JP6603378B2 - Indicator - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive sheet suitable for bonding display body constituent members, and a display body obtained using the pressure-sensitive adhesive sheet.

  Various mobile electronic devices such as smartphones and tablet terminals in recent years include a display using a display module having a liquid crystal element, a light emitting diode (LED element), an organic electroluminescence (organic EL) element, and the like. It is also becoming more and more a touch panel.

  In the display as described above, a protective panel is usually provided on the surface side of the display module. With the reduction in thickness and weight of electronic devices, the protective panel has been changed from a conventional glass plate to a plastic plate such as an acrylic plate or a polycarbonate plate.

  Here, a gap is provided between the protection panel and the display module so that the deformed protection panel does not collide with 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-described problem, Patent Document 1 discloses that the shear storage elastic modulus (G ′) at 25 ° C. and 1 Hz is 1.0 as an adhesive layer that fills the gap between the protective panel and the display module. × is at 10 5 ^Pa or less, and a gel fraction discloses a pressure-sensitive adhesive layer is 40% or more.

JP 2010-97070 A

  In patent document 1, it is going to improve level | step difference followability by making low the storage elastic modulus at the time of normal temperature in an adhesive layer. However, when the storage elastic modulus is lowered in such a manner, the coating strength of the pressure-sensitive adhesive layer is lowered and workability is deteriorated. For example, when the pressure sensitive adhesive sheet is punched or the like, there is a problem that the pressure sensitive adhesive adheres to the blade and a part of the pressure sensitive adhesive layer is lost. Moreover, the problem that an adhesive oozes out from an adhesive layer also arises at the time of storage of an adhesive sheet.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a pressure-sensitive adhesive sheet and a display body capable of exhibiting high film strength while the pressure-sensitive adhesive layer is excellent in step following ability. To do.

  In order to achieve the above object, first, the present invention is a pressure-sensitive adhesive for bonding one display member constituting member having a step on at least the surface to be bonded and another display member constituting member. A pressure-sensitive adhesive sheet having a layer, which was broken before reaching a 1000% modulus or an elongation of 1000% of the pressure-sensitive adhesive when the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer was subjected to a tensile test at 23 ° C. There is provided a pressure-sensitive adhesive sheet characterized in that the modulus at break is 0.22 MPa or more and the step following rate of the pressure-sensitive adhesive layer is 30% or more (Invention 1).

  The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the above invention (Invention 1) is excellent in step following ability and can exhibit high film strength.

  In the said invention (invention 1), when the tensile test is performed at 23 degreeC about the adhesive which comprises the said adhesive layer, it is preferable that the breaking elongation is 500% or more (invention 2).

  In the said invention (invention 1 and 2), it is preferable that the haze value of the said adhesive layer is 5% or less (invention 3).

  In the said invention (invention 1-3), the said adhesive sheet is equipped with the 2 release sheet, and the said adhesive layer is clamped by the said release sheet so that the peeling surface of the said 2 release sheet may be contact | connected. (Invention 4)

  2ndly, this invention is the one display body structural member which has a level | step difference at the surface by which it is bonded at least, the other display body structural member, the said 1 display body structural member, and the said other display body structural member A display body comprising a pressure-sensitive adhesive layer that is bonded to each other, wherein the pressure-sensitive adhesive layer is a pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (Invention 1 to 4). Invention 5).

  The pressure-sensitive adhesive sheet and the pressure-sensitive adhesive layer of the display body according to the present invention have excellent step following ability and can exhibit high film strength.

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 embodiment of this invention has an adhesive layer for bonding one display body structural member which has a level | step difference in the surface of the side bonded together, and another display body structural member. In addition, a display body and a display body structural member are mentioned later.

1. Physical Properties (1) Modulus 1000% modulus of the pressure-sensitive adhesive when the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is subjected to a tensile test at 23 ° C. (modulus at break when it breaks before reaching an elongation of 1000%; Hereinafter, it may simply be referred to as “modulus at break”) is 0.22 MPa or more as a lower limit, preferably 0.25 MPa or more, and particularly preferably 0.27 MPa or more. When the lower limit of the above-mentioned 1000% modulus (or the modulus at break) is 0.22 MPa or more, the coating strength as the pressure-sensitive adhesive layer is high and the processability is excellent. For example, when the pressure sensitive adhesive sheet is punched or the like, it is possible to suppress the occurrence of a problem that the pressure sensitive adhesive adheres to the blade and a part of the pressure sensitive adhesive layer is lost. Moreover, it is suppressed that an adhesive oozes out from an adhesive layer at the time of storage of an adhesive sheet, etc.

  The upper limit value of the above-mentioned 1000% modulus (or the modulus at break) is not particularly limited, but usually it is preferably 2.0 MPa or less, particularly preferably 1.0 MPa or less, and the step following rate can be further increased. From the viewpoint of excellent performance, it is more preferably 0.50 MPa or less. Here, the detail of the said tension test is as showing to the test example mentioned later.

(2) Step following property The pressure sensitive adhesive layer of the pressure sensitive adhesive sheet according to this embodiment has a step following rate (%) represented by the following formula of 30% or more as a lower limit, preferably 40% or more, Particularly preferably, it is 50% or more. On the other hand, the upper limit value of the step tracking 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
The predetermined durability test is a test in which the sample is stored at 85 ° C. and 85% RH for 72 hours, and a specific test method for the step following rate is as shown in a test example described later.

  When the pressure-sensitive adhesive layer has a step following rate within the above range, when the pressure-sensitive adhesive sheet according to the present embodiment is attached to a display member having a step, the pressure-sensitive adhesive layer easily follows the step and is near the step. The occurrence of gaps, floats, etc. is suppressed. Moreover, even when it is placed in a high-temperature and high-humidity condition, for example, 85 ° C. and 85% RH for 72 hours in this state, the occurrence of bubbles, floating, peeling, etc. in the vicinity of the step is suppressed. Thereby, in the obtained display body, it is suppressed that the reflection loss of light arises.

  As described above, the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the present embodiment has both contradictory physical properties of high film strength and excellent step following ability.

(3) Breaking Elongation About the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, the breaking elongation when a tensile test is performed at 23 ° C. is preferably 500% or more, and particularly preferably 800% or more. Preferably, it is more preferably 1000% or more, and most preferably 1200% or more. When the breaking elongation is 500% or more, the pressure-sensitive adhesive layer easily satisfies the step difference rate described above.

  The upper limit of the elongation at break is not particularly limited, but is usually preferably 3000% or less, and particularly preferably 2000% or less. Here, the tensile test for breaking elongation is based on the same method as the above-described tensile test for 1000% modulus (or modulus at break).

