JP7148369B2 - Construct manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to an adhesive composition, an adhesive, an adhesive sheet, a structure suitable for forming a display, and a method for producing the same.

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

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

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

In addition, in the case of the conventional pressure-sensitive adhesive layer, when the pressure-sensitive adhesive layer is returned to normal temperature and normal humidity after being subjected to high-temperature and high-humidity (moist heat) conditions, the problem of whitening of the pressure-sensitive adhesive layer may occur. Therefore, the pressure-sensitive adhesive layer is also required to have wet heat whitening resistance.

In order to solve the above problems, Patent Document 1 describes 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 comprising a polymerized (meth)acrylic polymer and a cross-linking agent.

JP 2016-44293 A

However, the pressure-sensitive adhesive disclosed in Patent Literature 1 does not necessarily provide sufficient performance in conformability to irregularities and the like. In particular, in-vehicle displays are required to have higher performance because they are placed in severe environments.

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

In order to achieve the above object, firstly, the present invention provides an adhesive composition containing an adhesive main agent and an active energy ray-curable component, wherein the glass transition temperature (Tg) of the adhesive main agent is - Provided is an adhesive composition characterized by having a temperature of 25° C. or less 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 pressure-sensitive adhesive obtained is excellent in step followability and wet heat whitening resistance.

In the above invention (invention 1), the content of the bifunctional or trifunctional (meth)acrylate having the polyalkylene glycol skeleton in the adhesive composition (bifunctional (meth)acrylate having 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 main agent (Invention 2).

In the above inventions (inventions 1 and 2), the adhesive base agent is preferably a (meth)acrylic acid ester polymer (A) (invention 3).

In the above invention (invention 3), it is preferable to contain a cross-linking agent (B) (invention 4).

In the above inventions (inventions 3 and 4), the active energy ray-curable components are a bifunctional (meth)acrylate (C1) having a polyalkylene glycol skeleton and a trifunctional or higher (not having a polyalkylene glycol skeleton) ( It is preferable to contain meth)acrylate (C2) (Invention 5).

In the above invention (Invention 5), the content of the (meth)acrylate (C1) in the adhesive composition is 2 parts by mass with respect to 100 parts by mass of the (meth)acrylic acid ester polymer (A). part or more and 15 parts by mass or less, and the content of the (meth)acrylate (C2) in the adhesive composition is 1 per 100 parts by mass of the (meth)acrylic acid ester polymer (A) It is preferably from 15 parts by mass to 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) to the content of the (meth)acrylate (C2) in the adhesive composition is 1:0. It is preferably 0.01 to 1:5 (Invention 7).

The second aspect of the present invention provides an active energy ray-curable adhesive (Invention 8) obtained by crosslinking the adhesive composition (Inventions 3 to 7).

A third aspect of 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 from the pressure-sensitive adhesive composition (inventions 1 to 7) and cured with active energy rays. (Invention 9).

In the above invention (invention 9), it is preferable that the adhesive has a gel fraction of 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 be in contact with the release surfaces of the two release sheets (Invention 11).

Fourthly, the present invention provides a display body constituent member, another display body constituent member, and a post-curing adhesive layer for bonding the one display body constituent member and the other display body constituent member to each other. wherein the post-curing adhesive layer is an active energy ray-cured product of the adhesive layer of the 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 body-constituting member and the other display body-constituting member has a step on at least the post-curing adhesive layer side surface (invention 13). .

In the above inventions (Inventions 12 and 13), the gel fraction of the cured adhesive constituting the cured adhesive layer is preferably 50% or more and 95% or less (Invention 14).

Fifthly, according to the present invention, a laminate is produced by laminating one display body constituent member and another display body constituent member via the adhesive layer of the adhesive sheet (Inventions 9 to 11), There is provided a method for producing a structure, comprising irradiating the adhesive layer of the laminate with an active energy ray and curing the adhesive layer to form an adhesive layer after curing (Invention 15). .

ADVANTAGE OF THE INVENTION According to the adhesive composition, adhesive, adhesive sheet, and structure which concern on this invention, it is excellent in level|step-difference followable|trackability and wet heat whitening resistance. Moreover, according to the manufacturing method of the structure which concerns on this invention, the structure which was excellent in level|step difference followability and wet heat whitening resistance can be manufactured.

1 is a cross-sectional view of a pressure-sensitive adhesive sheet according to one embodiment of the present invention; FIG. 1 is a cross-sectional view of a construct according to an embodiment of the invention; FIG.

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

Since the adhesive composition according to the present embodiment has the above configuration, the obtained adhesive has excellent step followability and wet heat whitening resistance.

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 resulting adhesive has high flexibility. In addition, the pressure-sensitive adhesive has not yet been cured because it has not been irradiated with active energy rays, and thus retains the flexibility described above. As a result, the pressure-sensitive adhesive has excellent step followability, particularly step followability at the time of lamination (initial step followability).

From the above point of view, the glass transition temperature (Tg) of the adhesive main agent is preferably −30° C. or lower, particularly preferably −35° C. or lower. Although the lower limit of the glass transition temperature (Tg) is not particularly limited, it is preferably −100° C. or higher, particularly preferably −60° C. or higher, from the viewpoint of step conformability and blister resistance under high temperature and high humidity conditions. -40°C or higher is more 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 flexible skeleton even after curing. When such a component is present in the adhesive, even if the adhesive is placed under high temperature and high humidity conditions, moisture that has entered the adhesive under the high temperature and high humidity conditions will It is presumed that it becomes easier to remove from the adhesive, 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, since the bifunctional or trifunctional (meth)acrylate having the polyalkylene glycol skeleton also exerts an action as a plasticizer, the pressure-sensitive adhesive containing the component has more excellent step conformability during lamination. 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 is applied to an adherend and then cured by irradiation with an active energy ray to obtain a predetermined hardness and Demonstrate adhesive strength. As a result, the step followability under high-temperature and high-humidity conditions is excellent. At the same time, 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 member constituting a display body having steps, the pressure-sensitive adhesive layer is It is easy to follow the steps, and the occurrence of gaps, floats, etc. in the vicinity of the steps is suppressed. Then, after bonding the display body constituent member having the step (for example, a glass plate) and another display body constituent member (for example, a plastic plate) with the adhesive layer, the adhesive layer is irradiated with an active energy ray. It is cured to form an adhesive layer after curing. In this way, a structure is obtained in which the two display body-constituting members are pasted together with the cured adhesive layer. Even when the structure is placed under high-temperature and high-humidity conditions, for example, under conditions of 85° C. and 85% RH for 72 hours, the formation of air bubbles, floating, peeling, etc. in the vicinity of the steps is suppressed. In addition, the occurrence of blisters such as air bubbles, floating, and peeling at the interface between the pressure-sensitive adhesive layer and the display body-constituting member (especially the plastic plate) is suppressed. Furthermore, in the structure removed from the above high temperature and high humidity conditions, an increase in haze value, that is, whitening is suppressed.

In addition, in the present specification, the “step conformability” means that when a foreign substance is present between the pressure-sensitive adhesive layer and the adherend, the occurrence of air bubbles, floating, peeling, etc. around the foreign substance is suppressed. It also includes the concept of embeddability.

The type of the adhesive main agent in the adhesive composition according to the present embodiment may be any of acrylic, polyester, polyurethane, rubber, silicone, etc., from the viewpoint of step conformability and wet heat whitening resistance. Therefore, the acrylic type is preferable. Specifically, the main adhesive agent in the adhesive composition according to this embodiment is preferably the (meth)acrylic acid ester polymer (A). Therefore, the adhesive composition according to the present embodiment (hereinafter sometimes referred to as "adhesive composition P") includes a (meth)acrylic acid ester polymer (A) and a bifunctional or polyalkylene glycol skeleton having a It preferably contains an active energy ray-curable component (C) containing a trifunctional (meth)acrylate, and further preferably contains a cross-linking agent (B). In addition, the adhesive composition P contains, as the active energy ray-curable component (C), a bifunctional (meth)acrylate (C1) having a polyalkylene glycol skeleton and a trifunctional or higher (not having a polyalkylene glycol skeleton) ( It is particularly preferred 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 a cross-linking agent (B) described later via the reactive functional group derived from the reactive functional group-containing monomer, thereby resulting in a cross-linked structure (three-dimensional network structure ) is formed, and a pressure-sensitive adhesive having a predetermined cohesive strength is obtained.

