JP2010254869A - Photocurable self-adhesive sheet and method for forming photocurable self-adhesive layer by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a photocurable self-adhesive sheet capable of transferring a high-precision photocurable self-adhesive layer on only the surface on which a self-adhesive layer is to be formed and to provide a method for forming a photocurable self-adhesive layer by using the same. <P>SOLUTION: What is provided is the photocurable self-adhesive sheet which is a photocurable self-adhesive sheet having a photocurable self-adhesive layer 11 comprising a self-adhesive photocurable composition having tackiness, wherein release sheets 12 and/or 13 are formed on one or both of the surfaces of the photocurable self-adhesive layer, the thixotropic index (η) of the photocurable composition is represented by the formula: η=G'<SB>0.01 Hz</SB>/G'<SB>46.4 Hz</SB>[wherein (G'<SB>0.01 Hz</SB>) is a storage modulus at the ordinary temperature and at a frequency of 0.01 Hz, and (G'<SB>46.4 Hz</SB>) is a storage modulus at the ordinary temperature and at a frequency of 46.4 Hz] and η>1, and a method for forming a self-adhesive layer by using the same. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a photocurable pressure-sensitive adhesive sheet for transferring a photocurable pressure-sensitive adhesive layer only to a contacted portion, and a method for forming a photocurable pressure-sensitive adhesive layer using the same, and more particularly to an image display panel substrate used for an electronic paper display. The present invention relates to a method for forming a photocurable pressure-sensitive adhesive layer only on the end face of a convex portion on the surface having irregularities such as.

  In general, as a method for forming an adhesive layer on the surface of a planar substrate, there are a method of applying a liquid adhesive and a method of laminating an adhesive film produced in a film shape (Patent Document 1). In addition, in order to form an adhesive layer only on the convex end surface of the surface having irregularities of the substrate as shown in FIG. 1, a method of masking the concave portion and applying a liquid adhesive only to the convex end surface, There is a method in which an adhesive film is punched out in accordance with the shape of the end face of the convex part and attached to the end face of the convex part. Examples of such a member that requires a technique for forming an adhesive layer only on the convex end surface of the surface having irregularities include an image display panel substrate used for an electronic paper display.

  In recent years, electronic paper displays have been studied as electrophoretic, thermal rewritable, and dry types as information display devices that can replace liquid crystals. Among them, the dry-type image display panel has, for example, a plurality of display cells provided by partition walls between two substrates facing each other (one substrate is transparent), and is insulated in the cells. The structure which enclosed the property coloring particle | grains etc. is included (patent document 2). In this case, a substrate having a surface having unevenness as shown in FIG. 1 and a planar substrate are bonded together via an adhesive layer, and a space formed in the recess is used as a display cell. Since the display cell of the image display panel needs to be formed with high accuracy, the adhesive layer formed only on the convex end surface of the surface having the irregularities of the substrate has a constant layer thickness and an adhesive in the concave portion. It is necessary to be a highly accurate adhesive layer that does not intrude.

JP 2008-62571 A JP 2004-317526 A

  However, in the method for forming an adhesive layer using a liquid adhesive or an adhesive film as described above, complicated steps such as masking, punching of the adhesive film, and alignment (positioning) are required. Furthermore, in the case of a method of applying a liquid adhesive, it is difficult to accurately mask the recess, and the adhesive may enter the recess due to misalignment, or the layer thickness may become uneven. There is. Moreover, also when using an adhesive film, it is difficult to affix the adhesive film punched in the shape of the convex part end surface to a convex part end surface without position shift, and an adhesive film may protrude in a recessed part. Accordingly, it is difficult to form the adhesive layer with high accuracy only on the end face of the convex portion depending on the shape of the unevenness.

  In particular, in the case of a photo-curing pressure sensitive adhesive, it does not harden even when irradiated with UV in the presence of oxygen. Therefore, in order to cure the pressure sensitive adhesive that has entered the recess, it is necessary to remove oxygen from the atmosphere gas by nitrogen substitution or the like. . Moreover, even if it removes oxygen by nitrogen substitution etc. and performs UV irradiation, it is difficult to make it harden | cure completely and an unhardened material will remain. In this state, when enclosing particles or the like using the space formed in the recess as in the image display panel base plate, the particles and the like may be contaminated by the uncured adhesive component. .

  Therefore, the object of the present invention is to form a photocurable pressure-sensitive adhesive layer on the end face of the convex portion of the surface having unevenness, particularly in the case of forming a photocurable pressure-sensitive adhesive layer using the above-mentioned liquid pressure-sensitive adhesive or pressure-sensitive adhesive film. A photocurable pressure-sensitive adhesive sheet capable of transferring a highly accurate photocurable pressure-sensitive adhesive layer only to the end face of the convex portion without causing problems, and a method for forming a photocurable pressure-sensitive adhesive layer using the same There is.

  The above object is a photocurable pressure-sensitive adhesive sheet having a photocurable pressure-sensitive adhesive layer made of an adhesive photocurable composition, and a release sheet is provided on one or both surfaces of the photocurable pressure-sensitive adhesive layer. The thixotropic index (η) of the photocurable composition is represented by the following formula:

[However, (G ^′ _{0.01 Hz} ) indicates storage elastic modulus at room temperature and frequency 0.01 Hz, and (G ^′ _{46.4 Hz} ) indicates storage elastic modulus at normal temperature and frequency 46.4 Hz. ]
And is achieved by a photocurable pressure-sensitive adhesive sheet characterized by η> 1.

  In general, thixotropy refers to the property that fluidity increases when a shearing force such as stirring is applied, and returns to its original state when allowed to stand, and may be evaluated based on the shear rate dependence of viscoelasticity (for example, the rotational speed of stirring). If the viscosity is higher than the condition where the rotational speed is higher, the thixotropy is lower). In the present invention, when the frequency dependence of the storage modulus is expressed as a thixotropic index (η) as in the above formula, the thixotropic index (η) of the adhesive photocurable composition is expressed as η> By setting it to 1, it can be set as the adhesion layer without spinnability. FIG. 2 is a diagram for explaining the relationship between the frequency [Hz] and the storage elastic modulus [Pa]. In the photocurable composition concerning this invention, a relationship like a continuous line ((eta)> 1) is shown. Thereby, when the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet of the present invention is brought into contact with the surface forming the pressure-sensitive adhesive layer and the release sheet is peeled off, the pressure-sensitive adhesive layer is transferred from the release sheet only to the portion where the pressure-sensitive adhesive layer is contacted, and is brought into contact. The non-adhesive part of the adhesive layer remains on the release sheet without being pulled by the contact part of the adhesive layer. Therefore, the photocurable pressure-sensitive adhesive sheet of the present invention is a pressure-sensitive adhesive sheet capable of transferring the pressure-sensitive adhesive layer only to the surface on which the pressure-sensitive adhesive layer is formed, in particular, the convex end surface of the surface having irregularities. The storage elastic modulus is measured by changing the frequency with a dynamic viscoelasticity measuring device (Rheostress RS300 (manufactured by HAAKE)).

