KR20140118764A - Active energy ray-curable adhesive, adhesive sheet and laminate - Google Patents

Abstract

Provided are an active energy ray-curable adhesive which has excellent tracking properties to a gap by such a printed layer and also has excellent durability, an adhesive sheet, and a laminate. The active energy ray-curable adhesive is characterized by having a press-in stress of ten seconds after pressing in the surface of the adhesive layer in an area of 5mm×5mm with speed of 6mm/minute to depth of 500 micrometers, when the active energy ray-curable adhesive is an adhesive layer having thickness of 600 micrometers, to be 4.0-7.0 N before irradiating an active energy ray on the adhesive layer, and to be 7.0-15.0 N after irradiating the active energy ray on the adhesive layer, while the ratio of the press-in stress after irradiating the active energy ray on the adhesive layer for the press-in stress before irradiating the active energy ray on the adhesive ray is 1.30-2.50.

Description

ACTIVE ENERGY RAY-CURABLE ADHESIVE, ADHESIVE SHEET AND LAMINATE [0002]

The present invention relates to a pressure-sensitive adhesive sheet having an active energy ray-curable pressure-sensitive adhesive, an active energy ray-curable pressure-sensitive adhesive layer, and a laminate obtained by using the active energy ray-curable pressure-sensitive adhesive.

2. Description of the Related Art Various types of mobile electronic devices such as mobile phones and tablet terminals have a display using a display module having a liquid crystal element, a light emitting diode (LED element), and an organic electroluminescence (organic EL) element.

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

However, when the air gap, that is, the air layer exists, the reflection loss of light due to the difference in refractive index between the protective panel and the air layer and the refractive index difference between the air layer and the display module is large, and the display quality is deteriorated.

Thus, it has been proposed to improve the image quality of the display by filling the space between the protective panel and the display module with a pressure-sensitive adhesive layer. However, in the case of the display panel module side of the protective panel, the frame-shaped print layer may exist as a step. If the pressure-sensitive adhesive layer does not follow the step, the pressure-sensitive adhesive layer is lifted in the vicinity of the step, thereby causing reflection loss of light. For this reason, the pressure-sensitive adhesive layer is required to follow the step.

In order to solve the above problems, Patent Document 1 discloses a pressure-sensitive adhesive layer that fills the gap between a protective panel and a display module, wherein the shear storage modulus (G ') at 25 ° C and 1 Hz is 1.0 × 10 ⁵ Pa or less , And at the same time, a pressure-sensitive adhesive layer having a gel fraction of 40% or more.

Patent Document 2 discloses a transparent double-faced pressure-sensitive adhesive sheet for ultraviolet crosslinking which is obtained by ultraviolet crosslinking while retaining ultraviolet ray reactivity, and has an indentation hardness (C2 as Asker hardness) (a) in a range of 10 (C2 asuka hardness) (b) after secondary curing by ultraviolet irradiation is in the range of 33 (b)? 80.

Japanese Patent Application Laid-Open No. 2010-97070 Publication No. 2012-184423

In Patent Document 1, the storage elastic modulus at room temperature is lowered in the pressure-sensitive adhesive layer so as to improve the step-wise followability. However, if the storage elastic modulus at room temperature is lowered as described above, the storage elastic modulus at high temperature is lowered more than necessary, causing a problem under durability conditions. For example, there is a problem that bubbles are generated in the vicinity of the step when returning to normal temperature and normal humidity after the high temperature and high humidity conditions are performed.

Further, in Patent Document 2, the ratio between the press-in stress of the pressure-sensitive adhesive layer at the time of adherend application and the press-in stress of the pressure-sensitive adhesive layer after curing can not be made sufficiently large and the balance of step traceability and durability is insufficient. On the other hand, Patent Document 2 also evaluates uneven followability and foam resistance reliability (durability). However, the irregularity followability in Patent Document 2 is a followability to a spherical object called glass beads, which is easy to follow in comparison with a step having an angle equal to that of the print layer, and the durability evaluation is also performed in a very short duration test .

An object of the present invention is to provide an active energy ray-curable pressure-sensitive adhesive, pressure-sensitive adhesive sheet, and laminate excellent in durability and excellent followability to a step by a printed layer or the like.

In order to achieve the above object, first, the present invention is an active energy ray-curable pressure-sensitive adhesive which is cured by irradiation with an active energy ray, wherein when the active energy ray-curable pressure-sensitive adhesive is a pressure-sensitive adhesive layer having a thickness of 600 m, , The indentation stress 10 seconds after the indentation to a depth of 500 mu m at an area of 5 mm x 5 mm at a rate of 6 mm / min was 4.0 to 7.0 N before the active energy ray was applied to the pressure-sensitive adhesive layer, Wherein the ratio of the indentation stress after irradiating the active energy ray to the pressure sensitive adhesive layer with respect to the indentation stress before the application of the active energy ray to the pressure sensitive adhesive layer is from 7.0 to 15.0 N after irradiation with the active energy ray is from 1.30 to 2.50 (1). ≪ RTI ID = 0.0 > (1) < / RTI >

In the active energy ray-curable pressure-sensitive adhesive according to the invention (Invention 1), the indentation stress before the active energy ray irradiation and the indentation stress after irradiation with the active energy ray are defined as described above, Even after being left under the high temperature and high humidity conditions after the active energy ray irradiation, the step traceability is maintained, and bubbles are not generated and the durability is excellent.

In the above invention (Invention 1), the storage elastic modulus at 23 ° C of the active energy ray-curable pressure-sensitive adhesive is 0.01 to 0.2 MPa before the active energy ray-curable pressure-sensitive adhesive is irradiated with the active energy ray curable pressure- It is preferable that the pressure-sensitive adhesive is 0.02 to 0.5 MPa after irradiating the active energy ray (invention 2).

In the above invention (Invention 2), the ratio of the storage elastic modulus at 23 占 폚 after irradiating the active energy ray to the pressure-sensitive adhesive layer with respect to the storage elastic modulus at 23 占 폚 before the application of the active energy ray to the pressure- (Invention 3).

In the above inventions (inventions 1 to 3), the storage elastic modulus at 85 ° C of the active energy ray-curable pressure-sensitive adhesive is 0.01 to 0.1 MPa before the active energy ray-curable pressure-sensitive adhesive is irradiated with the active energy ray, After irradiating the active ray for the ray-curable pressure-sensitive adhesive, it is preferable that the pressure is 0.02 to 0.2 MPa (invention 4).

In the invention (Invention 4), the ratio of the storage elastic modulus at 85 캜 after irradiation of the active energy ray to the pressure-sensitive adhesive layer with respect to the storage elastic modulus at 85 캜 before irradiation of the active energy ray to the pressure-sensitive adhesive layer is 1.1 to 3.5 (Invention 5).

Secondly, the present invention provides a pressure-sensitive adhesive sheet comprising two release sheets and a pressure-sensitive adhesive layer sandwiched between the release sheets so as to contact with the release surfaces of the two release sheets, wherein the pressure-sensitive adhesive layer comprises the active energy ray- (Invention 1 to 5) (invention 6).

Thirdly, the present invention is a laminate comprising two hard plates and a pressure-sensitive adhesive layer for bonding the two hard plates together, wherein the pressure-sensitive adhesive layer comprises the active energy ray-curable pressure-sensitive adhesive (inventions 1 to 5) And curing it by irradiation of an energy ray (invention 7).

In the above invention (invention 7), it is preferable that at least one of the rigid plates has a step on the side of the pressure-sensitive adhesive layer side (invention 8).

In the invention (Invention 8), it is preferable that the step is a step by a print layer (Invention 9).

In the above inventions (inventions 7 to 9), at least one of the rigid plates may include a polarizing plate (invention 10).

In the above inventions (inventions 7 to 9), one of the two hard plates is a display module or a part thereof, and the other of the two hard plates has a frame-like step on the side of the pressure- It may be a protective plate (invention 11).

In the above invention (inventions 7 to 11), it is preferable that the total light transmittance of the pressure-sensitive adhesive layer is 80% or more (invention 12).

