JP2020083924A - Adhesive composition, adhesive, adhesive sheet, constituent body, and method of manufacturing the same - Google Patents

Abstract

To provide an adhesive composition, an adhesive, an adhesive sheet, and a constituent body excellent in step followability and wet heat whitening resistance, and to provide a method of manufacturing the constituent body.SOLUTION: The adhesive composition contains an adhesive main agent and an active energy ray-curable component. The adhesive main agent has a glass transition temperature (Tg) of -25°C or lower. As the active energy ray-curable component, a bifunctional or trifunctional (meth)acrylate having a polyalkylene glycol skeleton is contained.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to an adhesive composition, an adhesive, an adhesive sheet, a constituent suitable for constituting a display (display), and a method for producing the same.

2. Description of the Related Art In recent years, for example, liquid crystal elements, light emitting diodes (LED elements), organic electroluminescence, etc. are used for various instruments such as instrument panels of automobiles, car navigation systems, consoles, and various mobile electronic devices such as smartphones and tablet terminals. A display body using a display module having an (organic EL) element or the like is provided.

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

However, the presence of the above-mentioned void, that is, the air layer, causes a large reflection loss of light due to the difference in the refractive index between the protective panel and the air layer and the difference in the refractive index between the air layer and the display module, and 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-shaped printing 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, which causes reflection loss of light. Therefore, the pressure-sensitive adhesive layer is required to have step followability.

Further, in the conventional pressure-sensitive adhesive layer, there is a problem that the pressure-sensitive adhesive layer may be whitened when it is returned to room temperature and normal humidity after being subjected to high temperature and high humidity (wet heat) conditions. Therefore, the adhesive layer is also required to have resistance to moist heat and whitening.

In order to solve the above-mentioned problem, Patent Document 1 discloses that a monomer component containing a hydroxyl group-containing monomer, a nitrogen atom-containing monomer, an alicyclic structure-containing monomer and an alkyl (meth)acrylate in the presence of an ethylene oxide group-containing dicyano compound. Disclosed is a pressure-sensitive adhesive for a touch panel, which contains a (meth)acrylic polymer obtained by polymerization and a crosslinking agent.

JP, 2016-44293, A

However, the pressure-sensitive adhesive disclosed in Patent Document 1 does not always have sufficient performance in step followability and the like. In particular, a vehicle-mounted display is required to have higher performance because it is placed in a severe environment.

The present invention has been made in view of the above circumstances, and provides a pressure-sensitive adhesive composition excellent in step-following property and resistance to moist heat and whitening, a pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, a structure and a method for producing the same. With the goal.

In order to achieve the above object, firstly, the present invention is a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive main agent and an active energy ray-curable component, wherein the glass transition temperature (Tg) of the pressure-sensitive adhesive main agent is − A tacky composition having a temperature of 25° C. or lower and containing a bifunctional or trifunctional (meth)acrylate having a polyalkylene glycol skeleton as the active energy ray-curable component (Invention 1). ..

According to the above invention (Invention 1), the obtained pressure-sensitive adhesive is excellent in step followability and wet heat whitening resistance.

In the said invention (invention 1), content of the bifunctional or trifunctional (meth)acrylate which has the said polyalkylene glycol skeleton in the said adhesive composition (The bifunctional (meth)acrylate which has a polyalkylene glycol skeleton. And a trifunctional (meth)acrylate having a polyalkylene glycol skeleton, the total content thereof is 2 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the adhesive base agent. Is preferred (Invention 2).

In the said invention (invention 1 and 2), it is preferable that the said adhesive main agent is (meth)acrylic acid ester polymer (A) (invention 3).

In the said invention (invention 3), it is preferable to contain a crosslinking agent (B) (invention 4).

In the above inventions (Inventions 3 and 4), as the active energy ray-curable component, a bifunctional (meth)acrylate (C1) having a polyalkylene glycol skeleton and a trifunctional or more polyfunctional compound having no polyalkylene glycol skeleton ( It is preferable to contain (meth)acrylate (C2) (Invention 5).

In the said invention (invention 5), content of the said (meth)acrylate (C1) in the said adhesive composition is 2 mass with respect to 100 mass parts of the said (meth)acrylic acid ester polymer (A). The content of the (meth)acrylate (C2) in the pressure-sensitive adhesive composition is 1 part by mass or more and 15 parts by mass or less, relative to 100 parts by mass of the (meth)acrylic acid ester polymer (A). It is preferably not less than 15 parts by mass and not more than 15 parts by mass (Invention 6).

In the above inventions (Inventions 5 and 6), the mass ratio of the content of the (meth)acrylate (C1) and the content of the (meth)acrylate (C2) in the adhesive composition is 1:0. It is preferably 0.01 to 1:5 (Invention 7).

Secondly, the present invention provides an active energy ray-curable pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition (Invention 3 to 7) (Invention 8).

Thirdly, the present invention is a pressure-sensitive adhesive sheet comprising at least a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is obtained by curing the active energy ray obtained from the pressure-sensitive adhesive composition (Inventions 1 to 7). Provided is a pressure-sensitive adhesive sheet, which is an adhesive agent of the invention (Invention 9).

In the said invention (invention 9), it is preferable that the gel fraction of the said adhesive is 30% or more and 80% or less (invention 10).

In the above inventions (Inventions 9 and 10), it is preferable to include two release sheets and the pressure-sensitive adhesive layer sandwiched between the release sheets so as to come into contact with the release surfaces of the two release sheets (Invention). 11).

Fourthly, the present invention provides one display member constituting member, another display member constituting member, and a post-curing pressure-sensitive adhesive layer for bonding the one display member constituting member and the other display member constituting member to each other. And the pressure-sensitive adhesive layer after curing is an active energy ray cured product of the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet (Inventions 9 to 11). Invention 12).

In the above invention (Invention 12), it is preferable that at least one of the one display member constituting member and the other display member constituting member has a step at least on the surface on the pressure-sensitive adhesive layer side after curing (Invention 13). ..

In the above inventions (Inventions 12 and 13), it is preferable that the gel fraction of the pressure-sensitive adhesive after curing constituting the pressure-sensitive adhesive layer after curing is 50% or more and 95% or less (Invention 14).

Fifthly, the present invention produces a laminate obtained by laminating one display member constituting member and another display member constituting member via the adhesive layer of the adhesive sheet (Inventions 9 to 11), Provided is a method for producing a structure, which comprises irradiating the pressure-sensitive adhesive layer of the laminate with an active energy ray to cure the pressure-sensitive adhesive layer to obtain a cured pressure-sensitive adhesive layer (Invention 15). ..

The pressure-sensitive adhesive composition, pressure-sensitive adhesive, pressure-sensitive adhesive sheet and composition according to the present invention are excellent in step followability and resistance to moist heat and whitening. Further, according to the method for manufacturing a structure according to the present invention, it is possible to manufacture a structure excellent in step followability and resistance to moist heat and whitening.

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

Hereinafter, embodiments of the present invention will be described.
[Adhesive composition]
The pressure-sensitive adhesive composition according to the present embodiment contains a pressure-sensitive adhesive main agent and an active energy ray-curable component, and the glass transition temperature (Tg) of the pressure-sensitive adhesive main agent is -25°C or lower. Further, the adhesive composition according to the present embodiment contains, as the active energy ray-curable component, a bifunctional or trifunctional (meth)acrylate having a polyalkylene glycol skeleton. The glass transition temperature (Tg) of the adhesive main agent is calculated by the FOX equation based on the glass transition temperature (Tg) as a homopolymer of each monomer constituting the polymer which is the adhesive main agent.

When the pressure-sensitive adhesive composition according to this embodiment has the above-mentioned constitution, the pressure-sensitive adhesive obtained is excellent in step followability and resistance to moist heat and whitening.

Specifically, when the glass transition temperature (Tg) of the adhesive main agent in the adhesive composition according to the present embodiment is -25°C or lower, the obtained adhesive has high flexibility. In addition, the pressure-sensitive adhesive is not yet cured because it is before irradiation with the active energy ray, and the above-mentioned flexibility is maintained. As a result, the pressure-sensitive adhesive becomes excellent in step followability, particularly step followability during bonding (initial step followability).

From the above viewpoint, the glass transition temperature (Tg) of the adhesive main agent is preferably −30° C. or lower, and particularly preferably −35° C. or lower. The lower limit of the glass transition temperature (Tg) is not particularly limited, but from the viewpoint of step followability and blister resistance under high temperature and high humidity conditions, −100° C. or higher is preferable, and −60° C. or higher is particularly preferable, Furthermore, -40 degreeC or more is preferable.

In addition, the bifunctional or trifunctional (meth)acrylate having a polyalkylene glycol skeleton contained in the adhesive composition according to the present embodiment exhibits excellent hydrophilicity and has a skeleton that is flexible even after curing. When such components are present in the pressure-sensitive adhesive, even when the pressure-sensitive adhesive is placed under high-temperature and high-humidity conditions, when the moisture that has penetrated into the pressure-sensitive adhesive under the high-temperature and high-humidity conditions returns to room temperature and normal humidity It is presumed that the adhesive easily comes off, and as a result, whitening of the adhesive is suppressed. Therefore, the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition according to this embodiment is also excellent in wet heat whitening resistance.

Furthermore, the bifunctional or trifunctional (meth)acrylate having the polyalkylene glycol skeleton also acts as a plasticizer, so that the pressure-sensitive adhesive containing the component is more excellent in step followability during bonding. It becomes a thing.

Furthermore, the active energy ray-curable pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition according to the present embodiment, after being adhered to an adherend, is cured by irradiation with active energy rays to give a predetermined hardness and Exhibits adhesive strength. As a result, the step followability under high temperature and high humidity conditions becomes excellent. In addition, the blister resistance is also excellent.

For example, when a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer made of an active energy ray-curable pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition according to the present embodiment is attached to a display member having a step, the pressure-sensitive adhesive layer is It is easy to follow the step, and it is possible to suppress the occurrence of a gap, a float, etc. near the step. Then, after the display member constituting member (for example, a glass plate) having the step and another display member constituting member (for example, a plastic plate) are bonded by the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer is irradiated with active energy rays. After curing, the adhesive layer is obtained after curing. In this way, a constituent body obtained by laminating two indicator constituent members after curing with an adhesive layer is obtained. Even when the structure is placed under a high temperature and high humidity condition, for example, under a condition of 85° C. and 85% RH for 72 hours, bubbles, floating, peeling and the like are suppressed from occurring near the step. Further, the occurrence of blisters such as bubbles, floating, and peeling at the interface between the pressure-sensitive adhesive layer and the display member (particularly the plastic plate) is also suppressed. Furthermore, in the constitutional body taken out under the high temperature and high humidity condition, an increase in haze value, that is, whitening is suppressed.