Preferred embodiments of the photocurable pressure-sensitive adhesive sheet of the present invention are as follows.
(1) The photocurable composition contains a tackifier having a solubility parameter of 8.5 to 9.5 (J / cm ³ ) ^1/2 . The solubility parameter (hereinafter abbreviated as SP value) is a cohesive energy density (CED), that is, a value obtained by multiplying the evaporation energy per unit volume of one molecule by a factor of 1/2, and the magnitude of the polarity per unit volume of the substance. (Refer to “Practical Plastic Glossary of Terms, Second Edition”, page 565 (Showa 45, Plastic Age Co., Ltd.)). The SP value of the polymer used in the photocurable composition according to the present invention is, for example, about 10 to 12. If the tackifier has the above SP value, the photocuring property is due to the property of appropriate phase separation from the polymer. It is considered that the thixotropic index (η) of the composition can be made larger than 1.
(2) The tackifier is at least one compound selected from the group consisting of terpene resins, modified terpene resins, terpene phenol resins, and hydrogenated terpene resins.
(3) Content of the said tackifier is 0.9-3.5 mass% with respect to a photocurable composition.
(4) The photocurable composition contains fine particles having an average particle diameter of 1 to 300 nm. Such fine particles are generally used as a thixotropic agent, and the thixotropic index (η) of the photocurable composition according to the present invention can be made larger than 1.
(5) The fine particles are transparent fine particles.
(6) The transparent fine particles are silica fine particles.
(7) Content of the said fine particle is 0.4-2.2 mass% with respect to a photocurable composition.
(8) The said peeling sheet contains a polymer film and the peeling layer provided in the surface so that a photocurable adhesion layer may be contacted.

In addition, the above purpose is as follows:
(1) When the photocurable pressure-sensitive adhesive sheet of the present invention has release sheets on both sides, a step of removing one of the release sheets;
(2) A step of bringing the photocurable pressure-sensitive adhesive layer of the photocurable pressure-sensitive adhesive sheet into contact with and pressing the convex end surface of the surface having irregularities;
(3) A step of forming an adhesive layer only on the end face of the convex portion by removing the release sheet of the photocurable adhesive sheet from the surface having the irregularities;
It is achieved by a method for forming a photocurable adhesive layer containing In the method of the present invention, since the photocurable pressure-sensitive adhesive sheet of the present invention is used, the pressure-sensitive adhesive layer is transferred from the release sheet only to the convex portion end surface in contact with the pressure-sensitive adhesive layer, and the other portions of the pressure-sensitive adhesive layer are It remains on the release sheet without being pulled by the part of the adhesive layer in contact with the end face of the convex portion, and can be removed together with the release sheet. Thereby, an adhesive layer can be formed with high precision only on the convex end face of the surface having irregularities.

  As a preferable aspect of the method for forming the photocurable pressure-sensitive adhesive layer of the present invention, the uneven surface is the surface of the image display panel substrate. The method of the present invention is effective when a photocurable pressure-sensitive adhesive layer is formed only on the convex end face of the surface of a substrate having a fine concavo-convex pattern of an image display panel substrate used for an electronic paper display or the like.

    According to the present invention, when the photocurable adhesive layer is formed only on the convex end surface of the uneven surface, the photocurable adhesive layer is formed with a uniform layer thickness and high accuracy without allowing the adhesive to enter the concave portion. Can be formed. Therefore, when the formed photocurable pressure-sensitive adhesive layer is made effective by UV irradiation, since there is no penetration of the pressure-sensitive adhesive into the recess, it is not necessary to remove oxygen from the atmospheric gas by nitrogen substitution or the like. In addition, since an uncured product does not remain in the recess, when the particle is encapsulated in a space formed in the recess as in the image display panel base plate, the particle or the like is caused by an uncured adhesive component. Is no longer contaminated.

  Furthermore, as in the case of forming a similar pressure-sensitive adhesive layer using a liquid pressure-sensitive adhesive or pressure-sensitive adhesive film, it is not necessary to mask the concave portion or punch the pressure-sensitive adhesive film into the shape of the convex end face, Can be simplified. This also eliminates the need for equipment such as a punching device, thereby reducing costs.

It is a schematic perspective view which shows an example of a board | substrate provided with the surface which has an unevenness | corrugation. It is a figure for demonstrating the frequency dependence (thixotropic index ((eta))) of a storage elastic modulus as evaluation of thixotropy in this invention. It is a schematic sectional drawing which shows a typical example of the photocurable adhesive sheet of this invention. It is a schematic sectional drawing which shows a typical example of the formation method of the photocurable adhesive layer of this invention. It is a schematic sectional drawing which shows a typical example of the continuous formation method of a photocurable adhesion layer according to this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 3 is a schematic sectional view showing a typical example of the embodiment of the photocurable pressure-sensitive adhesive sheet 10 of the present invention. The photocurable adhesive layer 11 is provided with a release sheet 12 made of a polymer film 12b having a release layer 12a on one surface and a release sheet 13 made of a polymer film 13b having a release layer 13a on the other surface. Yes. The release sheets 12 and 13 protect the photocurable pressure-sensitive adhesive layer 11 and ensure the film self-supporting property of the photocurable pressure-sensitive adhesive sheet 10. The release sheets 12 and 13 may be on at least one side, but it is preferable to provide them on both sides in consideration of contamination and damage of the photocurable adhesive layer 11. In particular, when using a long sheet, it is preferable also in terms of handling properties.

  When the photocurable pressure-sensitive adhesive layer 11 according to the present invention comes into contact with the surface (particularly, the convex end surface of the surface having irregularities) that forms the photocurable pressure-sensitive adhesive layer in a state in which the release sheet 12 is provided, The spinnability is controlled so that only the contacted portion is transferred from the release sheet 12 and the non-contacted portion remains on the release sheet 12. For this purpose, the photocurable adhesive layer 11 has the following formula:

[However, (G ^′ _{0.01 Hz} ) indicates storage elastic modulus at room temperature and frequency 0.01 Hz, and (G ^′ _{46.4 Hz} ) indicates storage elastic modulus at normal temperature and frequency 46.4 Hz. ] Is a photocurable composition blended so that the thixotropic index (η) (frequency dependence of storage elastic modulus) represented by η> 1.

  The photocurable composition according to the present invention (generally including a polymer and a reactive diluent having a photopolymerizable functional group) can contain any additive as long as the thixotropic index (η) can be satisfied. It may be contained.

For example, a tackifier having an SP value of 8.5 to 9.5 (J / cm ³ ) ^1/2 can be added. The SP value is calculated according to the following formula (numerical formula I) (see “Practical Plastic Glossary, Second Edition”, page 565 (Showa 45, Plastic Age Co., Ltd.)).

  The reason why the thixotropic index (η) can be controlled using such a tackifier is not clear, but the SP value of the polymer used in the photocurable composition according to the present invention is, for example, about 10 to 10 for a methacrylate resin. When the tackifier having the above SP value is appropriately added, the thixotropy index (η) of the photocurable composition can be made larger than 1 due to the property of appropriate phase separation from the polymer. Conceivable.

