JP2017171858A - Pressure sensitive adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure sensitive adhesive sheet having high weatherproofness.SOLUTION: A pressure sensitive adhesive sheet 1 includes a film layer 3, an adhesive layer 4 disposed on one side of the film layer 3, and a surface protective layer 2 disposed on the other side of the film layer 3. The film layer 3 contains a first ultraviolet light absorber. The adhesive layer 4 contains a second ultraviolet light absorber. The surface protective layer 2 contains a triazine-type ultraviolet light absorber as a third ultraviolet light absorber. The surface protective layer 2 preferably includes an acrylic urethane resin with a hydrophobic functional group introduced therein. The surface protective layer 2 preferably has 6-15 μm thickness. The first ultraviolet light absorber has an ultraviolet light absorption wavelength range different from an ultraviolet light absorption wavelength range of the second ultraviolet light absorber, and the first ultraviolet light absorber preferably absorbs an ultraviolet light closer to a long wavelength side than the second ultraviolet light absorber.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a pressure-sensitive adhesive sheet that can be bonded to an adherend.

2. Description of the Related Art Conventionally, a marking film that is used by being attached to the surface of a railway vehicle, an automobile, a vending machine or the like has been used. An overlay film for the purpose of surface protection, glossy factory, fading / deterioration prevention and the like may be attached to the surface of the marking film. Such an overlay film and a pressure-sensitive adhesive sheet used as a surface protecting film for an exterior signboard are required to have high weather resistance.
For example, in the following Patent Document 1 and Patent Document 2, a decorative sheet or a resin film is prepared by adding a weather stabilizer such as an ultraviolet absorber to the resin layer in order to achieve high weather resistance. It is described that a weathering stabilizer such as an ultraviolet absorber or a light stabilizer is added to the resin layer.

JP 2008-114560 A JP 2005-015557 A

However, the pressure-sensitive adhesive sheet or the like in which the weather stabilizer is added only to the resin layer described above may not have sufficient weather resistance.
This invention is made paying attention to the above points, and it aims at providing the adhesive sheet which has high weather resistance.

  In order to solve the problems, a pressure-sensitive adhesive sheet according to one embodiment of the present invention includes a film layer, a pressure-sensitive adhesive layer formed on one surface of the film layer, and a surface formed on the other surface of the film layer. A protective layer, wherein the film layer includes a first ultraviolet absorber, the adhesive layer includes a second ultraviolet absorber, and the surface protective layer is a triazine as a third ultraviolet absorber. It contains a system ultraviolet absorber.

  According to one embodiment of the present invention, a pressure-sensitive adhesive sheet having high weather resistance can be obtained.

It is sectional drawing explaining the structure of the adhesive sheet which concerns on embodiment based on this invention. FIG.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view schematically showing the pressure-sensitive adhesive sheet 1 according to this embodiment, and the relationship between the thickness and the planar dimensions, the ratio of the thickness of each layer, and the like are different from the actual ones. Further, the embodiment described below exemplifies a configuration for embodying the technical idea of the present invention, and the technical idea of the present invention is that the material, shape, structure, etc. of the component parts are as follows. It is not something specific. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.

As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 of this embodiment includes a film layer 3, a pressure-sensitive adhesive layer 4 formed on one surface of the film layer 3, and the other surface of the film layer 3 (pressure-sensitive adhesive layer 4 And a surface protective layer 2 formed on a surface opposite to the formation surface.
Hereinafter, with reference to FIG. 1, each layer of the adhesive sheet 1 is demonstrated in detail.

<Film layer>
The film layer 3 is a film formed of a resin material such as a thermoplastic resin containing a first ultraviolet absorber for improving weather resistance. The film layer 3 may be transparent or opaque. The film layer 3 may be colored or uncolored.
A light stabilizer may be added to the film layer 3 in order to prevent the resin material itself from being deteriorated by light, heat, water, or the like. Examples of the thermoplastic resin include polypropylene, polyethylene, polyethylene terephthalate, and polyvinyl chloride, and mixtures, modified products, and polymers thereof.