In the present specification, "step followability" means that when foreign matter is present between the pressure-sensitive adhesive layer and the adherend, occurrence of bubbles, floating, peeling, etc. around the foreign matter is suppressed. The concept of foreign matter embedding property is also included.

The type of adhesive main agent in the adhesive composition according to the present embodiment may be any of acrylic, polyester, polyurethane, rubber, silicone and the like, but in view of step followability and resistance to moist heat and whitening. Therefore, acrylic is preferable. That is, specifically, the adhesive main agent in the adhesive composition according to the present embodiment is preferably the (meth)acrylic acid ester polymer (A). Therefore, the pressure-sensitive adhesive composition according to the present embodiment (hereinafter, also referred to as “pressure-sensitive adhesive composition P”) has a (meth)acrylic acid ester polymer (A) and a bifunctional compound having a polyalkylene glycol skeleton or It is preferable to contain the active energy ray-curable component (C) containing a trifunctional (meth)acrylate, and it is preferable to further contain a crosslinking agent (B). In addition, the adhesive composition P includes a bifunctional (meth)acrylate (C1) having a polyalkylene glycol skeleton as an active energy ray-curable component (C), and a trifunctional or more polyfunctional compound having no polyalkylene glycol skeleton ( It is particularly preferable to contain (meth)acrylate (C2).

1. Constituent component (1) (meth)acrylic acid ester polymer (A)
The (meth)acrylic acid ester polymer (A) preferably contains a reactive functional group-containing monomer having a reactive functional group in the molecule as a monomer constituting the polymer. By containing this reactive functional group-containing monomer, it reacts with the crosslinking agent (B) described later through the reactive functional group derived from the reactive functional group-containing monomer, and thereby the crosslinked structure (three-dimensional network structure) ) Is formed, and a pressure-sensitive adhesive having a predetermined cohesive force is obtained.

Examples of the reactive functional group-containing monomer contained in the (meth)acrylic acid ester polymer (A) as a monomer unit constituting the polymer include a monomer having a hydroxyl group in the molecule (a hydroxyl group-containing monomer) and a carboxy group in the molecule. Preferable examples thereof include a monomer having a group (carboxy group-containing monomer) and a monomer having an amino group in the molecule (amino group-containing monomer). These reactive functional group-containing monomers may be used alone or in combination of two or more.

Among the above reactive functional group-containing monomers, a hydroxyl group-containing monomer and a carboxy group-containing monomer are preferable, and a hydroxyl group-containing monomer is particularly preferable from the viewpoint of glass transition temperature (Tg).

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and (meth ) Examples include hydroxyalkyl esters of (meth)acrylic acid such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth)acrylate. Among them, 2-hydroxyethyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate is preferable from the viewpoint of reactivity with a crosslinking agent and glass transition temperature (Tg), and 2-hydroxyethyl acrylate or acrylic is particularly preferable. The 4-hydroxybutyl acid is preferred. These may be used alone or in combination of two or more.

The (meth)acrylic acid ester polymer (A) preferably contains a reactive functional group-containing monomer as a monomer unit constituting the polymer at a lower limit of 5% by mass or more, and particularly at least 8% by mass. It is preferable that the content is 12% by mass or more. In particular, the (meth)acrylic acid ester polymer (A) preferably contains a hydroxyl group-containing monomer in the above amount as a monomer unit constituting the polymer. As a result, the pressure-sensitive adhesive sheet 1 is excellent in step followability under high temperature and high humidity conditions and resistance to moist heat and whitening, and has good compatibility with the active energy ray-curable component (C). The property is improved.

In addition, the (meth)acrylic acid ester polymer (A) preferably contains a reactive functional group-containing monomer as a monomer unit constituting the polymer in an amount of 35% by mass or less as an upper limit, and particularly 24% by mass. It is preferable to contain the following. Thereby, it becomes possible to sufficiently secure the content of the monomer other than the reactive functional group-containing monomer, and the adhesiveness of the obtained pressure-sensitive adhesive becomes more excellent. Further, from the viewpoint that the glass transition temperature (Tg) of the (meth)acrylic acid ester polymer (A) can be adjusted to a suitable value, it is more preferable that the reactive functional group-containing monomer is contained in an amount of 20% by mass or less, and 18 Most preferably, the content is at most mass %. As a result, the obtained pressure-sensitive adhesive sheet is excellent in initial step followability and step followability under high temperature and high humidity conditions.

It is also preferable that the (meth)acrylic acid ester polymer (A) 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 the carboxy group-containing monomer, the object to which the pressure-sensitive adhesive is attached causes a problem due to the acid, for example, a transparent conductive film such as tin-doped indium oxide (ITO) or a metal film, Even when a metal mesh or the like is present, it is possible to suppress the defects (corrosion, resistance value change, etc.) due to the acid.

Here, "does not contain a carboxy group-containing monomer" means that it does not substantially contain a carboxy group-containing monomer, and does not contain a carboxy group-containing monomer at all, or a transparent conductive film or metal wiring by a carboxy group, etc. The carboxy group-containing monomer is allowed to be contained to such an extent that the above-mentioned corrosion does not occur. Specifically, in the (meth)acrylic acid ester polymer (A), as a monomer unit, a carboxy group-containing monomer is 0.1% by mass or less, preferably 0.01% by mass or less, and more preferably 0.001%. It is allowed to be contained in an amount of not more than mass %.

The (meth)acrylic acid ester polymer (A) preferably contains a (meth)acrylic acid alkyl ester as a monomer unit constituting the polymer. Thereby, good adhesiveness can be exhibited. The alkyl group may be linear or branched.

As the (meth)acrylic acid alkyl ester, a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms is preferable from the viewpoint of adhesiveness. Examples of the (meth)acrylic acid alkyl ester whose alkyl group has 1 to 20 carbon atoms 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 the above, (meth)acrylic acid alkyl ester having 2 to 12 carbon atoms of the alkyl group is more preferable, and alkyl ester of acrylic acid having 5 to 10 carbon atoms of the alkyl group is more preferable from the viewpoint of efficiently imparting adhesive force. Is particularly preferable. Specifically, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate and isooctyl (meth)acrylate are preferable, 2-ethylhexyl acrylate and isooctyl acrylate are more preferable, and glass transition temperature is preferable. From the viewpoint of (Tg), 2-ethylhexyl acrylate is particularly preferable. These may be used alone or in combination of two or more.

From the viewpoint of imparting tackiness, the (meth)acrylic acid ester polymer (A) has 40 (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms as a monomer unit constituting the polymer. The content is preferably at least mass%, more preferably at least 50 mass%, further preferably at least 55 mass%. Further, from the viewpoint of ensuring the blending amount of other components, it is preferable to contain 90% by mass or less, and 85% by mass or less of a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms. More preferably, it is particularly preferably contained in an amount of 75% by mass or less, further preferably 65% by mass or less.

Moreover, it is preferable that the (meth)acrylic acid ester polymer (A) contains a monomer having an alicyclic structure (alicyclic structure-containing monomer) as a monomer unit constituting the polymer. By containing the alicyclic structure-containing monomer, the bulky functional group expands the distance between the (meth)acrylic acid ester polymers (A) to further increase the flexibility of the pressure-sensitive adhesive before curing with active energy rays. It is easy, and thereby it is possible to further improve the step followability during bonding (initial step followability). Further, it is easy to exhibit flexibility even in the pressure-sensitive adhesive after curing with active energy rays (hereinafter sometimes referred to as “cured pressure-sensitive adhesive”), and to improve step followability under high temperature and high humidity conditions. You can Further, due to the above-mentioned flexibility, the conformability to the interface of the adherend is also excellent, so that the generation of bubbles is suppressed and the blister resistance is also excellent.

The carbon ring having an alicyclic structure may have a saturated structure or may have an unsaturated bond. Further, the alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as a bicyclic ring or a tricyclic ring. The alicyclic structure preferably has 5 to 20 carbon atoms, particularly preferably 6 to 15 carbon atoms, and further preferably 7 to 12 carbon atoms.

Examples of the alicyclic structure include cyclohexyl skeleton, dicyclopentadiene skeleton, adamantane skeleton, isobornyl skeleton, cycloalkane skeleton (cycloheptane skeleton, cyclooctane skeleton, cyclononane skeleton, cyclodecane skeleton, cycloundecane skeleton, etc.) Preferred examples include those containing a cycloalkene skeleton (cycloheptene skeleton, cyclooctene skeleton, etc.), norbornene skeleton, norbornadiene skeleton, polycyclic skeleton (cuban skeleton, basket skeleton, hausan skeleton, etc.), and spiro skeleton. Among them, those containing an adamantane skeleton and an isobornyl skeleton are preferable from the viewpoint of further enhancing the step followability.

The alicyclic structure-containing monomer is preferably a (meth)acrylic acid ester monomer containing the skeleton, and specifically, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, (meth) Examples thereof include adamantyl acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, and dicyclopentenyloxyethyl (meth)acrylate. Among them, adamantyl (meth)acrylate and isobornyl (meth)acrylate. Is preferred, and isobornyl acrylate is particularly preferred. These may be used alone or in combination of two or more.

The (meth)acrylic acid ester polymer (A) contains 3% by mass or more of an alicyclic structure-containing monomer as a monomer unit constituting the polymer, from the viewpoint of further increasing the flexibility of the obtained pressure-sensitive adhesive after curing. It is preferably contained, more preferably 8% by mass or more, particularly preferably 12% by mass or more.

In addition, the content of the alicyclic structure-containing monomer in the (meth)acrylic acid ester polymer (A) is preferably 30% by mass or less, and 22% by mass, from the viewpoint of ensuring the blending amount of other components. It is more preferable that the amount is not more than 18% by mass, and particularly preferably 18% by mass or less.