The tackifier used in the present invention has a function of increasing the tackiness when added to a polymer substance, and any tackifier can be used as long as the thixotropic index (η) of the photocurable composition can be controlled. . Specifically, terpene resin, modified terpene resin such as aromatic modified terpene resin, terpene phenol resin, hydrogenated terpene resin, coumarone indene resin, coumarone resin, naphthenic oil, phenol resin, rosin, rosin ester, hydrogenated rosin derivatives, alpha-pinene resins, alkylphenol-acetylene resin, alkylphenol-formaldehyde resins, styrene resins, C ₅ petroleum resins, C ₉ petroleum resins, alicyclic petroleum resins, C ₅ / C ₉ copolymerization system Examples include petroleum resins and xylene-formaldehyde resins, among which those having an SP value in the above range are used. In particular, terpene resins, modified terpene resins, terpene phenol resins and hydrogenated terpene resins are preferred. These tackifiers may be used alone or in combination of two or more. The addition amount of the tackifier is not particularly limited, but is preferably 0.9 to 3.5% by mass, and more preferably 1.8 to 2.6% by mass with respect to the photocurable composition.

  Another additive for controlling the thixotropic index (η) includes fine particles having an average particle diameter of 1 to 300 nm. Such fine particles are generally used as a thixotropic agent, and the thixotropic index (η) of the photocurable composition according to the present invention can be made larger than 1.

  The fine particles used in the present invention may be either inorganic fine particles or organic fine particles as long as the thixotropic index (η) of the photocurable composition can be controlled. Examples of the fine particles include inorganic particles such as silica, alumina, aluminosilicate, kaolinite, calcium carbonate, barium sulfate, and glass. Organic fine particles include acrylic resin, polycarbonate resin, and urethane resin. , Urea-based resin, benzoguanamine resin, benzoguanamine-melamine-formaldehyde condensate particles, etc., which may be either hydrophobic or hydrophilic in their surface properties, and these may be used alone or in combination. Can be used. Transparent fine particles are preferable, and silica is particularly preferable in that the use of the photocurable pressure-sensitive adhesive sheet (a member having a surface to which the pressure-sensitive adhesive layer is transferred) is less likely to occur. As the silica fine particles, for example, amorphous fumed silica, hydrophobic fumed silica, hydrophilic fumed silica, hydrophobic wet silica, hydrophilic wet silica, etc. can be used. The addition amount of the fine particles is not particularly limited, but is preferably 0.4 to 2.2% by mass, and more preferably 0.9 to 1.8% by mass with respect to the photocurable composition. In the present invention, the above-mentioned tackifier and fine particles may be used in combination to control the thixotropic index (η) of the photocurable composition.

  The photocurable composition according to the present invention comprises a polymer, a reactive diluent (monomer and oligomer) having a photopolymerizable functional group (generally a carbon-carbon double bond group, preferably a (meth) acryloyl group), and photopolymerization. It is composed of an initiator, an additive for controlling the thixotropy index (η), and other additives as desired.

  The polymer of the photocurable composition preferably includes a polymer having a glass transition temperature (Tg) of 60 ° C. or higher. Thereby, hardening of a photocurable adhesive layer can be performed at high speed. Further, since the cured shape also has a high Tg, it is possible to ensure strong adhesiveness. As a polymer having a glass transition temperature of 60 ° C. or more, if it has a polymerizable functional group, it can react with a reactive diluent, which is further advantageous for increasing the speed of curing. Moreover, by having a diisocyanate in the photocurable pressure-sensitive adhesive layer 11 by having a hydroxyl group, it becomes possible to slightly crosslink the polymer, and a layer in which the pressure-sensitive adhesive layer oozes out and the layer thickness fluctuation is largely suppressed can be obtained. Is particularly advantageous. Diisocyanates are effective to some extent even in polymers without hydroxyl groups.

  In the present invention, the release sheets 12 and 13 protect the photocurable pressure-sensitive adhesive layer 11, can be easily peeled off from the photocurable pressure-sensitive adhesive layer 11 during use, and the pressure-sensitive adhesive layer 11 is brought into contact with the surface forming the pressure-sensitive adhesive layer. Any part may be used as long as the part that is not in contact has a sticking property such that it remains on the release sheet. Preferably, it is a release sheet in which a release layer is provided on a polymer film as shown in FIG.

  The polymer films 12b and 13b may be of any type, for example, polyester resins such as polyethylene terephthalate, polycyclohexylene terephthalate, polyethylene naphthalate, nylon 46, modified nylon 6T, nylon MXD6, polyamide resin such as polyphthalamide, In addition to ketone resins such as polyphenylene sulfide and polythioether sulfone, and sulfone resins such as polysulfone and polyether sulfone, polyether nitrile, polyarylate, polyetherimide, polyamideimide, polycarbonate, polymethyl methacrylate, triacetyl A transparent resin film mainly containing an organic resin such as cellulose, polystyrene, or polyvinyl chloride can be used. Among these, polycarbonate, polymethyl methacrylate, polyvinyl chloride, polystyrene, and polyethylene terephthalate films can be suitably used, and polyethylene terephthalate films are particularly preferable. The thickness is preferably 10 to 200 μm, particularly preferably 30 to 100 μm.

  The release layers 12a and 13a may be of any type, but since the adhesive layer 11 is required to have adhesiveness, the adhesive layer 11 is a layer that does not deteriorate its adhesiveness due to transfer of the peelable component to the adhesive layer 11 or the like. Is preferred. Generally, it is a release layer with few peelable low molecular weight components. These are general release layers, and may be layers made of any of the following resins. That is, it may be formed from a thermoplastic resin or thermosetting resin that does not contain silicon atoms, or may be formed from a thermoplastic resin or a thermosetting silicone resin. A reactive silicone resin is preferred. In particular, it is preferable to use a polysiloxane (preferably dimethylpolysiloxane) having an unsaturated double bond group (preferably a vinyl group) and a hydrogenated polysiloxane (preferably dimethylpolysiloxane). Instead of the polysiloxane having an unsaturated double bond group, a polyalkylene oxide having an unsaturated double bond group can also be used.

  The release layers 12a and 13a can be obtained by dissolving or dispersing the above-mentioned silicone resin or the like in a solvent, applying it to a polymer film by reverse roll coating, gravure coating, bar coating, doctor blade coating, etc., and heating for an appropriate time. . The heating temperature varies depending on the type of resin used. In general, it is 100 to 150 ° C., preferably 120 to 140 ° C., and the heating time is generally 10 to 60 seconds, preferably 20 to 30 seconds. In general, the thickness of the release layers 12a and 13a is preferably 300 to 1500 nm and 500 to 800 nm. When the layer thickness is less than the above range, the coatability is not stable and it may be difficult to obtain a uniform coating film. On the other hand, if the coating is thickened beyond the above range, the adhesion and curability of the release layer itself may decrease. In the present invention, the release sheets 12 and 13 may be the same or different.

