JP7052726B2 - Adhesive sheet and its manufacturing method - 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. And its manufacturing method.

In order to improve the visibility of image display devices such as personal computers, mobile terminals (PDAs) and touch panels, image display panels such as liquid crystal displays (LCDs), plasma displays (PDPs) and electroluminescence displays (ELDs) and their components. A method of using an adhesive sheet is known when filling a gap between a protective panel and a touch panel member arranged on the front side (visual side) with an adhesive.

Regarding this type of pressure-sensitive adhesive sheet, for example, in Patent Document 1 (Japanese Unexamined Patent Publication No. 2014-094976), an image of irradiating light having a wavelength of 360 nm or less from the side surface side of the laminated body in which the pressure-sensitive adhesive layer and the base material layer are laminated. An adhesive sheet for a display device and a method for manufacturing the same are disclosed.

In Patent Document 2 (Japanese Patent No. 4971529), an adhesive sheet primaryly crosslinked by ultraviolet rays is attached to an image display device constituent member, and then the adhesive sheet is irradiated with ultraviolet rays via the image display device constituent member to be secondarily cured. The method is disclosed.

The image display device constituent member as described above often has an uneven portion on the adherend surface, such as a printed portion formed on the adherend surface, and in order to improve visibility, such an image display device component often has such an uneven portion. It is preferable that the uneven portion is also filled with the adhesive. Therefore, in a normal state, that is, in a room temperature state, it can have a degree of adhesiveness (referred to as "tackiness") that can be peeled off, and when heated to a temperature at which hot meltability is possible, it becomes fluid. Adhesive compositions and adhesive sheets have been developed that can follow the unevenness of the bonded surface and fill every corner, and finally can firmly adhere the adherends to each other.

For example, Patent Document 3 (Japanese Unexamined Patent Publication No. 2015-105296) describes 100 parts by mass of the acrylic copolymer (A), 0.5 to 20 parts by mass of the cross-linking agent (b), and a photopolymerization initiator (C). A pressure-sensitive adhesive resin composition containing 0.1 to 5 parts by mass, wherein the acrylic copolymer (A) is a graft having a weight average molecular weight of ^5.0 × 10 ⁴ to 5.0 × 105. 6. It is a copolymer, contains a repeating unit derived from (meth) acrylic acid ester as a stem component of the graft copolymer, and has a number average molecular weight of 5.0 × 10 ² or more as a branch component of the graft copolymer. It is characterized by containing a repeating unit derived from a macromonomer of less than 0 × 10 ³ and containing the repeating unit derived from the macromonomer in a ratio of 0.1 to 3 mol% in the acrylic copolymer (A). The pressure-sensitive adhesive resin composition described above is disclosed.

This type of adhesive sheet is formed as an adhesive sheet laminate by laminating a peelable protective film (also referred to as "release film") on the adhesive surface from the viewpoint of ensuring handleability and preventing foreign matter from adhering to the adhesive surface. It is common to distribute it. In particular, regarding the transparent double-sided adhesive sheet used for bonding image display device components such as touch panel touch panels, liquid crystal panels, and surface protection panels, the transparent adhesive sheet itself is used from the viewpoint of ensuring optical characteristics and flexibility. Since it is preferable to make it thin and flexible, many have been used as an adhesive sheet laminate formed by laminating a release film on an adhesive sheet.

Regarding this type of pressure-sensitive adhesive sheet laminate, for example, in Patent Document 4 (Japanese Unexamined Patent Publication No. 2009-102467), an ABA-type triblock copolymer composed of an acrylic acid ester and a methacrylic acid ester and a resin having a hydroxyl group are polymerized. A pressure-sensitive adhesive sheet obtained by sandwiching a blended acrylic transparent pressure-sensitive adhesive composition between mold-removing sheets and hot-melt molding is disclosed.

Patent Document 5 (Japanese Unexamined Patent Publication No. 2010-185037) is a pressure-sensitive adhesive sheet having an pressure-sensitive adhesive layer on at least one surface of a release film and cross-linking the pressure-sensitive adhesive layer. Disclosed is an adhesive sheet characterized by being in the range of 50,000 Pa or more and 1 million Pa or less in any of the temperature ranges of 25 ° C to 120 ° C when the temperature dispersion behavior of the tensile storage elastic modulus at a frequency of 1 Hz is measured. ing.

Japanese Unexamined Patent Publication No. 2014-094976 Japanese Patent No. 4971529 Japanese Unexamined Patent Publication No. 2015-105296 Japanese Unexamined Patent Publication No. 2009-102467 Japanese Unexamined Patent Publication No. 2010-185037

Since the adhesive sheet having a photocurable property (referred to as "photocurable") has a low gel content before photocuring, the release film is laminated on both the front and back sides of the adhesive sheet at room temperature. When stored in a state, there was a problem that the adhesive squeezed out from the laminated end face and dust adhered. Above all, when a long adhesive sheet is rolled into a roll and stored in the state of the adhesive sheet rolled body, the adhesive is stored in a state where the pressure is applied to the adhesive sheet, so that the adhesive especially bites from the end face of the roll. It had the problem of being easy to put out. If the adhesive squeezes out from the end face of the roll, the squeezed out adhesive fuses at the end face, making it difficult to feed the adhesive sheet from the roll, or contaminating the device when cutting the adhesive sheet. It will cause problems. Therefore, extra costs such as storing the adhesive sheet winding body in a low temperature state have been required.

The present invention relates to a photocurable pressure-sensitive adhesive sheet, and a new pressure-sensitive adhesive sheet capable of effectively suppressing the pressure-sensitive adhesive from squeezing out from the end face even when stored at room temperature, and a new pressure-sensitive adhesive sheet thereof. It is intended to propose a method.

The present invention is a photocurable pressure-sensitive adhesive sheet, in which a region having a width w [mm] from the edge of the sheet toward the center of the sheet (referred to as "edge width region") and the sheet from the edge width region. The central region (referred to as "central region") is characterized in that the following conditions (1) and (2) are satisfied, and the standard deviation of the gel fraction in the edge width region is 3% or less. We propose an adhesive sheet.
(1) The gel fraction of the pressure-sensitive adhesive sheet in the edge width region is larger than the gel fraction of the pressure-sensitive adhesive sheet in the central region.
(2) When the thickness of the adhesive sheet is d [mm], 30d <w <100d is satisfied.

The present invention is an adhesive sheet winding body with a release film, in which an adhesive sheet with a release film formed by laminating a release film on one side or both sides of the adhesive sheet is wound in a roll shape.
The adhesive sheet has photocurability and has a width w [mm] from the edge of both sides of the sheet in the lateral direction toward the center of the sheet (referred to as "edge width region") and the edge width. The area in the center of the sheet (referred to as the "central area") rather than the area satisfies the following conditions (1) and (2).
Further, we propose an adhesive sheet wound body with a release film, characterized in that the standard deviation of the gel fraction in the edge width region is 3% or less .
(1) The gel fraction of the pressure-sensitive adhesive sheet in the edge width region is larger than the gel fraction of the pressure-sensitive adhesive sheet in the central region.
(2) When the thickness of the adhesive sheet is d [mm], 30d <w <100d is satisfied.

