JP6535924B2 - Window film - Google Patents

Description

  The present invention relates to window films.

  Window film is an adhesive film attached to window glass of automobiles, buildings, etc. for the purpose of ultraviolet ray cutting in sunlight, preventing flying insects, protecting privacy, crime prevention, prevention of scattering of glass, decoration, etc. , Widely used.

  By the way, the image seen through the window film in a state of being stuck to glass may not be clear and may look like a yellowish skin (mottled). This phenomenon is caused by the occurrence of irregularities on the surface of the adhesive layer of the window film. Window films that develop on the skin may lead to a reduction in product appeal in the market as having a poor appearance.

  It is considered that the peeling force of the separate material with respect to the pressure-sensitive adhesive layer is too high as one of the causes of the occurrence of unevenness on the surface of the pressure-sensitive adhesive layer of the window film. As a window film for preventing the generation of a skin of a wound, for example, Patent Document 1 proposes a pressure-sensitive adhesive film characterized in that the peeling force of the separate material to the pressure-sensitive adhesive layer is 1.0 to 10.0 gf / 25 mm. There is.

Japanese Patent Application Laid-Open No. 11-80684

  In the process of storing the window film in a rolled state in the manufacturing process of the window film, the inventors of the present invention adhere to the window film by the pressure applied to the core of the rolled window film roll. It was found that the agent layer was deformed, and that yuzu skin was generated.

  In addition, the present inventors have found that conventional window films have a reduced generation of skin and those prone to develop skin, and a window film with reduced generation of skin is an adhesive. It has been found that the content of methyl acrylate monomer units in the acrylic copolymer of the layer tends to be insufficient.

It is conceivable to use a triazine-based ultraviolet absorber capable of effectively blocking ultraviolet light having a wavelength of about 300 to 400 nm in the pressure-sensitive adhesive layer in order to prevent the ultraviolet absorption and the flying insect attraction.
Furthermore, the inventors include a triazine-based UV absorber in the pressure-sensitive adhesive layer for the purpose of imparting excellent UV absorbing / cutting performance / flying insect attraction preventing performance in the window film in which the occurrence of the skin of this zygote is reduced. When the matter was tried, it was found that there are those in which the pressure-sensitive adhesive layer is likely to cause white turbidity and those in which the whitening does not occur.

  Then, an object of this invention is to provide the window film in which generation | occurrence | production of the orange peel was reduced, the cloudiness of the adhesive layer could be prevented, and the ultraviolet absorption capability was provided in the adhesive layer.

Ｒ^１２、Ｒ^２２及びＲ^３２は、独立に、水酸基、アルキル基、アルキルオキシ基又はアルキルオキシカルボニルアルキルオキシ基であって、Ｒ^１２、Ｒ^２２及びＲ^３２のうち少なくとも一つは水酸基である。
Ｒ^１３、Ｒ^２３及びＲ^３３は、独立に、水素原子又はアルキル基であって、水素原子又は炭素数１〜８のアルキル基であってもよく、水素原子又はメチル基であってもよく、水素原子であってもよい。
Ｒ^１４、Ｒ^２４及びＲ^３４は、独立に、水酸基、アルキルオキシ基、アルキル基、ヒドロキシアルキルオキシ基、アルキルオキシカルボニルアルキルオキシ基、３−アルキルオキシ−２−ヒドロキシ−プロピルオキシ基又はアルキルカルボニルオキシ基である。
（３）前記粘着剤層はアクリル系共重合体を主成分として含有し、前記アクリル系共重合体は、架橋性の官能基を有しない炭素数４〜５の重合性モノマー単位を、アクリル系共重合体の固形分を基準として１０〜７０質量％含有し、
前記粘着剤層の７０℃における貯蔵弾性率が１６〜８０ｋＰａである、（１）又は（２）に記載のウィンドウフィルム。
（４）幅２５ｍｍに切断したウィンドウフィルムを、２ｋｇローラーを使用して圧着回数一往復でフロートガラス板に圧着し、２３℃、相対湿度５０％の環境下で２４時間放置後に、剥離速度３００ｍｍ／分、剥離角度１８０°で測定した粘着力が１０〜１５Ｎ／２５ｍｍである、（１）〜（３）のいずれか一項に記載のウィンドウフィルム。
（５）前記アクリル系共重合体の重量平均分子量が、５００，０００〜９００，０００である、（１）〜（４）のいずれか一項に記載のウィンドウフィルム。 The present invention is as follows.
(1) A window film having a substrate and an adhesive layer provided on the substrate,
The pressure-sensitive adhesive layer contains an acrylic copolymer and a triazine ultraviolet absorber.
The acrylic copolymer contains 1 to 20% by mass of a methyl acrylate monomer unit based on the solid content of the acrylic copolymer,
The pressure-sensitive adhesive layer contains the triazine-based ultraviolet absorber in an amount of 10 to 20 parts by mass with respect to 100 parts by mass of the acrylic copolymer.
Using an image clarity measuring device in accordance with JIS K 7374: 2007, install the window film with the adhesive layer facing the light source on the sample table, and set the sample table angle 45 degrees, transmission mode, comb width 0.125 mm Window film whose measured image clarity is 80 to 100%.
(2) The window film as described in (1) in which the said triazine type ultraviolet absorber is represented with the following general formula (A-1).

