are bonded via the adhesive sheet 13, as shown in FIG. 12, there are cases where the inner corners of the printing 14 and the viewing opening surface 15 are When the void 16 is generated, the visibility is deteriorated or foaming or peeling due to a sudden temperature change occurs. Therefore, in order to overlap the adhesive sheet 13 without a gap, the adhesive sheet 13 is required to follow the step difference caused by the printing 14 to fill the step followability of each corner.

In order to impart such step followability, it is considered to design the double-sided adhesive sheet to be relatively soft. However, if exposed to a high temperature and high humidity environment or exposed to an imminent temperature change, the double-sided adhesive sheet may have a problem of foaming or peeling at the bonding interface.

On the other hand, in order to solve the problem of such foaming and peeling, it is considered to design the double-sided adhesive sheet to be relatively hard and have a high cohesive force. However, in the case of such a design, the double-sided adhesive sheet has a possibility that the result step followability is poor.

Therefore, an object of the present invention is to provide a new image in which an adherend surface of an adherend to which an adhesive sheet is bonded, even if there is a step caused by printing or the like, and which can be adhered to the adhered surface without a gap and in a close contact manner. The display device uses a double-sided adhesive sheet.

The present inventors have assumed that there is a limit to the step followability and the foaming resistance by the material design of the double-sided adhesive sheet, and after repeated efforts, it was found that the double-sided adhesive sheet itself was adhered and adhered in advance. The way in which the concave and convex shapes of the body fit surface are the same The present invention can be accomplished by performing a forming process so as to be superposed on the surface of the associated adherend without a gap.

That is, the present invention is a method for manufacturing a double-sided adhesive sheet for an image display device, which is characterized in that it is used to perform any two kinds of adherends selected from the group consisting of a surface protection panel, a touch panel, and an image display panel. A method for manufacturing a double-sided adhesive sheet, and a double-sided adhesive sheet before bonding, using an adhesive composition having a gel fraction of less than 40%, and forming a concave-convex shape of a bonding surface with the above-mentioned adherend The same face shape.

In this case, after the adhesive sheet is formed using the adhesive composition having a gel fraction of less than 40%, the adhesive sheet is shaped to have the same surface shape as that of the bonded surface of the adherend, and The above shaping can be performed while making an adhesive sheet.

The adhesive surface of the double-sided adhesive sheet for the image display device manufactured by the manufacturing method of the present invention has the same surface shape as the concave-convex shape of the bonding surface of the adherend, and is bonded to the adherend. Even if there is a step caused by printing or the like, it can be adhered to the surface to be adhered without any gap.

1‧‧‧Double-sided adhesive sheets for image devices

1a‧‧‧Fitting surface

1b‧‧‧ convex

2‧‧‧Surface protection panel

2a‧‧‧adhesive

2b‧‧‧Steps Department

2c‧‧‧View open face

2d‧‧‧ surface

2e‧‧‧ inner circumference

3‧‧‧Touch panel

3a‧‧‧electrode pattern

4‧‧‧Image display panel

4a‧‧ ‧ step department

5‧‧‧Border components

6‧‧‧cutting section

7‧‧‧electrode terminal

8‧‧‧ recess

9a~9c‧‧‧ release film

10‧‧‧ Guidance Department

11‧‧‧Surface protection panel

12‧‧‧Touch panel

13‧‧‧Adhesive sheets

14‧‧‧Printing

15‧‧‧View open face

16‧‧‧ gap

21‧‧‧Evaluation shaping mold

22‧‧‧Adhesive film

23‧‧‧ glass plate

24‧‧‧White printing

25‧‧‧Adhesive tablets

26‧‧‧Polar plate

Fig. 1 is a schematic exploded perspective view showing an example of a case where a surface protection panel and a touch panel are bonded together by using a double-sided adhesive sheet according to an embodiment of the present invention.

Fig. 2 is a cross-sectional view showing an example of a state before the surface protection panel and the touch panel are bonded together by using the double-sided adhesive sheet of the embodiment shown in Fig. 1.

3 is a cross-sectional view showing an example of a state in which a surface protection panel and a touch panel are bonded together by using a double-sided adhesive sheet of the embodiment shown in FIG. 1.

Fig. 4 is a cross-sectional view showing an example in which an image display panel is provided with a frame member.

Fig. 5 is a perspective view showing an example of a case where a double-sided adhesive sheet of the form shown in Fig. 1 is provided with a notched portion.

6 is a cross-sectional view showing an example in which the electrode member is housed in the notch portion and the surface protection panel and the touch panel are bonded to each other by using the double-sided adhesive sheet of the embodiment shown in FIG. 5 .

Fig. 7 is a partially enlarged perspective view showing an example of a case where a double-sided adhesive sheet of the form shown in Fig. 1 is provided with a concave portion.

Fig. 8 is a cross-sectional view showing an example of a case where a release film is laminated on both sides of the double-sided adhesive sheet of the embodiment shown in Fig. 1.

Fig. 9 is a cross-sectional view showing an example of a case where a release film is laminated on both sides of the double-sided adhesive sheet of the embodiment shown in Fig. 1.

Fig. 10 is a cross-sectional view showing an example of a case where a release film is laminated on both sides of the double-sided adhesive sheet of the embodiment shown in Fig. 1.

Fig. 11 is a cross-sectional view showing an example of a state before the surface protection panel and the touch panel are bonded together using the previous adhesive sheet.

Fig. 12 is a cross-sectional view showing an example of a state in which a surface protection panel and a touch panel are bonded together by using an adhesive sheet of the embodiment shown in Fig. 11 .

Fig. 13 is a view for explaining a forming method in an adhesive sheet forming treatment test.

Fig. 14 is a view showing a test method in a printing step followability test.

Hereinafter, an example of an embodiment of the present invention will be described. However, the present invention is not limited by the following embodiments.

The double-sided adhesive sheet 1 (also referred to as "double-sided adhesive sheet 1") for an image display device according to an embodiment of the present invention is shown in FIGS. 1 to 3 for use in protecting the surface protection panel 2 The control panel 3 is attached to a rectangular shaped adhesive sheet in plan view.

The surface protection panel 2 has a step portion 2b on the adhered surface 2a to which the double-sided adhesive sheet 1 is adhered.

The double-sided adhesive sheet 1 is formed by bonding the surface shape of the bonding surface 1a of the adherend surface 2a to the same surface shape as that of the surface to be adhered 2a.

The image display device includes a smart phone, a tablet, a mobile phone, and a battery including a liquid crystal display device (LCD), an organic EL display device (OLED), and a plasma display device (PDP). Video, game consoles, personal computers, car navigation systems, ATM (Automatic Teller Machine), fish detectors, etc.