The (meth)acrylic acid ester polymer (A) contains reactive functional group-containing monomers as monomer units constituting the polymer, including monomers having a hydroxyl group in the molecule (hydroxyl group-containing monomer), carboxyl groups in the molecule, A monomer having a group (carboxy group-containing monomer), a monomer having an amino group in the molecule (amino group-containing monomer), and the like are preferable. One of these reactive functional group-containing monomers may be used alone, or two or more thereof may be used in combination.

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

Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, (meth) ) hydroxyalkyl (meth)acrylates such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth)acrylate; Among them, 2-hydroxyethyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate is preferable, especially 2-hydroxyethyl acrylate or acrylic 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, particularly 8% by mass or more. preferably, more preferably 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 more excellent in step conformability and wet heat whitening resistance under high-temperature and high-humidity conditions, and has good compatibility with the active energy ray-curable component (C), and the obtained pressure-sensitive adhesive is transparent. improve sexuality.

In addition, the (meth)acrylic acid ester polymer (A) preferably contains a reactive functional group-containing monomer as the upper limit of 35% by mass or less, particularly 24% by mass, as a monomer unit constituting the polymer. It is preferable to contain the following. This makes it possible to sufficiently secure the content of the monomers other than the reactive functional group-containing monomer, and the resulting pressure-sensitive adhesive has more excellent adhesiveness. 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 to contain 20% by mass or less of the reactive functional group-containing monomer. It is most preferable to contain not more than mass %. As a result, the pressure-sensitive adhesive sheet to be obtained is superior 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 carboxyl group is an acid component, the absence of a carboxyl group-containing monomer causes problems with the adhesive to which the adhesive is attached, such as transparent conductive films such as tin-doped indium oxide (ITO), metal films, and the like. Even when a metal mesh or the like is present, it is possible to suppress the problems (corrosion, resistance value change, etc.) caused by acid.

Here, "not including a carboxy group-containing monomer" means that it does not substantially contain a carboxy group-containing monomer. It is allowed to contain a carboxyl group-containing monomer to the extent that corrosion of the metal does not occur. Specifically, the (meth)acrylic acid ester polymer (A) contains, as a monomer unit, a carboxy group-containing monomer of 0.1% by mass or less, preferably 0.01% by mass or less, more preferably 0.001% by mass. It is allowed to be contained in an amount of mass % or less.

The (meth)acrylic acid ester polymer (A) preferably contains a (meth)acrylic acid alkyl ester as a monomer unit constituting the polymer. Thereby, favorable adhesiveness can be expressed. Alkyl groups may be straight 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 (meth)acrylic acid alkyl esters having an alkyl group of 1 to 20 carbon atoms include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-(meth)acrylate, 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, and stearyl (meth)acrylate.

Among the above, from the viewpoint of efficiently imparting adhesive strength, (meth)acrylic acid alkyl esters having an alkyl group having a carbon number of 2 to 12 are more preferable, and acrylic acid alkyl esters having an alkyl group having a carbon number of 5 to 10 are preferable. is particularly preferred. Specifically, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate and isooctyl (meth)acrylate are preferred, and 2-ethylhexyl acrylate and isooctyl acrylate are more preferred. From the viewpoint of (Tg), 2-ethylhexyl acrylate is particularly preferred. These may be used alone or in combination of two or more.

From the viewpoint of imparting adhesiveness, the (meth)acrylic acid ester polymer (A) contains 40 (meth)acrylic acid alkyl esters having alkyl groups of 1 to 20 carbon atoms as monomer units constituting the polymer. It is preferably contained in an amount of 50% by mass or more, more preferably 55% by mass or more, and more preferably 55% by mass or more. In addition, from the viewpoint of ensuring the blending amount of other components, it is preferable to contain 90% by mass or less of (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms, and it is preferable to contain 85% by mass or less. More preferably, the content is particularly preferably 75% by mass or less, and more preferably 65% by mass or less.

Moreover, the (meth)acrylic acid ester polymer (A) preferably 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 groups increase the distance between the (meth)acrylic acid ester polymers (A) and increase the flexibility of the adhesive before curing with active energy rays. This makes it possible to further improve the step followability (initial step followability) during lamination. Furthermore, the pressure-sensitive adhesive after curing with active energy rays (hereinafter sometimes referred to as “post-curing pressure-sensitive adhesive”) should also be easy to exhibit flexibility and should have better conformability to unevenness under high-temperature and high-humidity conditions. can be done. In addition, due to the flexibility described above, the conformability to the adherend interface is also excellent, so that the generation of air bubbles is suppressed and the blister resistance is also excellent.

The carbocyclic ring of the alicyclic structure may be saturated or may have an unsaturated bond. The alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as bicyclic or tricyclic. The number of carbon atoms in the alicyclic structure is preferably 5-20, particularly preferably 6-15, and more preferably 7-12.

Examples of alicyclic structures include cyclohexyl skeleton, dicyclopentadiene skeleton, adamantane skeleton, isobornyl skeleton, cycloalkane skeleton (cycloheptane skeleton, cyclooctane skeleton, cyclononane skeleton, cyclodecane skeleton, cycloundecane skeleton, cyclododecane skeleton, etc.). , cycloalkene skeleton (cycloheptene skeleton, cyclooctene skeleton, etc.), norbornene skeleton, norbornadiene skeleton, polycyclic skeleton (cubane skeleton, basketane skeleton, hausan skeleton, etc.), spiro skeleton, and the like are preferred. Among them, those containing an adamantane skeleton and an isobornyl skeleton are preferable from the viewpoint of further improving step conformability.

As the alicyclic structure-containing monomer, a (meth)acrylic acid ester monomer containing the above skeleton is preferable, and specifically, cyclohexyl (meth)acrylate, dicyclopentanyl (meth)acrylate, (meth) adamantyl acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate and the like, among which adamantyl (meth)acrylate and isobornyl (meth)acrylate is preferred, and isobornyl acrylate is particularly preferred. These may be used individually by 1 type, and may be used in combination of 2 or more type.

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

In addition, in the (meth)acrylic acid ester polymer (A), the content of the alicyclic structure-containing monomer is preferably 30% by mass or less, from the viewpoint of ensuring the blending amount of other components, and 22% by mass. It is more preferable that the content be 18% by mass or less, and particularly preferably 18% by mass or less.

Moreover, the (meth)acrylic acid ester polymer (A) preferably contains a nitrogen atom-containing monomer as a monomer unit constituting the polymer. Adhesion to adherends such as glass can be improved by containing a nitrogen atom-containing monomer. Examples of nitrogen atom-containing monomers include monomers having an amino group, monomers having an amide group, and monomers having a nitrogen-containing heterocyclic ring. Among them, monomers having a nitrogen-containing heterocyclic ring are preferred. In addition, from the viewpoint of increasing the degree of freedom of the portion derived from the nitrogen atom-containing monomer in the higher-order structure of the pressure-sensitive adhesive, the nitrogen atom-containing monomer forms the (meth)acrylic acid ester polymer (A). preferably contains no reactive unsaturated double bond groups other than the one polymerizable group used in the polymerization of .

Examples of monomers having a nitrogen-containing heterocyclic ring include N-(meth)acryloylmorpholine, N-vinyl-2-pyrrolidone, N-(meth)acryloylpyrrolidone, N-(meth)acryloylpiperidine, N-(meth)acryloyl pyrrolidine, N-(meth)acryloylaziridine, aziridinylethyl (meth)acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc. Among them, N-(meth)acryloylmorpholine, which exhibits superior adhesive strength, is preferred, and N-acryloylmorpholine is particularly preferred.