The pressure-sensitive adhesive layer of the active energy ray-curable pressure-sensitive adhesive according to the present invention and the pressure-sensitive adhesive sheet according to the present invention are excellent in step-following property before irradiation with active energy rays and excellent in durability after irradiation with active energy rays. In the layered product obtained by using such an active energy ray-curable pressure-sensitive adhesive, even if there is a step on the pressure-sensitive adhesive layer side, the pressure-sensitive adhesive layer follows the step, so that there is no lifting or bubbling in the vicinity of the step. Further, the pressure-sensitive adhesive layer of the laminate retains the step following property even when it is left under high-temperature and high-humidity conditions, so that bubbles and the like are not generated and the durability is excellent.

1 is a cross-sectional view of a pressure-sensitive adhesive sheet according to an embodiment of the present invention.
2 is a cross-sectional view of a laminate according to an embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described.

[Active energy ray-curable pressure-sensitive adhesive]

1. Properties

The active energy ray-curable pressure-sensitive adhesive according to the present embodiment has the following physical properties. In other words, when the active energy ray-curable pressure-sensitive adhesive according to the present embodiment was formed as a pressure-sensitive adhesive layer having a thickness of 600 μm, the surface of the pressure-sensitive adhesive layer was pressed 10 seconds after the pressure was applied to the area of 5 mm × 5 mm at a rate of 6 mm / Is 7.0 to 7.0 N before the active energy ray is irradiated to the pressure-sensitive adhesive layer, and 7.0 to 15.0 N after the active energy ray is irradiated to the pressure-sensitive adhesive layer.

The indentation stress in this specification was measured in the same manner as in Example 1 except that the pressure-sensitive adhesive layer had a size of 50 mm in length x 50 mm in width x 600 mm in thickness and the press-fitting member was a silicon chip having a size of 5 mm long x 5 mm wide x 500 mm thick, The test is carried out using a universal tensile compression tester (in the test example, "INSTRON 5581 type" manufactured by INSDORDO Co., Ltd.) under a relative humidity of 50% RH.

Since the indentation stress before the active energy ray irradiation is 4.0 to 7.0 N, the active energy ray curable pressure-sensitive adhesive has excellent step traceability at the time of application of the active energy ray before application. Therefore, even if there is a step on the adherend, the active energy ray-curable pressure-sensitive adhesive follows the step, and there is no lifting or bubbling in the vicinity of the step. If the indentation stress before the active energy ray irradiation is less than 4.0N, the workability of the cut or the like is lowered and the durability after irradiation with the active energy ray becomes insufficient. If the indentation stress before the active energy ray irradiation exceeds 7.0N, The followability is degraded. The indentation stress before the active energy ray irradiation is preferably 4.4 to 6.7 N, and more preferably 4.6 to 6.5 N.

On the other hand, since the indentation stress after the activation energy ray irradiation is in the range of 7.0 to 15.0 N, the active energy ray curable pressure-sensitive adhesive can be cured under high temperature and high humidity conditions (for example, 85 ° C and 85% RH for 240 hours) Even if left untreated, the step following property is maintained, and bubbles are not generated, and durability is excellent. If the indentation stress after irradiation with active energy rays is less than 7.0 N, the durability is deteriorated. If the indentation stress after irradiation with active energy rays exceeds 15.0 N, stepwise followability can not be maintained under high temperature and high humidity conditions. The indentation stress after irradiation with the active energy ray is preferably 7.2 to 11.0 N, particularly preferably 7.4 to 9.5 N.

The ratio of the indentation stress after the active energy ray irradiation to the indentation stress before the active energy ray irradiation (the indentation stress after irradiation with the active energy ray / the indentation stress before the activation energy ray irradiation) is 1.30 to 2.50, , And particularly preferably from 1.37 to 1.90. Since the ratio of the indentation stress is in the above range, the step following property before irradiation with active energy rays and the balance between durability after irradiation with active energy rays can be favorable.

The active energy ray-curable pressure-sensitive adhesive according to the present embodiment preferably has the following properties. In other words, the storage elastic modulus of the active energy ray-curable pressure-sensitive adhesive before irradiation with active energy rays is preferably 0.01 to 0.2 MPa, more preferably 0.04 to 0.15 MPa, further preferably 0.07 to 0.1 MPa desirable. The storage elastic modulus at 85 캜 of the active energy ray-curable pressure-sensitive adhesive before irradiation with active energy rays is preferably 0.01 to 0.1 MPa, more preferably 0.01 to 0.06 MPa, further preferably 0.02 to 0.04 MPa Do. Meanwhile, the storage elastic modulus in this specification is a value measured by a twist shear method at a measurement frequency of 1 Hz in accordance with JIS K7244-6. The active energy ray-curable pressure-sensitive adhesive before irradiation with active energy rays has a storage elastic modulus as described above, and is excellent in step-following ability.

On the other hand, the storage elastic modulus of the active energy ray-curable pressure-sensitive adhesive after irradiation with active energy rays is preferably 0.02 to 0.5 MPa, more preferably 0.05 to 0.3 MPa, further preferably 0.09 to 0.2 MPa Do. The storage elastic modulus at 85 캜 of the active energy ray-curable pressure-sensitive adhesive after irradiation with active energy rays is preferably 0.02 to 0.2 MPa, more preferably 0.02 to 0.1 MPa, further preferably 0.03 to 0.05 MPa Do. The active energy ray-curable pressure-sensitive adhesive after irradiation with active energy rays has a storage elastic modulus as described above, whereby it is excellent in durability.

Furthermore, the ratio of the storage elastic modulus at 23 占 폚 after the activation energy ray irradiation (the storage elastic modulus after irradiation with active energy rays / the storage elastic modulus before irradiation with active energy rays) relative to the storage elastic modulus at 23 占 폚 before irradiation with active energy rays, More preferably 1.2 to 2.0, and further preferably 1.3 to 1.7.

As described above, the storage elastic modulus of the active energy ray-curable pressure-sensitive adhesive at 23 DEG C is increased after irradiation of the active energy ray (after curing), whereby the cured active energy ray-curable pressure-sensitive adhesive has excellent durability.

The ratio of the storage elastic modulus at 85 占 폚 after the activation energy ray irradiation (storage elasticity ratio after irradiation with active energy rays / storage elasticity before irradiation with active energy rays) to storage elasticity at 85 占 폚 before irradiation with active energy rays was 1.1? More preferably 1.3 to 2.5, and further preferably 1.4 to 2.0.

As described above, the storage elastic modulus of the active energy ray-curable pressure-sensitive adhesive at 85 ° C is increased after irradiation of the active energy ray (after curing), so that the cured active energy ray-curable pressure-sensitive adhesive is excellent in durability even when left under high temperature.

If the ratio of the storage elastic modulus at 23 DEG C or 85 DEG C is less than 1.1, the durability improving effect as described above may not be obtained. On the other hand, if the ratio of the storage elastic modulus at 23 占 폚 exceeds 2.5 or the storage elastic modulus at 85 占 폚 exceeds 3.5, the adhesive force of the cured active energy ray-curable adhesive deteriorates and there is a fear that sufficient durability may not be obtained have. If the ratio of the storage elastic modulus at 23 占 폚 exceeds 2.5 or the storage elastic modulus at 85 占 폚 exceeds 3.5, the three-dimensional network structure formed by the activation energy ray curing becomes excessively dense, It may be deteriorated in wet heat resistance and heat resistance.

2. Materials

The active energy ray-curable pressure-sensitive adhesive (hereinafter sometimes simply referred to as "pressure-sensitive adhesive") according to the present embodiment may be made of any material as long as it satisfies the above-described physical properties and has desired adhesiveness and adhesiveness (Meth) acrylic acid ester copolymer (A) containing 5 to 20 mass% of (meth) acrylic acid as a monomer unit constituting the polymer, and an active energy ray curable component (B) having a weight average molecular weight of 200,000 to 900,000, ) And a cross-linking agent (C) (hereinafter sometimes referred to as " sticky composition P "). The active energy ray-curable pressure-sensitive adhesive obtained by thermally crosslinking the pressure-sensitive adhesive composition P is easy to satisfy the physical properties described above, and exhibits favorable tackiness and adhesiveness to hard plates and the like. In the present specification, (meth) acrylic acid means both acrylic acid and methacrylic acid. Other similar terms are also the same.