(4) Adhesive strength The adhesive strength of the adhesive sheet according to the present embodiment to soda lime glass is preferably 5 N / 25 mm or more as a lower limit, particularly preferably 10 N / 25 mm or more, and more preferably 15 N / 25 mm. The above is preferable. When the adhesive strength of the adhesive sheet 1 is 5 N / 25 mm or more, the step following ability under high temperature and high humidity becomes more excellent. Moreover, it is preferable that the adhesive strength with respect to soda-lime glass of the adhesive sheet which concerns on this embodiment is 50 N / 25mm or less as an upper limit, It is more preferable that it is 40 N / 25mm or less, It is 35 N / 25mm or less. Particularly preferred is 25 N / 25 mm or less. When the adhesive strength of the adhesive sheet 1 is 50 N / 25 mm or less, it is possible to prevent the adhesive from adhering to the blade during cutting, and when it is 25 N / 25 mm or less, good reworkability is obtained. When a bonding mistake occurs, the expensive display member constituting member can be reused.

  Here, the adhesive force basically means an adhesive force measured by a 180 degree peeling method according to JIS Z0237: 2009. The measurement sample has a width of 25 mm and a length of 100 mm, and the measurement sample is attached to the adherend. After being applied to the substrate and pressurized at 0.5 MPa and 50 ° C. for 20 minutes, the sample is left at normal pressure, 23 ° C. and 50% RH for 24 hours, and then measured at a peeling rate of 300 mm / min. .

(5) Wet heat adhesive force The adhesive force (referred to as “wet heat adhesive force” in the present specification) of the pressure-sensitive adhesive sheet according to the present embodiment on soda-lime glass is preferably 5 N / 25 mm or more as a lower limit. In particular, it is preferably 10 N / 25 mm or more, more preferably 15 N / 25 mm or more. When the wet heat adhesive force of the pressure-sensitive adhesive sheet 1 is 5 N / 25 mm or more, the step following property under high temperature and high humidity becomes more excellent. In addition, the wet heat adhesive strength of the pressure-sensitive adhesive sheet according to the present embodiment to soda lime glass is preferably 50 N / 25 mm or less as an upper limit, more preferably 40 N / 25 mm or less, and 30 N / 25 mm or less. Is particularly preferable, and more preferably 25 N / 25 mm or less. When the wet heat adhesive force of the pressure-sensitive adhesive sheet 1 is 50 N / 25 mm or less, it is possible to prevent the pressure-sensitive adhesive from adhering to the blade during cutting, and when it is 25 N / 25 mm or less, good reworkability is obtained. When a bonding mistake occurs, the expensive display member constituting member can be reused.

  Here, the wet heat adhesive force basically means an adhesive force measured by a 180-degree peeling method according to JIS Z0237: 2009. The measurement sample has a width of 25 mm and a length of 100 mm. Affixed to the body, pressurized at 0.5 MPa and 50 ° C. for 20 minutes, then left for 24 hours under conditions of 60 ° C. and 90% RH, and then for 24 hours under conditions of normal pressure, 23 ° C. and 50% RH It is assumed that the measurement is performed at a peeling speed of 300 mm / min after being left standing.

(6) Haze value The haze value of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to this embodiment is preferably 5% or less, more preferably 3% or less, and particularly preferably 1% or less, More preferably, it is 0.7% or less. When the haze value of the pressure-sensitive adhesive layer is 5% or less, the transparency is very high, which is suitable for optical applications (for display bodies). The haze value in this specification is a value measured according to JIS K7136: 2000.

2. The pressure-sensitive adhesive layer The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the present embodiment satisfies the above-mentioned 1000% modulus (or modulus at break) and step followability, and preferably further includes the above-described elongation at break, adhesive strength, and wet heat adhesion. It is comprised by the adhesive which satisfy | fills force and a haze value.

  Such a pressure-sensitive adhesive contains a hydroxyl group-containing monomer (a monomer containing a hydroxyl group in the molecule) and an alicyclic structure-containing monomer (a monomer containing an alicyclic structure in the molecule) as monomer units constituting the polymer ( An adhesive composition containing a (meth) acrylic acid ester polymer (A), a polyrotaxane compound (B) having a cyclic oligosaccharide as a cyclic molecule, and an isocyanate crosslinking agent (C) (hereinafter referred to as “adhesive composition P”) Can be preferably obtained by crosslinking. However, the present invention is not limited to this.

  In the present specification, (meth) acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms. Further, the “polymer” includes the concept of “copolymer”.

  When the pressure-sensitive adhesive composition P is crosslinked, the hydroxyl group derived from the hydroxyl group-containing monomer in the (meth) acrylic ester polymer (A) reacts with the isocyanate group of the isocyanate-based crosslinking agent (C) to form a three-dimensional network structure. And a pressure-sensitive adhesive having a predetermined cohesive force is obtained. The polyrotaxane compound (B) has a mechanical bond between a cyclic molecule and a linear molecule penetrating the cyclic molecule, and the cyclic molecule can freely move on the linear molecule. With this structure, the polyrotaxane compound (B) can impart excellent stress relaxation properties to the resulting pressure-sensitive adhesive. In addition, since the alicyclic structure-containing monomer is bulky, it is presumed that the presence of the alicyclic structure-containing monomer in the polymer widens the distance between the polymers, and the resulting pressure-sensitive adhesive has excellent flexibility. Can do. Therefore, the adhesive composition P contains the polyrotaxane compound (B), and the (meth) acrylic acid ester polymer (A) uses the alicyclic structure-containing monomer as a constituent monomer unit. The pressure-sensitive adhesive obtained by cross-linking is excellent in step followability, and can satisfy the step followability value described above.

  Since the above excellent step following property can be obtained without lowering the storage elastic modulus of the pressure-sensitive adhesive, the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition P has a high film strength. And the above-mentioned value of 1000% modulus (or modulus at break) can be satisfied.

  Here, in the case where the cyclic molecule of the polyrotaxane compound (B) is a cyclic oligosaccharide having a hydroxyl group as a reactive group, the following effects are particularly obtained. That is, when the adhesive composition P is crosslinked, the isocyanate group of the isocyanate-based crosslinking agent (C) reacts with the hydroxyl group derived from the hydroxyl group-containing monomer in the (meth) acrylic acid ester polymer (A), and the isocyanate group. The isocyanate group of the crosslinking agent (C) reacts with the hydroxyl group of the cyclic molecule of the polyrotaxane compound (B). As a result, the (meth) acrylic acid ester polymer (A) is bonded to one cyclic molecule of the polyrotaxane compound (B) via the isocyanate-based crosslinking agent (C) by a hydroxyl group, and similarly to another (meth) It is presumed that the acrylate polymer (A) binds to another cyclic molecule of the polyrotaxane compound (B). As a result, a plurality of (meth) acrylic acid ester polymers (A) are presumed to form higher order structures such as a three-dimensional network structure that are mechanically bonded to each other by the polyrotaxane compound (B). With this higher order structure, the film strength is higher without deteriorating stress relaxation properties (without step following ability) as compared with the same higher order structure except that the polyrotaxane compound (B) is not included. can do.