As a 1st ultraviolet absorber added to the film layer 3, the material which has an ultraviolet absorption wavelength range different from the ultraviolet absorption wavelength range of the 2nd ultraviolet absorber added to the adhesive layer 4 is mentioned. The 1st ultraviolet absorber added to the film layer 3 absorbs the ultraviolet-ray of a different wavelength range (wavelength range which is hard to be absorbed with the adhesive layer 4) from the 2nd ultraviolet absorber added to the adhesive layer 4. be able to.
The first ultraviolet absorber is preferably a material that absorbs ultraviolet rays having a wavelength longer than that of the second ultraviolet absorber. The first ultraviolet absorber preferably absorbs ultraviolet rays having a wavelength of 350 nm or more and 370 nm or less.

  As such a first ultraviolet absorber, for example, a benzotriazole ultraviolet absorber is preferably used. Examples of the benzotriazole ultraviolet absorber include 2- (2-hydroxy-5-tert-butylphenyl) -2H-benzotriazole, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy −3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2- (3-t- Butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3,5-di-t-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3,5- Di-t-amyl-2-hydroxyphenyl) benzotriazole, 2- (2′-hydroxy-5′-octylphenyl) benzotriazole And mixtures thereof, modified products, polymers, and derivatives.

  The number of added parts of the first ultraviolet absorber is 0.1% by mass or more and 50% by mass or less, preferably 0.5% by mass or more and 30% by mass or less with respect to the resin material that is the material of the film layer 3. This is because the ultraviolet absorbing effect is sufficiently exhibited and bleeding out of the ultraviolet absorbent can be suppressed.

Further, as the light stabilizer added to the film layer 3, a hindered amine light stabilizer is preferably used.
As the hindered amine light stabilizer, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) [[3,5-bis (1,1-dimethylethyl) -4-hydroxyphenyl] methyl] butyl Malonate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, methyl (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis [2,2] decanoic acid 2,6,6-tetramethyl-1-octyloxy) -4-piperidinyl] ester and the like, mixtures thereof, modified products, polymers, derivatives and the like.

The film layer 3 can be formed to have a desired thickness. For example, the thickness is preferably 60 μm or more and 100 μm or less. This is because the adhesive film 1 has particularly high strength and weather resistance, and the productivity at the time of manufacturing the film layer 3 is better.
Such a film layer 3 has a light transmittance of 0.5% or less in an ultraviolet region having a wavelength region of 310 nm to 370 nm. Therefore, deterioration of the film layer 3 due to ultraviolet rays can be suppressed.

<Adhesive layer>
The pressure-sensitive adhesive layer 4 is formed of an adhesive containing a second ultraviolet absorber for improving weather resistance. Further, a light stabilizer may be added to the pressure-sensitive adhesive layer 4 in order to prevent the adhesive itself from being deteriorated by light, heat, water or the like. Examples of the adhesive include acrylic adhesives, rubber adhesives, epoxy adhesives, and isocyanate adhesives, but acrylic adhesives are preferably used.

  Examples of the acrylic adhesive include n-butyl (meth) acrylate, hexyl (meth) acrylate, 2-diethylbutyl (meth) acrylate, isooctyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, (Meth) acrylic acid 2-ethylhexyl, (meth) acrylic acid decyl, (meth) acrylic acid dodecyl, (meth) acrylic acid tridecyl ester, etc. (Meth) acrylic acid, itaconic acid, maleic acid, maleic anhydride, hydroxyethyl acrylate, hydroxypropyl acrylate, acrylamide, dimethylacrylamide, methylaminoethyl methacrylate, (meth) acrylic acid, copolymerizable with acrylic ester Copolymers with functional monomers such as methoxyethyl And the like.

Examples of the rubber-based adhesive include natural rubber-based, isoprene rubber-based, styrene-butadiene-based, recycled rubber-based, polyisobutylene-based, and blocks including rubbers such as styrene-isoprene-styrene and styrene-butadiene-styrene. Examples thereof include an adhesive mainly comprising a copolymer.
Examples of the epoxy adhesive include aliphatic chain-modified epoxy resins, hydrocarbon-modified epoxy resins such as cyclopentadiene-modified epoxy resins and naphthalene-modified epoxy resins, elastomer-modified epoxy resins, and silicone-modified epoxy resins.
Examples of the isocyanate-based adhesive include caprolactam-based blocked isocyanate, phenol-based blocked isocyanate, and toluene diisocyanate-based.

  As the above-mentioned adhesive, any of non-crosslinked type and crosslinked type can be used. In the latter case, a crosslinking agent can be added as necessary. As the crosslinking agent, for example, an epoxy compound, an isocyanate compound, a metal chelate compound, a metal alkoxide, a metal salt, an amine compound, a hydrazine compound, an aldehyde compound, or the like can be used alone or in admixture of two or more. .

