JP2018131627A - Active energy ray-curable adhesive, adhesive sheet and laminate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an active energy ray-curable adhesive, an adhesive sheet and a laminate excellent in followability to a step formed of a print layer or the like, as well as excellent in durability.SOLUTION: The active energy ray-curable adhesive has such properties that: when the active energy ray-curable adhesive is formed into an adhesive layer having a thickness of 600 μm, an indentation stress 10 seconds after the surface of the adhesive layer is dented in a 5 (mm)×5 (mm) area at a velocity of 6 mm/min to a depth of 500 μm is 4.0 to 7.0 N before the adhesive layer is irradiated with active energy rays, and the indentation stress is 7.0 to 15.0 N after the adhesive layer is irradiated with active energy rays; and a ratio of the indentation stress after the adhesive layer is irradiated with active energy rays to the indentation stress before the adhesive layer is irradiated with active energy rays is 1.30 to 2.50.SELECTED DRAWING: Figure 1

Description

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

  Various mobile electronic devices such as mobile phones and tablet terminals in recent years include a display using a display module having a liquid crystal element, a light emitting diode (LED element), an organic electroluminescence (organic EL) element, and the like.

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

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

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

In order to solve the above-described problem, Patent Document 1 discloses that the shear storage elastic modulus (G ′) at 25 ° C. and 1 Hz is 1.0 as an adhesive layer that fills the gap between the protective panel and the display module. × is at 10 5 ^Pa or less, and a gel fraction discloses a pressure-sensitive adhesive layer is 40% or more.

  Further, Patent Document 2 is a transparent double-sided pressure-sensitive adhesive sheet for ultraviolet crosslinking which is ultraviolet-cured while leaving ultraviolet reactivity, and the indentation hardness (C2 Asker hardness) (a) is in the range of 10 ≦ (a) <50. The indentation hardness (C2 Asker hardness) (b) after secondary curing by further ultraviolet irradiation is disclosed in the range of 33 ≦ (b) ≦ 80.

JP 2010-97070 A JP 2012-184423 A

  In patent document 1, it is going to improve level | step difference followability by making low the storage elastic modulus at the time of normal temperature in an adhesive layer. However, when the storage elastic modulus at normal temperature is lowered as described above, the storage elastic modulus at high temperature is unnecessarily lowered, causing a problem under durability conditions. For example, there is a problem that bubbles are generated in the vicinity of a step when the temperature is returned to room temperature and humidity after high temperature and high humidity conditions are applied.

  Moreover, in patent document 2, the ratio of the indentation stress of the adhesive layer at the time of sticking an adherend and the indentation stress of the adhesive layer after hardening cannot be made large enough, and both level | step difference followability and durability are compatible. It was insufficient. Patent Document 2 also evaluates unevenness followability and foaming reliability (durability). However, the unevenness followability in Patent Document 2 is the ability to follow a spherical object called glass beads, and is easier to follow compared to a step having a corner like a printed layer, and the durability evaluation is also very high. In a short time endurance test.

  The present invention has been made in view of such a situation, and has an active energy ray-curable pressure-sensitive adhesive, a pressure-sensitive adhesive sheet, and a laminate excellent in followability to a step due to a printed layer and the like, and excellent in durability. The purpose is to provide.

  In order to achieve the above object, first, the present invention provides an active energy ray-curable pressure-sensitive adhesive that is cured by irradiation with active energy rays, the active energy ray-curable pressure-sensitive adhesive comprising a pressure-sensitive adhesive layer having a thickness of 600 μm. When the surface of the pressure-sensitive adhesive layer is pushed into the depth of 500 μm at a speed of 6 mm / min in an area of 5 mm × 5 mm, the indentation stress irradiates the pressure-sensitive adhesive layer with active energy rays. It is 4.0-7.0N before performing, and after irradiating an active energy ray with respect to the said adhesive layer, it is 7.0-15.0N, and an active energy ray is irradiated to the said adhesive layer. The ratio of the indentation stress after irradiating the adhesive layer to the previous indentation stress with the active energy ray is 1.30 to 2.50. Providing a line-curable pressure-sensitive adhesive (Invention 1).

  In the active energy ray-curable pressure-sensitive adhesive according to the invention (invention 1), the indentation stress before irradiation with active energy rays, the indentation stress after irradiation with active energy rays and the ratio thereof are defined as described above. The step following property is excellent before the energy ray irradiation, and after the active energy ray irradiation, the step following property is maintained even under high-temperature and high-humidity conditions, and bubbles are not generated, and the durability is excellent.

  In the said invention (invention 1), the storage elastic modulus in 23 degreeC of the said active energy ray-curable adhesive is 0.01-0 before irradiating an active energy ray with respect to the said active energy ray-curable adhesive. .2 MPa, and preferably 0.02 to 0.5 MPa after the active energy ray-curable adhesive is irradiated with active energy rays (Invention 2).

  In the said invention (invention 2), with respect to the storage elastic modulus in 23 degreeC before irradiating the said adhesive layer with an active energy ray, the storage elastic modulus in 23 degreeC after irradiating the said adhesive layer with an active energy ray The ratio is preferably 1.1 to 2.5 (Invention 3).

  In the said invention (invention 1-3), the storage elastic modulus in 85 degreeC of the said active energy ray-curable adhesive is 0.01 before irradiating an active energy ray with respect to the said active energy ray-curable adhesive. It is preferable to be 0.02 to 0.2 MPa after the active energy ray-curable adhesive is irradiated with active energy rays (Invention 4).

  In the said invention (invention 4), with respect to the storage elastic modulus in 85 degreeC before irradiating the said adhesive layer with an active energy ray, the storage elastic modulus in 85 degreeC after irradiating the said adhesive layer with an active energy ray The ratio is preferably 1.1 to 3.5 (Invention 5).

  Secondly, the present invention is an adhesive sheet comprising two release sheets and an adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets. The pressure-sensitive adhesive sheet is characterized in that the layer is made of the active energy ray-curable pressure-sensitive adhesive (Invention 1 to 5) (Invention 6).

  Thirdly, the present invention is a laminate comprising two hard plates and an adhesive layer that bonds the two hard plates together, wherein the adhesive layer is curable with the active energy ray. A pressure-sensitive adhesive (Invention 1 to 5) is provided by being cured by irradiation with active energy rays (Invention 7).

  In the said invention (invention 7), it is preferable that at least 1 of the said hard board has a level | step difference in the surface at the side of the said adhesive layer (invention 8).

  In the said invention (invention 8), it is preferable that the said level | step difference is a level | step difference by a printing layer (invention 9).

  In the said invention (invention 7-9), at least 1 of the said hard board may also contain 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 is a surface on the pressure-sensitive adhesive layer side. It may be a protective plate having a frame-shaped step (Invention 11).

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

  The active energy ray-curable pressure-sensitive adhesive according to the present invention and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the present invention are excellent in step following ability before irradiation with active energy rays and excellent in durability after irradiation with active energy rays. In a laminate obtained by using such an active energy ray-curable adhesive, even if there is a step on the adhesive layer side, the adhesive layer follows the step, so that there are floats and bubbles near the step. It will not be. In addition, the pressure-sensitive adhesive layer of the laminate is excellent in durability because the step following property is maintained even when it is placed under a high-temperature and high-humidity condition, bubbles are not generated, and the like.