R ¹² , R ²² and R ³² are each independently a hydroxyl group, an alkyl group, an alkyloxy group or an alkyloxycarbonylalkyloxy group, and at least one of R ¹² , R ²² and R ³² is a hydroxyl group.
R ¹³ , R ²³ and R ^{33 each} independently represent a hydrogen atom or an alkyl group, and may be a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and may be a hydrogen atom or a methyl group, It may be a hydrogen atom.
R ¹⁴ , R ²⁴ and R ³⁴ independently represent a hydroxyl group, an alkyloxy group, an alkyl group, a hydroxyalkyloxy group, an alkyloxycarbonylalkyloxy group, a 3-alkyloxy-2-hydroxy-propyloxy group or an alkylcarbonyloxy It is a group.
(3) The pressure-sensitive adhesive layer contains an acrylic copolymer as a main component, and the acrylic copolymer contains an acrylic monomer based on a polymerizable monomer unit having 4 to 5 carbon atoms which does not have a crosslinkable functional group. 10 to 70% by mass based on the solid content of the copolymer,
The window film as described in (1) or (2) whose storage elastic modulus at 70 degrees C of the said adhesive layer is 16-80 kPa.
(4) A window film cut to a width of 25 mm is crimped to a float glass plate by one reciprocation using a 2 kg roller, and after leaving for 24 hours under an environment of 23 ° C and a relative humidity of 50%, the peeling speed is 300 mm The window film according to any one of (1) to (3), wherein the adhesion measured at a peel angle of 180 ° / min and the peel strength is 10 to 15 N / 25 mm.
(5) The window film according to any one of (1) to (4), wherein the weight average molecular weight of the acrylic copolymer is 500,000 to 900,000.

  According to the present invention, it is possible to provide a window film which can reduce the occurrence of acne skin, can prevent whitening of the pressure-sensitive adhesive layer, and has an excellent ultraviolet absorbing performance.

  In one embodiment, the present invention is a window film having a substrate and an adhesive layer provided on the substrate, wherein the adhesive layer is an acrylic copolymer and a triazine ultraviolet absorber. And the acrylic copolymer contains a methyl acrylate monomer unit in an amount of 1 to 20% by mass based on the solid content of the acrylic copolymer, and the pressure-sensitive adhesive layer contains the triazine-based ultraviolet absorber 10-20 mass parts are contained with respect to 100 mass parts of said acrylic copolymers.

  In order to prevent the development of acne skin, it is necessary for the acrylic copolymer used in the pressure-sensitive adhesive layer to contain a large number of relatively polar methyl acrylate monomer units. However, when the methyl acrylate monomer unit is excessively contained in the acrylic copolymer, it tends to be clouded due to the steric hindrance of the triazine ultraviolet absorber used in the pressure-sensitive adhesive layer. In the window film of the present invention in which the ultraviolet ray absorbing ability is imparted to the pressure-sensitive adhesive layer, the acrylic copolymer contains a methyl acrylate monomer unit in an amount of 1 to 20% by mass based on the solid content of the acrylic copolymer. The pressure-sensitive adhesive layer contains 10 to 20 parts by mass of the triazine-based ultraviolet absorber with respect to 100 parts by mass of the acrylic copolymer, thereby reducing the occurrence of acne skin and forming the pressure-sensitive adhesive layer Clouding can be prevented.

(Window film)
The window film of the present embodiment has a substrate and an adhesive layer provided on the substrate. The material of the substrate is not particularly limited, and, for example, polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyolefin resins such as polyethylene, polypropylene, poly 4-methylpentene-1 and polybutene-1; polycarbonate resins; Polyvinyl chloride resins; polyether sulfone resins; polyethylene sulfide resins; styrene resins; acrylic resins; polyamide resins; films made of cellulose resins such as cellulose acetate, etc., or laminated films of these.

  There is no restriction | limiting in particular in the thickness of a base material, Although it may select suitably according to the intended purpose, it is 5-200 micrometers, for example, is 10-100 micrometers, for example. The substrate may be transparent or colored, and for example, metals such as aluminum, gold, silver, copper, nickel, cobalt, chromium, tin and indium may be vapor-deposited.