  In addition, it is not necessary that all of the obtained pressure-sensitive adhesives have the above-mentioned estimated structure, and the two (meth) acrylic acid ester polymers (A) do not go through the polyrotaxane compound (B), and the isocyanate-based crosslinking agent (C). The structure etc. which are couple | bonded directly by may be included.

(1) (Meth) acrylic acid ester polymer (A)
The (meth) acrylic acid ester polymer (A) preferably contains a hydroxyl group-containing monomer and an alicyclic structure-containing monomer as monomer units constituting the polymer.

  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 them, from the viewpoint of the reactivity of the hydroxyl group in the resulting (meth) acrylic acid ester polymer (A) with the isocyanate-based crosslinking agent (C) and copolymerization with other monomers, (meth) acrylic acid 2- Hydroxyethyl or 4-hydroxybutyl (meth) acrylate is preferred. These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester polymer (A) preferably contains a hydroxyl group-containing monomer as a lower limit of 3% by mass or more, particularly 5% by mass or more, as a monomer unit constituting the polymer. More preferably, it is preferably contained in an amount of 10% by mass or more. When the content of the hydroxyl group-containing monomer is 3% by mass or more, the cohesive force of the obtained pressure-sensitive adhesive is improved, and thereby the coating strength is higher. The (meth) acrylic acid ester polymer (A) preferably contains a hydroxyl group-containing monomer as an upper limit of 30% by mass or less, particularly 25% by mass or less, as a monomer unit constituting the polymer. It is preferable to contain 20% by mass or less. When the content of the hydroxyl group-containing monomer is 30% by mass or less, appropriate tackiness is easily obtained, and the pressure-sensitive adhesive is prevented from becoming too hard, and the step following ability is further improved.

  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 making the distance between the obtained (meth) acrylic acid ester polymer (A) appropriate and imparting high stress relaxation properties to the pressure-sensitive adhesive, the alicyclic structure is a polycyclic alicyclic structure ( A polycyclic structure). Furthermore, considering the compatibility between the (meth) acrylic acid ester polymer (A) and other components, the polycyclic structure is particularly preferably bicyclic to tetracyclic. In addition, from the viewpoint of imparting stress relaxation properties as described above, the carbon number of the alicyclic structure (refers to the total number of carbon atoms of the portion forming the ring, and when multiple rings exist independently) , Which means the total number of carbon atoms) is usually preferably 5 or more, and 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.

  Specific examples of the alicyclic structure-containing monomer include cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, adamantyl (meth) acrylate, isobornyl (meth) acrylate, and (meth) acrylic. Dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, etc., among others, (meth) acrylic acid dicyclopentanyl (alicyclic structure) that exhibits better step following ability under wet heat conditions Is preferably 10), adamantyl (meth) acrylate (carbon number of alicyclic structure: 10) or isobornyl (meth) acrylate (carbon number of alicyclic structure: 7), particularly (meth) acrylic. Isobornyl acid is preferred. These may be used individually by 1 type and may be used in combination of 2 or more type.

  The (meth) acrylic acid ester polymer (A) preferably contains 1% by mass or more, and particularly preferably 5% by mass or more, of the alicyclic structure-containing monomer as a monomer unit constituting the polymer. Furthermore, it is preferable to contain 10% by mass or more. Further, the (meth) acrylic acid ester polymer (A) preferably contains 50% by mass or less of the alicyclic structure-containing monomer as the monomer unit constituting the polymer, particularly 40% by mass or less. It is preferable to contain 30% by mass or less. When the content of the alicyclic structure-containing monomer is within the above range, the resulting pressure-sensitive adhesive is more excellent in level-step following property and sufficiently exhibits excellent adhesion to the transparent conductive film and plastic.

  In the (meth) acrylic acid ester polymer (A), as a monomer unit constituting the polymer, in addition to the hydroxyl group-containing monomer and the alicyclic structure-containing monomer, the alkyl group has 5 to 20, particularly 8 to 8 carbon atoms. It is preferable to contain 15 (meth) acrylic-acid alkylesters (thing which does not contain an alicyclic structure). Thereby, preferable adhesiveness can be expressed, without reducing compatibility with a polyrotaxane compound (B). Moreover, a softness | flexibility can be provided to the adhesive obtained and the level | step difference followability can be made excellent. The alkyl group may be linear or branched.

  From the above viewpoint, the (meth) acrylic acid ester polymer (A) is 10% by mass or more of (meth) acrylic acid alkyl ester having 5 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. It is preferably contained, particularly preferably 20% by mass or more, and more preferably 50% by mass or more. When the said (meth) acrylic-acid alkylester is contained 10 mass% or more, the obtained adhesive can exhibit suitable adhesiveness and more excellent level | step difference followable | trackability. Moreover, (meth) acrylic acid ester polymer (A) contains 90 mass% or less of (meth) acrylic acid alkyl ester whose carbon number of an alkyl group is 5-20 as a monomer unit which comprises the said polymer. In particular, it is preferably contained in an amount of 80% by mass or less, more preferably 70% by mass or less. By setting the (meth) acrylic acid alkyl ester to 90% by mass or less, a suitable amount of other monomer components can be introduced into the (meth) acrylic acid ester polymer (A).

  Examples of the (meth) acrylic acid alkyl ester having 5 to 20 carbon atoms in the alkyl group include, for example, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, ( Examples include isooctyl (meth) acrylate, n-decyl (meth) acrylate, n-dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, and the like. Among them, 2-ethylhexyl (meth) acrylate is preferable from the viewpoint of further improving the adhesiveness and compatibility with the polyrotaxane compound (B). These may be used alone or in combination of two or more.

  On the other hand, the (meth) acrylic acid ester polymer (A) does not contain a (meth) acrylic acid alkyl ester having 4 or less carbon atoms as the monomer unit constituting the polymer, or less than 60% by mass. It is also preferable to contain it in an amount of preferably 50% by mass or less, particularly preferably 30% by mass or less. Thereby, a suitable quantity of another monomer component can be introduce | transduced in a (meth) acrylic acid ester polymer (A).