The double-sided adhesive sheet 1 can be used for bonding the surface protection panel 2 and the touch panel 3. However, the use of the double-sided adhesive sheet 1 is not limited thereto, and it can be used for laminating any two kinds of adherends of the constituent members of the image display device selected from the surface protective panel, the touch panel, and the image display panel. In particular, it is preferably used for bonding a surface protection panel to a touch panel or a touch panel to an image display panel.

Further, the surface protection panel may be formed of a reinforced glass, a plastic material such as an acrylic resin plate or a polycarbonate plate, or the like. Moreover, the touch panel may be formed by a glass sensor or a plastic film sensor, a touch panel function integrated into an integrated or embedded component of the image display panel.

The adhered surface 2a of the surface protective panel 2 to which the double-sided adhesive sheet 1 is adhered has an uneven shape as shown in Fig. 1 or Fig. 2 . In other words, the step portion 2b is formed by printing white or black on the peripheral portion of the back surface of the surface protection panel 2, for example, and the peripheral portion of the adherend surface 2a is formed so as to protrude first. In other words, the adhered surface 2a of the surface protective panel 2 is formed in a cross-sectional concave shape having a rectangular concave concave viewing surface 2c in the vicinity of the center.

The height of the step portion 2b is not limited. For example, it may be formed to be 1 μm or more and 100 μm or less from the viewing opening surface 2c. Among them, it is preferably formed to be 5 μm or more or 90 μm or less.

The step portion 2b can be formed by printing or can be formed by other methods. For example, as shown in FIG. 4, the frame member 5 is provided in the peripheral portion of the image display panel 4 to form the step portion 4a.

Further, the step portion 2b is formed in a first-order shape, but the present invention is not limited thereto. For example, the step portion 2b may be formed in a plurality of steps such as a second-order shape or a third-order shape.

In the present embodiment, the surface 2d of the step portion 2b is formed in a planar shape. However, the present invention is not limited thereto, and may be, for example, a shape such as an inclined shape, a curved convex shape, or a curved concave shape.

In particular, according to the image display device, the electrodes of the respective members are disposed in the step portion 2b or When the cable is chamfered or the design of the opening surface 2c is designed, the shape may not be a straight line and may be curved.

The inner peripheral surface 2e of the step portion 2b is formed substantially perpendicularly to the viewing opening surface 2c, but is not limited thereto. For example, the angle of the inner peripheral surface 2e is preferably 0° or more and less than 180° with respect to the visual opening surface 2c, and more preferably 60° or more or 90° or less.

The inner peripheral surface 2d may be formed in a step shape, an arc shape, a curved shape, or the like.

The double-sided adhesive sheet 1 is preferably at least one side surface, that is, a bonding surface 1a adhered to the adhered surface 2a of the surface protection panel 2, and the concave-convex shape of the bonding surface of the adherend is shaped, that is, adhered The surface of the surface 2a has the same shape. In other words, it is preferable to form a substantially rectangular convex portion 1b which is raised first in the vicinity of the center of the bonding surface 1a, and is formed in a cross-sectional convex shape.

Further, in the present invention, the at least one side surface of the double-sided adhesive sheet is shaped to have the same surface shape as the uneven surface of the bonded surface of the adherend, in other words, to form a conformal according to the above-mentioned adherend. The convex-concave shape of the uneven shape of the surface, in other words, means that the uneven shape is formed such that at least one side surface of the double-sided adhesive sheet overlaps with the bonded surface of the adherend.

For example, a concave portion corresponding to the convex portion of the bonding surface of the adherend and which is engageable with the convex portion of the double-sided adhesive sheet is preferably formed on the bonding surface of the double-sided adhesive sheet. a convex portion corresponding to the concave portion of the bonding surface of the adherend and engageable with the concave portion.

Since the bonding surface 1a of the double-sided adhesive sheet 1 is formed in the same shape as the surface of the adherend surface 2a in this manner, when the double-sided adhesive sheet 1 is attached to the surface protective panel 2, as shown in FIG. As shown in the above, the bonding surface 1a can be bonded to the surface to be adhered 2a without a gap, and the bonding surface can be bonded without a gap, and deterioration in visibility, peeling, foaming, and the like can be prevented.

The double-sided adhesive sheet 1 is bonded to the bonding surface 1a of the adherend surface 2a of the surface protection panel 2 at least on one side surface, and is formed in a concavo-convex shape of the bonding surface of the adherend. One of the shapes is a surface shape in which one of the surface shapes of the adhesive surface 2a is the same, and it is not necessary to form the same surface shape as the concave-convex shape of the bonding surface of the adherend.

The uneven shape of the bonding surface 1a is preferably formed into a surface shape having the same shape as that of the surface to be adhered 2a, and is bonded to each other without a gap. Among them, the double-sided adhesive sheet 1 which is shaped like the surface shape of the surface to be adhered 2a has a certain fluidity before curing, so that it is a certain degree of error, that is, the length of each part (each part) Errors of -5% or more and +5% or less of height, width, or width), especially errors of -1% or more or +1% or less, are tolerable. For example, the height of the convex portion 1b of the double-sided adhesive sheet 1 can be tolerated, especially if it is -1% or more, as long as it is -5% or more and +5% or less with respect to the step portion 2b of the surface protection panel 2. An error of +1% or less is more acceptable. Further, for example, the lateral width of the convex portion 1b of the double-sided adhesive sheet 1 is allowed to be 0.95 times or more and 1.05 times or less with respect to the lateral width of the visible opening surface 2c of the surface protection panel 2, and it is acceptable to be 0.99 times or more. Or 1.01 times or less, it is more acceptable. In other words, as long as the size is an error of -5% or more and +5% or less, it is acceptable, and if it is an error of -1% or more or +1% or less, it is more acceptable.

Further, the maximum thickness of the double-sided adhesive sheet 1 is preferably 1.0 times or more and 3.0 times or less with respect to the height of the step portion 2b, and more preferably 1.1 times or more and 2.0 times or less.

Further, the double-sided adhesive sheet 1 is subjected to shaping processing only on one side (the surface protective panel 2 side). Further, the both sides of the double-sided adhesive sheet 1 may be respectively formed into the same shape as the uneven shape of the bonded surface of the adhered adherend. For example, when the adhered surface of the touch panel 3 has a step portion, the forming process may be performed on both sides.

As shown in FIG. 5 or FIG. 6, the double-sided adhesive sheet 1 may be provided with a notch portion 6 for accommodating the electrode terminal 7 connected to the electrode pattern 3a on the touch panel 3 at the peripheral portion.

The notch portion 6 can be formed, for example, by cutting a vicinity of the center of one edge portion of the double-sided adhesive sheet 1 into a rectangular shape.

Further, as shown in Fig. 7, the concave portion 8 in which the double-sided adhesive sheet 1 is recessed may be used.

