JP6880839B2 - Coating film and adhesive sheet laminate - Google Patents

Description

The present invention can be suitably used when forming 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, or the like. The present invention relates to a coating film for a sheet laminate and a coating film suitable for forming an adhesive sheet laminate.

The touch panel type image display device usually has a configuration in which a surface protection panel, a touch panel, and an image display panel (collectively, also referred to as "components for an image display device") are combined.
In recent years, the surface protection panel of a touch panel type image display device such as a smartphone or tablet terminal uses a plastic material such as an acrylic resin plate or a polycarbonate plate together with tempered glass, and the peripheral edge of the surface protection panel other than the visible opening surface. The part is printed in black. In the touch panel, a plastic film sensor is used together with the glass sensor, a member called a touch-on lens (TOR) in which the touch panel function is integrated with the surface protection panel is used, and the touch panel function is integrated in the image display panel. Members such as on-cell and in-cell are used.

In this type of image display device, in order to further improve image visibility, the gaps between the constituent members of each image display device are filled with a transparent resin such as a liquid adhesive, a thermoplastic adhesive sheet material, or an adhesive sheet material. The structure is general.
By the way, in the field of image display devices centered on mobile phones and mobile terminals, in addition to thinning and high precision, the design is diversifying, and the peripheral edge of the surface protection panel is black in a frame shape. In the past, it was common to print the concealed part of the frame, but with the diversification of designs, the frame-shaped concealed part has begun to be formed in a color other than black. When the concealing portion is formed with a color other than black, the concealing property is low, so that the height of the concealing portion, that is, the printed portion tends to be higher than that of black. Therefore, the adhesive sheet for bonding the constituent members provided with such a printing portion is required to follow a large printing step and fill every corner.
Therefore, various methods for filling the printing step have been conventionally proposed.

For example, Patent Document 1 provides a new image display device capable of closely adhering an adhesive sheet to the adherend even if the adherend surface has a step due to printing or the like. The double-sided adhesive sheet for bonding is a double-sided adhesive sheet for adhering any two adherends selected from the components for an image display device of a surface protection panel, a touch panel, and an image display panel, and at least one of the adherends. The body has a stepped portion on the adherend surface to which the double-sided adhesive sheet is adhered, and the double-sided adhesive sheet has the shape of the abutting surface to be affixed to the adherend surface follow the surface shape of the adherend surface. A double-sided adhesive sheet for an image display device is disclosed.

Further, Patent Document 2 describes a method for manufacturing a double-sided adhesive sheet for laminating any two adherends selected from a surface protection panel, a touch panel and an image display panel. A double-sided pressure-sensitive adhesive sheet for an image display device, which comprises using an pressure-sensitive adhesive composition having a gel content of less than 40% and shaping the surface shape to be the same as the uneven shape of the bonded surface of the adherend. The manufacturing method is disclosed.

International Publication No. 2014/0733316 International Publication No. 2015/174392

In recent years, in the field of image display devices centered on mobile phones and mobile terminals, further thinning and high precision are required, and adhesive sheets for bonding image display device components also have printing steps and the like. It is required that the uneven portion on the surface of the adherend can be filled with high accuracy and that the adhesive sheet does not protrude to the outside. As a countermeasure for this, as disclosed in the above-mentioned prior patent documents, it has been studied to form the surface shape of the pressure-sensitive adhesive sheet in advance along the surface shape of the adherend.

Then, in order to form the surface shape of the pressure-sensitive adhesive sheet in advance along the surface shape of the adherend, the pressure-sensitive adhesive sheet laminate in which the release sheets are laminated on both sides of the pressure-sensitive adhesive sheet is press-molded. Therefore, a method of forming an uneven shape that matches the uneven portion on the surface of the adherend is assumed.
However, as a result of actually carrying out the above method using an adhesive sheet laminate in which a normal release film is laminated on both sides of the adhesive sheet, an uneven shape that matches the uneven portion on the surface of the adherend is obtained. The problem that it is difficult to form the adhesive sheet surface with high accuracy has become clear.

Therefore, the present invention relates to an adhesive sheet laminate provided with an adhesive sheet and a coating film that is detachably laminated on one side of the adhesive sheet, and accurately adheres an uneven shape that matches the uneven portion on the surface of the adherend. An object of the present invention is to provide a coating film that can be formed on a sheet surface.

As a result of diligent studies on the above-mentioned problems, the present inventor has found that the above-mentioned problems can be easily solved by using a coating film having a specific configuration, and has completed the present invention.

That is, the gist of the present invention is a coating film coating layer on one side of the copolyester film is provided, and wherein the storage modulus at 100 ° C. E 'is not more than 1.5 × 10 9 ^Pa It exists in the coating film.

When the coating film according to the present invention is used, for example, after heating the pressure-sensitive adhesive sheet laminate, the mold is pressed against the coating film provided with the coating layer having releasability to form the uneven portion on the surface of the adherend. An uneven shape that matches the above can be formed on the surface of the adhesive sheet with high accuracy. Further, since the coating film can maintain its shape retention in a normal state, it is not only easy to handle, but also it is not too hard, so that it is possible to suppress unnecessary and unintended unevenness on the adhesive sheet. ..

It is sectional drawing which shows typically an example of the pressure-sensitive adhesive sheet laminated body which is an Example of this invention. It is a perspective view which showed one of the molds used in an Example and a comparative example. It is sectional drawing for demonstrating an example of a pressing process at the time of manufacturing a shaped adhesive sheet laminated body using an example of the pressure-sensitive adhesive sheet laminated body which is an Example of this invention. It is a perspective view which showed typically an example of the shaped adhesive sheet laminated body which is the Example of this invention.

Hereinafter, the present invention will be described in more detail.

<Copolymerized polyester film>
The copolymerized polyester film constituting the coating film of the present invention may have a single-layer structure or a laminated structure. For example, four layers other than the two-layer and three-layer structures are not exceeded. Or more layers may be used, and the number of layers is not particularly limited. Further, for example, in the case of a three-layer structure (surface layer / intermediate layer / surface layer), any one or more of the surface layer or the intermediate layer is a copolymerized polyester component, and the other layers are copolymerized. It is also possible to use a polyester component containing no component.

The copolymerized polyester film refers to a film in which a molten polyester sheet extruded by an extrusion method is cooled and then stretched as needed.

The copolymerized polyester is preferably terephthalic acid as the dicarboxylic acid component, and in addition, oxalic acid, malonic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and diphenyl ether dicarboxylic acid. One or more of known dicarboxylic acids such as acid and cyclohexanedicarboxylic acid may be contained as a copolymerization component. As the diol component, ethylene glycol is preferable, and in addition, propylene glycol, trimethylene glycol, tetramethylene glycol, hexamethylene glycol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, and neo One or more known diols such as pentyl glycol may be contained as a copolymerization component.
Of these, copolymerized polyethylene terephthalate obtained by optionally copolymerizing phthalic acid or isophthalic acid as the dicarboxylic acid component and 1,4-cyclohexanedimethanol, 1,4-butanediol, diethylene glycol or the like as the diol component is more preferable.