  Next, the formation method of the photocurable adhesive layer of this invention using the said photocurable adhesive sheet 10 is demonstrated in detail, referring drawings.

  FIG. 4 is a schematic cross-sectional view showing a typical example of the embodiment in the method for forming a photocurable adhesive layer of the present invention. First, the release sheet 13 is removed from the photocurable pressure-sensitive adhesive sheet 10 to expose one surface of the photocurable pressure-sensitive adhesive layer 11. The release sheet 12 is adhered to the other surface of the photocurable pressure-sensitive adhesive layer 11, and the pressure-sensitive adhesive layer 11 maintains the film self-supporting property (FIG. 4 (a): step (1)). Next, it arrange | positions so that the surface which has the unevenness | corrugation of the board | substrate 14 including the convex part end surface which forms an adhesion layer may be opposed to the surface of the photocurable adhesion layer 11 (FIG.4 (b)). Subsequently, the photocurable adhesive layer 11 is brought into contact with the convex end surface 15 and pressed. At this time, the strength of pressing is adjusted so that the photocurable adhesive layer 11 is in close contact with the convex end surface 15 and does not come into contact with the concave surface 16 (FIG. 4C: Step (2) above). This step is usually possible at room temperature, but temperature adjustment such as heating may be performed as necessary. Thereafter, when the release sheet 12 is removed from the uneven surface of the substrate 14, the photocurable adhesive layer 11c is formed only on the convex end face 15 (FIG. 4D: step (3)). In the method of the present invention, since the photocurable pressure-sensitive adhesive sheet 10 of the present invention is used, the portion of the photocurable pressure-sensitive adhesive layer 11 that is not in contact with the convex portion end surface 15 is in contact with the convex portion end surface 15. Without being pulled, the adhesive sheet remains attached to the release sheet 12 and is removed together with the release sheet 12. Therefore, the photocurable pressure-sensitive adhesive layer 11 c can be formed only on the convex portion end surface 15 with a uniform layer thickness without allowing the photocurable pressure-sensitive adhesive layer to enter the concave surface 16.

  Moreover, you may perform the method of this invention continuously using a elongate photocurable adhesive sheet. FIG. 5 is a schematic cross-sectional view showing a typical example of a method for continuously forming a photocurable adhesive layer according to the present invention.

  First, the photocurable pressure-sensitive adhesive sheet 20 is sent out from the feed roll 28a, and the release sheet 23 is taken up and removed by the take-up roll 28b via the guide roll 28c. The photocurable adhesive layer 21 fixed to the release sheet 22 is exposed and conveyed in the direction of the arrow. On the other hand, the board | substrate 24 which has an uneven | corrugated pattern is conveyed by the conveyance conveyor 27 in the arrow direction in conjunction with the moving speed of the photocurable adhesive sheet 20. And when the board | substrate 24 comes to the position of the press roll 29, the press roll 29 makes the adhesive layer 21 the convex part end surface 25 of the surface which has the unevenness | corrugation of the board | substrate 24 from the peeling sheet 22 side of the photocurable adhesive sheet 20. FIG. Press. As a result, the portion of the adhesive layer 21 that is in contact with the convex end face 25 is transferred to the convex end face 25. Further, the photocurable pressure-sensitive adhesive sheet 20 and the substrate 24 are transported in conjunction with each other, and the portion not contacting the convex end surface 25 of the pressure-sensitive adhesive layer 21 together with the release sheet 22 is removed from the surface of the substrate 24 having the irregularities. . Pressing and peeling are continuously performed, and the photocurable adhesive layer 21 c is formed on the convex portion end surface 25 of the substrate 24. The release sheet 22 and the adhesive layer 21 remaining on the release sheet 22 are wound and collected by the take-up roll 28d.

  In the method of the present invention, the convex end face of the surface having irregularities may be any part, and may be a plate-like thing such as the above-mentioned substrate or a surface such as an end part of an assembly in which pipes are bundled. As for the surface which has such an unevenness | corrugation, the surface of the board | substrate of the image display panel used for an electronic paper display is mentioned preferably, for example.

  Examples of the polymer (preferably having a glass transition temperature of 60 ° C. or higher) contained in the photocurable composition forming the photocurable adhesive layer of the photocurable adhesive sheet of the present invention include acrylic resin, polyvinyl acetate, vinyl acetate / (Meth) acrylate copolymer, ethylene / vinyl acetate copolymer, polystyrene and its copolymer, polyvinyl chloride and its copolymer, butadiene / acrylonitrile copolymer, acrylonitrile / butadiene / styrene copolymer, methacrylate / Acrylonitrile / butadiene / styrene copolymer, 2-chlorobutadiene-1,3-polymer, chlorinated rubber, styrene / butadiene / styrene copolymer, styrene / isoprene / styrene block copolymer, epoxy resin, polyamide, polyester, Polyurethane, cellulose ester It can be mentioned cellulose ethers, polycarbonates, polyvinyl acetal.

  In the present invention, an acrylic resin is preferable from the viewpoint of excellent adhesion and curability. As described above, the acrylic resin is particularly preferably an acrylic resin having a polymerizable functional group or an acrylic resin having a hydroxyl group. In addition, when the acrylic resin contains at least 50% by mass (especially 60 to 90% by mass) of repeating units of methyl methacrylate, it is easy to obtain an acrylic resin having a Tg of 60 ° C. or higher, and good adhesion and high-speed curability are also obtained. It is easy to be preferred.

  The acrylic resin having a polymerizable functional group is generally an acrylic resin having a polymerizable functional group, at least one of methyl methacrylate and an alkyl (meth) acrylate having an alcohol residue of 2 to 10 carbon atoms. And a glycidyl (meth) acrylate copolymer obtained by reacting a carboxylic acid having a polymerizable functional group with the glycidyl group, or methyl methacrylate and an alkyl having 2 to 10 carbon atoms in an alcohol residue. The methacrylic acid ester is a copolymer of at least one (meth) acrylic acid ester and a carboxylic acid having a polymerizable functional group, and the carboxylic acid group is reacted with glycidyl (meth) acrylate.

  Methyl methacrylate is preferably contained as a repeating unit in an amount of 50% by mass or more (particularly 60 to 90% by mass) in the polymer. Appropriate combination with the reactive diluent makes it easy to achieve both good adhesion and excellent curability. Alkyl (meth) acrylic acid ester having 2 to 10 carbon atoms (especially 3 to 5 carbon atoms) as an alcohol residue includes ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, Examples thereof include n-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and the like. n-butyl (meth) acrylate, isobutyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate are preferred. Further, such a (meth) acrylic acid ester is preferably contained in the polymer as a repeating unit in general in an amount of 5 to 30% by mass, particularly 10 to 30% by mass. The glycidyl (meth) acrylate or carboxylic acid having a polymerizable functional group is preferably contained in the polymer in an amount of generally 5 to 25% by mass, particularly 5 to 20% by mass as the repeating unit. The glycidyl group or carboxylic acid group of the obtained copolymer is reacted with a carboxylic acid or glycidyl (meth) acrylate having a polymerizable functional group, respectively.