The recess 8 is the same as the notch 6 and can accommodate the electrode terminal 7. The notch portion 6 or the recess portion 8 can be formed by cutting with a Tomson knife or by pressing of a stamping die or the like.

<Material of double-sided adhesive sheet 1>

As the material of the double-sided adhesive sheet 1, a previously known adhesive sheet material can be used. For example, 1) a (meth)acrylate-based polymer (in the meaning of a copolymer, hereinafter referred to as "acrylate-based (co)polymer)") is used as a base resin, and a crosslinking monomer is blended therein. If necessary, a crosslinking initiator or a reaction catalyst is used to form a crosslinking reaction, or 2) a butadiene or an isoprene copolymer is used as a base resin, and a crosslinking list is prepared therein. a cross-linking initiator or a reaction catalyst as needed, which is formed by crosslinking reaction, or 3) using a polyfluorene-based polymer as a base resin, and blending a crosslinking monomer thereto A cross-linking initiator or a reaction catalyst or the like is required to form a cross-linking reaction, or 4) a polyurethane-based adhesive using a polyurethane-based polymer as a base resin. .

In the present invention, the physical properties of the adhesive sheet itself are not essential, but the acrylate-based (co)polymer of the above 1) can be preferably used from the viewpoints of adhesion, transparency, weather resistance and the like.

When a property such as electrical characteristics or a low refractive index is required, the butadiene or isoprene copolymer of the above 2) can be preferably used.

In the case where heat resistance, rubber elasticity or the like in a wide temperature range is required, the polyoxynphthoxy copolymer of the above 3) can be preferably used.

When a property such as re-peelability is required, the polyurethane-based polymer of the above 4) can be preferably used.

The acrylate polymer (including the copolymer) can be appropriately adjusted in terms of the glass transition temperature (Tg), etc. by the type, composition ratio, polymerization conditions, and the like of the acrylic monomer or methacrylic monomer used for the polymerization. characteristic.

As an acrylic monomer used to polymerize an acrylate polymer or Examples of the methacrylic acid monomer include 2-ethylhexyl acrylate, n-octyl acrylate, n-butyl acrylate, ethyl acrylate, and methyl methacrylate. It is also possible to use vinyl acetate, hydroxyethyl acrylate, acrylic acid, glycidyl acrylate, acrylamide, acrylonitrile, methacrylonitrile, fluoroacrylate, which are obtained by copolymerizing a hydrophilic group or an organic functional group. , polyoxy acrylate, and the like.

Among the acrylate polymers, a (meth)acrylic acid alkyl ester copolymer is particularly preferred.

As the (meth) acrylate used for forming the alkyl (meth) acrylate copolymer, that is, an alkyl acrylate or an alkyl methacrylate component, the alkyl group is preferably an n-octyl group or an isooctyl group. One or a selected from the group consisting of an alkyl acrylate or an alkyl methacrylate of any one of 2-ethylhexyl, n-butyl, isobutyl, methyl, ethyl or isopropyl A mixture of two or more kinds.

An acrylate or methacrylate having an organic functional group such as a carboxyl group, a hydroxyl group or a glycidyl group as another component can be copolymerized. Specifically, a monomer component obtained by appropriately combining the alkyl (meth) acrylate component and the (meth) acrylate component having an organic functional group as a starting material can be obtained by heat polymerization ( Methyl) acrylate copolymer polymer.

In particular, one type of alkyl acrylate such as isooctyl acrylate, n-octyl acrylate, n-butyl acrylate or 2-ethylhexyl acrylate may be used, or a mixture of two or more kinds selected from the group consisting of Or at least one or more of isooctyl acrylate, n-octyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and the like may be copolymerized with acrylic acid.

As the polymerization treatment using the monomers, a known polymerization method such as solution polymerization, emulsion polymerization, bulk polymerization, or suspension polymerization may be employed. In this case, a thermal polymerization initiator or a photopolymerization initiator may be used depending on the polymerization method. The polymerization initiator is added, whereby an acrylate copolymer is obtained.

As a more preferable example of the adhesive composition, a monomer having a glass transition temperature (Tg) of less than 0 ° C and a glass transition temperature (Tg) of 0 ° C or more and less than 80 ° C may be mentioned. A2 and a monomer having a glass transition temperature (Tg) of 80 ° C or higher and a copolymer of a1: a2: a3 = 10 to 40: 90 to 35: 0 to 25 molar ratio containing a weight average molecular weight of 50000~ An adhesive composition of a (meth)acrylic copolymer of 400000 (meth) acrylate copolymer, a crosslinking agent, and a photopolymerization initiator.

When the adhesive sheet is prepared by using the related adhesive composition, it can be kept in a sheet form at room temperature and exhibits self-adhesiveness. If heated in an uncrosslinked state, it has melting or flowing hot melt property, and further It is photohardened and exhibits excellent cohesive force after photohardening.

Further, as another example of a more preferable adhesive composition, an adhesive composition containing an acrylic copolymer, a crosslinking agent, and a photopolymerization initiator containing a graft copolymer having a macromonomer as a branch component may be mentioned. Things.

The adhesive sheet can be used to form an adhesive sheet, and can be kept in a sheet form at room temperature and exhibit self-adhesiveness. If heated in an uncrosslinked state, it has melting or flowing hot melt, and further light can be performed. It hardens and exhibits excellent cohesion after light hardening.

In this case, the main component of the acrylic copolymer preferably contains a copolymer component containing a repeating unit derived from (meth) acrylate, and the glass transition temperature of the copolymer constituting the main component is preferably -70 to 0. °C, especially -65 ° C or more or -5 ° C or less, and particularly preferably -60 ° C or more or -10 ° C or less.

The macromonomer is a polymer monomer having a terminal polymerizable functional group and a high molecular weight skeleton component.

On the other hand, the glass transition temperature (Tg) of the macromonomer of the acrylic copolymer is preferably higher than the glass transition temperature of the copolymer component constituting the acrylic copolymer, and particularly preferably 30 ° C to 120 ° C. It is particularly preferably 40 ° C or more or 110 ° C or less, and more preferably 50 ° C or more or 100 ° C or less.

Further, the high molecular weight skeleton component of the macromonomer preferably contains an acrylic polymer or a vinyl polymer. For example, polystyrene, copolymer of styrene and acrylonitrile, poly(t-butyl styrene), poly(α-methylstyrene), polyvinyltoluene, polymethyl Methyl acrylate and the like.

As the crosslinking monomer (also referred to as "crosslinking agent") used for crosslinking the acrylate polymer, a polyfunctional (meth) acrylate having two or more (meth) acrylonitrile groups can be used. a polyfunctional organofunctional resin having two or more organic functional groups such as an isocyanate group, an epoxy group, a melamine group, a diol group, a decyloxy group or an amine group, and a metal having zinc, aluminum, sodium, zirconium, calcium, or the like The organometallic compound of the complex.