The present invention also prepares a pressure-sensitive adhesive sheet with a release film, which is formed by laminating a release film on one side or both sides of a photocurable pressure-sensitive adhesive sheet as a method for producing the above-mentioned pressure-sensitive adhesive sheet. By irradiating the edge width region of the adhesive sheet with light, the gel fraction of the adhesive sheet in the edge width region is made larger than the gel fraction of the adhesive sheet in the central region. Propose a manufacturing method.

According to the pressure-sensitive adhesive sheet, the pressure-sensitive adhesive sheet winder with a release film, and the manufacturing method thereof proposed by the present invention, the pressure-sensitive adhesive is effectively suppressed from squeezing out from the end face even when stored at room temperature. can do. For example, even when the adhesive sheet is stored or transported in a rolled state, it is possible to effectively prevent the adhesive from squeezing out from the end face of the roll.

It is a perspective view which showed an example of the manufacturing method which concerns on an example of embodiment of this invention. It is a top view which showed an example of the manufacturing method which concerns on an example of embodiment of this invention. It is a schematic diagram which showed the example of the method of irradiating both ends of the adhesive sheet with a release film in the sheet width direction (TD direction), and (A) is the method of irradiating light from the direction perpendicular to the sheet surface. (B) is a figure explaining a method of irradiating light from an extension direction of a sheet surface.

Next, the present invention will be described based on examples of embodiments. However, the present invention is not limited to the embodiments described below.

[Book adhesive sheet]
The pressure-sensitive adhesive sheet (referred to as “the present pressure-sensitive adhesive sheet”) according to an example of the embodiment of the present invention is a photocurable pressure-sensitive adhesive sheet, and has a width w [mm] from the edge of the sheet toward the center of the sheet. In other words, the gel fraction of the adhesive sheet in the region of the width w [mm] along the sheet edge width (referred to as "edge width region") on the sheet surface is the region in the center of the sheet ("" It is a pressure-sensitive adhesive sheet having a feature of being larger than the gel fraction of the pressure-sensitive adhesive sheet in the "central region").

<Form of this adhesive sheet>
The present adhesive sheet may be a rectangular adhesive sheet, a long adhesive sheet, an adhesive sheet wound body wound in a roll shape, or another form. ..
Further, the present adhesive sheet may exist in a state where the release films are laminated on one side or both sides of the front and back surfaces.
At this time, "long" means that the length dimension is larger than the width dimension. Specifically, it means that the length dimension is 5 m or more, preferably 10 mm or more. The upper limit is not limited. If specified, the upper limit is preferably 500 m or less.

Among them, as a preferable example of the present adhesive sheet, the adhesive sheet with a release film, which is formed by laminating a release film on one side or both sides of the present adhesive sheet, is wound into a roll shape. A rotating body (also referred to as a "main winding body") can be mentioned.
Further, in a normal pressure-sensitive adhesive sheet wound body, the wider the roll width, the more remarkable the pressure-sensitive adhesive squeezes out. On the other hand, in the case of the main wound body, it is possible to effectively suppress the squeeze out of the adhesive even with a wide roll. Therefore, the roll width of the wound body is preferably 20 mm to 2000 mm, more preferably 50 mm or more or 1500 mm or less.

<Gel fraction of this adhesive sheet>
According to the studies by the present inventors, it has been found that the phenomenon of the adhesive squeezing out from the end face of the roll differs depending on the thickness of the adhesive sheet sandwiched between the release films. That is, in the present adhesive sheet, if the width w [mm] of the edge width region, that is, the portion having a high gel fraction is small with respect to the thickness d of the adhesive sheet, even if the gel fraction in the edge width region is increased. For example, when the adhesive sheet is stored as a rolled adhesive sheet wound body, it has been confirmed that the adhesive gradually squeezes out from the end face of the roll due to the winding pressure.
It was also found that the behavior of the adhesive squeezing out has a certain relationship between the width of the edge width region and the thickness of the adhesive sheet. That is, if the width w [mm] of the portion having a high gel fraction is set at a ratio of 30d <w to the thickness d [mm] of the adhesive sheet, the adhesive sheet can be rolled as well as a normal adhesive sheet. Even when stored as a rotating body, it is possible to effectively suppress the adhesive from squeezing out from the end face of the roll by appropriately increasing the gel fraction in the edge width region.
From this point of view, the relationship between the width w [mm] of the edge width region, that is, the portion having a high gel fraction, and the thickness d [mm] of the adhesive sheet is preferably 30d <w, particularly 35d <w, Among them, 40d <w, and among them, 45d <w is more preferable.

On the other hand, when this adhesive sheet is used as an adhesive sheet, the edge width region is usually cut off and used. Therefore, if the width of the edge width region is too large, many parts are not used as the adhesive sheet. The cost will be high.
From this point of view, w <100d is preferable, w <80d among them, w <70d among them, and w <60d among them is more preferable.

Summing up the above, the width w is preferably any one of 30d <w <100d, 30d <w <80d, 30d <w <70d or 30d <w <60d, and 35d <w <100d, 35d <. It is more preferable that either w <80d, 35d <w <70d or 35d <w <60d, and 40d <w <100d, 40d <w <80d, 40d <w <70d or 40d <w <60d. It is more preferably either 45d <w <100d, 45d <w <80d, 45d <w <70d or 45d <w <60d.

For example, when the thickness d of the present adhesive sheet is 0.1 mm, the width w [mm] of the edge width region, which is a portion having a high gel fraction, is preferably 3 mm to 10 mm, and more than 3.5 mm or more. It is more preferably 8.0 mm or less, particularly 4.0 mm or more or 7.0 mm or less, and particularly preferably 4.5 mm or more or 6.0 mm or less.

When the present adhesive sheet is a long adhesive sheet, the region having a width w [mm] from the edge of both sides of the sheet in the lateral direction toward the center of the sheet may be the edge width region.

The gel fraction of the pressure-sensitive adhesive sheet in the edge width region is preferably 1% or more larger than the gel fraction of the pressure-sensitive adhesive sheet in the central region, particularly 5% or more, 10% or more among them, and 15% or more or 99 among them. It is preferably larger by% or less.

Specifically, the gel fraction in the edge width region is preferably 15% or more and less than 100%, particularly 20% or more, 25% or more among them, and 30% or more or 99% or less among them. Is even more preferable.
Taken together, the gel fraction in the edge width region is preferably 15% or more and less than 100% or 15% or more and 99% or less, and 20% or more and less than 100% or 20% or more and 99% or less. Is more preferably 25% or more and less than 100%, or more preferably 25% or more and 99% or less, and most preferably 30% or more and less than 100%, or 30% or more and 99% or less.