The content of the copolymerization component is preferably 1 mol% or more and 50 mol% or less, more preferably 3 mol% or more or 40 mol% or less, and further preferably 4 mol% or more or 30 mol% or less. When the content of the copolymerization component is 1 mol% or more, a concave shape, a convex shape, or a concave-convex shape can be formed on the surface of the pressure-sensitive adhesive sheet when laminated with the pressure-sensitive adhesive sheet. On the other hand, when it is 50 mol% or less, not only it has sufficient dimensional stability, but also the occurrence of wrinkles during processing can be sufficiently suppressed.

The melting point of the copolymerized polyester film is preferably designed to be in the range of 260 ° C. or lower, more preferably 200 to 255 ° C. When the melting point is 260 ° C. or lower, sufficient strength can be obtained even in a heat treatment at a temperature lower than the melting point of the copolymerized polyester film in the heat treatment step after stretching.

It is desirable to contain particles in the copolymerized polyester film from the viewpoint of improving film workability. The particles include inorganic particles such as calcium carbonate, magnesium carbonate, calcium sulfate, barium sulfate, lithium phosphate, magnesium phosphate, calcium phosphate, lithium fluoride, aluminum oxide, silicon oxide, and kaolin; organic particles such as acrylic resin and guanamine resin. Particles: Precipitated particles obtained by granulating the catalyst residue can be mentioned, but are not limited thereto. The particle size of these particles and the content in the copolymerized polyester film can be appropriately determined according to the purpose. The particles to be contained may be a single component, or two or more components may be used at the same time. Further, various stabilizers, lubricants, antistatic agents and the like can be added as appropriate.

The average particle size of the particles contained in the copolymerized polyester film is preferably 0.1 to 5.0 μm. When the average particle size of the particles is less than 0.1 μm, the slipperiness of the film may be insufficient and the workability may be lowered. On the other hand, if the average particle size of the particles exceeds 5.0 μm, the smoothness of the film surface may be impaired.

The content of the particles contained in the copolymerized polyester film is preferably 0.01 to 0.3% by weight. If the content of the particles is less than 0.01% by weight, the slipperiness of the film may be insufficient and the workability may be lowered. On the other hand, if the content of the particles exceeds 0.3% by weight, the smoothness of the film surface may be impaired.

The method of adding the particles to the copolymerized polyester film is not particularly limited, and a known method can be adopted. For example, it can be added at any stage in the production of polyester, but is preferably added as a slurry dispersed in ethylene glycol or the like at the stage of esterification or at the stage after the completion of the transesterification reaction and before the start of the polycondensation reaction. The condensation reaction may proceed. Further, a method of blending a slurry of particles dispersed in ethylene glycol or water with a polyester raw material using a kneading extruder with a vent, or a method of blending dried particles with a polyester raw material using a kneading extruder. It is carried out by a method, a method of precipitating particles in a polyester manufacturing process system, or the like.

The ultimate viscosity of the copolymerized polyester is usually 0.40 to 1.10 dl / g, preferably 0.45 to 0.90 dl / g, and more preferably 0.50 to 0.80 dl / g. If the ultimate viscosity is less than 0.40 dl / g, the mechanical strength of the film tends to be weak, and if the ultimate viscosity exceeds 1.10 dl / g, the melt viscosity becomes high and the extruder is overloaded. In some cases.

Next, a production example of the copolymerized polyester film will be specifically described, but the production example is not limited to the following production example.

First, a method of using the above-mentioned copolymerized polyester raw material and cooling and solidifying the molten sheet extruded from the die with a cooling roll to obtain an unstretched sheet is preferable. In this case, in order to improve the flatness of the sheet, it is necessary to improve the adhesion between the sheet and the rotary cooling drum, and the electrostatic application adhesion method and / or the liquid coating adhesion method is preferably adopted.
The next unstretched sheet is preferably stretched at least in the uniaxial direction, and more preferably biaxially stretched in the biaxial direction. For example, as biaxial stretching, in the case of sequential biaxial stretching, the unstretched sheet is stretched in one direction by a roll or tenter type stretching machine in the mechanical direction. The stretching temperature is usually 70 to 120 ° C., preferably 75 to 110 ° C., and the stretching ratio is usually 2.5 to 7.0 times, preferably 3.0 to 6.0 times. Next, the first stage is stretched in a direction perpendicular to the stretching direction (mechanical direction). The stretching temperature is usually 70 to 170 ° C., and the stretching ratio is usually 3.0 to 7.0 times, preferably 3.5 to 6.0 times. Then, the heat treatment is subsequently performed at a temperature of 150 to 270 ° C. under tension or relaxation within 30% to obtain a biaxially oriented film. In the above-mentioned biaxial stretching, a method of performing unidirectional stretching in two or more steps can also be adopted. In that case, it is preferable to finally set the stretching ratios in the two directions within the above ranges.

Further, with respect to the production of the copolymerized polyester film, simultaneous biaxial stretching can also be adopted. Simultaneous biaxial stretching is a method of simultaneously stretching and orienting the unstretched sheet in the mechanical direction and the width direction in a state where the temperature is controlled at usually 70 to 120 ° C., preferably 75 to 110 ° C. The stretch ratio is preferably 4 to 50 times, more preferably 7 to 35 times, still more preferably 10 to 25 times in terms of area ratio. Then, the heat treatment is subsequently performed at a temperature of 150 to 250 ° C. under tension or relaxation within 30% to obtain a biaxially stretched film. As for the simultaneous biaxial stretching apparatus that employs the above-mentioned stretching method, conventionally known stretching methods such as a screw method, a pantograph method, and a linear drive method can be adopted.

<Coating layer>
In the present invention, it is important to provide a coating layer on at least one side of the copolymerized polyester film. The coating layer is not particularly limited, and specific examples thereof include a release layer, an antistatic layer, an oligomer-sealing layer, an easy-adhesion layer, and a primer layer. Above all, the release layer is more preferable in producing the pressure-sensitive adhesive sheet laminate laminated with the pressure-sensitive adhesive sheet. It is also possible to combine two or more types of functional layers as described above.

As a specific example of the coating layer constituting the coating film, the release layer will be described below.

Specific examples of the type of resin used for the release layer include curable silicone resin, fluororesin, and polyolefin resin, and among them, curable silicone resin is preferable. A curable silicone resin or a type containing a curable silicone resin as a main component may be used, and modified silicone by graft polymerization with an organic resin such as urethane resin, epoxy resin or alkyd resin as long as the gist of the present invention is not impaired. A type or the like may be used.

As the type of the curable silicone resin, any curing reaction type such as addition type, condensation type, ultraviolet curable type, electron beam curable type, and solvent-free type can be used. Specific examples include KS-774, KS-775, KS-778, KS-779H, KS-847H, KS-856, X-62-2422, X-62-2461, X manufactured by Shin-Etsu Chemical Co., Ltd. -62-1387, X-62-5039, X-62-5040, KNS-3051, X-62-1496, KNS320A, KNS316, X-62-1574A / B, X-62-7052, X-62-7028A / B, X-62-7619, X-62-7213; Momentive Performance Materials YSR-3022, TPR-6700, TPR-6720, TPR-6721, TPR6500, TPR6501, UV9300, UV9425, XS56-A2775, XS56-A2982, UV9430, TPR6600, TPR6604, TPR6605; SRX357, SRX211, SD7220, SD7292, LTC750A, LTC760A, LTC303E, SP7259, BY24-468C, SP7248S , DKQ3-203, DKQ3-204, DKQ3-205, DKQ3-210 and the like. Further, a release control agent may be used in combination to adjust the release property of the release layer.