Examples of the above polyfunctional (meth) acrylate include 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, and 1,9-nonanediol diacrylic acid. Ester, trimethylolpropane triacrylate, and the like.

The content of the crosslinking monomer may be adjusted in combination with other factors in such a manner that the desired physical properties can be obtained. Generally, it may be 0.01 to 40.0 parts by mass, preferably 0.1 to 100 parts by mass based on the base polymer. The adjustment is carried out within a range of 30.0 parts by mass, particularly 0.5 to 30.0 parts by mass. However, in the balance with other factors, this range can also be exceeded.

Further, when the acrylate polymer is crosslinked, a crosslinking initiator (peroxidation initiator, photopolymerization initiator) or a reaction catalyst (a tertiary amine compound or a quaternary ammonium compound) is appropriately added. , tin laurate compound, etc.), is effective.

When the adhesive composition for forming the double-sided adhesive sheet 1 is subjected to ultraviolet irradiation crosslinking, it is preferred to use a photocurable adhesive composition. Therefore, it is preferred to contain a photopolymerization initiator, if necessary, a crosslinking agent in addition to a base resin such as an acrylate polymer.

As the photopolymerization initiator, either a cleavage type photoinitiator or a hydrogen absorbing photoinitiator can be used, or both can be used in combination.

Examples of the cleavage type photoinitiator include benzoin butyl ether, benzoin dimethyl ketal, and hydroxyacetophenone.

On the other hand, examples of the hydrogen absorbing type photoinitiator include benzophenone and rice. Its ketone, dibenzocycloheptanone, 2-ethyl hydrazine, isobutyl thioxanthone and the like.

However, it is not limited to the above-mentioned substances.

The amount of the photopolymerization initiator to be added may be adjusted so that the storage shear modulus is within a specific range, and generally 0.05 to 5.0 parts by mass based on 100 parts by mass of the base polymer. The photopolymerization initiator can be used in combination with the hydrogen absorption type and the cleavage type in a ratio of 1:1. However, it is also possible to exceed this range in balance with other elements.

In addition to the above ingredients, pigments such as pigments or dyes having near-infrared absorbing properties, adhesion-imparting agents, antioxidants, anti-aging agents, hygroscopic agents, ultraviolet absorbers, decane coupling agents, natural substances or synthetic may be appropriately formulated as needed. Various additives such as resin, glass fiber or glass beads.

Regarding the double-sided adhesive sheet before the lamination, the gel fraction of the adhesive composition before the shaping is preferably less than 40%, more preferably 20% or less. Since the gel fraction of the adhesive composition is set to less than 40%, the bonding of the molecular chains constituting the adhesive composition to each other is suppressed to an appropriate range, and thus, when the forming treatment is performed by press treatment or the like It is easy to form the same surface shape as the uneven shape of the bonding surface of the adherend.

Various methods can be used to adjust the gel fraction. For example, in the case of thermal crosslinking, the gel fraction can be increased by heating the adhesive sheet. At this time, the gel fraction can be adjusted by changing the temperature or time during heating or heating and drying.

Further, in the case where the ultraviolet rays are crosslinked, the gel fraction can be increased by irradiating the adhesive sheet with ultraviolet rays.

For example, the gel fraction can be adjusted by changing the amount of ultraviolet irradiation. In this case, the amount of ultraviolet rays to be irradiated is preferably 10,000 mJ/cm ² or less, more preferably 1,500 mJ/cm ² or less, and still more preferably 1,000 mJ/cm ² or less.

The double-sided adhesive sheet 1 may be subjected to a step of forming the adhesive composition into a sheet shape (also referred to as a "sheet forming step"), and forming at least one side of the double-sided adhesive sheet with the above-mentioned It is manufactured by the step (also referred to as "forming step") of the surface shape of the adhesive surface of the adhesive body having the same uneven shape.

The order of the sheet forming step and the forming step may be arbitrary or may be performed simultaneously.

<Sheet Forming Step>

The above adhesive composition is preferably formed into a sheet form using an adhesive composition having a gel fraction of less than 40%.

The double-sided adhesive sheet 1 can be formed by a single material or a plurality of layers of two or three layers.

In order to make the operation easy and the like, the double-sided adhesive sheet 1 can be released from the film on one side or two areas. As the release film, a material which has existed before can be used, and for example, a PET (polyethylene terephthalate) film or the like can be used.

The release film is preferably laminated on the double-sided adhesive sheet 1 as follows, for example.

As shown in FIG. 8, the peripheral edge portion of the release film 9a is laminated on the both sides of the double-sided adhesive sheet 1 so that the peripheral edge portion of the double-sided adhesive sheet 1 protrudes outward. Thereby, it becomes difficult to directly contact the double-sided adhesive sheet 1, and the bonding industry becomes easy. The peripheral edge portion of the release film 9a on at least one side may be laminated so as to protrude outward from the peripheral edge portion of the double-sided adhesive sheet 1.

Further, as shown in Fig. 9, the release film 9b is laminated on both sides of the double-sided adhesive sheet 1, and the release film 9b on one side is formed to have the same surface shape as the surface of the bonding surface 1a. The shape is adhered to the bonding surface 1a to form a layer. Thereby, the double-sided adhesive sheet 1 becomes easy to conform. When the forming process is applied to both sides of the double-sided adhesive sheet, the release film on both sides can be shaped.

Further, as shown in FIG. 10, the release film 9c may be laminated on both sides of the double-sided adhesive sheet 1, and the peripheral edge portion of the release film 9c may protrude outward from the peripheral edge portion of the double-sided adhesive sheet 1. The method is laminated, and is provided in one part or the whole circumference of the peripheral portion of the release film 9c. The guide portion 10 between the release films 9c to prevent stress on the double-sided adhesive sheet 1 is prevented. Thereby, deformation of the double-sided adhesive sheet 1 can be prevented.

The guide portion 10 can be formed by placing various film pieces at specific positions. For example, a double-sided adhesive sheet having a double-sided adhesive sheet 1 sandwiched by a release film and cut into a specific size is attached, and then any release film is peeled off to be double-sidedly adhered. In a state where one of the sheets 1 is exposed, a film piece is provided at a specific position (for example, a facing edge portion) of the release film which protrudes outward from the peripheral edge portion of the double-sided adhesive sheet 1.

Then, by bonding the release film to the exposed adhesive surface of the double-sided adhesive sheet 1, a double-sided adhesive sheet having the guide portion 10 can be formed.

At this time, the material of the film piece is not particularly limited. For example, various polyolefin resins such as polypropylene and polyethylene; various polyester resins such as polylactic acid and polyethylene terephthalate; and various polyamine resins such as nylon and 12-nylon. Among them, a film containing polyethylene terephthalate is preferable in terms of easiness, heat resistance, strength, and the like. Further, the guide portion 10 is preferably coated with a material such as an adhesive composition or a film adhered to the release film on one or both sides so as not to move from any position on the release film.