Specifically, the (meth) acrylic acid ester copolymer (A) is in a state of being crosslinked by the crosslinking agent (C) in the active energy ray-curable pressure-sensitive adhesive obtained by thermally crosslinking the adhesive composition P. On the other hand, the active energy ray-curable component (B) is not yet cured and is present in the active energy ray-curable pressure-sensitive adhesive in such a state that it is blended with the adhesive composition P. The active energy ray-curable component (B) undergoes polymerization curing when the active energy ray-curable pressure-sensitive adhesive is irradiated with an active energy ray at the time of use (when an adherend is attached).

(1) The (meth) acrylic acid ester copolymer (A)

The (meth) acrylic acid ester copolymer (A) preferably contains 5 to 20 mass%, particularly preferably 7 to 15 mass%, of (meth) acrylic acid as the monomer unit constituting the polymer, By mass to 8% by mass to 12% by mass. When the content of the (meth) acrylic acid is within the above range, the crosslinking structure formed by the (meth) acrylic acid ester copolymer (A) and the crosslinking agent (C) is satisfactory and the pressure-sensitive adhesive has durability. When the content of (meth) acrylic acid is within the above range, the cohesive force of the pressure sensitive adhesive can be improved, and the stress relaxation property can be improved while suppressing the weight average molecular weight and the crosslink density of the (meth) acrylic acid ester copolymer It is possible to improve the step-wise followability of the pressure-sensitive adhesive. Further, in the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition P containing the (meth) acrylic acid ester copolymer (A) having a content of (meth) acrylic acid within the above-mentioned range, 85 ° C and 85% RH for 240 hours), whitening at the time of returning to normal temperature and normal humidity is suppressed, that is, excellent resistance to moisture and heat is obtained. When the (meth) acrylic acid ester copolymer (A) contains (meth) acrylic acid in the above amount as a monomer unit, a predetermined amount of a carboxyl group remains in the obtained pressure sensitive adhesive (after thermal crosslinking). The carboxyl group is a hydrophilic group. When such a hydrophilic group is present in a predetermined amount of the pressure-sensitive adhesive, even if the pressure-sensitive adhesive is left under high temperature and high humidity conditions after irradiation with active energy rays, moisture penetrated into the pressure- It is presumed that the pressure-sensitive adhesive is likely to escape from the pressure-sensitive adhesive. As a result, whitening of the pressure-sensitive adhesive is suppressed.

If the content of (meth) acrylic acid as the monomer unit in the (meth) acrylic acid ester copolymer (A) is less than 5% by mass, the active energy ray curable pressure-sensitive adhesive may be inferior in wet heat- On the other hand, if the content of (meth) acrylic acid exceeds 20% by mass, the coating property of the adhesive composition P may deteriorate.

The (meth) acrylic acid ester copolymer (A) preferably contains a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as the monomer unit constituting the polymer, and is particularly preferably contained as a main component . As a result, the obtained pressure-sensitive adhesive can exhibit favorable tackiness.

Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl Stearyl (meth) acrylate, stearyl (meth) acrylate, and the like. Of these, (meth) acrylic acid esters having an alkyl group of 1 to 8 carbon atoms are preferable from the viewpoint of further improving the tackiness, and methyl (meth) acrylate, n-butyl (meth) acrylate and 2-ethylhexyl Is particularly preferable. On the other hand, these may be used alone, or two or more kinds may be used in combination.

The (meth) acrylic acid ester copolymer (A) preferably contains 40 to 95 mass% of a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as the monomer unit constituting the polymer, By mass to 93% by mass, and more preferably from 88 to 92% by mass.

The (meth) acrylic acid ester copolymer (A) may contain other monomer as a monomer unit constituting the polymer, if desired. As other monomers, monomers which do not contain a reactive functional group are preferable in order not to interfere with the action of (meth) acrylic acid. Examples of such other monomers include (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, (meth) acrylic acid having an aliphatic ring such as (meth) (Meth) acrylate having a non-crosslinkable tertiary amino group such as N, N-dimethylaminoethyl (meth) acrylate and N, N-dimethylaminopropyl (meth) acrylate Methacrylic acid esters, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

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

The weight average molecular weight of the (meth) acrylic acid ester copolymer (A) is preferably from 200,000 to 900,000, particularly preferably from 250,000 to 700,000, and more preferably from 300,000 to 500,000. On the other hand, the weight average molecular weight in the present specification is a value in terms of polystyrene measured by a gel permeation chromatography (GPC) method.

Since the weight average molecular weight of the (meth) acrylic acid ester copolymer (A), which is the main component of the sticky composition P, is relatively small as described above, the pressure sensitive adhesive obtained by thermally crosslinking the sticky composition P has excellent step traceability. If the weight-average molecular weight of the (meth) acrylic acid ester copolymer (A) exceeds 90,000, the stepwise followability may be inferior. On the other hand, when the weight average molecular weight of the (meth) acrylic acid ester copolymer (A) is less than 200,000, the pressure sensitive adhesive of active energy ray irradiation may be inferior in durability.

On the other hand, in the sticky composition P, the (meth) acrylic acid ester copolymer (A) may be used singly or in combination of two or more kinds.

(2) Active energy ray-curable component (B)

When the adhesive composition P contains the active energy ray-curable component (B), the resulting pressure-sensitive adhesive becomes an active energy ray-curable pressure-sensitive adhesive and has excellent step traceability and durability.

The active energy ray curable component (B) is not particularly limited as long as it is a component that does not interfere with the effect of the present invention and is cured by irradiation with active energy rays, and may be any of monomers, oligomers or polymers, good. Among them, polyfunctional acrylate-based monomers having a molecular weight of less than 1,000 and excellent in compatibility with the (meth) acrylic acid ester copolymer (A) and the like are preferable.

Examples of the polyfunctional acrylate monomer having a molecular weight of less than 1000 include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di , Neopentyl glycol adipate di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone denatured Bifunctional types such as dicyclopentenyl (meth) acrylate, ethylene oxide modified di (meth) acrylate, di (acryloxyethyl) isocyanurate and allylated cyclohexyldi Propane tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (Meth) acrylate modified with tris (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) isocyanurate, epsilon -caprolactone modified tris- Trifunctional types such as tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate; and pentafunctional types such as propionic acid-modified dipentaerythritol penta (meth) acrylate; di And hexafunctional types such as pentaerythritol hexa (meth) acrylate and caprolactone-modified dipentaerythritol hexa (meth) acrylate. These may be used singly or in combination of two or more kinds.

As the active energy ray-curable component (B), an acrylate-based oligomer of active energy ray-curable type may be used. The acrylate oligomer preferably has a weight average molecular weight of 50,000 or less. Examples of such acrylate oligomers include polyester acrylate, epoxy acrylate, urethane acrylate, polyether acrylate, polybutadiene acrylate, and silicone acrylate.

Here, the polyester acrylate oligomer can be produced, for example, by esterifying a hydroxyl group of a polyester oligomer having a hydroxyl group at both ends with condensation of a polyhydric alcohol and a polyhydric alcohol with (meth) acrylic acid, Can be obtained by esterifying a terminal hydroxyl group of an oligomer obtained by adding an alkylene oxide to a carboxylic acid with (meth) acrylic acid. The epoxy acrylate oligomer can be obtained, for example, by reacting (meth) acrylic acid with an oxirane ring of a relatively low molecular weight bisphenol-type epoxy resin or novolak-type epoxy resin to esterify it. An epoxy acrylate oligomer obtained by modifying the epoxy acrylate oligomer with a dibasic carboxylic acid anhydride in a carboxy modified form may also be used. The urethane acrylate oligomer can be obtained, for example, by esterifying a polyurethane oligomer obtained by a reaction of a polyether polyol or a polyester polyol with a polyisocyanate with (meth) acrylic acid. The polyol acrylate oligomer can be obtained by esterifying a hydroxyl group of a polyether polyol with (meth) acrylic acid.