Examples of nitrogen atom-containing monomers include (meth)acrylamide, N-methyl(meth)acrylamide, N-methylol(meth)acrylamide, N-tert-butyl(meth)acrylamide, and N,N-dimethyl(meth)acrylamide. , N,N-ethyl (meth)acrylamide, N,N-dimethylaminopropyl (meth)acrylamide, N-isopropyl (meth)acrylamide, N-phenyl (meth)acrylamide, dimethylaminopropyl (meth)acrylamide, N-vinyl Caprolactam, monomethylaminoethyl (meth)acrylate, monoethylaminoethyl (meth)acrylate, monomethylaminopropyl (meth)acrylate, monoethylaminopropyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, etc. can also be used.
One type of the above nitrogen atom-containing monomer may be used alone, or two or more types may be used in combination.

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. preferably 4% by mass or more, and particularly preferably 8% by mass or more. In addition, 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 ensuring the blending amount of other components. is particularly preferred.

The (meth)acrylate polymer (A) is preferably a solution polymer obtained by a solution polymerization method. Since it is a solution polymer, it is easy to obtain a high-molecular-weight polymer, and a pressure-sensitive adhesive with excellent conformability to unevenness 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 weight-average molecular weight of the (meth)acrylate polymer (A) is preferably 200,000 or more, particularly preferably 300,000 or more, further preferably 400,000 or more as a lower limit. When the lower limit of the weight-average molecular weight of the (meth)acrylic acid ester polymer (A) is above, the pressure-sensitive adhesive to be obtained has more excellent conformability to irregularities under high-temperature and high-humidity conditions.

In addition, the weight average molecular weight of the (meth)acrylic acid ester polymer (A) is preferably 900,000 or less, particularly preferably 850,000 or less, further preferably 800,000 or less as an upper limit. preferable. When the weight-average molecular weight of the (meth)acrylic acid ester polymer (A) is within the above range, the pressure-sensitive adhesive to be obtained has more excellent conformability to irregularities in the initial stage. 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.

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 further is preferably 80% by mass or more. 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. . When 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 wet heat whitening resistance are improved. will be excellent.

(2) Crosslinking agent (B)
The cross-linking agent (B) cross-links the (meth)acrylic acid ester polymer (A) by heating the pressure-sensitive adhesive composition P, making it possible to satisfactorily form a cross-linked structure of a three-dimensional network structure. As a result, a pressure-sensitive adhesive having a predetermined cohesive force is obtained, and the step followability and blistering resistance under high-temperature and high-humidity conditions are further improved.

The cross-linking agent (B) may be one that reacts with the reactive functional group of the (meth)acrylic acid ester polymer (A). agent, melamine cross-linking agent, aziridine cross-linking agent, hydrazine cross-linking agent, aldehyde cross-linking agent, oxazoline cross-linking agent, metal alkoxide cross-linking agent, metal chelate cross-linking agent, metal salt cross-linking agent, ammonium salt cross-linking agent etc. Here, when the (meth)acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer as a constituent monomer unit, an isocyanate-based cross-linking agent having excellent reactivity with hydroxyl groups is used as the cross-linking agent (B). It is preferred to use In addition, a crosslinking agent (B) can be used individually by 1 type or in combination of 2 or more types.

The isocyanate-based cross-linking agent contains at least a polyisocyanate compound. Examples of polyisocyanate compounds include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, and alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate. , and their biuret, isocyanurate, 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 hydroxyl groups.

The content of the cross-linking agent (B) in the adhesive composition P is preferably 0.01 parts by mass or more, particularly 0.01 part by mass, based on 100 parts by mass of the (meth)acrylic acid ester polymer (A). 05 parts by mass or more, and more preferably 0.1 parts by mass or more. In addition, the content is preferably 1.0 parts by mass or less, particularly preferably 0.8 parts by mass or less, and further preferably 0.5 parts by mass or less. When the content of the cross-linking agent (B) is within the above range, a predetermined cross-linked structure is formed, and the pressure-sensitive adhesive to be obtained has more excellent conformability to unevenness 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 adhesive obtained by cross-linking the adhesive composition P, the active energy ray-curable component (C) remains unreacted. When the adhesive is irradiated with an active energy ray, the active energy ray-curable component (C) in the adhesive is polymerized by cleavage of the unsaturated double bond, thereby curing the adhesive.

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 may have a polyalkylene glycol skeleton. It may contain only a trifunctional (meth) acrylate, or it may contain a bifunctional (meth) acrylate having a polyalkylene glycol skeleton and a trifunctional (meth) acrylate having a polyalkylene glycol skeleton. Alternatively, it contains a bifunctional (meth)acrylate having a polyalkylene glycol skeleton and/or a trifunctional (meth)acrylate having a polyalkylene glycol skeleton and a (meth)acrylate having no polyalkylene glycol skeleton. good too. The (meth)acrylate having no polyalkylene glycol skeleton may be monofunctional, bifunctional, or trifunctional or higher. 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 (meth)acrylate (C2) having no polyalkylene glycol skeleton.

The active energy ray-curable component (C) contains a bifunctional (meth)acrylate (C1) having a polyalkylene glycol skeleton and a trifunctional or higher (meth)acrylate (C2) having no polyalkylene glycol skeleton. When the adhesive obtained by cross-linking the adhesive composition P is irradiated with an active energy ray, the C1 components and the C2 components are polymerized with each other, or the C1 component and the C2 component are polymerized.

When containing a bifunctional (meth) acrylate (C1) having a polyalkylene glycol skeleton as described above and a trifunctional or more (meth) acrylate (C2) having no polyalkylene glycol skeleton, the adhesive after curing is a structure that expresses flexibility derived from a bifunctional (meth)acrylate (C1) having a polyalkylene glycol skeleton, and a trifunctional or higher (meth)acrylate (C2) that does not have a polyalkylene glycol skeleton. It has a crosslinked structure that also has a rigid structure. As a result, it is possible to obtain a post-curing adhesive that has both moderate flexibility and cohesive strength, and it is possible to improve step conformability under high-temperature and high-humidity conditions, as well as blister resistance. can be made better.

(3-1) (meth) acrylate (C1)
(Meth)acrylate (C1) in the present embodiment is a bifunctional (meth)acrylate having a polyalkylene glycol skeleton. Examples of 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 wet heat whitening resistance.

The weight average molecular weight of the polyalkylene glycol skeleton is preferably 100 or more, particularly preferably 150 or more, further preferably 200 or more. Further, the weight-average molecular weight of the polyalkylene glycol skeleton is preferably 5000 or less, particularly preferably 4000 or less, and further preferably 3000 or less. It is preferably less than 1000, particularly preferably 800 or less, most preferably 500 or less. When the weight-average molecular weight of the polyalkylene glycol skeleton is within the above range, the wet heat whitening resistance and step followability become more excellent. In addition, it has excellent compatibility with other components (especially the acrylic acid ester copolymer (A)), and can improve the optical properties (haze value) of the pressure-sensitive adhesive.

(Meth)acrylate (C1) includes, for example, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, polytetramethylene glycol di(meth)acrylate, polyisobutylene glycol (meth)acrylate, and the like. Among these, polyethylene glycol diacrylate or polyethylene glycol dimethacrylate is preferable from the viewpoint of wet heat whitening resistance and step conformability, and polyethylene glycol dimethacrylate is particularly preferable from the viewpoint of blister resistance. These may be used individually by 1 type, and may be used in combination of 2 or more type.

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 even more preferably 6 parts by mass or more. The 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 cured pressure-sensitive adhesive has more excellent wet heat whitening resistance and conformability to unevenness.

(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. Although the upper limit of the number of unsaturated double bonds is not particularly limited, it is usually preferably 9 or less, particularly preferably 6 or less, and further preferably 4 or less.