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

Hereinafter, embodiments of the present invention will be described.
[Active energy ray-curable adhesive]
1. Physical Properties The active energy ray-curable pressure-sensitive adhesive according to the present embodiment has the following physical properties. That is, when the active energy ray-curable pressure-sensitive adhesive according to this embodiment is a pressure-sensitive adhesive layer having a thickness of 600 μm, the surface of the pressure-sensitive adhesive layer has a depth of 500 μm at a speed of 6 mm / min in an area of 5 mm × 5 mm. The indentation stress after 10 seconds of pushing is 4.0 to 7.0 N before the active energy ray is irradiated to the pressure-sensitive adhesive layer, and 7 times after the active energy ray is irradiated to the pressure-sensitive adhesive layer. 0.0-15.0N.

  In this specification, the indentation stress is measured by measuring the size of the pressure-sensitive adhesive layer as 50 mm long × 50 mm wide × 600 μm thick, and using a silicon chip having a length of 5 mm × 5 mm wide × 500 μm thick at a temperature of 23 ° C. , Under a relative humidity of 50% RH, using a universal tensile and compression tester (in the test example, “Instron 5581 type” manufactured by Instron) is used.

  When the indentation stress before irradiation with active energy rays is 4.0 to 7.0 N, the active energy ray-curable pressure-sensitive adhesive is excellent in step followability at the time of application before irradiation with active energy rays. Therefore, even if the adherend has a step, the active energy ray-curable adhesive follows the step, so that there is no floating or bubbles in the vicinity of the step. If the indentation stress before irradiation with the active energy beam is less than 4.0 N, the workability such as cutting is deteriorated, or the durability after irradiation with the active energy beam is insufficient, and the indentation stress before irradiation with the active energy beam is 7 If it exceeds 0.0 N, the step following ability at the time of sticking is lowered. The indentation stress before irradiation with this active energy ray is preferably 4.4 to 6.7 N, and particularly preferably 4.6 to 6.5 N.

  On the other hand, since the indentation stress after irradiation with active energy rays is 7.0 to 15.0 N, the active energy ray-curable pressure-sensitive adhesive is subjected to high-temperature and high-humidity conditions (for example, 85 ° C. and 85% after irradiation with active energy rays). Even when left under RH (240 hours), the step following ability is maintained, bubbles are not generated, and the durability is excellent. If the indentation stress after irradiation with the active energy ray is less than 7.0 N, the durability is lowered, and if the indentation stress after irradiation with the active energy ray exceeds 15.0 N, the step following ability is high under high temperature and high humidity conditions. It will not be maintained. The indentation stress after irradiation with this active energy ray is preferably 7.2 to 11.0 N, and particularly preferably 7.4 to 9.5 N.

  The ratio of the indentation stress after irradiation of the active energy beam to the indentation stress before irradiation of the active energy beam (indentation stress after irradiation of the active energy beam / indentation stress before irradiation of the active energy beam) is 1.30-2. 50, preferably 1.35 to 2.20, particularly preferably 1.37 to 1.90. When the ratio of the indentation stress is within the above range, the balance between the step following ability before irradiation with active energy rays and the durability after irradiation with active energy rays can be made suitable.

  The active energy ray-curable pressure-sensitive adhesive according to this embodiment preferably further has the following physical properties. That is, the storage elastic modulus at 23 ° C. of the active energy ray-curable pressure-sensitive adhesive before irradiation with active energy rays is preferably 0.01 to 0.2 MPa, and particularly preferably 0.04 to 0.15 MPa. Further, it is preferably 0.07 to 0.1 MPa. Further, the storage elastic modulus at 85 ° C. of the active energy ray-curable pressure-sensitive adhesive before irradiation with active energy rays is preferably 0.01 to 0.1 MPa, particularly preferably 0.01 to 0.06 MPa. Furthermore, it is preferably 0.02 to 0.04 MPa. In addition, the storage elastic modulus in this specification shall be a value measured by the torsional 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, thereby being excellent in step following ability.

  On the other hand, the storage elastic modulus at 23 ° C. of the active energy ray-curable adhesive after irradiation with active energy rays is preferably 0.02 to 0.5 MPa, and particularly preferably 0.05 to 0.3 MPa. Furthermore, it is preferably 0.09 to 0.2 MPa. Further, the storage elastic modulus at 85 ° C. of the active energy ray-curable adhesive after irradiation with active energy rays is preferably 0.02 to 0.2 MPa, particularly preferably 0.02 to 0.1 MPa. Further, it is preferably 0.03 to 0.05 MPa. The active energy ray-curable pressure-sensitive adhesive after irradiation with active energy rays has superior storage durability by having the above storage elastic modulus.

  Further, the ratio of storage elastic modulus at 23 ° C. after irradiation with active energy rays to storage elastic modulus at 23 ° C. before irradiation with active energy rays (storage elastic modulus after irradiation with active energy rays / storage elastic modulus before irradiation with active energy rays). ) Is preferably 1.1 to 2.5, particularly preferably 1.2 to 2.0, and more preferably 1.3 to 1.7.

  As described above, the active energy ray-curable adhesive cured at 23 ° C. of the active energy ray-curable adhesive after irradiation with the active energy ray (after curing) is excellent in durability. It will be.

  The ratio of the storage elastic modulus at 85 ° C. after irradiation with active energy rays to the storage elastic modulus at 85 ° C. before irradiation with active energy rays (storage elastic modulus after irradiation with active energy rays / storage elastic modulus before irradiation with active energy rays). ) Is preferably 1.1 to 3.5, particularly preferably 1.3 to 2.5, and more preferably 1.4 to 2.0.

  As described above, the active energy ray-curable pressure-sensitive adhesive cured at 85 ° C. after irradiation with the active energy ray (after curing) increases the storage elastic modulus at 85 ° C. Will also have excellent durability.

  When the ratio of the storage elastic modulus at 23 ° C. or 85 ° C. is less than 1.1, the durability improvement effect as described above may not be obtained. On the other hand, when the ratio of the storage elastic modulus at 23 ° C. exceeds 2.5, or the ratio of the storage elastic modulus at 85 ° C. exceeds 3.5, the adhesive strength of the cured active energy ray-curable adhesive decreases. Thus, sufficient durability may not be obtained. When the ratio of storage elastic modulus at 23 ° C. exceeds 2.5, or the ratio of storage elastic modulus at 85 ° C. exceeds 3.5, the three-dimensional network structure formed along with active energy ray curing is It is presumed that it becomes too dense and exacerbates the loss of moisture in the pressure-sensitive adhesive, and may reduce the resistance to moist heat whitening.