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

As the active energy ray curable component (B), an acryl acrylate polymer having a group having a (meth) acryloyl group introduced into its side chain may also be used. Such an adduct acrylate-based polymer is obtained by using a copolymer of a (meth) acrylic acid ester and a monomer having a crosslinkable functional group in a molecule, and adding a (meth) acryloyl group and a crosslinking With a compound having a group reactive with a malfunctioning group.

The (meth) acrylic acid ester is preferably one containing an alkyl (meth) acrylate ester in which the alkyl group has 1 to 20 carbon atoms. Examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, (Meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl ) Dodecyl acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, and stearyl (meth) acrylate. These may be used alone or in combination of two or more.

The monomer having a crosslinkable functional group in the molecule preferably contains at least one kind selected from a hydroxyl group, a carboxyl group, an amino group and an amide group as a functional group. Examples of such monomers include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (Meth) acrylate such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylate; acrylamides such as N-methylolmethacrylamide; (Meth) acrylate monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate and monoethylaminopropyl (meth) And ethylenically unsaturated carboxylic acids such as acetic acid, crotonic acid, maleic acid, itaconic acid and citraconic acid. These monomers may be used alone or in combination of two or more.

Examples of the compound having a (meth) acryloyl group and a group capable of reacting with a crosslinkable functional group include 2-methacryloyloxyethyl isocyanate, 2- (0- [1'-methylpropylideneamino] (Bishydroxyethyl) ethyl isocyanate, 2-acryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, 2-acryloyloxyethylhexahydrophthalimide,? -Carboxy-polycaprolactone monoacrylate, phthalic acid monohydroxyethyl acrylate, 2-hydroxy-3- Phenoxy propyl acrylate, and the like. These compounds may be used alone or in combination of two or more.

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

The active energy ray curable component (B) may be selected from among the above-mentioned polyfunctional acrylate-based monomer, acrylate-based oligomer and adduct acrylate-based polymer, or a combination of two or more thereof , And other active energy ray-curable components.

The content of the active energy ray-curable component (B) in the adhesive composition P is preferably 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, per 100 parts by mass of the (meth) acrylic acid ester copolymer (A) And further preferably 3 to 7 parts by mass. If the content of the active energy ray-curable component (B) is less than 1 part by mass, there is a fear that the durability of the pressure-sensitive adhesive after irradiation with active energy rays is lowered. When the content of the active energy ray-curable component (B) exceeds 10 parts by mass, there is a possibility that the wettability of the pressure-sensitive adhesive after irradiation with active energy rays deteriorates.

(3) Crosslinking agent (C)

The adhesive composition P contains a crosslinking agent (C) to form a three-dimensional network structure by crosslinking the (meth) acrylic acid ester copolymer (A), thereby improving the cohesive force of the obtained pressure sensitive adhesive. Further, after the active energy ray irradiation, the pressure-sensitive adhesive may be provided with durability.

The cross-linking agent (C) is not particularly limited as long as it can react with a reactive group (a carboxy group of (meth) acrylic acid as a monomer unit) possessed by the (meth) acrylic acid ester copolymer (A). Examples thereof include isocyanate- An amine crosslinking agent, a melamine crosslinking agent, a melamine crosslinking agent, an aziridine crosslinking agent, a hydrazine crosslinking agent, an aldehyde crosslinking agent, an oxazoline crosslinking agent, a metal alkoxide crosslinking agent, a metal chelate compound crosslinking agent, a metal salt crosslinking agent and an ammonium salt crosslinking agent. The crosslinking agent (C) may be used singly or in combination of two or more kinds.

Among them, it is preferable to use at least one selected from an epoxy crosslinking agent and an isocyanate crosslinking agent excellent in reactivity with a carboxy group as a crosslinking agent (C), and it is particularly preferable to use an epoxy crosslinking agent. The pressure-sensitive adhesive using an epoxy-based crosslinking agent is excellent in heat resistance and does not change to yellow, so that it is suitable for optical use.

Examples of the epoxy cross-linking agent include 1,3-bis (N, N'-diglycidylaminomethyl) cyclohexane, N, N, N ', N'-tetraglycidyl- Ethylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylol propane diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like.

The isocyanate crosslinking agent includes at least a polyethylene isocyanate compound. Examples of the polyethylene isocyanate compound include aromatic polyethylene isocyanate such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyethylene isocyanate such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate Cyclic polyethylene isocyanate and the like, and their adducts, such as burettes, isocyanurates, and furthermore, reaction products of low-molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylol propane, And the like.

The content of the crosslinking agent (C) in the adhesive composition P is preferably 0.001 to 2 parts by mass, particularly preferably 0.01 to 1 part by mass, per 100 parts by mass of the (meth) acrylic acid ester copolymer (A) 0.02 to 0.3 parts by mass. When the content of the crosslinking agent (C) is 0.001 part by mass or more, the durability improving effect can be given to the pressure sensitive adhesive after irradiation with active energy rays. When the content of the cross-linking agent (C) exceeds 2 parts by mass, the degree of cross-linking becomes excessive, and there is a fear that the step-following property of the obtained pressure-sensitive adhesive is lowered. Further, a large amount of the carboxy group of the (meth) acrylic acid ester copolymer (A) reacts with the crosslinking agent (C), so that the amount of the carboxyl groups remaining in the pressure sensitive adhesive is reduced,

(4) Photopolymerization initiator (D)

When ultraviolet rays are used as an active energy ray to be irradiated on the active energy ray-curable pressure-sensitive adhesive, it is preferable that the pressure-sensitive adhesive composition P further contains a photopolymerization initiator (D). By containing the photopolymerization initiator (D) in this manner, the active energy ray curable component (B) can be efficiently cured, and the polymerization curing time and irradiation amount of the active energy ray can be reduced.

Examples of the photopolymerization initiator (D) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylamino 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxynaphthoic acid, 2-methoxy-2-phenylacetophenone, Methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 4- (2-hydroxyethoxy) phenyl- 2- 2-ethyl anthraquinone, 2-tertiary anthraquinone, 2-ethylhexanoic acid, 2-ethylhexanoic acid, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, , Benzyl dimethyl ketal, acetone (2-hydroxy-2-methyl-1- [4- (1-methylvinyl) phenyl] propanone], 2,4,6- trimethylbenzoyl- Phosphine oxide, and the like. These may be used alone or in combination of two or more.

The photopolymerization initiator (D) is preferably used in an amount of 2 to 15 parts by mass, particularly 4 to 12 parts by mass, based on 100 parts by mass of the active energy ray curable component (B).

(5) Various additives

The adhesive composition P is preferably added with various additives commonly used in acrylic pressure sensitive adhesives such as a silane coupling agent, an antistatic agent, a tackifier, an antioxidant, an ultraviolet absorber, a light stabilizer, a softener, a filler, can do.

The silane coupling agent is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule and having good water-miscibility with the (meth) acrylic acid ester copolymer (A). In addition, when the pressure-sensitive adhesive is for optical use, a silane coupling agent having optical transparency is preferable.

Examples of such silane coupling agents include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane , And silicon compounds having an epoxy structure such as 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -methyltrimethoxysilane, Amino group-containing silicon compounds such as 3-aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-isocyanatepropyltriethoxysilane or the like, and at least one of methyltriethoxysilane, ethyltriethoxysilane, Methyltrimethoxysilane, And condensation products with an alkyl group-containing silicon compound such as ethyltrimethoxysilane. These may be used singly or in combination of two or more kinds.

The addition amount of the silane coupling agent is preferably 0.01 to 1.0 part by mass, more preferably 0.05 to 0.5 part by mass with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A).

(6) Production of sticky composition

The adhesive composition P is obtained by preparing the (meth) acrylic ester copolymer (A), mixing the obtained (meth) acrylic acid ester copolymer (A), the active energy ray curable component (B) and the crosslinking agent , And optionally adding a photopolymerization initiator (D) and / or an additive.

The (meth) acrylic acid ester copolymer (A) can be produced by polymerizing a mixture of monomers constituting the polymer by a usual radical polymerization method. The polymerization of the (meth) acrylic acid ester copolymer (A) can be carried out by a solution polymerization method or the like using a polymerization initiator if desired. 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.