  The base material may be surface-treated on one side or both sides by an oxidation method, a roughening method, or the like for the purpose of improving adhesion to a layer provided on the base material. Examples of the oxidation method include corona discharge treatment, chromic acid treatment (wet process), flame treatment, hot air treatment, ozone / ultraviolet radiation treatment and the like. Moreover, as a roughening method, the sandblasting method, the solvent treatment method, etc. are mentioned, for example.

  A release sheet may be provided on the pressure-sensitive adhesive layer of the window film for the purpose of protecting the pressure-sensitive adhesive layer and the like. Examples of the release sheet include those obtained by applying a release agent such as silicone resin to various plastic films such as polyethylene terephthalate and polypropylene. The thickness of the release sheet is not particularly limited, and is, for example, about 20 to 150 μm. In the case of using a window film, the release sheet may be peeled off and the pressure-sensitive adhesive layer may be attached in contact with the object. The composition of the pressure-sensitive adhesive layer of the window film will be described later.

The base may be provided with a hard coat layer on the side opposite to the pressure-sensitive adhesive layer.
The hard coat layer is obtained by applying a hard coat agent to the surface of the substrate opposite to the pressure-sensitive adhesive layer. As a hard coating agent, ultraviolet (UV) and electron beam curable coating materials, silicone hard coating agents, phosphazene resin hard coating agents, etc. can be used. Among the above hard coat agents, UV curable coatings can be used from the viewpoint of material cost, simplicity in the process of forming the hard coat layer, and the degree of freedom of composition. As the UV curable coating, those of vinyl polymerization type, polythiol / polyene type, epoxy type, amino alkyd type and the like can be used.

(Mappability)
For the measurement of the image clarity of a window film, the image clarity measurement apparatus based on JISK7374: 2007 can be used. As a specific image clarity measuring apparatus, for example, “ICM-1T” (trade name, manufactured by Suga Test Instruments Co., Ltd.) can be mentioned.

  The measurement of image clarity can be performed by using as a sample a window film which has a certain amount of time since production. For example, the image clarity may be measured using a window film sold at the store as a sample.

  Alternatively, in the case where the image clarity is measured as short as possible after the window film is manufactured, the window film subjected to the following treatment may be used as a sample.

  First, an adhesive layer is formed on one side of a resin film substrate to prepare a window film. As a method of forming a pressure-sensitive adhesive layer, for example, a method of directly applying a pressure-sensitive adhesive composition to a single surface of a substrate such as a resin film by a known method and removing a solvent by heating and the like to form a pressure-sensitive adhesive layer Can be mentioned. Alternatively, the pressure-sensitive adhesive composition is applied onto the release sheet by a known method, the solvent is removed to form a pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer is attached to one surface of a substrate such as a resin film. And the like. The thickness of the pressure-sensitive adhesive layer after solvent removal is, for example, 5 to 100 μm, and for example, 10 to 60 μm.

Subsequently, the obtained window film is placed in an environment in which the skin is more likely to be developed. Specifically, the window film is cut into an appropriate area (for example, 15 × 7 cm), and 30 sheets are stacked and sandwiched between two float glass plates within 3 hours after the window film is prepared. A load of 196 mN / cm ² is added to this, and it is allowed to stand in an environment of 70 ° C. for one week. This operation reproduces the step of storing the window film in a rolled state in the window film manufacturing process.

  Subsequently, it is allowed to stand at 23 ° C. and 50% relative humidity for one day or more, and the temperature and humidity are adjusted. Thereafter, the window film is taken out of the float glass plate, and used as a sample whose image clarity is to be measured.

The measurement of image clarity is performed as follows. First, if a release sheet is present on the pressure-sensitive adhesive layer of the window film, it is removed. Subsequently, the adhesive film of the window film is placed on the sample stand of the image clarity measuring apparatus with the pressure-sensitive adhesive layer facing the light source, and the image clarity is measured at a sample stand angle of 45 degrees, transmission mode, and 0.125 mm comb width. Specifically, the optical comb perpendicular to the ray axis of the transmitted light of the sample is moved, and the light amount (M) when the comb transmitting portion exists on the ray axis and the light shielding portion of the comb exist The light quantity (m) is determined, the ratio between the difference (M−m) and the sum (M + m) is calculated by the following equation (1), and the image clarity is calculated.
Mappability (%) = (M−m) / (M + m) × 100 (1)

  The closer the imageability value is to 100%, the clearer the image seen through the window film is with no distortion. In other words, it can be said that the generation of the eyelid is reduced as the value of the image clarity approaches 100%. The window film of the present embodiment has an image clarity of 80 to 100%. The image clarity may be, for example, 80 to 90%, or 85 to 90%.

(Adhesive force)
The measurement of the adhesive strength of the pressure-sensitive adhesive layer can be carried out on a window film which has had some time since its production. For example, the adhesion may be measured using a window film sold at the store as a sample. Alternatively, for example, a window film 14 days after production may be used as a sample.