2. Material The active energy ray-curable pressure-sensitive adhesive according to the present embodiment (hereinafter sometimes simply referred to as “pressure-sensitive adhesive”) satisfies the above-described physical properties and has the desired pressure-sensitive adhesiveness. Although it may consist of any material, the weight average molecular weight is 200,000 to 900,000, and (meth) acrylic acid ester co-polymer containing 5 to 20% by mass of (meth) acrylic acid as a monomer unit constituting the polymer A pressure-sensitive adhesive composition (hereinafter sometimes referred to as “pressure-sensitive adhesive composition P”) containing the coalescence (A), the active energy ray-curable component (B), and the crosslinking agent (C) is thermally crosslinked. It is preferable that The active energy ray-curable pressure-sensitive adhesive obtained by thermally crosslinking the pressure-sensitive adhesive composition P is easy to satisfy the above-described physical properties and exhibits suitable pressure-sensitive adhesiveness and adhesion to a hard plate or the like. In the present specification, (meth) acrylic acid means both acrylic acid and methacrylic acid. The same applies to other similar terms.

  Specifically, the active energy ray-curable pressure-sensitive adhesive obtained by thermally crosslinking the pressure-sensitive adhesive composition P is in a state where the (meth) acrylic acid ester copolymer (A) is cross-linked by the cross-linking agent (C). ing. On the other hand, the active energy ray-curable component (B) has not yet been cured, and is present in the active energy ray-curable adhesive as it is blended in the adhesive composition P. This active energy ray-curable component (B) is polymerized and cured when active energy rays are applied to the active energy ray-curable adhesive during use (when the adherend is bonded).

(1) (Meth) acrylic acid ester copolymer (A)
The (meth) acrylic acid ester copolymer (A) preferably contains 5 to 20% by mass of (meth) acrylic acid as a monomer unit constituting the polymer, particularly 7 to 15% by mass. More preferably, it is 8 to 12% by mass. When the content of (meth) acrylic acid is in the above range, the crosslinked structure formed by the (meth) acrylic acid ester copolymer (A) and the crosslinking agent (C) becomes good, and the pressure-sensitive adhesive is It has suitable durability. Moreover, since the content of (meth) acrylic acid is in the above range, the apparent cohesive force of the pressure-sensitive adhesive is increased, and the weight average molecular weight and crosslinking density of the (meth) acrylic acid ester copolymer (A) are increased. Since it is presumed that the stress relaxation property can be enhanced while keeping it low, the step following property of the pressure-sensitive adhesive becomes excellent. Furthermore, the pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition P containing the (meth) acrylic acid ester copolymer (A) in which the content of (meth) acrylic acid is in the above range is the curing of the pressure-sensitive adhesive. Later, after applying high-temperature and high-humidity conditions (for example, under the conditions of 85 ° C. and 85% RH for 240 hours), whitening when the temperature is returned to normal temperature and normal humidity is suppressed, that is, excellent in heat-and-heat whitening resistance. It will be. When the (meth) acrylic acid ester copolymer (A) contains (meth) acrylic acid in the above amount as a monomer unit, a predetermined amount of carboxyl groups remains in the resulting adhesive (after thermal crosslinking). It will be. The carboxyl group is a hydrophilic group, and when such a hydrophilic group is present in the adhesive in a predetermined amount, even when the adhesive is placed under high temperature and high humidity conditions after irradiation with active energy rays, the high temperature and high humidity It is presumed that the moisture that has entered the pressure-sensitive adhesive under the conditions is easily removed from the pressure-sensitive adhesive when it returns to normal temperature and humidity, and as a result, whitening of the pressure-sensitive adhesive is suppressed.

  When the content of (meth) acrylic acid as a monomer unit in the (meth) acrylic acid ester copolymer (A) is less than 5% by mass, the active energy ray-curable pressure-sensitive adhesive is particularly inferior in moisture and heat whitening resistance. It may become. On the other hand, when content of (meth) acrylic acid exceeds 20 mass%, the applicability | paintability 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. It is preferable to contain as a component. Thereby, the obtained adhesive can express preferable adhesiveness.

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

  The (meth) acrylic acid ester copolymer (A) contains 40 to 95% by mass of a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms as the monomer unit constituting the polymer. In particular, it is preferably contained in an amount of 80 to 93% by mass, more preferably 88 to 92% by mass.

  The (meth) acrylic acid ester copolymer (A) may contain other monomers as monomer units constituting the polymer, if desired. The other monomer is preferably a monomer that does not contain a reactive functional group in order not to interfere with the action of (meth) acrylic acid. Such other monomers include, for example, (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, and aliphatic rings such as cyclohexyl (meth) acrylate (meta Non-crosslinkable acrylamide such as acrylic ester, acrylamide, methacrylamide, etc. Non-crosslinkable tertiary such as N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate Examples thereof include (meth) acrylic acid ester having an amino group, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

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

  The (meth) acrylic acid ester copolymer (A) preferably has a weight average molecular weight of 200,000 to 900,000, particularly preferably 250,000 to 700,000, and more preferably 300,000 to 500,000. Is preferred. In addition, the weight average molecular weight in this specification is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

  As the weight average molecular weight of the (meth) acrylic acid ester copolymer (A) which is the main component of the adhesive composition P is relatively small as described above, the adhesive composition P is obtained by thermal crosslinking. The pressure-sensitive adhesive has excellent step following ability. When the weight average molecular weight of the (meth) acrylic acid ester copolymer (A) exceeds 900,000, the step following ability 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 after irradiation with active energy rays may be inferior in durability.

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

(2) Active energy ray-curable component (B)
When the pressure-sensitive 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 is excellent in step followability and durability. Become.

  The active energy ray-curable component (B) is not particularly limited as long as it is a component that is cured by irradiation with active energy rays without impeding the effects of the present invention, and may be any of a monomer, an oligomer, or a polymer. Or a mixture thereof. Among them, a polyfunctional acrylate monomer having a molecular weight of less than 1000 that is excellent in compatibility with the (meth) acrylic acid ester copolymer (A) and the like can be preferably exemplified.

  Examples of polyfunctional acrylate monomers having a molecular weight of less than 1000 include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and polyethylene glycol diene. (Meth) acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalate neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified Bifunctional type such as di (meth) acrylate phosphate, di (acryloxyethyl) isocyanurate, allylated cyclohexyl di (meth) acrylate, etc .; trimethylolpropane tri (meth) acrylate , Dipentaerythritol tri (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris (acryloxyethyl) Trifunctional types such as isocyanurate and ε-caprolactone modified tris- (2- (meth) acryloxyethyl) isocyanurate; tetrafunctional types such as diglycerin tetra (meth) acrylate and pentaerythritol tetra (meth) acrylate; propionic acid 5-functional type such as modified dipentaerythritol penta (meth) acrylate; dipentaerythritol hexa (meth) acrylate, caprolactone modified dipentaerythritol hexa (meth) acrylate 6 functional types such as These may be used individually by 1 type and may be used in combination of 2 or more type.

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

  Here, the polyester acrylate oligomer is obtained by, for example, esterifying the hydroxyl group of a polyester oligomer having hydroxyl groups at both ends obtained by condensation of a polyvalent carboxylic acid and a polyhydric alcohol with (meth) acrylic acid. It can be obtained by esterifying the 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 an oxirane ring of a relatively low molecular weight bisphenol type epoxy resin or novolac type epoxy resin with (meth) acrylic acid for esterification. In addition, a carboxyl-modified epoxy acrylate oligomer obtained by partially modifying this epoxy acrylate oligomer with a dibasic carboxylic acid anhydride can also be used. The urethane acrylate oligomer can be obtained, for example, by esterifying a polyurethane oligomer obtained by a reaction between a polyether polyol or a polyester polyol and a polyisocyanate with (meth) acrylic acid. The polyol acrylate oligomer can be obtained by esterifying the hydroxyl group of the polyether polyol with (meth) acrylic acid.

