WO2015137178A1 - Method for manufacturing layered body used to constitute image display device - Google Patents

Abstract

　Provided is a novel method for manufacturing a layered article used to constitute an image display device, in which a sheet-form configuration can be maintained at room temperature, adhesiveness can be provided to a degree that allows separation, and constituent members of the image display device can be securely bonded together through final crosslinking upon flow properties being retained by hot melting. Proposed is a method for manufacturing a layered body used to configure an image display device, the method being characterized in having the following steps (1) to (3) at a minimum. (1) Preparing an adhesive resin composition containing an acrylic copolymer (A) comprising a graft copolymer provided with a macromonomer as a branch component, a crosslinking agent (B), and a photopolymerization initiator (C); and molding a single-layer or multilayer transparent double-sided adhesive material into the form of a sheet, the material being provided with adhesive layers comprising the adhesive resin composition. (2) Affixing and layering two image-display-device-constituting members interposed by the transparent double-sided adhesive material. (3) Irradiating the adhesive layer of the transparent double-sided adhesive material with active energy rays from the outer side of at least one of the image-display-device-constituting members, and crosslinking the adhesive layer so as to bond the two image display device constituent members.

Description

Manufacturing method of laminate for constituting image display device

The present invention relates to a transparent double-sided pressure-sensitive adhesive material excellent in followability to uneven surfaces and storage stability. In particular, manufacture of a laminate for constituting an image display device that can be suitably used as a constituent member of an image display device such as a personal computer, a mobile terminal (PDA), a game machine, a television (TV), a car navigation system, a touch panel, a pen tablet, etc. Regarding the method.

In recent years, in order to improve the visibility of an image display device, an image display panel such as a liquid crystal display (LCD), a plasma display (PDP) or an electroluminescence display (ELD), and a protection disposed on the front side (viewing side) thereof. A space between the panel and the touch panel member is filled with an adhesive sheet, a liquid adhesive, or the like to suppress reflection of incident light or outgoing light from a display image at the air layer interface.

As a method of filling the gap between the constituent members for an image display device with an adhesive, a method of filling the gap with a liquid adhesive resin composition containing an ultraviolet curable resin and then curing it by irradiating with ultraviolet rays. Is known (Patent Document 1).

Also known is a method of filling a gap between component members for an image display device using an adhesive sheet. For example, Patent Document 2 discloses a pressure-sensitive adhesive sheet that is primarily cross-linked by ultraviolet rays as a method of manufacturing a laminated body for an image display device having a configuration in which an image display device constituent member is laminated on at least one side of a transparent double-sided pressure-sensitive adhesive sheet. Is disclosed in which a pressure-sensitive adhesive sheet is irradiated with ultraviolet rays through the image display device constituting member and then secondarily cured after being bonded to the image display device constituting member.

Patent Document 3 discloses a sheet using a hot melt type adhesive composition having a loss tangent at 25 ° C. of less than 1 based on urethane (meth) acrylate having a weight average molecular weight of 20,000 to 100,000. Is disclosed.

Further, Patent Document 4 discloses a touch panel comprising a (meth) acrylic polymer obtained by copolymerizing a monomer containing a (meth) acrylic monomer having a crosslinkable functional group and a specific macromer, and a crosslinking agent. A pressure-sensitive adhesive layer suitable for pasting is disclosed.

Patent Document 5 discloses a method for manufacturing an image display device constituting laminate having a structure in which image display device constituting members are laminated via a transparent double-sided pressure-sensitive adhesive sheet, and includes at least the following (1) and The manufacturing method of the laminated body for image display apparatus structures characterized by having the process of (2) is disclosed.
(1) A step of forming a transparent double-sided pressure-sensitive adhesive sheet before secondary curing by forming the pressure-sensitive adhesive composition into a single-layer or multi-layered sheet, UV-crosslinking this and performing primary curing.
(2) After the two image display device constituent members are laminated via the transparent double-sided adhesive sheet before secondary curing, ultraviolet rays are irradiated from at least one image display device constituent member side, and the secondary material is passed through this member. A step of subjecting the transparent double-sided PSA sheet before curing to UV-curing by secondary crosslinking.

International Publication No. 2010/027041 Japanese Patent No. 4971529 International Publication No. 2010/038366 JP 2013-18227 A JP 2012-184423 A

When sticking an image display device component using an adhesive sheet, it should have adequate adhesiveness in a normal state, that is, at room temperature, for example, adhesive enough to be peeled off (referred to as “tackiness”). It is easy to perform positioning when sticking and is very convenient for work.

In addition, in the field of image display devices, mainly mobile phones and portable terminals, in addition to thinning and high precision, design diversification is progressing, and new problems have arisen accordingly. For example, a black concealment portion is conventionally printed in a frame shape on the peripheral portion of the surface protection panel. However, with the diversification of the design, the frame concealment portion other than black is printed. Forming in color is starting to take place. When the concealment part is formed with a color other than black, the concealability is low with a color other than black, and therefore the height of the concealment part, that is, the printing part tends to be higher than that of black. For this reason, the pressure-sensitive adhesive sheet for laminating components having such a printing unit is required to have a print level followability that can fill up every corner following a large print level.
Among them, for example, when the surface protection panel on which the printing unit is formed is bonded to another image display device constituent member via the adhesive sheet, it can be filled to every corner following the printing step, If the surface of the pressure-sensitive adhesive sheet is not smooth, the pressure-sensitive adhesive sheet is distorted or deformed. Therefore, the pressure-sensitive adhesive sheet is required to have fluidity.

On the other hand, when the pressure-sensitive adhesive sheet flows in a normal state, that is, at room temperature, the shape as a sheet cannot be maintained, and the storage stability of the pressure-sensitive adhesive sheet and the workability during handling are impaired.
Therefore, the hot melt type sheet in the prior art is generally a sheet having no tackiness using an adhesive composition having a certain degree of rigidity in a room temperature region in order to obtain storage stability. . For this reason, the hot-melt type sheet needs to preheat the adherend from the positioning stage when pasting, and the work is complicated compared to the pressure-sensitive adhesive sheet that can be stuck at room temperature only by pressure bonding Was holding.

Therefore, the present invention can maintain a sheet-like shape in a normal state, that is, a room temperature state, and has a peelable adhesiveness (referred to as “tackiness”). Like the pressure-sensitive adhesive sheet, it can be attached at room temperature. Furthermore, after the image display device constituent members are laminated via the pressure-sensitive adhesive sheet, the image display device constituent members can be bonded by cross-linking. It is intended to provide a method for manufacturing a laminated body for device configuration.

The present invention relates to a method for producing a laminate for constituting an image display device having a constitution in which image display device constituting members are laminated via a transparent double-sided adhesive material, and includes at least the following (1) to (3): The manufacturing method of the laminated body for image display apparatus structures characterized by having a process.
(1) A pressure-sensitive adhesive resin composition comprising an acrylic copolymer (A) comprising a graft copolymer having a macromonomer as a branch component, a crosslinking agent (B), and a photopolymerization initiator (C). And forming a single-layer or multilayer transparent double-sided pressure-sensitive adhesive material having a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive resin composition into a sheet.
(2) The process of sticking and laminating | stacking two image display apparatus structural members through the said transparent double-sided adhesive material.
(3) A step of irradiating the adhesive layer of the transparent double-sided pressure-sensitive adhesive material from the outside of at least one of the image display device constituent members, crosslinking the adhesive layer, and bonding the two image display device constituent members .