Examples of the second ultraviolet absorber added to the pressure-sensitive adhesive layer 4 include a material having an ultraviolet absorption wavelength region different from the ultraviolet absorption wavelength region of the first ultraviolet absorber added to the film layer 3. The second ultraviolet absorber added to the pressure-sensitive adhesive layer 4 absorbs ultraviolet rays in a wavelength region different from that of the first ultraviolet absorber added to the film layer 3 (wavelength region difficult to be absorbed by the film layer 3). Can do.
The second ultraviolet absorber is preferably a material that absorbs ultraviolet rays having a shorter wavelength than the first ultraviolet absorber. The second ultraviolet absorber preferably absorbs ultraviolet rays having a wavelength of at least 310 nm and not more than 350 nm.

  As such a second ultraviolet absorber, for example, a triazine-based ultraviolet absorber is preferably used. Examples of the triazine ultraviolet absorber include 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol, 2- [4-[(2- Hydroxy-3-dodecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- [4-[(2-hydroxy- 3-tridecyloxypropyl) oxy] -2-hydroxyphenyl] -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2,4-bis (2,4-dimethylphenyl) ) -6- (2-hydroxy-4-iso-octyloxyphenyl) -s-triazine, mixtures thereof, modified products, polymers, derivatives, and the like.

The added number of the second ultraviolet absorber is 0.1% by mass or more and 50% by mass or less, and preferably 0.5% by mass or more and 30% by mass or less with respect to the adhesive which is the material of the pressure-sensitive adhesive layer 4. This is because the ultraviolet absorbing effect is sufficiently exhibited and bleeding out of the ultraviolet absorbent can be suppressed.
Further, as the light stabilizer added to the pressure-sensitive adhesive layer 4, it is preferable to use the same hindered amine light stabilizer as the light stabilizer added to the film layer 3.

The pressure-sensitive adhesive layer 4 can be formed to a desired thickness, and for example, the thickness is preferably 20 μm or more and 40 μm or less. This is because the pressure-sensitive adhesive film 1 has higher strength and weather resistance, and the productivity during production of the pressure-sensitive adhesive layer 4 is better.
Such an adhesive layer 4 has a light transmittance of 0.5% or less in an ultraviolet region having a wavelength region of 310 nm or more and 370 nm or less. Therefore, deterioration of the film layer 3 due to ultraviolet rays can be suppressed.

<Surface protective layer>
The surface protective layer 2 is formed of a resin material such as a thermoplastic resin containing a third ultraviolet absorber for improving weather resistance. The surface protective layer 2 is a layer transparent to the extent that the film layer 3 can be visually recognized.
The thermoplastic resin used for the surface protective layer 2 is selected in consideration of water resistance and adhesion between the surface protective layer 2 and the film layer 3, and is an acrylic resin having a hydrophobic functional group introduced therein, particularly a hydrophobic functional group. Including acrylic urethane resin. The acrylic urethane resin introduced with a hydrophobic functional group in the present embodiment is obtained by polymerizing monomers having many hydrophobic functional groups. Further, the surface protective layer 2 may contain other thermoplastic resin together with the acrylic urethane resin into which the hydrophobic functional group is introduced. Examples of other thermoplastic resins include polyolefin resins such as polypropylene and polyethylene, mixtures thereof, modified products, and polymers.
When the surface protective layer 2 contains an acrylic resin having a hydrophobic functional group introduced therein (an acrylic urethane resin having a hydrophobic functional group introduced), the water resistance of the surface protective layer 2 is sufficiently increased. The thickness can be reduced. For this reason, the amount of resin material used (the amount of molten resin applied) can be reduced, and the surface protective layer 2 can be easily formed. Moreover, while suppressing the discoloration and fading of the surface protective layer 2 by being exposed to moisture when using the pressure-sensitive adhesive sheet 1, it contributes to the improvement of weather resistance. In addition, a light stabilizer may be added to the surface protective layer 2.