  The (meth) acrylic acid ester polymer (A) also preferably contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer. By having a nitrogen atom-containing monomer as a structural unit in the polymer, the adhesive is given a certain polarity and has excellent affinity for adherends having a certain degree of polarity such as glass. It can be. Examples of the nitrogen atom-containing monomer include a monomer having an amino group, a monomer having an amide group, a monomer having a nitrogen-containing heterocyclic ring, etc. Among them, the (meth) acrylate polymer (A) has an appropriate rigidity. From the viewpoint of imparting, a monomer having a nitrogen-containing heterocyclic ring 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 nitrogen atom-containing monomers include (meth) acrylamide, N-methyl (meth) acrylamide, N-methylol (meth) acrylamide, N-tert-butyl (meth) acrylamide, and 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-vinyl Caprolactam, monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate, dimethylamino (meth) acrylate It is also possible to use the chill and the like.
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 polymer (A) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer, the nitrogen atom-containing monomer is preferably contained in an amount of 0.5% by mass or more. The content is preferably 1% by mass or more, and more preferably 3% by mass or more. Further, the (meth) acrylic acid ester polymer (A) preferably contains 20% by mass or less of the nitrogen atom-containing monomer as a monomer unit constituting the polymer, and particularly 15% by mass or less. More preferably, the content is preferably 8% by mass or less. When the content of the nitrogen atom-containing monomer is within the above range, the obtained pressure-sensitive adhesive can sufficiently exhibit excellent adhesion to glass.

  Further, the (meth) acrylic acid ester polymer (A) preferably contains a hard monomer having a glass transition temperature (Tg) as a homopolymer of 0 ° C. or more as a monomer unit constituting the polymer. In addition, the various monomers mentioned above can also be contained in this hard monomer. By including the hard monomer as a monomer unit constituting the (meth) acrylic acid ester polymer (A), the resulting pressure-sensitive adhesive has a higher cohesive force and higher film strength. In particular, as a monomer unit constituting the (meth) acrylic acid ester polymer (A), a (meth) acrylic acid alkyl ester having an alkyl group having 5 to 20 carbon atoms (for example, (meth) acrylic acid 2-ethylhexyl) is used. When used, since the cohesive force tends to be low, it is preferable to use the hard monomer. The glass transition temperature (Tg) as a homopolymer of the hard monomer is preferably 15 ° C. or higher, and particularly preferably 80 ° C. or higher, as a lower limit. Further, the glass transition temperature (Tg) is preferably 200 ° C. or lower as an upper limit, and particularly preferably 180 ° C. or lower.

  Examples of the hard monomer include methyl acrylate (Tg 10 ° C.), methyl methacrylate (Tg 105 ° C.), isobornyl acrylate (Tg 94 ° C.), isobornyl methacrylate (Tg 180 ° C.), adamantyl acrylate (Tg 115 ° C.), and methacrylic acid. Examples thereof include adamantyl (Tg 141 ° C.), acryloylmorpholine (Tg 145 ° C.), cyclohexyl acrylate (Tg 19 ° C.), and the like. These may be used alone or in combination of two or more.

  When the (meth) acrylic acid ester polymer (A) contains the hard monomer as a monomer unit constituting the polymer, the hard monomer is preferably contained in an amount of 5% by mass or more, and is preferably contained in an amount of 10% by mass or more. It is particularly preferred. By containing 5% by mass or more of the hard monomer, the coating strength can be further improved. The (meth) acrylic acid ester polymer (A) preferably contains 40% by mass or less, and particularly preferably 30% by mass or less, of the hard monomer as a monomer unit constituting the polymer. By setting the hard monomer content to 40% by mass or less, the relative shortage of other monomer units in the (meth) acrylic acid ester polymer (A) is prevented, and the pressure-sensitive adhesive of the resulting pressure-sensitive adhesive In addition, the step following ability can be improved.

  The (meth) acrylic acid ester polymer (A) may contain other monomers as monomer units constituting the polymer, if desired. The other monomer may be a monomer containing a reactive functional group (excluding a hydroxyl group) or a monomer not containing a reactive functional group.

  Preferred examples of the monomer containing a reactive functional group include a carboxy group-containing monomer. 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. Among these, acrylic acid is preferable from the viewpoint of the influence on the reaction between the hydroxyl group derived from the hydroxyl group-containing monomer and the isocyanate-based crosslinking agent (C) and the copolymerizability with other monomers. These may be used alone or in combination of two or more.

  When the (meth) acrylic acid ester polymer (A) contains a carboxy group-containing monomer as a monomer unit constituting the polymer, the content is preferably 0.5% by mass or more as a lower limit, In particular, it is preferably 1% by mass or more. Moreover, as an upper limit, it is preferable that it is 20 mass% or less, and it is especially preferable that it is 10 mass% or less.

  In addition, from the viewpoint of facilitating control of the crosslinked structure of the obtained pressure-sensitive adhesive, it is also preferable to use only the above-mentioned hydroxyl group-containing monomer as the monomer containing a reactive functional group.

  On the other hand, examples of the monomer containing no reactive functional group include (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, vinyl acetate, and styrene. It is done. These may be used alone or in combination of two or more.

  The polymerization mode of the (meth) acrylic acid ester polymer (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 acid ester polymer (A) may be used alone or in combination of two or more.

(2) Polyrotaxane compound (B)
The polyrotaxane compound (B) is a compound in which a linear molecule penetrates through openings of at least two cyclic molecules and has a blocking group at both ends of the linear molecule. In this polyrotaxane compound (B), the cyclic molecule can freely move on the linear molecule, but the cyclic molecule has a structure in which the cyclic molecule cannot escape from the linear molecule due to the blocking group. That is, the linear molecule and the cyclic molecule maintain their forms not by chemical bonds such as covalent bonds but by so-called mechanical bonds. When the pressure-sensitive adhesive composition P contains the polyrotaxane compound (B) having such a mechanical bond, the obtained pressure-sensitive adhesive has a 1000% modulus (or a modulus at break) without lowering the stress relaxation property. improves. As a result, the pressure-sensitive adhesive layer has enhanced film strength and excellent workability.

  The polyrotaxane compound (B) preferably has a cyclic oligosaccharide as a cyclic molecule. By using a cyclic oligosaccharide as the cyclic molecule of the polyrotaxane compound (B), it becomes possible to select an appropriate ring diameter, and thereby the effect due to the movement of the cyclic molecule on the linear molecule is easily exhibited. Moreover, when the said cyclic oligosaccharide has a hydroxyl group as a reactive group, reaction with an isocyanate type crosslinking agent (C) is easy. Furthermore, introduction of various substituents and the like is easy, whereby the compatibility between the polyrotaxane compound (B) and other components can be adjusted by the polyrotaxane compound (B). Furthermore, if it is cyclic oligosaccharide, there also exists an advantage that acquisition is easy. In the present specification, “cyclic” of “cyclic molecule” or “cyclic oligosaccharide” means substantially “cyclic”. In other words, the cyclic molecule may not be completely closed as long as it can move on the linear molecule, and may have a helical structure, for example.