The transparent double-sided pressure-sensitive adhesive material obtained in step (1) does not have a chemical cross-linked structure, but has a physical cross-linked structure by aggregating macromonomers constituting the branch components of the base polymer. Thus, the flow in a normal state, that is, at room temperature is suppressed, and the sheet shape can be maintained. Moreover, the transparent double-sided pressure-sensitive adhesive material obtained in the step (1) has an adhesive property (“ (Referred to as “tackiness”). Moreover, when the said adhesive material is heated, the said aggregation of macromonomer will be dissolved, a physical crosslinked structure will be eliminated, and high fluidity | liquidity can be expressed. Furthermore, adherends can be firmly bonded to each other by irradiating light rays, that is, active energy rays. Thus, it is a transparent double-sided pressure-sensitive adhesive material having the advantages of a pressure-sensitive adhesive sheet and a hot melt sheet.
Therefore, using such a transparent double-sided adhesive material obtained in step (1), the following steps (2) to (3) can be realized to produce a laminate for constituting an image display device.
The “chemically crosslinked structure” means a structure that is crosslinked through a chemical bond, and the “physical crosslinked structure” does not involve a chemical bond and aggregates by a physical action. It means the state.

In step (2), two image display device components can be attached via the transparent double-sided adhesive material while maintaining the sheet shape, so positioning is easy when attaching and it is very convenient for work. It is.
In the step (3), the adhesive layer can be cured by irradiating active energy to the uncrosslinked transparent double-sided pressure-sensitive adhesive material via the image display device constituent member. can do. Therefore, for example, the adhesive force and the cohesive force that can sufficiently counter the gas pressure of the outgas generated from the protective panel or the like can be provided.
In addition, when the laminate obtained in the step (2) is heated to a temperature capable of being heated and melted (hot melt), it has fluidity and there is a large printing step on the bonding surface. However, it is possible to fill up every corner by arbitrarily following the stepped portion of the bonding surface.

Hereinafter, an example of an embodiment of the present invention will be described. However, the present invention is not limited to the following embodiments.

A method for producing a laminate for constituting an image display device according to an example of an embodiment of the present invention (referred to as “a method for producing a laminate for constituting an image display device”) is a predetermined adhesive resin composition (“present adhesive”). A transparent double-sided pressure-sensitive adhesive material from the resin composition ”, two image display device constituent members are laminated via the transparent double-sided adhesive material, and the two image display device constituent members are attached. This is a method for manufacturing a laminate for constituting an image display device (referred to as “the laminate for constituting an image display device”).
First, the “adhesive resin composition” used in the method for producing a laminate for constituting an image display device will be described.

≪This adhesive resin composition≫
This pressure-sensitive adhesive resin composition is a pressure-sensitive adhesive resin composition containing an acrylic copolymer (A), a crosslinking agent (B), and a photopolymerization initiator (C).

<Acrylic copolymer (A)>
The acrylic copolymer (A) is a graft copolymer having a macromonomer as a branch component.

(Stem component)
The trunk component of the acrylic copolymer (A) is preferably composed of a copolymer component containing a repeating unit derived from (meth) acrylic acid ester.

The glass transition temperature of the copolymer constituting the trunk component of the acrylic copolymer (A) is preferably −70 to 0 ° C.
In this case, the glass transition temperature of the copolymer component constituting the trunk component refers to the glass transition temperature of the polymer obtained by copolymerizing only the monomer component constituting the trunk component of the acrylic copolymer (A). . Specifically, it means a value calculated by the Fox formula from the glass transition temperature and the composition ratio of the polymer obtained from the homopolymer of each component of the copolymer.
In addition, the calculation formula of Fox is a calculation value calculated | required by the following formula | equation, Polymer handbook [Polymer HandBook, J.M. Brandrup, Interscience, 1989].
1 / (273 + Tg) = Σ (Wi / (273 + Tgi))
[Wherein Wi represents the weight fraction of monomer i, and Tgi represents Tg (° C.) of the homopolymer of monomer i. ]

The glass transition temperature of the copolymer component constituting the trunk component of the acrylic copolymer (A) is the flexibility of the pressure-sensitive adhesive resin composition at room temperature and the pressure-sensitive adhesive resin composition to the adherend. The glass transition temperature is −70 ° C. to 0 ° C. in order for the pressure-sensitive adhesive resin composition to obtain appropriate adhesiveness (tackiness) at room temperature because it affects the wettability of an object, that is, adhesiveness. Of these, −65 ° C. or higher or −5 ° C. or lower is preferable, and among them, −60 ° C. or higher or −10 ° C. or lower is particularly preferable.

However, even if the glass transition temperature of the copolymer component is the same temperature, the viscoelasticity can be adjusted by adjusting the molecular weight. For example, it can be made more flexible by reducing the molecular weight of the copolymer component.

Examples of the (meth) acrylic acid ester monomer contained in the main component of the acrylic copolymer (A) include 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, n-butyl acrylate, ethyl acrylate, and methyl methacrylate. And methyl acrylate. These include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, acrylic acid, methacrylic acid, glycidyl acrylate, acrylamide, N, N-dimethylacrylamide, acrylonitrile, methacrylate having hydrophilic groups and organic functional groups. Ronitrile and the like can also be used.
Various vinyl monomers such as vinyl acetate, alkyl vinyl ether, and hydroxyalkyl vinyl ether that can be copolymerized with the acrylic monomer or methacryl monomer can also be used as appropriate.

Moreover, it is preferable that the trunk component of the acrylic copolymer (A) contains a hydrophobic (meth) acrylate monomer and a hydrophilic (meth) acrylate monomer as constituent units.
If the trunk component of the acrylic copolymer (A) is composed only of a hydrophobic monomer, a tendency to wet-heat whitening is recognized. Therefore, it is preferable to introduce a hydrophilic monomer into the trunk component to prevent wet-heat whitening. .
Specifically, as the backbone component of the acrylic copolymer (A), a hydrophobic (meth) acrylate monomer, a hydrophilic (meth) acrylate monomer, and a polymerizable functional group at the end of the macromonomer are included. The copolymer component formed by random copolymerization can be mentioned.

Here, examples of the hydrophobic (meth) acrylate monomer include n-butyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, n-nonyl (meth) acrylate, n -Decyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-methylhexyl (meth) acrylate, isooctyl (meth) acrylate, isononyl (meth) acrylate, isodecyl (meth) acrylate, ethyl (meth) acrylate, n- Propyl (meth) acrylate, isopropyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyloxyethyl Examples include ru (meth) acrylate, methyl methacrylate, and vinyl acetate.

Examples of the hydrophilic (meth) acrylate monomer include methyl acrylate, (meth) acrylic acid, tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, 2- (Meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxypropyl hexahydrophthalic acid, N, N-dimethylacrylamide, hydroxyethylacrylamide, etc. Can do.

(Branch component: macromonomer)
It is important for the acrylic copolymer (A) to introduce a macromonomer as a branch component of the graft copolymer and to contain a repeating unit derived from the macromonomer.
The macromonomer is a polymer monomer having a terminal polymerizable functional group and a high molecular weight skeleton component.

The glass transition temperature (Tg) of the macromonomer is preferably higher than the glass transition temperature of the copolymer component constituting the acrylic copolymer (A).
Specifically, since the glass transition temperature (Tg) of the macromonomer affects the heat melting temperature (hot melt temperature) of the present adhesive resin composition, the glass transition temperature (Tg) of the macromonomer is 30 ° C. to 120 ° C. Preferably, the temperature is 40 ° C. or higher or 110 ° C. or lower, more preferably 50 ° C. or higher or 100 ° C. or lower.
With such a glass transition temperature (Tg), by adjusting the molecular weight, it is possible to maintain excellent processability and storage stability, and to adjust so as to hot-melt near 80 ° C.
The glass transition temperature of the macromonomer refers to the glass transition temperature of the macromonomer itself, and can be measured with a differential scanning calorimeter (DSC).

Further, at room temperature, the branch components are attracted to each other and can maintain a state where they are physically cross-linked as an adhesive resin composition, and the physical cross-linking is released by heating to an appropriate temperature. In order to obtain fluidity, it is also preferable to adjust the content of the macromonomer.
From this viewpoint, the macromonomer is preferably contained in the acrylic copolymer (A) in a proportion of 5% by mass to 30% by mass, particularly 6% by mass or more and 25% by mass or less, of which 8% by mass. It is preferable that the amount is 20% by mass or more.