Moreover, it is preferable that the (meth)acrylic acid ester polymer (A) contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer. By containing the nitrogen atom-containing monomer, the adhesion to the adherend such as glass can be improved. 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 heterocycle, and the like, and among them, a monomer having a nitrogen-containing heterocycle is preferable. Further, from the viewpoint of increasing the degree of freedom of the nitrogen atom-containing monomer-derived portion in the higher-order structure of the constituted adhesive, the nitrogen atom-containing monomer forms the (meth)acrylic acid ester polymer (A). It is preferred that no reactive unsaturated double bond group be contained other than the one polymerizable group used for the polymerization of.

Examples of the monomer having a nitrogen-containing heterocycle 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, which exhibits more excellent adhesive strength, is preferable, and N-acryloylmorpholine is particularly preferable.

As the nitrogen atom-containing monomer, for example, (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-vinyl Caprolactam, monomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, monoethylaminopropyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, etc. It can also be used.
The above nitrogen atom-containing monomers may be used alone or in combination of two or more.

The (meth)acrylic acid ester polymer (A) contains 1% by mass or more of a nitrogen atom-containing monomer as a monomer unit constituting the polymer from the viewpoint of improving adhesion to an adherend such as glass. It is preferable that the content is 4% by mass or more, more preferably 8% by mass or more. Further, the content of the nitrogen atom-containing monomer is preferably 20% by mass or less, more preferably 15% by mass or less, and 12% by mass or less from the viewpoint of securing the blending amount of the other components. Is particularly preferable.

The (meth)acrylic acid ester polymer (A) is preferably a solution polymerized product obtained by a solution polymerization method. Since it is a solution polymer, a high molecular weight polymer can be easily obtained, and a pressure-sensitive adhesive excellent in step followability under high temperature and high humidity conditions can be obtained.

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

The lower limit of the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably 200,000 or more, particularly preferably 300,000 or more, and further preferably 400,000 or more. When the lower limit of the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is above, the resulting pressure-sensitive adhesive will have more excellent step followability under high temperature and high humidity conditions.

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 850,000 or less, and further preferably 800,000 or less. preferable. When the upper limit of the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is the above, the initial step followability of the obtained pressure-sensitive adhesive becomes 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 addition, in the adhesive composition P, the (meth)acrylic acid ester polymer (A) may be used alone or in combination of two or more kinds.

The content of the (meth)acrylic acid ester polymer (A) in the adhesive composition P according to the present embodiment is preferably 70% by mass or more, particularly preferably 75% by mass or more, and Is preferably 80% by mass or more. Further, the content of the (meth)acrylic acid ester polymer (A) is preferably 99% by mass or less, particularly preferably 97% by mass or less, and further preferably 95% by mass or less. .. Since the content of the (meth)acrylic acid ester polymer (A) is in the above range, the content of the active energy ray-curable component (C) is also in a suitable range, and the step followability and the resistance to moist heat and whitening are more improved. It will be excellent.

(2) Crosslinking agent (B)
The crosslinking agent (B) can crosslink the (meth)acrylic acid ester polymer (A) by heating the pressure-sensitive adhesive composition P, and can favorably form a crosslinked structure having a three-dimensional network structure. As a result, a pressure-sensitive adhesive having a predetermined cohesive force is obtained, and the step followability and the blister resistance under high temperature and high humidity conditions are further improved.

The cross-linking agent (B) may be any as long as it reacts with the reactive functional group of the (meth)acrylic acid ester polymer (A), and examples thereof include an isocyanate cross-linking agent, an epoxy cross-linking agent, and an amine cross-linking agent. Agent, melamine-based crosslinking agent, aziridine-based crosslinking agent, hydrazine-based crosslinking agent, aldehyde-based crosslinking agent, oxazoline-based crosslinking agent, metal alkoxide-based crosslinking agent, metal chelate-based crosslinking agent, metal salt-based crosslinking agent, ammonium salt-based crosslinking agent Etc. Here, when the (meth)acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer as a constituent monomer unit, the crosslinking agent (B) is an isocyanate type crosslinking agent excellent in reactivity with a hydroxyl group. Preference is given to using. The crosslinking agent (B) may be used alone or in combination of two or more.

The isocyanate cross-linking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic diisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate, and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, and alicyclic polyisocyanates such as hydrogenated diphenylmethane diisocyanate. And their biurets, isocyanurates, and adducts which are reaction products with low molecular weight active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane and castor oil. Among them, trimethylolpropane-modified aromatic polyisocyanate, particularly trimethylolpropane-modified tolylene diisocyanate and trimethylolpropane-modified xylylene diisocyanate are preferable from the viewpoint of reactivity with a hydroxyl group.

The content of the cross-linking agent (B) in the adhesive composition P is preferably 0.01 parts by mass or more, and particularly preferably 0.1 part by mass, relative to 100 parts by mass of the (meth)acrylic acid ester polymer (A). The amount is preferably 05 parts by mass or more, and more preferably 0.1 parts by mass or more. Further, the content is preferably 1.0 part by mass or less, particularly preferably 0.8 part by mass or less, and further preferably 0.5 part by mass or less. When the content of the cross-linking agent (B) is the above, a predetermined cross-linking structure is formed, and the resulting pressure-sensitive adhesive becomes more excellent in step followability under high temperature and high humidity conditions.

(3) Active energy ray curable component (C)
The adhesive composition P in the present embodiment contains an active energy ray-curable component (C) containing a bifunctional or trifunctional (meth)acrylate having a polyalkylene glycol skeleton. In the pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition P, the active energy ray-curable component (C) remains unreacted. When the pressure-sensitive adhesive is irradiated with active energy rays, the active energy ray-curable component (C) in the pressure-sensitive adhesive is polymerized by cleavage of the unsaturated double bond, whereby the pressure-sensitive adhesive is cured.

The adhesive composition P in the present embodiment may contain only a bifunctional (meth)acrylate having a polyalkylene glycol skeleton as the active energy ray-curable component (C), or has a polyalkylene glycol skeleton. It may contain only a trifunctional (meth)acrylate, or may contain a bifunctional (meth)acrylate having a polyalkylene glycol skeleton and a trifunctional (meth)acrylate having a polyalkylene glycol skeleton. It is good to contain a bifunctional (meth)acrylate having a polyalkylene glycol skeleton and/or a trifunctional (meth)acrylate having a polyalkylene glycol skeleton and a (meth)acrylate not having a polyalkylene glycol skeleton. Good. The (meth)acrylate not having a polyalkylene glycol skeleton may be monofunctional, bifunctional, or trifunctional or more. Among the above forms, it is particularly preferable to contain a bifunctional (meth)acrylate (C1) having a polyalkylene glycol skeleton and a trifunctional or higher functional (meth)acrylate (C2) having no polyalkylene glycol skeleton.

As the active energy ray-curable component (C), a bifunctional (meth)acrylate (C1) having a polyalkylene glycol skeleton and a trifunctional or higher functional (meth)acrylate (C2) having no polyalkylene glycol skeleton are contained. When an active energy ray is irradiated to the pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition P, the C1 components and the C2 components are polymerized, or the C1 component and the C2 component are polymerized.

When the bifunctional (meth)acrylate (C1) having a polyalkylene glycol skeleton and the trifunctional or higher functional (meth)acrylate (C2) having no polyalkylene glycol skeleton are contained, the pressure-sensitive adhesive after curing is contained. Is a structure that exhibits flexibility derived from a bifunctional (meth)acrylate (C1) having a polyalkylene glycol skeleton, and a relatively derived trifunctional or higher functional (meth)acrylate (C2) that does not have a polyalkylene glycol skeleton. It has a cross-linking structure having both a rigid structure. As a result, it is possible to obtain a pressure-sensitive adhesive after curing that has both appropriate flexibility and cohesive strength, and to make it possible to further improve step followability under high temperature and high humidity conditions, and further to improve blister resistance. It can be better.

(3-1) (meth)acrylate (C1)
The (meth)acrylate (C1) in the present embodiment is a bifunctional (meth)acrylate having a polyalkylene glycol skeleton. Examples of the polyalkylene glycol having a polyalkylene glycol skeleton include homopolymers such as polyethylene glycol, polypropylene glycol and polytetramethylene glycol, and copolymers such as ethylene glycol-propylene glycol copolymers. Among these, polyethylene glycol is preferable from the viewpoint of resistance to moist heat and whitening.

The weight average molecular weight of the polyalkylene glycol skeleton is preferably 100 or more, particularly preferably 150 or more, and further preferably 200 or more. The weight average molecular weight of the polyalkylene glycol skeleton is preferably 5,000 or less, particularly preferably 4,000 or less, and further preferably 3,000 or less, from the viewpoint of the optical characteristics of the obtained pressure-sensitive adhesive. It is preferably less than 1000, particularly preferably 800 or less, and most preferably 500 or less. When the weight average molecular weight of the polyalkylene glycol skeleton is in the above range, the wet heat whitening resistance and the step followability become more excellent. Further, the compatibility with other components (particularly the acrylic acid ester copolymer (A)) is excellent, and the optical characteristics (haze value) of the pressure-sensitive adhesive can be improved.

Examples of the (meth)acrylate (C1) include polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, and polyisobutylene glycol (meth)acrylate. Among the above, polyethylene glycol diacrylate or polyethylene glycol dimethacrylate is preferable from the viewpoint of resistance to moist heat and whitening and step followability, and polyethylene glycol dimethacrylate is particularly preferable from the viewpoint of blister resistance. These may be used alone or in combination of two or more.

The content of the (meth)acrylate (C1) (and the trifunctional (meth)acrylate having a polyalkylene glycol skeleton) in the adhesive composition P is 100 parts by mass of the (meth)acrylic acid ester polymer (A). On the other hand, it is preferably 2 parts by mass or more, more preferably 3 parts by mass or more, particularly preferably 5 parts by mass or more, and further preferably 6 parts by mass or more. Further, the above content is preferably 15 parts by mass or less, particularly preferably 12 parts by mass or less, and further preferably 10 parts by mass or less. When the content of the (meth)acrylate (C1) is within the above range, the pressure-sensitive adhesive after curing is more excellent in the resistance to moist heat and whitening and the step followability.

