JP6389198B2 - Adhesive sheet, display body, and production method thereof - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive sheet for bonding display body constituent members, a display body formed by bonding display body constituent members, and a method for producing them.

  Various mobile electronic devices such as mobile phones, smartphones, and tablet terminals in recent years include display bodies (displays) using display body modules having liquid crystal elements, light emitting diodes (LED elements), organic electroluminescence (organic EL) elements, and the like. I have.

  In such a display, a protective panel is usually provided on the surface side of the display module. A gap is provided between the protection panel and the display module so that the deformed protection panel does not hit the display module even when the protection panel is deformed by an external force.

  However, if there is a gap as described above, that is, an air layer, the difference in refractive index between the protective panel and the air layer, and the reflection loss of light due to the difference in refractive index between the air layer and the display module is large. There is a problem that the image quality deteriorates.

  Therefore, it has been proposed to improve the image quality of the display by filling the gap between the protective panel and the display module with an adhesive layer. However, a frame-like printed layer may exist as a step on the display module side of the protective panel. If the pressure-sensitive adhesive layer does not follow the step, the pressure-sensitive adhesive layer floats in the vicinity of the step, thereby causing light reflection loss. For this reason, the pressure-sensitive adhesive layer is required to have a step following ability.

  In order to solve the above problems, Patent Document 1 includes a (meth) acrylic copolymer of a monomer containing a (meth) acrylic acid ester having an ultraviolet crosslinkable site (benzophenone structure), before and after ultraviolet crosslinking. An ultraviolet crosslinkable pressure-sensitive adhesive sheet having a specified storage elastic modulus is disclosed. Such an ultraviolet-crosslinkable pressure-sensitive adhesive sheet is one that increases the cohesive force by advancing the crosslinking reaction by performing ultraviolet irradiation after bonding the adherend. The ultraviolet crosslinkable pressure-sensitive adhesive sheet has a low storage elastic modulus at the stage of being attached to the adherend, that is, before the ultraviolet crosslink, and therefore easily follows the level difference of the adherend.

JP 2011-184582 A

  However, since the (meth) acrylic copolymer used in the UV-crosslinkable pressure-sensitive adhesive sheet of Patent Document 1 has a low crosslinking density and cohesion before UV-crosslinking, the UV-crosslinkable pressure-sensitive adhesive sheet is cut. The (meth) acrylic copolymer may adhere to the blade, or the (meth) acrylic copolymer may ooze out from the UV-crosslinkable pressure-sensitive adhesive sheet during storage of the UV-crosslinkable pressure-sensitive adhesive sheet. It was. Thus, the ultraviolet crosslinkable pressure-sensitive adhesive sheet of Patent Document 1 has a low film strength.

  On the other hand, when an ultraviolet curable pressure sensitive adhesive containing a general photopolymerization initiator is used in the ultraviolet crosslinkable pressure sensitive adhesive sheet as described above, the ultraviolet curable pressure sensitive adhesive is not sufficiently cured depending on the type of the protective panel. There were cases where problems occurred under durable conditions. For example, when high-temperature and high-humidity conditions are applied, bubbles may be generated in the vicinity of the level difference, or outgas may be generated from the plastic plate, which is a protective panel, and blisters such as bubbles, floating and peeling may occur. .

  The present invention has been made in view of such a situation, and is a pressure-sensitive adhesive sheet having a relatively high coating strength of the pressure-sensitive adhesive layer and excellent in both step followability and blister resistance, step followability and blister resistance. It aims at providing the display body which is excellent in both property, and those manufacturing methods.

  In order to achieve the above object, first, the present invention is a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer for laminating one display body constituent member and another display body constituent member, wherein the adhesive The agent layer has a crosslinked structure composed of the (meth) acrylic acid ester copolymer (A) and the thermal crosslinking agent (B), an ultraviolet curable component (C), and a concentration of 0.1% by mass. A pressure-sensitive adhesive sheet comprising an ultraviolet curable pressure-sensitive adhesive containing a photopolymerization initiator (D) having an absorbance at a wavelength of 380 nm in an acetonitrile solution of 0.3 or more is provided (Invention 1).

  In the pressure-sensitive adhesive sheet according to the invention (Invention 1), the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is thermally cross-linked, and thus the film strength of the pressure-sensitive adhesive layer is relatively high. Moreover, even when one display body structural member and / or another display body structural member contains a ultraviolet absorber by containing a specific photoinitiator (D), an adhesive layer becomes It is sufficiently cured by irradiation with ultraviolet rays, and has excellent step following ability and blister resistance.

  In the said invention (invention 1), it is preferable that the gel fraction of the said adhesive is 30% or more and 70% or less (invention 2).

  In the said invention (invention 1 and 2), it is preferable that at least one of the said 1 display body structural member and the said other display body structural member contains a ultraviolet absorber (invention 3).

  In the said invention (invention 1-3), it is preferable that the said one display body structural member has a level | step difference at the surface at the side to be bonded at least (invention 4).

  In the said invention (invention 1-4), the said adhesive sheet is equipped with two peeling sheets, and the said adhesive layer is clamped by the said peeling sheet so that the peeling surface of the said two peeling sheets may be contact | connected. (Invention 5)

  2ndly this invention is a manufacturing method of the adhesive sheet provided with the adhesive layer for bonding one display body structural member and another display body structural member, Comprising: (meth) acrylic acid ester co A polymer (A), a thermal crosslinking agent (B), an ultraviolet curable component (C), and a photopolymerization initiator having an absorbance at a wavelength of 380 nm in an acetonitrile solution having a concentration of 0.1% by mass of 0.3 or more ( A method for producing a pressure-sensitive adhesive sheet, characterized in that an ultraviolet-curable pressure-sensitive adhesive layer is formed by applying a pressure-sensitive adhesive composition containing D) and thermally cross-linking (Invention 6).

  Thirdly, the present invention relates to a post-curing pressure-sensitive adhesive layer that bonds together one display body constituent member, another display body constituent member, and the one display body constituent member and the other display body constituent member. The cured adhesive layer has a crosslinked structure composed of a (meth) acrylic acid ester copolymer (A) and a thermal crosslinking agent (B), and is ultraviolet curable. It consists of a pressure-sensitive adhesive containing a cured product of component (C) and a photopolymerization initiator (D) having an absorbance at a wavelength of 380 nm in an acetonitrile solution having a concentration of 0.1% by mass of 0.3 or more. A display body is provided (Invention 7). In addition, the post-curing pressure-sensitive adhesive layer in the present invention has already undergone the curing reaction of the ultraviolet curable component (C) by the photopolymerization initiator (D), and the gel fraction does not exceed even if further ultraviolet irradiation is performed. A pressure-sensitive adhesive layer having a small rising width (preferably about 5% or less).

  Fourthly, the present invention provides a post-curing pressure-sensitive adhesive layer that bonds together one display body constituent member, another display body constituent member, the one display body constituent member, and the other display body constituent member. The cured adhesive layer has a crosslinked structure composed of a (meth) acrylic acid ester copolymer (A) and a thermal crosslinking agent (B), and is ultraviolet curable. Provided is a display body comprising an adhesive containing a cured product of component (C), wherein the gel fraction of the adhesive layer after curing is 40% or more and 95% or less (Invention 8).

  5thly this invention produces the laminated body formed by bonding one display body structural member and another display body structural member through the adhesive layer of the said adhesive sheet (invention 1-5), Provided is a method for producing a display body, wherein the pressure-sensitive adhesive layer of the laminate is irradiated with ultraviolet rays to cure the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive layer after curing (Invention 9).

  The pressure-sensitive adhesive sheet according to the present invention has a relatively high coating strength of the pressure-sensitive adhesive layer, and is excellent in both step followability and blister resistance. Moreover, the display body according to the present invention is excellent in both the step followability and the blister resistance. Furthermore, according to the method according to the present invention, these pressure-sensitive adhesive sheets and display bodies can be produced.

It is sectional drawing of the adhesive sheet which concerns on one Embodiment of this invention. It is sectional drawing of the laminated body which concerns on one Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
[Adhesive sheet]
The adhesive sheet which concerns on this embodiment is an adhesive sheet provided with the adhesive layer for bonding one display body structural member and another display body structural member. A display body and a display body structural member are mentioned later.

  As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 according to this embodiment as an example includes the two release sheets 12 a and 12 b and the two release sheets 12 a and 12 b so as to be in contact with the release surfaces of the two release sheets 12 a and 12 b. It is comprised from the adhesive layer 11 pinched | interposed into peeling sheet 12a, 12b. In addition, the release surface of the release sheet in this specification refers to a surface having peelability in the release sheet, and includes both a surface that has been subjected to a release treatment and a surface that exhibits peelability without being subjected to a release treatment. .

1. Pressure-sensitive adhesive layer The pressure-sensitive adhesive layer 11 has a crosslinked structure composed of a (meth) acrylic acid ester copolymer (A) and a thermal crosslinking agent (B), an ultraviolet curable component (C), and a concentration. It consists of an ultraviolet curable pressure-sensitive adhesive containing a photopolymerization initiator (D) having an absorbance at a wavelength of 380 nm in a 0.1% by mass acetonitrile solution of 0.3 or more. In other words, the pressure-sensitive adhesive layer 11 comprises a (meth) acrylic acid ester copolymer (A), a thermal crosslinking agent (B), an ultraviolet curable component (C), and an acetonitrile solution having a concentration of 0.1% by mass. UV-cured by thermally crosslinking a pressure-sensitive adhesive composition (hereinafter also referred to as “pressure-sensitive adhesive composition P”) containing a photopolymerization initiator (D) having an absorbance at a wavelength of 380 nm of 0.3 or more. It consists of sex adhesive. In the present specification, (meth) acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms.