The curing conditions for forming the release layer on the copolymerized polyester film are not particularly limited. When the release layer is provided by offline coating, it is usually preferable to perform the heat treatment at 120 to 200 ° C. for 3 to 40 seconds, preferably 100 to 180 ° C. for 3 to 40 seconds as a guide. Further, if necessary, heat treatment and active energy ray irradiation such as ultraviolet irradiation may be used in combination. As the energy source for curing by irradiation with active energy rays, conventionally known devices and energy sources can be used. From coating amount (after drying) a surface of the coating of the release layer, typically, 0.005~1g / ^{m 2,} preferably from 0.005 to 0.5 / ^{m 2,} more preferably 0.01 to The range is 0.2 g / m ^2. If the coating amount (after drying) is ^{less than 0.005 g / m 2} , the stability may be less than that of coatability, and it may be difficult to obtain a uniform coating film. On the other hand, ^{if the coating is thicker than 1 g / m 2} , the coating film adhesion, curability, etc. of the release layer itself may decrease.

As a method of providing the release layer on the copolymerized polyester film, a conventionally known coating method such as a reverse gravure coat, a direct gravure coat, a roll coat, a die coat, a bar coat, and a curtain coat can be used. Regarding the coating method, there is a description example in "Coating method" (Maki Shoten, Yuji Harasaki, published in 1979).

Further, the copolymerized polyester film may be subjected to surface treatment in advance to provide a coating layer, such as corona treatment, plasma treatment, and ultraviolet irradiation treatment.

<Coating film>
The thickness of the coating film of the present invention is usually 9 μm to 250 μm, preferably 12 μm to 125 μm, and more preferably 25 μm to 75 μm.
If the thickness is less than 9 μm, the film tension becomes insufficient, which may cause problems such as easy wrinkling at the time of slitting. On the other hand, if it exceeds 250 μm, for example, the followability to a molded product having a curved surface shape may be insufficient.

The storage elastic modulus E'at 100 ° C. of the coating film of the present invention is 1.5 × 10 ⁹ Pa or less, preferably 1.0 × 10 ⁹ Pa or less. By the storage elastic modulus E 'is not more than 1.5 × 10 9 ^Pa, when formed by laminating an adhesive sheet can be formed concave, convex, or an uneven shape to the adhesive sheet surface. In order for the storage elastic modulus E'at 100 ° C. to satisfy the above range, it can be satisfied by adjusting the type and content of the copolymerization component contained in the copolymerized polyester film.
On the other hand, the lower limit is not particularly limited, ^{but is preferably 1.0 × 10 7} Pa or more, and more preferably 1.0 × 10 ⁸ Pa or more.

The shrinkage rate of the coating film of the present invention after heating at 120 ° C. for 5 minutes is 3.0% or less, preferably 2.5% or less. When the shrinkage rate is 3.0% or less, the adhesive sheet has sufficient dimensional stability, so that a concave shape, a convex shape, or an uneven shape can be formed on the surface of the adhesive sheet when laminated with the adhesive sheet. .. Further, since the generation of wrinkles is suppressed during processing, wrinkles are not transferred to the pressure-sensitive adhesive sheet, and a pressure-sensitive adhesive sheet having a sufficient appearance can be manufactured. In order for the storage elastic modulus E'at 100 ° C. to satisfy the above range, it can be satisfied by adjusting the type and content of the copolymerization component contained in the copolymerized polyester film.

Above all, the shrinkage rate in the mechanical direction (MD) after heating at 120 ° C. for 5 minutes is preferably 3.0% or less, preferably 2.5% or less. On the other hand, the lower limit is not particularly limited, but is preferably 0.1% or more, and more preferably 0.5% or more.

Further, the shrinkage rate in the direction perpendicular to the machine direction (TD) after heating at 120 ° C. for 5 minutes is preferably 1.0% or less, preferably 0.8% or less. On the other hand, as the lower limit, −1.0% or more is preferable, and −0.5% or more is more preferable.

The coating film of the present invention has an oligomer extraction amount of 1 from the surface of the coating layer after heat treatment (180 ° C., 10 minutes) from the viewpoint of preventing contamination due to adhesion of oligomers (cyclic trimers) to the mold during molding. It is preferably 0.0 × 10 ^-3 mg / cm ² or less, and more preferably 5.0 × 10 ^-4 mg / cm ² or less.
If the amount of the oligomer extracted exceeds the range, the contamination due to the adhesion of the oligomer to the mold during the molding process may become severe. As an example, in the process of continuously heat-molding many times, the deposition of precipitated oligomers promotes mold contamination, so it is important to control the amount of oligomer precipitates during heating. For the above reason, the smaller the amount of the oligomer extracted, the more preferable.

<Adhesive sheet>
The coating film of the present invention can form a concave shape, a convex shape, or a concave-convex shape on at least one surface by laminating with the pressure-sensitive adhesive sheet.

The material of the pressure-sensitive adhesive sheet is not particularly limited, and specific base resins include (meth) acrylic copolymers, urethane-based resins, silicone-based resins, and rubber.

As an example of the pressure-sensitive adhesive sheet in the present invention, a pressure-sensitive adhesive sheet using a (meth) acrylic copolymer as a base resin will be illustrated.
In this case, it is necessary to satisfy the above-mentioned viscoelastic property in the uncrosslinked state, that is, the state before photopolymerization. From this point of view, the gel fraction of the pressure-sensitive adhesive sheet is preferably 40% or less.

When the gel fraction of the pressure-sensitive adhesive sheet is 40% or less, the bonds between the molecular chains constituting the pressure-sensitive adhesive sheet are suppressed to an appropriate range, so that the bonded pressure-sensitive adhesive sheet has appropriate fluidity when formed into a laminated body. You will be able to do it.
From this point of view, the gel fraction of the pressure-sensitive adhesive sheet is preferably 40% or less, particularly preferably 20% or less, and particularly preferably 10% or less. The lower limit of the gel fraction of the adhesive sheet is not limited, and may be 0%.
The gel fraction of the above-mentioned pressure-sensitive adhesive sheet is not limited to the case where a resin composition containing a (meth) acrylic copolymer, a cross-linking agent and a photopolymerization initiator is used as a base resin, and the pressure-sensitive adhesive sheet can be used as a pressure-sensitive adhesive sheet. The same applies to the case where another resin composition is used.

((Meta) acrylic copolymer)
For the (meth) acrylic copolymer, the characteristics such as the glass transition temperature (Tg) should be appropriately adjusted according to the type, composition ratio, polymerization conditions, etc. of the acrylic monomer and methacrylic monomer used for polymerizing the copolymer. Is possible.

Examples of the acrylic monomer and methacrylic monomer used for polymerizing the acrylic acid ester polymer include 2-ethylhexyl acrylate, n-octyl acrylate, n-butyl acrylate, ethyl acrylate, and methyl methacrylate. Vinyl acetate, hydroxyethyl acrylate, acrylic acid, glycidyl acrylate, acrylamide, acrylic nitrile, methacrylic nitrile, fluorine acrylate, silicone acrylate and the like obtained by copolymerizing these with a hydrophilic group or an organic functional group can also be used.