  The hydroxyl group-containing acrylic resin generally includes methyl methacrylate, at least one kind of alkyl (meth) acrylic acid ester having 2 to 10 (particularly 3 to 5) carbon atoms, and alcohol residues. Is a copolymer with at least one alkyl (meth) acrylic acid ester having 2 to 4 carbon atoms having a hydroxyl group. Methyl methacrylate is preferably contained as a repeating unit in an amount of 50% by mass or more (particularly 60 to 90% by mass) in the polymer. Appropriate combination with the reactive diluent makes it easy to achieve both good adhesion and excellent curability. Alkyl (meth) acrylic acid ester having 2 to 10 carbon atoms (especially 3 to 5 carbon atoms) as an alcohol residue includes ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, Examples thereof include n-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate and the like. n-butyl (meth) acrylate, isobutyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate are preferred. Further, such a (meth) acrylic acid ester is preferably contained in the polymer as a repeating unit in general in an amount of 5 to 30% by mass, particularly 10 to 30% by mass. Examples of the alkyl (meth) acrylic acid ester having 2 to 4 carbon atoms in which the alcohol residue has a hydroxyl group include 2-hydroxyethyl methacrylate and hydroxypropyl methacrylate. In general, it is preferably contained in an amount of 5 to 25% by mass, particularly 5 to 20% by mass.

  The acrylic resin having a polymerizable functional group can be produced, for example, as follows.

  One or a plurality of (meth) acrylic monomers (preferably methyl methacrylate, at least one (meth) acrylic acid ester having an alcohol residue of 2 to 10 carbon atoms, and a glycidyl group). A known method such as solution polymerization of a compound having 1 polymerizable functional group (preferably glycidyl (meth) acrylate) or a carboxylic acid having a polymerizable functional group in the presence of a radical polymerization initiator and an organic solvent. The glycidyl group-containing acrylic resin (a) or the carboxyl group-containing acrylic resin (b), which is a copolymer, is obtained by reacting by the method described above.The mixing ratio of monomers such as (meth) acrylic monomer is the glycidyl group-containing acrylic resin. It shall be 10-45 mass% to solid content conversion total amount of (a) or carboxyl group-containing acrylic resin (b). Preferred.

  Subsequently, a carboxylic acid having a polymerizable functional group is added to the obtained glycidyl group-containing acrylic resin (a), or one glycidyl group and one polymerizable functional group are added to the obtained carboxyl group-containing acrylic resin (b). An acrylic photocurable resin (A) or an acrylic photocurable resin (B) is obtained by adding a compound (preferably glycidyl methacrylate) having heat and heating as necessary. This blending ratio is preferably blended so that the molar ratio of glycidyl group to carboxyl group is 1 / 0.9 to 1/1, and more preferably 1/1. If the glycidyl group is excessive, viscosity and gelation may occur in long-term stability, and if the carboxyl group is excessive, skin irritation increases and workability decreases. Further, in the case of 1/1, there is no residual glycidyl group, and the storage stability is remarkably improved. The reaction can be carried out by a known method in the presence of a basic catalyst, a phosphorus catalyst or the like.

  As the (meth) acrylic monomer that can be used as a main component constituting the acrylic resin that includes the above-mentioned acrylic resin having OH or a polymerizable functional group and can be used in the present invention, various kinds of acrylic acid or methacrylic acid Mention may be made of esters. Examples of various esters of acrylic acid or methacrylic acid include methyl (meth) acrylate ((meth) acrylate means acrylate and methacrylate; the same applies hereinafter), ethyl (meth) acrylate, n-propyl (meth) acrylate, n- Alkyl (meta) such as butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, lauryl (meth) acrylate, and tridecyl (meth) acrylate ) Acrylate, ethoxyethyl (meth) acrylate, alkoxyalkyl (meth) acrylate such as butoxyethyl (meth) acrylate, 2-methoxyethoxyethyl (meth) acrylate, 2-ethoxyethoxyethyl Alkoxyalkoxyalkyl (meth) acrylates such as (meth) acrylate, methoxydiethylene glycol (meth) acrylate, ethoxydiethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, butoxytriethylene glycol (meth) acrylate, methoxydipropylene glycol ( Dialkylamino such as alkoxy (poly) alkylene glycol (meth) acrylate such as (meth) acrylate, pyrenoxide adduct (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate An alkyl (meth) acrylate etc. can be mentioned. Further, an aromatic compound containing an unsaturated group (eg, styrene) may be used.

  In the present invention, as described above, as the main component of the acrylic monomer, at least one of methyl methacrylate and an alkyl (meth) acrylate having 2 to 10 carbon atoms as an alcohol residue is used. Is preferred.

  In the present invention, the polymer (preferably having a glass transition temperature of 60 ° C. or higher) preferably has a number average molecular weight of 100,000 or more, particularly 100,000 to 300,000, and a weight average molecular weight of 100,000 or more, particularly 100,000 to 300,000.

  Further, in the present invention, a polymer having both a functional group having an active hydrogen such as a hydroxyl group and a photopolymerizable functional group can be used as the polymer (preferably having a glass transition temperature of 60 ° C. or higher). As such a reactive polymer, for example, a homopolymer or a copolymer (that is, an acrylic resin) mainly obtained from the acrylic monomer, and a photopolymerizable functional group and active hydrogen are present in the main chain or side chain. It has a functional group. Therefore, such a reactive polymer includes, for example, methyl methacrylate, the one or more (meth) acrylates, and a (meth) acrylate having a functional group such as a hydroxyl group (eg, 2-hydroxyethyl (meth) acrylate). ) And the resulting polymer reacts with a functional group of the polymer and a compound having a photopolymerizable group, such as isocyanatoalkyl (meth) acrylate. In that case, the polymer which has a hydroxyl group and a photopolymerizable functional group as a functional group which has active hydrogen is obtained by adjusting and using the amount of isocyanatoalkyl (meth) acrylate so that a hydroxyl group may remain.

  Alternatively, in the above, a photopolymerizable functional group having an amino group as a functional group having active hydrogen by using a (meth) acrylate having an amino group instead of a hydroxyl group (eg, 2-aminoethyl (meth) acrylate) A containing polymer can be obtained. Similarly, a photopolymerizable functional group-containing polymer having a carboxyl group or the like as a functional group having active hydrogen can also be obtained.

  In the present invention, an acrylic resin having the photopolymerizable functional group via a urethane bond is also preferable.

  The polymer having a photopolymerizable functional group generally contains 1 to 50 mol%, particularly 5 to 30 mol% of the photopolymerizable functional group. As this photopolymerizable functional group, an acryloyl group, a methacryloyl group, and a vinyl group are preferable, and an acryloyl group and a methacryloyl group are particularly preferable.