(Meth)acrylates (C2) include, for example, trimethylolpropane tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, propionic acid-modified dipentaerythritol tri(meth)acrylate, pentaerythritol tri(meth)acrylate, Trifunctional types such as propylene oxide-modified trimethylolpropane tri(meth)acrylate, tris(acryloxyethyl)isocyanurate, ε-caprolactone-modified tris-(2-(meth)acryloxyethyl)isocyanurate; ) acrylate, pentaerythritol tetra (meth) acrylate; pentafunctional such as propionic acid-modified dipentaerythritol penta (meth) acrylate; dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) ) hexafunctional type such as acrylate. These may be used individually by 1 type, and may be used in combination of 2 or more type. 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, trifunctional (meth)acrylates are preferable from the viewpoint of step conformability and blistering resistance under high-temperature and high-humidity conditions of the adhesive after curing. In particular, trifunctional (meth)acrylates having an isocyanurate structure in the molecule ( Meth)acrylates are preferred. Specifically, ε-caprolactone-modified tris-(2-(meth)acryloxyethyl)isocyanurate is preferred, and ε-caprolactone-modified tris-(2-acryloxyethyl)isocyanurate is particularly preferred.

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 preferably 3 parts by mass or more, and more preferably 3 parts by mass or more. The 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 level difference followability and blister resistance of the cured pressure-sensitive adhesive become more excellent.

Further, the mass ratio of the (meth)acrylate (C1) content 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. :0.4 to 1:0.7 is most preferred. When the mass ratio is within the above range, the wet heat whitening resistance and step followability can be made more excellent.

Furthermore, 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 wet heat whitening resistance and step followability. From the viewpoint of improving the properties, the lower limit is preferably 1 part by mass or more, preferably 5 parts by mass or more, relative to 100 parts by mass of the (meth)acrylic acid ester polymer (A). More preferably, it is 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 upper limit of the content is preferably 30 parts by mass or less, more preferably 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) Photoinitiator (D)
When ultraviolet rays are used for curing 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 containing the photopolymerization initiator (D) in this way, the active energy ray-curable component (C) can be efficiently polymerized, and the polymerization curing time and the irradiation dose of the active energy ray can be reduced. 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-tertiary-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2 , 4-diethylthioxanthone, benzyl dimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, 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, phosphine oxide-based photopolymerization initiators are preferable because they are easily cleaved and easily cure the adhesive even when irradiated with ultraviolet rays through a plastic plate containing an ultraviolet absorber. Specifically, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide and the like are preferred.

The content of the photopolymerization initiator (D) in the adhesive composition P is preferably 1 part by mass or more, particularly 3 parts by mass or more, relative to 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. parts by mass or less, and most preferably 7 parts by mass or less.

(5) Silane coupling agent (E)
The adhesive composition P preferably further contains a silane coupling agent (E). As a result, even if the adherend is a plastic plate or a glass member, the adhesiveness to the adherend is improved, and step followability and 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 exhibits light transmittance. It is preferable to have

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

The content of the silane coupling agent (E) in the adhesive composition P is preferably 0.01 parts by mass or more with respect to 100 parts by mass of the (meth)acrylic acid ester polymer (A), particularly It is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more. Also, 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 The adhesive composition P may optionally contain various additives commonly used in acrylic adhesives, such as ultraviolet absorbers, antistatic agents, tackifiers, antioxidants, and light stabilizers. Agents, softeners, fillers, refractive index modifiers, rust preventives and the like can be added. It should be noted that a polymerization solvent and a dilution solvent, which will be described later, are not included in the additives constituting the adhesive composition P.

2. Production of Adhesive Composition The adhesive composition P is produced by producing a (meth)acrylic acid ester polymer (A), and the resulting (meth)acrylic acid ester polymer (A), a cross-linking agent (B) and , Active energy ray-curable component (C) ((meth) acrylate (C1) and (meth) acrylate (C2)) is mixed, and if desired, a photopolymerization initiator (D), a silane coupling agent (E ) and additives.

The (meth)acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a conventional radical polymerization method. 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 may be polymerized without a solvent. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, and methyl ethyl ketone, and two or more of them may be used in combination.

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

Examples of organic peroxides include benzoyl peroxide, t-butylperbenzoate, cumene hydroperoxide, diisopropylperoxydicarbonate, di-n-propylperoxydicarbonate, di(2-ethoxyethyl)peroxy dicarbonate, t-butylperoxyneodecanoate, t-butylperoxybivalate, (3,5,5-trimethylhexanoyl)peroxide, dipropionylperoxide, diacetylperoxide and the like.

The weight average molecular weight of the resulting polymer can be adjusted by adding a chain transfer agent such as 2-mercaptoethanol in the polymerization step.

When the (meth)acrylic ester polymer (A) is obtained, the solution of the (meth)acrylic ester polymer (A) is added with the crosslinking agent (B), the active energy ray-curable component (C) ((meth) Acrylate (C1) and (meth)acrylate (C2)), and optionally photoinitiator (D), silane coupling agent (E), additives are added and mixed thoroughly to dilute with a solvent. A second adhesive composition P (coating solution) can be obtained. In any of the above components, if a solid one is used, or if precipitation occurs when mixed with other components in an undiluted state, the component is added alone in advance to a dilution solvent. It may be dissolved or diluted prior to mixing with other ingredients.

Examples of the diluting solvent include aliphatic hydrocarbons such as hexane, heptane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; halogenated hydrocarbons such as methylene chloride and ethylene chloride; 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 is within a range that allows coating, and can be appropriately selected according to the situation. For example, the adhesive composition P is diluted to a concentration of 10 to 60% by mass. When obtaining the coating solution, the addition of a diluent solvent or the like is not a necessary condition, and the diluent solvent may not be added as long as the viscosity of the adhesive composition P allows coating. In this case, the adhesive composition P becomes a coating solution in which the polymerization solvent for the (meth)acrylic acid ester polymer (A) is used as the diluting solvent.

[Adhesive]
The pressure-sensitive adhesive according to this embodiment is obtained from the pressure-sensitive adhesive composition according to the embodiment described above, preferably by cross-linking (thermally cross-linking) the pressure-sensitive adhesive composition P described above. The (meth)acrylic acid ester polymer (A) in the 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) exists in the adhesive as it is without curing. Therefore, the pressure-sensitive adhesive according to this embodiment is an active energy ray-curable pressure-sensitive adhesive that has the property of being cured by irradiation with an active energy ray.

Crosslinking of the adhesive composition P can usually be performed by heat treatment. This heat treatment can also serve as a drying treatment for volatilizing the diluent solvent and the like 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, particularly preferably 70 to 120°C. The heating time is preferably 10 seconds to 10 minutes, more preferably 50 seconds to 5 minutes.

After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be provided at room temperature (eg, 23° C., 50% RH). If the curing period is required, the adhesive is formed after the curing period has elapsed, and if the curing period is not required, the adhesive is formed after the heat treatment is completed.

By the above heat treatment (and curing), the (meth)acrylic acid ester polymer (A) is satisfactorily crosslinked via the crosslinking agent (B). In addition, the active energy ray-curable component (C) is contained in the pressure-sensitive adhesive as it is unreacted.

[Adhesive sheet]
A pressure-sensitive adhesive sheet according to an embodiment of the present invention comprises 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 bonding one member and another member. It is preferably used when there is a step, and further when at least one of the members generates outgas or permeates water vapor under high-temperature and high-humidity conditions. A hard body is preferably used as the member. Moreover, as the above-mentioned member, a member constituting a display body is preferably mentioned. Therefore, the pressure-sensitive adhesive sheet according to the present embodiment is preferably used for optical applications, but it is not limited to this.

FIG. 1 shows a specific configuration as an example of the pressure-sensitive adhesive sheet according to this embodiment.
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 and 12a so as to be in contact with the release surfaces of the two release sheets 12a and 12b. , 12b and an active energy ray-curable adhesive layer 11 sandwiched between them. In this specification, the release surface of the release sheet refers to the surface of the release sheet that has releasability, and includes both the surface that has been subjected to a release treatment and the surface that exhibits releasability without being subjected to a release treatment. .

1. Each member 1-1. Adhesive Layer The adhesive constituting the adhesive layer 11 is the adhesive according to the embodiment described above. That is, it is preferably an adhesive obtained by cross-linking (thermally cross-linking) the adhesive composition P described above.

The lower limit of the thickness of the pressure-sensitive adhesive layer 11 (value measured according to JIS K7130) is preferably 15 μm or more, more preferably 30 μm or more, and particularly preferably 50 μm or more. The upper limit of the thickness of the adhesive layer 11 is preferably 400 μm or less, 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 wet heat whitening resistance will be more excellent.