(3-2) (meth)acrylate (C2)
The (meth)acrylate (C2) in the present embodiment is a tri- or higher functional (meth)acrylate having no polyalkylene glycol skeleton. That is, the number of unsaturated double bonds in (meth)acrylate (C2) is 3 or more. The upper limit of the number of unsaturated double bonds is not particularly limited, but it is usually preferably 9 or less, particularly preferably 6 or less, and further preferably 4 or less.

Examples of the (meth)acrylate (C2) include trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, Trifunctional type such as propylene oxide modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, ε-caprolactone modified tris-(2-(meth)acryloxyethyl)isocyanurate; diglycerin tetra(meth) ) Acrylate, tetrafunctional type such as pentaerythritol tetra(meth)acrylate; 5-functional type such as propionic acid-modified dipentaerythritol penta(meth)acrylate; dipentaerythritol hexa(meth)acrylate, caprolactone-modified dipentaerythritol hexa(meth) ) Hexafunctional type such as acrylate and the like. These may be used alone or in combination of two or more. From the viewpoint of compatibility with the (meth)acrylic acid ester polymer (A), the (meth)acrylate (C2) preferably has a molecular weight of less than 1,000.

Among the above, a trifunctional (meth)acrylate is preferable from the viewpoint of the step followability and the blister resistance of the pressure-sensitive adhesive after curing under high temperature and high humidity conditions, and in particular, a trifunctional (meth)acrylate having an isocyanurate structure in the molecule ( (Meth)acrylate is preferred. Specifically, ε-caprolactone-modified tris-(2-(meth)acryloxyethyl) isocyanurate is preferable, and ε-caprolactone-modified tris-(2-acryloxyethyl) isocyanurate is particularly preferable.

The content of the (meth)acrylate (C2) in the adhesive composition P is preferably 1 part by mass or more, and 2 parts by mass with respect to 100 parts by mass of the (meth)acrylic acid ester polymer (A). It is particularly preferable that the amount is 3 parts by mass or more. Further, the above content is preferably 15 parts by mass or less, particularly preferably 10 parts by mass or less, and further preferably 8 parts by mass or less. When the content of the (meth)acrylate (C2) is within the above range, the step followability and the blister resistance of the pressure-sensitive adhesive after curing will be more excellent.

Further, the mass ratio of the content of the (meth)acrylate (C1) to the (meth)acrylate (C2) in the adhesive composition P is preferably 1:0.01 to 1:5, and 1: It is more preferably 0.05 to 1:4, particularly preferably 1:0.1 to 1:3, further preferably 1:0.2 to 1:0.9, and 1 : 0.4 to 1:0.7 is most preferable. When the mass ratio is within the above range, it is possible to further improve the wet heat whitening resistance and the step followability.

Further, the content of the active energy ray-curable component (C) in the adhesive composition P (the total amount of (meth)acrylate (C1) and (meth)acrylate (C2)) is the resistance to moist heat and whitening and the step followability. From the viewpoint of further improving the properties, the lower limit is preferably 1 part by mass or more, and more preferably 5 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic acid ester polymer (A). The amount is more preferably 7 parts by mass or more, particularly preferably 9 parts by mass or more, and most preferably 10 parts by mass or more. On the other hand, the above content is preferably 30 parts by mass or less as an upper limit, and 25 parts by mass or less from the viewpoint of adhesive strength and compatibility with the (meth)acrylic acid ester polymer (A). It is more preferably 20 parts by mass or less, particularly preferably 13 parts by mass or less.

(4) Photopolymerization initiator (D)
When ultraviolet rays are used as the active energy rays used to cure the active energy ray-curable adhesive obtained from the adhesive composition P, the adhesive composition P further contains a photopolymerization initiator (D). It is preferable to contain. By thus containing the photopolymerization initiator (D), the active energy ray-curable component (C) can be efficiently polymerized, and the polymerization and curing time and the irradiation amount of the active energy ray can be reduced. it can.

Examples of such a photopolymerization initiator (D) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 2,2-dimethoxy. 2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexylphenylketone, 2-methyl-1-[4- (Methylthio)phenyl]-2-morpholino-propan-1-one, 4-(2-hydroxyethoxy)phenyl-2-(hydroxy-2-propyl)ketone, benzophenone, p-phenylbenzophenone, 4,4′-diethylamino Benzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2 ,4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoic acid ester, oligo[2-hydroxy-2-methyl-1[4-(1-methylvinyl)phenyl]propanone], 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.

Among the above, the phosphine oxide-based photopolymerization initiator is preferable because it is easy to be cleaved and the adhesive can be surely cured even when irradiated with ultraviolet rays through the plastic plate containing the ultraviolet absorber. Specifically, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide and the like are preferable.

The content of the photopolymerization initiator (D) in the adhesive composition P is preferably 1 part by mass or more, and particularly 3 parts by mass or more based on 100 parts by mass of the active energy ray-curable component (C). And more preferably 6 parts by mass or more. Further, the content of the photopolymerization initiator (D) is preferably 30 parts by mass or less, more preferably 20 parts by mass or less, particularly preferably 10 parts by mass or less, and further 8 parts by mass. It is preferably not more than 7 parts by mass, and most preferably not more than 7 parts by mass.

(5) Silane coupling agent (E)
It is preferable that the adhesive composition P further contains a silane coupling agent (E). Thereby, whether the adherend is a plastic plate or a glass member, the adhesion to the adherend is improved, and the step followability and the blister resistance are further improved.

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 polymer (A), and has high light transmittance. Those having are preferable.

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

The content of the silane coupling agent (E) in the pressure-sensitive adhesive composition P is preferably 0.01 parts by mass or more, particularly preferably 100 parts by mass with respect to 100 parts by mass of the (meth)acrylic acid ester polymer (A). The amount is preferably 0.05 part by mass or more, and more preferably 0.1 part by mass or more. Further, the content is preferably 2 parts by mass or less, particularly preferably 1 part by mass or less, and further preferably 0.5 parts by mass or less.

(6) Various additives In the pressure-sensitive adhesive composition P, if desired, various additives usually used for acrylic pressure-sensitive adhesives, for example, ultraviolet absorbers, antistatic agents, tackifiers, antioxidants, and light stabilizers. Agents, softening agents, fillers, refractive index adjusting agents, rust preventives and the like can be added. In addition, the below-mentioned polymerization solvent and diluent solvent are not included in the additives constituting the adhesive composition P.

2. Production of Adhesive Composition Adhesive composition P was produced by producing (meth)acrylic acid ester polymer (A), and obtained (meth)acrylic acid ester polymer (A) and crosslinking agent (B). , The active energy ray-curable component (C) ((meth)acrylate (C1) and (meth)acrylate (C2)), and, if desired, a photopolymerization initiator (D), a silane coupling agent (E). ) And an additive, and it can manufacture.

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, optionally using a polymerization initiator. However, the present invention is not limited to this, and the polymerization may be performed without a solvent. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like, and 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(cyclohexane1-carbonitrile), and ,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 the organic peroxide include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl)peroxy. Dicarbonate, t-butyl peroxy neodecanoate, t-butyl peroxy vivarate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like can be mentioned.

In the polymerization step, the weight average molecular weight of the obtained polymer can be adjusted by adding a chain transfer agent such as 2-mercaptoethanol.

When the (meth)acrylic acid ester polymer (A) is obtained, a crosslinking agent (B), an active energy ray-curable component (C) ((meth)) is added to a solution of the (meth)acrylic acid ester polymer (A). Acrylate (C1) and (meth)acrylate (C2)), and optionally a photopolymerization initiator (D), a silane coupling agent (E), and an additive are added and sufficiently mixed to dilute the solvent. The adhesive composition P (coating solution) can be obtained. In any of the above components, when a solid one is used, or when precipitation occurs when mixed with other components in an undiluted state, the component alone is preliminarily diluted with a solvent. It may be dissolved or diluted and then mixed with other components.

Examples of the diluent solvent include hexane, heptane, aliphatic hydrocarbons such as cyclohexane, toluene, aromatic hydrocarbons such as xylene, methylene chloride, halogenated hydrocarbons such as 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 is diluted so that the concentration of the adhesive composition P is 10 to 60% by mass. In addition, when obtaining a coating solution, addition of a diluting solvent or the like is not a necessary condition, and a diluting solvent may not be added as long as it has a viscosity such that the adhesive composition P can be coated. 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 diluting solvent.

[Adhesive]
The pressure-sensitive adhesive according to this embodiment is obtained from the pressure-sensitive adhesive composition according to the above-described embodiment, and is preferably obtained by crosslinking (heat-crosslinking) the pressure-sensitive adhesive composition P described above. The (meth)acrylic acid ester polymer (A) in the pressure-sensitive adhesive according to the present embodiment is crosslinked by the crosslinking agent (B) to form a crosslinked structure, while the active energy ray-curable component (C) is used. Exists in the adhesive as it is without being cured. Therefore, the pressure-sensitive adhesive according to the present embodiment is an active energy ray-curable pressure-sensitive adhesive having a property of being cured by irradiation with active energy rays.

Crosslinking of the adhesive composition P can usually be performed by heat treatment. The heat treatment can also be used as a drying treatment when the diluent solvent or the like is volatilized from the coating film of the adhesive composition P applied to a desired object.

The heating temperature of the heat treatment is preferably 50 to 150°C, and particularly preferably 70 to 120°C. Further, the heating time is preferably 10 seconds to 10 minutes, and particularly preferably 50 seconds to 5 minutes.

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

By the above heat treatment (and curing), the (meth)acrylic acid ester polymer (A) is satisfactorily crosslinked through the crosslinking agent (B). The active energy ray-curable component (C) is contained in the pressure-sensitive adhesive without being reacted.

[Adhesive sheet]
The pressure-sensitive adhesive sheet according to one embodiment of the present invention includes at least a pressure-sensitive adhesive layer, and preferably, a release sheet is laminated on one side or both sides of the pressure-sensitive adhesive layer.

The pressure-sensitive adhesive sheet according to the present embodiment is preferably used for laminating one member and another member, in particular, at least one of the one member and the other member is at least on the surface of the pressure-sensitive adhesive layer. It is preferably used in the case of having a step, and further preferably used in the case where at least one member generates outgas under the conditions of high temperature and high humidity and transmits water vapor. The member is preferably a hard body. Further, as the above member, a display member constituting member is preferably cited, and therefore, the pressure-sensitive adhesive sheet according to the present embodiment is preferably used for optical applications, but is not limited to this.