The following are mentioned as a reactive diluent (monomer and oligomer) which has a photopolymerizable functional group contained in a photocurable composition. For example, as the (meth) acrylic monomer, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate , 2-ethylhexyl (meth) acrylate, 2-ethylhexyl polyethoxy (meth) acrylate, benzyl (meth) acrylate, isobornyl (meth) acrylate, phenyloxyethyl (meth) acrylate, tricyclodecane mono (meth) acrylate, dicyclo Pentenyloxyethyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, acryloylmorpholine, N-vinylcaprolactam, o-phenylphenyloxyethyl (meth) acryl Over DOO, 2-hydroxy-3-acryloyloxy propyl methacrylate,
Neopentyl glycol di (meth) acrylate, neopentyl glycol dipropoxy di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, tricyclodecane dimethylol di (meth) acrylate, 1,6-hexanediol di (Meth) acrylate, nonanediol di (meth) acrylate,
Glycerin diacrylate, glycerin acrylate methacrylate, glycerin dimethacrylate, trimethylolpropane diacrylate, trimethylolpropane acrylate methacrylate, trimethylolpropane dimethacrylate,
(Meth) such as trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, tris [(meth) acryloxyethyl] isocyanurate, ditrimethylolpropane tetra (meth) acrylate Acrylate monomers;
Polyol compounds (for example, ethylene glycol, propylene glycol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-ethyl-2-butyl-1, Polyols such as 3-propanediol, trimethylolpropane, diethylene glycol, dipropylene glycol, polypropylene glycol, 1,4-dimethylolcyclohexane, bisphenol A polyethoxydiol, polytetramethylene glycol, the polyols and succinic acid, maleic acid Polyester polyols which are reaction products of polybasic acids such as itaconic acid, adipic acid, hydrogenated dimer acid, phthalic acid, isophthalic acid, terephthalic acid, etc., or their acid anhydrides, and the above-mentioned polyols and ε-capro Polycaprolactone polyols which are reaction products with kuton, reaction products of the above-mentioned polyols with the above-mentioned polybasic acids or ε-caprolactone of these acid anhydrides, polycarbonate polyols, polymer polyols, etc.) and organic polyisocyanates ( For example, tolylene diisocyanate, isophorone diisocyanate, xylylene diisocyanate, diphenylmethane-4,4′-diisocyanate, dicyclopentanyl diisocyanate, hexamethylene diisocyanate, 2,4,4′-trimethylhexamethylene diisocyanate, 2,2 ′, 4 -Trimethylhexamethylene diisocyanate and the like) and hydroxyl group-containing (meth) acrylate (for example, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxy Roxybutyl (meth) acrylate, 2-hydroxy-3-phenyloxypropyl (meth) acrylate, cyclohexane-1,4-dimethylol mono (meth) acrylate, pentaerythritol tri (meth) acrylate, glycerin di (meth) acrylate, etc.) Polyurethane (meth) acrylate, which is a reaction product of
Examples thereof include (meth) acrylate oligomers such as bisphenol type epoxy (meth) acrylate which is a reaction product of bisphenol type epoxy resin such as bisphenol A type epoxy resin and bisphenol F type epoxy resin and (meth) acrylic acid. These compounds having a photopolymerizable functional group can be used alone or in combination of two or more.

  In the present invention, the mass ratio of the polymer of the photocurable composition to the reactive diluent is preferably in the range of 20:80 to 80:20, particularly 30:70 to 70:30.

  As the photopolymerization initiator contained in the photocurable composition, any known photopolymerization initiator can be used, but those having good storage stability after blending are desirable. Examples of such photopolymerization initiators include benzoin series such as acetophenone series and benzyl dimethyl ketal, thiophenone series such as benzophenone series, isopropylthioxanthone, and 2-4-diethylthioxanthone, and other special examples include methylphenylglycol. Oxylate can be used. Particularly preferably, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- (4- (methylthio) phenyl) -2-morpholinopropane-1, Examples include benzophenone. These photopolymerization initiators may contain one or two or more kinds of known and commonly used photopolymerization accelerators such as benzoic acid-based or tertiary amine-based compounds such as 4-dimethylaminobenzoic acid as required. Can be mixed and used. Moreover, it can be used by 1 type, or 2 or more types of mixture of only a photoinitiator. In general, the photocurable composition (nonvolatile content) preferably contains 0.1 to 20% by mass, particularly 1 to 10% by mass of a photopolymerization initiator.

  Among the photopolymerization initiators, examples of the acetophenone-based polymerization initiator include 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 4-t-butyl-trichloroacetophenone, diethoxyacetophenone, and 2-hydroxy-2. -Methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-dodecylphenyl) -2-hydroxy-2-methyl Propan-1-one, 4- (2-hydroxyethoxy) -phenyl (2-hydroxy-2-propyl) ketone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- (4- (methylthio) phenyl) -2 As benzophenone polymerization initiators such as morpholinopropane-1, Benzophenone, benzoyl benzoate, methyl benzoyl benzoate, 4-phenyl benzophenone, hydroxybenzophenone, 4-benzoyl-4'-methyl-diphenyl sulfide, etc. 3,3'-dimethyl-4-methoxybenzophenone may be used.

  As the acetophenone-based polymerization initiator, in particular, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- (4- (methylthio) phenyl) -2 -Morpholinopropane-1 is preferred. As the benzophenone polymerization initiator, benzophenone, benzoylbenzoic acid, and methyl benzoylbenzoate are preferable. Tertiary amine photopolymerization accelerators include triethanolamine, methyldiethanolamine, triisopropanolamine, 4,4'-dimethylaminobenzophenone, 4,4'-diethylaminobenzophenone, ethyl 2-dimethylaminobenzoate. , Ethyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate (n-butoxy), isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate and the like can be used. Particularly preferably, as the photopolymerization accelerator, ethyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate (n-butoxy), isoamyl 4-dimethylaminobenzoate, 2-ethylhexyl 4-dimethylaminobenzoate, etc. Is mentioned.

  In the present invention, the diisocyanate that can be added to the photocurable composition includes tolylene diisocyanate (TDI), isophorone diisocyanate, xylylene diisocyanate, diphenylmethane-4,4-diisocyanate, dicyclopentanyl diisocyanate, hexamethylene diisocyanate, Examples include 2,4,4′-trimethylhexamethylene diisocyanate and 2,2 ′, 4-trimethylhexamethylene diisocyanate. Polyisocyanate cyanates such as trifunctional or higher functional isocyanate compounds such as a TDI adduct of trimethylolpropane can also be used. Of these, a hexamethylene diisocyanate adduct of trimethylolpropane is preferred.

  In the present invention, the diisocyanate is preferably contained in the photocurable composition (nonvolatile content) in the range of 0.2 to 4% by mass, particularly 0.2 to 2% by mass. Appropriate crosslinking is provided to prevent the adhesive layer from seeping out, and good adhesion to the surface forming the adhesive layer is also maintained. The reaction between the compound and the polymer proceeds gradually after formation of the adhesive layer, and reacts considerably at room temperature (generally 25 ° C.) at 24 hours. It is considered that the reaction proceeds even after the application liquid of the photocurable composition for forming the adhesive layer is prepared and before the application liquid is applied. After forming the adhesive layer, it is preferable to cure it to some extent before winding it in the roll state. Therefore, if necessary, the reaction is promoted by heating during the formation of the adhesive layer or thereafter before winding in the roll state. You may let them.