  As described above, the pressure-sensitive adhesive layer 11 in the pressure-sensitive adhesive sheet 1 is composed of a pressure-sensitive adhesive obtained by thermally cross-linking the pressure-sensitive adhesive composition P, and the pressure-sensitive adhesive is thermally cross-linked with the (meth) acrylic acid ester copolymer (A). It has a crosslinked structure composed of the agent (B). On the other hand, the ultraviolet curable component (C) has not been cured yet and is present in the pressure-sensitive adhesive as it is blended in the pressure-sensitive adhesive composition P. The ultraviolet curable component (C) is polymerized and cured when the pressure-sensitive adhesive layer 11 is irradiated with ultraviolet rays when the pressure-sensitive adhesive sheet 1 is used (after bonding the adherend).

  In the pressure-sensitive adhesive sheet 1 according to the present embodiment, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 is thermally cross-linked, and has a certain degree of cross-linking density and a predetermined cohesive force. high. Therefore, for example, when the pressure-sensitive adhesive sheet is cut or the like, problems such as adhesion of the pressure-sensitive adhesive to the blade are suppressed. In addition, the adhesive is prevented from oozing out from the adhesive layer 11 when the adhesive sheet 1 is stored.

  In addition, since the pressure-sensitive adhesive layer 11 in the pressure-sensitive adhesive sheet 1 according to the present embodiment is relatively soft before curing by ultraviolet irradiation, the pressure-sensitive adhesive layer when the pressure-sensitive adhesive sheet 1 is attached to a display member constituting member having a level difference. 11 easily follows the step, and the occurrence of gaps, floats, etc. in the vicinity of the step is suppressed.

  On the other hand, when the pressure-sensitive adhesive sheet 1 according to the present embodiment is used, one display body constituent member is bonded to the other display body constituent member by the adhesive layer 11 of the pressure-sensitive adhesive sheet 1. Alternatively, the pressure-sensitive adhesive layer 11 is irradiated with ultraviolet rays through another display member constituting member, and the pressure-sensitive adhesive layer 11 is cured to be a pressure-sensitive adhesive layer after curing (the pressure-sensitive adhesive layer 11 ′ after curing in FIG. 2 described later). And As a result, even when the obtained laminate (display body) is placed under high temperature and high humidity conditions, for example, 85 ° C. and 85% RH for 72 hours, bubbles, floating, peeling, etc. are generated near the step. Is suppressed. Furthermore, generation | occurrence | production of blisters, such as a bubble in the interface of a display body structural member and the adhesive layer after hardening, a float, and peeling, is also suppressed. That is, the pressure-sensitive adhesive sheet 1 according to the present embodiment is excellent in step followability and blister resistance under high temperature and high humidity conditions in addition to the initial step followability.

  Here, in the case where the one display member constituting member and / or the other display member constituting member contains an ultraviolet absorber, a conventional photopolymerization initiator such as 1-hydroxycyclohexyl phenyl ketone is used as the adhesive. In addition, when the pressure-sensitive adhesive layer is irradiated with ultraviolet rays through the one display member constituting member or the other display member constituting member, the ultraviolet light having a wavelength for cleaving the photopolymerization initiator is changed to ultraviolet rays in the display member constituting member. Absorbed by the absorbent, cleavage of the photopolymerization initiator is inhibited. As a result, the curing reaction of the ultraviolet curable component does not proceed well, and the pressure-sensitive adhesive layer is not sufficiently cured. Thereby, an adhesive layer becomes inferior to the level | step difference followability and blister-proof property on high temperature, high humidity conditions. On the other hand, the pressure-sensitive adhesive layer 11 in the pressure-sensitive adhesive sheet 1 according to this embodiment contains a photopolymerization initiator (D) having an absorbance at a wavelength of 380 nm in an acetonitrile solution having a concentration of 0.1% by mass of 0.3 or more. . In this case, even if the pressure-sensitive adhesive layer 11 is irradiated with ultraviolet rays through the display member constituting member containing the ultraviolet absorber, ultraviolet rays having a wavelength (long wavelength) for cleaving the photopolymerization initiator (D) are displayed. The photopolymerization initiator (D) is cleaved without any problem without being absorbed by the ultraviolet absorber in the body constituting member. As a result, the curing reaction of the ultraviolet curable component (C) proceeds well, and the pressure-sensitive adhesive layer 11 is sufficiently cured. Thereby, the obtained laminated body (display body) becomes excellent in the level | step difference followability and blister resistance under high temperature, high humidity conditions. That is, according to the pressure-sensitive adhesive sheet 1 according to the present embodiment, even when one display member constituting member and / or another display member constituting member contains an ultraviolet absorber, the step following property under high temperature and high humidity conditions and Excellent blister resistance.

(1) (Meth) acrylic acid ester copolymer (A)
The (meth) acrylic acid ester copolymer (A) contains a reactive group-containing monomer having in its molecule a reactive group that reacts with the thermal crosslinking agent (B) as a monomer unit constituting the polymer. preferable. The reactive group derived from the reactive group-containing monomer reacts with the thermal crosslinking agent (B) to form a crosslinked structure (three-dimensional network structure), and the pressure-sensitive adhesive layer 11 having a relatively high film strength is obtained.

  Examples of the reactive group-containing monomer include a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxy group in the molecule (carboxy group-containing monomer), and a monomer having an amino group in the molecule (amino group-containing monomer). Etc.) are preferred. Among these, a hydroxyl group-containing monomer that is excellent in reactivity with the thermal cross-linking agent (B) and has little adverse effect on the adherend is particularly preferable. Moreover, even if the weight average molecular weight of the (meth) acrylic acid ester copolymer (A) is relatively low, a carboxy group-containing monomer is preferable from the viewpoint of exhibiting a desired cohesive force.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (meth And (meth) acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylate. Among these, from the viewpoint of the reactivity of the hydroxyl group in the resulting (meth) acrylic acid ester copolymer (A) with the thermal crosslinking agent (B) and the copolymerizability with other monomers, (meth) acrylic acid 2- Hydroxyethyl and 4-hydroxybutyl (meth) acrylate are preferred, and 2-hydroxyethyl (meth) acrylate is particularly preferred. These may be used alone or in combination of two or more.

  Examples of the carboxy group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. Of these, acrylic acid is preferred from the viewpoint of the reactivity of the resulting (meth) acrylic acid ester copolymer (A) with the thermal crosslinking agent (B) of the carboxy group and the copolymerizability with other monomers. These may be used alone or in combination of two or more.

  Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, n-butylaminoethyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester copolymer (A) preferably contains a hydroxyl group-containing monomer as a lower limit of 3% by mass or more, particularly 10% by mass or more, as a monomer unit constituting the polymer. It is preferable to contain 15% by mass or more. The (meth) acrylic acid ester copolymer (A) preferably contains a hydroxyl group-containing monomer as an upper limit value of 35% by mass or less, particularly 30% by mass or less, as a monomer unit constituting the polymer. It is preferable to contain, and it is preferable to contain 25 mass% or less. When the (meth) acrylic acid ester copolymer (A) contains a hydroxyl group-containing monomer in the above amount as a monomer unit, a good cross-linked structure is formed in the resulting pressure-sensitive adhesive, and the pressure-sensitive adhesive layer 11 has a relatively high film strength. As a result, a predetermined amount of hydroxyl groups remain in the pressure-sensitive adhesive. A hydroxyl group is a hydrophilic group, and when such a hydrophilic group is present in a pressure-sensitive adhesive, even if the pressure-sensitive adhesive is placed under a high temperature and high humidity condition, it penetrates into the pressure sensitive adhesive under the high temperature and high humidity condition. As a result, the whitening of the pressure-sensitive adhesive when it is returned to room temperature and normal humidity is suppressed (excellent moisture and heat whitening resistance).

  When the (meth) acrylic acid ester copolymer (A) contains a carboxy group-containing monomer as a monomer unit constituting the polymer, the (meth) acrylic acid ester copolymer (A) is the carboxy group-containing monomer. Is preferably contained in an amount of 5% by mass or more as a lower limit, particularly preferably 7% by mass or more, and more preferably 10% by mass or more. The (meth) acrylic acid ester copolymer (A) preferably contains a carboxy group-containing monomer as an upper limit of 30% by mass or less, particularly 20% by mass or less, as a monomer unit constituting the polymer. It is preferable to contain, Furthermore, it is preferable to contain 15 mass% or less. When the (meth) acrylic acid ester copolymer (A) contains a carboxy group-containing monomer in the above amount as a monomer unit, a good cross-linked structure is formed in the resulting pressure-sensitive adhesive, and the pressure-sensitive adhesive layer has a relatively high film strength. 11 is obtained.

  The (meth) acrylic acid ester copolymer (A) preferably does not contain a carboxy group-containing monomer as a monomer unit constituting the polymer. Since the carboxy group is an acid component, by not containing a carboxy group-containing monomer, there is a problem that causes a defect due to an acid on the adhesive application target, for example, a transparent conductive film such as tin-doped indium oxide (ITO) or a metal film. Even when it exists, those defects (corrosion, resistance value change, etc.) due to the acid can be suppressed. However, it is allowed to contain a predetermined amount of the carboxy group-containing monomer to such an extent that such a problem does not occur. Specifically, in the (meth) acrylic acid ester copolymer (A), as a monomer unit, a carboxy group-containing monomer is less than 5% by mass, preferably 2% by mass or less, particularly preferably 0.1% by mass or less. It is allowed to be contained in an amount of.

  The (meth) acrylic acid ester copolymer (A) contains a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. Can be expressed. Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic acid n-. Butyl, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, (meth) acrylic acid Examples include n-dodecyl, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. Among these, from the viewpoint of further improving the adhesiveness, (meth) acrylic acid esters having 1 to 8 carbon atoms in the alkyl group are preferable, and (meth) acrylic acid n-butyl or (meth) acrylic acid 2-ethylhexyl is particularly preferable. . In addition, these may be used independently and may be used in combination of 2 or more type.