A specific configuration as an example of the pressure-sensitive adhesive sheet according to the present embodiment is shown in FIG.
As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 according to one 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 sandwiched between the active energy ray-curable pressure-sensitive adhesive layers 11. In addition, the release surface of the release sheet in the present specification refers to a surface having releasability in the release sheet, and includes both a release-treated surface and a release-removable surface. ..

1. Each member 1-1. Pressure-sensitive adhesive layer The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer 11 is the pressure-sensitive adhesive according to the above-described embodiment. That is, it is preferably a pressure-sensitive adhesive obtained by cross-linking (thermal cross-linking) the above-mentioned pressure-sensitive adhesive composition P.

The thickness of the pressure-sensitive adhesive layer 11 (value measured according to JIS K7130) is preferably 15 μm or more as a lower limit, more preferably 30 μm or more, and particularly preferably 50 μm or more. Further, the thickness of the pressure-sensitive adhesive layer 11 is preferably 400 μm or less as an upper limit value, more preferably 350 μm or less, particularly preferably 300 μm or less, and further preferably 250 μm or less, Most preferably, it is 100 μm or less. When the thickness of the pressure-sensitive adhesive layer 11 is within the above range, the step followability and the resistance to moist heat and whitening become more excellent.

1-2. Release Sheet The release sheets 12a and 12b protect the active energy ray-curable 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 always necessary.

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, 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. Further, these crosslinked films are also used. Furthermore, these laminated films may be used.

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

The thickness of the release sheets 12a and 12b is not particularly limited, but is usually about 20 to 150 μm.

2. Production of pressure-sensitive adhesive sheet As one production example of the pressure-sensitive adhesive sheet 1, a pressure-sensitive adhesive composition is obtained by applying the coating solution of the pressure-sensitive adhesive composition P to the release surface of one release sheet 12a (or 12b) and performing heat treatment. After P is thermally crosslinked to form a coating layer, the peeling surface of the other release sheet 12b (or 12a) is superposed on the coating layer. When the curing period is necessary, the curing period is set, and when the curing period is not necessary, the coating layer becomes the active energy ray-curable pressure-sensitive adhesive layer 11 as it is. Thereby, the adhesive sheet 1 is obtained. The heat treatment and curing conditions are as described above.

As another production example of the pressure-sensitive adhesive sheet 1, the release surface of one release sheet 12a is coated with the coating solution of the pressure-sensitive adhesive composition P, followed by heat treatment to thermally crosslink the pressure-sensitive adhesive composition P, and then coating. A layer is formed and the release sheet 12a with a coating layer is obtained. In addition, a coating solution of the adhesive composition P is applied to the release surface of the other release sheet 12b, heat treatment is performed to thermally crosslink the adhesive composition P, a coating layer is formed, and a coating layer is provided. To obtain a release sheet 12b. Then, the release sheet 12a with the coating layer and the release sheet 12b with the coating layer are attached to each other so that both coating layers contact each other. When the curing period is required, the curing period is set, and when the curing period is not necessary, the above-mentioned laminated coating layer becomes the active energy ray-curable pressure-sensitive adhesive layer 11. Thereby, the adhesive sheet 1 is obtained. According to this manufacturing example, even if the pressure-sensitive adhesive layer 11 is thick, it is possible to manufacture it stably.

As a method of applying the coating solution of the adhesive composition P, 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.

3. Physical Properties (1) Gel Fraction The gel fraction of the active energy ray-curable pressure-sensitive adhesive (before active energy ray irradiation) constituting the pressure-sensitive adhesive layer 11 is preferably 30% or more as a lower limit, and particularly 35%. It is preferably at least 40%, more preferably at least 40%. When the lower limit of the gel fraction of the pressure-sensitive adhesive is as described above, the pressure-sensitive adhesive has a predetermined cohesive force, and the pressure-sensitive adhesive may adhere to the blade when cutting the pressure-sensitive adhesive sheet 1 or the like, or during storage. It is possible to effectively prevent the pressure sensitive adhesive from seeping out of the pressure sensitive adhesive layer 11. The gel fraction of the pressure-sensitive adhesive is preferably 80% or less as an upper limit value, particularly preferably 70% or less, and further preferably 65% or less. When the upper limit of the gel fraction of the pressure-sensitive adhesive is above, the pressure-sensitive adhesive does not become too hard, and the initial step followability is excellent. Further, the pressure-sensitive adhesive after curing after irradiation with active energy rays does not become too hard, and the step-following property of the pressure-sensitive adhesive layer after curing under high temperature and high humidity conditions becomes more excellent. The method for measuring the gel fraction of the active energy ray-curable pressure-sensitive adhesive is as shown in the test example described later.

The increase in the gel fraction accompanying the curing of the active energy ray-curable pressure-sensitive adhesive by irradiation with active energy rays is preferably 5 points or more, particularly preferably 7 points or more, and further 10 points or more. Preferably. By increasing the gel fraction in this way, the obtained cured pressure-sensitive adhesive layer becomes more excellent in the step followability under high temperature and high humidity conditions. The upper limit of the increase in the gel fraction is not particularly limited, but the increase in the gel fraction is preferably 45 points or less from the viewpoint of preventing the adhesive layer after curing from becoming too hard. In particular, it is preferably 40 points or less, more preferably 35 points or less.

(2) Initial step-following rate Regarding the step-following ability at the time of bonding, the pressure-sensitive adhesive layer 11 preferably has an initial step-following rate (%) represented by the following formula of 30% or more, particularly 40%. % Or more, and more preferably 50% or more. Thereby, it can be said that the step followability at the time of bonding (the initial step followability) is excellent. The upper limit of the initial step follow-up rate is not particularly limited, but is usually preferably 80% or less, and particularly preferably 70% or less.
Initial step follow-up rate (%)={(step height (μm) in which the filled state was maintained without bubbles, floating, peeling, etc.)/(thickness of adhesive layer)}×100
The test method of the initial step follow-up rate is as shown in the test example described later.

(Structure)
A structure according to an embodiment of the present invention is a post-curing adhesive that bonds one display member forming member, another display member forming member, and one display member forming member and another display member forming member to each other. And a composition layer. The structure according to the present embodiment may be one member forming the display or the display itself.

At least one of the one display member forming member and the other display member forming member preferably has a step on at least the surface on the pressure-sensitive adhesive layer side. Further, at least one of the one display member constituting member and the other display member constituting member is preferably a member which generates outgas under the conditions of high temperature and high humidity and transmits water vapor, for example, a member having a plastic plate. Further, it is preferable that one of the one display member forming member and the other display member forming member includes a plastic plate and the other includes a glass plate.

The post-curing pressure-sensitive adhesive layer is a post-curing pressure-sensitive adhesive layer obtained by curing the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the above-described embodiment with active energy rays.

FIG. 2 shows a specific configuration as an example of the configuration body according to the present embodiment.
As shown in FIG. 2, the structure 2 according to the embodiment of the present invention includes a first display member forming member 21 (one display member forming member) and a second display member forming member 22 (another display member). Body constituent members) and a cured pressure-sensitive adhesive layer 11 ′ that is located between them and that bonds the first display body constituent member 21 and the second display body constituent member 22 to each other. In the structural body 2 according to the present embodiment, the first display body structural member 21 has a step on the surface of the pressure-sensitive adhesive layer 11 ′ side after curing, and specifically, has a step due to the printing layer 3. However, the present invention is not limited to this.

The cured pressure-sensitive adhesive layer 11 ′ included in the above-mentioned structure 2 is obtained by curing the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 described above by irradiation with active energy rays. The post-curing pressure-sensitive adhesive forming the post-curing pressure-sensitive adhesive layer 11′ has a crosslinked structure composed of at least the (meth)acrylic acid ester polymer (A) and the crosslinker (B), and has active energy ray curing. Containing a cured product (polymer) of the organic component (C) (preferably (meth)acrylate (C1) and (meth)acrylate (C2)), and optionally a photopolymerization initiator (D) and a silane coupling agent. (E) and an additive are further contained. Here, the active energy ray-irradiated (meth)acrylate (C1) and (meth)acrylate (C2) polymerize with each other or with each other to form a three-dimensional network structure in which the network is coarse to some extent, and ) It is presumed that a higher order structure is formed by being entangled with the crosslinked structure composed of the acrylic acid ester polymer (A) and the crosslinking agent (B). With such a structure, particularly excellent step followability and blister resistance are exhibited. Moreover, the component derived from the bifunctional (meth)acrylate (C1) having a polyalkylene glycol skeleton exhibits excellent hydrophilicity and has a skeleton that is flexible even after curing. As a result, the pressure-sensitive adhesive layer 11' after curing is also excellent in resistance to moist heat and whitening.

The photopolymerization initiator (D) contained in the post-curing pressure-sensitive adhesive that constitutes the post-curing pressure-sensitive adhesive layer 11 ′ is the same as the photopolymerization initiator (D) contained in the pressure-sensitive adhesive composition P. It remains without being cleaved by the irradiation of rays. Therefore, the content thereof is not large, and is usually 0.0001% by mass or more and 0.1% by mass or less in the adhesive, preferably 0.0001% by mass or more and 0.01% by mass or less. ..

The thickness of the pressure-sensitive adhesive layer 11 ′ after curing is basically the same as the thickness of the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1.

The gel fraction of the pressure-sensitive adhesive after curing constituting the pressure-sensitive adhesive layer 11′ after curing is preferably 50% or more, more preferably 55% or more, and particularly preferably 60% or more, and Is preferably 62% or more, more preferably 64% or more, and most preferably 67% or more. Further, the gel fraction of the pressure-sensitive adhesive after curing is preferably 95% or less, particularly preferably 90% or less, further preferably 88% or less, and most preferably 69% or less. preferable. When the gel fraction of the pressure-sensitive adhesive after curing is within the above range, the step followability and the blister resistance of the pressure-sensitive adhesive layer 11' after curing under high temperature and high humidity conditions become more excellent. The method for measuring the gel fraction of the pressure-sensitive adhesive after curing is as shown in the test example described later.