Further, the guide portion 10 does not have to be composed of a single film, and a laminated film composed of a plurality of sheets can be produced. In this case, it is not necessary for all of the laminated films to have the same shape, and the films of different shapes may be overlapped to give specific functions.

Moreover, it is preferable that the guide portion 10 is provided at least at the opposite edge portion. The height of the guide portion 10 is not particularly limited, and is preferably 0.5 times or more and 2.0 times or less with respect to the maximum thickness of the double-sided adhesive sheet 1, and more preferably 1.0 times or more and 1.5 times or less.

In addition, as a release film used for pressing the planar adhesive sheet having a release film described later via a release film, it is preferred to use a non-stretch film. When the shaping treatment is performed by a press treatment or the like by using a non-stretched film, it is possible to have an effect of easily forming a surface shape similar to the original uneven shape.

The above-mentioned non-stretching film, especially the mechanical strength, softness and chemical resistance of the film itself From the viewpoint of the above, it is more preferred to use either an unstretched polypropylene film, an unstretched polyethylene film, or an unstretched polyester film.

<Shaping step>

The double-sided adhesive sheet 1 can be produced, for example, by forming a stamping frame, shaping using a mold, forming by a roll, forming by lamination, or the like. Among them, it is preferable from the viewpoints of the shape of the stamping frame, the productivity, the precision of the forming process, and the like.

By forming the stamping frame, the planar adhesive sheet having the release film can be pressed through the release film or the adhesive sheet can be directly pressed to form the shaped double-sided adhesive sheet 1. More specifically, a mold that mimics the shape of the adherend is directly pressed against at least one side surface of the double-sided adhesive sheet to form a shape, or a mold that mimics the shape of the adherend is pressed against the release film. A method of forming a shape on at least one side of a double-sided adhesive sheet.

In this case, the mold that mimics the shape of the adherend means that the bonding surface 1a of the adhesive sheet 1 can be formed into a mold having a concave-convex shape that can be fitted to the uneven shape of the bonding surface of the adherend, in other words, And means a mold having a cavity having the same shape as the uneven shape of the bonding surface of the adherend.

Further, the formed double-sided adhesive sheet 1 can be produced by pressing a release film by a press mold to form a shape, and applying or flowing an adhesive composition or the like to the release film.

The forming of the mold can be carried out by forming the adhesive composition into a mold frame and solidifying it, thereby producing a shaped double-sided adhesive sheet 1.

By forming the roll, the formed double-sided adhesive sheet 1 can be produced by passing a flat adhesive sheet having a release film through the rolls.

The formed double-sided adhesive sheet 1 can be produced by forming two sheets of planar adhesive sheets of different sizes and overlapping them by lamination.

In the double-sided adhesive sheet 1, since the surface shape of the bonding surface 1a is shaped to have the same surface shape as that of the surface to be adhered 2a, even if the step surface 2b due to printing or the like is applied to the adherend surface 2a, The constituent members for each image display device such as the surface protection panel 2 or the touch panel 3 can be bonded without a gap.

Hereinafter, an example of the method of producing the double-sided adhesive sheet 1, in particular, the method of forming the surface shape of the bonding surface of the double-sided adhesive sheet will be further specifically described.

(Formation method by stamping die) a) Method of pressing through a release film

The original sheet of the flat adhesive sheet having the release film of the two-area layer is appropriately cut into a long strip, and the adhesive sheet of the cut strip is successively fed out, and the surface shape of the adhered surface 2a according to the surface of the adherend is used. The stamping frame is formed by heat-pressing a flat adhesive sheet via a release film. At this time, the stamping die according to the surface shape of the adhesive surface 2a may be pressed against at least one side surface of the double-sided adhesive sheet via the release film.

Further, the above-mentioned cut-and-raised strip means a reel which is formed by inserting a knife from a wide-film roll of a wide film and forming a narrow film.

In the next step, the release film on one side is peeled off, and the exposed adhesive sheet is cut according to the shape of the shaped shape, and the useless adhesive edge outside the outer shape is erased, and the re-attachment is wider than the outer cut size. New release film.

Further, in the next step, the sheet is cut into an operable shape, and the double-sided adhesive sheet 1 is produced.

b) Method of directly pressing the adhesive sheet

The original sheet of the flat adhesive sheet having the two-layered release film is appropriately cut into a long strip, and the adhesive sheet of the cut strip is successively fed out, and the release film on one side is peeled off, and the surface is adhered according to the surface of the adherend. The shape is a stamping die that is adhered to the surface shape of the face 2a, and the surface is shaped by directly pressing the flat adhesive sheet. At this time, the stamping frame according to the surface shape of the adhering surface 2a is directly pressed against at least one side surface of the double-sided adhesive sheet.

In the next step, the adhesive sheet on the exposed side is cut in accordance with the shape of the shaped shape, and the useless adhesive edge outside the outer shape is erased, and the new release film wider than the outer cut size is reattached.

Further, in the next step, the sheet is cut into an operable shape, and the double-sided adhesive sheet 1 is produced.

The material of the stamping frame is not particularly limited. For example, a polyoxymethylene resin or a fluorine-based resin excellent in mold release property can also be used. Further, even if it is a material having no mold release property such as stainless steel or aluminum, it can be preferably used by applying various release agents.

The temperature of the hot press is, for example, room temperature or higher, preferably 80 ° C or higher, more preferably 100 ° C or higher. Further, the pressing pressure, the pressing depth, and the pressing time may be appropriately adjusted according to the size, the shape, and the shaping state.

Further, examples of the cutting method include a cutting method by a Tomson knife or a rotary knife.

Further, there is also a method of performing surface forming and shape cutting by respective processes as described above. For example, if a mold obtained by integrating a mold for forming a shape with a cutting die is used, the surface can be added in one step. Shape and shape cutting.

(Formation method of release film by shaped processing)

A release film which is formed into a surface uneven shape of the adherend, that is, a surface shape having the same shape as that of the surface to be adhered 2a, is disposed on at least one side, and an adhesive composition is applied to form a film by surface forming. The original piece of adhesive film.

Then, after appropriately dicing the strips in accordance with the width of the surface irregularities of the original sheet, the adhesive sheet for cutting the strips is peeled off on one side of the strip in the next step, and the exposed one side of the strip is cut according to the shape. After the useless adhesive of the outer periphery of the outer shape is erased, the new release film wider than the outer cut size is reattached.

Further, in the next step, the sheet is cut into an operable shape, and the double-sided adhesive sheet 1 is produced.