  The adhesion of the pressure-sensitive adhesive layer is measured as follows. First, a window film of a sample is cut into a width of 25 mm and a length of 250 mm, and crimped to a float glass plate with one cycle of crimping using a 2 kg roller, under an environment of 23 ° C. and 50% relative humidity. Leave for a while, and adjust the temperature and humidity. Subsequently, using a tensile tester, the adhesion is measured under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 °.

  The window film of this embodiment may have an adhesion of 10 to 15 N / 25 mm as measured under the above conditions. The adhesive force may be, for example, 12 to 15 N / 25 mm, for example, 13 to 15 N / 25 mm. With this level of adhesion, it is practically sufficient as a window film.

(Characteristics of adhesive layer)
In one embodiment, the pressure-sensitive adhesive layer of the window film may contain an acrylic copolymer as a main component, and the acrylic copolymer has a carbon number of 4 to 4 having no crosslinkable functional group. The polymerizable monomer unit 5 may be contained in an amount of 10 to 70% by mass based on the solid content of the acrylic copolymer, and the storage elastic modulus at 70 ° C. of the pressure-sensitive adhesive layer may be 16 to 80 kPa. The acrylic copolymer may have a weight average molecular weight of 500,000 to 900,000. Such a window film is capable of reducing the occurrence of skin of the eyelid, preventing the whitening of the pressure-sensitive adhesive layer, and having sufficient adhesion.

(Pressure-sensitive adhesive layer and pressure-sensitive adhesive composition)
The pressure-sensitive adhesive layer of the window film of the present embodiment may contain an acrylic copolymer as a main component. When the pressure-sensitive adhesive layer contains an acrylic copolymer as a main component, it means that the pressure-sensitive adhesive layer contains, for example, 80% by mass or more, or 90% by mass or more of the acrylic copolymer. The pressure-sensitive adhesive layer is formed by applying the pressure-sensitive adhesive composition onto a substrate and removing the solvent by heating or the like. The pressure-sensitive adhesive composition may contain, in addition to the acrylic copolymer, a crosslinking agent, an ultraviolet light absorber, a solvent, and other components.

(Acrylic copolymer)
The above acrylic copolymer contains a methyl acrylate monomer unit in an amount of 1 to 20% by mass based on the solid content of the acrylic copolymer, and may contain 5 to 20% by mass; You may contain 20 mass%. By being more than a lower limit, suitable adhesive force can be provided and generation | occurrence | production of a skin can be prevented. However, when the methyl acrylate monomer unit is excessively contained in the acrylic copolymer, the triazine-based ultraviolet absorber used in the pressure-sensitive adhesive layer tends to be clouded due to steric hindrance, and by being below the above upper limit value, White turbidity of the pressure-sensitive adhesive layer can be prevented. The acrylic copolymer is a polymerizable monomer unit having 4 to 5 carbon atoms which does not have a crosslinkable functional group, a polymerizable monomer unit which has a carbon number other than 4 to 5 and does not have a crosslinkable functional group, Alternatively, it may contain a polymerizable monomer unit having a crosslinkable functional group, and means a copolymer in which at least one of the contained polymerizable monomer units is a (meth) acrylic acid alkyl ester monomer unit. Here, (meth) acrylic acid means acrylic acid or methacrylic acid. Moreover, "(meth) acrylic-acid alkylester monomer unit" means the repeating unit originating in the (meth) acrylic-acid alkylester monomer which comprises said acrylic copolymer. Similarly, the term "polymerizable monomer unit" means a repeating unit derived from the polymerizable monomer, which constitutes the above-mentioned acrylic copolymer. The carbon number of the polymerizable monomer unit having a carbon number other than 4 to 5 and having no crosslinkable functional group may be, for example, about 6 to 14 or so.

  Examples of the polymerizable monomer having a carbon number other than 4 to 5 and having no crosslinkable functional group include, for example, ethyl methacrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate and isobutyl (meth) Acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate and the like. These monomers may be used alone or in combination of two or more.

  Examples of the polymerizable monomer having a crosslinkable functional group include carboxyl group-containing monomers such as (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc. or anhydrides thereof (maleic anhydride etc. Hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, vinyl alcohol, allyl Hydroxyl group-containing monomers such as alcohols; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N -Hydro Amide-group-containing monomers such as sethyl acrylamide; amino-group-containing monomers such as aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate; glycidyl (meth) acrylate, methyl glycidyl Glycidyl group-containing monomers such as meta) acrylate; cyano group-containing monomers such as acrylonitrile and methacrylonitrile; N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole And heterocycle-containing vinyl monomers such as N-vinyloxazole; sulfonate group-containing monomers such as sodium vinyl sulfonate; phosphate group-containing monomers such as 2-hydroxyethyl acryloyl phosphate; Black hexyl maleimide, imide group-containing monomers such as isopropyl maleimide; 2-methacryloyl isocyanate group-containing monomers oxyethyl isocyanate, N- vinyl-2-pyrrolidone, and (meth) acryloyl morpholine. These monomers may be used alone or in combination of two or more.