Among the acrylic acid ester polymers, the (meth) acrylic acid alkyl ester-based copolymer is particularly preferable.
The (meth) acrylate used for forming the (meth) acrylic acid alkyl ester-based copolymer, that is, the alkyl acrylate or alkyl methacrylate component, has an alkyl group of n-octyl, isooctyl, 2-ethylhexyl, n-butyl, and the like. It is preferably one of alkyl acrylate or alkyl methacrylate which is any one of isobutyl, methyl, ethyl and isopropyl, or a mixture of two or more selected from these.

As other components, an acrylate or methacrylate having an organic functional group such as a carboxyl group, a hydroxyl group, or a glycidyl group may be copolymerized. Specifically, a monomer component in which the alkyl (meth) acrylate component and a (meth) acrylate component having an organic functional group are appropriately and selectively combined is heat-polymerized as a starting material, and the (meth) acrylic acid ester-based copolymer is used. A polymer polymer can be obtained.
Of these, one of alkyl acrylates such as iso-octyl acrylate, n-octyl acrylate, n-butyl acrylate, and 2-ethylhexyl acrylate, or a mixture of two or more selected from these, or iso-octyl acrylate, Examples thereof include those obtained by copolymerizing at least one kind of n-octyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate and the like with acrylic acid.

As the polymerization treatment using these monomers, known polymerization methods such as solution polymerization, emulsification polymerization, massive polymerization, and suspension polymerization can be adopted, and at that time, a thermal polymerization initiator or photopolymerization can be adopted depending on the polymerization method. An acrylic acid ester copolymer can be obtained by using a polymerization initiator such as an initiator.

(Acrylic copolymer)
As an example of a preferable base polymer of the pressure-sensitive adhesive sheet, an acrylic copolymer composed of a graft copolymer having a macromonomer as a branch component can be mentioned.

If the pressure-sensitive adhesive sheet is constructed using the acrylic copolymer as a base resin, the pressure-sensitive adhesive sheet can exhibit self-adhesiveness while maintaining a sheet shape at room temperature, and melts or flows when heated in an uncrosslinked state. It has melt properties, can be photocured, and after photocuring, it can exhibit excellent cohesive force and adhere.
Therefore, if an acrylic copolymer is used as the base polymer of the pressure-sensitive adhesive sheet, it exhibits adhesiveness at room temperature (20 ° C.) even in an uncrosslinked state, and is 50 to 100 ° C., more preferably 60 ° C. or higher. Alternatively, it can have the property of softening or fluidizing when heated to a temperature of 90 ° C. or lower.

The glass transition temperature of the copolymer constituting the stem component of the acrylic copolymer is preferably −70 to 0 ° C.
At this time, the glass transition temperature of the copolymer component constituting the stem component refers to the glass transition temperature of the polymer obtained by copolymerizing only the monomer component constituting the stem component of the acrylic copolymer. Specifically, it means a value calculated by the Fox calculation formula from the glass transition temperature and the composition ratio of the polymer obtained from the homopolymer of each component of the copolymer.
The Fox calculation formula is a calculation value obtained by the following formula, and is a polymer handbook [Polymer HandBook, J. et al. It can be obtained by using the value described in Brandup, Interscience, 1989].
1 / (273 + Tg) = Σ (Wi / (273 + Tgi))
[In the formula, Wi indicates the weight fraction of the monomer i, and Tgi indicates the Tg (° C.) of the homopolymer of the monomer i. ]

The glass transition temperature of the copolymer component constituting the stem component of the acrylic copolymer affects the flexibility of the pressure-sensitive adhesive sheet at room temperature and the wettability of the pressure-sensitive adhesive sheet to the adherend, that is, the adhesiveness. Therefore, in order for the adhesive sheet to obtain appropriate adhesiveness (tackiness) at room temperature, the glass transition temperature is preferably −70 ° C. to 0 ° C., particularly −65 ° C. or higher or −5 ° C. or lower. Among them, it is particularly preferable that the temperature is −60 ° C. or higher or −10 ° C. or lower.
However, even if the glass transition temperature of the copolymer component is the same, 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 stem component of the acrylic copolymer include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, and n-butyl. (Meta) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, neopentyl (meth) acrylate, hexyl (meth) acrylate , Cyclohexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, decyl ( Meta) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, behenyl (meth) acrylate, isobornyl (meth) ) Acrylate, 2-phenoxyethyl (meth) acrylate, 3,5,5-trimethylcyclohexane acrylate, p-cumylphenol EO modified (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate , Dicyclopentenyloxyethyl (meth) acrylate, benzyl (meth) acrylate and the like. These include hydroxyl group-containing (meth) acrylates such as hydroxyethyl (meth) acrylates, hydroxypropyl (meth) acrylates, hydroxybutyl (meth) acrylates, and glycerol (meth) acrylates having hydrophilic groups and organic functional groups, and (meth) acrylates. ) Acrylate, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxypropyl hexahydrophthalic acid, 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxypropylphthalic acid Acids, 2- (meth) acryloyloxyethyl maleic acid, 2- (meth) acryloyloxypropyl maleic acid, 2- (meth) acryloyloxyethyl succinic acid, 2- (meth) acryloyloxypropyl succinic acid, crotonic acid, fumal Carboxyl group-containing monomers such as acid, maleic acid, itaconic acid, monomethyl maleate, monomethyl itaconate, acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride, glycidyl (meth) acrylate, α-ethylacrylic acid. Epoxy group-containing monomers such as glycidyl and 3,4-epoxybutyl (meth) acrylic acid, amino group-containing (meth) acrylic acid ester-based monomers such as dimethylaminoethyl (meth) acrylate and diethylaminoethyl (meth) acrylate, (meth). ) Acrylate, N-t-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone acrylamide, maleic acid amide, maleimide, etc. A monomer containing an amide group, a heterocyclic basic monomer such as vinylpyrrolidone, vinylpyridine, vinylcarbazole and the like can also be used.
In addition, styrene, t-butyl styrene, α-methyl styrene, vinyl toluene, acrylonitrile, methacrylonitonyl, vinyl acetate, vinyl propionate, alkyl vinyl ether, hydroxyalkyl vinyl ether, and alkyl, which are copolymerizable with the acrylic monomer and methacrylic monomer. Various vinyl monomers such as vinyl monomers can also be used as appropriate.

Further, the stem component of the acrylic copolymer preferably contains a hydrophobic (meth) acrylate monomer and a hydrophilic (meth) acrylate monomer as constituent units.
When the stem component of the acrylic copolymer is composed of only hydrophobic monomers, there is a tendency for moist heat bleaching. Therefore, it is preferable to introduce hydrophilic monomers into the stem components to prevent moist heat bleaching.

Specifically, as a stem component of the acrylic copolymer, a hydrophobic (meth) acrylate monomer, a hydrophilic (meth) acrylate monomer, and a polymerizable functional group at the end of the macromonomer are randomly copolymerized. Examples of the copolymer component obtained from the above.

Here, examples of the hydrophobic (meth) acrylate monomer include n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, and pentyl (meth). ) Acrylate, isopentyl (meth) acrylate, neopentyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl acrylate, n-octyl acrylate, isooctyl acrylate, nonyl (meth) ) Acrylate, isononyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, lauryl (meth) acrylate, cetyl (meth) acrylate, stearyl ( Examples thereof include meta) acrylate, isostearyl (meth) acrylate, behenyl (meth) acrylate, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylicate, and methyl methacrylate.
Examples of the hydrophobic vinyl monomer include vinyl acetate, styrene, t-butyl styrene, α-methyl styrene, vinyl toluene, and alkyl vinyl monomer.