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

Examples of the release sheets 12a and 12b include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate film, and polybutylene. Terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene/(meth)acrylic acid copolymer film, ethylene/(meth)acrylic acid ester copolymer film, polystyrene film, polycarbonate film, polyimide film, fluorine A resin film or the like is used. Crosslinked films of these are also used. Furthermore, a laminated film of these may be used.

The release surfaces of the release sheets 12a and 12b (especially the surfaces in contact with the pressure-sensitive adhesive layer 11) are preferably subjected to a release treatment. Examples of release agents used in the release treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based release agents. Of the release sheets 12a and 12b, it is preferable that one of the release sheets is a heavy release type release sheet with a large release force, and the other release sheet is a light release type release sheet with a small release force.

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

2. Manufacture of Adhesive Sheet As an example of manufacturing the adhesive sheet 1, the coating solution of the adhesive composition P is applied to the release surface of one of the release sheets 12a (or 12b) and heat-treated to form the adhesive composition. After thermally cross-linking P to form a coating layer, the release surface of the other release sheet 12b (or 12a) is superposed on the coating layer. If a curing period is necessary, the curing period is set, and if the curing period is not necessary, the coating layer becomes the active energy ray-curable adhesive layer 11 as it is. As a result, the pressure-sensitive adhesive sheet 1 is obtained. The conditions for heat treatment and curing are as described above.

As another production example of the adhesive sheet 1, the coating solution of the adhesive composition P is applied to the release surface of one release sheet 12a, heat treatment is performed to thermally crosslink the adhesive composition P, and the coating is performed. A layer is formed to obtain a release sheet 12a with a coating layer. Further, the coating solution of the adhesive composition P is applied to the release surface of the other release sheet 12b, and heat treatment is performed to thermally crosslink the adhesive composition P to form a coating layer. 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 pasted together so that both coating layers are in contact with each other. If a curing period is required, the curing period is set, and if the curing period is not required, the laminated coating layer becomes the active energy ray-curable adhesive layer 11 as it is. As a result, the pressure-sensitive adhesive sheet 1 is obtained. According to this production example, even when the pressure-sensitive adhesive layer 11 is thick, it is possible to produce stably.

As a method for 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 adhesive (before active energy ray irradiation) constituting the adhesive layer 11 is preferably 30% or more as a lower limit, particularly 35%. It is preferably 40% or more, more preferably 40% or more. If the lower limit of the gel fraction of the adhesive is above, the adhesive will have a predetermined cohesive force, and the adhesive will adhere to the blade when cutting the adhesive sheet 1, or during storage. For example, the seepage of the adhesive from the adhesive layer 11 is effectively suppressed. The upper limit of the gel fraction of the pressure-sensitive adhesive is preferably 80% or less, 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 conformability to unevenness is excellent. In addition, the cured pressure-sensitive adhesive after irradiation with active energy rays does not become too hard, and the step conformability of the cured pressure-sensitive adhesive layer under high-temperature and high-humidity conditions becomes more excellent. The method for measuring the gel fraction of this active energy ray-curable pressure-sensitive adhesive is as shown in the test examples described later.

The increase in the gel fraction accompanying 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 preferably 10 points or more. Preferably. By increasing the gel fraction in this manner, the cured pressure-sensitive adhesive layer to be obtained has excellent conformability to unevenness under high-temperature and high-humidity conditions. The upper limit of the increase in the gel fraction is not particularly limited, but from the viewpoint of preventing the adhesive layer from becoming too hard after curing, the increase in the gel fraction is preferably 45 points or less. , particularly preferably 40 points or less, more preferably 35 points or less.

(2) Initial level difference followability With regard to the level difference followability at the time of lamination, the pressure-sensitive adhesive layer 11 preferably has an initial level difference followability rate (%) of 30% or more, particularly 40%, as shown by the following formula. % or more, more preferably 50% or more. Accordingly, it can be said that the step followability (initial step followability) at the time of lamination is excellent. Although the upper limit of the step follow-up rate in the initial stage is not particularly limited, it is usually preferably 80% or less, and particularly preferably 70% or less.
Initial level difference follow-up rate (%) = {(height of level difference maintained in a buried state without air bubbles, floating, peeling, etc. (μm)) / (thickness of adhesive layer)} x 100
The test method for the initial step followability rate is as shown in the test examples described later.

[Construction]
A structure according to one embodiment of the present invention is a post-curing adhesive for laminating one display body constituting member, another display body constituting member, and one display body constituting member and another display body constituting member. and an agent layer. The structure according to the present embodiment may be one member constituting the display body, or may be the display body itself.

It is preferable that at least one of the one display body constituent member and the other display body constituent member has a step on at least the pressure-sensitive adhesive layer side surface. At least one of the one display body component and the other display body component is preferably a member that generates outgas or permeates water vapor under high temperature and high humidity conditions, such as a member provided with a plastic plate. Furthermore, it is preferable that one of the one display body component and the other display body component has a plastic plate and the other has 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 embodiment described above with an active energy ray.

FIG. 2 shows a specific configuration as an example of the configuration according to this embodiment.
As shown in FIG. 2, the structure 2 according to one embodiment of the present invention includes a first display body forming member 21 (one display body forming member) and a second display body forming member 22 (another display body forming member). and a post-curing adhesive layer 11' positioned therebetween for adhering the first display body-constituting member 21 and the second display body-constituting member 22 to each other. In the structure 2 according to the present embodiment, the first display body-constituting member 21 has a step on the surface on the side of the adhesive layer 11 ′ after curing. Specifically, the printed layer 3 has a step. However, it is not limited to this.

The post-curing adhesive layer 11 ′ of the structure 2 is obtained by curing the adhesive layer 11 of the adhesive sheet 1 described above by irradiating active energy rays. The post-curing adhesive that constitutes the post-curing adhesive layer 11′ has a crosslinked structure composed of at least a (meth)acrylic acid ester polymer (A) and a crosslinking agent (B), and is active energy ray-curable. (C) (preferably (meth) acrylate (C1) and (meth) acrylate (C2)) cured product (polymer), optionally a photopolymerization initiator (D), a silane coupling agent It further contains (E) and additives. Here, the (meth)acrylate (C1) and (meth)acrylate (C2) irradiated with active energy rays are polymerized individually or with each other to form a three-dimensional network structure in which the network is somewhat coarse, and (meth) ) It is presumed to form a higher-order structure by entangling with the crosslinked structure composed of the acrylic acid ester polymer (A) and the crosslinker (B). Such a structure exhibits particularly excellent step followability and blister resistance. In addition, the component derived from the bifunctional (meth)acrylate (C1) having a polyalkylene glycol skeleton exhibits excellent hydrophilicity and has a flexible skeleton even after curing. As a result, the post-curing pressure-sensitive adhesive layer 11 ′ is also excellent in wet heat whitening resistance.

The photopolymerization initiator (D) contained in the post-curing adhesive constituting the post-curing pressure-sensitive adhesive layer 11′ is the photopolymerization initiator (D) contained in the adhesive composition P. It remained without being cleaved even by radiation irradiation. Therefore, its content is not large, and is usually 0.00001% by mass or more and 0.1% by mass or less, preferably 0.0001% by mass or more and 0.01% by mass or less in the adhesive. .

The thickness of the cured adhesive layer 11 ′ is basically the same as the thickness of the adhesive layer 11 of the adhesive sheet 1 .

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

The haze value of the 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. Preferably, it is 1% or less, most preferably. When the cured pressure-sensitive adhesive layer 11 ′ has the above haze value, it has high transparency and is suitable for optical applications (for displays). The haze value in this specification is a value measured according to JIS K7136:2000.

The structure 2 may be, for example, a liquid crystal (LCD) display, a light emitting diode (LED) display, an organic electroluminescence (organic EL) display, a member that constitutes a part of a display such as electronic paper, The display body itself may be used. Note that 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 or a laminate including a plastic plate.