(using the shaping method of the mold)

The adhesive composition is coated or injected into a mold which mimics the surface uneven shape of the adherend, that is, the surface shape of the adhered surface 2a, and forms a surface-formed adhesive sheet.

When the mold is only one side, after applying or injecting the adhesive composition, the release film is attached to the opposite side, and is adhered to it from above by a rubber roller or the like.

After the adhesive composition is cured, the release film is pulled, whereby the double-sided adhesive sheet 1 is separated from the mold.

The overflow is removed when the film is applied or injected into the mold, and the guide portion 10 is provided as needed, and the exposed adhesive sheet is attached to the release film.

Further, in the next step, the sheet is cut into an operable shape, and the double-sided adhesive sheet 1 is produced.

When the mold has two sides, after the adhesive composition is cured, the single-sided mold is removed, and as a compensation, the release film is attached, and the rubber sheet or the like is adhered thereto from above.

Thereafter, the release film is pulled, whereby the adhesive sheet is separated from the mold.

The overflow is removed when the film is applied or injected into the mold, and the guide portion 10 is provided as needed, and the exposed adhesive sheet is attached to the release film.

Further, in the next step, the sheet is cut into an operable shape, and the double-sided adhesive sheet 1 is produced.

The material of the mold is not particularly limited, and a polysiloxane resin or a fluorine resin excellent in mold release property can also be used. Moreover, even if it is a mold which does not have a mold release material, such as stainless steel and aluminum, it can use it by apply|coating various mold-release agents.

(by the method of forming the roll)

After the adhesive composition is applied between the two flat release films, the shaping roller which mimics the surface unevenness of the adherend, that is, the surface shape of the adhered surface 2a, is placed on at least one side, and is sandwiched between the other. Surface forming by passing between the rollers on one side, and film-forming adhesive sheets The original film.

Then, after the strip is appropriately cut in accordance with the width of the surface uneven shape of the original sheet, the adhesive sheet for cutting the strip is peeled off on one side in the next step, and the exposed adhesive sheet is formed in a shape of the shaped shape. After cutting and erasing the useless adhesive edge outside the shape, reattach the new release film wider than the outer cut size.

Further, in the next step, the sheet is cut into an operable shape, and the double-sided adhesive sheet 1 is produced.

Regarding the roll temperature, the temperature at which the forming roll is placed between the rolls on the other side to form a surface is preferably room temperature or higher, more preferably 80 ° C or higher, and still more preferably 100 ° C or higher.

(by layering)

The original sheet of the flat adhesive sheet having the release film of the two-area layer is appropriately cut into long strips, and the first first adhesive sheet cut into the shape of the visible opening surface 2c and the surface 2d cut into the step portion 2b are prepared in advance. A flat second adhesive sheet having a shape different in shape.

Thereafter, the release film on the side of each of the faces is peeled off, and the exposed adhesive faces are reattached to each other to form a double-sided adhesive sheet 1 having a desired surface shape.

<Processing steps after shaping>

It is preferable that the double-sided adhesive sheet 1 is processed so that the gel fraction of the adhesive sheet 1 becomes 40% or more after forming the same surface shape as the uneven shape of the bonding surface of the adherend.

In this case, it is more preferable to carry out the treatment so that the gel fraction is 50% or more, and it is more preferable to carry out the treatment so as to be 60% or more.

After the shaping is performed as described above, the gel fraction of the adhesive sheet 1 is treated to be 40% or more, whereby the following effects can be obtained: the shape stability of the adhesive sheet 1 during storage is improved, and the surface is improved. Protective panel, touch panel and image display panel After that, the durability is improved.

For the adjustment of the gel fraction, various methods can be used.

For example, in the case of thermal crosslinking, the gel fraction can be increased by heating the adhesive sheet. At this time, the gel fraction can be adjusted by changing the temperature or time during heating or heating and drying.

Further, in the case where the ultraviolet rays are crosslinked, the gel fraction can be increased by irradiating the adhesive sheet with ultraviolet rays.

For example, the gel fraction can be adjusted by changing the amount of ultraviolet irradiation. At this time, the irradiation amount of the ultraviolet rays is preferably from 100 to 10,000 mJ/cm ² , more preferably from 250 to 1,500 mJ/cm ² , still more preferably from 500 to 1,000 mJ/cm ² .

<Better implementation>

As a preferred embodiment of the method for producing the double-sided adhesive sheet 1, the adhesive composition having a gel fraction of less than 40%, particularly less than 20%, is formed into a sheet form to form a sheet-like adhesive. The composition of the composition, and then at least one side of the sheet-like adhesive composition, is shaped to have the same surface shape as the concave-convex shape of the adhering surface of the adherend, and then the sheet-like adhesive composition is hardened by heat or light. The treatment is carried out such that the gel fraction of the sheet-like adhesive composition is 40% or more, particularly 60% or more.

Further, as another example of a preferred embodiment, a method of producing the double-sided adhesive sheet 1 is as follows: an adhesive composition having a gel fraction of less than 40%, particularly less than 20%, is formed into a sheet into a sheet. The adhesive composition, and then at least one side of the sheet-like adhesive composition, is shaped to have the same surface shape as the concave-convex shape of the adhering surface of the adherend, and then adhered to the adhesive body via the sheet-like adhesive composition Then, the sheet-like adhesive composition is cured by heat or light, and the gel fraction of the sheet-like adhesive composition is treated in an amount of 40% or more, particularly 60% or more.

[Examples]

Hereinafter, the examples and comparative examples will be described in further detail. But the invention is Not limited to these.

First, in order to produce the double-sided adhesive sheet of the present invention, an adhesive sheet (S-0) was produced by the following production example.

[Manufacturing example]

Preparation of 2-ethylhexyl acrylate (Homopolymer Tg (glass transition point of polymer obtained by polymerizing 2-ethylhexyl acrylate only): -70 ° C) 50 parts by weight, vinyl acetate (homopolymer) Tg + 32 ° C) 45 parts by weight, and acrylic acid (homopolymer Tg + 106 ° C) 5 parts by weight of the acrylate copolymer A (Mn = 65400, Mw = 167000, Mw / Mn = 2.56) . An ultraviolet curable resin pentaerythritol triacrylate (Nippon Nakamura Co., Ltd. "ATM-4PL" 70 g as a crosslinking agent and 4-methyl group as a photopolymerization initiator" was mixed with 1 kg of the acrylate copolymer A. The adhesive resin composition (A-1) was prepared by using 15 g of benzophenone.

The one side surface was treated as a peelable extended polyethylene terephthalate film (manufactured by Panac Co., Ltd., extended PET film "NP75Z01", thickness: 75 μm), the above-mentioned adhesive resin composition (A) -1) heating and melting, coating with an applicator so as to have a thickness of 150 μm, and then coating the single side as a peelable extended polyethylene terephthalate film by abutting (Toyo Textile Co., Ltd.) Manufactured by the company, extending the single side of the PET film "E7006", thickness 38 μm), and making an adhesive sheet comprising an extended PET film/ultraviolet crosslinkable intermediate resin layer (A-1, thickness 150 μm) / extended PET film ( S-0).