  Preferred cyclic oligosaccharides include cyclodextrins such as α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin, and among them, α-cyclodextrin is particularly preferable. Two or more kinds of cyclic molecules of the polyrotaxane compound (B) may be mixed in the polyrotaxane compound (B) or in the adhesive composition P.

  When the cyclic molecule (cyclic oligosaccharide) of the polyrotaxane compound (B) has a hydroxyl group as a reactive group, the hydroxyl group may be a hydroxyl group that the cyclic oligosaccharide originally has (refers to a state before modification). Further, it may be a hydroxyl group introduced as a substituent into the cyclic oligosaccharide.

  The lower limit of the hydroxyl value of the cyclic molecule is preferably 10 mgKOH / g or more, more preferably 30 mgKOH / g or more, and particularly preferably 50 mgKOH / g or more. A polyrotaxane compound (B) can fully react with an isocyanate type crosslinking agent (C) as the lower limit of a hydroxyl value is more than the above. In addition, the upper limit of the hydroxyl value of the cyclic molecule is preferably 1000 mgKOH / g or less, more preferably 200 mgKOH / g or less, and particularly preferably 100 mgKOH / g or less. When the upper limit of the hydroxyl value exceeds the above value, a large number of crosslinks occur in the same cyclic molecule, so that the cyclic molecule itself becomes a crosslink point, and the effect of the crosslink point as the whole polyrotaxane compound (B) can be exhibited. It is thought that it will disappear. As a result, it is conceivable that the effect of improving the film strength is not sufficient while the step followability is maintained as it is due to the addition of the polyrotaxane compound (B).

  The linear molecule of the polyrotaxane compound (B) is a molecule or substance that is included in a cyclic molecule and can be integrated by mechanical bonds rather than chemical bonds such as covalent bonds, and is linear If it is, it will not be specifically limited. In the present specification, “linear” of “linear molecule” means substantially “linear”. That is, the linear molecule may have a branched chain as long as the cyclic molecule can move on the linear molecule.

  As the linear molecule of the polyrotaxane compound (B), for example, polyethylene glycol, polypropylene glycol, polyisoprene, polyisobutylene, polybutadiene, polytetrahydrofuran, polyacrylic acid ester, polydimethylsiloxane, polyethylene, polypropylene and the like are preferable. Two or more kinds of linear molecules may be mixed in the adhesive composition P.

  The number average molecular weight of the linear molecule of the polyrotaxane compound (B) is preferably 3,000 or more as a lower limit, particularly preferably 10,000 or more, and more preferably 20,000 or more. preferable. When the lower limit of the number average molecular weight is not less than the above, the amount of movement of the cyclic molecule on the linear molecule is secured, and the stress relaxation property of the pressure-sensitive adhesive is sufficiently obtained. The number average molecular weight of the linear molecule of the polyrotaxane compound (B) is preferably 300,000 or less, particularly preferably 200,000 or less, more preferably 100,000 or less, as an upper limit. It is preferable. When the upper limit of the number average molecular weight is not more than the above, the solubility of the polyrotaxane compound (B) in the solvent and the compatibility with the (meth) acrylic acid ester polymer (A) are improved.

  The blocking group of the polyrotaxane compound (B) is not particularly limited as long as the cyclic molecule is a group that can maintain a skewered form with a linear molecule. Examples of such groups include bulky groups and ionic groups.

  Specifically, the blocking group of the polyrotaxane compound (B) may be a dinitrophenyl group, a cyclodextrin, an adamantane group, a trityl group, a fluorescein, a pyrene, an anthracene, or the like, or a number average molecular weight of 1,000. A polymer main chain or side chain of ˜1,000,000 is preferred, and two or more of these blocking groups may be mixed in the polyrotaxane compound (B) or the adhesive composition P.

  The polyrotaxane compound (B) described above can be obtained by a conventionally known method (for example, the method described in JP-A-2005-154675).

  The content of the polyrotaxane compound (B) in the adhesive composition P is preferably 3 parts by mass or more as a lower limit with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A), particularly 5 The amount is preferably at least part by mass, and more preferably at least 7 parts by mass. When the content of the polyrotaxane compound (B) is 3 parts by mass or more, the 1000% modulus (or modulus at break) of the obtained pressure-sensitive adhesive increases, and the processability becomes more excellent. Further, when the content of the polyrotaxane compound (B) is 7 parts by mass or more, the step following property of the obtained pressure-sensitive adhesive is further improved. Further, the content of the polyrotaxane compound (B) is preferably 30 parts by mass or less as an upper limit, more preferably 25 parts by mass or less, particularly preferably 20 parts by mass or less, and 15 parts by mass. More preferably, it is as follows. When the content of the polyrotaxane compound (B) is 30 parts by mass or less, the workability of the obtained pressure-sensitive adhesive becomes better and the compatibility with the (meth) acrylate polymer (A) is good. The haze value of the pressure-sensitive adhesive obtained can be kept low. Further, when the content of the polyrotaxane compound (B) is 15 parts by mass or less, the step following property of the obtained pressure-sensitive adhesive is further improved.

(3) Isocyanate-based crosslinking agent (C)
The isocyanate-based crosslinking agent (C) is reactive with the hydroxyl group derived from the hydroxyl group-containing monomer in the (meth) acrylic ester polymer (A) and the hydroxyl group of the cyclic oligosaccharide that is a cyclic molecule of the polyrotaxane compound (B). Excellent.

  The isocyanate-based crosslinking agent (C) 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. In addition, an isocyanate type crosslinking agent (C) can be used individually by 1 type or in combination of 2 or more types.

  The content of the isocyanate-based crosslinking agent (C) in the adhesive composition P is 0.05 parts by mass or more as a lower limit value with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A). Particularly, it is preferably 0.1 parts by mass or more, and more preferably 0.2 parts by mass or more. It is presumed that the above-mentioned higher order structure can be satisfactorily formed when the lower limit value of the content of the isocyanate-based crosslinking agent (C) is not less than the above, and the level difference of the obtained pressure-sensitive adhesive under high temperature and high humidity The follow-up property becomes better. Moreover, it is preferable that content of isocyanate type crosslinking agent (C) is 3 mass parts or less as an upper limit with respect to 100 mass parts of (meth) acrylic acid ester polymer (A), and especially 2 mass parts or less. It is preferable that it is 1 mass part or less. When the upper limit value of the content of the isocyanate-based crosslinking agent (C) is not more than the above, it is possible to make the degree of crosslinking moderate and to ensure good step-following property of the obtained pressure-sensitive adhesive.

(4) Various additives For the adhesive composition P, various additives usually used for acrylic pressure-sensitive adhesives, for example, silane coupling agents, reaction accelerators, reaction inhibitors, ultraviolet absorbers, and electrifications, as desired. An inhibitor, a tackifier, an antioxidant, a light stabilizer, 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.