The component constituting the high molecular weight skeleton of the macromonomer is preferably composed of an acrylic monomer or a vinyl monomer, and more preferably a hydrophobic monomer.
Examples of the component constituting the high molecular weight skeleton of the macromonomer include styrene, acrylonitrile, t-butylstyrene, α-methylstyrene, vinyltoluene, methyl methacrylate, 2-phenoxyethyl methacrylate, 3,5,5-trimethylcyclohexane acrylate. P-cumylphenol EO modified acrylate, isobornyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl methacrylate, stearyl acrylate, stearyl methacrylate, cetyl acrylate, cetyl methacrylate, phenoxyethyl methacrylate, behenyl Examples include acrylate, behenyl methacrylate, and benzyl methacrylate.
Among the components, a monomer having a glass transition temperature of 30 ° C. to 120 ° C. when the component constituting the high molecular weight skeleton of the macromonomer is a homopolymer is more preferable. Specifically, examples of the monomer include methyl methacrylate, 3,5,5-trimethylcyclohexane acrylate, isobornyl acrylate, and dicyclopentanyl acrylate.
Further, among the components, when the component constituting the high molecular weight skeleton of the macromonomer has crystallinity, the monomer has a crystal melting temperature of 30 ° C. to 120 ° C. when the component is a homopolymer. Is more preferable. Specifically, examples of the monomer include stearyl acrylate, stearyl methacrylate, cetyl acrylate, cetyl methacrylate, behenyl acrylate, and behenyl methacrylate.
When constituting the high molecular weight skeleton of the macromonomer, one of these monomers may be polymerized and used alone, or a plurality of these monomers may be copolymerized and used.

Examples of the terminal polymerizable functional group of the macromonomer include a methacryloyl group, an acryloyl group, and a vinyl group.

(Physical properties of acrylic copolymer (A))
The acrylic copolymer (A) preferably has a complex viscosity of 100 to 800 Pa · s, more preferably 150 to 700 Pa · s, more preferably 170 to 600 Pa · s at a temperature of 130 ° C. and a frequency of 0.02 Hz. preferable.
The complex viscosity at a temperature of 130 ° C. of the acrylic copolymer (A) affects the fluidity of the pressure-sensitive adhesive resin composition when the transparent double-sided pressure-sensitive adhesive material is hot-melted. If it is ˜800 Pa · s, excellent hot melt suitability can be imparted.

In order to adjust the complex viscosity of the acrylic copolymer (A) to the above range, for example, adjusting the glass transition temperature of the copolymer component constituting the trunk component of the acrylic copolymer (A) is mentioned. It is done. Preferably, the viscosity is adjusted to −70 ° C. to 0 ° C., particularly −65 ° C. or higher or −5 ° C. or lower, and in particular, −60 ° C. or higher or −10 ° C. or lower, and the molecular weight of the copolymer component is adjusted to improve viscoelasticity. The method of adjusting can be mentioned. However, it is not limited to this method.

<Crosslinking agent (B)>
After the image display device constituent members are bonded and integrated, the cross-linking agent (B) is cross-linked in the adhesive material, so that the sheet exhibits high cohesion in a high temperature environment instead of losing hot melt properties. Excellent foaming reliability can be obtained.

As such a crosslinking agent (B), for example, an epoxy crosslinking agent, an isocyanate crosslinking agent, an oxetane compound, a silane compound, an acrylic compound, or the like can be appropriately selected. Especially, the polyfunctional (meth) acrylate which has 3 or more of (meth) acryloyl groups is preferable at the point of reactivity or the intensity | strength of the hardened | cured material obtained.

Examples of such polyfunctional (meth) acrylates include 1,4-butanediol di (meth) acrylate, glycerin di (meth) acrylate, glycerin glycidyl ether di (meth) acrylate, and 1,6-hexanediol di (meth) acrylate. ) Acrylate, 1,9-nonanediol di (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, bisphenol A polyethoxydi (meth) acrylate, bisphenol A polypropoxy di (meth) acrylate, bisphenol F polyethoxydi (meth) Acrylate, ethylene glycol di (meth) acrylate, trimethylolpropane trioxyethyl (meth) acrylate, ε-caprolactone modified tris (2-hydroxyethyl) isocyanurate tri (meta) ) Acrylate, pentaerythritol tri (meth) acrylate, propoxylated pentaerythritol tri (meth) acrylate, ethoxylated pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, propoxylated pentaerythritol tetra (meth) acrylate, ethoxy Pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, polyethylene glycol di (meth) acrylate, tris (acryloxyethyl) isocyanurate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) Acrylate, dipentaerythritol penta (meth) acrylate, tripentaerythritol hexa (me ) Acrylate, tripentaerythritol penta (meth) acrylate, hydroxybivalic acid neopentyl glycol di (meth) acrylate, di- (meth) acrylate of ε-caprolactone adduct of hydroxybivalic acid neopentglycol, trimethylolpropane tri ( In addition to UV-curable polyfunctional monomers such as (meth) acrylate, trimethylolpropane polyethoxytri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, polyester (meth) acrylate, epoxy (meth) acrylate, urethane ( Mention may be made of polyfunctional acrylic oligomers such as (meth) acrylates and polyether (meth) acrylates.

Among the examples mentioned above, a polyfunctional monomer or oligomer containing a polar functional group such as a hydroxyl group is preferable from the viewpoint of improving the adhesion to the adherend and the effect of suppressing the heat and whitening.
Among these, it is preferable to use polyfunctional (meth) acrylic acid ester having a hydroxyl group.
Therefore, from the viewpoint of preventing wet heat whitening, it is preferable to contain a hydrophobic acrylate monomer and a hydrophilic acrylate monomer as a backbone component of the acrylic copolymer (A), that is, the graft copolymer. Furthermore, it is preferable to use a polyfunctional (meth) acrylic acid ester having a hydroxyl group as the crosslinking agent (B).

The content of the crosslinking agent (B) is not particularly limited. As a guideline, the ratio of 0.5 to 20 parts by weight, particularly 1 part or more or 15 parts by weight or less, particularly 2 parts or more or 10 parts by weight or less based on 100 parts by weight of the acrylic copolymer (A). Is preferred.
By containing a crosslinking agent (B) in the said range, the shape stability of this adhesive material in an uncrosslinked state and the anti-foaming reliability in the adhesive material after bridge | crosslinking can be made compatible. However, this range may be exceeded in balance with other elements.

<Photopolymerization initiator (C)>
The photopolymerization initiator (C) functions as a reaction initiation assistant in the crosslinking reaction of the aforementioned crosslinking agent (B). As the photopolymerization initiator, those currently known can be used as appropriate. Among these, a photopolymerization initiator that is sensitive to ultraviolet rays having a wavelength of 380 nm or less is preferable from the viewpoint of easy control of the crosslinking reaction.

Photopolymerization initiators are roughly classified into two types depending on the radical generation mechanism, a cleavage type photopolymerization initiator that can cleave and decompose a single bond of the photopolymerization initiator itself, and a photoexcited initiator. And a hydrogen donor in the system form an exciplex and can be roughly classified into a hydrogen abstraction type photopolymerization initiator that can transfer hydrogen of the hydrogen donor.

Among these, the cleavage type photopolymerization initiator is decomposed when a radical is generated by light irradiation to be another compound, and once excited, it does not function as a reaction initiator. For this reason, it does not remain as an active species in the pressure-sensitive adhesive after the crosslinking reaction is completed, and it is not likely to cause unexpected light degradation or the like in the pressure-sensitive adhesive, which is preferable.
On the other hand, a hydrogen abstraction type photopolymerization initiator does not generate a decomposition product such as a cleavage type photopolymerization initiator during radical generation reaction by irradiation of active energy rays such as ultraviolet rays, so that it is difficult to become a volatile component after completion of the reaction. This is useful in that damage to the body can be reduced.

Examples of the cleavage type photoinitiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1- ON, 1- (4- (2-hydroxyethoxy) phenyl) -2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1- [4- {4- (2-hydroxy-2 -Methyl-propionyl) benzyl} phenyl] -2-methyl-propan-1-one, oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone), phenylglyoxylic Methyl acid, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1- ON, 2- (dimethylamino) -2-[( 4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyl Examples thereof include diphenylphosphine oxide and derivatives thereof.