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

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

  The (meth) acrylic acid ester preferably contains a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms, such as methyl (meth) acrylate, ethyl (meth) acrylate, Propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate , Decyl (meth) acrylate, dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. 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 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, ( (Meth) acrylic acid hydroxyalkyl esters such as (meth) acrylic acid 3-hydroxybutyl and (meth) acrylic acid 4-hydroxybutyl; acrylamides such as N-methylol methacrylamide; (meth) acrylic acid monomethylaminoethyl, (meta ) Monoethylaminoethyl (meth) acrylate such as monoethylaminoethyl acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate; acrylic acid, methacrylic acid, crotonic acid, maleic acid, Itaconic acid, citracone Such as ethylenically unsaturated carboxylic acids and the like. These monomers may be used independently and may be used in combination of 2 or more type.

  Examples of the compound having a group that reacts with a (meth) acryloyl group and a crosslinkable functional group include 2-methacryloyloxyethyl isocyanate, 2- (0- [1′-methylpropylideneamino] carboxyamino) ethyl methacrylate, 2-[(3,5-dimethylpyrazolyl) carbonylamino] ethyl methacrylate, 1,1- (bisacryloyloxymethyl) ethyl isocyanate, 2-acryloyloxyethyl isocyanate, 2-acryloyloxyethyl succinate, 2-acryloyloxyethyl Preferred examples include hexahydrophthalimide, ω-carboxy-polycaprolactone monoacrylate, phthalic acid monohydroxyethyl acrylate, 2-hydroxy-3-phenoxypropyl 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 polymer is preferably about 50,000 to 900,000, and particularly preferably about 100,000 to 500,000.

  The active energy ray-curable component (B) can be used by selecting one from among the above-mentioned polyfunctional acrylate monomers, acrylate oligomers and adduct acrylate polymers, or a combination of two or more. It can also be used in combination with 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 with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A). In particular, the amount is preferably 2 to 8 parts by mass, and more preferably 3 to 7 parts by mass. When the content of the active energy ray-curable component (B) is less than 1 part by mass, the durability of the pressure-sensitive adhesive after irradiation with active energy rays may be reduced. When the content of the active energy ray-curable component (B) exceeds 10 parts by mass, the wet heat whitening resistance of the pressure-sensitive adhesive after irradiation with active energy rays may be deteriorated.

(3) Crosslinking agent (C)
The pressure-sensitive adhesive composition P contains the cross-linking agent (C), thereby cross-linking the (meth) acrylic acid ester copolymer (A) to form a three-dimensional network structure. Improve. Moreover, durability can also be provided to the said adhesive after active energy ray irradiation.

  As a crosslinking agent (C), what is necessary is just to react with the reactive group (carboxyl group of (meth) acrylic acid which is a monomer unit) which (meth) acrylic acid ester copolymer (A) has, for example, Isocyanate crosslinking agent, epoxy crosslinking agent, amine crosslinking agent, melamine crosslinking agent, aziridine crosslinking agent, hydrazine crosslinking agent, aldehyde crosslinking agent, oxazoline crosslinking agent, metal alkoxide crosslinking agent, metal chelate crosslinking agent Agents, metal salt crosslinking agents, ammonium salt crosslinking agents, and the like. A crosslinking agent (C) can be used individually by 1 type or in combination of 2 or more types.

  Among the above, it is preferable to use as the crosslinking agent (C) at least one selected from an epoxy-based crosslinking agent and an isocyanate-based crosslinking agent excellent in reactivity with a carboxyl group, and it is particularly preferable to use an epoxy-based crosslinking agent. preferable. A pressure-sensitive adhesive using an epoxy-based cross-linking agent is suitable for optical applications because it is excellent in heat resistance and hardly yellows.

  Examples of the epoxy crosslinking agent include 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl. Examples include ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like.

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

  The content of the crosslinking agent (C) in the adhesive composition P is preferably 0.001 to 2 parts by mass with respect to 100 parts by mass of the (meth) acrylic acid ester copolymer (A), and in particular. The amount is preferably 0.01 to 1 part by mass, and more preferably 0.02 to 0.3 part by mass. When the content of the cross-linking agent (C) is 0.001 part by mass or more, the durability improving effect can be imparted to the pressure-sensitive adhesive after irradiation with active energy rays. When content of a crosslinking agent (C) exceeds 2 mass parts, there exists a possibility that the degree of bridge | crosslinking may become excessive and the level | step difference followability of the adhesive which may be obtained may fall. In addition, the carboxyl group of the (meth) acrylic acid ester copolymer (A) reacts with a large amount of the crosslinking agent (C), and the amount of the carboxyl group remaining in the pressure-sensitive adhesive is reduced. May decrease.

(4) Photopolymerization initiator (D)
In the case where ultraviolet rays are used as the active energy ray irradiated to the active energy ray-curable adhesive, the adhesive composition P preferably further contains a photopolymerization initiator (D). By containing the photopolymerization initiator (D) in this way, the active energy ray-curable component (B) can be efficiently cured, and the polymerization curing time and the amount of active energy ray irradiation can be reduced. it can.

  Examples of such photopolymerization initiator (D) include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, and 2,2-dimethoxy. 2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 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 -Diethylaminobenzophenone, dichlorobenzophenone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethylthioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone 2,4-diethylthioxanthone, benzyldimethyl ketal, acetophenone dimethyl ketal, p-dimethylaminobenzoate, oligo [2-hydroxy-2-methyl-1 [4- (1-methylvinyl) phenyl] propanone], 2 4,6-trimethylbenzoyl-diphenyl-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 in the range of 2 to 15 parts by mass, particularly 4 to 12 parts by mass with respect to 100 parts by mass of the active energy ray-curable component (B).

(5) Various additives For the adhesive composition P, various additives usually used for acrylic pressure-sensitive adhesives, for example, silane coupling agents, antistatic agents, tackifiers, antioxidants, ultraviolet rays, if desired. Absorbers, light stabilizers, softeners, fillers, refractive index adjusters and the like can be added.

  The silane coupling agent is preferably an organosilicon compound having at least one alkoxysilyl group in the molecule and having good compatibility with the (meth) acrylic acid ester copolymer (A). Moreover, when an adhesive is an optical use, the silane coupling agent which has a light transmittance is suitable.

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

  It is preferable that the addition amount of a silane coupling agent is 0.01-1.0 mass part with respect to 100 mass parts of (meth) acrylic acid ester copolymer (A), especially 0.05-0.5. It is preferable that it is a mass part.