Examples of the hydrophilic (meth) acrylate monomer include methyl acrylate, (meth) acrylic acid, tetrahydrofurfuryl (meth) acrylate, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) butyl. ) Acrylate, hydroxyl group-containing (meth) acrylate such as glycerol (meth) acrylate, (meth) acrylic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) acryloyloxypropyl hexahydrophthalic acid, 2- (Meta) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxypropylphthalic acid, 2- (meth) acryloyloxyethyl maleic acid, 2- (meth) acryloyloxypropylmaleic acid, 2- (meth) acryloyl Oxyethyl succinic acid, 2- (meth) acryloyloxypropyl succinic acid, crotonic acid, fumaric acid, maleic acid, itaconic acid, monomethyl maleate, monomethyl itaconate and other carboxyl group-containing monomers, maleic anhydride, itaconic anhydride, etc. Acid anhydride group-containing monomer, glycidyl (meth) acrylate, glycidyl α-ethyl acrylate, epoxy group-containing monomer such as 3,4-epoxybutyl (meth) acrylate, alkoxy such as methoxypolyethylene glycol (meth) acrylate Examples thereof include polyalkylene glycol (meth) acrylate, N, N-dimethylacrylamide, hydroxyethylacrylamide and the like.

It is preferable that the acrylic copolymer introduces a macromonomer as a branch component of the graft copolymer and contains a repeating unit derived from the macromonomer.
The macromonomer is a polymer monomer having a polymerizable functional group at the terminal 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.
Specifically, since the glass transition temperature (Tg) of the macromonomer affects the heating and melting temperature (hot melt temperature) of the pressure-sensitive adhesive sheet, the glass transition temperature (Tg) of the macromonomer is 30 ° C. to 120 ° C. The temperature is preferably 40 ° C. or higher or 110 ° C. or lower, and more preferably 50 ° C. or higher or 100 ° C. or lower.
With such a glass transition temperature (Tg), by adjusting the molecular weight, excellent processability and storage stability can be maintained, and the temperature can be adjusted so as to hot melt at around 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, in a room temperature state, it is possible to maintain a state in which the branch components are attracted to each other and physically cross-linked as an adhesive 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 molecular weight and content of the macromonomer.
From this point of view, the macromonomer is preferably contained in the acrylic copolymer in a proportion of 5% by mass to 30% by mass, particularly 6% by mass or more or 25% by mass or less, and among them, 8% by mass or more or 20% by mass. It is preferably mass% or less.
The number average molecular weight of the macromonomer is preferably 500 or more and less than 8000, and more preferably 800 or more or less than 7500, and more preferably 1000 or more or less than 7000.
As the macromonomer, a generally produced one (for example, a macromonomer manufactured by Toagosei Co., Ltd.) can be appropriately used.

The high molecular weight skeleton component of the macromonomer is preferably composed of an acrylic polymer or a vinyl polymer.
Examples of the terminal polymerizable functional group of the macromonomer include a methacryloyl group, an acryloyl group, and a vinyl group.

(Crosslinking agent)
As the cross-linking agent, a cross-linking monomer used for cross-linking the acrylic ester polymer can be used. For example, at least one crosslinkable functional group selected from (meth) acryloyl group, epoxy group, isocyanate group, carboxyl group, hydroxyl group, carbodiimide group, oxazoline group, aziridine group, vinyl group, amino group, imino group and amide group. The cross-linking agent having the above can be mentioned, and one kind or a combination of two or more kinds may be used.
The crosslinkable functional group may be protected by a deprotectable protecting group.

Among them, a polyfunctional organic functional group having two or more organic functional groups such as a polyfunctional (meth) acrylate having two or more (meth) acryloyl groups, an isocyanate group, an epoxy group, a melamine group, a glycol group, a siloxane group, and an amino group. An organic metal compound having a metal complex such as a base resin, zinc, aluminum, sodium, zirconium, and calcium can be preferably used.

Examples of the polyfunctional (meth) acrylate include 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, glycerin di (meth) acrylate, and glycering ricidyl ether di (meth) acrylate, 1. , 6-Hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, tricyclodecanedimethanol di (meth) acrylate, bisphenol A polyethoxydi (meth) acrylate, bisphenol A polyalkoxydi (meth) Acrylate, bisphenol F polyalkoxydi (meth) acrylate, polyalkylene glycol di (meth) acrylate, trimethylpropantrioxyethyl (meth) acrylate, ε-caprolactone-modified tris (2-hydroxyethyl) isocyanurate tri (meth) acrylate , Pentaerythritol tri (meth) acrylate, propoxylated pentaerythritol tri (meth) acrylate, ethoxylated pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, propoxylated pentaerythritol tetra (meth) acrylate, ethoxylated penta Elythritol 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, trypentaerythritol hexa (meth) acrylate, tripentaerythritol penta (meth) acrylate, neopentyl glycol hydroxybivalate di (meth) acrylate, neopenglycol hydroxybivalate ε- In addition to UV-curable polyfunctional monomers such as di (meth) acrylates of caprolactone adducts, trimetylolpropantri (meth) acrylates, alkoxylated trimetylolpropantri (meth) acrylates, and ditrimethylolpropantetra (meth) acrylates. , Polyfunctional acrylic oligomers such as polyester (meth) acrylate, epoxy (meth) acrylate, urethane (meth) acrylate, and polyether (meth) acrylate.

Among the above-mentioned polyfunctional (meth) acrylic acid ester monomers, polar functional groups such as hydroxyl groups, carboxyl groups, and amide groups are among the polyfunctional (meth) acrylic acid ester monomers from the viewpoint of improving the adhesion to the adherend and the effect of suppressing moist heat bleaching. A polyfunctional monomer or oligomer containing the above is preferable. Among them, it is preferable to use a polyfunctional (meth) acrylic acid ester having a hydroxyl group or an amide group.
From the viewpoint of preventing moist heat bleaching, it is preferable to contain a hydrophobic acrylate monomer and a hydrophilic acrylate monomer as a stem component of the (meth) acrylic acid ester copolymer, for example, a graft copolymer. Furthermore, it is preferable to use a polyfunctional (meth) acrylic acid ester having a hydroxyl group as the cross-linking agent.
Further, a monofunctional or polyfunctional (meth) acrylic acid ester that reacts with a cross-linking agent may be further added in order to adjust the effects such as adhesion, moisture heat resistance, and heat resistance.

The content of the cross-linking agent is 0.1 to 20 parts by mass with respect to 100 parts by mass of the (meth) acrylic copolymer from the viewpoint of balancing the flexibility and cohesive force of the pressure-sensitive adhesive composition. It is preferably 0.5 parts by mass or more or 15 parts by mass or less, and particularly preferably 1 part by mass or more or 13 parts by mass or less.

(Photopolymerization initiator)
When cross-linking an acrylic acid ester polymer, a cross-linking initiator (peroxidation initiator, photopolymerization initiator) or reaction catalyst (tertiary amine compound, quaternary ammonium compound, tin laurate compound, etc.) is appropriately used. It is effective when added.