Examples of the hydrogen abstraction type photoinitiator include benzophenone, 4-methyl-benzophenone, 2,4,6-trimethylbenzophenone, 4-phenylbenzophenone, 3,3′-dimethyl-4-methoxybenzophenone, 2-benzoylbenzoic acid. Methyl, methyl benzoylformate, bis (2-phenyl-2-oxoacetic acid) oxybisethylene, 4- (1,3-acryloyl-1,4,7,10,13-pentaoxotridecyl) benzophenone, thioxanthone, Examples thereof include 2-chlorothioxanthone, 3-methylthioxanthone, 2,4-dimethylthioxanthone, 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 2-aminoanthraquinone and derivatives thereof.
However, the photopolymerization initiator is not limited to the substances listed above. In the present adhesive resin composition, any one of a cleavage type photopolymerization initiator and a hydrogen abstraction type photopolymerization initiator may be used, or a combination of both may be used.

The content of the photopolymerization initiator (C) is not particularly limited. As a guideline, 0.1 to 10 parts by weight, particularly 0.5 parts by weight or more and 5 parts by weight or less, and 1 part by weight or more or 3 parts by weight or less based on 100 parts by weight of the acrylic copolymer (A). It is preferable to contain in the ratio.
By setting the content of the photopolymerization initiator (C) in the above range, an appropriate reaction sensitivity with respect to the active energy ray can be obtained.

<Other components (D)>
This adhesive resin composition may contain the well-known component mix | blended with the normal adhesive resin composition as components other than the above. For example, as necessary, various additives such as a tackifier resin, an antioxidant, a light stabilizer, a metal deactivator, an anti-aging agent, and a hygroscopic agent can be appropriately contained.
Moreover, you may contain reaction catalyst (A tertiary amine type compound, a quaternary ammonium type compound, a lauric acid tin compound, etc.) suitably as needed.

<Method for Producing Laminate for Configuring Image Display Device>
This method for producing a laminate for constituting an image display device is a production method characterized by having at least the following steps (1) to (3).
(1) The present pressure-sensitive adhesive resin composition is prepared, and a single-layer or multilayer transparent double-sided pressure-sensitive adhesive material (referred to as “the present pressure-sensitive adhesive material”) having a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive resin composition is formed into a sheet. The step of forming into (referred to as “step (1)”).
(2) A step of attaching and laminating two image display device constituent members via the present adhesive material (referred to as “step (2)”).
(3) A step of irradiating the adhesive layer of the present adhesive material with active energy rays from the outside of at least one of the image display device constituent members, cross-linking the adhesive layer, and bonding the two image display device constituent members ( (Referred to as “step (3)”).

In addition, since the manufacturing method of the laminate for constituting the image display device only needs to include at least the following steps (1) to (3), other steps are added or other steps are performed between the steps. It is possible to insert.

<Step (1)>
In step (1), the pressure-sensitive adhesive resin composition is prepared, and a single-layer or multilayer uncrosslinked transparent double-sided pressure-sensitive adhesive material (this pressure-sensitive adhesive material) provided with a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive resin composition is formed into a sheet. To form.
As a method for forming the pressure-sensitive adhesive resin composition into a sheet, a currently known method can be arbitrarily adopted.
At this time, the pressure-sensitive adhesive resin composition is formed into a single-layer or multilayer sheet on the release film to produce a single-layer or multilayer transparent double-sided pressure-sensitive adhesive material having an adhesive layer. Good.
Further, the pressure-sensitive adhesive resin composition is molded into a single-layer or multilayer sheet on the image display device constituent member, and the single-layer or multi-layer transparent provided with the adhesive layer on the image display device constituent member. You may make it produce a double-sided adhesive material.

When the adhesive material is a multilayer transparent double-sided adhesive material, it is preferable that the outermost layer has both uneven followability and foam resistance reliability as in the case of the single layer. It is preferable to mold using an adhesive resin composition.

On the other hand, since the intermediate layer does not contribute to adhesion with the image display device constituent member, it does not impair the transparency, and has a light transmittance that does not hinder the secondary curing reaction of the outermost layer, and has a cutting property. In addition, it preferably has a property of improving handling properties.
If the kind of base polymer which forms an intermediate | middle layer is transparent resin, it will not specifically limit. The base polymer forming the intermediate layer may be the same resin as the base polymer of the outermost layer or a different resin. Among these, it is preferable to use the same acrylic resin as the base polymer of the outermost layer from the viewpoints of ensuring transparency and ease of production, and preventing light refraction at the lamination boundary surface.
The intermediate layer and other resin layers may or may not have active energy ray curability. For example, it may be formed so as to be cured by ultraviolet crosslinking or may be formed so as to be cured by heat. Further, it may be formed so as not to be post-cured. However, in consideration of adhesion to the outermost layer, etc., it is preferably formed so as to be post-cured, and particularly preferably formed so as to be UV-crosslinked.
In that case, since light transmittance will fall, if content of a crosslinking initiator increases, it is preferable to contain a ultraviolet-ray crosslinking agent by the content rate lower than the content rate in the outer layer of the crosslinking initiator in an intermediate | middle layer.

When the present adhesive material is a multi-layer transparent double-sided adhesive material, as a laminated structure, specifically, a two-type two-layer structure in which the present adhesive resin composition and another adhesive resin composition are laminated, Two kinds of three-layer structure in which the present adhesive resin composition is arranged on the front and back through an intermediate resin layer, the present adhesive resin composition, an intermediate resin composition, and another adhesive resin composition are laminated in this order. 3 types, 3 layers structure etc. which are formed can be mentioned.
Further, the pressure-sensitive adhesive resin composition and another pressure-sensitive adhesive resin composition are formed into a sheet shape on different release films or image display device constituent members, and the pressure-sensitive adhesive material is obtained by laminating both pressure-sensitive adhesive surfaces. Alternatively, the pressure-sensitive adhesive resin composition, the intermediate resin composition, and the pressure-sensitive adhesive resin composition may be coextruded in this order to obtain a two-kind three-layer pressure-sensitive adhesive material. Alternatively, the pressure-sensitive adhesive material may be obtained by laminating the pressure-sensitive adhesive resin composition or another pressure-sensitive adhesive resin composition on the front and back surfaces of the intermediate resin layer.
However, it is not limited to these manufacturing methods.
In the step (1), the transparent double-sided pressure-sensitive adhesive material is in an uncrosslinked state.

(thickness)
The total thickness of the present adhesive material is preferably 50 μm to 1 mm, more preferably 75 μm or more or 500 μm or less.
If the total thickness of the pressure-sensitive adhesive material is 50 μm or more, it is possible to follow unevenness such as a high printing level difference, and if it is 1 mm or less, the demand for thinning can be met.
Furthermore, the printing thickness of the peripheral concealing layer in the conventional image display device is higher, specifically, from the viewpoint of filling up to a level difference of about 80 μm, the total thickness of the present adhesive material is more preferably 75 μm or more. More preferably, it is 100 μm or more. On the other hand, from the viewpoint of meeting the demand for thinning, it is preferably 500 μm or less, more preferably 350 μm or less.

In the case of a multilayer structure, the ratio of the thickness of each outermost layer to the thickness of the intermediate layer is preferably 1: 1 to 1:20, and more preferably 1: 2 to 1:10.
If the thickness of the intermediate layer is within the above range, the contribution of the thickness of the pressure-sensitive adhesive layer in the laminate is not too large, and it is preferable that the workability relating to cutting and handling is not deteriorated because it is too flexible.
In addition, if the outermost layer is in the above range, it is preferable because the adhesion to the adherend and the wettability can be maintained without being inferior in conformity to unevenness and a bent surface.