The haze value of the pressure-sensitive adhesive layer 11′ after curing is preferably 15% or less, more preferably 10% or less, particularly preferably 6% or less, and further preferably 2% or less. It is preferably at most 1%. When the haze value of the pressure-sensitive adhesive layer 11' after curing is the above, the transparency is high and it is suitable for optical use (for display). The haze value in this specification is a value measured according to JIS K7136:2000.

The constituent body 2 may be a member constituting a part of the display body such as a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, electronic paper, or the like, It may be the display itself. The display may be a touch panel.

Specifically, the first display member constituting member 21 is preferably a protective panel made of a plastic plate, a laminate including the plastic plate, or the like.

Here, in the plastic plate, the low boiling point component inside is usually vaporized when placed under high temperature conditions, for example, at 85° C., and at the interface between the plastic plate and the pressure-sensitive adhesive layer 11′ after curing, Blisters such as air bubbles, floating, and peeling may occur. However, even if the structure 2 according to the present embodiment is provided with such a plastic plate, the cured pressure-sensitive adhesive layer 11′ is derived from the pressure-sensitive adhesive sheet 1 according to the above-described embodiment, The occurrence of blisters can be suppressed well.

The plastic plate is not particularly limited, and examples thereof include acrylic resin plates such as polycarbonate resin (PC) plates and polymethylmethacrylate resin (PMMA) plates, and acrylic resin such as polymethylmethacrylate resin layers on polycarbonate resin plates. Examples include a plastic plate in which layers are laminated. The polycarbonate resin plate described above may contain a resin other than a polycarbonate resin as a constituent material thereof, and the acrylic resin plate described above may contain a resin other than an acrylic resin as a constituent material thereof. May be included.

The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5 mm, preferably 0.4 to 3 mm, particularly preferably 0.6 to 2.5 mm, and further preferably 1 to It is 2.1 mm.

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

Examples of the optical member include a shatterproof film, a polarizing plate (polarizing film), a polarizer, a retardation film (retardation film), a viewing angle compensation film, a brightness enhancement film, a contrast enhancement film, a liquid crystal polymer film, a diffusion film. , A transflective film, a transparent conductive film, and the like. Examples of the anti-scattering film include a hard coat film in which a hard coat layer is formed on one surface of a base film.

Specifically, the second display member constituting member 22 is preferably an optical member made of a glass plate, a laminated body including the glass plate, or the like. Examples of such an optical member include a display module such as a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module, an optical member as a part of the display module, or a display. Examples include a laminate including a module.

The glass plate is not particularly limited, for example, chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium-strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate Examples thereof include glass. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 10 mm, preferably 0.2 to 5 mm, and more preferably 0.8 to 2 mm.

Even if various functional layers (transparent conductive film, metal layer, silica layer, hard coat layer, antiglare layer, etc.) are provided on one side or both sides of the glass plate constituting the second display member 22. The optical members may be laminated. Moreover, the transparent conductive film and the metal layer may be patterned. The above-mentioned thing is illustrated as an optical member.

When the first display member constituting member 21 is a protective panel, the printing layer 3 is generally formed in a frame shape on the cured adhesive layer 11 ′ side of the first display member constituting member 21. is there.

The material forming the print layer 3 is not particularly limited, and a known material for printing is used. The thickness of the printing layer 3, that is, the height of the step is usually about 3 to 150 μm. The cured pressure-sensitive adhesive layer 11 ′ according to the present embodiment exhibits sufficient followability even with such a printing layer 3, and bubbles, floating, and peeling at the interface with the printing layer 3 even under high temperature and high humidity conditions. Etc. may not occur.

In order to manufacture the above-mentioned structure 2, as an example, one release sheet 12a of the pressure-sensitive adhesive sheet 1 is peeled off, and the exposed pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 is replaced with the printed layer of the first display body component 21. It is attached to the surface 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 formation of a gap or a float near 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 exposed pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 and the second display body constituent member 22 are bonded together to obtain a laminate. .. In addition, as another example, the bonding order of the first display body constituting member 21 and the second display body constituting member 22 may be exchanged.

After that, the adhesive layer 11 in the laminate is irradiated with active energy rays. As a result, the energy ray-curable component (C) ((meth)acrylate (C1) and (meth)acrylate (C2)) in the pressure-sensitive adhesive layer 11 is polymerized, and the pressure-sensitive adhesive layer 11 is cured to give a pressure-sensitive adhesive after curing. This will be layer 11'. Irradiation of energy rays to the pressure-sensitive adhesive layer 11 is usually performed through either one of the first display member forming member 21 and the second display member forming member 22, and preferably the first display member as a protective panel. Performed through the component 21.

Here, the active energy ray refers to an electromagnetic wave or a charged particle beam having an energy quantum, and specific examples thereof include ultraviolet rays and electron beams. Among the active energy rays, ultraviolet rays that are easy to handle are particularly preferable.

The irradiation of 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 such that the illuminance is about 50 to 1000 mW/cm ² . Further, the light quantity is preferably 50~10000mJ / cm ^2, more preferably 80~5000mJ / cm ^2, and particularly preferably 300~2000mJ / cm ^2. On the other hand, the electron beam irradiation can be performed by an electron beam accelerator or the like, and the irradiation amount of the electron beam is preferably about 10 to 1000 krad.

The lower limit of the adhesive strength of the cured adhesive layer 11' to soda lime glass is preferably 5 N/25 mm or more, and more preferably 10 N/25 mm or more. When the lower limit of the adhesive strength is the above, the blister resistance becomes more excellent. From the viewpoint of the step followability and the blister resistance under high temperature and high humidity conditions, it is particularly preferably 20 N/25 mm or more, more preferably 35 N/25 mm or more, and 46 N/25 mm or more. Is most preferred.

On the other hand, the upper limit of the adhesive strength is not particularly limited, but is usually preferably 80 N/25 mm or less, more preferably 70 N/25 mm or less, and particularly preferably 60 N/25 mm or less. In addition, the said adhesive force basically means the adhesive force measured by the 180 degree peeling method based on JISZ0237:2009, and a concrete test method is as showing in the test example mentioned later.

In the above-mentioned constituent 2, since the pressure-sensitive adhesive layer 11′ after curing is excellent in step followability even under high temperature and high humidity conditions, the constituent 2 is under high temperature and high humidity conditions (for example, 85° C., 85% RH, 72 hours). Even when it is placed on the surface, it is possible to suppress the occurrence of bubbles, floating, peeling, etc. near the step.

Regarding the step followability under high temperature and high humidity conditions, the cured adhesive layer 11′ preferably has a step follow rate (%) after endurance represented by the following formula of 10% or more, and 20% or more. It is more preferable to be present, particularly preferably 25% or more, further preferably 30% or more, and most preferably 40% or more. Therefore, it can be said that the step followability under high temperature and high humidity conditions is excellent. The upper limit of the step follow-up rate after endurance is not particularly limited, but is usually preferably 80% or less, and particularly preferably 70% or less.
Step-following rate after endurance (%)={(height of step (μm) in which a filled state was maintained without bubbles, floating, peeling after a predetermined durability test)/(thickness of adhesive layer)} ×100
The test method of the step follow-up rate after endurance is as shown in the test example described later.

Further, in the above-mentioned constituent 2, since the pressure-sensitive adhesive layer 11′ after curing is excellent in resistance to moist heat and whitening, the constituent 2 is placed under high temperature and high humidity conditions (for example, 85° C., 85% RH, 72 hours). After that, the whitening of the pressure-sensitive adhesive layer 11′ after curing is suppressed even if it is taken out under the conditions of normal temperature and normal humidity.

The degree of whitening can also be quantitatively evaluated by a haze value. Specifically, a non-alkali glass plate having a thickness of 0.7 mm, a pressure-sensitive adhesive layer 11′ after curing, and a polycarbonate plate having a thickness of 2 mm are laminated in that order at 85° C. and 85%. It is stored for 72 hours under the condition of RH (wet heat condition), and then taken out at room temperature and normal humidity of 23° C. and 50% RH. A value obtained by subtracting the haze value (%) before the moist heat condition from the haze value (%) after the moist heat condition (the value measured according to JIS K7136:2000; the same applies hereinafter) in the laminate (increase of the haze value after the moist heat condition). ) Can be evaluated. The increase in haze value after wet heat conditions is preferably 3 points or less, particularly preferably 2.5 points or less, and further preferably 2 points or less. Accordingly, it can be said that the wet heat and whitening resistance is excellent.

Furthermore, in the above-mentioned structure 2, since the pressure-sensitive adhesive layer 11′ after curing is also excellent in blister resistance, the structure 2 is placed under high temperature and high humidity conditions (for example, 85° C., 85% RH, 72 hours). , Even when outgas is generated from the first display member forming member 21 and/or the second display member forming member 22, air bubbles at the interface between the cured adhesive layer 11′ and the display member forming members 21 and 22, Generation of blisters such as floating and peeling is suppressed.

The embodiments described above are described to facilitate the understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above-described embodiment is intended to include all design changes and equivalents within the technical scope of the present invention.

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

Hereinafter, the present invention will be described more specifically with reference to Examples and the like, but the scope of the present invention is not limited to these Examples and the like.

[Example 1]
1. Preparation of (meth)acrylic acid ester polymer (A) 60 parts by mass of 2-ethylhexyl acrylate, 15 parts by mass of isobornyl acrylate, 10 parts by mass of N-acryloylmorpholine, and 15 parts by mass of 2-hydroxyethyl acrylate were used as solution weights. Copolymerization was carried out by a conventional method to prepare a (meth)acrylic acid ester polymer (A). When the molecular weight of this (meth)acrylic acid ester polymer (A) was measured by the method described below, the weight average molecular weight (Mw) was 600,000.

2. Preparation of Adhesive Composition 100 parts by mass of (meth)acrylic acid ester polymer (A) obtained in the above step 1 (solid content conversion value; the same applies below) and trimethylolpropane-modified triester as crosslinking agent (B) 0.2 parts by mass of diisocyanate (manufactured by Toyochem, product name "BHS8515") and polyethylene glycol #400 dimethacrylate as (meth)acrylate (C1) (manufactured by Shin-Nakamura Chemical Co., product name "NK Ester A-9G" , Weight-average molecular weight of polyethylene glycol: 400) 7 parts by mass, and ε-caprolactone-modified tris-(2-acryloxyethyl) isocyanurate as (meth)acrylate (C2) (manufactured by Shin-Nakamura Chemical Co., Ltd., product name " NK ester A-9300-1CL"), and a 1:1 (mass ratio) mixture of 1-hydroxy-cyclohexyl-phenyl-ketone as a photopolymerization initiator (D) and benzophenone (manufactured by BASF, product). 0.7 parts by mass of "OMNIRAD 500") and 0.3 parts by mass of N-glycidoxypropyltrimethoxysilane as a silane coupling agent (E) are mixed, sufficiently stirred, and diluted with methyl ethyl ketone. By doing so, a coating solution of the adhesive composition was obtained.