  As a 3rd ultraviolet absorber added to the surface protective layer 2, the triazine type ultraviolet absorber similar to a 2nd ultraviolet absorber is used, for example. In the pressure-sensitive adhesive sheet 1, the surface protective layer 2 contains a triazine-based ultraviolet absorber, so that the surface protective layer 2 that first receives ultraviolet rays efficiently absorbs ultraviolet rays, and the amount of ultraviolet rays received by the film layer 3 and the adhesive layer 4 is reduced. Can be reduced. For this reason, stability of the film layer 3 and the adhesion layer 4 improves dramatically, and the weather resistance of the adhesive sheet 1 improves. The third ultraviolet absorber is a material that absorbs ultraviolet rays having a wavelength different from that of the first ultraviolet absorber. Specifically, the third ultraviolet absorber is a material that absorbs ultraviolet rays having a shorter wavelength than the first ultraviolet absorber. Therefore, a wide range of ultraviolet rays can be absorbed by the film layer 3 containing the first ultraviolet absorber and the surface protective layer 2 containing the third ultraviolet absorber.

The number of added parts of the third ultraviolet absorber is 0.05% by mass or more and 30% by mass or less, preferably 0 with respect to the resin material including the acrylic urethane resin into which the hydrophobic functional group that is the material of the surface protective layer 3 is introduced. 0.05 mass% or more and 25 mass% or less. This is because the ultraviolet absorbing effect is sufficiently exhibited and bleeding out of the ultraviolet absorbent can be suppressed. When a triazine-based ultraviolet absorber is used as the third ultraviolet absorber, the number of added ultraviolet absorbers can be reduced as compared with the case where a benzotriazole-based ultraviolet absorber is used. For this reason, it becomes easy to mix a 3rd ultraviolet absorber with the acrylic urethane resin which introduce | transduced the hydrophobic functional group, and the productivity of an adhesive sheet improves. Moreover, since the addition property of the 3rd ultraviolet absorber with respect to the acrylic urethane resin which introduce | transduced the hydrophobic functional group improves, the quality of the surface protective layer 2 improves and the stability of the adhesive sheet 1 improves. Moreover, when using a triazine type ultraviolet absorber as a 3rd ultraviolet absorber, the surface protection layer 2 can be made thin compared with the case where the benzotriazole type ultraviolet absorber of the same amount addition part is used. For this reason, since formation of the surface protective layer 2 becomes easy and manufacturing time is shortened, productivity of the pressure-sensitive adhesive sheet is improved.
Further, as the light stabilizer added to the surface protective layer 2, it is preferable to use the same hindered amine light stabilizer as the light stabilizer added to the film layer 3.

  The surface protective layer 2 can be formed to a desired thickness, and for example, the thickness is preferably 6 μm to 15 μm. When the thickness of the surface protective layer 2 is in the above range, the weather resistance and water resistance of the pressure-sensitive adhesive sheet 1 are sufficiently high, and the surface protective layer 2 is not too thick. Is prevented and blocking is prevented. Thereby, the fall of the production speed at the time of adhesive sheet manufacture and the fall of a yield can be suppressed, and the productivity of the adhesive sheet 1 can be improved.

<Effect>
The adhesive layer according to the present embodiment as described above has the following effects.
(1) Since the surface protective layer contains a triazine-based ultraviolet absorber as an ultraviolet absorber, the surface protective layer that first receives ultraviolet rays efficiently absorbs ultraviolet rays and reduces the amount of ultraviolet rays received by the film layer and the adhesive layer. can do. For this reason, stability of a film layer or an adhesion layer improves dramatically, and the weather resistance of an adhesive sheet improves.
(2) When the surface protective layer contains an acrylic resin (acrylic urethane resin) into which a hydrophobic functional group has been introduced, the water resistance of the surface protective layer 2 becomes sufficiently high, which contributes to an improvement in weather resistance.
(3) Since the thickness of the surface protective layer can be reduced, the amount of resin material used (the amount of molten resin applied) can be reduced, and the surface protective layer can be easily formed.
(4) When the pressure-sensitive adhesive sheet is used, discoloration of the surface protective layer 2 due to the surface protective layer 2 being exposed to moisture is suppressed.
(5) By adding an ultraviolet absorber to each of the film layer, the pressure-sensitive adhesive layer, and the surface protective layer, ultraviolet rays having different wavelengths can be absorbed in each layer, and ultraviolet rays in a wavelength region that are difficult to be absorbed by any layer. Can be absorbed by other layers. That is, each layer can mutually compensate for the ultraviolet absorption wavelength.
(6) Not only one layer (for example, the surface protective layer) but also other layers (for example, the film layer and the pressure-sensitive adhesive layer) are added with an ultraviolet absorber to suppress bleeding out of the ultraviolet absorber. Connected.
(7) When the film layer contains the thermoplastic resin, deterioration of the pressure-sensitive adhesive sheet when the outer wall or the window becomes high temperature is suppressed.
(8) When the thickness of the surface protective layer is 6 μm or more and 15 μm or less, the weather resistance and water resistance of the pressure-sensitive adhesive sheet are sufficiently high, and the occurrence of blocking during production is prevented, and the productivity of the pressure-sensitive adhesive sheet Can be improved.