  The (meth) acrylic acid ester copolymer (A) may contain 40% by mass or more of a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms as the monomer unit constituting the polymer. The content is preferably 50% by mass or more, more preferably 60% by mass or more. If it contains 40 mass% or more of (meth) acrylic-acid alkylester, suitable adhesiveness can be provided to a (meth) acrylic-ester copolymer (A). Moreover, it is preferable to contain 90 mass% or less of the (meth) acrylic acid alkyl ester whose carbon number of an alkyl group is 1-20, It is preferable to contain especially 80 mass% or less, Furthermore, 70 mass% or less is contained. Is preferred. By setting the content of the (meth) acrylic acid alkyl ester to 90% by mass or less, a desired amount of other monomer components can be introduced into the (meth) acrylic acid ester copolymer (A).

  The (meth) acrylic acid ester copolymer (A) also preferably contains a monomer having an alicyclic structure in the molecule (an alicyclic structure-containing monomer) as a monomer unit constituting the copolymer. Since the alicyclic structure-containing monomer is bulky, it is presumed that the presence of the alicyclic structure-containing monomer in the polymer increases the distance between the polymers, and the resulting pressure-sensitive adhesive can be made excellent in flexibility. . Therefore, the (meth) acrylic acid ester polymer (A) has an alicyclic structure-containing monomer as a constituent monomer unit, whereby the pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition P has an initial step following property. It will be excellent.

  The carbocyclic ring of the alicyclic structure in the alicyclic structure-containing monomer may have a saturated structure or may have an unsaturated bond in part. The alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as a bicyclic ring or a tricyclic ring. From the viewpoint of increasing the distance between the obtained (meth) acrylic acid ester copolymer (A) and effectively exhibiting the flexibility of the pressure-sensitive adhesive, the alicyclic structure is a polycyclic alicyclic structure. (Polycyclic structure) is preferable. Furthermore, considering the compatibility between the (meth) acrylic acid ester copolymer (A) and other components, the polycyclic structure is particularly preferably bicyclic to tetracyclic. In addition, from the viewpoint of effectively exerting the flexibility of the pressure-sensitive adhesive as described above, the carbon number of the alicyclic structure (refers to all the carbon numbers of the portion forming the ring, and a plurality of rings are independent. The total number of carbon atoms) is usually preferably 5 or more, particularly preferably 7 or more. On the other hand, the upper limit of the number of carbon atoms in the alicyclic structure is not particularly limited, but it is preferably 15 or less and particularly preferably 10 or less from the viewpoint of compatibility as described above.

  Examples of the alicyclic structure include a cyclohexyl skeleton, dicyclopentadiene skeleton, adamantane skeleton, isobornyl skeleton, cycloalkane skeleton (cycloheptane skeleton, cyclooctane skeleton, cyclononane skeleton, cyclodecane skeleton, cycloundecane skeleton, cyclododecane skeleton, etc.) , Cycloalkene skeleton (cycloheptene skeleton, cyclooctene skeleton, etc.), norbornene skeleton, norbornadiene skeleton, cubane skeleton, basketn skeleton, Hausan skeleton, spiro skeleton, etc. are included, and among them, more excellent durability is exhibited. Those containing a dicyclopentadiene skeleton (carbon number of alicyclic structure: 10), adamantane skeleton (carbon number of alicyclic structure: 10) or isobornyl skeleton (carbon number of alicyclic structure: 7) are particularly preferable. Contains isobornyl skeleton Preference is.

  As the alicyclic structure-containing monomer, a (meth) acrylic acid ester monomer containing the above skeleton is preferable. Specifically, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, (meth) Examples include adamantyl acrylate, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and dicyclopentenyloxyethyl (meth) acrylate. Among them, (meth) acryl that exhibits superior durability. Dicyclopentanyl acid, adamantyl (meth) acrylate or isobornyl (meth) acrylate is preferred, and isobornyl (meth) acrylate is particularly preferred. These may be used individually by 1 type and may be used in combination of 2 or more type.

  When the (meth) acrylic acid ester copolymer (A) contains an alicyclic structure-containing monomer as a monomer unit constituting the polymer, the (meth) acrylic acid ester copolymer (A) is an alicyclic ring. It is preferable to contain 5 mass% or more of a formula structure containing monomer, It is preferable to contain especially 8 mass% or more, Furthermore, it is preferable to contain 10 mass% or more. Further, the (meth) acrylic acid ester copolymer (A) preferably contains 40% by mass or less of an alicyclic structure-containing monomer as a monomer unit constituting the polymer, particularly 30% by mass or less. It is preferable to contain 20% by mass or less. When the content of the alicyclic structure-containing monomer is in the above range, the initial step following property of the obtained pressure-sensitive adhesive becomes more excellent.

  The (meth) acrylic acid ester copolymer (A) also preferably contains a monomer having a nitrogen atom in the molecule (nitrogen atom-containing monomer) as a monomer unit constituting the copolymer. In addition, the amino group containing monomer illustrated as a reactive group containing monomer shall be remove | excluded from the said nitrogen atom containing monomer. By allowing the nitrogen atom-containing monomer to be present in the polymer as a constituent unit, the reaction between the acrylate copolymer (A) and the thermal crosslinking agent (B) is promoted, or the adhesive is polarized to provide adhesion. The cohesive strength of the agent itself can be increased.

  Examples of the nitrogen atom-containing monomer include a monomer having a tertiary amino group, a monomer having an amide group, a monomer having a nitrogen-containing heterocycle, and the like. Among these, a monomer having a nitrogen-containing heterocycle is preferable.

  Examples of the monomer having a nitrogen-containing heterocyclic ring include N- (meth) acryloylmorpholine, N-vinyl-2-pyrrolidone, N- (meth) acryloylpyrrolidone, N- (meth) acryloylpiperidine, N- (meth) acryloyl. Pyrrolidine, N- (meth) acryloylaziridine, aziridinylethyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc. Among them, N- (meth) acryloylmorpholine exhibiting more excellent adhesive strength is preferable, and N-acryloylmorpholine is particularly preferable.

Examples of the nitrogen atom-containing monomer other than the above-mentioned monomer having a nitrogen-containing heterocyclic ring include (meth) acrylamide, N-methyl (meth) acrylamide, N-methylol (meth) acrylamide, N-tert-butyl (meth) ) Acrylamide, N, N-dimethyl (meth) acrylamide, N, N-ethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-phenyl (meth) acrylamide , Dimethylaminopropyl (meth) acrylamide, N-vinylcaprolactam, dimethylaminoethyl (meth) acrylate, and the like can also be used.
The above nitrogen atom containing monomers may be used individually by 1 type, and may be used in combination of 2 or more type.

  When the (meth) acrylic acid ester copolymer (A) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, the (meth) acrylic acid ester copolymer (A) is a nitrogen atom-containing monomer. Is preferably contained in an amount of 1% by mass or more, particularly preferably 2% by mass or more, and more preferably 5% by mass or more. Further, the (meth) acrylic acid ester copolymer (A) preferably contains 40% by mass or less of a nitrogen atom-containing monomer as a monomer unit constituting the polymer, and particularly preferably contains 25% by mass or less. More preferably, it is preferably contained in an amount of 15% by mass or less. When the content of the nitrogen atom-containing monomer is within the above range, the cohesive force of the obtained pressure-sensitive adhesive is effectively improved.

  The (meth) acrylic acid ester copolymer (A) may contain other monomers as monomer units constituting the polymer, if desired. The other monomer is preferably a monomer that does not contain a reactive functional group. Examples of such other monomers include (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

  The polymerization aspect of the (meth) acrylic acid ester copolymer (A) may be a random copolymer or a block copolymer.

  The weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 100,000 or more as a lower limit, particularly preferably 200,000 or more, and more preferably 300,000 or more. When the lower limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is not less than the above, the resulting adhesive has higher film strength. The weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 900,000 or less as an upper limit, particularly preferably 800,000 or less, and more preferably 700,000 or less. preferable. When the upper limit of the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is not more than the above, the step following property of the pressure-sensitive adhesive obtained is more excellent. In addition, the weight average molecular weight in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

  In the adhesive composition P, the (meth) acrylic ester copolymer (A) may be used alone or in combination of two or more.

(2) Thermal crosslinking agent (B)
When the pressure-sensitive adhesive composition P containing the thermal crosslinking agent (B) is heated, the thermal crosslinking agent (B) crosslinks the (meth) acrylic acid ester copolymer (A) to form a three-dimensional network structure. Thereby, the adhesive layer 11 with comparatively high film strength is obtained.

  As said thermal crosslinking agent (B), what is necessary is just to react with the reactive group which (meth) acrylic acid ester copolymer (A) has, for example, isocyanate type crosslinking agent, epoxy type crosslinking agent, amine type Crosslinking agent, melamine crosslinking agent, aziridine crosslinking agent, hydrazine crosslinking agent, aldehyde crosslinking agent, oxazoline crosslinking agent, metal alkoxide crosslinking agent, metal chelate crosslinking agent, metal salt crosslinking agent, ammonium salt crosslinking agent Agents and the like. Among the above, when the reactive group of the (meth) acrylic acid ester copolymer (A) is a hydroxyl group, it is preferable to use an isocyanate-based crosslinking agent excellent in reactivity with the hydroxyl group, and (meth) acrylic acid When the reactive group which the ester copolymer (A) has is a carboxy group, it is preferable to use an epoxy-based crosslinking agent excellent in reactivity with the carboxy group. In addition, a thermal crosslinking agent (B) can be used individually by 1 type or in combination of 2 or more types.