(Features of this adhesive)
The present pressure-sensitive adhesive material, both of a single layer and a multilayer structure, is transparent, can maintain a shape in a sheet shape in a normal state, and has adhesiveness. In addition, by heating the pressure-sensitive adhesive material and fluidizing the pressure-sensitive adhesive layer, it is possible to fill in every corner following the stepped portion of the bonding surface without leaving any distortion in the pressure-sensitive adhesive material. By cross-linking, it is possible to maintain foam resistance under high temperature and high humidity environment.
Therefore, using this pressure-sensitive adhesive material, the following steps (2) to (3) can be realized to produce the laminate for constituting the image display device.

Transparency of the adhesive material is determined by shaping the adhesive resin composition into a 150 μm thick sheet between soda lime glass (0.5 mm thickness) and a cycloolefin polymer film (100 μm thickness). The haze (JIS K7136) of the sandwiched laminate can be made less than 10%, especially 5% or less, especially 2% or less.

For transparency after wet heat storage, the pressure-sensitive adhesive resin composition is shaped into a sheet having a thickness of 150 μm, soda lime glass (0.5 mm thickness) and cycloolefin polymer film (100 μm thickness). After being cured by irradiating with ultraviolet rays, the laminate sandwiched between the layers was stored in a moist heat environment of 65 ° C. and 90% RH for 100 hours, and then stored for 2 hours in a room temperature environment of 23 ° C. and 50% RH. Haze (JIS K7136) can be less than 10%, especially 5% or less, especially 2% or less.

In addition, this adhesive material was bonded to a SUS plate with an area of 20 mm × 20 mm in a holding power measurement according to JIS-Z-0237 (ISO 29863), and a load of 500 gf was applied in an atmosphere of 40 ° C. The drop time can be 20 minutes or more, and the drop time when a load of 500 gf is applied in an atmosphere at 70 ° C. can be less than 5 minutes.
At this time, the dropping time in an atmosphere of 40 ° C. is more preferably 40 minutes or longer, and more preferably 60 minutes or longer.
On the other hand, the dropping time in an atmosphere at 70 ° C. is more preferably 3 minutes or less, and more preferably 2 minutes or less.

<Step (2)>
In the step (2), two image display device constituent members can be adhered and laminated through the present adhesive material.

Since the acrylic copolymer (A) that is the base polymer of the present adhesive material is a graft copolymer containing a macromonomer as a branch component, the macromonomer aggregates in a normal state, that is, at room temperature. A physical cross-linked structure can be formed, and excellent storage stability and cutting processability can be imparted to the present adhesive material.
In addition, since the acrylic copolymer (A) has a complex viscosity of 100 to 800 Pa · s at a temperature of 130 ° C. and a frequency of 0.02 Hz, it enjoys excellent workability when used as a hot melt sheet during bonding. be able to.

Thus, in the step (2), two image display device constituent members can be adhered and laminated through the present adhesive material. In this way, it is possible to obtain a degree of adhesiveness that can be easily attached by simply pressing the present adhesive material against the adherend. Therefore, it is easy to position the adhesive material and it is very convenient for work.

In addition, since the present adhesive material is excellent in shape retention and can be processed into an arbitrary shape in advance, an image display device constituent member for laminating the present adhesive material formed on a release film It can also be cut in advance according to the dimensions.
The cutting method at this time is generally punched with a Thomson blade, cut with a super cutter or laser, and half-cuts leaving either the front or back release film in a frame shape so that the release film can be easily peeled off. Is more preferable.
Also in the step (2), the present adhesive material, that is, the transparent double-sided adhesive material is in an uncrosslinked state.

<Step (3)>
In step (3), the adhesive layer of the present adhesive material is irradiated with active energy rays from the outside of at least one of the image display device constituent members, the adhesive layer is crosslinked, and the two image display device constituent members are bonded. Thus, the laminate for constituting the image display device can be manufactured.

Since the present adhesive material contains a crosslinking agent (B) and a photopolymerization initiator (C), the adhesive layer of the present adhesive material is irradiated with active energy rays, and the adhesive layer is crosslinked and cured. The two image display device constituent members can be firmly attached.

In this case, as the active energy ray, an energy ray that sensitizes the polymerization initiator, such as a heat ray, an X-ray, an electron beam, an ultraviolet ray, or a visible ray, may be irradiated. Among them, it is preferable to irradiate ultraviolet rays, particularly ultraviolet rays having a wavelength of 380 nm or less, from the viewpoints of suppressing damage to the image display device constituent members and facilitating reaction control.
There are no particular restrictions on the UV irradiation conditions. For example, it is preferable to irradiate such that the cumulative amount of ultraviolet light reaching the adhesive material is 500 to 5000 mJ / cm ^{2 at} a wavelength of 365 nm. This is from the viewpoint of sufficiently promoting the crosslinking reaction while maintaining workability.
However, when the constituent elements of the image display device that are interposed when irradiating ultraviolet rays block the light beam having the above wavelength, the type of energy rays to which the adhesive material is sensitive in accordance with the interposed member is the type of polymerization initiator. It is preferable to adjust as appropriate.

In this step (3), the pressure-sensitive adhesive layer after irradiation of the pressure-sensitive adhesive layer, that is, the transparent double-sided pressure-sensitive adhesive material that forms the pressure-sensitive adhesive layer, is measured in holding power according to JIS-Z-0237 (ISO 29863). The deviation length after 30 minutes when a load of 500 gf is applied in an atmosphere of 40 ° C. and 70 ° C. can be made less than 1 mm.
At this time, the shift length is more preferably 0.8 mm or less, and more preferably 0.5 mm or less.

<Other processes>
Between the step (2) and the step (3), a step of heating and melting the pressure-sensitive adhesive layer of the transparent double-sided pressure-sensitive adhesive material by heating the laminate obtained in the step (2) may be inserted. . That is, the adhesive layer of the present adhesive material may be heated and melted (hot melted) by heating the laminate adhered in the step (2).

When the adhesive is heated, the aggregation of the macromonomers is released, the physical cross-linking structure is eliminated, and high fluidity can be exhibited. Therefore, if there are irregularities such as printing steps on the wearing surface, when laminating two image display device components, this adhesive material is heated to flow (hot melt) to follow the irregularities of the adhesive material. And wettability to the adherend are increased, and the members can be more firmly integrated without leaving any distortion.

At this time, it is preferable to perform hot melt by heating to 60 to 100 ° C. If it is 60 degreeC or more, the fluidity | liquidity of an adhesive material can fully be provided and an adhesive resin composition can fully be filled to an uneven | corrugated | grooved part. On the other hand, if it is 100 ° C. or less, not only can the thermal damage to the image display device constituting member to be adhered be suppressed, but also the adhesive material flows too much and the adhesive resin composition is protruded and crushed. Can also be prevented.
From such a viewpoint, the hot melt temperature is preferably 60 to 100 ° C., more preferably 62 ° C. or more and 95 ° C. or less, and particularly preferably 65 ° C. or more and 90 ° C. or less.

<Laminated body for configuring the present image display device>
Examples of the laminate for constituting the image display device include a plane using an image display panel such as an LCD, PDP, or EL, such as a personal computer, a mobile terminal (PDA), a game machine, a television (TV), a car navigation system, a touch panel, and a pen tablet. The structural member of a type | mold image display apparatus can be mentioned.
Among them, there can be mentioned a laminate for constituting an image display device having a construction in which these image display panels and a transparent panel or a film member such as a protective panel or a touch panel are bonded together with an adhesive material.

For example, in a display screen of a mobile phone, a configuration in which a surface protection panel is laminated on a functional film such as a touch panel film via a sheet-like adhesive material is employed. At this time, a concealing printing portion (thickness of about 5 μm to 80 μm) is attached to the back surface of the protective panel, and the adhesive is provided even in the corner of the step portion formed at the edge of the concealing printing portion. If the liquid does not enter sufficiently, bubbles remain and the visibility of the screen decreases. In addition, the film member may be bent in the vicinity of the step, resulting in poor appearance, or residual strain due to the bending of the film may be a starting point, and foaming or peeling may occur between the stacked members.
This pressure-sensitive adhesive material can be stuck without filling up every corner of the step and leaving bubbles even if there is a step of about 30 to 80 μm as well as a step of about 5 to 30 μm. Moreover, even if one of the adherends is a flexible film member, it is possible to smooth the surface without distortion by hot-melting the adhesive material. The members can be bonded and integrated without causing deformation. Furthermore, by cross-linking the adhesive material after bonding, the adhesive material can maintain high cohesive force without flowing even under a high temperature environment of, for example, about 85 ° C., so that foaming reliability can be obtained.