Here, when the plastic plate is usually placed under high temperature conditions, for example, 85° C., the internal low boiling point component evaporates, and at the interface between the plastic plate and the post-curing pressure-sensitive adhesive layer 11′, There is a possibility that blisters such as air bubbles, floating, and peeling may occur. However, even if the structure 2 according to the present embodiment includes such a plastic plate, the post-curing adhesive layer 11' is derived from the adhesive sheet 1 according to the embodiment described above. It is possible to satisfactorily suppress the occurrence of blisters.

The plastic plate is not particularly limited, and examples thereof include acrylic resin plates such as a polycarbonate resin (PC) plate and a polymethyl methacrylate resin (PMMA) plate, acrylic resin such as a polymethyl methacrylate resin layer on a polycarbonate resin plate. Examples include a plastic plate having laminated layers. The above-mentioned polycarbonate resin plate may contain a resin other than polycarbonate resin as a constituent material, and the above-mentioned acrylic resin plate may contain a resin other than acrylic resin as a constituent material. may contain.

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 more preferably 1 to 5 mm. 2.1 mm.

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

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

Specifically, the second display member constituting member 22 is preferably an optical member made of a glass plate or a laminate including a glass plate. Examples of such optical members include display modules such as liquid crystal (LCD) modules, light emitting diode (LED) modules, organic electroluminescence (organic EL) modules, optical members as part of display modules, or display modules. Laminates containing modules can be mentioned.

The glass plate is not particularly limited, and examples thereof include chemically strengthened glass, alkali-free glass, quartz glass, soda lime glass, barium-strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, and barium borosilicate. Glass etc. are mentioned. The thickness of the glass plate is not particularly limited, but is usually 0.1 to 10 mm, preferably 0.2 to 5 mm, more preferably 0.8 to 2 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 glass plate constituting the second display member constituting member 22. Alternatively, optical members may be laminated. Moreover, the transparent conductive film and the metal layer may be patterned. Examples of the optical member include those described above.

When the first display body-constituting member 21 is a protective panel, the print layer 3 is generally formed in a frame shape on the post-curing adhesive layer 11' side of the first display body-constituting member 21. be.

The material constituting the printing layer 3 is not particularly limited, and known materials for printing are used. The thickness of the printing layer 3, that is, the height of the step is usually about 3 to 150 μm. The post-curing pressure-sensitive adhesive layer 11′ in this embodiment exhibits sufficient conformability to such a printed layer 3, and even under high-temperature and high-humidity conditions, air bubbles, floating, and peeling occur at the interface with the printed layer 3. etc. will not occur.

In order to manufacture the structure 2, as an example, one release sheet 12a of the adhesive sheet 1 is peeled off, and the exposed adhesive layer 11 of the adhesive sheet 1 is transferred to the printed layer of the first display body constituent member 21. 3 is pasted on the side on which 3 is present. At this time, since the pressure-sensitive adhesive layer 11 is excellent in initial step followability, the occurrence of gaps and floats near the step due to the printed layer 3 is suppressed.

Next, the other release sheet 12b is peeled off from the adhesive layer 11 of the adhesive sheet 1, and the exposed adhesive layer 11 of the adhesive sheet 1 and the second display member constituting member 22 are laminated to obtain a laminate. . As another example, the bonding order of the first display body forming member 21 and the second display body forming member 22 may be changed.

After that, the adhesive layer 11 in the laminate is irradiated with an active energy ray. As a result, the energy ray-curable component (C) ((meth)acrylate (C1) and (meth)acrylate (C2)) in the adhesive layer 11 is polymerized, and the adhesive layer 11 is cured to form an adhesive after curing. It becomes layer 11'. Irradiation of energy rays to the pressure-sensitive adhesive layer 11 is usually carried out through either the first display member constituting member 21 or the second display member constituting member 22, preferably through the first display member as a protective panel. It is carried out over the constituent member 21 .

Here, the active energy ray refers to an electromagnetic wave or a charged particle beam that has energy quanta, and specifically includes ultraviolet rays, electron beams, and the like. Among active energy rays, ultraviolet rays are particularly preferable because they are easy to handle.

Irradiation with ultraviolet rays can be performed by a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, or the like, and the irradiation amount of ultraviolet rays is preferably about 50 to 1000 mW/cm ² . Also, the amount of light is preferably 50 to 10000 mJ/cm ² , more preferably 80 to 5000 mJ/cm ² and particularly preferably 300 to 2000 mJ/cm ² . On the other hand, electron beam irradiation can be performed by an electron beam accelerator or the like, and the electron beam irradiation dose 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, more preferably 10 N/25 mm or more. When the lower limit of the adhesive strength is above, the blister resistance becomes more excellent. From the viewpoint of step followability and 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. The adhesive strength is basically the adhesive strength measured by the 180-degree peeling method according to JIS Z0237:2009, and the specific test method is as shown in the test examples described later.

In the composition 2, since the post-curing adhesive layer 11′ has excellent step followability even under high temperature and high humidity conditions, the composition 2 can be cured under high temperature and high humidity conditions (for example, 85 ° C., 85% RH, 72 hours). Even when placed on a flat surface, the occurrence of air bubbles, floating, peeling, etc. in the vicinity of the step is suppressed.

Regarding the unevenness conformability under high-temperature and high-humidity conditions, the post-curing pressure-sensitive adhesive layer 11' preferably has a unevenness following rate (%) after durability shown by the following formula of 10% or more, and preferably 20% or more. It is more preferably 25% or more, particularly preferably 30% or more, and most preferably 40% or more. Therefore, it can be said that the step followability is excellent under high temperature and high humidity conditions. Although the upper limit of the step follow-up rate after durability is not particularly limited, it is usually preferably 80% or less, and particularly preferably 70% or less.
Level difference follow-up rate after endurance (%) = {(height of level difference maintained in a buried state without air bubbles, floating, peeling, etc. after predetermined endurance test (μm))/(thickness of adhesive layer)} ×100
The test method for the step followability after the endurance test is as shown in the test examples to be described later.

In addition, in the composition 2, since the post-curing adhesive layer 11′ is excellent in wet heat whitening resistance, the composition 2 is placed under high temperature and high humidity conditions (for example, 85° C., 85% RH, 72 hours). After curing, whitening of the cured pressure-sensitive adhesive layer 11' is suppressed even when the adhesive layer 11' is taken out under normal temperature and humidity conditions.

The degree of whitening can also be quantitatively evaluated by the haze value. Specifically, a laminate obtained by laminating an alkali-free glass plate with a thickness of 0.7 mm, an adhesive layer 11' after curing, and a polycarbonate plate with a thickness of 2 mm in that order was heated at 85 ° C. and 85% It is stored for 72 hours under RH conditions (wet heat conditions), and then taken out at normal temperature and normal humidity of 23° C. and 50% RH. The value obtained by subtracting the haze value (%) before the wet heat condition from the haze value (%) after the wet heat condition in the laminate (the value measured according to JIS K7136: 2000; the same applies hereinafter) (increase in the haze value after the wet heat condition ) can be evaluated by The haze value increase after the moist 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 whitening resistance is excellent.

Furthermore, in the composition 2, since the post-curing adhesive layer 11' is also excellent in blister resistance, the composition 2 is placed under high temperature and high humidity conditions (for example, 85° C., 85% RH, 72 hours). , even when outgassing is generated from the first display body constituting member 21 and/or the second display body constituting member 22, air bubbles at the interface between the post-curing pressure-sensitive adhesive layer 11′ and the display body constituting members 21 and 22, The occurrence of blisters such as floating and peeling is suppressed.

The embodiments described above are described to facilitate understanding of the present invention, and are not described to limit the present invention. Therefore, each element disclosed in the above embodiments is meant to include all design changes and equivalents that fall 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. Further, the first display member constituting member 21 may have steps other than the printed layer 3, or may not have steps. Furthermore, not only the first display body constituent member 21 but also the second display body constituent member 22 may have a step on the post-curing adhesive layer 11' side.

EXAMPLES The present invention will be described in more detail 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)acrylate polymer (A) 60 parts by weight of 2-ethylhexyl acrylate, 15 parts by weight of isobornyl acrylate, 10 parts by weight of N-acryloylmorpholine, and 15 parts by weight of 2-hydroxyethyl acrylate were solution-weighted. A (meth)acrylic acid ester polymer (A) was prepared by copolymerization according to a method. When the molecular weight of this (meth)acrylic acid ester polymer (A) was measured by the method described later, it was found to have a weight average molecular weight (Mw) of 600,000.