  The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and the like. , And their biuret bodies, isocyanurate bodies, and adduct bodies that are a reaction product with low molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanate, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are preferable from the viewpoint of reactivity with hydroxyl groups.

  Examples of the epoxy-based crosslinking agent include 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl ether. 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, diglycidylamine and the like. Of these, 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane is preferred from the viewpoint of reactivity with a carboxy group.

  The content of the thermal crosslinking agent (B) in the adhesive composition P is preferably 0.01 parts by mass or more with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A), and in particular. The amount is preferably 0.05 parts by mass or more, and more preferably 0.1 parts by mass or more. Further, the content is preferably 10 parts by mass or less, particularly preferably 5 parts by mass or less, and further preferably 0.4 parts by mass or less. When the content of the thermal crosslinking agent (B) is in the above range, the pressure-sensitive adhesive layer 11 having a relatively high coating strength and exhibiting a good cohesive force while the resulting pressure-sensitive adhesive has sufficient flexibility. can get.

(3) UV curable component (C)
When the adhesive composition P contains the ultraviolet curable component (C), the formed adhesive layer 11 becomes an ultraviolet curable adhesive layer. In the pressure-sensitive adhesive layer 11, the ultraviolet curable components (C) are polymerized to each other by curing by ultraviolet irradiation after the adherend is pasted, and the polymerized ultraviolet curable components (C) are co-polymerized with (meth) acrylate ester. It is presumed to be entangled with the crosslinked structure (three-dimensional network structure) of the union (A). The pressure-sensitive adhesive having such a higher-order structure is excellent in step followability and blister resistance under high temperature and high humidity conditions.

  The ultraviolet curable component (C) is not particularly limited as long as it is a component that can be cured by irradiation with ultraviolet rays in the presence of the photopolymerization initiator (D) described later, and obtain the above-described effects. Any of them or a mixture thereof may be used. Among them, a polyfunctional acrylate monomer having a molecular weight of less than 1,000, which is excellent in compatibility with the (meth) acrylic acid ester copolymer (A) and the like can be preferably exemplified.

  Examples of polyfunctional acrylate monomers having a molecular weight of less than 1000 include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and polyethylene glycol diene. (Meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified Di (meth) acrylate phosphate, di (acryloxyethyl) isocyanurate, allylated cyclohexyl di (meth) acrylate, ethoxylated bisphenol A diacrylate, 9,9-bi Bifunctional type such as [4- (2-acryloyloxyethoxy) phenyl] fluorene; trimethylolpropane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid-modified dipentaerythritol tri (meth) acrylate, penta Trifunctional such as erythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, ε-caprolactone modified tris- (2- (meth) acryloxyethyl) isocyanurate Type; tetrafunctional type such as diglycerin tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate; pentafunctional type such as propionic acid-modified dipentaerythritol penta (meth) acrylate And hexafunctional types such as dipentaerythritol hexa (meth) acrylate and caprolactone-modified dipentaerythritol hexa (meth) acrylate. Among these, di (acryloxyethyl) isocyanurate, tris (acryloxyethyl) isocyanurate, and ε-caprolactone-modified tris from the viewpoint of step following ability and blister resistance under high temperature and high humidity conditions of the obtained adhesive. -A polyfunctional acrylate monomer containing an isocyanurate structure in the molecule, such as-(2- (meth) acryloxyethyl) isocyanurate, is preferred, and a polyfunctional acrylate having a trifunctional or higher functionality and an isocyanurate structure in the molecule Type monomers are more preferable, and ε-caprolactone-modified tris- (2- (meth) acryloxyethyl) isocyanurate is particularly preferable. These may be used individually by 1 type and may be used in combination of 2 or more type.

  As the ultraviolet curable component (C), an ultraviolet curable acrylate oligomer can also be used. The acrylate oligomer preferably has a weight average molecular weight of 50,000 or less. Examples of such acrylate oligomers include polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polybutadiene acrylate, and silicone acrylate.

  The weight average molecular weight of the acrylate oligomer is preferably 50,000 or less, particularly preferably 500 to 50,000, and more preferably 3,000 to 40,000. These acrylate oligomers may be used alone or in combination of two or more.

  Further, as the ultraviolet curable component (C), an adduct acrylate polymer in which a group having a (meth) acryloyl group is introduced into a side chain can also be used. Such an adduct acrylate-based polymer uses a copolymer of (meth) acrylic acid ester and a monomer having a crosslinkable functional group in the molecule, and a part of the crosslinkable functional group of the copolymer. , A (meth) acryloyl group and a compound having a group that reacts with a crosslinkable functional group can be reacted.

  The weight average molecular weight of the adduct acrylate polymer is preferably about 50,000 to 900,000, and particularly preferably about 100,000 to 500,000.

  The ultraviolet curable component (C) can be used by selecting one from among the above-mentioned polyfunctional acrylate monomers, acrylate oligomers and adduct acrylate polymers, or can be used in combination of two or more. And it can also be used in combination with other ultraviolet curable components.

  The content of the ultraviolet curable component (C) in the pressure-sensitive adhesive composition P is (meth) from the viewpoint of excellent step followability and blister resistance under high-temperature and high-humidity conditions of the resulting pressure-sensitive adhesive. The amount is preferably 1 part by mass or more, more preferably 2 parts by mass or more, and particularly preferably 3 parts by mass or more with respect to 100 parts by mass of the acrylic ester copolymer (A). On the other hand, the content is preferably 30 parts by mass or less, and preferably 15 parts by mass or less, from the viewpoint of preventing cross-links from becoming too dense and lowering the adhesive strength to deteriorate durability. More preferred is 10 parts by mass or less.

(4) Photopolymerization initiator (D)
The photopolymerization initiator (D) in this embodiment has an absorbance at a wavelength of 380 nm in an acetonitrile solution having a concentration of 0.1% by mass of 0.3 or more. When the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 contains the photopolymerization initiator (D), even when the pressure-sensitive adhesive layer 11 is irradiated with ultraviolet rays through the display member constituting member containing the ultraviolet absorber, The pressure-sensitive adhesive layer 11 (ultraviolet curable component (C)) is cured satisfactorily and has excellent step followability and blister resistance under high temperature and high humidity conditions.

  From the above viewpoint, the absorbance at a wavelength of 380 nm of the photopolymerization initiator (D) is preferably 0.5 or more, and particularly preferably 1.0 or more. The upper limit of the absorbance is not particularly limited, but is usually preferably 2.5 or less, and particularly preferably 2.0 or less. When the absorbance exceeds 2.5, the curing reaction of the UV curable component (C) by the photopolymerization initiator (D) proceeds by the ambient light of the fluorescent lamp or the like during the formation of the adhesive sheet or storage, and the subsequent use There is a case where the step following ability at the time is lowered. Here, the measuring method of the light absorbency of a photoinitiator (D) is as showing to the test example mentioned later.

  The photopolymerization initiator (D) preferably has an absorption maximum wavelength of absorbance of 200 to 500 nm in an acetonitrile solution having a concentration of 0.1% by mass of 350 nm or more, particularly preferably 370 nm or more. Is preferably at least 380 nm. When there are a plurality of absorption maximum wavelengths having an absorbance of 200 to 500 nm, at least one absorption maximum wavelength may be in the above range. Thereby, when the adhesive layer 11 is irradiated with ultraviolet rays through the display member-constituting member containing the ultraviolet absorber, the curability of the adhesive layer 11 (ultraviolet curable component (C)) is further improved and the high temperature is increased. The step following property and the blister resistance under the high humidity condition are more excellent. On the other hand, the upper limit value of the absorption maximum wavelength is not particularly limited, but is preferably 450 nm or less, particularly 410 nm or less, from the viewpoint of preventing the progress of the curing reaction when the pressure-sensitive adhesive layer 11 is stored in ambient light. It is preferable that the thickness is 405 nm or less.

  Examples of such photopolymerization initiator (D) include 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, and the like. . These may be used alone or in combination of two or more.

  Moreover, in the adhesive (adhesive composition P) in this embodiment, the absorbance at a wavelength of 380 nm in an acetonitrile solution having a concentration of 0.1% by mass with the photopolymerization initiator (D) is less than 0.3. A photopolymerization initiator (hereinafter sometimes referred to as “photopolymerization initiator (ND)”) may be used in combination. Examples of the photopolymerization initiator (ND) include 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethane- 1-one etc. are mentioned. In this case, the ratio of the photopolymerization initiator (ND) to 100 parts by mass of the photopolymerization initiator (D) is preferably 50 to 150 parts by mass, particularly preferably 75 to 125 parts by mass, It is preferable that it is 80-120 mass parts.

  The photopolymerization initiator (D) is preferably used in an amount in the range of 2 to 15 parts by mass, particularly 4 to 12 parts by mass with respect to 100 parts by mass of the ultraviolet curable component (C).

(5) Silane coupling agent (E)
The adhesive composition P preferably further contains a silane coupling agent (E). Thereby, when a to-be-adhered body has a glass member, the adhesive obtained will improve adhesiveness with the glass member. Further, even when the adherend is a plastic plate, the adhesive obtained has improved adhesion to the plastic plate. As a result, the obtained pressure-sensitive adhesive is excellent in the step following ability under high temperature and high humidity conditions.

  The silane coupling agent (E) is an organosilicon compound having at least one alkoxysilyl group in the molecule, has good compatibility with the (meth) acrylic acid ester copolymer (A), and is light transmissive. Those having the following are preferred.