Further, in the edge width region, the standard deviation of the gel fraction is preferably 3% or less, particularly 2.5% or less, and more preferably 2% or less.
Even in the central region, the standard deviation of the gel fraction is preferably 3% or less, particularly 2.5% or less, and more preferably 2% or less.
As described above, the standard deviation of the gel fraction in the edge width region is 3% or less, which means that the gel fraction in the edge width region is uniform, and thus the edge. Since the gel fraction in the width region is uniformly high, it is possible to more reliably prevent the adhesive from squeezing out from the end face.
As described above, the smaller the standard deviation of the gel fraction in the edge width region, the better the uniformity. Therefore, the lower limit thereof is preferably 0% or more or 1% or more, for example. However, the lower limit is not particularly limited.

As a preferable form of the present adhesive sheet, particularly the main wound body, a photocurable having an edge width region having a gel fraction of 15 to 100% and a central region having a gel fraction smaller than the edge width region. An adhesive sheet having a property, wherein the width w [mm] of the edge width region and the thickness d [mm] of the adhesive sheet satisfy 30d <w <100d. can. Details are as described above.

As a more preferable form of the wound body, it has a photocurable property having an edge width region having a gel fraction of 15 to 100% and a central region having a gel fraction of 0% or more and less than 15%. Examples of the pressure-sensitive adhesive sheet include a pressure-sensitive adhesive sheet in which the width w [mm] of the edge width region and the thickness d [mm] of the pressure-sensitive adhesive sheet satisfy 30d <w <100d. Details are as described above.

The gel fraction can be obtained as follows.
Approximately 0.05 g of adhesive is collected from the edge width region and the central region, wrapped in a bag shape with a stainless mesh (# 200) whose mass (X) has been measured in advance, and the mouth of the bag is folded and closed. After measuring the mass (Y) of, it is immersed in 100 ml of ethyl acetate and stored at 23 ° C. for 24 hours in the dark. Next, the package was taken out and heated at 70 ° C. for 4.5 hours to evaporate the attached ethyl acetate, the mass (Z) of the dried package was measured, and the obtained mass was substituted into the following formula. You can ask.
Gel fraction [%] = [(ZX) / (YX)] x 100

This adhesive sheet has photocurability. In particular, the gel fraction at the time of final curing, for example, the gel fraction of the adhesive sheet after the present adhesive sheet is interposed between the adherends and irradiated with light to be photo-cured (“Gel fraction at the time of final curing”). (Referred to as) is 20% to 100%, more preferably 25% or more or 95% or less, and more preferably 30% or more or 90% or less. Here, the "gel fraction at the time of final curing" also means the gel fraction when the present adhesive sheet is completely cured, and the gel fraction when used without being completely cured. It also means rate.

Whether or not the adhesive sheet used corresponds to this adhesive sheet is determined by collecting a measurement sample at a constant width from the edge width region toward the center of the sheet, preferably every 0.1 mm to 1.0 mm width. , The gel fraction of each measurement sample is measured, and (1) whether the gel fraction of the adhesive sheet in the edge width region is larger than the gel fraction of the adhesive sheet in the central region, and (2) the central region. It may be investigated whether or not the width d [mm] of the edge width region having a larger gel fraction satisfies 30d <w <100d.
At this time, the gel fraction in the central region is preferably 0% or more and less than 15% as described above, and the gel fraction in the edge width region is preferably 15% or more and less than 100%.

Further, in the present invention, when the gel fraction from the edge of the pressure-sensitive adhesive sheet to the central region continuously changes and the boundary between the two is unclear, the gel fraction of 15% is used as the boundary. That is, a region having a gel fraction of 15% or more is defined as an edge width region. When the gel fraction from the edge of the adhesive sheet to the central region is continuously changed in this way, the values of the gel fraction in the edge width region and the central region are the average value of each region. do.

The thickness d of the pressure-sensitive adhesive sheet is preferably 0.05 mm to 1 mm. Within this range, if it is a thin adhesive sheet having a thickness of, for example, 0.05 mm, it is possible to provide an adhesive sheet having excellent print step followability. Further, in a thick adhesive material layer having a thickness of 1 mm or the like, the amount corresponding to the printing step is formed in advance, so that it is possible to suppress the overflow of the adhesive material at the time of bonding.
Therefore, the thickness d of the pressure-sensitive adhesive sheet is preferably 0.05 mm to 1 mm, more preferably 0.075 mm or more or 0.8 mm or less, and more preferably 0.1 mm or more or 0.5 mm or less.

Overall, the thickness d of the adhesive sheet is preferably any one of 0.05 mm to 1 mm, 0.05 mm to 0.8 mm, or 0.05 mm to 0.5 mm or less, and 0.075 mm to 1 mm. , 0.075 mm to 0.8 mm or 0.075 mm to 0.5 mm or less, more preferably 0.1 mm to 1 mm, 0.1 mm to 0.8 mm or 0.1 mm to 0.5 mm or less. It is most preferable to be either.
The thickness d of the adhesive sheet does not include the thickness of the release film.

<Structure of this adhesive sheet>
The present pressure-sensitive adhesive sheet may be a single layer of a pressure-sensitive adhesive layer made of a pressure-sensitive adhesive composition, or may be provided with a plurality of layers of pressure-sensitive adhesive layers such as two layers and three layers.
Further, the present adhesive sheet may have a base material layer (a layer having no adhesiveness) as a core layer, and a layer made of an adhesive material may be laminated on both sides of the base material layer. .. In the case of such a configuration, it is preferable that the base material layer as the core layer has a material and characteristics such that the pressure-sensitive adhesive sheet laminate can be heat-molded.

Further, the softer the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition, the more remarkable the pressure-sensitive adhesive squeezes out. The effect of the present invention is particularly remarkable.
Specifically, when the value of the loss tangent (Tan δ = loss shear elastic modulus G'' / storage shear elastic modulus G') of the present adhesive sheet exceeds 1 at a frequency of 1 Hz and a temperature of 80 ° C., the present invention The effect is particularly noticeable. That is, under the above conditions, the fact that Tan δ of the pressure-sensitive adhesive sheet exceeds 1, means that the contribution of viscosity is larger than that of elasticity, and the pressure-sensitive adhesive tends to flow more easily. Therefore, if the technique of the present invention is used for a pressure-sensitive adhesive sheet having a Tan δ of more than 1, the effect of preventing the pressure-sensitive adhesive from squeezing out becomes particularly remarkable.
From the above, it is preferable that Tan δ of this adhesive sheet exceeds 1. The upper limit does not necessarily have to be set. If the upper limit is intentionally set, it is 10 or less.

In this pressure-sensitive adhesive sheet, in order to adjust the value of Tan δ, it may be adjusted according to the constituent components of the pressure-sensitive adhesive composition. For example, it can be adjusted by the type and composition ratio of the monomers constituting the base resin, the types and amounts of the cross-linking agent and the initiator, the molecular weight of the base resin, the cross-linking conditions, and the like.

