JP6686609B2 - Adhesive sheet - Google Patents

Description

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

2. Description of the Related Art Conventionally, a marking film that is used by being attached to the surface of, for example, a railway vehicle, an automobile, a vending machine or the like has been used. An overlay film may be attached to the surface of the marking film for the purpose of surface protection, gloss factory, and prevention of discoloration and deterioration. High weather resistance is required for such an overlay film and an adhesive sheet used as a surface protection film for an exterior signboard.
For example, in Patent Documents 1 and 2 below, in order to realize high weather resistance of a decorative sheet or a resin film, a weather resistant stabilizer such as an ultraviolet absorber is added to a resin layer to manufacture the same. It is described that a weather resistance 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, in the case of the pressure-sensitive adhesive sheet or the like in which the weather resistance stabilizer is added only to the resin layer, the adhesion between the surface protective layer and the film layer may not be sufficient.
The present invention has been made paying attention to the above points, and an object thereof is to provide a pressure-sensitive adhesive sheet having high adhesion between the surface protective layer and the film layer.

In order to solve the problems, the pressure-sensitive adhesive sheet according to one aspect of the present invention is a film layer, a pressure-sensitive adhesive layer formed on one surface of the film layer, and a surface protective layer formed on the other surface of the film layer. The film layer includes a first ultraviolet absorber and isotactic polypropylene as a resin material, the adhesive layer includes a second ultraviolet absorber, and the surface protective layer includes a third ultraviolet absorber. look containing a triazine-based ultraviolet absorber as the ultraviolet absorber, the film layer, the pressure-sensitive adhesive sheet, wherein the resin material, that contains isotactic polypropylene to 100 wt% to 95 wt%.

  According to one aspect of the present invention, it is possible to obtain a pressure-sensitive adhesive sheet having high adhesion between the surface protective layer and the film layer.

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

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 the present embodiment, and the relationship between the thickness and the plane dimension, the thickness ratio of each layer, and the like are different from the actual ones. Further, the embodiments described below exemplify 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 components are as follows. Not specific to a thing. Various changes can be added to the technical idea of the present invention within the technical scope defined by the claims described in the claims.

As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 of the present embodiment has 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 (the pressure-sensitive adhesive layer 4). The surface protection layer 2 formed on the surface opposite to the formation surface).
Hereinafter, with reference to FIG. 1, each layer of the pressure-sensitive adhesive sheet 1 will be described 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 deterioration of the resin material itself due to light, heat, water and the like.

The film layer 3 contains polypropylene having high stereoregularity as a resin material. In the present embodiment, "highly stereoregular polypropylene" is specifically isotactic polypropylene, all the methyl groups of the propylene side chain are oriented in the same direction, and propylene is head-to-tail bonded. Refers to the structure that exists.
In addition, the film layer 3 may include polypropylene having low stereoregularity as a resin material. In the present embodiment, the “low stereoregularity polypropylene” is specifically syndiotactic polypropylene, and refers to a structure in which methyl groups of propylene side chains are regularly and alternately directed in different directions. "
Furthermore, the film layer 3 may contain a thermoplastic resin such as polyethylene, polyethylene terephthalate, polyvinyl chloride, or the like, or a mixture, modified product, or polymer thereof as a resin material.

Thereby, the hardness of the surface of the film layer 3 can be improved and the scratch resistance of the pressure-sensitive adhesive sheet 1 as a whole can be improved. Moreover, the dimensional stability of the film layer 3 can be improved. Furthermore, since the corners of the film layer 3 can be prevented from rolling up easily, the adhesive layer 4 can be prevented from peeling off from the non-adhesive body. Therefore, the pressure-sensitive adhesive sheet 1 of the present embodiment has extremely high stability during use. In particular, when the non-adhesive body is flat, the stability of the pressure-sensitive adhesive sheet 1 during use is remarkably increased.
Further, the film layer 3 preferably contains 95% by weight or more and 100% by weight or less of polypropylene having high stereoregularity in the resin material. By containing polypropylene having high stereoregularity within this range, the hardness of the surface of the film layer 3 is further improved, and the scratch resistance of the entire pressure-sensitive adhesive sheet 1 is further improved.