  Examples of the silane coupling agent (E) include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, Mercapto groups such as silicon compounds having an epoxy structure such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyldimethoxymethylsilane Contains amino groups such as silicon compounds, 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane Silicon compound, 3-chloropropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, or at least one of them, and alkyl groups such as methyltriethoxysilane, ethyltriethoxysilane, methyltrimethoxysilane, ethyltrimethoxysilane Examples include condensates with silicon compounds. These may be used individually by 1 type and may be used in combination of 2 or more type.

  The content of the silane coupling agent (E) in the adhesive composition P is preferably 0.01 parts by mass or more with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A). In particular, it is preferably 0.05 parts by mass or more, and more preferably 0.1 parts by mass or more. In addition, the content is preferably 1 part by mass or less, particularly preferably 0.5 part by mass or less, and further preferably 0.3 part by mass or less.

(6) Various additives For the adhesive composition P, various additives usually used for acrylic pressure-sensitive adhesives, for example, ultraviolet absorbers, antistatic agents, tackifiers, antioxidants, and light stabilizers are optionally used. An agent, a softening agent, a filler, a refractive index adjusting agent and the like can be added. In addition, the below-mentioned polymerization solvent and dilution solvent shall not be contained in the additive which comprises the adhesive composition P.

(7) Manufacture of adhesive composition The adhesive composition P manufactured the (meth) acrylic acid ester copolymer (A), the obtained (meth) acrylic acid ester copolymer (A), and heat A cross-linking agent (B), an ultraviolet curable component (C), and a photopolymerization initiator (D) are mixed, and optionally produced by adding a silane coupling agent (E) and / or an additive. be able to.

  The (meth) acrylic acid ester copolymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by an ordinary radical polymerization method. The polymerization of the (meth) acrylic acid ester copolymer (A) can be carried out by a solution polymerization method or the like using a polymerization initiator as desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like. Two or more kinds may be used in combination.

  Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more kinds may be used in combination. Examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane 1-carbonitrile), 2 , 2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2′-azobis (2-methylpropionate) 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-hydroxymethylpropionitrile), 2,2′-azobis [2- (2-imidazolin-2-yl) Propane] and the like.

  Examples of organic peroxides include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and di (2-ethoxyethyl) peroxy. Examples include dicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

  In addition, in the said superposition | polymerization process, the weight average molecular weight of the polymer obtained can be adjusted by mix | blending chain transfer agents, such as 2-mercaptoethanol.

  Once the (meth) acrylic acid ester copolymer (A) is obtained, the solution of the (meth) acrylic acid ester copolymer (A) is added to the thermal crosslinking agent (B), the ultraviolet curable component (C), and photopolymerization. An adhesive composition P is obtained by adding an initiator (D), and optionally a silane coupling agent (E) and additives, and mixing them well.

(8) Formation of pressure-sensitive adhesive layer The pressure-sensitive adhesive layer 11 is formed by thermally crosslinking the pressure-sensitive adhesive composition P. That is, the adhesive composition P is crosslinked by heat treatment. In addition, this heat processing can also serve as the drying process after application | coating of the adhesive composition P. FIG.

  The heating temperature of the heat treatment is preferably 50 to 150 ° C, and particularly preferably 70 to 120 ° C. The heating time is preferably 10 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes. Furthermore, it is particularly preferable to provide a curing period of about 1 to 2 weeks at room temperature (for example, 23 ° C., 50% RH) after the heat treatment.

  By the heat treatment (and curing), the (meth) acrylic acid ester copolymer (A) is well crosslinked through the thermal crosslinking agent (B).

  The thickness (value measured according to JIS K7130) of the pressure-sensitive adhesive layer 11 is preferably 20 μm or more as a lower limit, more preferably 25 μm or more, particularly preferably 30 μm or more, It is preferable that it is 50 micrometers or more. When the lower limit value of the thickness of the pressure-sensitive adhesive layer 11 is 20 μm or more, desired adhesive force is easily exhibited. Moreover, sufficient level | step difference followable | trackability can be ensured with respect to the normal level | step difference of a display body structural member as the lower limit of the thickness of the adhesive layer 11 is 30 micrometers or more.

  The thickness of the pressure-sensitive adhesive layer 11 is preferably 500 μm or less as an upper limit, more preferably 400 μm or less, and particularly preferably 300 μm or less. When the upper limit value of the thickness of the pressure-sensitive adhesive layer 11 is not more than the above, workability is good. The pressure-sensitive adhesive layer 11 may be formed as a single layer or may be formed by laminating a plurality of layers.

(9) Gel fraction (before UV irradiation)
The gel fraction of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 (before ultraviolet irradiation) is preferably 30% or more as a lower limit, more preferably 40% or more, and particularly preferably 50% or more. preferable. When the lower limit of the gel fraction of the pressure-sensitive adhesive before ultraviolet irradiation is the above or higher, the cohesive force of the pressure-sensitive adhesive layer 11 is improved, and the coating strength is higher. Further, the gel fraction of the pressure-sensitive adhesive before ultraviolet irradiation is preferably 70% or less as an upper limit, particularly preferably 65% or less, and further preferably 60% or less. When the upper limit of the gel fraction of the pressure-sensitive adhesive before ultraviolet irradiation is not more than the above, the pressure-sensitive adhesive does not become too hard, and the initial step followability becomes more excellent. The method for measuring the gel fraction of this pressure-sensitive adhesive (before ultraviolet irradiation) is as shown in the test examples described later.

2. Release sheet As the release sheets 12a and 12b, for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, Polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene / (meth) acrylic acid copolymer film, ethylene / (meth) acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film A fluororesin film or the like is used. These crosslinked films are also used. Furthermore, these laminated films may be sufficient.

  It is preferable that the peeling surface (especially the surface in contact with the pressure-sensitive adhesive layer 11) of the release sheets 12a and 12b is subjected to a peeling treatment. Examples of the release agent used for the release treatment include alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax release agents. Of the release sheets 12a and 12b, one release sheet is preferably a heavy release release sheet having a high release force, and the other release sheet is preferably a light release release sheet having a low release force.

  Although there is no restriction | limiting in particular about the thickness of release sheet 12a, 12b, Usually, it is about 20-150 micrometers.

3. Manufacture of an adhesive sheet As one manufacture example of the adhesive sheet 1, the coating liquid of the said adhesive composition P is apply | coated to the peeling surface of one peeling sheet 12a (or 12b), it heat-processes, and an adhesive composition is performed. After P is thermally crosslinked to form a coating layer, the release surface of the other release sheet 12b (or 12a) is superimposed on the coating layer. When a curing period is required, a curing period is set, and when the curing period is unnecessary, the coating layer becomes the pressure-sensitive adhesive layer 11 as it is. Thereby, the said adhesive sheet 1 is obtained. The conditions for the heat treatment and curing are as described above.

  As another production example of the pressure-sensitive adhesive sheet 1, a coating liquid of the above-mentioned pressure-sensitive adhesive composition P is applied to the release surface of one release sheet 12a, heat-treated to thermally cross-link the pressure-sensitive adhesive composition P, and then applied. A layer is formed to obtain a release sheet 12a with a coating layer. Moreover, the coating liquid of the said adhesive composition P is apply | coated to the peeling surface of the other peeling sheet 12b, heat processing is performed, the adhesive composition P is heat-crosslinked, a coating layer is formed, and a coating layer is attached. The release sheet 12b is obtained. And the peeling sheet 12a with an application layer and the peeling sheet 12b with an application layer are bonded together so that both application layers may mutually contact. When the curing period is necessary, the curing period is set, and when the curing period is unnecessary, the above-mentioned laminated application layer becomes the pressure-sensitive adhesive layer 11 as it is. Thereby, the said adhesive sheet 1 is obtained. According to this production example, even when the pressure-sensitive adhesive layer 11 is thick, it can be stably produced.

  For example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used as a method for applying the coating solution of the adhesive composition P.

  Since the pressure-sensitive adhesive sheet 1 according to this embodiment has a relatively high coating strength of the pressure-sensitive adhesive layer 11, when the pressure-sensitive adhesive sheet 1 is cut or the like, the pressure-sensitive adhesive protrudes from the cut surface, and the pressure-sensitive adhesive adheres to the blade. Occurrence of problems such as the occurrence of such a problem is suppressed. In addition, the adhesive is prevented from oozing out from the adhesive layer 11 when the adhesive sheet 1 is stored.

[Display]
As shown in FIG. 2, the display body 2 according to this embodiment includes a first display body constituent member 21 (one display body constituent member) having a step on at least a surface to be bonded, and a second display body. The display body constituent member 22 (other display body constituent member) and the post-curing pressure-sensitive adhesive layer 11 which is located between them and bonds the first display body constituent member 21 and the second display body constituent member 22 to each other. 'And configured with. In the display body 2 according to the present embodiment, the first display body constituting member 21 has a step on the surface of the post-curing pressure-sensitive adhesive layer 11 ′ side, specifically, a step due to the printed layer 3. doing.

  The post-curing pressure-sensitive adhesive layer 11 ′ in the display body 2 is obtained by curing the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 by ultraviolet irradiation. This post-curing pressure-sensitive adhesive layer 11 ′ has a crosslinked structure composed of a (meth) acrylic acid ester copolymer (A) and a thermal crosslinking agent (B), and an ultraviolet curable component (C ) Cured product (polymer) and a pressure-sensitive adhesive containing a photopolymerization initiator (D). The polymerized ultraviolet curable component (C) is presumed to be entangled with a crosslinked structure composed of the (meth) acrylic acid ester copolymer (A) and the thermal crosslinking agent (B).

  The photopolymerization initiator (D) contained in the pressure-sensitive adhesive constituting the post-curing pressure-sensitive adhesive layer 11 ′ is also cleaved by ultraviolet irradiation when the photopolymerization initiator (D) contained in the pressure-sensitive adhesive composition P is used. It is what remains. Therefore, the content thereof is not large, and is usually 0.0001% by mass or more and 0.1% by mass or less, preferably 0.0001% by mass or more and 0.01% by mass or less in the pressure-sensitive adhesive. .