As the polymerization initiator, an azo compound, an organic peroxide and the like can be enumerated, and two or more kinds of them may be used in combination. Examples of the azo based compound include azo compounds such as 2,2'-azobisisobutylonitrile, 2,2'-azobis (2-methylbutylonitrile), 1,1'-azobis (cyclohexane 1-carbo Aziridine), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxy valeronitrile) Azobis (2-methylpropionate), 4,4'-azobis (4-cyanovaleric acid), 2,2'-azobis (2-hydroxymethylpropionitrile) Azobis [2- (2-imidazolin-2-yl) propane] and the like.

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

On the other hand, in the above-mentioned polymerization step, the weight average molecular weight of the obtained polymer can be controlled by blending a chain transfer agent such as 2-mercaptoethanol.

(B), a crosslinking agent (C) and, if desired, a polymerization initiator (D) are added to a solution of the (meth) acrylic acid ester copolymer (A) , And additives are added and sufficiently mixed to obtain a sticky composition P.

(7) Production of active energy ray-curable pressure-sensitive adhesive

The above adhesive composition P is applied and thermally crosslinked to obtain an active energy ray curable pressure-sensitive adhesive according to the present embodiment. Thermal crosslinking of the sticky composition P can be performed by heat treatment. This heat treatment may also be used in the drying treatment after the application of the adhesive composition P.

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

The (meth) acrylic acid ester copolymer (A) is crosslinked satisfactorily through the crosslinking agent (C) by the above heat treatment (and curing) to obtain an active energy ray curable pressure sensitive adhesive. On the other hand, in this active energy ray-curable pressure-sensitive adhesive, an active energy ray-curable component (B) is present in such state incorporated in the adhesive composition P.

The active energy ray-curable pressure-sensitive adhesive according to the present embodiment described above is excellent in step-following property before irradiation with active energy rays and has excellent durability after irradiation with active energy rays. Particularly, the active energy ray-curable pressure-sensitive adhesive obtained by thermally crosslinking the adhesive composition P is excellent in moisture absorption and heat-releasing property after irradiation with active energy rays.

[Adhesive sheet]

1, the pressure-sensitive adhesive sheet 1 according to the present embodiment includes two sheets of peelable sheets 12a and 12b and two sheets of peelable sheets 12a and 12b, And a pressure-sensitive adhesive layer 11 sandwiched between the release sheets 12a and 12b. On the other hand, in the present specification, the release surface of the release sheet means a surface having release properties in the release sheet, and includes both the surface subjected to the release treatment and the surface exhibiting the release property without performing the release treatment.

1. Adhesive layer

The pressure-sensitive adhesive layer 11 in the pressure-sensitive adhesive sheet 1 is composed of the above-mentioned active energy ray-curable pressure-sensitive adhesive, and exhibits stickiness before irradiation with active energy rays and exhibits adhesiveness when cured with active energy rays. The pressure-sensitive adhesive layer (11) is preferably constituted by thermally crosslinking the pressure-sensitive adhesive composition (P). In this case, the active energy ray-curable component (B) in the adhesive composition P is polymerized and cured by irradiation with active energy rays.

The thickness of the pressure-sensitive adhesive layer 11 (measured in accordance with JIS K7130) is preferably 50 to 400 m, more preferably 70 to 300 m, further preferably 90 to 250 m. On the other hand, the pressure-sensitive adhesive layer 11 may be formed as a single layer, or a plurality of layers may be laminated.

If the thickness of the pressure-sensitive adhesive layer 11 is less than 50 占 퐉, sufficient step traceability may not be obtained. If the thickness of the pressure-sensitive adhesive layer 11 exceeds 400 占 퐉, the workability may deteriorate.

2. Peeling sheet

Examples of the release sheets 12a and 12b include a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film, a polyvinyl chloride film, a vinyl chloride copolymer film, a polyethylene terephthalate film, (Meth) acrylic acid copolymer film, an ethylene / (meth) acrylic acid ester copolymer film, a polystyrene film, a polycarbonate film, a polypropylene film, A film, a polyimide film, a fluororesin film, or the like can be used. The crosslinked film may also be used. Further, these laminated films may be used.

It is preferable that a peeling treatment is performed on the peeling surface of the peeling sheets 12a and 12b (in particular, the surface in contact with the peeling layer 11). Examples of the releasing agent used in the peeling treatment include alkyd-based, silicone-based, fluorine-based, unsaturated polyester-based, polyolefin-based, and wax-based releasing agents. On the other hand, of the peeling sheets 12a and 12b, it is preferable that one peeling sheet is a heavy-duty peeling sheet having a large peeling force and the other peeling sheet is a light-duty peeling sheet having a small peeling force.

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

3. Production of adhesive sheet

As one example, a method for producing the pressure-sensitive adhesive sheet 1 using the adhesive composition P will be described.

As one production example of the adhesive sheet 1, the application liquid of the adhesive composition P is applied to the release surface of one of the release sheets 12a (or 12b) and the heat treatment is performed, And after the formation of the coating layer, the peeling surface of the other release sheet 12b (or 12a) is covered with the coating layer. When the curing period is required, the curing period is passed, and when the curing period is not necessary, the applied layer becomes the pressure-sensitive adhesive layer (11). Thus, the pressure-sensitive adhesive sheet (1) is obtained.

In another production example of the adhesive sheet 1, the application liquid of the adhesive composition P is applied to the release surface of one release sheet 12a, and heat treatment is performed to thermally crosslink the adhesive composition P to form a coating layer And a release sheet 12a with a coating layer is obtained. The application liquid 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, (12b). Then, the release sheet 12a with the application layer and the release sheet 12b with the application layer are bonded so that both of the application layers are in contact with each other. When the curing period is required, the curing period is exceeded, and when the curing period is unnecessary, the laminated coating layer becomes the pressure-sensitive adhesive layer (11). Thus, the pressure-sensitive adhesive sheet (1) is obtained.

As a method for applying the coating liquid of the viscous 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 and the like can be used. The conditions of the heat treatment for the applied sticky composition P are as described above.

In the above pressure-sensitive adhesive sheet 1, since the pressure-sensitive adhesive layer 11 before irradiation with the active energy ray is excellent in step-following property, even when there is a step in the adherend, voids or bubbles are generated between the step and the pressure- And the pressure-sensitive adhesive layer 11 can fill this step. Further, the pressure-sensitive adhesive layer 11 is excellent in durability by being cured by irradiation with active energy rays. Particularly, the pressure-sensitive adhesive layer (11) obtained by thermally crosslinking the adhesive composition (P) is also superior in wet heat resistance after irradiation with active energy rays.

The pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 according to the present embodiment is preferably used for bonding two hard plates together as described later.

[Laminate]

2, the laminate 2 according to the present embodiment includes a first rigid plate 21, a second rigid plate 22, and a first rigid plate 21 And a pressure-sensitive adhesive layer (11) for bonding the second hard plate (22) to each other. In the layered product 2 according to the present embodiment, the first rigid plate 21 has a step on the side of the pressure-sensitive adhesive layer 11, specifically, I have.

The first rigid plate 21 and the second rigid plate 22 are not particularly limited as long as they can adhere the pressure-sensitive adhesive layer 11. The first rigid plate 21 and the second rigid plate 22 may be made of the same material or different materials.

Examples of the first rigid plate 21 and the second rigid plate 22 include a laminated body such as a glass plate, a plastic plate, a metal plate and a semiconductor plate, a stacked body thereof, Plate-shaped hard products, and the like.

The glass plate is not particularly limited and includes, for example, a chemically strengthened glass, a non-alkali glass, a quartz glass, a soda lime glass, a glass containing barium and strontium, an aluminosilicate glass, a lead glass, a borosilicate glass, . The thickness of the glass plate is not particularly limited, but is usually 0.1 to 5 mm, preferably 0.2 to 2 mm.

The plastic plate is not particularly limited, and examples thereof include an acrylic plate and a polycarbonate plate. The thickness of the plastic plate is not particularly limited, but is usually 0.2 to 5 mm, preferably 0.4 to 3 mm.

On the other hand, various functional layers (a transparent conductive film, a metal layer, a silica layer, a hard coat layer, an antiglare layer or the like) may be provided on one or both sides of the glass plate or the plastic plate, or optical members may be laminated.