In general, “sheet” refers to a product that is thin by definition in JIS, and whose thickness is small and flat for the length and width. In general, “film” is compared to the length and width. It is a thin flat product whose thickness is extremely small and whose maximum thickness is arbitrarily limited, and is usually supplied in the form of a roll (Japanese Industrial Standard JIS K6900). However, since the boundary between the sheet and the film is not clear and it is not necessary to distinguish the two in terms of the present invention, in the present invention, even when the term “film” is used, the term “sheet” is included and the term “sheet” is used. In some cases, “film” is included.
In addition, the expression “panel” such as an image display panel and a protection panel includes a plate, a sheet, and a film.
Further, in the present invention, “sticking” refers to a state in which the adherend is fixed by the self-adhesive property of the adhesive material, that is, the adhesive material is in an uncrosslinked state, for example, temporarily fixing the adherend. It includes a state and a state where the adherend is fixed so as to be peelable. On the other hand, “adhesion” refers to a state in which the adherend is fixed in a state where the pressure-sensitive adhesive is chemically or physically changed by crosslinking the pressure-sensitive adhesive. For example, it is high at the interface with the adherend. This includes a state in which a bonding force is expressed and a case where the adherend is fixed in a state in which peeling is difficult.

In the present specification, when “X to Y” (X and Y are arbitrary numbers) is described, it means “preferably greater than X” or “preferably,” with the meaning of “X to Y” unless otherwise specified. The meaning of “smaller than Y” is also included.
Further, when described as “X or more” (X is an arbitrary number), it means “preferably larger than X” unless otherwise specified, and described as “Y or less” (Y is an arbitrary number). In the case, unless otherwise specified, the meaning of “preferably smaller than Y” is also included.

Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples. However, the present invention is not limited to these.

[Example 1]
As the acrylic copolymer (A), an acrylic ester copolymer obtained by random copolymerization of 15 parts by weight of a polymethyl methacrylate macromonomer having a number average molecular weight of 2400, 81 parts by weight of butyl acrylate, and 4 parts by weight of acrylic acid. (A-1) 1 kg (weight average molecular weight 230,000), 100 g of trimethylolpropane epoxy acrylate (EA5321 Shin-Nakamura Chemical Co., Ltd.) (B-1) as a crosslinking agent (B), a photopolymerization initiator ( Diphenyl-2,4,6-trimethylbenzoylphosphine oxide (manufactured by Omnirad TPO IGM) (C-1) (C-1) as C) was uniformly mixed to prepare an adhesive resin composition.
A laminator was sandwiched between two polyethylene terephthalate films (referred to as “release films”) from which the above composition was peeled off (Diafoil MLV-V06, Mitsubishi Plastics, Inc., 100 μm thick / Diafoil MRQ, Mitsubishi Plastics, 75 μm thick) It was shaped into a sheet shape so as to have a thickness of 150 μm, and an adhesive material 1 was produced.

Evaluation glass with white printing (total light transmittance of 0%) with a width of 10 mm and a thickness of 40 μm on the periphery of soda lime glass of 60 mm × 90 mm × thickness 0.5 mm, and a printing step of 40 μm on the periphery A substrate was produced. This glass substrate for evaluation is a substitute for an image display device constituent member having a stepped portion and a flat surface portion on the bonding surface.
As a test adherend to be bonded to the glass substrate for evaluation, a polarizing plate (“NWF-KDSEGHC-ST22” manufactured by Nitto Denko Corporation) as an image display device constituent member is previously placed on a glass plate (60 × 90 mm × What was bonded to the whole surface on one side (t0.5 mm) was produced.

One release film of the pressure-sensitive adhesive material 1 was peeled off, and the exposed pressure-sensitive adhesive surface was stuck with a hand roller so as to cover the printing step portion of the glass substrate. Next, the remaining release film is peeled off, and untreated soda lime glass is press bonded under reduced pressure (absolute pressure 5 kPa) to the exposed adhesive surface, followed by autoclaving (60 ° C., gauge pressure 0.2 MPa, 20 minutes). The adhesive material 1 was irradiated with ultraviolet rays and cross-linked so that the cumulative amount of light at a wavelength of 365 nm was 2000 mJ / cm ² from the soda lime glass surface, and a laminate for constituting an image display device was produced. .

The acrylic ester copolymer (A-1) comprises a polymethyl methacrylate macromonomer as a branch component, and butyl acrylate, acrylic acid, and a polymerizable functional group at the end of the macromonomer as a trunk component. It is a graft copolymer provided with a copolymerization component formed by random copolymerization with a methacryloyl group.
The glass transition temperature of the copolymer component constituting the backbone component of the acrylate copolymer (A-1) (the glass transition temperature determined from the theoretical value of the polymer obtained by polymerizing the copolymer component) is − It was 50 ° C.
The number average molecular weight of the polymethyl methacrylate macromonomer constituting the branch component of the acrylic ester copolymer (A-1) is 2400, the glass transition temperature of the macromonomer is 60 ° C., The acrylate copolymer (A-1) contained 15% by mass.
The acrylic copolymer (A) had a complex viscosity of 260 Pa · s at a temperature of 130 ° C. and a frequency of 0.02 Hz.

[Example 2]
A sheet-like pressure-sensitive adhesive material 2 having a thickness of 150 μm was prepared in the same manner as the pressure-sensitive adhesive material 1 except that 100 g of glycerin dimethacrylate (G101P manufactured by Kyoeisha Chemical Co., Ltd.) (B-2) was used as the crosslinking agent (B).
And the laminated body for image display apparatus structure was produced similarly to Example 1 using this adhesive material 2. FIG.

[Comparative Example 1]
An adhesive material 3 was prepared using an acrylic copolymer having no macromonomer. That is, an acrylic ester copolymer (A-2) obtained by random copolymerization of 20 parts by weight of methyl methacrylate and 80 parts by weight of butyl acrylate as the acrylic copolymer (A) (weight average molecular weight 400,000) A sheet-like pressure-sensitive adhesive material 3 having a thickness of 150 μm was produced in the same manner as the pressure-sensitive adhesive material 1 except that.
And the laminated body for image display apparatus structure was produced like Example 1 using this adhesive material 3. FIG.

[Comparative Example 2]
An adhesive material 4 was produced according to Example 3 of Japanese Patent No. 4971529.
That is, an acrylic ester copolymer obtained by random copolymerization of 75 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of vinyl acetate and 5 parts by mass of acrylic acid, into 1 kg of the acrylic ester copolymer (A-3), Nonanediol diacrylate (Biscoat 260 manufactured by Osaka Organic Chemical Co., Ltd.) (B-3) 50 g as a crosslinking agent (B) and 10 g of 4-methylbenzophenone (C-3) as a photopolymerization initiator (C) were mixed and added. An agent resin composition was prepared.
It is sandwiched between two polyethylene terephthalate films (Diafoil MLV-V06, manufactured by Mitsubishi Plastics Co., Ltd., 100 μm thick / Diafoil MRQ, manufactured by Mitsubishi Plastics Co., Ltd., 75 μm thick), and the thickness is obtained using a laminator It was shaped into a sheet so as to be 150 μm. Subsequently, UV light was irradiated to the adhesive layer through the polyethylene terephthalate film so that UV light having a wavelength of 365 nm reached 1000 mJ / cm ² , and the cross-linking agent was partially reacted to prepare an adhesive material 4 (thickness 150 μm). .
And the laminated body for image display apparatus structure was produced similarly to Example 1 using this adhesive material 4. FIG.