  The acrylic copolymer may contain 10 to 70% by mass of a polymerizable monomer unit having 4 to 5 carbon atoms which does not have a crosslinkable functional group, based on the solid content of the acrylic copolymer. As a result, the pressure-sensitive adhesive layer can easily achieve both a high storage modulus and a good cohesion with good balance. As a result, it is possible to reduce the occurrence of acne skin and to obtain a window film having sufficient adhesion. The content of the polymerizable monomer unit having 4 to 5 carbon atoms which does not have a crosslinkable functional group may be, for example, 10 to 60% by mass based on the solid content of the acrylic copolymer, for example, 20 to 20%. 60 mass% may be sufficient.

  As a C4-5 polymerizable monomer unit which does not have a crosslinkable functional group, a methyl (meth) acrylate, an ethyl acrylate, vinyl acetate etc. are mentioned, for example. These monomers may be used alone or in combination of two or more.

  The weight average molecular weight of the acrylic copolymer may be, for example, 500,000 to 900,000, for example, 550,000 to 850,000, for example, 600,000 to 800,000. It is also good. When the weight average molecular weight of the acrylic copolymer is in this range, the pressure-sensitive adhesive layer can easily achieve both a high storage modulus and a good cohesion with good balance.

(UV absorber)
As the triazine-based ultraviolet absorber, known ultraviolet absorbers disclosed in Japanese Patent No. 5525183, Japanese Patent No. 5546706, etc. can be used, and for example, a compound represented by the following General Formula (A-1) May be

R ¹² , R ²² and R ³² are each independently a hydroxyl group, an alkyl group, an alkyloxy group or an alkyloxycarbonylalkyloxy group, and at least one of R ¹² , R ²² and R ³² is a hydroxyl group.
R ¹³ , R ²³ and R ^{33 each} independently represent a hydrogen atom or an alkyl group, and may be a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and may be a hydrogen atom or a methyl group, It may be a hydrogen atom.
R ¹⁴ , R ²⁴ and R ³⁴ independently represent a hydroxyl group, an alkyloxy group, an alkyl group, a hydroxyalkyloxy group, an alkyloxycarbonylalkyloxy group, a 3-alkyloxy-2-hydroxy-propyloxy group or an alkylcarbonyloxy It is a group.

  For example, Tinuvin 400, Tinuvin 405, Tinuvin 460, Tinuvin 477, Tinuvin 479 (all are trade names), etc. which are commercially available from BASF can be exemplified. Specifically, 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- Mono (hydroxyphenyl) triazine compounds such as triazine, 2- (2,4-dihydroxyphenyl) -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine; 2-hydroxy-4-propyloxyphenyl) -6- (2,4-dimethylphenyl) -1,3,5-triazine, 2,4-bis (2-hydroxy-3-methyl-4-propyloxy) Nyl) -6- (4-methylphenyl) -1,3,5-triazine, 2,4-bis (2-hydroxy-3-methyl-4-hexyloxyphenyl) -6- (2,4-dimethylphenyl) Bis (hydroxyphenyl) triazine compounds such as 1,)-1,3,5-triazine; 2,4-bis (2-hydroxy-4-butoxyphenyl) -6- (2,4-dibutoxyphenyl) -1,3 5,5-Triazine, 2,4,6-tris (2-hydroxy-4-octyloxyphenyl) -1,3,5-triazine, 2,4,6-tris [2-hydroxy-4- (3-butoxy) And tris (hydroxyphenyl) triazine compounds such as -2-hydroxypropyloxy) phenyl] -1,3,5-triazine and the like.

  In addition, for the purpose of preventing flying insect attraction, use of a hydroxyphenyltriazine-based ultraviolet absorber (for example, Tinuvin 460, Tinuvin 477 (all are trade names), etc.) for blocking ultraviolet rays of relatively long wavelength of about 300 to 400 nm. Can.

  The content of the triazine-based ultraviolet absorber is 10 to 20 parts by mass, may be 12 to 19 parts by mass, or 14 to 18 parts by mass with respect to 100 parts by mass of the acrylic copolymer. It is also good.