[Example 1] (Production of Adhesive Sheet 1)

The stretched PET film "E7006" was peeled off from the above-mentioned adhesive sheet (S-0) to form an adhesive sheet 1. The physical property evaluation results of the adhesive sheet 1 are shown in Table 1.

[Embodiment 2] (Production of Adhesive Sheet 2)

The pressure-sensitive adhesive sheet (S-0) produced as described above was irradiated with ultraviolet rays by a high-pressure mercury lamp so that the cumulative light amount at a wavelength of 365 nm became 250 mJ from the side of the polyethylene terephthalate film. Thereafter, the stretched PET film "E7006" was peeled off to obtain an adhesive sheet 2. The physical property evaluation results of the adhesive sheet 2 are shown in Table 1.

[Example 3] (Production of Adhesive Sheet 3)

The pressure-sensitive adhesive sheet (S-0) prepared above was irradiated with ultraviolet rays by a high-pressure mercury lamp from the side of the polyethylene terephthalate film so that the cumulative light amount at a wavelength of 365 nm became 500 mJ. Thereafter, the stretched PET film "E7006" was peeled off to obtain an adhesive sheet 3. The physical property evaluation results of the adhesive sheet 3 are shown in Table 1.

[Example 4] (Production of Adhesive Sheet 4)

The pressure-sensitive adhesive sheet (S-0) produced as described above was irradiated with ultraviolet rays by a high-pressure mercury lamp so that the integrated light amount at a wavelength of 365 nm became 1000 mJ from the side of the polyethylene terephthalate film. Thereafter, the stretched PET film "E7006" was peeled off to obtain an adhesive sheet 4. The physical property evaluation results of the adhesive sheet 4 are shown in Table 1.

[Comparative Example 1] (Production of Adhesive Sheet 5)

The pressure-sensitive adhesive sheet (S-0) produced as described above was irradiated with ultraviolet rays by a high-pressure mercury lamp so that the integrated light amount at a wavelength of 365 nm became 2000 mJ from the side of the polyethylene terephthalate film. Thereafter, the stretched PET film "E7006" was peeled off to obtain an adhesive sheet 5. The physical property evaluation results of the adhesive sheet 5 are shown in Table 1.

[Example 5] (Production of Adhesive Sheet 6)

The pressure-sensitive adhesive sheet (S-0) prepared above was irradiated with ultraviolet rays by a high-pressure mercury lamp from the side of the polyethylene terephthalate film so that the cumulative light amount at a wavelength of 365 nm became 500 mJ. Thereafter, the stretched PET film "E7006" was peeled off, and as a compensation, a polyfluorene-coated non-stretched polypropylene film (chlorinated polypropylene film) was produced (Suntox Co., Ltd.) Suntox RS02"), and the adhesive sheet 6 is obtained. The physical property evaluation results of the adhesive sheet 6 are shown in Table 2.

[Embodiment 6] (Production of Adhesive Sheet 7)

The adhesive sheet (S-0) produced as described above was irradiated with ultraviolet light by a high-pressure mercury lamp so that the integrated light amount at a wavelength of 365 nm became 500 mJ from the side of the polyethylene terephthalate film, and the stretched PET film "E7006" was not peeled off. The adhesive sheet 7 was obtained. The physical property evaluation results of the adhesive sheet 7 are shown in Table 2.

The adhesive sheets 1 to 7 obtained as described above were evaluated as follows.

(1) Gel fraction

After removing all of the stretched PET film or the non-extended CPP film from the obtained adhesive sheets 1 to 7, the cut was performed, and about 0.05 g of the adhesive sheets were respectively taken.

The adhesive sheet taken is packaged in a SUS (Steel Use Stainless) mesh (#200) of a mass (X) prepared in advance in a bag shape, and the sample is closed to prepare a sample, and the quality of the sample is measured ( Y). The sample was stored in a dark place at 23 ° C for 24 hours while being immersed in 100 ml of ethyl acetate, and the sample was taken out and heated at 70 ° C for 4.5 hours to evaporate ethyl acetate, and the dried sample was measured. Quality (Z). For each of the measured masses, the gel fraction was calculated by the following formula.

Gel fraction (%) = [(Z-X) / (Y-X)]

(2) Adhesive sheet shaping treatment test

As shown in Fig. 13, the following evaluation forming mold was used as a substitute for the actual press mold for the adhesive sheet forming treatment. A recess of 40 mm × 70 mm and a depth of 80 μm was formed in the center portion of the polyoxynoxy resin of 80 mm × 110 mm × 1 cm in thickness, and a frame having a width of 20 mm was held in the peripheral portion to prepare a shape-molding mold for evaluation.

The obtained adhesive sheets 1 to 7 were cut into 80 × 110 mm, and the stretched PET film "NP75Z01" having a thickness of 75 μm was placed below, placed on a heating plate heated to 100 ° C, and preheated for 5 minutes. The evaluation shaping mold was placed on the preheated adhesive sheet, and a 2 kg cast iron weight was placed thereon, and after standing for 10 seconds, the adhesive sheet was taken together with the evaluation shaping mold from the heating plate. Start. After cooling at 23 ° C for 5 minutes, the adhesive sheet was separated from an extended PET film "NP75Z01" by a shaping treatment mold, and an adhesive sheet having a convex portion of a rectangular shape of 40 mm × 70 mm × height 80 μm was obtained.

As the adhesive sheet forming treatment test, the shape of the above-mentioned convex portion was evaluated by the following criteria. Further, the adhesive sheet 6 was peeled off from the non-extended CPP film "Suntox RS02", and the adhesive sheet 7 was peeled off after the stretched PET film "E7006" was evaluated.

○: The base or corner of the convex portion is not round and has a sharp shape. The ridge line of the rectangular parallelepiped forming the convex portion is linear.

△: The base or corner of the convex portion is slightly rounded. Although the ridge line of the rectangular parallelepiped forming the convex portion has a plurality of corrugations, it is substantially linear, and there is no problem in practical use.

×: The base or corner of the convex portion is relatively round. The ridgeline forming the cuboid of the convex portion is curved or curved, and is not linear.

(3) Printing step followability test

As shown in Fig. 14, the following glass substrate for evaluation was used as a substitute for the image display device constituent member having the step portion on the adhering surface. A white printing having a width of 10 mm and a thickness of 80 μm (total light transmittance: 0%) was applied to the peripheral portion of the glass plate (60 mm × 90 mm × thickness: 0.5 mm), and the peripheral portion having a printing step of 80 μm, that is, the central portion having a height was produced. A glass substrate for evaluation of a concave portion of 80 μm.