The value of Tan δ is determined by using a viscoelasticity measuring device dynamic analyzer (for example, “RDAII” manufactured by Leometrics) to determine the storage shear modulus (G') and loss shear modulus (G ″) under the following conditions. It may be obtained by measuring.
<Conditions>
・ Jig: Φ20mm parallel plate ・ Temperature: -50 to 200 ℃ (measured at a heating rate of 3 ℃ / min)
・ Frequency: 1Hz
・ Distortion angle: 0.1%

<Material composition of the adhesive layer constituting this adhesive sheet>
The pressure-sensitive adhesive layer of the present pressure-sensitive adhesive sheet can be formed from a conventionally known pressure-sensitive adhesive material as long as it has photocurability.
Here, as the photocurability, it is preferable that the photocurability is curable with light having a wavelength other than the electron beam, specifically, a wavelength region of 200 nm to 780 nm.

The pressure-sensitive adhesive layer of this pressure-sensitive adhesive sheet is based on, for example, 1) (meth) acrylic acid ester-based polymer (meaning that it contains a copolymer, hereinafter referred to as “acrylic acid ester-based (co) polymer”) as a base resin. A pressure-sensitive adhesive composition obtained by blending a cross-linking monomer, a cross-linking initiator, a reaction catalyst, etc. as necessary.
2) A pressure-sensitive adhesive composition using a butadiene or isoprene-based (co) polymer as a base resin, to which a cross-linking monomer and, if necessary, a cross-linking initiator and a reaction catalyst are blended.
3) A pressure-sensitive adhesive composition obtained by using a silicone-based polymer as a base resin and blending it with a cross-linking monomer, a cross-linking initiator, a reaction catalyst, etc., if necessary.
4) Examples thereof include a polyurethane-based pressure-sensitive adhesive composition using a polyurethane-based polymer as a base resin.

Among them, as an example of a suitable pressure-sensitive adhesive composition constituting the pressure-sensitive adhesive layer, a (meth) acrylic (co) polymer (a) as a base resin, a cross-linking agent (b), and a photopolymerization initiator ( A resin composition containing c) and can be mentioned.

((Meta) acrylic (co) polymer (a))
The (meth) acrylic (co) polymer (a) has characteristics such as glass transition temperature (Tg) depending on the type, composition ratio, polymerization conditions, etc. of the acrylic monomer and methacrylic monomer used for polymerizing the polymer. Can be adjusted as appropriate.
Among the acrylic acid ester (co) polymers, the (meth) acrylic acid alkyl ester-based (co) polymer is particularly preferable.
The polymerization form of the acrylic acid ester copolymer may be any of a random copolymer, a block copolymer, and a graft copolymer.

Examples of the monomer component constituting the (meth) acrylic acid alkyl ester (co) polymer 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 (meth) ) 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, Examples thereof include dicyclopentenyloxyethyl (meth) acrylate and benzyl (meth) acrylate.

Further, as the monomer component constituting the (meth) acrylic acid alkyl ester (co) polymer, in addition to those mentioned above, hydroxyethyl (meth) acrylate having a hydrophilic group, an organic functional group, etc., hydroxypropyl ( Hydroxyl-containing (meth) acrylates such as meth) acrylates, hydroxybutyl (meth) acrylates and glycerol (meth) acrylates, (meth) acrylic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, 2- (meth) Acryloyloxypropylhexahydrophthalic acid, 2- (meth) acryloyloxyethylphthalic acid, 2- (meth) acryloyloxypropylphthalic acid, 2- (meth) acryloyloxyethyl maleic acid, 2- (meth) acryloyloxypropylmaleine Acids, 2- (meth) acryloyloxyethyl 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, Acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride, epoxy group-containing monomers such as (meth) glycidyl acrylate, α-glycidyl acrylate, and 3,4-epoxybutyl (meth) acrylate, dimethylamino Amino group-containing (meth) acrylic acid ester-based monomers such as ethyl (meth) acrylate and diethylaminoethyl (meth) acrylate, (meth) acrylamide, Nt-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N. -Amide-containing monomers such as methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, diacetone acrylamide, maleic acid amide, and maleimide, and heterocyclic basics such as vinylpyrrolidone, vinylpyridine, and vinylcarbazole. A monomer or the like can also be used.
Furthermore, styrene, t-butyl styrene, α-methyl styrene, vinyl toluene, acrylonitrile, methacrylonitonyl, vinyl acetate, vinyl propionate, alkyl vinyl ether, hydroxyalkyl vinyl ether, which can be copolymerized with the acrylic monomer or methacrylic monomer, Various vinyl monomers such as alkyl vinyl monomers can also be appropriately used.

Among them, as an example of a preferable base polymer, a (meth) acrylic copolymer (a1) made of a graft copolymer having a macromonomer as a branch component can be mentioned.

If the pressure-sensitive adhesive layer is formed using the acrylic copolymer (a1) as a base resin, the pressure-sensitive adhesive layer can exhibit self-adhesiveness while maintaining a sheet shape at room temperature, and when heated in an uncrosslinked state, it can exhibit self-adhesiveness. It has a hot-melt property that melts or flows, and can be photo-cured, and after photo-curing, it can exhibit excellent cohesive force and adhere.
Therefore, if an acrylic copolymer (a1) is used as the base polymer, 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 component constituting the stem component of the acrylic copolymer (a1) is the flexibility of the pressure-sensitive adhesive layer at room temperature and the wettability of the pressure-sensitive adhesive layer to the adherend, that is, Since it affects the adhesiveness, the glass transition temperature is preferably −70 ° C. to 0 ° C., particularly −65 ° C., in order for the present adhesive sheet to obtain appropriate adhesiveness (tackiness) at room temperature. Above or below −5 ° C., particularly preferably −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 (a1) include various monomer components listed above.

It is preferable that the acrylic copolymer (a1) has a macromonomer introduced 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 (a1).
Specifically, since the glass transition temperature (Tg) of the macromonomer affects the heating and melting temperature (hot melt temperature) of the present 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 by 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 a pressure-sensitive adhesive composition, and the physical cross-linking is dissolved by heating to an appropriate temperature. It is also preferable to adjust the molecular weight and content of the macromonomer so that the fluidity can be obtained.
From this point of view, the macromonomer is preferably contained in the acrylic copolymer (a1) in a proportion of 5% by mass to 30% by mass, particularly 6% by mass or more or 25% by mass or less, and 8% by mass among them. It is preferably more than or less than 20% by mass.
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 manufactured 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 (b))
As the cross-linking agent (b), a cross-linking monomer used for cross-linking the acrylic acid 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. Organic metal compounds having a metal complex such as a base resin, zinc, aluminum, sodium, zirconium and calcium can be preferably used.