  As the silane coupling agent, an organosilicon compound having at least one alkoxysilyl group in the molecule, having good compatibility with the (meth) acrylic acid ester polymer (A), and having light transmittance. preferable.

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

  When the adhesive composition P contains a silane coupling agent, the content thereof is 0.01 parts by mass or more as a lower limit with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A). In particular, it is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more. Further, the content of the silane coupling agent is preferably 1 part by mass or less as an upper limit, particularly preferably 0.5 part by mass or less, and more preferably 0.3 part by mass or less. preferable.

(5) Manufacture of adhesive composition The adhesive composition P manufactured the (meth) acrylic acid ester polymer (A), the obtained (meth) acrylic acid ester polymer (A), the polyrotaxane compound ( While mixing B) and an isocyanate type crosslinking agent (C), it can manufacture by adding an additive if desired.

  The (meth) acrylic acid ester polymer (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 polymer (A) is preferably carried out by a solution polymerization method using a polymerization initiator if 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 2,2′-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 polymer (A) is obtained, the polyrotaxane compound (B), the isocyanate-based crosslinking agent (C), and, if desired, a diluting solvent are added to the solution of the (meth) acrylic acid ester polymer (A). Then, an adhesive composition P (coating solution) diluted with a solvent is obtained by adding and mixing the additives. When any of the above components is used in a solid state or when precipitation occurs when mixed with other components in an undiluted state, the component is used alone as a dilution solvent. It may be dissolved or diluted and then mixed with other components.

  Examples of the dilution solvent include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, methanol, ethanol, propanol, butanol, Alcohols such as 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone, and cyclohexanone, esters such as ethyl acetate and butyl acetate, and cellosolve solvents such as ethyl cellosolve are used.

  The concentration / viscosity of the coating solution thus prepared is not particularly limited as long as it can be coated, and can be appropriately selected depending on the situation. For example, it dilutes so that the density | concentration of the adhesive composition P may be 10-60 mass%. In addition, when obtaining a coating solution, addition of a dilution solvent etc. is not a necessary condition, and if a viscosity etc. which can be coated with the adhesive composition P are not necessary, a dilution solvent does not need to be added. In this case, the adhesive composition P becomes a coating solution using the polymerization solvent of the (meth) acrylic acid ester polymer (A) as a dilution solvent.

(6) Production of pressure-sensitive adhesive By crosslinking the pressure-sensitive adhesive composition P, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to this embodiment can be preferably obtained. The crosslinking of the pressure-sensitive adhesive composition P can be usually performed by heat treatment. In addition, this heat processing can also serve as the drying process at the time of volatilizing a dilution solvent etc. from the coating film of the adhesive composition P apply | coated to the desired target object.

  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.

  After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be provided at room temperature (for example, 23 ° C., 50% RH). When this curing period is necessary, after the curing period has elapsed, and when the curing period is unnecessary, an adhesive is formed after the heat treatment.

  By the heat treatment (and curing), the (meth) acrylic acid ester polymer (A) (and the polyrotaxane compound (B)) is sufficiently crosslinked through the isocyanate crosslinking agent (C). Thus, the obtained adhesive is excellent in level | step difference followability, and can exhibit high film strength.

(7) Gel fraction of adhesive The gel fraction of the adhesive which comprises the adhesive layer of the adhesive sheet which concerns on this embodiment, especially the adhesive obtained from the adhesive composition P is 40% or more as a lower limit. Preferably, it is 45% or more, more preferably 50% or more, and even more preferably 60% or more. When the lower limit of the gel fraction of the pressure-sensitive adhesive is not less than the above, the cohesive force of the pressure-sensitive adhesive is increased, and the coating strength of the pressure-sensitive adhesive layer is higher. Further, the gel fraction of the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition P is preferably 90% or less as an upper limit, particularly preferably 85% or less, and more preferably 80% or less. . When the upper limit of the gel fraction of the pressure-sensitive adhesive is not more than the above, the pressure-sensitive adhesive does not become too hard, and the step following property of the pressure-sensitive adhesive layer becomes more excellent. Here, the measuring method of the gel fraction of an adhesive is as showing to the test example mentioned later.

(8) Thickness of the pressure-sensitive adhesive layer The thickness of the pressure-sensitive adhesive layer in the pressure-sensitive adhesive sheet according to this embodiment (value measured according to JIS K7130) is preferably 10 μm or more as a lower limit, and is 25 μm or more. More preferably, it is particularly preferably 50 μm or more. When the lower limit value of the thickness of the pressure-sensitive adhesive layer 11 is equal to or greater than the above, it is easy to exert a desired adhesive force, and it is possible to ensure sufficient step following performance with respect to a normal step of the display member constituting member. . The thickness of the pressure-sensitive adhesive layer 11 is preferably 1000 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.

3. Specific Configuration of Adhesive Sheet FIG. 1 shows a specific configuration as an example of the adhesive sheet according to the present embodiment.
As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 according to an embodiment includes two release sheets 12a and 12b and the two release sheets 12a so as to be in contact with the release surfaces of the two release sheets 12a and 12b. , 12b and an adhesive layer 11 sandwiched between the two layers. 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) Adhesive layer The adhesive layer 11 is comprised from the adhesive which satisfy | fills the physical property mentioned above, Preferably, it is comprised from the adhesive formed by bridge | crosslinking the adhesive composition P. FIG.

(2) Release sheet The release sheets 12a and 12b protect the pressure-sensitive adhesive layer 11 until the pressure-sensitive adhesive sheet 1 is used, and are peeled off when the pressure-sensitive adhesive sheet 1 (pressure-sensitive adhesive layer 11) is used. In the pressure-sensitive adhesive sheet 1 according to this embodiment, one or both of the release sheets 12a and 12b are not necessarily required.

  Examples of the release sheets 12a and 12b include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, and 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, fluorine A resin 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) Production of pressure-sensitive adhesive sheet As one 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 (or 12b), and heat treatment is performed for adhesion. After heat-crosslinking property composition P and forming a coating layer, the peeling surface of the other peeling sheet 12b (or 12a) is piled up 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.

  In the pressure-sensitive adhesive sheet 1 according to this embodiment, since the coating strength of the pressure-sensitive adhesive layer 11 is high, when the pressure-sensitive adhesive sheet 1 is punched, the pressure-sensitive adhesive adheres to the blade and a part of the pressure-sensitive adhesive layer 11 is missing. Occurrence of problems such as the occurrence of problems 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 pressure-sensitive adhesive layer 11 that is located between them and bonds the first display body constituent member 21 and the second display body constituent member 22 to each other. It is prepared for. In the display body 2 according to the present embodiment, the first display body constituting member 21 has a step on the surface on the pressure-sensitive adhesive layer 11 side, and specifically has a step due to the printing layer 3. .