  Secondly, the post-curing pressure-sensitive adhesive layer 11 ′ has a crosslinked structure composed of a (meth) acrylic acid ester copolymer (A) and a thermal crosslinking agent (B), and an ultraviolet curable component (C It is preferable that the gel fraction of the pressure-sensitive adhesive (after ultraviolet irradiation) is 40% or more and 95% or less. The gel fraction of the pressure-sensitive adhesive constituting the post-curing pressure-sensitive adhesive layer 11 ′ is based on the gel fraction of the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11 before UV-curing by UV-curing the UV-curable component (C). Also gets higher.

  When the adhesive layer 11 is irradiated with ultraviolet rays through a display member that does not contain an ultraviolet absorber, the gel fraction of the adhesive constituting the cured adhesive layer 11 ′ is 65% or more as the lower limit. Is more preferable, and 70% or more is particularly preferable. In addition, when the adhesive layer 11 is irradiated with ultraviolet rays through a display member that contains an ultraviolet absorber, the gel fraction of the adhesive constituting the cured adhesive layer 11 ′ is 40% or more as the lower limit. Preferably, it is 60% or more, more preferably 62% or more. When the lower limit of the gel fraction of the pressure-sensitive adhesive after UV irradiation is the above or more, the step following property and blister resistance under high-temperature and high-humidity conditions in the post-curing pressure-sensitive adhesive layer 11 ′ of the display body 2 are more excellent. It will be a thing.

  On the other hand, when the adhesive layer 11 is irradiated with ultraviolet rays through a display member that does not contain an ultraviolet absorber, the gel fraction of the adhesive constituting the cured adhesive layer 11 ′ is 90% or less as an upper limit. In particular, it is preferably 85% or less, and more preferably 80% or less. Further, when the adhesive layer 11 is irradiated with ultraviolet rays through a display member constituting member containing an ultraviolet absorber, the gel fraction of the adhesive constituting the cured adhesive layer 11 ′ is 90% or less as an upper limit. In particular, it is preferably 80% or less, and more preferably 75% or less. When the upper limit value of the gel fraction of the pressure-sensitive adhesive after ultraviolet irradiation is not more than the above, it is possible to prevent the adhesive force of the post-curing pressure-sensitive adhesive layer 11 ′ from being lowered and the durability from being deteriorated. The method for measuring the gel fraction of this pressure-sensitive adhesive (after ultraviolet irradiation) is as shown in the test examples described later.

The post-curing pressure-sensitive adhesive layer 11 ′ has a step follow-up rate (%) represented by the following formula of 20% or more as a lower limit, particularly preferably 25% or more, and more preferably 30% or more. It is preferable that Further, the upper limit value of the step following rate is not particularly limited, but is usually preferably 80% or less, and particularly preferably 70% or less.
Step follow-up rate (%) = {(the height of the step (μm) in which the buried state is maintained without bubbles, floats, peeling, etc. after a predetermined durability test) / (thickness of the adhesive layer)} × 100
In addition, the test method of a level | step difference tracking rate is as showing to the test example mentioned later.

  Since the step following rate of the post-curing pressure-sensitive adhesive layer 11 ′ is in the above range, the post-curing pressure-sensitive adhesive layer 11 ′ is a display body constituent member (first display body constituent member 21) even after a durability test. The step is satisfactorily followed, and the occurrence of bubbles, floating, peeling, etc. in the vicinity of the step is suppressed, thereby suppressing the occurrence of light reflection loss.

  Examples of the display body 2 include a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, electronic paper, and the like, and may be a touch panel. Moreover, as the display body 2, the member which comprises those some may be sufficient.

  It is preferable that the 1st display body structural member 21 is a protection panel which consists of a laminated body etc. other than a glass plate, a plastic plate, etc. In this case, the print layer 3 is generally formed in a frame shape on the post-curing pressure-sensitive adhesive layer 11 ′ side of the first display member constituting member 21.

  It is preferable that the 1st display body structural member 21, especially the 1st display body structural member 21 as a protection panel contain the ultraviolet absorber. In this case, the display body 2 is excellent in light resistance, and even if the display body 2 after manufacture is exposed to ultraviolet rays from the first display body constituting member 21 side, the post-curing pressure-sensitive adhesive layer 11 ′ and Deterioration of the second display member constituting member 22 in the lower layer is suppressed. In particular, in the post-curing pressure-sensitive adhesive layer 11 ′, excellent step followability and blister resistance are maintained well.

  The glass plate is not particularly limited. For example, chemically tempered glass, alkali-free glass, quartz glass, soda lime glass, barium / strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate Glass etc. are mentioned. Although the thickness of a glass plate is not specifically limited, Usually, it is 0.1-5 mm, Preferably it is 0.2-2 mm.

  The plastic plate is not particularly limited, and examples thereof include an acrylic plate and a polycarbonate plate. Although the thickness of a plastic board is not specifically limited, Usually, it is 0.2-5 mm, Preferably it is 0.4-3 mm.

  Various functional layers (transparent conductive film, metal layer, silica layer, hard coat layer, antiglare layer, etc.) may be provided on one or both surfaces of the glass plate or plastic plate, or an optical member. May be laminated. Moreover, the transparent conductive film and the metal layer may be patterned.

  The second display member constituting member 22 includes an optical member to be attached to the first display member constituting member 21, a display member module (for example, a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic) EL) module, etc.), an optical member as a part of the display module, or a laminate including the display module. Note that the display module normally does not transmit ultraviolet rays.

  Examples of the optical member include a scattering prevention film, a polarizing plate (polarizing film), a polarizer, a retardation plate (retarding film), a viewing angle compensation film, a brightness enhancement film, a contrast enhancement film, a liquid crystal polymer film, and a diffusion film. , Transflective film, transparent conductive film, and the like. Examples of the scattering prevention film include a hard coat film in which a hard coat layer is formed on one side of a base film. The optical member may contain an ultraviolet absorber.

  The material which comprises the printing layer 3 is not specifically limited, The well-known material for printing is used. The lower limit of the thickness of the printing layer 3, that is, the height of the step, is preferably 3 μm or more, more preferably 5 μm or more, particularly preferably 7 μm or more, and most preferably 10 μm or more. preferable. When the lower limit value is equal to or greater than the above, it is possible to sufficiently ensure concealability such as making the electrical wiring invisible from the viewer side. The upper limit value is preferably 50 μm or less, more preferably 35 μm or less, particularly preferably 25 μm or less, and further preferably 20 μm or less. When the upper limit value is equal to or less than the above, it is possible to prevent the step following property of the post-curing pressure-sensitive adhesive layer 11 ′ from deteriorating with respect to the print layer 3.

  The most preferable embodiment of the display body 2 is a protective panel in which the first display body constituting member 21 includes a plastic plate containing an ultraviolet absorber, and the second display body constituting member 22 is a display body module that does not transmit ultraviolet rays. It is a touch panel. In addition, the patterned transparent conductive film and metal layer may exist in any site. Such a display body 2 is excellent in all of light resistance, level difference followability, and blister resistance.

  In order to manufacture the said display body 2, as an example, one peeling sheet 12a of the adhesive sheet 1 is peeled, and the adhesive layer 11 which the adhesive sheet 1 exposed is used as the printing layer of the 1st display body structural member 21. It is bonded to the surface on the side where 3 is present. At this time, since the pressure-sensitive adhesive layer 11 is excellent in the initial step followability, it is possible to suppress the occurrence of gaps and floats in the vicinity of the step due to the printing layer 3.

  Next, the other release sheet 12b is peeled from the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1, and the pressure-sensitive adhesive layer 11 exposed from the pressure-sensitive adhesive sheet 1 and the second display member constituting member 22 are bonded together to obtain a laminate. . As another example, the bonding order of the first display member constituting member 21 and the second display member constituting member 22 may be switched.

  Thereafter, the pressure-sensitive adhesive layer 11 in the laminate is irradiated with ultraviolet rays. Thereby, the ultraviolet curable component (C) in the pressure-sensitive adhesive layer 11 is polymerized, and the pressure-sensitive adhesive layer 11 is cured to become a pressure-sensitive adhesive layer 11 ′ after curing. Irradiation of the ultraviolet ray to the pressure-sensitive adhesive layer 11 is usually performed through one of the first display member constituting member 21 and the second display member constituting member 22, and preferably the first display member structure as a protective panel. Perform over member 21. Here, even when the display member constituting member on the ultraviolet irradiation side (preferably, the first display member constituting member 21 as a protective panel) contains an ultraviolet absorber, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 11. Since the photopolymerization initiator (D) contained in has an absorbance at a wavelength of 380 nm of 0.3 or more, ultraviolet light having a wavelength for cleaving the photopolymerization initiator (D) is contained in the display member constituting member. The photopolymerization initiator (D) is cleaved without any problem without being absorbed by the UV absorber. As a result, the curing reaction of the ultraviolet curable component (C) proceeds well, and the pressure-sensitive adhesive layer 11 is sufficiently cured. Thereby, the obtained display body 2 becomes excellent in the level | step difference followability and blister resistance under high temperature, high humidity conditions.

Irradiation with ultraviolet rays can be performed by a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, or the like, and the irradiation amount of ultraviolet rays is preferably about 50 to 1000 mW / cm ^{2 in} illuminance. Further, the light quantity is preferably 50~10000mJ / cm ^2, more preferably 80~5000mJ / cm ^2, and particularly preferably 200~2000mJ / cm ^2.