Here, Table 1 shows each formulation (solid content conversion value) of the adhesive composition when the (meth)acrylic acid ester polymer (A) was 100 parts by mass (solid content conversion value). Details of the abbreviations and the like shown in Table 1 are as follows.
[(Meth)acrylic acid ester polymer (A)]
2EHA: 2-ethylhexyl acrylate BA: n-butyl acrylate IBXA: isobornyl acrylate ACMO: N-acryloylmorpholine HEA: 2-hydroxyethyl acrylate 4HBA: 4-hydroxybutyl acrylate
[(Meth)acrylate (C1)]
C1-1: Polyethylene glycol #400 dimethacrylate (manufactured by Shin Nakamura Chemical Co., Ltd., product name "NK Ester A-9G", polyethylene glycol weight average molecular weight: 400)
C1-2: Polyethylene glycol #400 diacrylate (manufactured by Shin Nakamura Chemical Co., Ltd., product name "NK Ester A-400", polyethylene glycol weight average molecular weight: 400)
C1-3: polyethylene glycol #600 diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "NK Ester A-600", polyethylene glycol weight average molecular weight: 600)
PEG1000: Polyethylene glycol having a weight average molecular weight of 1000 (manufactured by Fuji Film Wako Pure Chemical Industries, product name "poly(ethylene glycol) 1000") (PEG1000 does not correspond to (meth)acrylate (C1), but for convenience ( It describes in the column of (meth)acrylate (C1).)
[Photopolymerization initiator (D)]
D1: 1:1 (hydroxy ratio) mixture of 1-hydroxy-cyclohexyl-phenyl-ketone and benzophenone (manufactured by BASF, product name "OMNIRAD 500")
D2: 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide

3. Production of pressure-sensitive adhesive sheet A heavy-release type release sheet obtained by subjecting a coating solution of the pressure-sensitive adhesive composition obtained in the above step 2 to one side of a polyethylene terephthalate film with a silicone-based release agent (manufactured by Lintec Co., Ltd., product name "SP-PET752150"). The coating layer was formed by applying a knife coater to the peel-treated surface, and then heat-treating at 80° C. for 1 minute and then at 110° C. for 1 minute. A light release type release sheet obtained by subjecting the surface of the obtained heavy release type release sheet with a coating layer on the application layer side and one side of a polyethylene terephthalate film to a release agent with a silicone release agent (manufactured by Lintec Co., Ltd., product name "SP-PET381130". )) is adhered to the release treated surface and cured at 23° C. and 50% RH for 7 days to obtain a heavy release type release sheet/active energy ray-curable pressure-sensitive adhesive layer (thickness: 50 μm)/ An adhesive sheet having the configuration of a light release type release sheet was produced.

The thickness of the pressure-sensitive adhesive layer is a value measured using a constant pressure thickness meter (manufactured by Teclock Co., Ltd., product name “PG-02”) according to JIS K7130.

[Examples 2 to 6, Comparative Examples 1 to 5]
Kind and ratio of each monomer constituting the (meth)acrylic acid ester polymer (A), kind and blending amount of (meth)acrylate (C1), blending amount of (meth)acrylate (C2), and 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 polystyrene equivalent weight average molecular weight measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).
<Measurement conditions>
・Measuring device: HLC-8320 manufactured by Tosoh Corporation
-GPC column (passed in the following order): Tosoh TSK gel superH-H
TSK gel super HM-H
TSK gel superH2000
・Measurement solvent: Tetrahydrofuran ・Measurement temperature: 40°C

[Test Example 1]
The glass transition temperature (Tg; °C) of the (meth)acrylic acid ester polymer (A) prepared in Examples and Comparative Examples was determined as a homopolymer of each monomer constituting the (meth)acrylic acid ester polymer (A). It was calculated by the FOX equation based on the glass transition temperature (Tg) of. 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), and the mass was weighed with a precision balance to obtain the above mesh. The mass of the adhesive alone was calculated by subtracting the mass of the individual. 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. After that, the adhesive was taken out, air-dried for 24 hours in an environment of a temperature of 23° C. and relative humidity of 50%, and further dried in an oven of 80° C. for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the mesh alone was subtracted to calculate the mass of the adhesive alone. The mass at this time is M2. The gel fraction (%) is represented by (M2/M1)×100. Thus, the gel fraction of the adhesive (active energy ray-curable adhesive) (before irradiation with active energy rays (UV)) was derived. The results are shown in Table 2.

On the other hand, the pressure-sensitive adhesive sheet obtained in Example 1 was irradiated with active energy rays through the light release-type release sheet under the following conditions to cure the pressure-sensitive adhesive layer to give a cured pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheets obtained in Examples 2 to 6 and Comparative Examples 1 to 4 were light release type release sheets, on which plastic plates (made by Mitsubishi Gas Chemical Co., Inc., product name "Iupilon sheet MR58U", thickness: 1 mm, containing an ultraviolet absorber) was placed on top of each other. Then, an active energy ray was irradiated through the plastic plate under the following conditions to cure the pressure-sensitive adhesive layer to obtain a cured pressure-sensitive adhesive layer. With respect to the obtained pressure-sensitive adhesive of the pressure-sensitive adhesive layer (cured pressure-sensitive adhesive), the gel fraction (after irradiation with active energy rays (UV)) was derived in the same manner as above. The results are shown in Table 2.

<Activity energy irradiation conditions>
・Using a high-pressure mercury lamp ・Illuminance 200 mW/cm ² , light intensity 1000 mJ/cm ²
・"UVPF-A1" made by iGraphics Inc. is used for UV illuminance and photometer

[Test Example 3] (Measurement of haze value)
The pressure-sensitive adhesive sheet obtained in Example 1 was irradiated with ultraviolet rays through the light-peelable release sheet under the same conditions as in Test Example 2 to cure the pressure-sensitive adhesive layer to form a cured pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheets obtained in Examples 2 to 6 and Comparative Examples 1 to 4 were light release type release sheets, on which plastic plates (made by Mitsubishi Gas Chemical Co., Inc., product name "Iupilon sheet MR58U", thickness: 1 mm, containing an ultraviolet absorber) was placed on top of each other. Then, an active energy ray was radiated through the plastic plate under the same conditions as in Test Example 2 to cure the pressure-sensitive adhesive layer to obtain a cured pressure-sensitive adhesive layer. The haze value (%) of the obtained pressure-sensitive adhesive layer after curing was measured using a haze meter (NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K7361:2000. In the pressure-sensitive adhesive sheet of Comparative Example 5, the haze value was measured for the pressure-sensitive adhesive layer that was not irradiated with active energy rays. The results are shown in Table 2.

[Test Example 4] (Measurement of adhesive strength)
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 formed by a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name "PET A4300"). , Thickness: 100 μm) to obtain an easy-adhesion layer, to obtain a laminate of heavy release type release sheet/adhesive layer/PET film. The obtained laminated body was cut into a width of 25 mm and a length of 100 mm.

Under the environment of 23° C. and 50% RH, the heavy release type release sheet is peeled off from the above laminated body, the exposed adhesive layer is attached to soda lime glass (manufactured by Nippon Sheet Glass Co., Ltd.), and put in an autoclave manufactured by Kurihara Seisakusho. And 0.5 MPa and 50° C. for 20 minutes. Then, it was left for 24 hours under the conditions of 23° C. and 50% RH.

Next, in Example 1, an active energy ray was irradiated through the heavy release type release sheet under the same conditions as in Test Example 2 to cure the pressure-sensitive adhesive layer to form a cured pressure-sensitive adhesive layer. In addition, in Examples 2 to 6 and Comparative Examples 1 to 4, a plastic plate (manufactured by Mitsubishi Gas Chemical Co., Inc., product name "Iupilon sheet MR58U", thickness: 1 mm, ultraviolet absorber was used on the heavy release type release sheet. (Containing) was piled up. Then, an active energy ray was radiated through the plastic plate under the same conditions as in Test Example 2 to cure the pressure-sensitive adhesive layer to obtain a cured pressure-sensitive adhesive layer. In Comparative Example 5, the active energy ray was not irradiated.

Then, using a tensile tester (manufactured by Orientec Co., Tensilon), the PET film/adhesive layer sample was peeled from the soda lime glass under the conditions of a peeling speed of 300 mm/min and a peeling angle of 180°, and the adhesive strength ( N/25 mm) was measured. Conditions other than those described here were measured according to JIS Z0237:2009. The results are shown in Table 2.

[Test Example 5] (Measurement of step follow-up rate)
UV curable ink (manufactured by Teikoku Ink Co., product name "POS-911 Ink") on the surface of a glass plate (manufactured by NSG Precision, product name "Corning Glass Eagle XG", length 90 mm x width 50 mm x thickness 0.5 mm). ) Was screen-printed with a predetermined thickness in a frame shape (outer shape: length 90 mm×width 50 mm, width 5 mm). Then, ultraviolet rays are irradiated (80 W/cm ² , metal halide lamp 2 lamps, lamp height 15 cm, belt speed 10 to 15 m/min) to cure the above-mentioned ultraviolet curable ink that has been printed, and a step due to printing (high step height) A glass plate with steps having a thickness of 10 μm, 12.5 μm, 15 μm, 20 μm, 25 μm, 40 μm, 60 μm, 100 μm, or 125 μm).

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 by a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., product name “PET A4300”, It was attached to an easy-adhesion layer having a thickness of 100 μm). Then, the heavy release type release sheet is peeled off to expose the pressure-sensitive adhesive layer, and each step is provided with a laminator (manufactured by Fuji Plastics, product name "LPD3214") so that the pressure-sensitive adhesive layer covers the entire frame-shaped printing surface. It was laminated on a glass plate. Then, autoclave treatment was performed for 20 minutes at 50° C. and 0.5 MPa, and the mixture was left standing at normal pressure, 23° C. and 50% RH for 24 hours.