  In the present invention, it is preferable to add the following thermoplastic resin and other additives to the photocurable composition as desired.

  As another additive, a silane coupling agent (adhesion promoter) can be added. As this silane coupling agent, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxy Propyltriethoxysilane, β- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-chloropropylmethoxysilane, vinyltrichlorosilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β There are (aminoethyl) -γ-aminopropyltrimethoxysilane and the like, and one of these can be used alone or two or more of them can be used in combination. As for the addition amount of these silane coupling agents, 0.01-5 mass parts is sufficient normally with respect to 100 mass parts of said polymers (solid content).

  Similarly, an epoxy group-containing compound can be added for the purpose of improving adhesiveness. Examples of the epoxy group-containing compound include triglycidyl tris (2-hydroxyethyl) isocyanurate; neopentyl glycol diglycidyl ether; 1,6-hexanediol diglycidyl ether; acrylic glycidyl ether; 2-ethylhexyl glycidyl ether; Examples thereof include phenol glycidyl ether; pt-butylphenyl glycidyl ether; adipic acid diglycidyl ester; o-phthalic acid diglycidyl ester; glycidyl methacrylate; Further, the same effect can be obtained by adding an oligomer containing an epoxy group having a molecular weight of several hundred to several thousand or a polymer having a weight average molecular weight of several thousand to several hundred thousand. The addition amount of these epoxy group-containing compounds is sufficient to be 0.1 to 20 parts by mass with respect to 100 parts by mass of the polymer (solid content), and at least one of the epoxy group-containing compounds is added alone or in combination. Can do.

  As another additive, a hydrocarbon resin can be added for the purpose of improving workability such as workability and bonding. In this case, the added hydrocarbon resin may be either a natural resin type or a synthetic resin type. These include the tackifiers described above. In natural resin systems, rosin, rosin derivatives, and terpene resins are preferably used. For rosin, gum-based resins, tall oil-based resins, and wood-based resins can be used. As the rosin derivative, rosin obtained by hydrogenation, heterogeneity, polymerization, esterification, or metal chloride can be used. As the terpene resin, a terpene phenol resin can be used in addition to a terpene resin such as α-pinene and β-pinene. In addition, dammar, corbal and shellac may be used as other natural resins. On the other hand, in the synthetic resin system, petroleum resin, phenol resin, and xylene resin are preferably used. As the petroleum resin, aliphatic petroleum resin, aromatic petroleum resin, alicyclic petroleum resin, copolymer petroleum resin, hydrogenated petroleum resin, pure monomer petroleum resin, and coumarone indene resin can be used. As the phenol resin, an alkyl phenol resin or a modified phenol resin can be used. As the xylene-based resin, a xylene resin or a modified xylene resin can be used.

  Although the addition amount of resin, such as the said hydrocarbon resin, is selected suitably, 1-20 mass parts is preferable with respect to 100 mass parts of said polymers (solid content), More preferably, it is 5-15 mass parts.

  In addition to the above additives, the photocurable composition of the present invention may contain a small amount of an ultraviolet absorber, an antioxidant, a dye, a processing aid, a polymerization inhibitor and the like.

In the present invention, the storage elastic modulus at a frequency of 1 Hz of the photocurable pressure-sensitive adhesive layer is preferably 1 × 10 ⁷ Pa or less at 25 ° C., and particularly in the range of 1 × 10 ^{4 to} 6 × 10 ⁵ Pa. preferable. Moreover, it is preferable that it is 8 * 10 < ⁴ > Pa or less in 80 degreeC, and it is especially preferable that it is the range of 1 * 10 < ⁴ > -5 * 10 < ⁵ > Pa. Thereby, accurate and quick adhesion becomes possible. Furthermore, the photocurable transfer layer of the present invention preferably has a glass transition temperature of 20 ° C. or lower. Thereby, when the photocurable pressure-sensitive adhesive layer obtained is brought into contact with the surface to which the pressure-sensitive adhesive layer is transferred, it can have flexibility to be in close contact with the surface even at room temperature. In particular, when the glass transition temperature is in the range of 15 ° C. to −50 ° C., and further in the range of 0 ° C. to −40 ° C., the adhesiveness becomes high. If the glass transition temperature is too high, a high pressure and a high pressure are required at the time of bonding, leading to a decrease in workability. If it is too low, sufficient hardness after curing cannot be obtained.

Moreover, in this invention, it is preferable that the photocurable transfer layer is designed so that the glass transition temperature after 300mJ / cm < ² > ultraviolet irradiation may be 65 degreeC or more. The pressure-sensitive adhesive layer can be cured by short-time ultraviolet irradiation, and strong adhesiveness can be ensured.

  The photocurable pressure-sensitive adhesive sheet of the present invention is obtained by uniformly mixing the components of the above-mentioned photocurable composition and kneading with an extruder, a roll, etc., and then by a film forming method such as a calendar, roll, T-die extrusion, inflation, etc. And can be produced by forming a film on the surface of the release sheet. More preferable method for forming a photocurable pressure-sensitive adhesive layer of the present invention is to uniformly mix and dissolve each constituent component in a good solvent, and use this solution as a flow coating method, a roll coating method, a gravure roll method, a Myer bar method, a lip die coating method. It is a method of forming a film by coating on a release sheet by, for example, and drying a solvent.

  Moreover, it is preferable that the thickness of a photocurable adhesive sheet shall be 1-1000 micrometers, and also 5-500 micrometers. Particularly preferred is 5 to 300 μm (preferably 150 μm or less). If it is thinner than 1 μm, the sealing performance is inferior. On the other hand, if it is thicker than 1000 μm, there may be a problem in storage, assembly, and the like.

  The thickness of the photocurable pressure-sensitive adhesive layer is not particularly limited, and can be set according to the thickness of the target pressure-sensitive adhesive layer. If it is too thick, there is a possibility that the adhesive layer may protrude beyond the necessary portion, so generally 1 to 300 μm, particularly 3 to 100 μm is preferable.

In the case of curing the photocurable adhesive layer formed by the method of the present invention, many light sources that emit light in the ultraviolet to visible region can be used as the light source, such as ultrahigh pressure, high pressure, low pressure mercury lamp, chemical lamp, xenon lamp, Examples include halogen lamps, Mercury halogen lamps, carbon arc lamps, incandescent lamps, and laser light. The irradiation time is not generally determined depending on the type of the lamp and the intensity of the light source, but is about 0.1 to several tens of seconds, preferably 0.5 to several seconds. The ultraviolet irradiation amount is preferably 300 mJ / cm ² or more.