(6) Manufacture of adhesive composition Adhesive composition P manufactured (meth) acrylic acid ester copolymer (A), obtained (meth) acrylic acid ester copolymer (A), and activity While mixing an energy-beam curable component (B) and a crosslinking agent (C), if desired, it can manufacture by adding a photoinitiator (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 an ordinary radical polymerization method. The polymerization of the (meth) acrylic acid ester copolymer (A) can be carried out by a solution polymerization method or the like using a polymerization initiator as desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like. Two or more kinds may be used in combination.

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

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

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

  Once the (meth) acrylic acid ester copolymer (A) is obtained, the solution of the (meth) acrylic acid ester copolymer (A) is added to the active energy ray-curable component (B), the crosslinking agent (C), and The adhesive composition P is obtained by adding a polymerization initiator (D) and an additive as desired and mixing them sufficiently.

(7) Production of active energy ray-curable pressure-sensitive adhesive The active energy ray-curable pressure-sensitive adhesive according to the present embodiment is obtained by thermally cross-linking after applying the above pressure-sensitive adhesive composition P. Thermal crosslinking of the adhesive composition P can be performed by heat treatment. This heat treatment can also serve as a drying treatment after the application of the adhesive composition P.

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

  By the heat treatment (and curing), the (meth) acrylic acid ester copolymer (A) is well crosslinked through the crosslinking agent (C), and an active energy ray-curable pressure-sensitive adhesive is obtained. In addition, in this active energy ray-curable pressure-sensitive adhesive, the active energy ray-curable component (B) is present as it is blended in the pressure-sensitive adhesive composition P.

  The active energy ray-curable pressure-sensitive adhesive according to the present embodiment described above is excellent in step following ability before irradiation with active energy rays and excellent in durability after irradiation with active energy rays. In particular, the active energy ray-curable pressure-sensitive adhesive obtained by thermally crosslinking the adhesive composition P is also excellent in moisture and heat whitening resistance after irradiation with active energy rays.

[Adhesive sheet]
As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 according to this embodiment includes two release sheets 12a and 12b and the two release sheets 12a so as to be in contact with the release surfaces of the two release sheets 12a and 12b. , 12b and an adhesive layer 11 sandwiched between the two layers. In addition, the release surface of the release sheet in this specification refers to a surface having peelability in the release sheet, and includes both a surface that has been subjected to a release treatment and a surface that exhibits peelability without being subjected to a release treatment. .

1. The pressure-sensitive adhesive layer The pressure-sensitive adhesive layer 11 in the pressure-sensitive adhesive sheet 1 is composed of the above-described active energy ray-curable pressure-sensitive adhesive, exhibits adhesiveness before irradiation with active energy rays, and is cured when irradiated with active energy rays. Shows adhesion. The pressure-sensitive adhesive layer 11 is preferably composed of a heat-crosslinked 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 (value measured according to JIS K7130) is preferably 50 to 400 μm, particularly preferably 70 to 300 μm, and more preferably 90 to 250 μm. The pressure-sensitive adhesive layer 11 may be formed as a single layer or may be formed by laminating a plurality of layers.

  If the thickness of the pressure-sensitive adhesive layer 11 is less than 50 μm, sufficient step followability may not be obtained, and if the thickness of the pressure-sensitive adhesive layer 11 exceeds 400 μm, workability may be reduced.

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

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

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

3. Manufacture of an adhesive sheet As an example, the manufacturing method of the adhesive sheet 1 which uses the adhesive composition P is demonstrated.
As one production example of the pressure-sensitive adhesive sheet 1, the pressure-sensitive adhesive composition P is applied to the release surface of one release sheet 12 a (or 12 b) and subjected to heat treatment to thermally cross-link the pressure-sensitive adhesive composition P. Then, after forming the coating layer, the release surface of the other release sheet 12b (or 12a) is overlaid on the coating layer. When a curing period is required, a curing period is set, and when the curing period is unnecessary, the coating layer becomes the pressure-sensitive adhesive layer 11 as it is. Thereby, the said adhesive sheet 1 is obtained.

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

  For example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used as a method for applying the coating solution of the adhesive composition P. The heat treatment conditions for the applied adhesive composition P are as described above.

  In the above pressure-sensitive adhesive sheet 1, the pressure-sensitive adhesive layer 11 before irradiation with active energy rays is excellent in step followability. Therefore, even when the adherend has a level difference, a gap or a bubble is present between the level difference and the pressure-sensitive adhesive layer 11. The pressure-sensitive adhesive layer 11 can fill the step. Moreover, the adhesive layer 11 becomes excellent in durability by being cured by irradiation with active energy rays. In particular, the pressure-sensitive adhesive layer 11 obtained by thermally crosslinking the pressure-sensitive adhesive composition P is also excellent in moisture and heat whitening resistance after irradiation with active energy rays.

  As will be described later, 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 to each other.

[Laminate]
As shown in FIG. 2, the laminate 2 according to the present embodiment is positioned between the first hard plate 21, the second hard plate 22, and the first hard plate 21 and the second hard plate 21. It is comprised from the adhesive layer 11 which bonds the hard board 22 mutually. Moreover, in the laminated body 2 which concerns on this embodiment, the 1st hard board 21 has a level | step difference in the surface at the side of the adhesive layer 11, and specifically has a level | step difference by the printing layer 3. FIG. .

  The 1st hard board 21 and the 2nd hard board 22 will not be specifically limited if the adhesive layer 11 can adhere | attach. Moreover, the same material may be sufficient as the 1st hard board 21 and the 2nd hard board 22, and a different material may be sufficient as it.

  As the first hard plate 21 and the second hard plate 22, for example, a glass plate, a plastic plate, a metal plate, a semiconductor plate, etc., or a laminate thereof, or a plate shape such as a display module, a solar cell module, etc. Hard products and the like.

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

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

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

  Examples of the optical member include a polarizing plate (polarizing film), a polarizer, a retardation plate (retarding film), a viewing angle compensation film, a brightness enhancement film, a contrast enhancement film, a liquid crystal polymer film, a diffusion film, and a hard coat film. And a semi-transmissive reflective film.

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

  In the laminate 2 according to the present embodiment, it is preferable that at least one of the first hard plate 21 and the second hard plate 22 contains a polarizing plate. Moreover, the 2nd hard board 22 in the laminated body 2 which concerns on this embodiment is a display body module or its part (for example, optical members, such as a polarizing plate), and the 1st hard board 21 is a glass plate etc. A protective plate made of In this case, the printing layer 3 is generally formed in a frame shape on the pressure-sensitive adhesive layer 11 side of the first hard plate 21.

  The material which comprises the printing layer 3 is not specifically limited, The well-known material for printing is used. The thickness of the printing layer 3, that is, the height of the step, is preferably 3 to 45 μm, particularly preferably 5 to 35 μm, more preferably 7 to 25 μm, and 7 to 15 μm. Is most preferred.

  Further, the thickness of the printing layer 3 (the height of the step) is preferably 3 to 30% of the thickness of the pressure-sensitive adhesive layer 11, particularly preferably 3.2 to 20%, and more preferably 3 It is preferable that it is 5 to 15%. As a result, the pressure-sensitive adhesive layer 11 reliably follows the step formed by the printing layer 3, and no floating or bubbles are generated in the vicinity of the step.