Examples of the first ultraviolet absorber added to the film layer 3 include materials having an ultraviolet absorption wavelength region different from the ultraviolet absorption wavelength region of the second ultraviolet absorber added to the pressure-sensitive adhesive layer 4. The first ultraviolet absorber added to the film layer 3 absorbs ultraviolet rays in a wavelength region different from that of the second ultraviolet absorber added to the pressure-sensitive adhesive layer 4 (wavelength region difficult to be absorbed by the pressure-sensitive 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 at least ultraviolet light having a wavelength of 350 nm or more and 370 nm or less.

  As such a first UV absorber, for example, a benzotriazole-based UV absorber is preferably used. Examples of the benzotriazole-based ultraviolet absorber include 2- (2-hydroxy-5-t-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 Etc., and mixtures, modified products, polymers and derivatives thereof.

  The added number of 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 based on the resin material that is the material of the film layer 3. This is because the ultraviolet absorbing effect can be sufficiently exerted and the bleed-out of the ultraviolet absorbent can be suppressed.

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 is used. Malonate, bis (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, methyl (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis [2,2] decanedioate 2,6,6-Tetramethyl-1-octyloxy) -4-piperidinyl] ester and the like, and mixtures, modified products, polymers and derivatives thereof are mentioned.

The film layer 3 can be formed to have a desired thickness, but the thickness is preferably 60 μm or more and 100 μm or less, for example. This is because the pressure-sensitive adhesive film 1 has particularly high scratch resistance, 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 the ultraviolet region having a wavelength range of 310 nm or more and 370 nm or less. 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 deterioration of the adhesive itself due to light, heat, water and the like. Examples of the adhesive include acrylic adhesives, rubber adhesives, epoxy adhesives, isocyanate adhesives, and the like, and acrylic adhesives are preferably used.

  As the acrylic adhesive, n-butyl (meth) acrylate, hexyl (meth) acrylate, 2-diethylbutyl (meth) acrylate, isooctyl (meth) acrylate, 2-methoxyethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, and the like, and one or more types of (meth) acrylic acid esters, and those (meth) (Meth) acrylic acid copolymerizable with acrylic acid ester, itaconic acid, maleic acid, maleic anhydride, hydroxyethyl acrylate, hydroxypropyl acrylate, acrylamide, dimethylacrylamide, methylaminoethyl methacrylate, (meth) acrylic acid 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 adhesives and blocks containing rubber such as styrene-isoprene-styrene and styrene-butadiene-styrene. Examples of the adhesive include a copolymer as a main component.
Examples of the epoxy adhesive include hydrocarbon modified epoxy resin such as fatty chain modified epoxy resin, cyclopentadiene modified epoxy resin and naphthalene modified epoxy resin, elastomer modified epoxy resin and silicone modified epoxy resin.
Examples of the isocyanate-based adhesive include caprolactam-based blocked isocyanate, phenol-based blocked isocyanate, and toluene diisocyanate-based adhesive.

  As the adhesive as described above, both non-cross-linking type and cross-linking type can be used. In the latter case, a crosslinking agent can be added if necessary. As the cross-linking 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 combination of two or more. .

Examples of the second ultraviolet absorber added to the pressure-sensitive adhesive layer 4 include materials 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 (a wavelength region difficult to be absorbed by the film layer 3). You can
The second ultraviolet absorber is preferably a material that absorbs ultraviolet rays on the shorter wavelength side than the first ultraviolet absorber. The second ultraviolet absorber preferably absorbs at least ultraviolet light having a wavelength of 310 nm or more and 350 nm or less.