In the case of ultraviolet irradiation cross-linking, it is preferable to add a photopolymerization initiator.
Photopolymerization initiators are roughly classified into two types according to the radical generation mechanism: a cleavage-type photopolymerization initiator capable of cleaving and decomposing a single bond of the photopolymerization initiator itself to generate radicals, and a photoexcited initiator. And the hydrogen donor in the system form an excitation complex, which is roughly classified into a hydrogen abstraction type photopolymerization initiator capable of transferring the hydrogen of the hydrogen donor.
Of these, the cleavage-type photopolymerization initiator decomposes to another compound when a radical is generated by light irradiation, and once excited, it loses its function as a reaction initiator. Therefore, when the intramolecular cleavage type is used as the photopolymerization initiator having an absorption wavelength in the visible light region, the pressure-sensitive adhesive sheet is crosslinked by light irradiation and then photoreactive light as compared with the case where the hydrogen extraction type is used. This is preferable because the polymerizable initiator remains in the pressure-sensitive adhesive composition as an unreacted residue, which is unlikely to cause an unexpected change over time or promotion of cross-linking of the pressure-sensitive adhesive sheet. Further, the coloring peculiar to the photopolymerizable initiator is also preferable because it becomes a reactive decomposition product, so that absorption in the visible light region is eliminated and a decolorizing one can be appropriately selected.
On the other hand, the hydrogen abstraction type photopolymerization initiator does not generate decomposition products like the cleaving type photopolymerization initiator during the radical generation reaction by irradiation with active energy rays such as ultraviolet rays, so that it is unlikely to become a volatile component after the reaction is completed, and the subject is covered. Damage to the body can be reduced.

Examples of the cleavage-type photopolymerization initiator include 2,2-dimethoxy-1,2-diphenylethane-1-one, 1-hydroxycyclohexylphenylketone, and 2-hydroxy-2-methyl-1-phenyl-propane-1. -On, 1- (4- (2-hydroxyethoxy) phenyl) -2-hydroxy-2-methyl-1-propane-1-one, 2-hirodoxy-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), phenylglycioxy Methyl licate, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) butane-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-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl) ethoxyphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) 2,4,4-trimethyl Examples thereof include pentylphosphine oxide and derivatives thereof.

Among these, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide and 2,4,6-trimethylbenzoyldiphenylphos are the cleavage-type photopolymerizable initiators in that they become decomposition products and decolorize after the reaction. Acylphosphine oxide-based photoinitiators such as finoxide, (2,4,6-trimethylbenzoyl) ethoxyphenylphosphine oxide, and bis (2,6-dimethoxybenzoyl) 2,4,4-trimethylpentylphosphine oxide are preferred.
Furthermore, from the compatibility with the acrylic copolymer composed of a graft copolymer having a macromonomer as a branch component, 2,4,6-trimethylbenzoyldiphenylphosphine oxide as a photopolymerization initiator (2,4) It is preferable to use 6-trimethylbenzoyl) ethoxyphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) 2,4,4-trimethylpentylphosphine oxide and the like.

The content of the photopolymerization initiator is not particularly limited. For example, 0.1 to 10 parts by mass, particularly 0.2 parts by mass or more or 5 parts by mass or less, and 0.5 parts by mass or more or 3 parts by mass or less, based on 100 parts by mass of the (meth) acrylic copolymer. It is particularly preferable to include it in a proportion. However, this range may be exceeded in balance with other factors.
The photopolymerization initiator may be used alone or in combination of two or more.

In addition to the above components, if necessary, pigments such as pigments and dyes having near-infrared absorption characteristics, tackifiers, antioxidants, antioxidants, hygroscopic agents, ultraviolet absorbers, silane coupling agents, natural products, etc. Various additives such as synthetic resins, glass fibers and glass beads can also be appropriately blended.

The thickness of the pressure-sensitive adhesive sheet is not particularly limited, but is preferably 20 μm to 500 μm, more preferably 30 μm or more or 300 μm or less, and further preferably 50 μm or more or 250 μm or less.
Within the above range, for example, a thin pressure-sensitive adhesive sheet having a thickness of 20 μm can provide a pressure-sensitive adhesive sheet having excellent print step followability. Further, in a thick pressure-sensitive adhesive sheet having a thickness of 500 μm, the amount corresponding to the printing step is formed in advance, so that it is possible to suppress the overflow of the pressure-sensitive adhesive composition at the time of bonding.

(Manufacturing method of adhesive sheet laminate)
As an example of the method for producing the pressure-sensitive adhesive sheet laminate, for example, a method in which the pressure-sensitive adhesive sheet is sandwiched between two coating films and a laminator is used to form the pressure-sensitive adhesive sheet can be mentioned. Further, as another method, a method of applying the pressure-sensitive adhesive composition to the coating film to form a pressure-sensitive adhesive sheet can be mentioned. However, it is not limited to such a manufacturing method.
Examples of the method for applying the pressure-sensitive adhesive composition include conventionally known coating methods such as reverse roll coating, gravure coating, bar coating, and doctor blade coating.

[Excipient adhesive sheet laminate]
Using the pressure-sensitive adhesive sheet laminate, a shaped pressure-sensitive adhesive sheet laminate in which an uneven shape is formed on the surface of the pressure-sensitive adhesive sheet can be produced as follows.

As shown in FIG. 4, the shaped adhesive sheet laminate includes an adhesive sheet, a coating film that is peelably laminated on one side of the front and back sides of the pressure-sensitive adhesive sheet, and a peelable layer on the other side of the front and back sides of the pressure-sensitive adhesive sheet. With a coating film made of
The adhesive sheet has a concave, convex, or uneven shape on one surface, and the other surface is a flat surface.
The coating film is in close contact with the adhesive sheet, has concave portions, convex portions, or uneven portions, and has concave or convex portions or concave portions that match the surface of the adhesive sheet on the back surface of the coating film, in other words, have irregularities to be fitted. Or with unevenness
The other coating film may have a structure composed of a flat surface along the surface of the pressure-sensitive adhesive sheet.

As shown in FIG. 3, the shaped pressure-sensitive adhesive sheet laminate having such a configuration is obtained by press-molding, vacuum forming, vacuum forming or roll-molding the pressure-sensitive adhesive sheet laminate with respect to the pressure-sensitive adhesive sheet laminate. It can be manufactured by integrally shaping the uneven shape.
By manufacturing in this way, the surface uneven portion of the pressure-sensitive adhesive sheet and the surface uneven portion of the coating film can be made to have irregularities corresponding to the same portions.

The pressure-sensitive adhesive sheet can be used as, for example, a double-sided pressure-sensitive adhesive sheet for bonding two image display device constituent members (each also referred to as an "adhesive body") constituting the image display device.
That is, the surface uneven portion of the adhesive sheet coincides with the concave or convex portion or the uneven portion (referred to as "adhesive body surface uneven portion") on the bonding surface (also referred to as "bonding surface") of the adherend. As such, it can preferably be formed into the same contour shape. Therefore, the surface uneven portion of the pressure-sensitive adhesive sheet in the shaped adhesive sheet laminate can be fitted to the surface uneven portion of the adherend in the image display device constituent member as the adherend.