  Hereinafter, the adhesive sheet in the present embodiment will be described with specific examples and comparative examples. In addition, this embodiment is not restrict | limited by the following examples and comparative examples.

<Example 1>
(Formation of film)
A melted polypropylene resin (Prime Polymer Co., Ltd., Prime TPO F-3900 (registered trademark)) is mixed with a benzotriazole-based UV absorber and a hindered amine-based light stabilizer that absorb at least 350 nm to 370 nm UV light. did. Subsequently, a molten resin kneaded with the above-described ultraviolet absorber and light stabilizer is extruded at a thickness of 80 μm using an extruder, and becomes a transparent film (hereinafter referred to as a transparent film) to be a film layer of an adhesive sheet. Formed.

(Formation of adhesive layer)
A triazine-based ultraviolet absorber that absorbs ultraviolet rays on a shorter wavelength side, which is different from the benzotriazole-based ultraviolet absorber added to the transparent film, in a two-component cross-linking acrylic adhesive (Arivine BPS 6316, manufactured by Toyo Ink Co., Ltd.) And a hindered amine light stabilizer was added and kneaded. Subsequently, the acrylic adhesive kneaded with the above-described ultraviolet absorber and light stabilizer is dried on the other surface of the transparent film (a surface different from the surface protective layer forming surface) to a thickness of 30 μm. The coating amount was adjusted to be applied. Finally, the coated acrylic adhesive was dried to form an adhesive layer having a thickness of 30 μm.

(Formation of surface protective layer)
A triazine-based ultraviolet absorber that absorbs ultraviolet rays having the same wavelength as that of the triazine-based ultraviolet absorber added to the adhesive layer in a molten thermosetting hydrophobic functional group-introduced acrylic urethane resin (manufactured by DIC Graphics). A hindered amine light stabilizer was added and melt kneaded. The triazine-based ultraviolet absorber was added in an amount of 20% by mass relative to the acrylic urethane resin having a hydrophobic functional group introduced. Subsequently, the acrylic urethane resin introduced with the hydrophobic functional group kneaded with the above-described ultraviolet absorber and light stabilizer is applied on one surface of the transparent film so that the thickness after curing is 6 μm. The coating was adjusted. Finally, the coated acrylic functional group-introduced acrylic urethane resin was cured to form a 6 μm thick surface protective layer.
By the above, the adhesive sheet in which the surface protection layer and the adhesion layer were formed on both surfaces of the transparent film was produced.

<Example 2>
A pressure-sensitive adhesive sheet in which the surface protective layer and the pressure-sensitive adhesive layer were formed on both surfaces of the transparent film was prepared in the same manner as in Example 1 except that the thickness of the surface protective layer after curing was 15 μm.

<Example 3>
A pressure-sensitive adhesive sheet in which a surface protective layer and a pressure-sensitive adhesive layer were formed on both surfaces of a transparent film was prepared in the same manner as in Example 1 except that the thickness of the surface protective layer after curing was 3 μm.

<Example 4>
As the resin material for the surface protective layer, a thermosetting polyfunctional acrylic urethane resin (manufactured by DIC Graphics Co., Ltd.) was used instead of the acrylic urethane resin into which a thermosetting hydrophobic functional group was introduced. Moreover, the surface protective layer was formed so that the thickness after hardening of a surface protective layer might be set to 15 micrometers. Except this, it carried out similarly to Example 1, and produced the adhesive sheet in which the surface protective layer and the adhesion layer were each formed on both surfaces of the transparent film.

<Comparative Example 1>
When forming the surface protective layer, no triazine-based UV absorber is added to the molten acrylic urethane resin into which the thermosetting hydrophobic functional group is introduced, and the surface protective layer is formed so as to have a thickness of 15 μm. Formed. Except this, it carried out similarly to Example 1, and produced the adhesive sheet in which the surface protective layer and the adhesion layer were each formed on both surfaces of the transparent film.