  The pressure-sensitive adhesive layer 11 in the display body 2 is the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 described above.

  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 printing layer 3 is generally formed in a frame shape on the pressure-sensitive adhesive layer 11 side in the first display member constituting member 21.

  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.

  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 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 is less than or equal to the above, it is possible to prevent deterioration in the step following ability of the pressure-sensitive adhesive layer 11 with respect to the print layer 3.

  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 level difference followability, it is possible to suppress the occurrence of gaps and floating in the vicinity of the level difference due to the printing layer 3.

  Then, the other peeling 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. 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.

  In the above display body 2, since the pressure-sensitive adhesive layer 11 is excellent in step following property even under high temperature and high humidity conditions, the display body 2 is placed under high temperature and high humidity conditions (for example, 85 ° C., 85% RH). Even in this case, the occurrence of bubbles, floating, peeling, etc. in the vicinity of the step is suppressed.

  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 or both of the release sheets 12a and 12b in the pressure-sensitive adhesive sheet 1 may be omitted, and a desired optical member may be laminated instead of the release sheets 12a and / or 12b. Further, the first display member constituting member 21 may have a step other than the printed layer 3. Furthermore, not only the 1st display body structural member 21, but the 2nd display body structural member 22 may also have a level | step difference in the 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 polymer 60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of isobornyl acrylate, 5 parts by mass of 4-acryloylmorpholine and 15 parts by mass of 2-hydroxyethyl acrylate are copolymerized ( A (meth) acrylic acid ester polymer (A) was prepared. When the molecular weight of this (meth) acrylic acid ester polymer (A) was measured by the method described later, it was a weight average molecular weight (Mw) of 600,000.

2. Preparation of Adhesive Composition 100 parts by mass of the (meth) acrylic acid ester polymer (A) obtained in Step 1 above (converted to a solid content; the same applies hereinafter) and a polyrotaxane compound (B) (Advanced Soft Materials, Inc.) Manufactured, product name “Celum Superpolymer SH3400P”, linear molecule: polyethylene glycol, cyclic molecule: α-cyclodextrin having hydroxypropyl group and caprolactone chain, block group: adamantane group, weight average molecular weight (Mw) 700,000, Hydroxyl value 72 mg KOH / g) 3.0 parts by mass, trimethylolpropane-modified tolylene diisocyanate (product name “Coronate L” manufactured by Nippon Polyurethane Co., Ltd.) as an isocyanate-based crosslinking agent (C), silane 3-Glycidoxypropyl trimer as a coupling agent A pressure-sensitive adhesive composition having a solid content concentration of 40% by mass is mixed with 0.25 part by mass of xylsilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name “KBM-403”), sufficiently stirred and diluted with methyl ethyl ketone. A coating solution was obtained.

Here, Table 1 shows each formulation (solid content converted value) of the adhesive composition when the (meth) acrylic acid ester polymer (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 acid ester polymer (A)]
2EHA: 2-ethylhexyl acrylate IBXA: isobornyl acrylate ACMO: 4-acryloylmorpholine HEA: 2-hydroxyethyl acrylate BA: n-butyl acrylate MMA: methyl methacrylate CHA: cyclohexyl acrylate MA: methyl acrylate
[Isocyanate-based crosslinking agent (C)]
TDI: Trimethylolpropane-modified tolylene diisocyanate (product name “Coronate L” manufactured by Nippon Polyurethane Co., Ltd.)
XDI: trimethylolpropane-modified xylylene diisocyanate (manufactured by Soken Chemical Co., Ltd., product name “TD-75”)

3. Manufacture of an adhesive sheet The coating solution of the adhesive composition obtained by the said process 2 is the heavy peeling type release sheet (product name "SP-PET752150 by the Lintec company) which peeled one side of the polyethylene terephthalate film with the silicone type release agent. It applied | coated with the knife coater to the peeling process surface of "). 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 the conditions of 23 ° C. and 50% RH. A first pressure-sensitive adhesive sheet having a structure of layer (thickness: 25 μm) / light release type release sheet was produced.

  Moreover, the heavy peeling type peeling sheet (product name "SP-PET752150" by the Lintec company) which peeled one side of the polyethylene terephthalate film with the silicone type release agent from the coating solution of the adhesive composition obtained at the said process 2 After coating with a knife coater on the peel-treated surface, a coating layer (thickness: 25 μm) was formed by heat treatment at 90 ° C. for 1 minute. Similarly, the light release release sheet (product name “SP-PET 382120”, manufactured by Lintec Co., Ltd.) obtained by removing one surface of the polyethylene terephthalate film with a silicone-based release agent from the coating solution of the adhesive composition obtained in Step 2 above. ) Was applied with a knife coater, followed by heat treatment at 90 ° C. for 1 minute to form a coating layer (thickness: 25 μm).

  Subsequently, the heavy release type release sheet with the coating layer obtained above and the light release type release sheet with the coating layer obtained above were bonded so that both coating layers were in contact with each other. Then, by curing for 7 days under the condition of 50% RH, a second pressure-sensitive adhesive sheet having a structure of heavy release type release sheet / pressure-sensitive adhesive layer (thickness: 50 μm) / light release type release sheet was produced.

  In addition, the thickness of the said adhesive layer is the value measured using the constant pressure thickness measuring device (The product name "PG-02" by the Teclock company) based on JISK7130.

[Examples 2 to 15, Comparative Examples 1 to 5]
Kind and ratio of each monomer constituting (meth) acrylate polymer (A), weight average molecular weight of (meth) acrylate polymer (A), blending amount of polyrotaxane compound (B), isocyanate-based crosslinking agent A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the type and amount of (C) and the amount of the silane coupling agent were changed as shown in Table 1.

Here, the above-mentioned weight average molecular weight (Mw) is a polystyrene-reduced weight average molecular weight measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).
<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 gel fraction)
The first pressure-sensitive adhesive sheet (thickness of the pressure-sensitive adhesive layer: 25 μm) obtained in Examples and Comparative Examples was cut into a size of 80 mm × 80 mm, and the pressure-sensitive adhesive layer was wrapped in a polyester mesh (mesh size 200). The mass of the pressure-sensitive adhesive alone was calculated by weighing the mass with a precision balance and subtracting the mass of the mesh alone. 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 24 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. The results are shown in Table 2.

[Test Example 2] (Measurement of haze value)
About the adhesive layer of the 1st adhesive sheet (thickness of an adhesive layer: 25 micrometers) obtained by the Example and the comparative example, according to JISK7136: 2000, a haze meter (Nippon Denshoku Industries Co., Ltd. make, product name) The haze value (%) was measured using “NDH-2000”). The results are shown in Table 2.