[Comparative Example 3]
According to Example 1 of JP2013-18227A, an adhesive material 5 was produced.
That is, as an acrylic copolymer (A), 10 parts by weight of a polymethyl methacrylate macromonomer having a number average molecular weight of 6000, 16 parts by weight of butyl acrylate, 70 parts by weight of methoxyethyl acrylate, and 4 parts by weight of 2-hydroxyethyl acrylate are randomly added. Copolymerized acrylic ester copolymer (A-4) (weight average molecular weight 300,000) 1 kg, xylylene diisocyanate trimethylolpropane adduct (TD-75, manufactured by Soken Chemical Co., Ltd.) as a crosslinking agent (B) ) A pressure-sensitive adhesive resin composition consisting of 4 g (B-4) was prepared.
The pressure-sensitive adhesive resin composition was diluted with ethyl acetate to give a 50% solid concentration diluted solution, and the release-treated polyethylene terephthalate film (Diafoil MRV-V06, 100 μm thick, manufactured by Mitsubishi Plastics) had a thickness after drying. After coating and drying to 150 μm, the polyethylene terephthalate film (Diafoil MRQ thickness 75 μm, manufactured by Mitsubishi Plastics) was coated on the adhesive surface and cured at 23 ° C. and 40% humidity for 1 week. Then, the crosslinking reaction was advanced to produce a sheet-like adhesive material 5 having a thickness of 150 μm.
And using this adhesive material 5, the laminated body for image display apparatus structure was produced similarly to Example 1 except not irradiating an ultraviolet-ray.

[Evaluation]
(Retention force of adhesive material before crosslinking)
The adhesive materials 1 to 5 produced in the examples and comparative examples were cut into 40 mm × 50 mm, the release film on one side was peeled off, and the PET film (Mitsubishi Resin Diafoil S-100, thickness 38 μm) for backing was handed After back-attaching with a roller, this was cut into a strip shape having a width of 25 mm and a length of 100 mm to obtain a test piece. Next, the remaining release film was peeled off and attached to a SUS plate (120 mm × 50 mm × thickness 1.2 mm) with a hand roller so that the application area was 20 mm × 20 mm. Then, after the test piece was cured for 15 minutes in an atmosphere of 40 ° C., a weight of 500 gf (4.9 N) was attached to the test piece in a vertical direction and left standing, and then the falling time (minute) of the weight was determined. It was measured. About what did not fall within 30 minutes, the length (mm) that the sticking position of SUS and a test piece shifted | deviated below, ie, the gap | deviation amount, was measured. At this time, if the falling time of the weight is 20 minutes or more, it has sufficient holding power, suggesting that the workability and storage stability are excellent. In the table, “<0.5 mm” means that the deviation length is less than 0.5 mm and there is almost no deviation.

Further, for the adhesive materials 1 to 5 produced in the examples and comparative examples, a laminate of a SUS plate and a test piece was prepared in the same manner as in the holding force measurement. After curing for 15 minutes in an atmosphere of 70 ° C., a weight of 500 gf (4.9 N) was attached to the test piece in the vertical direction and allowed to stand for 30 minutes, and then the falling time (minute) of the weight was measured. About what did not fall within 30 minutes, the length (mm) that the sticking position of SUS and a test piece shifted | deviated below, ie, the gap | deviation amount, was measured.
At this time, if the drop time is less than 5 minutes, high fluidity is expressed by heating, suggesting that the unevenness followability and the wettability to the adherend are enhanced.

(Holding power of adhesive material after crosslinking)
For adhesive materials 1 to 5 prepared in Examples and Comparative Examples, a laminate of SUS and a test piece was prepared in the same manner as in the above holding force measurement, and then an ultraviolet ray having a wavelength of 365 nm reached 2000 mJ / cm ^{2 on the} adhesive sheet. The UV light was irradiated from the backing PET film side using a high-pressure mercury lamp while confirming the integrated light quantity with a light meter (USHIO Corporation, UNIMETER UIT250 / sensor: UVD-C365), and the light in step (3) A test piece corresponding to the cured transparent double-sided pressure-sensitive adhesive sheet was prepared.
Thereafter, the test piece was allowed to cure for 15 minutes in an atmosphere of 40 ° C. and 70 ° C., then a 4.9 N weight was attached to the test piece in a vertical direction, and the test piece was allowed to stand for 30 minutes. The length (mm) by which the sticking position was shifted downward was measured. For specimens where the test piece hardly moved and the deviation length was less than 0.5 mm, it was indicated as “<0.5 mm” in the table.
At this time, if the test piece hardly moves, the adhesive material has a high cohesive force, suggesting that the foaming reliability is excellent.

(Haze)
The pressure-sensitive adhesive surface exposed by peeling off one release film of the pressure-sensitive adhesive materials 1 to 5 was roll-bonded to soda lime glass (82 mm × 53 mm × 0.5 mm thickness). Next, the remaining release film is peeled off, a ZEONOR film (manufactured by ZEON Corporation, 100 μm thickness) is roll-bonded, and then autoclave treatment (80 ° C., gauge pressure 0.2 MPa, 20 minutes) is applied to finish and laminate. Was made.
About the said laminated body, using the haze meter (Nippon Denshoku Industries Co., Ltd. NDH5000), the haze value after 100-hour storage in the initial heat haze and the moist heat environment of 65 degreeC90% RH ("After a moist heat test of a table | surface) Haze ") was measured according to JIS K7136.

(Processability)
100 sheets of adhesives 1 to 5 were cut with a Thomson cutting machine with a 50 mm × 80 mm Thomson blade while the release film was laminated, and the shape of the edge was observed. Edge crushing and glue squeezed out, and 20 or more release film floats were evaluated as “x”, and 20 or more release films were evaluated as “◯”.

(Storage stability of adhesive material)
The cut pieces of the adhesive materials 1 to 5 produced by the above processability evaluation are laminated so as to be sandwiched between 100 mm × 100 mm × 3 mm glass plates, and a 1 kg weight is placed on the top glass plate and allowed to stand at 40 ° C. for 65 hours. I put it.
After curing, the adhesive material was crushed, and “×” indicates that the paste protruded noticeably, “S” indicates that the adhesive protruded slightly, but “○” indicates that there was no problem with practicality, and no adhesive protruded. Was judged as “◎”.

(Adhesive strength)
One release film of adhesives 1 to 5 was peeled off, and a 50 μm PET film (Mitsubishi Resin Diafoil T100 thickness 50 μm) was bonded as a backing film.
After the laminated product was cut to a length of 150 mm and a width of 10 mm, the remaining release film was peeled off and the exposed adhesive surface was roll-bonded to soda lime glass. After the autoclave treatment (80 ° C., gauge pressure 0.2 MPa, 20 minutes) is applied to the pasted product and the final product is pasted, the accumulated light quantity of 365 nm of the adhesive materials 1 to 4 becomes 2000 mJ / cm ^2. The adhesive material was cured by irradiation and cured at 23 ° C. and 50% RH for 15 hours to obtain a peel force measurement sample.
For the adhesive material 5, since the crosslinking reaction has already been completed, a post-curing treatment such as ultraviolet irradiation was not performed, and the sample was used as it was as a peeling force measurement sample.
The peeling force (N / cm) to the glass when the peeling force measurement sample was peeled at a peeling angle of 180 ° and a peeling speed of 60 mm / min in an environment of 23 ° C. and 40% RH was measured.

(Pasteability)
Soda lime glass (82 mm x 53 mm x 0.5 mm) with an adhesive surface exposed by peeling off one of the release films of the adhesive materials 1 to 5 cut in the processability evaluation and printed with a thickness of 80 µm on the periphery 5 mm. The pressure side of the adhesive material was press-pressed using a vacuum press (absolute pressure 5 kPa, temperature 80 ° C., press pressure 0.04 MPa) so that the four sides of the adhesive material were on the printing step. Next, the remaining release film is peeled off and a ZEONOR film (manufactured by Nippon Zeon Co., Ltd., 100 μm thickness) is press-bonded, then subjected to autoclaving (80 ° C., gauge pressure 0.2 MPa, 20 minutes), and finally bonded, and the laminate 1 To 5 were produced.
Visual observation of the produced laminates 1 to 5 indicates that the adhesive material does not follow in the vicinity of the printing step and bubbles remain, and “x” indicates that the film is bent near the step and unevenness due to distortion is visible. “B” and those smoothly bonded without bubbles were judged as “B”.