Here, as the image display device, for example, a smartphone or tablet provided with a liquid crystal display device (LCD), an organic EL display device (OLED), an electronic paper, a micro electromechanical system (MEMS) display, a plasma display (PDP), or the like. Examples include terminals, mobile phones, televisions, game machines, personal computers, car navigation systems, ATMs, and fish finder. However, it is not limited to these.
The image display device constituent member as an adherend is a member that constitutes these image display devices, and examples thereof include a surface protection panel, a touch panel, and an image display panel. 1 can be used, for example, to bond any two adherends selected from the surface protection panel, the touch panel and the image display panel. For example, it can be used to bond the surface protection panel and the touch panel, or the touch panel and the image display panel. However, the adherend is not limited to these.

<Manufacturing method>
Here, the details of the method for producing the pressure-sensitive adhesive sheet laminate of the present invention will be described.

As described above, as shown in FIG. 3, the pressure-sensitive adhesive sheet laminate can be manufactured by heating and molding the pressure-sensitive adhesive sheet laminate to integrally shape an uneven shape with respect to the pressure-sensitive adhesive sheet laminate.
At this time, as the molding processing method, for example, press molding, vacuum forming, compressed air forming, shaping by roll, shaping by lamination and the like can be mentioned. Of these, press molding is particularly preferable from the viewpoint of moldability and processability.

A more detailed concrete example will be described.
The adhesive sheet laminate is preheated with a heater, and when it has warmed to a predetermined temperature, the adhesive sheet laminate is transported to a press molding machine, and a mold that has a concave-convex shape corresponding to the printing step shape of the adherend in advance. By performing the press working and cooling with the above, the mold shape can be transferred to one side of the pressure-sensitive adhesive sheet laminate to produce a shape-shaped pressure-sensitive adhesive sheet laminate having unevenness shaped on one side.

At this time, the preheating of the pressure-sensitive adhesive sheet laminate is preferably heated to a temperature at which the pressure-sensitive adhesive sheet is softened, specifically 70 to 120 ° C.

The material of the mold used for uneven shaping is not particularly limited. For example, resin-based materials such as silicone resin and fluororesin, metal-based materials such as stainless steel and aluminum, and the like can be mentioned. Among them, a metal-based mold capable of controlling the temperature at the time of molding is particularly preferable because high-precision moldability is required for shaping the unevenness of the adherend.
Further, the cooling after the press working may be performed after the mold is opened, or the mold may be cooled and cooled at the same time as the press.

In the present invention, the conditions related to molding such as press pressure and press time are not particularly specified, and may be appropriately adjusted according to the dimensions and shape to be molded, the material to be used, and the like.
Further, after the molding process, it may be cut using a Thomson blade, a rotary blade or the like.

<Use>
Here, an example of the usage of the adhesive sheet laminate will be described.
In recent years, as mobile phones, smartphones, tablet terminals, and the like have become more popular, there are many cases in which the image display unit is damaged due to accidental dropping by the user. In particular, when the image display device is of the touch panel type, not only the display becomes difficult to see due to damage, but also the touch panel operation itself becomes impossible due to physical obstacles or water intrusion, or it may cause a failure. Therefore, repair, that is, repair, in which only the image display unit is replaced may be performed.
In the repair of the image display device, the adhesive sheet is also used when loading a new image display unit. Usually, repair is often performed manually by a repair worker, which requires the skill of the repair worker. That is, if the person is not an expert, when the image display unit is loaded via the adhesive sheet, air may enter the inside or the adhesive material may squeeze out.
On the other hand, if the pressure-sensitive adhesive sheet laminate of the present invention is used, a highly accurate step shape or the like can be given in advance. Therefore, for example, a step shape corresponding to the model of the image display device is given to the pressure-sensitive sheet in advance. As a result, the repair work is greatly simplified, and it becomes possible to carry out the repair work without requiring the skill of a repair worker. As described above, the pressure-sensitive adhesive sheet laminate of the present invention can be usefully used for repairing an image display device.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples as long as the gist thereof is not exceeded. Various physical properties and characteristics are measured or defined as follows.

(1) Storage elastic modulus (E')
For the obtained film, a sample of 30 mm in the longitudinal direction × 5 mm in the width direction was taken so that the longitudinal direction was the mechanical direction. Next, using a dynamic viscoelastic device (“DVA-220” manufactured by IT Measurement Control Co., Ltd.), the sample was sandwiched and fixed to a chuck set at an interval of 20 mm, and then the temperature rise rate was 10 ° C./min at room temperature to normal temperature. The storage elastic modulus was measured at a frequency of 10 Hz up to 200 ° C. From the obtained data, the storage elastic modulus at 100 ° C. was read.

(2) Heat-shrinkage rate A sample is cut into strips (15 mm width x 150 mm length) from the center position in the width direction of the obtained film so that the sample longitudinal direction is the measurement direction, and the sample is cut out in a non-tension state in an atmosphere of 120 ° C. The heat treatment was performed for 5 minutes, the length of the sample before and after the heat treatment was measured, and the heat shrinkage rate (%) of the film was calculated by the following formula. In the following formula, a is the sample length before the heat treatment, and b is the sample length after the heat treatment.
Heat shrinkage rate (%) = [(ab) / a] × 100

(3) Amount of film surface oligomer after heat treatment The obtained film was treated with a polyester film in a hot air circulation oven at 180 ° C. for 10 minutes in a nitrogen atmosphere. The surface of the polyester film after the heat treatment was brought into contact with DMF (dimethylformamide) for 3 minutes to dissolve the oligomer precipitated on the surface. For such an operation, for example, in the voluntary standard for food containers and packaging made of synthetic resin such as polyolefin, the method described in the elution instrument used for the single-sided elution method in the elution test can be adopted.
Next, the concentration of the obtained DMF was adjusted by a method such as dilution if necessary, and the mixture was supplied to liquid chromatography (Shimadzu LC-2010) to determine the amount of oligomers in the DMF, and this value was used to contact the DMF. Divided by the film area to obtain the amount of film surface oligomer (mg / cm ² ).
The amount of oligomer in DMF was determined from the peak area ratio of the standard sample peak area and the measured sample peak area (absolute calibration curve method).
The standard sample was prepared by accurately weighing the pre-prepared oligomer (cyclic trimer) and dissolving it in the accurately weighed DMF. The concentration of the standard sample is preferably in the range of 0.001 to 0.01 mg / ml.