The content of the cross-linking agent (b) 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 sheet. It is preferably contained in 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 (c))
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 the photopolymerization initiator (c).
The photopolymerization initiator (c) is roughly classified into two types according to the radical generation mechanism, that is, a cleavage type photopolymerization initiator capable of cleaving and decomposing a single bond of the photopolymerization initiator itself to generate a radical, and a photoexcitation. The 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 light is crosslinked by light irradiation as compared with the case where the hydrogen extraction type is used. It 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 reaction decomposition product, so that absorption in the visible light region is eliminated and a decolorizing agent can be appropriately selected.
On the other hand, the hydrogen abstraction type photopolymerization initiator does not generate a decomposition product like a cleaved type photopolymerization initiator during a 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 is subject to damage. Damage to the body can be reduced.

The content of the photopolymerization initiator (c) 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, particularly with respect to 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 (c) can be used alone or in combination of two or more.

(Other ingredients)
As a component other than the above, the pressure-sensitive adhesive sheet may contain a known component contained in a normal pressure-sensitive adhesive composition. For example, tackifier resins, antioxidants, light stabilizers, metal deactivators, rust inhibitors, anti-aging agents, hygroscopic agents, antioxidants, sensitizers, antistatic agents, defoamers, inorganics. It is possible to appropriately contain various additives such as particles.
Further, if necessary, a reaction catalyst (tertiary amine compound, quaternary ammonium compound, tin laurate compound, etc.) may be appropriately contained.

[Manufacturing method of this adhesive sheet]
For this adhesive sheet, a release film-attached pressure-sensitive adhesive sheet is prepared by laminating a release film on one side or both sides of a photocurable pressure-sensitive adhesive sheet, and the edge width region of the release film-attached pressure-sensitive adhesive sheet is formed. It can be manufactured by increasing the gel content of the pressure-sensitive adhesive sheet in the edge width region by irradiating with light.
At this time, the gel fraction of the pressure-sensitive adhesive sheet is preferably 0 to 10%, and more preferably 0 to 5%, particularly 0 to 3%, to further enjoy the effect of the present invention. can.

<Manufacturing method of adhesive sheet winding body>
Next, as an example of the present pressure-sensitive adhesive sheet, a method for manufacturing a pressure-sensitive adhesive sheet wound body, that is, a roll-shaped pressure-sensitive adhesive sheet, which is formed by winding a long pressure-sensitive adhesive sheet into a roll shape, will be described in detail.

As a method for manufacturing the roll-shaped adhesive sheet 2, for example, an adhesive with a release film formed by laminating long release films 11 and 12 on one side or both sides of a long adhesive sheet 10 having photocurability. In the step of transporting the sheet 1 in a certain direction (MD direction), as shown in FIGS. 1 and 2, the sheet from the edge of the sheet at both ends of the adhesive sheet 1 with a release film in the sheet width direction (TD direction). The edge width regions 1A and 1A having a width w [mm] toward the center are irradiated with light, respectively, to cure the edge width regions 1A and 1A of the adhesive sheet 10, and then the release film is attached. A manufacturing method characterized by winding the pressure-sensitive adhesive sheet 1 into a roll shape to obtain a roll-shaped pressure-sensitive adhesive sheet 2 can be mentioned.

(Adhesive sheet with release film 1 before light irradiation)
The adhesive sheet 1 with a release film before light irradiation is a long laminated sheet in which the release films 11 and 12 are laminated on both the front and back sides of the adhesive sheet 10, and the adhesive sheet 10 has photocurability. Moreover, the gel content is preferably in the range of 0 to 15% in any part of the pressure-sensitive adhesive sheet 10, and more preferably 12% or less, and more preferably 10% or less. However, the release film may be laminated only on one side of the front and back of the adhesive sheet 10.

As a method for producing the pressure-sensitive adhesive sheet 1 with a release film, for example, a method in which a pressure-sensitive adhesive composition is sandwiched between two release films 11 and 12 and a laminator is used to form a pressure-sensitive adhesive layer can be mentioned. Further, as another method, a method of applying the pressure-sensitive adhesive composition to one release film 11 to form a pressure-sensitive adhesive layer and then laminating the other release film 12 can be mentioned. However, the present invention 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.

As the release films 11 and 12, known release films can be appropriately used. For example, a polyester-based, polypropylene-based, or polyethylene-based cast film or stretched film coated with a silicone resin and subjected to a mold release treatment, or a release paper or the like can be appropriately selected and used.
Further, the release films 11 and 12 can also be similarly blended with components that can be blended in the pressure-sensitive adhesive composition described above.
As a method of curing the edge width region, as described later, when the method of irradiating light through the release film is performed, the release film preferably has a property of not absorbing or reflecting the irradiation light. ..

When the release films 11 and 12 are laminated on both sides of the pressure-sensitive adhesive sheet 10, even if one release film 11 has the same laminated structure or material as the other release film 12, it has a different laminated structure or material. It may be the one.
Further, the thickness may be the same or different. Further, a release film having a different peeling force and a release film having a different thickness can be laminated on both sides of the pressure-sensitive adhesive sheet 10.

The thickness of the release films 11 and 12 is preferably 50 to 200 μm, more preferably 75 μm or more or 150 μm or less. With the thickness in this range, the light irradiation from above the sheet is not hindered, and the gel fraction in the edge width region and the central region can be easily adjusted.

(Photo-curing method for edge width region 1A)
As a method of irradiating the edge width region 1A with light to cure it, as shown in FIG. 1, from above the upper surface of the adhesive sheet 1 with a release film, or from below with respect to the lower surface of the sheet. Or, it is preferable to irradiate both the upper and lower surfaces of the sheet with light from both the upper and lower sides.
Above all, when the upper surface of the adhesive sheet 1 with a release film is irradiated with light from above, the edge width regions 1A and 1A on both sides of the adhesive sheet 1 with a release film in the lateral direction (TD direction) It is preferable to install the light source 3 above and irradiate the light from vertically upward or diagonally 60 to 90 ° above the upper surface of the sheet, particularly 70 to 90 ° above, and 80 to 90 ° above. By irradiating at such an angle, the difference (boundary) in the gel fraction between the edge width region and the central region becomes clear, so that the adhesive can be more efficiently suppressed from squeezing out. ..
When irradiating the lower surface of the adhesive sheet 1 with a release film with light from below, the edge widths on both sides of the adhesive sheet 1 with a release film in the lateral direction (TD direction) for the same reason as described above. It is recommended to install a light source below the areas 1A and 1A and irradiate the light vertically downward with respect to the lower surface of the sheet, or diagonally 60 to 90 ° below, particularly 70 to 90 ° below, and 80 to 90 ° below. preferable.