  The pressure-sensitive adhesive layer 11 of the laminate 2 according to this embodiment is a pressure-sensitive adhesive layer composed of the above-described active energy ray-curable pressure-sensitive adhesive, preferably the pressure-sensitive adhesive layer 11 in the pressure-sensitive adhesive sheet 1 described above by irradiation with active energy rays. It has been cured. Here, active energy rays refer to those having energy quanta among electromagnetic waves or charged particle beams, and specific examples include ultraviolet rays and electron beams. Among active energy rays, ultraviolet rays that are easy to handle are particularly preferable.

Irradiation with ultraviolet rays can be performed by a high-pressure mercury lamp, a fusion H lamp, a xenon lamp, or the like, and the irradiation amount of ultraviolet rays is preferably about 50 to 1000 mW / cm ^{2 in} illuminance. Further, the light quantity is preferably 50~10000mJ / cm ^2, more preferably 80~5000mJ / cm ^2, and particularly preferably 200~2000mJ / cm ^2. On the other hand, the electron beam irradiation can be performed by an electron beam accelerator or the like, and the electron beam irradiation amount 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 cured by irradiation with active energy rays is excellent in durability and also excellent in moisture and heat whitening resistance.

  In order to manufacture the laminate 2, as an example, first, one release sheet 12 a (or 12 b) of the pressure-sensitive adhesive sheet 1 is peeled, and the pressure-sensitive adhesive layer 11 exposed from the pressure-sensitive adhesive sheet 1 and the first hard plate 21. (Or the second hard plate 22). Next, the other release sheet 12b (or 12a) is peeled from the adhesive layer 11 of the adhesive sheet 1, and the exposed adhesive layer 11 and the second hard plate 22 (or the first hard plate 21) of the adhesive sheet 1 are exposed. ).

  When the pressure-sensitive adhesive layer 11 and the first hard plate 21 are bonded in the above process, the pressure-sensitive adhesive layer 11 is excellent in step following ability, so that a gap is formed between the step formed by the printing layer 3 and the pressure-sensitive adhesive layer 11. It is difficult, and the pressure-sensitive adhesive layer 11 can fill the step.

  After that, the adhesive layer 11 is cured by irradiating the adhesive layer 11 with active energy rays from either the first hard plate 21 or the second hard plate 22. At this time, the hard plate on the side irradiated with the active energy ray needs to be active energy ray transmissive.

  In the laminate 2 described above, since the pressure-sensitive adhesive layer 11 before irradiation with active energy rays is excellent in level difference followability, it is difficult to form voids or bubbles between the level difference due to the printing layer 3 and the pressure-sensitive adhesive layer 11. In addition, the pressure-sensitive adhesive layer 11 cured by irradiation with active energy rays maintains step following ability even when subjected to high-temperature and high-humidity conditions (for example, 85 ° C. and 85% RH for 240 hours). Etc. are prevented, 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 an active energy ray, and after being subjected to a high-temperature and high-humidity condition, whitening when returning to room temperature is suppressed. Excellent moisture and heat whitening resistance.

  The excellent moisture and heat whitening resistance of the pressure-sensitive adhesive layer 11 cured by irradiation with active energy rays can be evaluated as follows. For example, the both sides of the adhesive layer 11 are sandwiched between two non-alkali glasses having a thickness of 1.1 mm, and the active energy rays having the above illuminance and light amount are irradiated from at least one side through the non-alkali glass. To obtain a laminate. The laminate is stored for 240 hours under conditions of 85 ° C. and 85% RH (wet heat condition), and then taken out under normal temperature and humidity of 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 can be quantitatively evaluated based on the haze value. Specifically, a value obtained by subtracting the haze value (%) before the wet heat condition from the haze value (%) after the wet heat condition in the laminate (a value measured according to JIS K7136: 2000; the same applies hereinafter). The haze value can be evaluated later. The increase in haze value after wet heat conditions is preferably less than 5.0 points, particularly preferably less than 1.0 points. In the above evaluation, it is preferable to use a non-alkali glass having a haze value of approximately 0%. Further, the haze value of the pressure-sensitive adhesive layer after the wet heat condition is preferably 1.0% or less, particularly preferably 0.9% or less, and further preferably 0.8% or less. .

  The pressure-sensitive adhesive layer 11 preferably has a total light transmittance (value measured in accordance with JIS K7361-1: 1997) of 80% or more, particularly preferably 90% or more. It is preferably 99% or more. When the total light transmittance is 80% or more, the transparency is high and the optical application is suitable. Such total light transmittance can be easily achieved by using an epoxy-based crosslinking agent that does not easily yellow the pressure-sensitive adhesive layer 11 as the crosslinking agent (C). In addition, the total light transmittance of the adhesive layer 11 hardly changes before and after the irradiation with active energy rays.

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

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

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

[Example 1]
1. Preparation of (meth) acrylic acid ester copolymer In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device and nitrogen introduction tube, 90 parts by mass of n-butyl acrylate, 10 parts by mass of acrylic acid, ethyl acetate 200 parts by mass and 0.18 parts by mass of 2,2′-azobisisobutyronitrile were charged, and the air in the reaction vessel was replaced with nitrogen gas. While stirring in this nitrogen atmosphere, the reaction solution was heated to 60 ° C., reacted for 16 hours, and then cooled to room temperature. Here, the molecular weight of a part of the obtained solution was measured by the method described later, and the production of a (meth) acrylic acid ester copolymer (A) having a weight average molecular weight of 400,000 was confirmed.

2. Preparation of pressure-sensitive adhesive composition 100 parts by weight of the (meth) acrylic acid ester copolymer (A) obtained in the above step (1) (in terms of solid content; the same applies hereinafter) and the active energy ray-curable component (B) 5 parts by weight of polyethylene glycol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name “NK Ester A-400”, solid content concentration: 100% by mass) and 1,3- as an epoxy-based crosslinking agent (C) 0.06 part by mass of bis (N, N-diglycidylaminomethyl) cyclohexane (Mitsubishi Gas Chemical Co., Ltd., product name “TETRAD-C”, solid content concentration: 100% by mass) and 3-silane as a silane coupling agent Glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., product name “KBM-403”) 0.2 parts by weight, and light weight diluted with methyl ethyl ketone to a solid content concentration of 50% by weight 1-hydroxycyclohexyl phenyl ketone (manufactured by BASF, product name “Irgacure 184”) 0.25 part by mass as the initiator (D) is mixed, sufficiently stirred, and diluted with methyl ethyl ketone to obtain a solid A coating solution of the adhesive composition having a partial concentration of 39% by mass was obtained.