2. Preparation of adhesive composition 100 parts by mass of the (meth)acrylic acid ester polymer (A) obtained in the above step 1 (solid content conversion value; the same applies hereinafter), and a trimethylolpropane-modified trimethylolpropane-modified trimethylolpropane Diisocyanate (manufactured by Toyochem Co., Ltd., product name "BHS8515") 0.2 parts by mass, and polyethylene glycol # 400 dimethacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name "NK Ester A-9G") as (meth)acrylate (C1) ”, 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") 4 parts by mass, and a 1:1 (mass ratio) mixture of 1-hydroxy-cyclohexyl-phenyl-ketone and benzophenone as a photopolymerization initiator (D) (manufactured by BASF, product 0.7 parts by mass of the name "OMNIRAD 500") and 0.3 parts by mass of N-glycidoxypropyltrimethoxysilane as the silane coupling agent (E) are mixed, thoroughly 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) is 100 parts by mass (solid content conversion value). Details of abbreviations and the like in Table 1 are as follows.
[(Meth) acrylic 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”, weight average molecular weight of polyethylene glycol: 400)
C1-2: Polyethylene glycol #400 diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name “NK Ester A-400”, weight average molecular weight of polyethylene glycol: 400)
C1-3: Polyethylene glycol #600 diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name “NK Ester A-600”, weight average molecular weight of polyethylene glycol: 600)
PEG1000: Polyethylene glycol with a weight average molecular weight of 1000 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., product name "poly (ethylene glycol) 1000") (PEG1000 does not correspond to (meth)acrylate (C1), but for convenience ( Described in the column of meth) acrylate (C1).)
[Photoinitiator (D)]
D1: 1:1 (mass 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 adhesive sheet The coating solution of the adhesive composition obtained in the above step 2 is applied to a heavy release type release sheet (manufactured by Lintec Co., Ltd., product name "SP-PET752150") in which one side of a polyethylene terephthalate film is release treated with a silicone release agent. ”) was coated with a knife coater, followed by heat treatment at 80° C. for 1 minute and then at 110° C. for 1 minute to form a coating layer. A light release release sheet (manufactured by Lintec Corporation, product name "SP-PET381130 ”), and cured for 7 days under conditions of 23 ° C. and 50% RH to form a heavy release release sheet / active energy ray-curable adhesive layer (thickness: 50 μm) / A pressure-sensitive adhesive sheet having a configuration of a light-release type release sheet was produced.

The thickness of the pressure-sensitive adhesive layer is a value measured in accordance with JIS K7130 using a constant-pressure thickness gauge (manufactured by Teclock, product name: "PG-02").

[Examples 2 to 6, Comparative Examples 1 to 5]
Type and ratio of each monomer constituting the (meth)acrylic acid ester polymer (A), type and amount of (meth)acrylate (C1), 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 amount of (D) were changed as shown in Table 1.

Here, the weight-average molecular weight (Mw) described above is a polystyrene-equivalent weight-average molecular weight measured using gel permeation chromatography (GPC) under the following conditions (GPC measurement).
<Measurement conditions>
・ Measuring device: HLC-8320 manufactured by Tosoh Corporation
・ GPC column (passed in the following order): TSK gel superH-H manufactured by Tosoh Corporation
TSK gel super HM-H
TSK gel super H2000
・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 measured as a homopolymer of each monomer constituting the (meth)acrylic acid ester polymer (A). was calculated by the FOX formula based on the glass transition temperature (Tg) of Table 1 shows the results.

[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. By subtracting the individual mass, the mass of the adhesive alone was calculated. Let the mass at this time be M1.

Next, the adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23° C.) for 72 hours. After that, the pressure-sensitive adhesive was taken out and air-dried for 24 hours in an environment of a temperature of 23° C. and a relative humidity of 50%, and further dried in an oven of 80° C. for 12 hours. After drying, the mass was weighed with a precision balance, and the mass of the adhesive alone was calculated by subtracting the mass of the mesh alone. Let the mass at this time be M2. A gel fraction (%) is represented by (M2/M1)×100. From this, the gel fraction (before active energy ray (UV) irradiation) of the adhesive (active energy ray-curable adhesive) was derived. Table 2 shows the results.

On the other hand, the pressure-sensitive adhesive sheet obtained in Example 1 was irradiated with an active energy ray under the following conditions through a light release type release sheet to cure the pressure-sensitive adhesive layer to obtain a cured pressure-sensitive adhesive layer. In addition, the pressure-sensitive adhesive sheets obtained in Examples 2-6 and Comparative Examples 1-4 were coated with a plastic plate (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name "Iupilon Sheet MR58U", thickness: 1 mm, containing an ultraviolet absorber) were superimposed. Then, through the plastic plate, an active energy ray was irradiated under the following conditions to cure the adhesive layer to obtain a cured adhesive layer. The gel fraction (after irradiation with active energy rays (UV)) was derived in the same manner as described above for the adhesive of the obtained cured adhesive layer (cured adhesive). Table 2 shows the results.

<Active energy ray irradiation conditions>
・Using a high-pressure mercury lamp ・Illuminance 200mW/cm ² , Light intensity 1000mJ/cm ²
・Using “UVPF-A1” manufactured by Eye Graphics Co., Ltd. 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 under the same conditions as in Test Example 2 through a light release type release sheet to cure the pressure-sensitive adhesive layer to obtain a post-curing pressure-sensitive adhesive layer. In addition, the pressure-sensitive adhesive sheets obtained in Examples 2-6 and Comparative Examples 1-4 were coated with a plastic plate (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name "Iupilon Sheet MR58U", thickness: 1 mm, containing an ultraviolet absorber) were superimposed. Then, an active energy ray was irradiated through the plastic plate under the same conditions as in Test Example 2 to cure the adhesive layer to obtain a post-curing adhesive layer. The haze value (%) of the cured pressure-sensitive adhesive layer 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 which was not irradiated with active energy rays. Table 2 shows the results.

[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 coated with a polyethylene terephthalate (PET) film having an easy-adhesion layer (manufactured by Toyobo Co., Ltd., product name "PET A4300"). , thickness: 100 μm) to obtain a laminate of heavy release type release sheet/adhesive layer/PET film. The laminate thus obtained was cut to a width of 25 mm and a length of 100 mm.

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

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 obtain a post-curing pressure-sensitive adhesive layer. Further, in Examples 2 to 6 and Comparative Examples 1 to 4, a plastic plate (manufactured by Mitsubishi Gas Chemical Co., Ltd., product name "Iupilon Sheet MR58U", thickness: 1 mm, ultraviolet absorbent containing) were superimposed. Then, an active energy ray was irradiated through the plastic plate under the same conditions as in Test Example 2 to cure the adhesive layer to obtain a post-curing adhesive layer. In Comparative Example 5, the active energy ray was not irradiated.

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

[Test Example 5] (Measurement of step follow-up rate)
On the surface of a glass plate (manufactured by NSG Precision Co., Ltd., product name “Corning Glass Eagle XG”, length 90 mm × width 50 mm × thickness 0.5 mm), ultraviolet curable ink (manufactured by Teikoku Ink Co., Ltd., product name “POS-911 ink”) ) was screen-printed into a picture frame (outer shape: length 90 mm, width 50 mm, width 5 mm) with a predetermined thickness. Next, ultraviolet rays are irradiated (80 W/cm ² , 2 metal halide lamps, lamp height 15 cm, belt speed 10 to 15 m/min) to cure the printed UV curable ink, and the height of the step due to printing thickness: any one of 10 μm, 12.5 μm, 15 μm, 20 μm, 25 μm, 40 μm, 60 μm, 100 μm and 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 covered with a polyethylene terephthalate (PET) film having an easy-adhesion layer (manufactured by Toyobo Co., Ltd., product name "PET A4300", thickness: 100 μm). Next, peel off the heavy release type release sheet to expose the adhesive layer, and use a laminator (manufactured by Fujipla Co., Ltd., product name “LPD3214”) to make the adhesive layer cover the entire surface of the frame-shaped print. Laminated on a glass plate. After that, it was autoclaved for 20 minutes under the conditions of 50° C. and 0.5 MPa, and allowed to stand at normal pressure, 23° C. and 50% RH for 24 hours.