  As a UV absorber, in the pressure-sensitive adhesive layer, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-) 3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3'-tert-amyl-5'-isobutylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3′-isobutyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-3′-isobutyl-5′-propylphenyl) -5-chlorobenzotriazole, etc. 2'-hydroxyphenyl-5-chlorobenzotriazole ultraviolet absorbers of the following; 2- (2'-hydroxy-3 ', 5'-di-tert- 2'-hydroxyphenylbenzotriazole ultraviolet absorbers such as tylphenyl) benzotriazole, 2- (2'-hydroxy-5'-methylphenyl) benzotriazole; 2,2'-dihydroxy-4-methoxybenzophenone, 2,2 2,2'-dihydroxybenzophenone-based ultraviolet absorbers such as '-dihydroxy-4,4'-dimethoxybenzophenone and 2,2', 4,4'-tetrahydroxybenzophenone; 2-hydroxy-4-methoxybenzophenone, 2, 2-hydroxybenzophenone type ultraviolet absorbers such as 4-dihydroxybenzophenone; salicylic acid ester type ultraviolet absorbers such as phenyl salicylate, 4-tert-butyl-phenyl-salicylate; 2-ethyl-hexyl-2-cyano-3, 3- Diphenyl Acry Cyanoacrylate based ultraviolet light absorbers such as ethyl, 2-cyano-3, 3-diphenylacrylate, octyl-2-cyano-3, 3-diphenylacrylate; reactions in which an acryloyl group or methacryloyl group is introduced into the benzotriazole skeleton It may have a UV absorber or the like.

(Crosslinking agent)
The crosslinking agent is a compound which crosslinks the crosslinkable functional groups contained in the above-mentioned acrylic copolymer. As a crosslinking agent, an isocyanate type crosslinking agent, an epoxy type crosslinking agent, an aziridine type crosslinking agent, a chelate type crosslinking agent etc. are mentioned. As an isocyanate type crosslinking agent, tolylene diisocyanate (TDI), hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), hydrogenated tolylene diisocyanate, diphenylmethane diisocyanate, trimethylolpropane modified TDI, etc. It can be mentioned. Examples of the epoxy crosslinking agent include ethylene glycol glycidyl ether, 1,6-hexanediol glycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like. As an aziridine type crosslinking agent, 2,2-bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate], 4,4-bis (ethyleneiminocarboxyamino) diphenylmethane, tris-2,4,6- ( Examples include 1-aziridinyl) -1,3,5-triazine, tris [1- (2-methyl) aziridinyl] phosphinic oxide, hexa [1- (2-methyl) -aziridinyl] triphosphatriazine and the like. As a chelate type crosslinking agent, aluminum chelate, titanium chelate, etc. are mentioned.

  The crosslinking agent may be used alone or in combination of two or more. The amount of the crosslinking agent used is, for example, 0.01 to 10 parts by mass, for example, 0.05 to 5 parts by mass, with respect to 100 parts by mass of the solid content in the pressure-sensitive adhesive composition. By appropriately adjusting the amount of the crosslinking agent, it is possible to develop the adhesion properties necessary for various adherends.

(solvent)
As a solvent for dissolving or dispersing the material of the pressure-sensitive adhesive composition, for example, aliphatic hydrocarbons such as hexane, heptane and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, Alcohols such as methanol, ethanol, propanol and butanol; ketones such as acetone, methyl ethyl ketone, 2-pentanone and isophorone; esters such as ethyl acetate and butyl acetate; and cellosolve solvents such as ethyl cellosolve.

  The concentration and viscosity of the pressure-sensitive adhesive composition may be any concentration and viscosity that can be coated, and are not particularly limited, and can be appropriately adjusted depending on the situation.

(Other ingredients)
Other components include, for example, fillers such as organic powders or inorganic powders; plasticizers such as aromatic esters and chlorinated paraffins; retarders such as acetylacetone; antioxidants; colorants; antistatic agents, etc. It can be mentioned. These may be used alone or in combination of two or more.

(Storage elastic modulus)
Although not bound by theory, the inventors speculate that it is effective for the pressure-sensitive adhesive layer of the window film to have a certain degree of hardness in order to reduce the occurrence of acne skin. More specifically, when the storage elastic modulus at 70 ° C. of the pressure-sensitive adhesive layer is 16 to 80 kPa, the development of a sore skin tends to be reduced. The storage elastic modulus at 70 ° C. of the pressure-sensitive adhesive layer may be, for example, 20 to 80 kPa, and may be, for example, 30 to 75 kPa.

  The storage elastic modulus is measured by a torsional shear method in an environment of 1 Hz and 70 ° C. using a viscoelasticity measuring device. The sample size of the pressure-sensitive adhesive layer whose storage elastic modulus is to be measured is 8 mm in diameter × 3 mm in thickness.