Here, Table 1 shows the composition of the adhesive composition. Details of the abbreviations and the like described in Table 1 are as follows.
[(Meth) acrylic acid ester copolymer]
BA: n-butyl acrylate AA: acrylic acid
[Crosslinking agent]
Epoxy: 1,3-bis (N, N-diglycidylaminomethyl) cyclohexane (manufactured by Mitsubishi Gas Chemical Company, product name “TETRAD-C”)
Isocyanate: Trimethylolpropane-modified tolylene diisocyanate (manufactured by Nippon Polyurethanes, product name “Coronate L”)

3. Production of pressure-sensitive adhesive sheet Peeling of a heavy-peelable release sheet (product name "SP-PET752150", manufactured by Lintec Corporation), in which one side of a polyethylene terephthalate film was subjected to a release treatment with a silicone-based release agent The treated surface was coated with a knife coater so that the thickness after drying was 100 μm, and then heated at 100 ° C. for 4 minutes to form a coated layer. Similarly, the same adhesive composition coating solution was applied to the release-treated surface of a light release-type release sheet (product name “SP-PET382120” manufactured by Lintec Corporation) in which one side of a polyethylene terephthalate film was release-treated with a silicone-based release agent. After coating with a knife coater so that the thickness after drying was 100 μm, the coating layer was formed by heat treatment at 100 ° C. for 4 minutes.

  Subsequently, the heavy release type release sheet with the coating layer obtained above and the light release type release sheet with the coating layer obtained above were bonded so that both coating layers were in contact with each other. By curing for 7 days under the condition of 50% RH, a pressure-sensitive adhesive sheet having a structure of heavy release type release sheet / pressure-sensitive adhesive layer (thickness: 200 μm) / light release type release sheet was produced. The thickness of the pressure-sensitive adhesive layer is a value measured using a constant pressure thickness measuring instrument (manufactured by Teclock, product name “PG-02”) in accordance with JIS K7130.

[Examples 2-8, Comparative Examples 1-3]
The proportion of each monomer constituting the (meth) acrylic acid ester copolymer (A), the weight average molecular weight of the (meth) acrylic acid ester copolymer (A), the type and formulation of the active energy ray-curable component (B) Except for changing the amount, the type and blending amount of the crosslinking agent (C), the blending amount of the photopolymerization initiator (D), the blending amount of the silane coupling agent, and the thickness of the pressure-sensitive adhesive layer as shown in Table 1, A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1. In Example 2, the thickness of each coating layer in the heavy release type release sheet with the coating layer and the light release type release sheet with the coating layer was 75 μm and the thickness of the pressure sensitive adhesive layer was 150 μm. Produced. In Example 7, as the active energy ray-curable component (B), ε-caprolactone-modified tris- (2-acryloxyethyl) isocyanurate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name “NK ester A-9300-”) In Example 8, pentaerythritol triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., product name “NK ester A-” was used as the active energy ray-curable component (B). TMM-3L ", triester: 55 mass%, solid content concentration: 100 mass%).

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

[Test Example 1] (Measurement of indentation stress)
The light release release sheet and the heavy release release sheet were peeled off from the pressure sensitive adhesive sheet obtained in the example or comparative example, and a plurality of pressure sensitive adhesive layers were laminated to a thickness of 600 μm. The obtained laminate of the pressure-sensitive adhesive layer was cut into a length of 50 mm × width of 50 mm, and this was used as a sample (a sample before ultraviolet irradiation).

  On the other hand, a silicon chip of 5 mm length × 5 mm width × 600 μm thickness obtained by dicing from a silicon wafer was prepared. Under the temperature of 23 ° C. and relative humidity of 50% RH, the silicon chip is placed on the center of the surface of the sample, and a universal tensile / compression tester (Instron, product name “Instron 5581”) is installed. The silicon chip was pushed into the sample at a speed of 6 mm / min to a depth of 500 μm, stopped as it was, and the indentation stress (N) 10 seconds after the indentation was measured.

In addition, the pressure-sensitive adhesive layer is cured by irradiating a sample similar to the above with UV irradiation under the following conditions using an UV irradiation device (product name “Igrantage ECS-401GX” manufactured by Eye Graphics Co., Ltd.). Thus, a sample after ultraviolet irradiation was obtained. About the obtained sample after ultraviolet irradiation, the indentation stress (N) was measured like the sample before ultraviolet irradiation.
[UV irradiation conditions]
・ Light source: High-pressure mercury lamp ・ Light quantity: 1000 mJ / cm ²
Illuminance: 200 mW / cm ²

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

[Test Example 2] (Measurement of storage elastic modulus)
The light release type release sheet and the heavy release type release sheet were peeled off from the pressure sensitive adhesive sheet obtained in Examples or Comparative Examples, and a plurality of pressure sensitive adhesive layers were laminated so as to have a thickness of 0.6 mm. A cylindrical body (height 0.6 mm) having a diameter of 8 mm was punched out from the obtained laminate of the pressure-sensitive adhesive layer, and this was used as a sample (sample before ultraviolet irradiation).

About the said sample, based on JISK7244-6, the storage elastic modulus (MPa) was measured on condition of the following by the torsional shear method using the viscoelasticity measuring apparatus (The product name "MCR300" by Physica).
Measurement frequency: 1Hz
Measurement temperature: 23 ° C, 85 ° C

In addition, the pressure-sensitive adhesive layer is cured by irradiating a sample similar to the above with UV irradiation under the following conditions using an UV irradiation device (product name “Igrantage ECS-401GX” manufactured by Eye Graphics Co., Ltd.). Thus, a sample after ultraviolet irradiation was obtained. About the obtained sample after ultraviolet irradiation, the storage elastic modulus (MPa) was measured like the sample before ultraviolet irradiation.
[UV irradiation conditions]
・ Light source: High-pressure mercury lamp ・ Light quantity: 1000 mJ / cm ²
Illuminance: 200 mW / cm ²

  From the above measurement results, the ratio of the storage elastic modulus after UV irradiation to the storage elastic modulus before UV irradiation at 23 ° C. and 85 ° C. (storage elastic modulus after UV irradiation / storage elastic modulus before UV irradiation) Calculated. The measurement results and calculation results are shown in Table 2.

[Test Example 3] (Moisture and heat whitening evaluation)
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet obtained in the example or comparative example is sandwiched between two sheets of non-alkali glass having a thickness of 1.1 mm, and irradiated with ultraviolet rays under the ultraviolet irradiation conditions of Test Example 1 through one glass. Thus, a laminate was obtained. About the laminated body, haze value (%) was measured according to JISK7136: 2000 using the haze meter (The Nippon Denshoku Industries Co., Ltd. make, product name "NDH2000").

  Next, the laminate was stored for 240 hours under wet heat conditions of 85 ° C. and 85% RH. Thereafter, the temperature was returned to room temperature and normal humidity of 23 ° C. and 50% RH, and the laminate was subjected to a haze value according to JIS K7136: 2000 using a haze meter (product name “NDH2000” manufactured by Nippon Denshoku Industries Co., Ltd.). %). In addition, the said haze value was measured within 30 minutes after returning a laminated body to normal temperature normal humidity.

  Based on the above results, the increase in haze value after wet heat condition was calculated by subtracting the haze value (%) before wet heat condition from the haze value (%) after wet heat condition. Humidity and heat whitening resistance is good (○) when the haze value increase after wet heat condition is less than 1.0 point, and wet heat and heat whitening suitability when haze value increase after wet heat condition is 1.0 point or more and less than 5.0 point A value having a haze value increase of 5.0 points or more within the value (Δ) and after the moist heat condition was evaluated as a poor heat and heat whitening resistance (x). The results are shown in Table 2.