At this stage, the initial step followability was evaluated. The level difference followability is judged by whether or not the printing level difference is completely filled with the adhesive layer. judged to have failed to follow. The initial step conformability was evaluated as an initial step conformability rate (%) represented by the following formula. Table 2 shows the results.
Initial level difference follow-up rate (%) = {(height of level difference maintained in a buried state without air bubbles, floating, peeling, etc. (μm)) / (thickness of adhesive layer)} x 100

Next, in Example 1, an active energy ray was irradiated through the PET film under the same conditions as in Test Example 2 to cure the pressure-sensitive adhesive layer to obtain a post-curing pressure-sensitive adhesive layer. In Examples 2 to 6 and Comparative Examples 1 to 4, a plastic plate (manufactured by Mitsubishi Gas Chemical Co., Ltd., 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 irradiated through the plastic plate under the same conditions as in Test Example 2 to cure the adhesive layer to obtain a post-curing adhesive layer. In Comparative Example 5, the active energy ray was not irradiated.

Then, it was stored under high temperature and high humidity conditions of 85° C. and 85% RH for 72 hours (durability test), and thereafter, step followability (step followability after endurance test) was evaluated in the same manner as described above. The post-durability step followability was evaluated as the step follow-up rate (%) after the endurance shown by the following formula. Table 2 shows the results.
Level difference follow-up rate after endurance (%) = {(After endurance test, height of level difference maintained in a buried state without air bubbles, floating, peeling, etc. (μm)) / (thickness of adhesive layer after curing) }×100

[Test Example 6] (Evaluation of blister resistance)
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 adhered to the following plastic plate to obtain a pressure-sensitive adhesive layer-attached plastic plate.
(1) Polymethyl methacrylate resin (PMMA) plate (manufactured by Mitsubishi Gas Chemical Company, product name “Iupilon Sheet MR-200”, thickness: 0.7 mm, no ultraviolet absorber)
(2) A plastic plate in which a polymethyl methacrylate resin (PMMA) layer is laminated on a polycarbonate resin (PC) plate (manufactured by Mitsubishi Gas Chemical Company, product name “Iupilon Sheet MR58U”, thickness: 0.7 mm, UV absorber contained) (Adhesive layer is attached to the side of the polycarbonate resin plate)
(3) A plastic plate in which a polymethyl methacrylate resin (PMMA) layer is laminated on a polycarbonate resin (PC) plate (manufactured by Mitsubishi Gas Chemical Company, product name “Iupilon Sheet HMRS53T”, thickness: 2 mm, containing an ultraviolet absorber) (Adhesive layer is pasted on the side of the polycarbonate resin plate)

The heavy release type release sheet is peeled off from the plastic plate with the adhesive layer obtained above, and the plastic plate is attached to a soda lime glass plate (manufactured by Nippon Sheet Glass Co., Ltd.) with a size of 70 mm × 150 mm through the exposed adhesive layer. , thickness: 0.7 mm). Then, it was autoclaved for 20 minutes under the conditions of 50° C. and 0.5 MPa, and left at normal pressure, 23° C. and 50% RH for 24 hours.

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

Each sample was stored for 72 hours under high temperature and high humidity conditions of 85° C. and 85% RH. After curing, the state of the interface between the adhesive layer and the adherend (plastic plate, glass plate) was visually observed, and the blister resistance was evaluated according to the following criteria. In Comparative Example 5, blister resistance was evaluated in the same manner as described above, except that the active energy ray was not applied. Table 2 shows the results.
⊚: There were no air bubbles, floating or peeling in all 10 out of 10 samples.
Good: 9 to 7 out of 10 samples showed no air bubbles, no lifting or peeling.
Δ: 6 to 1 out of 10 samples showed no air bubbles, lifting or peeling.
x: Lifting and peeling occurred in all 10 samples.

[Test Example 7] (Evaluation of wet heat whitening resistance)
The pressure-sensitive adhesive layers of the pressure-sensitive adhesive sheets obtained in Examples and Comparative Examples are composed of a non-alkali glass plate (manufactured by Corning) having a thickness of 0.7 mm and a polymethyl methacrylate resin (PMMA) layer on a polycarbonate resin (PC) plate. was sandwiched between laminated plastic plates (manufactured by Mitsubishi Gas Chemical Company, product name “Iupilon Sheet HMRS53T”, thickness: 2 mm, containing ultraviolet absorber) to obtain a laminate.

The resulting laminate was autoclaved under conditions of 50° C. and 0.5 MPa for 30 minutes, and then allowed to stand at normal pressure, 23° C. and 50% RH for 24 hours. After that, the pressure-sensitive adhesive layer of the laminate was applied to the adhesive layer in Example 1 through the non-alkali glass plate, and in Examples 2 to 6 and Comparative Examples 1 to 4 through the plastic plate, under the same conditions as in Test Example 2. was irradiated with an active energy ray to cure the pressure-sensitive adhesive layer to form a cured pressure-sensitive adhesive layer. In addition, in Comparative Example 5, the active energy ray was not irradiated. The haze value (%) of this laminate (sample) was measured using a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., product name "NDH2000") according to JIS K7136:2000.

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

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. Table 2 shows the results. The pressure-sensitive adhesive sheet of Comparative Example 5 had unevenness due to phase separation of the pressure-sensitive adhesive layer (symbol * in the table).

As can be seen from Table 2, the cured pressure-sensitive adhesive layers formed using the pressure-sensitive adhesive sheets obtained in Examples are excellent in step followability and wet heat whitening resistance, as well as blister resistance and optical properties. was also excellent.

The pressure-sensitive adhesive sheet of the present invention can be suitably used, for example, in the production of a display, for laminating a stepped protective plate including a plastic plate and a desired display body constituent member.

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

Claims (9)

An adhesive composition containing an adhesive main agent and an active energy ray-curable component,
The adhesive main agent is a (meth)acrylic acid ester polymer (A),
The glass transition temperature (Tg) of the adhesive main agent is −25° C. or lower,
Adhesive containing, as the active energy ray-curable component, a bifunctional (meth)acrylate (C1) having a polyalkylene glycol skeleton and a trifunctional or higher (meth)acrylate (C2) having no polyalkylene glycol skeleton. preparing a pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer made of an active energy ray-curable pressure-sensitive adhesive obtained from a curable composition;
Producing a laminate obtained by laminating one display body constituent member and another display body constituent member via the adhesive layer of the adhesive sheet,
The pressure-sensitive adhesive layer of the laminate is irradiated with an active energy ray, and the pressure-sensitive adhesive layer is cured to form a cured pressure-sensitive adhesive layer.
A method of manufacturing a structure characterized by: The content of the bifunctional (meth)acrylate (C1) having a 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 main agent. 2. A method of manufacturing a structure according to claim 1, characterized in that: 3. The method for producing a structure according to claim 1 , wherein the adhesive composition contains a cross-linking agent (B). 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 with respect to 100 parts by mass of the (meth)acrylic acid ester polymer (A). 4. The method for manufacturing the structure according to any one of claims 1 to 3 , 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. A method for manufacturing the structure according to any one of claims 1 to 4 . 6. The method for manufacturing the structure according to any one of claims 1 to 5, wherein the adhesive has a gel fraction of 30% or more and 80% or less. 7. The method according to any one of claims 1 to 6, wherein the pressure-sensitive adhesive sheet comprises two release sheets and 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. A method of manufacturing a construct according to any one of the preceding claims. 8. The method according to claim 1 , wherein at least one of the one display body constituent member and the other display body constituent member has a step on at least the surface of the post-curing pressure-sensitive adhesive layer side. A method of making the described construct . 9. Production of the structure according to any one of claims 1 to 8, wherein the cured adhesive constituting the cured adhesive layer has a gel fraction of 50% or more and 95% or less. How .

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