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

The number of parts of the second ultraviolet absorber added 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, based on the adhesive that is the material of the pressure-sensitive adhesive layer 4. This is because the ultraviolet absorbing effect can be sufficiently exerted and the bleed-out of the ultraviolet absorbent can be suppressed.
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 have a desired thickness, but the thickness is preferably 20 μm or more and 40 μm or less, for example. This is because the pressure-sensitive adhesive film 1 has higher strength and weather resistance, and the productivity at the time of manufacturing the pressure-sensitive adhesive layer 4 is better.
Such a pressure-sensitive adhesive layer 4 has a light transmittance of 0.5% or less in the ultraviolet range of 310 nm to 370 nm in the wavelength range. Therefore, deterioration of the film layer 3 due to ultraviolet rays can be suppressed.

<Surface protection 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 transparent layer so 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 to the film layer 3 of the surface protective layer 2, and an acrylic resin having a hydrophobic functional group introduced therein, particularly a hydrophobic functional group. It contains acrylic urethane resin. The acrylic urethane resin in which the hydrophobic functional group is introduced in the present embodiment is obtained by polymerizing a monomer having a large number of hydrophobic functional groups. In addition, the surface protective layer 2 may contain other thermoplastic resin together with the acrylic urethane resin having the hydrophobic functional group introduced therein. Examples of other thermoplastic resins include polyolefin resins such as polypropylene and polyethylene, and mixtures, modified products and polymers thereof.
Since the surface protective layer 2 contains an acrylic resin having a hydrophobic functional group introduced (acrylic urethane resin having a hydrophobic functional group introduced), the water resistance of the surface protective layer 2 is sufficiently high and the surface protective layer 2 Since the thickness can be reduced, the amount of resin material used (the amount of molten resin applied) can be reduced and the surface protection layer 2 can be easily formed. Further, it suppresses discoloration of the surface protective layer 2 due to exposure to water when the pressure-sensitive adhesive sheet 1 is used, and contributes to improvement of weather resistance. Further, a light stabilizer may be added to the surface protective layer 2.

As the third ultraviolet absorber added to the surface protective layer 2, for example, the same triazine-based ultraviolet absorber as the second ultraviolet absorber is used. Since the surface protective layer 2 in the pressure-sensitive adhesive sheet 1 contains the triazine-based ultraviolet absorber, the surface protective layer 2 that first receives the ultraviolet rays can efficiently absorb the ultraviolet rays and improve the stability of the surface protective layer. At this time, since the surface protective layer 2 having high stability against ultraviolet rays is formed on the surface of the film layer 3 containing polypropylene having high stereoregularity and having high dimensional stability, the adhesion between the film layer and the surface protective layer is improved. To do.
In addition, since the surface protective layer 2 of the pressure-sensitive adhesive sheet 1 contains the triazine-based ultraviolet absorber, the surface protective layer 2 that first receives the ultraviolet rays efficiently absorbs the ultraviolet rays, and the ultraviolet rays received by the film layer 3 and the adhesive layer 4 The amount can be reduced. Therefore, the stability of the film layer 3 and the adhesive layer 4 is dramatically improved, and the weather resistance of the adhesive sheet 1 is improved. 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 on the shorter wavelength side 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 third UV absorber is added in an amount of 0.05% by mass or more and 30% by mass or less, preferably 0% by mass or less with respect to the resin material containing the acrylic urethane resin having the hydrophobic functional group, which is the material of the surface protective layer 3. It is 0.05% by mass or more and 25% by mass or less. This is because the ultraviolet absorbing effect can be sufficiently exerted and the bleed-out of the ultraviolet absorbent can be suppressed. When a triazine-based UV absorber is used as the third UV absorber, the number of UV absorbers added can be reduced compared to the case where a benzotriazole-based UV absorber is used. Therefore, it becomes easy to mix the third ultraviolet absorber with the acrylic urethane resin having the hydrophobic functional group introduced therein, and the productivity of the pressure-sensitive adhesive sheet is improved. Further, since the addition property of the third ultraviolet absorber to the acrylic urethane resin having the hydrophobic functional group introduced therein is improved, the quality of the surface protective layer 2 is improved and the stability of the pressure-sensitive adhesive sheet 1 is improved. Further, when the triazine-based UV absorber is used as the third UV absorber, the surface protective layer 2 can be made thinner than when the same amount of benzotriazole-based UV absorber is used. Therefore, the surface protective layer 2 is easily formed and the manufacturing time is shortened, so that the productivity of the pressure-sensitive adhesive sheet is improved.
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 protection layer 2 can be formed to have a desired thickness, but the thickness is preferably 6 μm or more and 15 μm or less, for example. 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, so that the dryness of the surface protective layer 2 during production is high. To prevent blocking from occurring. As a result, it is possible to suppress a decrease in production speed and a decrease in yield at the time of manufacturing the pressure-sensitive adhesive sheet, and improve the productivity of the pressure-sensitive adhesive sheet 1.