  Moreover, in order to accelerate hardening, a member on which an adhesive layer has been formed in advance may be heated to 30 to 80 ° C. and irradiated with ultraviolet rays.

  The following examples further illustrate the present invention.

[Examples 1 and 2 and Comparative Examples 1 to 5]
<Production of photocurable pressure-sensitive adhesive sheet>
(Preparation of polymer A having hydroxyl groups)
The following formulation:
Methyl methacrylate 74.6 parts by mass n-butyl methacrylate 13.2 parts by mass 2-hydroxyethyl methacrylate 12.1 parts by mass AIBN 5.0 parts by mass Toluene 50.0 parts by mass Ethyl acetate 50.0 parts by mass While stirring, the polymerization was started by heating to 70 ° C. and stirred at this temperature for 8 hours to obtain a polymer A (acrylic resin) having a hydroxyl group having a hydroxyl group in the side chain. The solid content was adjusted to 36% by mass (polymer A solution). The obtained polymer A had a Tg of 73 ° C. and a weight average molecular weight of 110,000.

(Preparation of photocurable adhesive sheet)
As an additive for controlling the thixotropic index (η), a tackifier (aromatic modified terpene resin YS resin TO125 (manufactured by Yashara Chemical Co.)) and fine particles (hydrophobic fumed silica AEROSIL R202 (manufactured by Nippon Aerosil Co., Ltd.)) are used. Thus, a photocurable pressure-sensitive adhesive sheet was prepared, that is, a mixture of each formulation of Examples 1 and 2 and Comparative Examples 1 to 5 shown in Table 1 was uniformly dissolved and kneaded, and a release sheet (trade name A31, Teijin DuPont Films, Inc .; 300 mm wide, 300 m long, 50 μm thick), a photocurable adhesive layer with a dry thickness of 25 μm is formed, the same release sheet is pasted on the opposite side of the sheet, and a roll A full-edge type roll (diameter 260 mm) of a photocurable pressure-sensitive adhesive sheet was obtained, and the thixotropy index (η) of the photocurable composition of each photocurable pressure-sensitive adhesive layer is shown in Table 1. In the case of a tackifier, the addition of 2.2% by mass relative to the photocurable composition, and in the case of fine particles, the addition of 1.3% by mass, the thixotropic index (η) is 1 A large photocurable composition could be obtained.

<Evaluation of transferability of adhesive layer>
Using the photocurable transfer sheets of Examples 1 and 2 and Comparative Examples 1 to 5, the step of forming an adhesive layer on the convex end surface of the surface having irregularities shown in FIG. 4 was performed. That is, the pressure-sensitive adhesive layer of each photocurable pressure-sensitive adhesive sheet is affixed to the surface of the substrate having a concavo-convex pattern by pressing, and then the release sheet is removed from the surface having the concavo-convex, and the pressure-sensitive adhesive layer is formed on the convex end surface. Transcribed. The transferability of the pressure-sensitive adhesive layer was visually evaluated. The case where the pressure-sensitive adhesive layer was accurately formed only on the end face of the convex portion was indicated by “◯”, and the case where the pressure-sensitive adhesive layer protruded from the concave portion was indicated by “X”.

  The results are shown in Table 1.

As shown in Table 1, transferability was poor for Comparative Examples 1 to 5 in which the thixotropic index (η) of the photocurable composition of the photocurable adhesive layer was lower than 1. On the other hand, Examples 1 and 2 in which the thixotropy index (η) of the photocurable composition was greater than 1 showed good transferability, and an adhesive layer could be accurately formed only on the end face of the convex portion. .

  In addition, this invention is not limited to the structure and Example of said embodiment, A various deformation | transformation is possible within the range of the summary of invention.

  ADVANTAGE OF THE INVENTION According to this invention, when manufacturing the board | substrate which has unevenness | corrugations on the surface, such as a board | substrate for image display panels of an electronic paper display, reduction of a defective rate and reduction of manufacturing cost can be aimed at.

10, 20 Photocurable adhesive sheet 11, 21 Photocurable adhesive layer 11c, 21c Photocurable adhesive layer (after transfer)
12, 13, 22, 23 Release sheet 12a, 13a Release layer 12b, 13b Polymer film 14 Substrate 15, 25 Convex end face 16 Concave surface 27 Conveyor 28a Feed roll 28b, 28d Winding roll 28c Guide roll 36a
29 Pressing roll

Claims (11)

A photocurable pressure-sensitive adhesive sheet having a photocurable pressure-sensitive adhesive layer made of an adhesive photocurable composition,
A release sheet is provided on one or both surfaces of the photocurable adhesive layer,
The thixotropic index (η) of the photocurable composition is represented by the following formula:

[However, (G ^′ _{0.01 Hz} ) indicates storage elastic modulus at room temperature and frequency 0.01 Hz, and (G ^′ _{46.4 Hz} ) indicates storage elastic modulus at normal temperature and frequency 46.4 Hz. ]
And a photocurable pressure-sensitive adhesive sheet, wherein η> 1. The photocurable pressure-sensitive adhesive sheet according to claim 1, wherein the photocurable composition contains a tackifier having a solubility parameter of 8.5 to 9.5 (J / cm ³ ) ^1/2 .   The photocurable pressure-sensitive adhesive sheet according to claim 2, wherein the tackifier is at least one compound selected from the group consisting of terpene resins, modified terpene resins, terpene phenol resins, and hydrogenated terpene resins. The photocurable pressure-sensitive adhesive sheet according to claim 2 or 3, wherein the content of the tackifier is 0.9 to 3.5% by mass with respect to the photocurable composition.   The photocurable pressure-sensitive adhesive sheet according to any one of claims 1 to 4, wherein the photocurable composition contains fine particles having an average particle diameter of 1 to 300 nm.   The photocurable pressure-sensitive adhesive sheet according to claim 5, wherein the fine particles are transparent fine particles.   The photocurable pressure-sensitive adhesive sheet according to claim 6, wherein the transparent fine particles are silica fine particles.   The photocurable pressure-sensitive adhesive sheet according to any one of claims 5 to 7, wherein the content of the fine particles is 0.4 to 2.2 mass% with respect to the photocurable composition.   The photocurable pressure-sensitive adhesive sheet according to any one of claims 1 to 8, wherein the release sheet comprises a polymer film and a release layer provided on the surface thereof so as to come into contact with the photocurable pressure-sensitive adhesive layer. The following steps:
(1) When the photocurable pressure-sensitive adhesive sheet according to any one of claims 1 to 9 has a release sheet on both sides, a step of removing one of the release sheets;
(2) A step of bringing the photocurable pressure-sensitive adhesive layer of the photocurable pressure-sensitive adhesive sheet into contact with and pressing the convex end surface of the surface having irregularities;
(3) A step of forming an adhesive layer on the end face of the convex portion by removing the release sheet of the photocurable adhesive sheet from the surface having the irregularities;
A method for forming a photocurable pressure-sensitive adhesive layer.   The method according to claim 10, wherein the uneven surface is a surface of an image display panel substrate.

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