(4) Molding Suitability As a (meth) acrylic copolymer, 15 parts by mass (18 mol%) of polymethylmethacrylate macromonomer (Tg: 105 ° C.) having a number average molecular weight of 2400 and butyl acrylate (Tg: -55 ° C.) As a cross-linking agent, 1 kg of an acrylic copolymer (weight average molecular weight 230,000) formed by randomly copolymerizing 81 parts by mass (75 mol%) of acrylic acid (Tg: 106 ° C.) and 4 parts by mass (7 mol%) of acrylic acid (Tg: 106 ° C.). 90 g of glycerin dimethacrylate (manufactured by Nichiyu Co., Ltd., product name: GMR) (b-1) and a mixture of 2,4,6-trimethylbenzophenone and 4-methylbenzophenone as a photopolymerization initiator (manufactured by Lanberti Co., Ltd., product name) : 15 g of EzaCure TZT) was uniformly mixed to prepare a resin composition to be used for the pressure-sensitive adhesive sheet.
The obtained resin composition is sandwiched between two release films obtained from the polyester fills shown in Examples and Comparative Examples from above and below (the combination of the top and bottom shall be sandwiched between the same release films), and a resin is used using a laminator. A pressure-sensitive adhesive sheet laminate was prepared by shaping the composition into a sheet so that the thickness of the composition was 100 μm. The release layer side of the polyester film was arranged so as to be in contact with the resin composition.
The obtained pressure-sensitive adhesive sheet laminate was thermoformed by the following process using a vacuum compressed air molding machine (manufactured by Daiichi Kogyo Co., Ltd., FKS-0632-20 type) to prepare a shaped adhesive sheet laminate. That is, using an IR heater preheated to 400 ° C., the surface of the adhesive sheet laminate was heated to 100 ° C., and then cooled to 25 ° C., using a molding die, under the condition of a mold clamping pressure of 8 MPa for 5 seconds. Press molding was performed to produce a shaped adhesive sheet laminate having irregularities shaped on the surface.
The polyester film of the shaped adhesive sheet laminate with irregularities is peeled off, and the heights of the concave and convex parts of the shaped adhesive sheet are measured by a non-contact method using a scanning white interference microscope and molded. The height of the body was set to h.
The height h of the convex portion of the molded body with respect to the depth of 100 μm of the mold is measured, and the transfer rate derived from the following formula is ◯, 50% or more and less than 70%, Δ, 50%. Those less than are evaluated as x.
Transfer rate (%) = h (mold height) / 100 (mold depth) x 100

(5) Appearance of adhesive layer (wrinkles)
The appearance of the pressure-sensitive adhesive layer laminate before press molding obtained by the method described in (4) was evaluated by the evaluation methods shown below.
<Evaluation method>
◯: It is laminated without wrinkles and maintains a good appearance.
X: Wrinkles are generated on the film and wrinkles are transferred to the adhesive layer, so that the film cannot be used as a product.

The method for producing the polyester raw material used in the following Examples / Comparative Examples is as follows.

(Manufacturing method of polyester A)
100 parts of dimethyl terephthalate, 70 parts of ethylene glycol, and 0.07 part of calcium acetate monohydrate were taken in a reactor, heated and heated, and methanol was distilled off to carry out a transesterification reaction. It took about four and a half hours after the reaction started. Then, the temperature was raised to 230 ° C., and the transesterification reaction was substantially completed.
Next, 0.04 part of phosphoric acid and 0.035 part of antimony trioxide were added, and the mixture was polymerized according to a conventional method. That is, the reaction temperature was gradually increased to 280 ° C., while the pressure was gradually reduced to 0.05 mmHg. After 4 hours, the reaction was terminated and chips were obtained according to a conventional method to obtain polyester A. The ultimate viscosity IV of the obtained polyester chip was 0.70 dl / g.

(Manufacturing method of polyester B)
In the above method for producing polyester A, polyester B was produced by the same method as polyester A except that terephthalic acid was 78 mol% and isophthalic acid was 22 mol% as the dicarboxylic acid unit. The ultimate viscosity IV of the obtained polyester chip was 0.70 dl / g.

(Manufacturing method of polyester C)
When producing the polyester A, 6000 ppm of amorphous silica having an average particle size of 3 μm was added to prepare the polyester C.

(Manufacturing method of polyester D)
When producing the polyester A, 6000 ppm of amorphous silica having an average particle size of 4 μm was added to prepare the polyester D.

[Example 1]
The raw materials obtained by mixing the polyesters B, A, and D at a ratio of 65% by weight, 30% by weight, and 5% by weight, respectively, were melt-extruded by a melt extruder to obtain a single-layer amorphous sheet.
Then, the sheet was co-extruded onto a cooled casting drum and cooled and solidified to obtain an unoriented sheet. Then, after stretching 3.4 times at 80 ° C. in the machine direction (longitudinal direction), it was further stretched 3.9 times at 80 ° C. in the direction perpendicular to the machine direction (horizontal direction) through a preheating step in the tenter. After biaxial stretching, heat treatment was performed at 185 ° C. for 3 seconds, and then a 6.4% relaxation treatment was performed in the width direction to obtain a polyester film having a thickness of 50 μm. The evaluation results are shown in Table 1 below.

[Example 2], [Example 3]
A polyester film was obtained in the same manner as in Example 1 except that the conditions shown in Table 1 below were changed. The evaluation results are shown in Table 1 below.

[Example 4]
The raw material in which the polyesters A and C are mixed at the ratios of 86% by weight and 14% by weight is used as the raw material for the surface layer, and the raw material in which the polyesters B and A are mixed at the ratios of 45% by weight and 55% by weight is intermediate. Used as a raw material for layers. Amorphous sheets of 2 types and 3 layers (surface layer / intermediate layer / surface layer) were obtained by melt extrusion using different melt extruders.
Then, the sheet was co-extruded onto a cooled casting drum and cooled and solidified to obtain an unoriented sheet. Then, after stretching 3.4 times at 82 ° C. in the machine direction (MD), it was further stretched 3.9 times at 110 ° C. in the direction perpendicular to the machine direction (width direction, TD) through a preheating step in the tenter. After biaxial stretching, heat treatment was performed at 210 ° C. for 3 seconds, and then a 2.4% relaxation treatment was performed in the width direction to obtain a polyester film having a thickness of 50 μm. The evaluation results are shown in Table 1 below.

[Example 5]
A polyester film was obtained in the same manner as in Example 4 except that the conditions shown in Table 1 below were changed. The evaluation results are shown in Table 1 below.

[Comparative Example 1]
A polyester film was obtained in the same manner as in Example 4 except that the conditions shown in Table 2 below were changed. The evaluation results are shown in Table 2 below.

[Comparative Example 2]
A polyester film was obtained in the same manner as in Example 1 except that the conditions shown in Table 2 below were changed. The evaluation results are shown in Table 2 below.

The coating film in the present invention is suitably used for forming 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, or the like. It is suitable for a shaped pressure-sensitive adhesive sheet laminate capable of forming, and for an pressure-sensitive adhesive sheet laminate suitable for forming a shaped pressure-sensitive adhesive sheet laminate.

Claims (5)

A pressure-sensitive adhesive sheet laminate having a structure in which a coating film having a coating layer provided on at least one side of a copolymerized polyester film is laminated on both sides of the pressure-sensitive adhesive sheet via the coating layer.
The coating film has a feature in that the storage elastic modulus at 100 ° C. E 'is not more than 1.5 × ¹⁰ 9 Pa, and shrinkage after heating for 5 minutes at 120 ° C. is not more than 3.0% Adhesive sheet laminate . The coating film is, 100 ° C. storage modulus E 'is, the pressure-sensitive adhesive sheet laminate according to claim 1 is 1.0 × ¹⁰ 8 Pa or more. The pressure-sensitive adhesive sheet laminate according to claim 1 or 2, wherein the coating film has ^{a surface oligomer amount of 1.0 × 10 -3} mg / cm ² or less after heating at 180 ° C. for 10 minutes. The pressure-sensitive adhesive sheet laminate according to any one of claims 1 to 3, wherein the coating layer is a release layer containing a curable silicone resin. The pressure-sensitive adhesive sheet laminate according to any one of claims 1 to 4, which has a concave shape, a convex shape, or a concave-convex shape on at least one surface of the pressure-sensitive adhesive sheet.

Images