<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 the ultraviolet rays can efficiently absorb the ultraviolet rays and improve the stability of the surface protective layer. . Further, since the film layer contains polypropylene having high stereoregularity as the resin material, the dimensional stability of the film layer is improved. Therefore, the adhesion between the film layer having high dimensional stability and the surface protective layer having high stability against ultraviolet rays is improved.
(2) Since the surface protective layer contains a triazine-based ultraviolet absorber as an ultraviolet absorber, the surface protective layer that first receives the ultraviolet light efficiently absorbs the ultraviolet light, and the amount of the ultraviolet light received by the film layer and the adhesive layer is reduced. can do. Therefore, the stability of the film layer and the adhesive layer is dramatically improved, and the weather resistance of the adhesive sheet 1 is improved.
(3) Since the film layer contains polypropylene having a high stereoregularity as the resin material, the hardness of the surface of the film layer can be improved and the scratch resistance of the entire pressure-sensitive adhesive sheet can be improved.

(4) Since the film layer contains polypropylene having a high stereoregularity as the resin material, the corners of the film layer can be prevented from rolling up easily, so that the adhesive layer can be prevented from peeling from the non-adhesive body. .
(5) Since the surface protective layer contains an acrylic resin having a hydrophobic functional group introduced (acrylic urethane resin having a hydrophobic functional group introduced), the surface protective layer has sufficiently high water resistance and improved weather resistance. Contribute to.
(6) 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.

(7) When the pressure-sensitive adhesive sheet is used, the discoloration of the surface protective layer 2 due to the exposure of the surface protective layer to moisture is suppressed.
(8) When the film layer contains polypropylene having high stereoregularity in the resin material in an amount of 95% by weight or more and 100% by weight or less, the hardness of the surface of the film layer is further improved and the scratch resistance of the entire pressure-sensitive adhesive sheet is further improved. improves.
(9) When the thickness of the film layer is 60 μm or more and 100 μm or less, the pressure-sensitive adhesive film has particularly high scratch resistance, strength and weather resistance, and the productivity during production of the film layer becomes better.
(10) By adding an ultraviolet absorber to each of the film layer, the pressure-sensitive adhesive layer and the surface protective layer, it is possible to absorb ultraviolet rays having different wavelengths in each layer, and ultraviolet rays in a wavelength range that is difficult to be absorbed in any of the layers. Can be absorbed by other layers. That is, the respective layers can mutually supplement the absorption wavelength of ultraviolet rays.

(11) The UV absorber is added not only to one layer (for example, the surface protective layer) but also to other layers (for example, the film layer and the pressure-sensitive adhesive layer), thereby suppressing the bleed-out of the UV absorber. Connect
(12) By including the thermoplastic resin in the film layer, deterioration of the pressure-sensitive adhesive sheet when the outer wall, the window, or the like becomes hot is suppressed.
(13) 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 is improved. Can be improved.