Examples of the optical member include a polarizing plate (polarizing film), a polarizer, a retardation film (phase difference film), a viewing angle compensating film, a luminance enhancing film, a contrast enhancing film, a liquid crystal polymer film, a diffusion film, a hard coat film, Film and the like.

Examples of the display module include a liquid crystal (LCD) module, a light emitting diode (LED) module, an electroluminescence (EL) module, and an electronic paper. On the other hand, the above-described glass plate, plastic plate (film), optical member and the like are usually laminated on these display body modules. For example, a polarizing plate is laminated on an LCD module, and the polarizing plate forms one surface of the LCD module.

It is preferable that at least one of the first rigid plate 21 and the second rigid plate 22 in the layered product 2 according to the embodiment contains a polarizing plate. The second rigid plate 22 in the layered product 2 according to the present embodiment is a display module or a part thereof (for example, an optical member such as a polarizing plate) , A glass plate, or the like. In this case, the print layer 3 is generally formed in a frame shape on the pressure-sensitive adhesive layer 11 side of the first rigid plate 21.

The material constituting the print 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 preferably 3 to 45 m, more preferably 5 to 35 m, further preferably 7 to 25 m, most preferably 7 to 15 m.

The thickness (step height) of the print layer 3 is preferably 3 to 30%, more preferably 3.2 to 20%, and further preferably 3.5 to 15% of the thickness of the pressure-sensitive adhesive layer 11 desirable. As a result, the pressure-sensitive adhesive layer 11 reliably follows the stepped portion by the printed layer 3, and no lifting or bubbling occurs near the stepped portion.

The pressure-sensitive adhesive layer 11 of the layered product 2 according to the present embodiment is obtained by laminating the pressure-sensitive adhesive layer made of the above-mentioned active energy ray-curable pressure-sensitive adhesive, preferably the pressure-sensitive adhesive layer 11 in the pressure- It is hardened by irradiation of energy ray. Herein, the term "active energy ray" means having an energy in an electromagnetic wave or a charged particle beam, specifically, ultraviolet rays, electron beams, and the like. Of the active energy rays, ultraviolet rays which are easy to handle are particularly preferable.

The irradiation of ultraviolet rays can be performed by a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, etc., and the irradiation dose of ultraviolet rays is preferably about 50 to 1,000 mW / cm ² . In addition, the amount of light, 50~10000mJ / cm ² is not preferable, and it is particularly preferred that 80~5000mJ / cm ² is more preferred, and 200~2000mJ / cm ² to. On the other hand, the irradiation of the electron beam can be performed by an electron beam accelerator or the like, and the irradiation amount of the electron beam is preferably about 10 to 1000 krad.

When the active energy ray is irradiated to the pressure-sensitive adhesive layer 11 obtained by thermally crosslinking the adhesive composition P, the active energy ray-curable component (B) is polymerized and cured. The pressure-sensitive adhesive layer 11, which is cured by irradiation of an active energy ray, is excellent in durability and excellent in moisture and heat resistance.

In order to produce the laminate 2, the one-side peeling sheet 12a (or 12b) of the pressure-sensitive adhesive sheet 1 is first peeled off as an example and the pressure-sensitive adhesive layer 1 (11) and the first rigid plate (21) (or the second rigid plate (22)). Then the other release sheet 12b (or 12a) is peeled off from the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1 and the exposed pressure-sensitive adhesive layer 11 of the pressure- The plate 22 (or the first rigid plate 21) is joined.

The pressure sensitive adhesive layer 11 has excellent step traceability when the pressure sensitive adhesive layer 11 and the first rigid plate 21 are bonded to each other in the above process so that the pressure difference between the stepped portion by the printing layer 3 and the pressure sensitive adhesive layer 11 No gap is generated in the pressure-sensitive adhesive layer 11, and the pressure-sensitive adhesive layer 11 can fill the step.

Thereafter, the pressure sensitive adhesive layer 11 is irradiated with an active energy ray at either the first rigid plate 21 or the second rigid plate 22 to cure the pressure sensitive adhesive layer 11. [ At this time, the hard plate on the side to irradiate the active energy ray needs to be active energy ray transmissive.

In the layered product 2 described above, since the pressure-sensitive adhesive layer 11 before irradiation with the active energy rays is excellent in step-following ability, voids or bubbles are not generated between the stepped portion by the print layer 3 and the pressure- . Further, even when the pressure-sensitive adhesive layer 11 cured by irradiation of an active energy ray is subjected to high-temperature and high-humidity conditions (for example, at 85 ° C and 85% RH for 240 hours), the step-following ability is maintained, And the like are prevented from being generated, and the durability is excellent. Furthermore, the pressure-sensitive adhesive layer 11 obtained by thermally crosslinking the pressure-sensitive adhesive composition P is cured by irradiating with an active energy ray because the whitening at the time of returning to normal temperature after the high temperature and high humidity condition is suppressed is suppressed, .

The excellent resistance to moisture and heat decomposition of the pressure-sensitive adhesive layer 11 cured by irradiation with active energy rays can be evaluated as follows. For example, both sides of the pressure-sensitive adhesive layer 11 are sandwiched between two alkali-free glass plates having a thickness of 1.1 mm, and the above-mentioned active energy rays of the illuminance and the light quantity are irradiated on at least one side of the glass- To obtain a laminate. This laminate is stored for 240 hours under the conditions of 85 ° C and 85% RH (wet heat conditions), and then taken out under normal temperature and normal humidity at 23 ° C and 50% RH. At this time, it is confirmed that the degree of whitening of the pressure-sensitive adhesive layer 11 is small.

The degree of whitening may be quantitatively evaluated by the haze value. Specifically, the value obtained by subtracting the haze value (%) before the wet condition from the haze value (%) after the wet heat condition in the laminate (the value measured in accordance with JIS K7136: 2000, hereinafter the same) ). ≪ / RTI > The rise in haze value after the moist heat condition is preferably less than 5.0 points, and particularly preferably less than 1.0 point. On the other hand, in the above evaluation, as the alkali-free glass, it is preferable to use a glass having a haze value of approximately 0%. The haze value of the pressure-sensitive adhesive layer after the moist heat condition is preferably 1.0% or less, more preferably 0.9% or less, further preferably 0.8% or less.

The pressure-sensitive adhesive layer 11 preferably has a total light transmittance (measured in accordance with JIS K7361-1: 1997) of preferably 80% or more, more preferably 90% or more, further preferably 99% or more . When the total light transmittance is 80% or more, transparency is high and it is favorable for optical use. Such a total light transmittance becomes easy to achieve by using an epoxy cross-linking agent which does not cause yellowing of the pressure-sensitive adhesive layer 11 as the cross-linking agent (C). On the other hand, the total light transmittance of the pressure-sensitive adhesive layer 11 does not substantially change before and after irradiation of the active energy rays.

The embodiments described above are described for the purpose of facilitating understanding of the present invention and are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design modifications and equivalents falling within the technical scope of the present invention.

For example, either one of the release sheets 12a and 12b in the adhesive sheet 1 may be omitted. Further, the first rigid plate 21 may have a step difference other than the print layer 3, or may not have a step difference. Further, not only the first rigid plate 21 but also the second rigid plate 22 may have a step on the pressure-sensitive adhesive layer 11 side.

Hereinafter, 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) acrylic acid ester copolymer

A reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen inlet tube was charged with 90 parts by mass of n-butyl acrylate, 10 parts by mass of acrylic acid, 200 parts by mass of ethyl acetate and 2,2'-azobisisobutyronitrile And 0.18 parts by mass of the reaction vessel were replaced with nitrogen gas. While stirring in the nitrogen atmosphere, the reaction solution was heated to 60 占 폚, allowed to react for 16 hours, and then cooled to room temperature. Here, a part of the obtained solution was measured for its molecular weight by the method described below, and the production of the (meth) acrylic acid ester copolymer (A) having a weight average molecular weight of 400,000 was confirmed.