Here, as a method of irradiating both ends of the adhesive sheet 1 with a release film in the sheet width direction (TD direction) while transporting the adhesive sheet 1 with a release film in a certain direction (MD direction), for example, FIG. As shown in 3 (A), light is irradiated from the direction perpendicular to the sheet surface of the adhesive sheet 1 with a release film. Specifically, the light source 3 is installed above the upper surface or below the lower surface, and the light source 3 is installed from above with respect to the upper surface of the adhesive sheet 1 with a release film, from below with respect to the lower surface thereof, or with respect to both sides thereof. A method of irradiating light from both the top and bottom can be mentioned.
Further, as shown in FIG. 3B, the light source 3 is installed in the sheet surface extension direction (horizontal horizontal side in the figure) of the adhesive sheet 1 with a release film, and the sheet width direction of the adhesive sheet 1 with a release film. (TD direction) A method of irradiating both end faces with light from the side in the horizontal direction can be mentioned.
Comparing these methods, light is emitted from the extension direction of the sheet surface with respect to both end faces in the sheet width direction (TD direction) of the adhesive sheet 1 with a release film, that is, from the horizontal side as shown in FIG. 3 (B). It was found that the irradiating method can cure only the surface portions of both end faces in the width direction of the sheet, so that the adhesive gradually squeezes out due to the winding pressure applied in the roll state. On the other hand, according to the method of irradiating the pressure-sensitive adhesive sheet 1 with a release film with light from both the upward, downward, and vertical directions, the width of the light irradiation is adjusted by the winding pressure applied in the roll state. It has been confirmed that the adhesive can be effectively prevented from squeezing out gradually.
As a means for manufacturing the adhesive sheet wound body with the release type film, the method of irradiating light from the lateral side in the horizontal direction as shown in FIG. 3B is not excluded. However, as compared with this method, the method of irradiating light from the vertical direction as shown in FIG. 3A can be manufactured extremely efficiently.

Further, as described above, according to the method of irradiating light from both the upward, downward, and vertical directions, the standard deviation of the gel fraction in the edge width region can be set to 3% or less as described above. As described above, according to such a method, the curing in the edge width region can be made uniform, and the adhesive can be effectively prevented from gradually squeezing out.

In order to adjust the gel fraction of the edge width region 1A of the pressure-sensitive adhesive sheet 10 within a predetermined range, for example, it is adjusted by the integrated light beam amount per unit time, the type and content of the cross-linking agent and the cross-linking initiator in the pressure-sensitive adhesive sheet, and the like. can do. However, it is not limited to these.

As the light source 3 for irradiating light, it is preferable to use an LED from the viewpoint of high light directivity. Although each manufacturer discloses a light source 3 having various emission wavelengths, it is particularly preferable to emit light in a wavelength range absorbed by a generally used initiator. Specifically, it is preferably 200 nm to 450 nm, particularly preferably 220 nm or more or 400 nm or less.
Further, as the light source 3 for irradiating light, it is preferable to use a light source having a light diffusion angle of 50 ° or less, particularly 40 ° or less, and particularly 30 ° or less, from the viewpoint of high light directivity. By using a light source with such a light diffusion angle, the difference (boundary) in the gel fraction between the edge width region and the central region becomes clear, so that the adhesive squeeze out is suppressed more efficiently. be able to.

When irradiating the light, it is preferable to irradiate the light having a wavelength of at least 200 nm to 450 nm from the viewpoint of the absorption wavelength of the initiator.
Further, from the viewpoint of obtaining a gel fraction sufficient to suppress the squeeze out of the adhesive when irradiated with light, 1000 mJ / cm ² to 10000 mJ / cm ² per unit area, especially 1500 mJ / cm ² or more or more. It is preferable to irradiate each side of the edge width region with light having an integrated light amount of 9000 mJ / cm ² or less, particularly 2000 mJ / cm ² or more or 8000 mJ / cm ² or less.
The integrated light beam amount per unit time can be adjusted by the output of the light source, the distance between the light source and the adhesive sheet with the release film, the transport speed of the adhesive sheet with the release film, and the like. As an example, preferable conditions are listed below.

Further, the output of the light source 3 is preferably 0.5 W / cm ² to 50 W / cm ² from the viewpoint of contributing to the compactification of the equipment, and above all, 1.0 W / cm ² or more or 40 W / cm ² or less. Among them, it is more preferably 2.0 W / cm ² or more or 30 W / cm ² or less.

Further, the length of the light source 3 in the MD direction, that is, the length in the MD direction of irradiating light, is preferably 30 mm to 2000 mm, particularly 50 mm or more or 1000 mm or less, from the viewpoint of compactification of manufacturing equipment. Above all, it is more preferably 100 mm or more or 500 mm or less.

The transport speed when transporting the adhesive sheet 1 with a release film in a certain direction (MD) is preferably 1 m / min to 30 m / min from the viewpoint of imparting productivity and a sufficient increase in gel fraction. Above all, it is more preferably 3 m / min or more or 25 m / min or less, and more preferably 5 m / min or more or 20 m / min or less.

For example, as the light source 3, an LED having an output of 7 W / cm ² , an irradiation wavelength of 365 nm, a light diffusion angle of 30 °, and an MD length (light source length in the table) of 44 mm is used, and the distance between the light source 3 and the roll-shaped adhesive sheet 2 ( When the light source distance in the table) is set to 10 mm and UV irradiation is performed for about 3.8 s, the integrated light amount becomes about 3200 mJ.

(Take-up)
When the pressure-sensitive adhesive sheet 1 with a release film obtained by photo-curing the edge width regions 1A and 1A is wound into a roll, the winding tension per 1 m of the film width, that is, the winding tension is preferably 20 to 200 N / m. ..
When the winding tension is 20 to 200 N / m width, winding shift, winding swelling, and winding wrinkles do not occur, and an increase in phase difference due to film orientation due to tension can be reduced, which is preferable.
From this point of view, the winding tension is preferably 30 to 150 N / m width, and more preferably 50 N / m width or more or 100 N / m width or less.

The materials, the laminated structure, and the method for producing the pressure-sensitive adhesive sheet with a release film before light irradiation may be the same as those of the pressure-sensitive adhesive sheet 1 with a release film.
Further, the photocuring method of the edge width region may be the same as that of the pressure-sensitive adhesive sheet 1 with a release film.

The photo-curing method does not necessarily have to be performed in the state of the pressure-sensitive adhesive sheet 1 with a release film as described above. For example, the edge width region of the pressure-sensitive adhesive sheet may be cured before the release film is attached, and then the release film may be attached. By adopting such a method, even when a release film containing a substance that suppresses light transmission such as an ultraviolet absorber or a colorant is used, the edge width region of the pressure-sensitive adhesive sheet is satisfactorily cured. be able to.
Further, it is sufficient that the present adhesive sheet itself has photocurability, and it is not always necessary to cure the edge width region by light irradiation. Specifically, the edge width region may be cured by heat.

<How to use this adhesive sheet>
This adhesive sheet can be used as an adhesive sheet after cutting off an edge width region having a high gel fraction.