Hereinafter, the pressure-sensitive adhesive sheet in the present embodiment will be described with reference to specific examples and comparative examples. The present embodiment is not limited to the following examples and comparative examples.
<Example 1>
(Formation of film)
A benzotriazole-based ultraviolet absorber and a hindered amine-based light stabilizer that absorb at least a wavelength of 350 nm to 370 nm of ultraviolet light are added to a melted polypropylene resin A (Prime Polymer Co., Ltd., Prime Polypro E-2000GV (registered trademark)) to mix it. Forged Subsequently, a molten resin prepared by kneading the above-mentioned ultraviolet absorber and light stabilizer was extruded with an extruder to a thickness of 80 μm to form a transparent film (hereinafter referred to as a transparent film). Here, the polypropylene resin A corresponds to the above-mentioned "high stereoregularity" polypropylene resin.

(Formation of adhesive layer)
A triazine-based UV absorber that absorbs shorter wavelength UV rays, which is different from the benzotriazole-based UV absorber added to the transparent film in the two-component crosslinkable acrylic adhesive (Alibine BPS 6316, manufactured by Toyo Ink Co., Ltd.). And a hindered amine light stabilizer were added and kneaded. Subsequently, the acrylic adhesive obtained by kneading the above-mentioned ultraviolet absorber and light stabilizer was applied to the other surface of the transparent film (the surface different from the surface protective layer forming surface) so that the thickness after drying was 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 protection layer)
A triazine-based UV absorber that absorbs UV light having the same wavelength as that of the triazine-based UV absorber added to the adhesive layer, to a melted thermosetting acrylic urethane resin (manufactured by DIC Graphics Co., Ltd.) into which a hydrophobic functional group is introduced, and A hindered amine light stabilizer was added and melt-kneaded. The triazine-based ultraviolet absorber was added in an amount of 20% by mass with respect to the acrylic urethane resin having a hydrophobic functional group. Subsequently, a coating amount of an acrylic urethane resin having a hydrophobic functional group introduced, which is obtained by kneading the ultraviolet absorber and the light stabilizer described above, is formed on one surface of the transparent film so that the thickness after curing is 6 μm. Was adjusted and coated. Finally, the coated acrylic urethane resin having the introduced hydrophobic functional group was cured to form a surface protective layer having a thickness of 6 μm.
As described above, 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 produced.

<Example 2>
An adhesive sheet of Example 2 was produced in the same manner as in Example 1 except that the thickness of the transparent film was 60 μm.

<Example 3>
An adhesive sheet of Example 3 was produced in the same manner as in Example 1 except that the thickness of the transparent film was 100 μm.

<Example 4>
An adhesive sheet of Example 4 was produced in the same manner as in Example 1 except that the thickness of the transparent film was 40 μm.

<Example 5>
An adhesive sheet of Example 5 was produced in the same manner as in Example 1 except that the thickness of the transparent film was 120 μm.

<Comparative Example 1>
A pressure-sensitive adhesive sheet of Comparative Example 1 was produced in the same manner as in Example 1 except that polypropylene resin B (Prime Polymer Co., Ltd., Prime TPO F-3900) was used instead of the polypropylene resin A used in forming the transparent film. . Here, the polypropylene resin B corresponds to the above-mentioned "low stereoregularity" polypropylene resin.

[Evaluation]
The following evaluations were performed for the pressure-sensitive adhesive sheets of Examples 1 to 5 and Comparative Example 1 described above.

(Scratch resistance test)
A pencil hardness test was performed on the pressure-sensitive adhesive sheets of Examples and Comparative Examples, and the scratch resistance of each pressure-sensitive adhesive sheet was evaluated. The pencil hardness test was carried out according to the scratch hardness (pencil method) shown in JIS K 5600 of Japanese Industrial Standards.
In the scratch resistance test, the case where the maximum hardness at which the coating film does not come off is B or more is "○", the maximum hardness at which the coating film does not come off is 2B or more, and the maximum hardness without dents is 3B or less. Δ ”, the case where the maximum hardness at which the coating film did not peel off was 4 B or less was evaluated as“ x ”.

(Accelerated weathering test)
An accelerated weather resistance test was performed on the pressure-sensitive adhesive sheets of Examples and Comparative Examples under the following conditions.