2. Preparation of adhesive composition

100 parts by mass of the (meth) acrylic acid ester copolymer (A) obtained in the above step (1) (solid content conversion value; hereinafter the same) and polyethylene glycol diacrylate (manufactured by Shin Nakamura Kagaku Co., , 5 parts by mass of a polyvinyl alcohol (trade name: NK Ester A-400, solids concentration: 100% by mass) and 1, 3-bis 0.06 parts by mass of a silane coupling agent (product name: "TETRAD-C" manufactured by Sekigaku Corporation, solid content concentration: 100% by mass) and 3-glycidoxypropyltrimethoxysilane (product name: KBM -403 ") and 0.25 parts by mass of 1-hydroxycyclohexyl phenyl ketone (product name:" Ilgacure 184 "manufactured by BASF) as a photopolymerization initiator (D) diluted with methyl ethyl ketone to a solid concentration of 50% by mass Mixed, sufficiently stirred, and diluted with methyl ethyl ketone, To obtain a coating solution of a sticky composition having a solid content concentration of 39% by mass.

Table 1 shows the blend of the adhesive composition. The details of the abbreviations, etc. shown in Table 1 are the same as the following.

[(Meth) acrylic acid ester copolymer]

BA: n-butyl acrylate

AA: Acrylic acid

[Crosslinking agent]

Epoxy: 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane (product name: "TETRAD-C" manufactured by Mitsubishi Gas Chemical Company)

Isocyanate: Trimethylolpropane-modified tolylene diisocyanate (product name: Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.)

3. Production of adhesive sheet

The coating solution of the obtained sticky composition was applied to the release treatment surface of a heavy-duty release sheet (Lintec Co., Ltd., product name " SP-PET752150 ") in which one side of the polyethylene terephthalate film was stripped with a silicone- Coated with a coater, and then heat-treated at 100 DEG C for 4 minutes to form a coated layer. Likewise, the coating solution of the same sticking composition was applied to the release treatment surface of a light-receding type release sheet (trade name: SP-PET382120, manufactured by LINTEC CO., LTD.) In which one surface of a polyethylene terephthalate film was treated with a silicone- Coated with a knife coater, and then heat-treated at 100 DEG C for 4 minutes to form a coated layer.

Next, the heavy-duty release sheet with the coating layer thus obtained, and the light-weighted releasing sheet with the coating layer obtained as described above were bonded together so that both of the coating layers were in contact with each other, By curing, a pressure-sensitive adhesive sheet having a configuration of a heavy-duty releasing sheet / pressure-sensitive adhesive layer (thickness: 200 m) / light-duty releasing sheet was produced. On the other hand, the thickness of the pressure-sensitive adhesive layer is a value measured using a static pressure thickness gauge (product name: " PG-02 " manufactured by Teclock Co., Ltd.) in accordance with JIS K7130.

[Examples 2 to 8 and Comparative Examples 1 to 3]

(A), the kind and amount of the active energy ray-curable component (B), the amount of the cross-linking agent (C), the amount of the cross-linking agent (C) Sensitive adhesive sheet was produced in the same manner as in Example 1, except that the type and amount of the photopolymerization initiator (D), the blending amount of the photopolymerization initiator (D), the amount of the silane coupling agent and the thickness of the pressure-sensitive adhesive layer were changed as shown in Table 1. On the other hand, in Example 2, a pressure-sensitive adhesive sheet was produced in which the thickness of each coating layer in each of the heavy-weight release sheet with a coating layer and the light-weight releasable release sheet with a coating layer was 75 m, and the thickness of the pressure- In Example 7, ε-caprolactone modified tris- (2-acryloxyethyl) isocyanurate (product name: "NK Ester A-9300-" manufactured by Shin Nakamura Kagaku Co., Ltd.) was used as the active energy ray- (Trade name: " NK Ester A-TMM-3L ", trade name; available from Shin-Nakamura Chemical Co., Ltd.) as the active energy ray curable component (B) Quot ;, triester: 55% by mass, solid content: 100% by mass) was used.

Here, the weight average molecular weight (Mw) described above is a weight average molecular weight in terms of polystyrene measured by gel permeation chromatography (GPC) under the following conditions (GPC measurement).

<Measurement Conditions>

· GPC measuring apparatus: HLC-8020 manufactured by Tosoh Corporation

GPC column (passed in the following order): Toso Co., Ltd.

  TSK guard column HXL-H

  TSK gel GMHXL (× 2)

  TSK gel G2000 HXL

Measurement solvent: tetrahydrofuran

· Measuring temperature: 40 ℃

[Test Example 1] (Measurement of indentation stress)

The lightly curled releasing peel sheet and the heavy peel releasing sheet were peeled off from the pressure-sensitive adhesive sheet obtained in the example or the comparative example, and a plurality of pressure-sensitive adhesive layers were laminated so as to have a thickness of 600 mu m. The laminate of the pressure-sensitive adhesive layer thus obtained was cut into a length of 50 mm and a width of 50 mm, and this was used as a sample (sample before ultraviolet irradiation).

On the other hand, a silicon chip having a size of 5 mm in length × 5 mm in width × 600 μm in thickness obtained by dicing from a silicon wafer was prepared. The silicon chip was placed in a substantially central portion of the surface of the sample under a temperature of 23 DEG C and a relative humidity of 50% RH and the silicon chip was placed in a test tube using a universal tensile compression tester (product name: INSTRON 5581, The sample was pushed to a depth of 500 mu m at a speed of 6 mm / min, stopped in that state, and the indentation stress (N) after 10 seconds from the presser was measured.

The sample as described above was irradiated with ultraviolet rays under the following conditions by an ultraviolet ray irradiation apparatus (manufactured by Eyegraphics, product name: "IGranti ECS-401GX type") to cure the pressure-sensitive adhesive layer, . The indentation stress (N) was measured with respect to the sample after irradiation with ultraviolet rays as in the sample before ultraviolet irradiation.

[UV irradiation condition]

· Light source: High pressure mercury lamp

Light quantity: 1000 mJ / cm ²

Illumination: 200 mW / cm ²

From the measurement results, the ratio of indentation stress after ultraviolet irradiation (indentation stress after ultraviolet irradiation / indentation stress before ultraviolet irradiation) with respect to indentation stress before ultraviolet irradiation was calculated. The measurement results and the calculation results thereof are shown in Table 2.

[Test Example 2]

(Measurement of storage elastic modulus)

The lightly curled releasing peel sheet and the heavy peel releasing sheet were peeled off from the pressure-sensitive adhesive sheet obtained in the Example or Comparative Example, and a plurality of the pressure-sensitive adhesive layer were laminated so as to have a thickness of 0.6 mm. A cylinder (height: 0.6 mm) having a diameter of 8 mm was punched out from the laminate of the obtained pressure-sensitive adhesive layer to obtain a sample (sample before ultraviolet irradiation).

With respect to the sample, the storage elastic modulus (MPa) was measured according to JIS K7244-6 by a torsion shear method using a tackiness measuring apparatus (product name "MCR300" manufactured by Physica) under the following conditions.

Measuring frequency: 1Hz

Measuring temperature: 23 ° C, 85 ° C

The sample as described above was irradiated with ultraviolet rays under the following conditions by an ultraviolet irradiator (manufactured by Igraphics Co., Ltd., trade name &quot; Eye Granti ECS-401GX type &quot;) to cure the pressure- . The obtained sample after irradiation with ultraviolet rays was measured in the same manner as the sample before irradiation with ultraviolet rays, and the storage elastic modulus (MPa) was measured.

[UV irradiation condition]

· Light source: High pressure mercury lamp

Light quantity: 1000 mJ / cm ²

Illumination: 200 mW / cm ²

From the measurement results, the ratio of the storage elastic modulus after ultraviolet irradiation (storage elastic modulus after irradiation with ultraviolet light / storage elastic modulus before ultraviolet irradiation) with respect to the storage elastic modulus before irradiation with ultraviolet light at 23 占 폚 and 85 占 폚 was calculated. The measurement results and the calculation results thereof are shown in Table 2.

Test Example 3 (Evaluation of heat and humidity whitening)

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet obtained in Examples or Comparative Examples was sandwiched between two alkali-free glasses having a thickness of 1.1 mm and irradiated with ultraviolet rays under the ultraviolet irradiation conditions of Test Example 1 on one side of the glass to obtain a laminate. The haze value (%) of the laminate was measured according to JIS K7136: 2000 using a haze meter (product name: "NDH2000" manufactured by Nippon Denshoku Kogyo Co., Ltd.).