(Foam resistance)
The laminates 1 to 5 produced in the examples and comparative examples were visually observed after storage for 100 hours in an environment of 85 ° C. and 85% RH, and the adhesive material was deformed, foamed and peeled after the environmental test. Those that occurred were judged as “x”, and those that did not were judged as “◯”.

(Discussion)
The sheet-like pressure-sensitive adhesive materials of the examples show that the macromonomer in the acrylate copolymer contributes as an aggregating component, and as a result, exhibits high holding power even in an uncrosslinked state, and is excellent in workability and storage stability. there were. In addition, since the adhesive materials of the examples exhibit high fluidity by heating, by heating and melting at the time of bonding, not only the followability to the uneven surface is excellent, but one of the adherends is a film Even if the material has a low rigidity, it was not bent near the step, and a smooth laminate could be obtained. In addition, the adhesive is cured by irradiating with ultraviolet rays after forming the laminate, thereby obtaining a highly reliable laminate that does not peel, foam or deform even under severe environmental tests such as high temperature and high humidity. I was able to.

On the other hand, since Comparative Example 1 is a sheet-like adhesive material using an acrylate copolymer that does not contain a macromonomer, the cohesive force as an adhesive is low, and processability and storage stability cannot be obtained. It was.
Comparative Example 2 is excellent in storage stability and cutting processability because the pressure-sensitive adhesive resin composition is partially cross-linked by ultraviolet irradiation. However, when laminating the printed stepped glass and the film, the printed step is formed on the film side. As a result, not only was the unevenness caused by the transfer transferred and a smooth laminate could not be obtained, but in the vicinity of the corner where the printing steps crossed, some of the adhesive could not be filled and bubbles remained. In addition, the foaming under the high temperature and high humidity test was triggered by the distortion of the adhesive material in the vicinity of the step, resulting in poor storage stability.
In Comparative Example 3, since the crosslinking reaction of the pressure-sensitive adhesive resin composition has already been completed in the previous stage of bonding to the member, the pressure-sensitive adhesive material alone has excellent processability and storage stability, The stepped portion was not filled smoothly.

From the results of the above examples as well as the test results conducted by the inventors so far, an acrylic copolymer (A) comprising a graft copolymer having a macromonomer as a branch component, a crosslinking agent (B), When a single-layer or multilayer transparent double-sided pressure-sensitive adhesive material molded from a pressure-sensitive adhesive resin composition containing a photopolymerization initiator (C) is used, two image display device constituent members can be bonded in the same manner as in the examples. Can be considered.

Claims (15)

1. A method of manufacturing a laminate for constituting an image display device comprising a structure in which image display device constituting members are laminated via a transparent double-sided adhesive material, comprising at least the following steps (1) to (3): A method for producing a laminate for constituting an image display device.
   (1) A pressure-sensitive adhesive resin composition comprising an acrylic copolymer (A) comprising a graft copolymer having a macromonomer as a branch component, a crosslinking agent (B), and a photopolymerization initiator (C). And forming a single-layer or multilayer transparent double-sided pressure-sensitive adhesive material having a pressure-sensitive adhesive layer made of the pressure-sensitive adhesive resin composition into a sheet.
   (2) The process of sticking and laminating | stacking two image display apparatus structural members through the said transparent double-sided adhesive material.
   (3) A step of irradiating the adhesive layer of the transparent double-sided pressure-sensitive adhesive material from the outside of at least one of the image display device constituent members, crosslinking the adhesive layer, and bonding the two image display device constituent members .
2. Between the process (2) and the process (3), the laminate obtained in the process (2) is further heated to heat and melt the adhesive layer of the transparent double-sided pressure-sensitive adhesive material. The manufacturing method of the laminated body for image display apparatus structures of Claim 1.
3. 3. The step of heating and melting the pressure-sensitive adhesive layer comprises heating the laminate to a temperature range of 60 to 100 ° C. to heat and melt (hot-melt) the pressure-sensitive adhesive layer of the transparent double-sided pressure-sensitive adhesive material. A method for producing a laminate for constituting an image display device.
4. The method for producing a laminate for constituting an image display device according to any one of claims 1 to 3, wherein the transparent double-sided pressure-sensitive adhesive material in the step (1) and the step (2) is in an uncrosslinked state. .
5. In the step (1) and the step (2), the transparent double-sided pressure-sensitive adhesive material is bonded to an SUS plate at an area of 20 mm × 20 mm in a holding power measurement according to JIS-Z-0237 (ISO 29863), and 40 ° C. The drop time when a load of 500 gf is applied in an atmosphere of 5 is 20 minutes or more, and the drop time when a load of 500 gf is applied in an atmosphere of 70 ° C. is less than 5 minutes. The method for producing a laminate for constituting an image display device according to any one of claims 1 to 4.
6. In the step (3), the transparent double-sided pressure-sensitive adhesive material after cross-linking is adhered to an SUS plate at an area of 20 mm × 20 mm in a holding power measurement according to JIS-Z-0237 (ISO 29863), and 40 ° C. and 70 ° C. The method for producing a laminate for constituting an image display device according to any one of claims 1 to 5, wherein a shift length after 30 minutes when a load of 500 gf is applied in an atmosphere of less than 1 mm .
7. The production of a laminate for constituting an image display device according to any one of claims 1 to 6, wherein the acrylic copolymer (A) contains the macromonomer in a proportion of 5 to 30% by mass. Method.
8. The glass transition temperature of the macromonomer as a branch component of the acrylic copolymer (A) is higher than the glass transition temperature of the copolymer component constituting the trunk component of the acrylic copolymer (A). The method for producing a laminate for constituting an image display device according to any one of claims 1 to 7.
9. The method for producing a laminate for constituting an image display device according to any one of claims 1 to 8, wherein the macromonomer has a glass transition temperature of 30 ° C to 120 ° C.
10. The image display device according to any one of claims 1 to 9, wherein the glass transition temperature of the copolymer component constituting the trunk component of the acrylic copolymer (A) is -70 to 0 ° C. A method for producing a structural laminate.
11. 11. The image display device according to claim 1, wherein the acrylic copolymer (A) contains a hydrophobic acrylate monomer and a hydrophilic acrylate monomer as trunk components. A method for producing a structural laminate.
12. The acrylic copolymer (A) has a structure in which a hydrophobic acrylate monomer, a hydrophilic acrylate monomer, and a polymerizable functional group at the end of a macromonomer are randomly copolymerized as a trunk component. The method for producing a laminate for constituting an image display device according to any one of claims 1 to 11, wherein:
13. The method for producing a laminate for constituting an image display device according to any one of claims 1 to 12, wherein a polyfunctional monomer or oligomer containing a polar functional group is used as the crosslinking agent (B).
14. Instead of the step (1),
    A pressure-sensitive adhesive resin composition containing an acrylic copolymer (A) composed of a graft copolymer having a macromonomer as a branch component, a crosslinking agent (B), and a photopolymerization initiator (C) is used as a release film. A single layer or multilayer transparent double-sided pressure-sensitive adhesive material provided with an adhesive layer is formed on a single-layer or multilayer sheet, and
    Instead of the step (2),
    The image display device according to any one of claims 1 to 13, wherein the release film is peeled off, and two image display device constituent members are laminated by way of the transparent double-sided adhesive material. A method for producing a structural laminate.
15. Instead of the step (1),
    An adhesive resin composition containing an acrylic copolymer (A) composed of a graft copolymer having a macromonomer as a branch component, a crosslinking agent (B), and a photopolymerization initiator (C) is imaged. A single-layer or multi-layer transparent double-sided pressure-sensitive adhesive material having an adhesive layer is formed on the image display device constituent member by forming it into a single-layer or multilayer sheet on the display device constituent member. The method for producing a laminate for constituting an image display device according to any one of claims 1 to 14.