(conditions)
Tester: Metal weather tester (Daipla Wintes Co., Ltd., Diepla Metalweather KU-R5DC1-A)
Conditions: Illuminance of 65 mW / cm2, Light (53 ° C, 50% RH) for 20 hours, Dew (30 ° C, 95% RH) for 4 hours Watering condition: 30 seconds before and after Dew
Using the above treatment as one cycle, an accelerated weather resistance test was performed for each of the pressure-sensitive adhesive sheets of Examples and Comparative Examples for 144 hours.
After the test, the surface of the pressure-sensitive adhesive sheet was checked for cracks and cracks and the adherend was checked for discoloration.

  In the accelerated weather resistance test, "○" indicates that the adhesive sheet was not peeled off from the non-adhesive body, "△" when the adhesive sheet was slightly peeled off from the non-adhesive body, and the corners of the adhesive sheet were greatly curled up. The case where the adhesive body was largely peeled off was evaluated as "x".

(Evaluation of adhesive sheet productivity)
The productivity of the pressure-sensitive adhesive sheets of Examples and Comparative Examples was evaluated.
Regarding the evaluation of the productivity, the case where the productivity was good was evaluated as “◯”, and the case where the productivity was inferior (for example, the production of the adhesive sheet was impossible) was evaluated as “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 5 in which the transparent film contained polypropylene A, which has high stereoregularity, and the surface protective layer was used, were polypropylene with low stereoregularity. Compared with the pressure-sensitive adhesive sheet of Comparative Example 1 using B, the scratch resistance was significantly improved and the weather resistance was also improved.

Further, from the comparison of Examples 1 to 3 and Example 5 with Example 4, when the thickness of the film layer was 60 μm or more, the scratch resistance was higher than when the thickness was 40 μm. . It is considered that this is because the strength against scratching was improved by the thickness of the film layer being a certain thickness or more.
Further, from the comparison between Example 1 to Example 4 and Example 5, the productivity was improved when the thickness of the film layer was 100 μm or less compared with the case where the thickness was 120 μm. It is considered that this is because when the thickness of the film layer is not more than a certain value, curing at the time of forming the film layer becomes faster and handling becomes easier.

  As described above, the pressure-sensitive adhesive sheet of the present embodiment contains polypropylene having high stereoregularity, like the pressure-sensitive adhesive sheets of Examples 1 to 5. Further, in the pressure-sensitive adhesive sheet of the present embodiment, like the pressure-sensitive adhesive sheets of Examples 1 to 3, the film layer having a thickness of 60 μm or more and 100 μm or less has both scratch resistance, weather resistance and productivity. It is preferable from the viewpoint.

[Other]
The scope of the invention is not limited to the exemplary embodiments shown and described, but also includes all embodiments which bring about an effect equivalent to the object of the invention. Moreover, the scope of the present invention is not limited to the combination of inventive features defined by the claims, but can be defined by any desired combination of specific features of each and every disclosed feature.

1 Adhesive sheet 2 Surface protective layer 3 Film layer 4 Adhesive layer

Claims (6)

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,
Equipped with
The film layer contains a first ultraviolet absorber and isotactic polypropylene as a resin material,
The pressure-sensitive adhesive layer contains a second ultraviolet absorber,
The surface protective layer is observed containing a triazine-based ultraviolet absorber as the third ultraviolet absorbent,
The pressure-sensitive adhesive sheet , wherein the film layer contains 95% by weight or more and 100% by weight or less of isotactic polypropylene in a resin material .   The pressure-sensitive adhesive sheet according to claim 1, wherein the surface protective layer contains an acrylic urethane resin having a hydrophobic functional group introduced therein.   The pressure-sensitive adhesive sheet according to claim 1, 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 the film layer has a thickness of 60 µm or more and 100 µm or less. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4 , wherein an ultraviolet absorption wavelength range of the first ultraviolet absorber is different from an ultraviolet absorption wavelength range of the second ultraviolet absorber. The pressure-sensitive adhesive sheet according to claim 5 , wherein the first ultraviolet absorber absorbs ultraviolet rays having a wavelength longer than that of the second ultraviolet absorber.

Images