In addition, a polarizing plate ("NWF-KDSEGHC-ST22" manufactured by Nitto Denko Corporation) was used as a test adherend to be bonded to the glass substrate for evaluation. The above polarizing plate was bonded to one side of a glass plate (60 mm × 90 mm × thickness 0.5 mm) using the entire surface.

As the adhesive sheet having the same shape as the uneven shape of the bonding surface of the adherend, the adhesive sheets 1 to 7 having the convex portions of the rectangular parallelepiped type produced by the above (2) adhesive sheet forming treatment test were used. The convex portion of the adhesive sheet was attached to the concave portion of the evaluation glass substrate by a hand press roller by embedding. Then, the stretched PET film "NP75Z01" was peeled off, and the polarizing plate and the glass plate were bonded to the entire surface after being exposed, and the pressure-sensitive adhesive sheet and the glass plate were pressed and pressed under reduced pressure (absolute pressure: 5 kPa), and then autoclaved ( At 60 ° C, 0.2 MPa, and 20 minutes), the final adhesion was performed, and a laminate for the evaluation of the print step followability was produced.

The laminate for the above-mentioned printing step followability evaluation was allowed to stand under normal conditions (temperature: 23° C., humidity: 50%) for one day, and then the appearance was visually observed and evaluated as follows.

○: No bulging or peeling of the adhesive sheet occurred near the printing step.

×: Adhesion or peeling of the adhesive sheet occurred in the vicinity of the printing step.

As shown in Examples 1 to 4, by using the adhesive composition in which the gel fraction of the double-sided adhesive sheet before bonding is less than 40%, only the mold at a normal temperature is used to press the mold. The preheated sheet can be shaped. Further, the convex portion subjected to the shaping treatment may have the same surface shape as the concave-convex shape of the shaping treatment mold. The prompt can be shaped into the same shape as the concave-convex shape of the adhering surface of the adherend. Therefore, it is possible to produce an adhesive sheet having a high degree of followability of the printing step.

In the adhesive sheets having a lower gel fraction, as shown in Examples 1 to 3, since the bonding of the molecular chains constituting the adhesive is suppressed to an appropriate range, when the forming treatment is performed by a pressing treatment or the like, The shape is kept intact.

On the other hand, in Comparative Example 1, since the gel fraction of the double-sided adhesive sheet before bonding was 40% or more, the ridge line of the rectangular parallelepiped of the convex portion which was subjected to the shaping treatment was not linear or the like, and it was impossible to form and shape the treatment. The same shape of the mold results in an adhesive sheet with poor step followability.

As shown in Comparative Example 1, the adhesive sheet having a high gel fraction has a strong and dense bond between the molecular chains constituting the adhesive, so that the adhesive cannot be formed even if the forming treatment is performed by pressing treatment or the like. The shape of the mold is processed so that it does not flow. Therefore, it is impossible to form the convex portion having the same surface shape as that of the shaping|molding process mold, and it becomes the adhesive sheet which is inferior to the step followability.

Further, in the fifth and sixth embodiments in which the release film is provided on the side to be pressed, the convex portion having the shaping treatment has the same surface shape as the shaping treatment mold, and the adhesive sheet having high printing step followability can be produced. .

Here, as in the case of the fifth embodiment, the release film is a non-stretched film, and the convex portion having the same surface shape as the shaping-molding mold can be more accurately formed.

Claims (14)

A method for manufacturing a double-sided adhesive sheet for an image display device, characterized in that it is used for bonding two types of adherends selected from a surface protection panel, a touch panel and an image display panel The adhesive sheet manufacturing method, and the double-sided adhesive sheet before bonding is an adhesive composition having a gel fraction of less than 40%, and the bonding surface with the adherend before bonding the above-mentioned adherend The surface shape having the same concavo-convex shape is formed on at least one side of the double-sided adhesive sheet. A method of producing a double-sided adhesive sheet for an image display device according to claim 1, wherein the adhesive composition is a photocurable adhesive composition. The method for producing a double-sided adhesive sheet for an image display device according to claim 1 or 2, wherein the method of forming the same shape as the uneven shape of the bonding surface of the adherend is to imitate the adherend The shape of the mold is directly pressed against at least one side of the double-sided adhesive sheet for shaping. The method for producing a double-sided adhesive sheet for an image display device according to claim 1 or 2, wherein the method of forming the same shape as the uneven shape of the bonding surface of the adherend is to imitate the adherend The mold of the shape is shaped by pressing against the at least one side surface of the double-sided adhesive sheet via the release film. A method of producing a double-sided adhesive sheet for an image display apparatus according to claim 4, wherein the release film is a non-stretched film. A method of producing a double-sided adhesive sheet for an image display apparatus according to claim 4, wherein the release film is any one of an unstretched polypropylene film, an unstretched polyethylene film, and an unstretched polyester film. The method for producing a double-sided adhesive sheet for an image display device according to claim 5, wherein the release film is any one of a non-stretched polypropylene film, an unstretched polyethylene film, and an unstretched polyester film. The method for producing a double-sided adhesive sheet for an image display device according to claim 1 or 2, which is characterized in that the shape is the same as the concave-convex shape of the bonding surface of the adherend, and is treated to make the double-sided adhesive The gel fraction of the sheet is 40% or more. The method for producing a double-sided adhesive sheet for an image display device according to claim 1 or 2, which is formed by irradiating ultraviolet rays after forming a surface shape having the same concave-convex shape as that of the bonding surface of the adherend. The gel fraction of the double-sided adhesive sheet is 40% or more. A double-sided adhesive sheet for an image display device with a release film, which is characterized in that it is suitable for bonding any two kinds of adherends selected from a surface protection panel, a touch panel and an image display panel. a double-sided adhesive sheet with a release film, the double-sided adhesive sheet has a gel fraction of less than 40%, and has at least one side surface having the same concave and convex shape as the bonding surface of the adherend, and double-sided The adhesive sheet has a release film on one or both sides. A double-sided adhesive sheet for an image display apparatus with a release film according to claim 10, wherein the double-sided adhesive sheet is photocurable. The image display device with a release film according to claim 10 or 11 is a double-sided adhesive sheet in which a peripheral portion of the release film protrudes outward from a peripheral portion of the double-sided adhesive sheet. The double-sided adhesive sheet for an image display device with a release film according to claim 10 or 11, wherein at least the release film on one side has a shape shaped to have the same surface shape as that of the bonding surface. The double-sided adhesive sheet for the image display device with the release film of claim 10 or 11, wherein the peripheral portion of the release film protrudes outward from the peripheral portion of the double-sided adhesive sheet and is on the periphery of the release film. One or a portion of the portion has a guide between the two release films.