For example, in the case of the roll-shaped adhesive sheet 2, the release films 11 and 12 are released after rewinding and cutting into an appropriate size and cutting the edge width regions 1A and 1A having a high gel fraction. It can be peeled off and used as an adhesive sheet. Then, for example, after laminating the adhesive sheet 10 so as to sandwich the two image display device constituent members, light, for example, ultraviolet rays are irradiated from at least one image display device constituent member side, and the adhesive is presently adhered through the member. By photocrosslinking the sheet 10 and photocuring it, the two image display device components can be bonded together. The curing method when using the present adhesive sheet 10 is not limited to curing by light irradiation, and other curing methods such as a method of curing by heating can also be used.
Here, examples of the image display device constituent member as an adherend include a surface protection panel, a touch panel, an image display panel, and the like.

<Explanation of words and phrases>
In the present invention, "(meth) acrylic" means acrylic and methacrylic, "(meth) acryloyl" means acryloyl and methacrylic, and "(meth) acrylate" means acrylate and methacrylate.

In general, the boundary between a sheet and a film is not fixed, and it is not necessary to distinguish between the two in the present invention. Therefore, in the present invention, even if the term "film" is used, the term "sheet" is included. Even when referred to, it shall include "film".
Further, when the term "panel" is used, such as an image display panel and a protective panel, it includes a plate, a sheet, and a film.

In the present specification, when "X to Y" (X, Y are arbitrary numbers) is described, it means "X or more and Y or less" and "preferably larger than X" or "preferably larger than X", unless otherwise specified. It also includes the meaning of "smaller than Y".
Further, when described as "X or more" (X is an arbitrary number), it includes the meaning of "preferably larger than X" and is described as "Y or less" (Y is an arbitrary number). In this case, unless otherwise specified, it also includes the meaning of "preferably smaller than Y".

Hereinafter, examples and comparative examples of the present invention will be described.

<Measurement and evaluation method>
First, a method for measuring and evaluating various physical property values of the samples obtained in Examples and Comparative Examples will be described.

(Measurement of gel fraction)
In Examples 1 to 4 and Comparative Examples 1 and 4, which will be described later, the width w [mm] of the photocured edge width region is known. Arbitrarily about 0.05 g is collected from the region having a width w [mm] from the edge toward the center of the sheet, and this is used as a measurement sample in the edge width region, while arbitrarily taken from the central region not photo-cured. About 0.05 g of the sample was collected and used as a measurement sample in the central region.
On the other hand, in Comparative Examples 2 and 3, the sheets were cut out in order from the edge of the sheet on both sides in the lateral direction toward the center of the sheet at intervals of width w [mm] = 0.5 mm, and about 0.05 g was arbitrarily collected from each region. Then, while this was used as a measurement sample in the edge width region, about 0.05 g was arbitrarily collected from the central region not photo-cured, and this was used as a measurement sample in the central region.
For Comparative Examples 2 and 3, the gel fraction in the region of width w [mm] = 1 to 1.5 mm from the edge of the sheet on both sides in the lateral direction to the center of the sheet was also measured and found to be 0%. Since there was, the width w [mm] = 1 mm was set as the edge width region.

Then, each of these measurement samples is wrapped in a bag shape with a stainless steel mesh (# 200) whose mass (X) has been measured in advance, the mouth of the bag is folded and closed, and the mass (Y) of this package is measured. After immersing in 100 ml of ethyl acetate and storing at 23 ° C. for 24 hours in the dark, the package was taken out and heated at 70 ° C. for 4.5 hours to evaporate the attached ethyl acetate, and the mass (Z) of the dried package was obtained. Was measured, and the obtained mass was substituted into the following formula to obtain the value.
Gel fraction [%] = [(ZX) / (YX)] x 100

The same gel fraction measurement was performed for any 6 points, and the standard deviation of the gel fraction was obtained from the obtained values. Regarding how to calculate the standard deviation, first, the average value of the gel fractions at 6 points was calculated. Next, the difference from the obtained average value was calculated for each of the 6 points, and the deviation was calculated. Subsequently, the squared average of the obtained deviations was calculated to obtain the variance. Finally, the positive square root of the variance was calculated to determine the standard deviation of the gel fraction in the edge width region.

(Evaluation of adhesive squeeze out)
The roll-shaped adhesive sheets prepared in Examples and Comparative Examples were exposed to a constant temperature and high humidity environment of 30 ° C. × 90% (RH) for 100 hours, and then the end face of the test piece was observed with a microscope.
Those whose end face condition did not change were evaluated as "○ (good)", and those whose end face was deformed due to the adhesive squeezing out were evaluated as "x (poor)".

(Integrated irradiation dose)
The integrated irradiation amount of UV irradiated in the examples and comparative examples is measured twice by using an ultraviolet integrated photometer "UIT-250" (manufactured by Ushio Denki Co., Ltd.) as an integrated photometer and attaching a light receiving part with a wavelength of 365 nm. The average value was calculated with two significant figures and used as the integrated irradiation amount for each.

<Example 1>
As the (meth) acrylic copolymer (a), 15 parts by mass (18 mol%) of polymethylmethacrylate macromonomer (Tg: 105 ° C.) and butyl acrylate (Tg: −55 ° C.) 81 parts by mass having a number average molecular weight of 2400. Acrylic copolymer (a-1) (weight average molecular weight 230,000) 1 kg obtained by random copolymerization of (75 mol%) and 4 parts by mass (7 mol%) of acrylic acid (Tg: 106 ° C.) and a cross-linking agent. As (b), 90 g of glycerin dimethacrylate (manufactured by Nichiyu Co., Ltd., product name: GMR) (b-1), and as the photopolymerization initiator (c), 2,4,6-trimethylbenzophenone and 4-methylbenzophenone. A resin composition used for the pressure-sensitive adhesive layer was prepared by uniformly mixing 15 g of the mixture (manufactured by Lamberti, product name: Ezacure TZT) (c-1). The glass transition temperature of the obtained resin composition was −5 ° C.

The obtained resin composition was released from a mold release film 11 (manufactured by Mitsubishi Chemical Co., Ltd., product name: Diafoil MRV-V06, thickness: 100 μm) made of a mold release-treated polyethylene terephthalate (PET) film. A release film 12 (a film formed by laminating a release layer having a thickness of 2 μm made of a silicone-based compound on one side of a biaxially stretched isophthalic acid copolymerized PET film having a thickness of 75 μm). By sandwiching and shaping the pressure-sensitive adhesive sheet 10 into a long sheet using a laminator so that the thickness of the pressure-sensitive adhesive sheet 10 was 150 μm, a long pressure-sensitive adhesive sheet 1 with a release film was produced.