<Comparative example 2>
When forming the surface protective layer, a benzotriazole ultraviolet absorber was used as the ultraviolet absorber instead of the triazine ultraviolet absorber, and the surface protective layer was formed to a thickness of 15 μm. Except this, it carried out similarly to Example 1, and produced the adhesive sheet in which the surface protective layer and the adhesion layer were each formed on both surfaces of the transparent film.

<Comparative Example 3>
When forming the surface protective layer, a thermosetting polyfunctional acrylic urethane resin (manufactured by DIC Graphics Co., Ltd.) was used instead of the acrylic urethane resin into which a thermosetting hydrophobic functional group was introduced as a resin material. Further, a benzotriazole ultraviolet absorber was used as the ultraviolet absorber instead of the triazine ultraviolet absorber, and a surface protective layer was formed so as to have a thickness of 15 μm. Except this, it carried out similarly to Example 1, and produced the adhesive sheet in which the surface protective layer and the adhesion layer were each formed on both surfaces of the transparent film.

[Evaluation]
The following evaluation was performed on the pressure-sensitive adhesive sheets of Examples 1 to 4 and Comparative Examples 1 to 3 described above.

(Accelerated weather resistance test)
An accelerated weather resistance test was performed on the pressure-sensitive adhesive sheets of each Example and each Comparative Example under the following conditions, and the surface of each pressure-sensitive adhesive sheet was confirmed for cracks / cracks and the color of the adherend was confirmed.

(conditions)
Testing machine: Metal weather testing machine (Daipura Metal Weather KU-R5DC1-A manufactured by Daipura Wintes Co., Ltd.)
Condition: Illuminance 65 mW / cm ² , Light (53 ° C., 50% RH) 20 hours, Dew (30 ° C., 95% RH) 4 hours Watering condition: 30 s before and after Dew
The above process was made into 1 cycle, and the accelerated weather resistance test was implemented with respect to each adhesive sheet of an Example and a comparative example for 144 hours.
After the test, the surface of the pressure-sensitive adhesive sheet was checked for cracks and cracks, and the presence or absence of discoloration of the adherend was checked.

In the accelerated weather resistance test, regarding the cracks / cracks on the surface of the pressure-sensitive adhesive sheet, “◎” indicates that no cracks or cracks were generated on the surface, and “○” indicates that cracks or cracks were generated. The case where occurrence occurred was evaluated as “×”.
Further, in the accelerated weather resistance test, regarding the discoloration of the adhesive sheet, “◎” indicates that there was no discoloration, “○” indicates that there was little discoloration, and “×” indicates that there was discoloration. evaluated.

(Evaluation of productivity of adhesive sheet)
Productivity was evaluated about the adhesive sheet of each Example and each comparative example.
Regarding the evaluation of productivity, “◎” indicates that productivity is very good, “◯” indicates that productivity is good, and productivity is inferior (for example, production of an adhesive sheet is impossible) ) Was marked with “x”.

  Table 1 below shows the configurations of Examples and Comparative Examples. The evaluation results are shown in Table 2 below.

(Discussion)
As can be seen from Table 1, the pressure-sensitive adhesive sheets of Examples 1 to 4 containing the triazine-based ultraviolet absorber in the surface protective layer are those of Comparative Examples 1 to 3 in which the surface protective layer does not contain the triazine-based ultraviolet absorber. Compared with the pressure-sensitive adhesive sheet, the evaluation was improved comprehensively.
In the pressure-sensitive adhesive sheet of Comparative Example 1 in which the surface protective layer did not contain the ultraviolet absorber itself, cracks and cracks occurred on the surface of the pressure-sensitive adhesive sheet, and surface discoloration occurred. This is because the surface protective layer does not contain an ultraviolet absorber, and thus the weather resistance of the surface protective layer is significantly reduced.

  Further, the pressure-sensitive adhesive sheets of Comparative Example 2 and Comparative Example 3 containing a benzotriazole ultraviolet absorber as the ultraviolet absorber in the surface protective layer are more susceptible to surface cracks, cracks, and discoloration than the pressure-sensitive adhesive sheet of Comparative Example 1. It can be confirmed that it is suppressed and the weather resistance is improved. However, compared with the pressure-sensitive adhesive sheets of Examples 1 to 4, the weather resistance was not sufficient. Moreover, although the pressure-sensitive adhesive sheet of Comparative Example 2 uses an acrylic urethane resin into which a hydrophobic functional group is introduced as a resin material for forming the surface protective layer, it does not contain a benzotriazole-based ultraviolet absorber, so that it has weather resistance. It was not enough.