Next, the laminate was stored under the moist heat condition of 85 ° C and 85% RH for 240 hours. Then, the haze value (%) was measured according to JIS K7136: 2000 using a haze meter (product name: "NDH2000" manufactured by Nippon Denshoku Kogyo Co., Ltd.) Were measured. On the other hand, the haze value was measured within 30 minutes after returning the laminate to ordinary temperature and normal humidity.

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 rise in haze value after the wet heat condition. The haze value increase after the humid condition was less than 1.0 point was evaluated as wettability improvement (∘), the haze value increase after the humid condition was 1.0 point or more and less than 5.0 point in the wet heat whitening suitability value (?), The rise of 5.0 points or more was evaluated as wettability and whitening resistance (X). The results are shown in Table 2.

[Test Example 4] (Step following ability, durability test)

(a) Preparation of sample for evaluation

(Trade name: POS-911, manufactured by Teikoku Ink Co., Ltd.) was applied onto the surface of a glass plate (manufactured by NSG Precision Inc., product name "Coated Glass Eagle XG", length 90 mm x width 50 mm x thickness 0.5 mm) (Screen shape: 90 mm in length × 50 mm in width and 5 mm in width) so that the coating thickness was 8 μm and 15 μm. Then, the printed ultraviolet curable ink was cured by irradiating ultraviolet light (80 W / cm ² , metal halide lamp 2, lamp height 15 cm, belt speed 10 to 15 m / min) Height: 8 占 퐉 and 15 占 퐉).

The pressure-sensitive adhesive sheet obtained in the Example or Comparative Example was cut into a shape of 90 mm in length and 50 mm in width, and the lightly curled release sheet was removed to expose the pressure-sensitive adhesive layer. The pressure sensitive adhesive sheet was laminated on the stepped glass plate so that the pressure sensitive adhesive layer covers the printing face of the frame shape using a laminator (Fuji Plastic Co., product name "LPD3214").

Thereafter, the following evaluation samples (1) and (2) were prepared, respectively.

(1) After the lamination, the heavy-duty release sheet was peeled off and a glass plate (product name "Coated Glass Eagle XG", product name: "Coated Glass Eagle XG", length 90 mm × width 50 mm × thickness 0.5 mm) was laminated on the surface of the exposed pressure- To prepare an evaluation sample.

(2) A rigid plate laminated with a polarizer on a glass plate (made by NSG Precision, product name &quot; Coated Glass Eagle XG &quot;, length 90 mm x width 50 mm x thickness 0.5 mm) The intermediate peelable release sheet of the laminated adhesive sheet was peeled off from the stepped glass plate obtained in the above step and both were laminated with the laminator so that the exposed pressure-sensitive adhesive layer side and the polarizing plate side of the hard plate were in contact with each other, A sample was prepared.

(b) Evaluation of Step Followability (Initial)

The obtained evaluation samples (1) and (2) were pressurized at 0.5 MPa and 50 캜 for 30 minutes in an autoclave made by Kurarasa Seisakusho. Thereafter, whether or not bubbles were present in the pressure-sensitive adhesive layer (particularly in the vicinity of the step difference due to the print layer) was visually confirmed. Those without air bubbles were evaluated as initial step following suitability (?) And those with air bubbles as initial step following suitability defects (占). The results are shown in Table 2.

(c) Evaluation of durability (step followability after durability)

Next, the samples for evaluation (1) and (2) were stored for 240 hours under the conditions of 85 ° C and 85% RH. Thereafter, whether or not bubbles were present in the pressure-sensitive adhesive layer (particularly in the vicinity of the step difference due to the print layer) was visually confirmed. The durability (step following performance after durability) was evaluated as good (?) And the bubble was evaluated as durability (step following durability) and poor (x). The results are shown in Table 2.

[Test Example 5] (Total light transmittance measurement)

The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet obtained in Examples or Comparative Examples was applied to a glass, which was used as a sample for measurement. After measuring the background with a glass, the total light transmittance (%) of the measurement sample was measured using a haze meter (NDH-2000, manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with JIS K7361-1: 1997. The results are shown in Table 2.

As can be seen from Table 2, the pressure-sensitive adhesive layer obtained in the Examples was excellent in step-following property before irradiation with ultraviolet rays, excellent in durability after ultraviolet irradiation, and also excellent in resistance to moisture and heat.

The pressure-sensitive adhesive sheet of the present invention can be suitably used, for example, for bonding a display body module and a protective plate having a step difference.

One… Adhesive sheet
11 ... The pressure-
12a, 12b ... Peeling sheet
2… The laminate
21 ... The first rigid plate
22 ... The second rigid plate
3 ... Printing layer

Claims (12)

As an active energy ray-curable pressure-sensitive adhesive which is cured by irradiation of an active energy ray,
When the active energy ray-curable pressure-sensitive adhesive is a pressure-sensitive adhesive layer having a thickness of 600 탆,
The indentation stress after ten seconds after the surface of the pressure-sensitive adhesive layer was pressed down to a depth of 500 mu m at an area of 5 mm x 5 mm at a rate of 6 mm /
Before the active energy ray is irradiated to the pressure-sensitive adhesive layer, the pressure-sensitive adhesive layer is preferably 4.0 to 7.0 N,
After the active energy ray is irradiated to the pressure-sensitive adhesive layer, it is 7.0 to 15.0 N,
Wherein the ratio of the indentation stress after irradiation of the active energy ray to the pressure-sensitive adhesive layer with respect to the indentation stress before the application of the active energy ray to the pressure-sensitive adhesive layer is from 1.30 to 2.50. The method according to claim 1,
The storage elastic modulus of the active energy ray-curable pressure-
The active energy ray-curable pressure-sensitive adhesive is applied with 0.01 to 0.2 MPa before irradiation with active energy rays,
Characterized in that the active energy ray-curable pressure-sensitive adhesive is irradiated with an active energy ray and then is 0.02 to 0.5 MPa. The method of claim 2,
Wherein the ratio of the storage elastic modulus at 23 占 폚 after irradiating the active energy ray to the pressure sensitive adhesive layer with respect to the storage elastic modulus at 23 占 폚 before irradiation of the active energy ray to the pressure sensitive adhesive layer is 1.1 to 2.5. Curable adhesive. The method according to claim 1,
The storage elastic modulus of the active energy ray-curable pressure-
The active energy ray-curable pressure-sensitive adhesive is preferably applied in an amount of 0.01 to 0.1 MPa,
Characterized in that the active energy ray-curable pressure-sensitive adhesive is irradiated with an active energy ray and has a pressure of 0.02 to 0.2 MPa. The method of claim 4,
Wherein the ratio of the storage elastic modulus at 85 캜 after irradiation of the active energy ray to the pressure sensitive adhesive layer with respect to the storage elastic modulus at 85 캜 before irradiation of the active energy ray to the pressure sensitive adhesive layer is 1.1 to 3.5. Curable adhesive. Two release sheets,
And a pressure-sensitive adhesive layer sandwiched between the release sheets so as to come into contact with the release surfaces of the two release sheets,
Wherein the pressure-sensitive adhesive layer comprises the active energy ray-curable pressure-sensitive adhesive according to any one of claims 1 to 5. Two hard plates,
And a pressure-sensitive adhesive layer for bonding the two hard plates together,
Wherein the pressure-sensitive adhesive layer is obtained by curing the active energy ray-curable pressure-sensitive adhesive according to any one of claims 1 to 5 by irradiation with active energy rays. The method of claim 7,
Wherein at least one of the rigid plates has a step on the side of the pressure-sensitive adhesive layer side. The method of claim 8,
Wherein the step is a step by a print layer. The method of claim 7,
Characterized in that at least one of the rigid plates comprises a polarizing plate. The method of claim 7,
One of the two rigid boards is a display body module or a part thereof,
And the other of the two rigid plates is a protective plate having a stepped frame shape on the side of the pressure-sensitive adhesive layer side. The method of claim 7,
Wherein the pressure-sensitive adhesive layer has a total light transmittance of 80% or more.

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