At this stage, the initial step followability was evaluated. The step followability is judged by whether or not the printing step is completely filled with the adhesive layer, and if bubbles, floating, or peeling are observed at the interface between the printing step and the adhesive layer, the printing step It is judged that he could not follow. The initial step followability was evaluated as the initial step follow rate (%) shown by the following formula. The results are shown in Table 2.
Initial step follow-up rate (%)={(step height (μm) in which the filled state was maintained without bubbles, floating, peeling, etc.)/(thickness of adhesive layer)}×100

Next, in Example 1, an active energy ray was radiated through the PET film under the same conditions as in Test Example 2 to cure the pressure-sensitive adhesive layer to form a pressure-sensitive adhesive layer after curing. In addition, in Examples 2 to 6 and Comparative Examples 1 to 4, a plastic plate (manufactured by Mitsubishi Gas Chemical Co., Inc., product name "Iupilon sheet MR58U", thickness: 1 mm, containing an ultraviolet absorber) was placed on the PET film. I put them on top of each other. Then, an active energy ray was radiated through the plastic plate under the same conditions as in Test Example 2 to cure the pressure-sensitive adhesive layer to obtain a cured pressure-sensitive adhesive layer. In Comparative Example 5, the active energy ray was not irradiated.

Then, it was stored for 72 hours under high temperature and high humidity conditions of 85° C. and 85% RH (durability test), and then, the step followability (step followability after endurance) was evaluated in the same manner as above. The step follow-up property after endurance was evaluated as the step follow-up rate (%) after endurance represented by the following formula. The results are shown in Table 2.
Step follow-up rate after endurance (%)={(Height of step (μm) in which the filled state was maintained without bubbles, floating, peeling after the endurance test)/(thickness of adhesive layer after curing) } X 100

[Test Example 6] (Evaluation of blister resistance)
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 attached to the following plastic plate to obtain a plastic plate with a pressure-sensitive adhesive layer.
(1) Polymethylmethacrylate resin (PMMA) plate (manufactured by Mitsubishi Gas Chemical Co., Inc., product name "Iupilon sheet MR-200", thickness: 0.7 mm, no ultraviolet absorber)
(2) Polycarbonate resin (PC) plate laminated with polymethylmethacrylate resin (PMMA) layer (Mitsubishi Gas Chemical Co., Ltd., product name "Iupilon sheet MR58U", thickness: 0.7 mm, ultraviolet absorber (Contains) (Adhesive layer is attached to the polycarbonate resin plate side)
(3) Polycarbonate resin (PC) board laminated with polymethylmethacrylate resin (PMMA) layer (Mitsubishi Gas Chemical Co., Ltd., product name "Iupilon sheet HMRS53T", thickness: 2 mm, containing ultraviolet absorber) (Adhesive layer is attached to the polycarbonate resin plate side)

The heavy release type release sheet is peeled from the plastic plate with the pressure-sensitive adhesive layer obtained above, and the plastic plate is put through the exposed pressure-sensitive adhesive layer to form a soda lime glass plate having a size of 70 mm×150 mm (manufactured by Nippon Sheet Glass Co., Ltd. , Thickness: 0.7 mm). Then, autoclave treatment was performed for 20 minutes under the conditions of 50° C. and 0.5 MPa, and the mixture was allowed to stand at normal pressure, 23° C. and 50% RH for 24 hours.

Next, with respect to the pressure-sensitive adhesive layer, in Example 1, through a soda lime glass plate, in Examples 2 to 6 and Comparative Examples 1 to 4 through a plastic plate, active energy rays were applied under the same conditions as in Test Example 2. Was irradiated to cure the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive layer after curing. In this way, a structure (70 mm×150 mm) in which the plastic plate and the glass plate were bonded together by the pressure-sensitive adhesive layer after curing was obtained. Ten samples of each of the constituents were prepared.

Each sample was stored for 72 hours under high temperature and high humidity conditions of 85° C. and 85% RH. Then, the state at the interface between the adhesive layer after curing and the adherend (plastic plate, glass plate) was visually confirmed, and the blister resistance was evaluated according to the following criteria. In Comparative Example 5, the blister resistance was evaluated in the same manner as above except that the active energy ray was not irradiated. The results are shown in Table 2.
⊚: No air bubbles, floating, or peeling were observed in all 10 of the 10 samples.
◯: No air bubbles, floating, or peeling were observed in 9 to 7 samples out of 10 samples.
B: No air bubbles, floating, or peeling were observed in 6 to 1 samples out of 10 samples.
X: Floating and peeling occurred in all 10 samples.

[Test Example 7] (Evaluation of moist heat and whitening resistance)
The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples were a non-alkali glass plate having a thickness of 0.7 mm (manufactured by Corning Incorporated), a polycarbonate resin (PC) plate, and a polymethylmethacrylate resin (PMMA) layer. Was sandwiched between the laminated plastic plates (Mitsubishi Gas Chemical Co., Inc., product name “Upilon Sheet HMRS53T”, thickness: 2 mm, containing an ultraviolet absorber) to obtain a laminate.

The obtained laminate was autoclaved at 50° C. and 0.5 MPa for 30 minutes, and then left at normal pressure, 23° C. and 50% RH for 24 hours. Then, with respect to the pressure-sensitive adhesive layer of the laminate, Example 1 was over the alkali-free glass plate, Examples 2-6 and Comparative Examples 1-4 were over the plastic plate, and the same conditions as in Test Example 2 were applied. And irradiating the active energy ray to cure the pressure-sensitive adhesive layer to obtain a pressure-sensitive adhesive layer after curing. In addition, about the comparative example 5, it was set as the state which is not irradiated with an active energy ray. The haze value (%) of this laminate (sample) was measured according to JIS K7136:2000 using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name “NDH2000”).

Next, the above-mentioned laminated body was stored for 72 hours under wet heat conditions of 85° C. and 85% RH, and then allowed to stand for 24 hours at room temperature and normal humidity of 23° C. and 50% RH. The haze value (%) of the laminate was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name “NDH2000”) according to JIS K7136:2000.

Based on the above results, the haze value before the wet heat condition was subtracted from the haze value after the wet heat condition to calculate the haze value increase (point) after the wet heat condition. The results are shown in Table 2. Regarding the pressure-sensitive adhesive sheet of Comparative Example 5, there was unevenness due to phase separation of the pressure-sensitive adhesive layer (symbol * in the table).

As can be seen from Table 2, the pressure-sensitive adhesive layer after curing formed using the pressure-sensitive adhesive sheets obtained in Examples has excellent step followability and resistance to moist heat and whitening, and further has blister resistance and optical characteristics. Was also excellent.

INDUSTRIAL APPLICABILITY The pressure-sensitive adhesive sheet of the present invention can be suitably used, for example, for sticking a protective plate including a plastic plate having a step and a desired display member constituting member in manufacturing a display member.

DESCRIPTION OF SYMBOLS 1... Adhesive sheet 11... Adhesive layer 12a, 12b... Release sheet 2... Constituent body 11'... Adhesive layer after curing 21... First display body constituent member 22... Second display body constituent member 3... Printing layer

Claims (15)

An adhesive composition containing an adhesive main agent and an active energy ray-curable component,
The glass transition temperature (Tg) of the adhesive main agent is -25°C or lower,
A pressure-sensitive adhesive composition comprising, as the active energy ray-curable component, a bifunctional or trifunctional (meth)acrylate having a polyalkylene glycol skeleton. The content of the bifunctional or trifunctional (meth)acrylate having the polyalkylene glycol skeleton in the adhesive composition is 2 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the adhesive base agent. The pressure-sensitive adhesive composition according to claim 1, wherein The pressure-sensitive adhesive composition according to claim 1, wherein the adhesive main agent is a (meth)acrylic acid ester polymer (A). The pressure-sensitive adhesive composition according to claim 3, which contains a crosslinking agent (B). As the active energy ray-curable component, containing a bifunctional (meth)acrylate (C1) having a polyalkylene glycol skeleton and a trifunctional or higher functional (meth)acrylate (C2) having no polyalkylene glycol skeleton. The adhesive composition according to claim 3 or 4, characterized in that The content of the (meth)acrylate (C1) in the adhesive composition is 2 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the (meth)acrylic acid ester polymer (A). ,
The content of the (meth)acrylate (C2) in the adhesive composition is 1 part by mass or more and 15 parts by mass or less based on 100 parts by mass of the (meth)acrylic acid ester polymer (A). The adhesive composition according to claim 5, which is characterized in that The mass ratio of the content of the (meth)acrylate (C1) and the content of the (meth)acrylate (C2) in the adhesive composition is 1:0.01 to 1:5. The adhesive composition according to claim 5 or 6, wherein An active energy ray-curable pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition according to any one of claims 3 to 7. An adhesive sheet having at least an adhesive layer,
The pressure-sensitive adhesive sheet, wherein the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer is an active energy ray-curable pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition according to any one of claims 1 to 7. The pressure-sensitive adhesive sheet according to claim 9, wherein the gel fraction of the pressure-sensitive adhesive is 30% or more and 80% or less. Two release sheets,
The pressure-sensitive adhesive sheet according to claim 9 or 10, further comprising: the pressure-sensitive adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets. One display member,
Other display member,
A structure provided with a pressure-sensitive adhesive layer after curing for laminating the one display member constituting member and the other display member constituting member,
The said pressure-sensitive adhesive layer after hardening is the active energy ray cured product of the said pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet as described in any one of Claims 9-11. The structure according to claim 12, wherein at least one of the one display member forming member and the other display member forming member has a step on at least the surface on the side of the pressure-sensitive adhesive layer after curing. The composition according to claim 12 or 13, wherein a gel fraction of the pressure-sensitive adhesive after curing constituting the pressure-sensitive adhesive layer after curing is 50% or more and 95% or less. A display body constituting member and another display body constituting member are bonded together via the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to any one of claims 9 to 11 to prepare a laminate.
A method for producing a structure, comprising irradiating the pressure-sensitive adhesive layer of the laminate with an active energy ray to cure the pressure-sensitive adhesive layer to obtain a cured pressure-sensitive adhesive layer.

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