On the other hand, the pressure-sensitive adhesive sheets of Examples 1 to 4 containing a triazine-based UV absorber as the UV absorber in the surface protective layer are comprehensively evaluated as compared with the pressure-sensitive adhesive sheets of Comparative Examples 1 to 3. Improved.
In particular, as can be seen from the evaluation of Example 2 and Example 4 in which the thickness of the surface protective layer is the same, the pressure-sensitive adhesive sheet of Example 2 is the pressure-sensitive adhesive of Example 4 using an acrylic urethane resin as the resin material of the surface protective layer. Compared with the sheet, the color fading of the pressure-sensitive adhesive sheet is less likely to occur. This is presumably because the use of an acrylic urethane resin having a hydrophobic functional group introduced into the surface protective layer improved water resistance and suppressed discoloration of the surface protective layer due to exposure to moisture.

Further, as can be seen from the evaluation of Examples 1 to 3 having a surface protective layer containing an acrylic urethane resin into which a hydrophobic functional group has been introduced and a triazine ultraviolet absorber, the thickness of the surface protective layer is reduced. It was also found that sufficient weather resistance and productivity can be obtained.
In particular, when the thickness of the surface protective layer was 3 μm as in the pressure-sensitive adhesive sheet of Example 3, productivity was improved as compared with, for example, Comparative Example 2. This is because when the triazine-based UV absorber is used as the UV absorber as in Example 3, the surface protective layer is formed thinner than when the same amount of added benzotriazole-based UV absorber is used. It is because it can do. The pressure-sensitive adhesive sheet of Example 3 has the same degree of evaluation of surface cracks / crack generation and discoloration as the pressure-sensitive adhesive sheet of Comparative Example 2, and the thickness of the surface protective layer is reduced by using a triazine UV absorber. It was also found that the same level of weather resistance can be realized.

Moreover, it turned out that both the weather resistance and productivity improve more and the high quality is obtained for the adhesive sheet of Example 1 by adjusting thickness appropriately. This is because the surface protective layer is thinner than the adhesive sheet of Example 2 and the productivity is increased, and the surface protective layer is thicker than the adhesive sheet of Example 3 and the weather resistance is improved. .
As described above, the pressure-sensitive adhesive sheet of this embodiment contains a triazine-based ultraviolet absorber in the surface protective layer, like the pressure-sensitive adhesive sheets of Examples 1 to 4. Moreover, it is preferable that the adhesive sheet of this embodiment contains the acrylic urethane resin which introduce | transduced the hydrophobic functional group into the surface protective layer like the adhesive sheet of Example 1- Example 3. FIG. Furthermore, as for the adhesive sheet of this embodiment, it is preferable from a weather resistant viewpoint that the thickness of a surface protective layer is 6 micrometers or more and 15 micrometers or less like the adhesive sheet of Example 1- Example 3.

[Others]
The scope of the present invention is not limited to the illustrated and described exemplary embodiments, but also includes all embodiments that provide equivalent effects to those intended by the present invention. Further, the scope of the invention is not limited to the combinations of features of the invention defined by the claims, but can be defined by any desired combination of specific features among all the disclosed features.

DESCRIPTION OF SYMBOLS 1 Adhesive sheet 2 Surface protective layer 3 Film layer 4 Adhesive layer

Claims (5)

A film layer;
An adhesive layer formed on one surface of the film layer;
A surface protective layer formed on the other surface of the film layer;
With
The film layer includes a first ultraviolet absorber,
The pressure-sensitive adhesive layer contains a second ultraviolet absorber,
The pressure-sensitive adhesive sheet, wherein the surface protective layer contains a triazine-based ultraviolet absorber as a third ultraviolet absorber.   The pressure-sensitive adhesive sheet according to claim 1, wherein the surface protective layer contains an acrylic urethane resin into which a hydrophobic functional group is introduced.   The pressure-sensitive adhesive sheet according to claim 1 or 2, wherein the surface protective layer has a thickness of 6 µm or more and 15 µm or less.   The pressure-sensitive adhesive sheet according to any one of claims 1 to 3, wherein an ultraviolet absorption wavelength region of the first ultraviolet absorber is different from an ultraviolet absorption wavelength region of the second ultraviolet absorber.   5. The pressure-sensitive adhesive sheet according to claim 4, wherein the first ultraviolet absorber absorbs ultraviolet rays having a wavelength longer than that of the second ultraviolet absorber.

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