As shown in FIGS. 1 and 2, the adhesive sheet 1 with a release film is conveyed in a fixed direction (MD direction) at a transfer speed (line speed) of 20 m / min, and the adhesive sheet 1 with a release film is conveyed in the sheet width direction. Ultraviolet rays (UV) are applied from above to the upper surfaces of the edge width regions 1A and 1A having a width w (curing width in the table) = 5 [mm] from the edge of the sheet toward the center of the sheet at both ends (TD direction). After irradiating and curing the edge width regions 1A and 1A of the pressure-sensitive adhesive sheet 10, the pressure-sensitive adhesive sheet 1 with a release film has a winding tension (winding tension) of 70 N / m per 1 m of film width. The film was wound into a roll to obtain a long roll-shaped adhesive sheet 2 having a total length of 100 m and a roll width of 1000 mm.
The gel content of the pressure-sensitive adhesive sheet 10, that is, the pressure-sensitive adhesive sheet 10 before curing in the pressure-sensitive adhesive sheet 1 with a release film was 0%.

At this time, as shown in FIGS. 1 and 2, the light source 3 is arranged in the vertical upward direction of both side edges of the adhesive sheet 1 with the release film in the width direction (short direction), respectively, and the sheet of the adhesive sheet laminate 1 is arranged. Ultraviolet rays were irradiated from above perpendicular to the upper surface.
As the light source 3, an LED having an output of 7 W / cm ² , an irradiation wavelength of 365 nm, a light diffusion angle of 30 °, and a length in the MD direction (light source length in the table) of 44 mm was used. Further, the distance between the light source 3 and the roll-shaped adhesive sheet 2 (the distance of the light source in the table) was set to 10 mm, and the light was irradiated so that the integrated light amount per unit time was 1600 mJ.

<Example 2>
A roll-shaped adhesive sheet 2 was obtained in the same manner as in Example 1 except that the transport speed (line speed) and the integrated light beam amount per unit time were changed as shown in the table.

<Example 3>
A roll-shaped adhesive sheet 2 was obtained in the same manner as in Example 2 except that the curing width was changed.

<Comparative Example 1>
A roll-shaped adhesive sheet 2 was obtained in the same manner as in Example 2 except that the curing width was changed.

<Comparative Example 2>
As shown in FIG. 3B, the direction of irradiation with light was changed to the sheet surface extension direction, that is, the side surface direction of the adhesive sheet 1 with a release film, and the curing width was changed, as in the second embodiment. A roll-shaped adhesive sheet 2 was obtained.

<Comparative Example 3>
As shown in FIG. 3B, the direction of irradiating light is changed to the sheet surface extension direction, that is, the side surface direction of the adhesive sheet 1 with a release film, and the type of the light source is changed to carry the transport speed (line speed). A roll-shaped adhesive sheet 2 was obtained in the same manner as in Example 2, except that the integrated light amount per unit time and other conditions were changed as shown in the table.

<Example 4>
A roll-shaped adhesive sheet 2 was obtained in the same manner as in Example 2 except that the thickness of the adhesive sheet was changed to 100 μm and the curing width was changed to 35d.

<Comparative Example 4>
A roll-shaped adhesive sheet 2 was obtained in the same manner as in Example 4 except that the curing width was changed to 25d.

From the above examples and the test results conducted by the inventors so far, when the adhesive sheet is wound into a roll and stored at room temperature, it is effective to prevent the adhesive from squeezing out from the end face of the roll. In order to suppress, at least the gel fraction of the cured region, that is, the edge width region is larger than the gel fraction of the pressure-sensitive adhesive sheet in the central region, and the width w [mm] of the edge width region is the thickness of the pressure-sensitive adhesive sheet. It was found that 30d <w needs to be in relation to d [mm].

Claims (14)

An adhesive sheet winding body with a release film, which is a roll of an adhesive sheet with a release film formed by laminating a release film on one side or both sides of the adhesive sheet.
The adhesive sheet has photocurability and has a width w [mm] from the edge of both sides of the sheet in the lateral direction toward the center of the sheet (referred to as "edge width region") and the edge width. The area in the center of the sheet (referred to as the "central area") rather than the area satisfies the following conditions (1) and (2).
Further, an adhesive sheet wound body with a release film, characterized in that the standard deviation of the gel fraction in the edge width region is 3% or less .
(1) The gel fraction of the pressure-sensitive adhesive sheet in the edge width region is larger than the gel fraction of the pressure-sensitive adhesive sheet in the central region.
(2) When the thickness of the adhesive sheet is d [mm], 30d <w <100d is satisfied. The adhesive sheet wound body with a release film according to claim 1, wherein the gel fraction in the edge width region is 15% or more and 100% or less. The adhesive sheet wound body with a release film according to claim 1 or 2, wherein the gel fraction in the central region is 0% or more and less than 15%. The adhesive sheet wound body with a release film according to any one of claims 1 to 3, wherein the thickness d of the adhesive sheet is 0.05 mm to 1 mm. The method for manufacturing an adhesive sheet wound body with a release film according to any one of claims 1 to 4 .
By irradiating the edge width region of the release film-attached pressure-sensitive adhesive sheet, which is made by laminating a release film on one side or both sides of the photocurable pressure-sensitive adhesive sheet, the gel of the pressure-sensitive adhesive sheet in the edge width region is applied. A method for manufacturing an adhesive sheet wound body with a release film, which comprises making the fraction larger than the gel fraction of the adhesive sheet in the central region. The method for manufacturing an adhesive sheet wound body with a release film according to claim 5 , wherein the adhesive sheet with a release film is wound into a roll after being irradiated with light. The adhesive sheet with a release film is characterized by irradiating light from above with respect to the upper surface of the sheet, from below with respect to the lower surface of the sheet, or from both above and below the upper and lower surfaces of the sheet. The method for manufacturing an adhesive sheet wound body with a release film according to claim 5 or 6 . The method for manufacturing an adhesive sheet wound body with a release film according to any one of claims 5 to 7 , wherein the light diffusion angle of the light source that irradiates light is 50 ° or less. The method for manufacturing an adhesive sheet wound body with a release film according to any one of claims 5 to 8 , wherein an LED is used as a light source for irradiating light. The method for producing an adhesive sheet wound body with a release film according to any one of claims 5 to 9 , wherein when the light is irradiated, light having a wavelength of at least 200 nm to 450 nm is irradiated. The method for manufacturing an adhesive sheet wound body with a release film according to any one of claims 5 to 10 , wherein the light is irradiated with an integrated light amount of 1000 mJ / cm ² to 10000 mJ / cm ² per unit area. .. A photocurable adhesive sheet having a width w [mm] from the edge of the sheet toward the center of the sheet (referred to as "edge width region") and a region centered on the sheet from the edge width region (referred to as "edge width region"). The "central region") satisfies the following conditions (1) and (2), and further, the pressure-sensitive adhesive sheet is characterized in that the standard deviation of the gel fraction in the edge width region is 3% or less. ..
(1) The gel fraction of the pressure-sensitive adhesive sheet in the edge width region is larger than the gel fraction of the pressure-sensitive adhesive sheet in the central region.
(2) When the thickness of the adhesive sheet is d [mm], 30d <w <100d is satisfied. The adhesive sheet according to claim 12 , which is a long adhesive sheet. The pressure-sensitive adhesive sheet according to claim 13 , wherein the gel fraction in the edge width region is 15 to 100%.

Images