(Method of manufacturing window film)
The window film of the present embodiment can be manufactured, for example, as follows. First, the pressure-sensitive adhesive composition described above is applied on the above-described base material to a suitable thickness by a known coating apparatus. Examples of the coating apparatus include a roll coater, a knife coater, a roll knife coater, a fountain die coater, a slot die coater, a reverse coater and the like. Then, the solvent in an adhesive composition is removed by heating at the temperature of about 80-150 degreeC, and the crosslinkable functional group of each component in an adhesive composition is bridge | crosslinked. A release sheet may be attached on the pressure-sensitive adhesive layer to protect the pressure-sensitive adhesive layer. Alternatively, the window film may be produced by a method in which the pressure-sensitive adhesive layer is formed on a release sheet and subsequently transferred onto a substrate.

  EXAMPLES The present invention will next be described in more detail by way of examples, which should not be construed as limiting the invention thereto.

[Production of acrylic copolymer]
The acrylic monomers shown in Table 1 were mixed and polymerized in the proportion (% by mass) shown in Table 1 to produce acrylic copolymers of Production Examples 1 to 6. The weight average molecular weight of the acrylic copolymer of each production example was measured by gel permeation chromatography (GPC), and the results are shown in Table 1 in terms of standard polystyrene equivalent. The meanings of the abbreviations in Table 1 are as follows.
BA: butyl acrylate 2 EHA: 2-ethylhexyl acrylate EA: ethyl acrylate MA: methyl acrylate AAc: acrylic acid 4HBA: 4-hydroxybutyl acrylate VAc: vinyl acetate

Example 1
The components shown in Table 2 were mixed with 100 parts by mass of the acrylic polymer of Production Example 4 in the proportions shown in Table 2 and stirred to obtain a homogeneous pressure-sensitive adhesive composition. In Table 2, the compounding quantity of methyl ethyl ketone is a mass part in a liquid state. Moreover, about components other than methyl ethyl ketone, it is the mass part of solid content conversion. Tinuvin 477 (hydroxyphenyl triazine-based ultraviolet absorber manufactured by BASF Corporation) was used as the triazine-based ultraviolet absorber. Coronate HL (made by Tosoh Corporation) was used as an isocyanate type crosslinking agent.

  The above pressure-sensitive adhesive composition was cast using a knife coater on the release surface of a polyethylene terephthalate film (release sheet) coated with a silicone release agent. Subsequently, the solvent was removed by heating at 90 ° C. for 1 minute to form a pressure-sensitive adhesive layer with a thickness of 10 μm. Subsequently, the formed pressure-sensitive adhesive layer was attached to a polyethylene terephthalate film (trade name "Lumirror T60", thickness 50 μm, manufactured by Toray Industries, Inc.) to obtain a window film of Example 1.

Example 2, Reference Examples 1 to 3, Comparative Example 1
Example 1 except using the acrylic polymer of Production Examples 1 to 3 and 5 to 6 instead of the acrylic polymer of Production Example 4 and mixing the components shown in Table 2 in the ratio shown in Table 2 The window films of Example 2, Reference Examples 1 to 3 and Comparative Example 1 were obtained in the same manner as in the above.

[Measurement of turbidity]
5 ml of the pressure-sensitive adhesive solution used in Examples 1 to 2 and Reference Examples 1 to 3 and Comparative Example 1 is placed in a glass bottle (bore diameter x body diameter x height: 14.5 mm x 27 mm x 55 mm, volume 20 ml), The solution was stored in a thermostat at 80.degree. C. for 24 hours to volatilize the solvent in the pressure-sensitive adhesive solution, and then removed under a room temperature environment of 23.degree. After adjusting the temperature for 24 hours under the same environment, the transparency of the pressure-sensitive adhesive was evaluated visually.
Those with white turbidity and no visibility over the pressure-sensitive adhesive were evaluated as ×, those with white turbidity but with slight visibility over the pressure-sensitive adhesive were marked Δ, and those with no white turbidity were rated as ○ did. By reducing the methyl acrylate monomer unit to 20% by mass or less based on the solid content of the acrylic copolymer, it was possible to prevent white turbidity.

[Measurement of mappability]
The window films of Examples 1 to 2 and Reference Examples 1 to 3 and Comparative Example 1 are cut into 15 × 7 cm, and 30 sheets are laminated within 3 hours after preparation of the window film and sandwiched between two float glass plates. It is. A load of 196 mN / cm ² was added to this, and it was allowed to stand for one week in an environment of 70 ° C. Then, it was left to stand at 23 ° C. and 50% relative humidity for one day or more, and was subjected to temperature and humidity control. Thereafter, the window film was taken out from the float glass plate and used as a sample whose image clarity was to be measured.

  The image clarity was measured using the image clarity measurement device “ICM-1T” (trade name, manufactured by Suga Test Instruments Co., Ltd.), with the adhesive layer of the window film directed to the light source. The sample was placed on a table, and the image clarity was measured at a sample table angle of 45 degrees, a transmission mode, and a comb width of 0.125 mm.