  In the above display body 2, since the post-curing pressure-sensitive adhesive layer 11 ′ is excellent in step followability even under high temperature and high humidity conditions, the display body 2 is subjected to high temperature and high humidity conditions (for example, 85 ° C., 85% RH, 72 hours). ), It is possible to suppress the occurrence of bubbles, floating, peeling, etc. in the vicinity of the step.

  Moreover, in the said display body 2, since adhesive layer 11 'after hardening is excellent in blister resistance, the display body 2 is put on high temperature, high humidity conditions (for example, 85 degreeC, 85% RH, 72 hours), Even when outgas is generated from a display member made of a plastic plate or the like, it is possible to suppress generation of blisters such as bubbles, floats, and peeling at the interface between the cured pressure-sensitive adhesive layer 11 ′ and the display member members 21 and 22. Is done.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, one of the release sheets 12a and 12b in the pressure-sensitive adhesive sheet 1 may be omitted. Further, the first display member constituting member 21 may have a step other than the printing layer 3 or may not have a step. Further, not only the first display member constituting member 21 but also the second display member constituting member 22 may have a step on the cured adhesive layer 11 ′ side.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Example 1]
1. Preparation of (meth) acrylic acid ester copolymer 60 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of isobornyl acrylate, 10 parts by mass of N-acryloylmorpholine, and 20 parts by mass of 2-hydroxyethyl acrylate were copolymerized. (Meth) acrylic acid ester copolymer (A) was prepared. When the molecular weight of this (meth) acrylic acid ester copolymer (A) was measured by the method mentioned later, it was weight average molecular weight (Mw) 500,000.

2. Preparation of Adhesive Composition 100 parts by weight (solid content converted value; the same applies hereinafter) of the (meth) acrylic acid ester copolymer (A) obtained in Step 1 above, and trimethylolpropane as a thermal crosslinking agent (B) 0.2 parts by mass of modified tolylene diisocyanate, 5.0 parts by mass of ε-caprolactone-modified tris- (2-acryloxyethyl) isocyanurate as an ultraviolet curable component (C), and as a photopolymerization initiator (D) Of 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide and 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name “ KBM-403 ") is mixed with 0.3 part by mass, sufficiently stirred, and diluted with methyl ethyl ketone to give a solid content concentration of 50% by mass. To obtain a coating solution of Narubutsu.

3. Production of pressure-sensitive adhesive sheet Peeling of a heavy-peelable release sheet (product name "SP-PET752150", manufactured by Lintec Corporation), in which one side of a polyethylene terephthalate film was subjected to a release treatment with a silicone-based release agent The treated surface was applied with a knife coater. And the application layer was heat-processed at 90 degreeC for 1 minute (s), and the application layer was formed.

  Next, a light release type release sheet (product name “SP-PET382120”, manufactured by Lintec Corporation) in which the coating layer on the heavy release type release sheet obtained above and one side of the polyethylene terephthalate film were release-treated with a silicone-based release agent Are bonded so that the release-treated surface of the light release-type release sheet is in contact with the coating layer, and is cured for 7 days under conditions of 23 ° C. and 50% RH, thereby forming a 50 μm thick adhesive layer. A pressure-sensitive adhesive sheet having a constitution of heavy release type release sheet / pressure-sensitive adhesive layer (thickness: 50 μm) / light release type release sheet was prepared. The thickness of the pressure-sensitive adhesive layer is a value measured using a constant pressure thickness measuring instrument (manufactured by Teclock, product name “PG-02”) in accordance with JIS K7130.

Here, Table 1 shows each composition (solid content converted value) of the adhesive composition when the (meth) acrylic acid ester copolymer (A) is 100 parts by mass (solid content converted value). Details of the abbreviations and the like described in Table 1 are as follows.
[(Meth) acrylic ester copolymer (A)]
2EHA: 2-ethylhexyl acrylate IBXA: isobornyl acrylate ACMO: N-acryloylmorpholine HEA: 2-hydroxyethyl acrylate BA: n-butyl acrylate AA: acrylic acid
[Thermal crosslinking agent (B)]
TDI system: trimethylolpropane modified tolylene diisocyanate Epoxy system: 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane
[Photopolymerization initiator (D)]
D1: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide D2: bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide D3: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide And 4-hydroxy-2-methyl-1-phenylpropan-1-one mixed at a mass ratio of 1: 1 D4: 1-hydroxycyclohexyl phenyl ketone

[Examples 2-5, Comparative Examples 1-2]
The type and ratio of each monomer constituting the (meth) acrylic acid ester copolymer (A), the type and blending amount of the thermal crosslinking agent (B), the blending amount of the ultraviolet curable component (C), and the photopolymerization initiator. A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the type and blending amount of (D) were changed as shown in Table 1.

Here, the above-mentioned weight average molecular weight (Mw) is a weight average molecular weight in terms of standard polystyrene measured (GPC measurement) using gel permeation chromatography (GPC) under the following conditions.
<Measurement conditions>
GPC measurement device: manufactured by Tosoh Corporation, HLC-8020
GPC column (passed in the following order): TSK guard column HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (× 2)
TSK gel G2000HXL
・ Measurement solvent: Tetrahydrofuran ・ Measurement temperature: 40 ° C.

[Test Example 1] (Measurement of absorbance)
An acetonitrile solution having a concentration of 0.1% by mass of the photopolymerization initiator used in Examples and Comparative Examples was prepared, and the absorbance in the wavelength range of 200 to 500 nm in the solution was measured by Shimadzu Corporation, product name “UV- 3600 "). Based on the result, an absorbance at a wavelength of 380 nm and an absorption maximum wavelength (nm) at an absorbance at a wavelength of 200 to 500 nm were derived. The results are shown in Table 1.

[Test Example 2] (Measurement of gel fraction)
The pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were cut into a size of 80 mm × 80 mm, the pressure-sensitive adhesive layer was wrapped in a polyester mesh (mesh size 200), the mass was weighed with a precision balance, and the mesh By subtracting the single mass, the mass of the adhesive alone was calculated. The mass at this time is M1.

  Next, the pressure-sensitive adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23 ° C.) for 72 hours. Thereafter, the pressure-sensitive adhesive was taken out, air-dried for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and further dried in an oven at 80 ° C. for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the pressure sensitive adhesive alone was calculated by subtracting the mass of the mesh alone. The mass at this time is M2. The gel fraction (%) is represented by (M2 / M1) × 100. This derived | led-out the gel fraction (before ultraviolet irradiation) of an adhesive. The results are shown in Table 2.

  On the other hand, the light release type release sheet was peeled from the pressure sensitive adhesive sheets obtained in Examples and Comparative Examples, and the exposed pressure sensitive adhesive layer was directly irradiated with ultraviolet rays under the following conditions to cure and cure the pressure sensitive adhesive layer. It was set as the back adhesive layer. About the adhesive of this adhesive layer after hardening, the gel fraction (after ultraviolet irradiation; direct irradiation) was derived | led-out similarly to the above. The results are shown in Table 2.

  In addition, the light release type release sheet was peeled from the pressure sensitive adhesive sheets obtained in Examples and Comparative Examples, and the exposed pressure sensitive adhesive layer was replaced with a resin plate having a polymethyl methacrylate layer and a polycarbonate layer (manufactured by Mitsubishi Gas Chemical Company, product It was bonded to the surface of the polycarbonate layer side of the name “Iupilon sheet MR-58U” (thickness: 0.8 mm, containing UV absorber). Next, the pressure-sensitive adhesive layer was irradiated with ultraviolet rays under the following conditions through the resin plate to cure the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive layer after curing. About the adhesive of this adhesive layer after hardening, the gel fraction (after ultraviolet irradiation; irradiation through a resin board) was derived | led-out similarly to the above. Moreover, the value which deducted the gel fraction after the ultraviolet irradiation which concerns on the resin board irradiation from the gel fraction after the ultraviolet irradiation which concerns on direct irradiation was computed. The results are shown in Table 2.

<Ultraviolet irradiation conditions>
・ Use of high-pressure mercury lamp ・ Illuminance 200mW / cm ² , Light quantity 2000mJ / cm ²
・ Uses UVGraph-A1 made by Eye Graphics as UV illuminance / light meter

[Test Example 3] (Evaluation of blister resistance)
Polyethylene terephthalate film (manufactured by Oike Kogyo Co., Ltd., ITO film, thickness) provided with a transparent conductive film made of tin-doped indium oxide (ITO) on one side of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet obtained in Examples and Comparative Examples 125 μm) transparent conductive film, and a resin plate having a polymethyl methacrylate layer and a polycarbonate layer (Mitsubishi Gas Chemical Co., Ltd., product name “Iupilon sheet MR-58U”, thickness: 0.8 mm, containing UV absorber) Sandwiched between the polycarbonate layer side surfaces. Then, it was autoclaved for 30 minutes under the conditions of 50 ° C. and 0.5 MPa, and left at normal pressure, 23 ° C. and 50% RH for 24 hours.

The pressure-sensitive adhesive layer of the obtained laminate was irradiated with ultraviolet rays through the resin plate under the same conditions as in Test Example 2 to cure the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive layer after curing. Subsequently, it was stored for 72 hours under high temperature and high humidity conditions of 85 ° C. and 85% RH. Thereafter, the state at the interface between the adhesive layer after curing and the adherend was visually confirmed, and blister resistance was evaluated according to the following criteria. The results are shown in Table 2.
○… No bubbles or floating / peeling ××: Bubbles, bubble marks or floating / peeling

[Test Example 4] (Measurement of step following rate 1)
On the surface of a glass plate (manufactured by NSG Precision, product name “Corning Glass Eagle XG”, length 90 mm × width 50 mm × thickness 0.5 mm), UV curable ink (product name “POS-911 Black”, manufactured by Teikoku Ink Co., Ltd.) ) Was screen-printed in a frame shape (outer shape: 90 mm long × 50 mm wide, 5 mm wide) so that the coating thickness was any one of 25 μm, 30 μm and 40 μm. Next, irradiation with ultraviolet rays (80 W / cm ² , ^two metal halide lamps, lamp height of 15 cm, belt speed of 10 to 15 m / min) is performed to cure the printed ultraviolet curable ink, and a level difference due to printing (level difference) A stepped glass plate having a thickness of any one of 25 μm, 30 μm, and 40 μm was produced.