[Test Example 3] (Tensile test)
A plurality of pressure-sensitive adhesive layers of the second pressure-sensitive adhesive sheets (pressure-sensitive adhesive layer thickness: 50 μm) obtained in Examples and Comparative Examples were laminated to obtain a total thickness of 600 μm, and then a 10 mm wide × 75 mm long sample was prepared. Cut out. The sample is set in a tensile tester (product name “Tensilon”, manufactured by Orientec Co., Ltd.) so that the sample measurement site is 10 mm wide × 20 mm long (extension direction), and the measurement is performed in an environment of 23 ° C. and 50% RH. Using a tensile tester, the film was stretched at a tensile speed of 200 mm / min, and the stress value at which the elongation was 1000% was measured as 1000% modulus (MPa). In addition, when it broke before elongation rate became 1000%, the stress value at the time of the fracture was measured (modulus at the time of fracture). The results are shown in Table 2 (in Table 2, the ones in brackets are the modulus at break).

  In the above tensile test, the sample was stretched until it was broken, and the elongation when the sample was broken, that is, the breaking elongation (%) was measured. The results are shown in Table 2.

[Test Example 4] (Measurement of adhesive strength)
The light release release sheet was peeled from the first pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer thickness: 25 μm) obtained in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was replaced with polyethylene terephthalate (PET ) The film (Toyobo Co., Ltd., product name “PET A4300”, thickness: 100 μm) was bonded to an easy adhesion layer to obtain a laminate of release sheet / adhesive layer / PET film. The obtained laminate was cut into a width of 25 mm and a length of 100 mm, and this was used as a sample.

  In an environment of 23 ° C. and 50% RH, the heavy release type release sheet is peeled off from the above sample, and the exposed adhesive layer is attached to soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd.). And pressurized at 0.5 MPa and 50 ° C. for 20 minutes. Then, after being allowed to stand for 24 hours under the conditions of 23 ° C. and 50% RH, using a tensile tester (Orientec, Tensilon), the adhesive strength (N / 25 mm). Conditions other than those described here were measured according to JIS Z 0237: 2009. The results are shown in Table 2.

[Test Example 5] (Measurement of wet heat adhesion)
For the sample obtained in the same manner as in Test Example 4, the heavy release type release sheet was peeled from the pressure-sensitive adhesive layer in an environment of 23 ° C. and 50% RH, and the exposed pressure-sensitive adhesive layer was treated with soda lime glass (Nippon Sheet Glass Co., Ltd.). After being attached to the product, it was pressurized with an autoclave manufactured by Kurihara Seisakusho at 0.5 MPa and 50 ° C. for 20 minutes. Thereafter, the sample is left for 24 hours under conditions of 60 ° C. and 90% RH, and then left for 24 hours under conditions of normal pressure, 23 ° C. and 50% RH, and then a tensile tester (Orientec Co., Ltd., Tensilon) is used. Used, the adhesive strength (N / 25 mm) was measured under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 degrees. Conditions other than those described here were measured according to JIS Z 0237: 2009. The results are shown in Table 2.

[Test Example 6] (Measurement of step following rate)
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 5 μm, 10 μm, 15 μm, 20 μm and 25 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 5 μm, 10 μm, 15 μm, 20 μm, and 25 μm) was produced.

  The lightly peelable release sheet was peeled off from the second pressure-sensitive adhesive sheet (thickness of the pressure-sensitive adhesive layer: 50 μm) obtained in Examples and Comparative Examples, and the exposed pressure-sensitive adhesive layer was replaced with a polyethylene terephthalate film (Toyobo Co., Ltd.) having an easy-adhesive layer. The product was bonded to an easy-adhesion layer having a product name “PET A4300” (thickness: 100 μm). Next, the heavy release type release sheet was peeled off to expose the pressure-sensitive adhesive layer. Then, using a laminator (product name “LPD3214”, manufactured by Fuji Plastics Co., Ltd.), the laminate is laminated on each stepped glass plate so that the adhesive layer covers the entire frame-like print, and this is used as an evaluation sample. did.

The obtained sample for evaluation was autoclaved for 30 minutes under the conditions of 50 ° C. and 0.5 MPa, and then allowed to stand at normal pressure, 23 ° C. and 50% RH for 24 hours. Subsequently, it was stored for 72 hours under a high-temperature and high-humidity condition of 85 ° C. and 85% RH (endurance test), and then the step following ability was evaluated. Step followability is determined by whether or not the printing step is completely filled with the adhesive layer.If air bubbles, floating, peeling, etc. are observed at the interface between the printing step and the adhesive layer, It is judged that it was not able to follow. Here, the step following property was evaluated as a step following rate (%) represented by the following formula. The results are shown in Table 2.
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 7] (Evaluation of cut suitability)
A plurality of pressure-sensitive adhesive layers of the second pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer thickness: 50 μm) obtained in Examples and Comparative Examples were laminated to obtain a laminate having a total thickness of 1 mm. The laminate was cut with a cutting device (manufactured by Hadano Seisakusho, product name “Super Cutter PN1-600”). The cut surface (length: 100 mm) of the pressure-sensitive adhesive layer after cutting was visually confirmed, and cut suitability was evaluated according to the following criteria. The results are shown in Table 2.
○: No cut of adhesive layer on cut surface Δ: Some cut of adhesive layer on cut surface (less than 10% of cut surface)
×: Adhesive layer chipped on the cut surface (more than 10% of the cut surface)

  As can be seen from Table 2, the pressure-sensitive adhesive sheets obtained in the examples were excellent in step following ability and had good cut suitability, that is, high film strength.

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

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

Claims (2)

At least one display member constituting member having a step on the surface to be bonded;
Other display body components,
A display body comprising an adhesive layer that bonds the one display body constituent member and the other display body constituent member together,
The elongation at break when a tensile test is performed at 23 ° C. for the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is 500% or more,
When a tensile test is performed at 23 ° C. on the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive layer, the pressure-sensitive modulus at break is 0. 22 MPa or more,
Step tracking rate of the adhesive layer state, and are 30% or more,
The step following rate refers to an evaluation sample obtained by laminating one side of the pressure-sensitive adhesive layer on a stepped surface of a stepped glass plate, and autoclaved for 30 minutes at 50 ° C. and 0.5 MPa. Thereafter, after being left for 24 hours under conditions of normal pressure, 23 ° C. and relative humidity of 50%, and subsequently subjected to a durability test for 72 hours under conditions of 85 ° C. and relative humidity of 85%, it is calculated from the following formula. Is a thing
Step follow-up rate (%) = {(height of the step where the embedded state is maintained without bubbles, floating and peeling after the durability test (μm)) / (thickness of the adhesive layer: 50 μm)} × 100
A display body characterized by that. The haze value of the pressure-sensitive adhesive layer, the display body according to claim 1, characterized in that 5% or less.

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