  The results are shown in Table 3. The window films of Examples 1 to 2 and Reference Examples 1 to 3 were able to achieve 80% image clarity.

[Measurement of adhesive strength]
The adhesive force was measured by using as a sample the window film of Example 1-2, the reference examples 1-3, and the comparative example 1 14 days after manufacture. First, each window film was cut into a width of 25 mm and a length of 250 mm. Then, each window film was crimped | bonded to the float glass board by 1 reciprocation 1 reciprocation using a 2 kg roller. Subsequently, it was left for 24 hours in an environment of 23 ° C. and 50% relative humidity. Subsequently, using a tensile tester (trade name "Tensilon" manufactured by Orientec Co., Ltd.), the adhesive strength was measured under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 °.

  The results are shown in Table 3. The window films of Examples 1 to 2 and Reference Examples 1 to 3 were able to achieve an adhesive strength of 10 N / 25 mm.

[Measurement of storage modulus]
The pressure-sensitive adhesive layers of the window films of Examples 1 to 2 and Reference Examples 1 to 3 and Comparative Example 1 were laminated to obtain a sample having a size of 8 mm in diameter and 3 mm in thickness. The storage elastic modulus of each of these samples was measured by a torsional shear method under an environment of 1 Hz and 70 ° C. using a viscoelasticity measuring apparatus (manufactured by Anton Paar, apparatus name “MCR 300”).

  The results are shown in Table 3. The pressure-sensitive adhesive layer of the window film of each of Examples 1 to 2 and Reference Examples 1 to 3 in which the occurrence of the acne skin was reduced had a storage elastic modulus at 70 ° C. in the range of 16 to 80 kPa.

  According to the present invention, it is possible to provide a window film which can reduce the occurrence of acne skin, can prevent whitening of the pressure-sensitive adhesive layer, and has an excellent ultraviolet absorbing performance. In addition, it is expected to prevent deterioration of the substrate film due to ultraviolet light, prevent deterioration of the adhesive itself, and prevent color fading by having excellent ultraviolet light absorption performance, and for the purpose of ultraviolet light cutting in sunlight and preventing flying insects attraction. It can be expected to be used as a window film.

Claims (5)

A window film comprising a substrate and an adhesive layer provided on the substrate, the window film comprising
The pressure-sensitive adhesive layer contains an acrylic copolymer and a triazine ultraviolet absorber.
The acrylic copolymer contains 1 to 20% by mass of a methyl acrylate monomer unit based on the solid content of the acrylic copolymer,
The pressure-sensitive adhesive layer contains the triazine-based ultraviolet absorber in an amount of 10 to 20 parts by mass with respect to 100 parts by mass of the acrylic copolymer.
Using an image clarity measuring device in accordance with JIS K 7374: 2007, install the window film with the adhesive layer facing the light source on the sample table, and set the sample table angle 45 degrees, transmission mode, comb width 0.125 mm Window film whose measured image clarity is 80 to 100%. The window film of Claim 1 in which the said triazine type ultraviolet absorber is represented with the following general formula (A-1).

R ¹² , R ²² and R ³² are each independently a hydroxyl group, an alkyl group, an alkyloxy group or an alkyloxycarbonylalkyloxy group, and at least one of R ¹² , R ²² and R ³² is a hydroxyl group.
R ¹³ , R ²³ and R ^{33 each} independently represent a hydrogen atom or an alkyl group, and may be a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, and may be a hydrogen atom or a methyl group, It may be a hydrogen atom.
R ¹⁴ , R ²⁴ and R ³⁴ independently represent a hydroxyl group, an alkyloxy group, an alkyl group, a hydroxyalkyloxy group, an alkyloxycarbonylalkyloxy group, a 3-alkyloxy-2-hydroxy-propyloxy group or an alkylcarbonyloxy It is a group. The pressure-sensitive adhesive layer contains the acrylic copolymer as a main component, and the acrylic copolymer includes the polymerizable monomer unit having 4 to 5 carbon atoms which does not have a crosslinkable functional group, and the acrylic copolymer. 10 to 70% by mass based on the solid content of the polymer,
The window film of Claim 1 or 2 whose storage elastic modulus at 70 degrees C of the said adhesive layer is 16-80 kPa.   A window film cut into a width of 25 mm is crimped to a float glass plate by one reciprocation using a 2 kg roller, and after leaving for 24 hours under an environment of 23 ° C. and a relative humidity of 50%, the peeling speed of 300 mm / min. The window film according to any one of claims 1 to 3, wherein the adhesion measured at a peeling angle of 180 ° is 10 to 15 N / 25 mm.   The window film according to any one of claims 1 to 4, wherein the weight average molecular weight of the acrylic copolymer is 500,000 to 900,000.