  The light release type release sheet was peeled off from the pressure sensitive adhesive sheets obtained in Examples and Comparative Examples, and the exposed pressure sensitive adhesive layer was replaced with a polyethylene terephthalate film having an easy adhesion layer (product name “PET A4300” manufactured by Toyobo Co., Ltd., thickness: 100 μm) easy adhesion layer. Next, the heavy release type release sheet is peeled off to expose the pressure-sensitive adhesive layer, and each step is provided so that the pressure-sensitive adhesive layer covers the entire frame-like printed surface using a laminator (product name “LPD3214” manufactured by Fuji Plastics). Laminated on a glass plate. Then, it was autoclaved for 30 minutes under the conditions of 50 ° C. and 0.5 MPa, and left at normal pressure, 23 ° C. and 50% RH for 24 hours.

The pressure-sensitive adhesive layer of the obtained laminate was irradiated with ultraviolet rays through the polyethylene terephthalate film under the same conditions as in Test Example 2 to cure the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive layer after curing. Subsequently, it was stored for 72 hours under a high-temperature and high-humidity condition of 85 ° C. and 85% RH (endurance test). Step followability is determined by whether or not the printed step is completely filled with the post-curing adhesive layer, and bubbles, floats, peeling, etc. are observed at the interface between the printed step and the post-curing adhesive layer. It is determined that the printing step cannot be followed. Here, the step following property was evaluated as a step following rate (%) represented by the following formula. The results are shown in Table 2. In addition, when the step tracking rate of 50% cannot be satisfied, it is expressed as “X”.
Step follow-up rate (%) = {(the height of the step (μm) in which the buried state is maintained without bubbles, floats, peeling, etc. after the durability test) / (thickness of the adhesive layer: 50 μm)} × 100

[Test Example 5] (Measurement of step following rate 2)
Similar to Test Example 4, a laminate was obtained in which the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet obtained in Examples and Comparative Examples was sandwiched between the stepped glass plate and the polyethylene terephthalate film. A resin plate (Mitsubishi, Ltd.) having a polymethyl methacrylate layer and a polycarbonate layer on a polyethylene terephthalate film of the obtained laminate (which has been left for 24 hours at 23 ° C. and 50% RH after the autoclave treatment). Gas Chemical Co., Ltd. product name “Iupilon Sheet MR-58U” (thickness: 0.8 mm, containing UV absorber) was placed so that the polycarbonate layer side surface was in contact with the polyethylene terephthalate film surface. Then, the pressure-sensitive adhesive layer was irradiated with ultraviolet rays through the resin plate and the polyethylene terephthalate film under the same conditions as in Test Example 2 to cure the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive layer after curing. Thereafter, the resin plate was removed, and the same durability test and evaluation as in Test Example 4 were performed. The results are shown in Table 2.

[Test Example 6] (Evaluation of light resistance)
Using the pressure-sensitive adhesive sheet obtained in the example, a laminate was prepared in the same manner as in Test Example 3. The pressure-sensitive adhesive layer of the obtained laminate was irradiated with ultraviolet rays through the resin plate under the same conditions as in Test Example 2 to cure the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive layer after curing. After that, it was put into a light resistance tester (Suga Test Instruments Co., Ltd., product name “UV Fade Meter U48”, light source: carbon arc lamp), and irradiated with UV rays (illuminance: 50 mW / cm ² ) from the resin plate side for 100 hours. . Then, when the state of the transparent conductive film in a laminated body was confirmed visually, no change was seen in the transparent conductive film.

On the other hand, the same as in Test Example 3 except that the pressure-sensitive adhesive sheet of Comparative Example 2 was used and the resin plate was changed to a polycarbonate resin plate (product name “HMRS51T” manufactured by Mitsubishi Gas Chemical Co., Inc.) containing no UV absorber. Thus, a laminate was produced. The pressure-sensitive adhesive layer of the obtained laminate was irradiated with ultraviolet rays through the resin plate under the same conditions as in Test Example 2 to cure the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive layer after curing. After that, it was put into a light resistance tester (Suga Test Instruments Co., Ltd., product name “UV Fade Meter U48”, light source: carbon arc lamp), and irradiated with UV rays (illuminance: 50 mW / cm ² ) from the resin plate side for 100 hours. . Then, when the state of the transparent conductive film in a laminated body was confirmed visually, fading was seen in the transparent conductive film.

  As can be seen from Table 2, the pressure-sensitive adhesive layers obtained in the examples are step-following under high-temperature and high-humidity conditions as a pressure-sensitive adhesive layer after curing even when irradiated with ultraviolet rays through a resin plate containing an ultraviolet absorber. And excellent in blister resistance.

  The pressure-sensitive adhesive sheet of the present invention can be suitably used for bonding, for example, a protective panel having a step and containing a UV absorber and a desired display member constituting member.

DESCRIPTION OF SYMBOLS 1 ... Adhesive sheet 11 ... Adhesive layer 12a, 12b ... Release sheet 2 ... Display body 11 '... Adhesive layer after hardening 21 ... 1st display body structural member 22 ... 2nd display body structural member 3 ... Printing layer

Claims (8)

A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer for bonding one display body constituent member having a step to the surface to be bonded at least, and another display body structural member,
The pressure-sensitive adhesive layer is
While having a crosslinked structure composed of a (meth) acrylic acid ester copolymer (A) and a thermal crosslinking agent (B),
An ultraviolet curable component (C);
An ultraviolet curable pressure-sensitive adhesive containing a photopolymerization initiator (D) having an absorbance at a wavelength of 380 nm in an acetonitrile solution having a concentration of 0.1% by mass of 0.3 or more,
The ultraviolet curable component (C) is a polyfunctional acrylate monomer having a molecular weight of less than 1,000 ,
Content of the said ultraviolet curable component (C) in the said adhesive is 1 mass part or more and 15 mass parts or less with respect to 100 mass parts of said (meth) acrylic acid ester copolymers (A). A pressure-sensitive adhesive sheet characterized by   The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive has a gel fraction of 30% or more and 70% or less.   The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein at least one of the one display member constituting member and the other display member constituting member contains an ultraviolet absorber. The pressure-sensitive adhesive sheet includes two release sheets,
The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein the pressure-sensitive adhesive layer is sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets. It is a method for producing a pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer for bonding one display body constituting member having at least a step on the surface to be laminated, and another display body constituting member,
(Meth) acrylic acid ester copolymer (A),
A thermal crosslinking agent (B);
An ultraviolet curable component (C);
A pressure-sensitive adhesive composition containing a photopolymerization initiator (D) having an absorbance at a wavelength of 380 nm in an acetonitrile solution having a concentration of 0.1% by mass of 0.3 or more,
The ultraviolet curable component (C) is a polyfunctional acrylate monomer having a molecular weight of less than 1,000 ,
Content of the said ultraviolet curable component (C) in the said adhesive composition is 1 mass part or more and 15 mass parts or less with respect to 100 mass parts of said (meth) acrylic acid ester copolymers (A). A method for producing a pressure-sensitive adhesive sheet, characterized in that an ultraviolet curable pressure-sensitive adhesive layer is formed by applying a certain pressure-sensitive adhesive composition and thermally crosslinking. At least one display member constituting member having a step on the surface to be bonded;
Other display body components,
A display body comprising a post-curing pressure-sensitive adhesive layer that bonds the one display body constituent member and the other display body constituent member together,
The cured adhesive layer is
While having a crosslinked structure composed of a (meth) acrylic acid ester copolymer (A) and a thermal crosslinking agent (B),
A cured product of the ultraviolet curable component (C);
A pressure-sensitive adhesive containing a photopolymerization initiator (D) having an absorbance at a wavelength of 380 nm in an acetonitrile solution having a concentration of 0.1% by mass of 0.3 or more,
The ultraviolet curable component (C) is a polyfunctional acrylate monomer having a molecular weight of less than 1,000 ,
Content of the cured product of the ultraviolet curable component (C) in the post-curing pressure-sensitive adhesive layer is 1 part by mass or more and 15 parts by mass with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A). The display body characterized by being below a mass part. At least one display member constituting member having a step on the surface to be bonded;
Other display body components,
A display body comprising a post-curing pressure-sensitive adhesive layer that bonds the one display body constituent member and the other display body constituent member together,
The post-curing pressure-sensitive adhesive layer has a crosslinked structure composed of a (meth) acrylic acid ester copolymer (A) and a thermal crosslinking agent (B), and contains a cured product of an ultraviolet curable component (C). Made of adhesive
The ultraviolet curable component (C) is a polyfunctional acrylate monomer having a molecular weight of less than 1,000 ,
Content of the cured product of the ultraviolet curable component (C) in the post-curing pressure-sensitive adhesive layer is 1 part by mass or more and 15 parts by mass with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A). Less than or equal to parts by mass,
The display body, wherein the cured adhesive layer has a gel fraction of 40% to 95%. The one display body constituent member which has a level | step difference in the surface of the side by which it is bonded at least, and another display body constituent member through the adhesive layer of the adhesive sheet as described in any one of Claims 1-4. Make a laminate by pasting,
A method for producing a display body, wherein the pressure-sensitive adhesive layer of the laminate is irradiated with ultraviolet rays to cure the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive layer after curing.

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