[Test Example 4] (Step following / durability test)
(A) Preparation of sample for evaluation On the surface of a glass plate (manufactured by NSG Precision, product name “Corning Glass Eagle XG”, length 90 mm × width 50 mm × thickness 0.5 mm), an ultraviolet curable ink (made by Teikoku Ink, The product name “POS-911 Black”) was screen-printed in a frame shape (outside: 90 mm long × 50 mm wide, 5 mm wide) so that the coating thickness was 8 μm and 15 μm. Next, irradiation with ultraviolet rays (80 W / cm ² , ^two metal halide lamps, lamp height of 15 cm, belt speed of 10 to 15 m / min) is performed to cure the printed ultraviolet curable ink, and a level difference due to printing (level difference) Stepped glass plates having a thickness of 8 μm and 15 μm) were produced.

  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, the light release type release sheet was removed, and the pressure-sensitive adhesive layer was exposed. And using the laminator (The product name "LPD3214" by the Fuji plastic company), the adhesive sheet was laminated | stacked on the glass plate with a level | step difference so that an adhesive layer might cover the frame-like printing whole surface.

Thereafter, the following samples for evaluation (1) and (2) were prepared.
(1) After the lamination, the heavy release type release sheet was peeled off, and a glass plate (product name “Corning Glass Eagle XG”, product length “Corning Glass Eagle XG”, length 90 mm × width 50 mm × thickness 0.5 mm) Was laminated with the laminator to prepare a sample for evaluation.

(2) Separately prepared a hard plate in which a polarizing plate was laminated on a glass plate (manufactured by NSG Precision, product name “Corning Glass Eagle XG”, 90 mm long × 50 mm wide × 0.5 mm thick) via an adhesive. . Then, the heavy release release sheet of the pressure sensitive adhesive sheet laminated on the stepped glass plate obtained in the above step is peeled off, and the exposed pressure sensitive adhesive layer surface and the polarizing plate surface of the hard plate are in contact with each other. Both samples were laminated with a laminator to prepare a sample for evaluation.

(B) Evaluation of step followability (initial) The obtained samples for evaluation (1) and (2) were pressurized at 0.5 MPa and 50 ° C. for 30 minutes in an autoclave manufactured by Kurihara Seisakusho. Thereafter, it was visually confirmed whether or not there were bubbles in the pressure-sensitive adhesive layer (particularly in the vicinity of the step due to the printing layer). When there was no bubble, the initial step following property was good (◯), and when there was a bubble, the initial step following property was poor (×). The results are shown in Table 2.

(C) Evaluation of durability (step difference followability after durability) Next, the samples for evaluation (1) and (2) were stored for 240 hours under a wet heat condition of 85 ° C. and 85% RH. Thereafter, it was visually confirmed whether or not there were bubbles in the pressure-sensitive adhesive layer (particularly in the vicinity of the step due to the printing layer). Those without bubbles were evaluated as good (◯) for durability (step followability after durability), and those with bubbles were evaluated as poor (×) for durability (step followability after durability). The results are shown in Table 2.

[Test Example 5] (Measurement of total light transmittance)
The pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet obtained in Examples or Comparative Examples was bonded to glass, and this was used as a measurement sample. After performing background measurement with glass, the total light transmittance (%) of the above measurement sample was measured using a haze meter (Nippon Denshoku Industries Co., Ltd., NDH-2000) according to JIS K7361-1: 1997. ) Was measured. The results are shown in Table 2.

  As can be seen from Table 2, the pressure-sensitive adhesive layers obtained in the examples were excellent in step following ability before irradiation with ultraviolet rays, and were excellent in durability and resistance to moist heat whitening after irradiation with ultraviolet rays.

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

DESCRIPTION OF SYMBOLS 1 ... Adhesive sheet 11 ... Adhesive layer 12a, 12b ... Release sheet 2 ... Laminated body 21 ... 1st hard board 22 ... 2nd hard board 3 ... Printing layer

Claims (12)

An active energy ray-curable adhesive that cures upon irradiation with an active energy ray,
When the active energy ray-curable pressure-sensitive adhesive is a pressure-sensitive adhesive layer having a thickness of 600 μm,
The indentation stress 10 seconds after the surface of the pressure-sensitive adhesive layer was pushed to a depth of 500 μm at a speed of 6 mm / min in an area of 5 mm × 5 mm,
Before irradiating the adhesive layer with active energy rays, it is 4.0 to 7.0 N,
After irradiating the adhesive layer with active energy rays, it is 7.0 to 15.0 N,
The ratio of the indentation stress after irradiating the adhesive layer with active energy rays to the indentation stress before irradiating the adhesive layer with active energy rays is 1.30 to 2.50. Active energy ray-curable adhesive. The storage elastic modulus at 23 ° C. of the active energy ray-curable adhesive is
Before irradiating the active energy ray-curable adhesive with active energy rays, it is 0.01 to 0.2 MPa,
The active energy ray-curable pressure-sensitive adhesive according to claim 1, which is 0.02 to 0.5 MPa after the active energy ray-curable pressure-sensitive adhesive is irradiated with active energy rays.   The ratio of the storage elastic modulus at 23 ° C. after irradiating the adhesive layer with active energy rays to the storage elastic modulus at 23 ° C. before irradiating the adhesive layer with active energy rays is 1.1-2. The active energy ray-curable pressure-sensitive adhesive according to claim 2, wherein the pressure-sensitive adhesive is 5. The storage elastic modulus at 85 ° C. of the active energy ray-curable adhesive is
Before irradiating the active energy ray-curable adhesive with active energy rays, it is 0.01 to 0.1 MPa,
The active energy ray curing according to any one of claims 1 to 3, wherein the active energy ray curable pressure-sensitive adhesive is 0.02 to 0.2 MPa after being irradiated with an active energy ray. Adhesive.   The ratio of the storage elastic modulus at 85 ° C. after irradiating the adhesive layer with active energy rays to the storage elastic modulus at 85 ° C. before irradiating the adhesive layer with active energy rays is 1.1 to 3. The active energy ray-curable pressure-sensitive adhesive according to claim 4, wherein the pressure-sensitive adhesive is 5. Two release sheets,
An adhesive sheet comprising an adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets,
The said adhesive layer consists of an active energy ray hardening adhesive as described in any one of Claims 1-5, The adhesive sheet characterized by the above-mentioned. Two hard plates,
A laminate comprising an adhesive layer that bonds the two hard plates together,
The said adhesive layer is what hardened | cured the active energy ray hardening adhesive as described in any one of Claims 1-5 by irradiation of an active energy ray, The laminated body characterized by the above-mentioned.   The laminate according to claim 7, wherein at least one of the hard plates has a step on the surface on the pressure-sensitive adhesive layer side.   The laminate according to claim 8, wherein the step is a step due to a printed layer.   The laminate according to any one of claims 7 to 9, wherein at least one of the hard plates includes a polarizing plate. One of the two hard plates is a display module or a part thereof,
The laminate according to any one of claims 7 to 9, wherein the other of the two hard plates is a protective plate having a frame-shaped step on the surface on the pressure-sensitive adhesive layer side.   The total light transmittance of the said adhesive layer is 80% or more, The laminated body as described in any one of Claims 7-11 characterized by the above-mentioned.

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