JP6387563B2 - Screen protection film - Google Patents

Description

  The present invention relates to a screen protection film.

  Screen protection film is used for display screens of personal computers, personal digital assistants, flat panel displays, etc. for the purpose of dust prevention, scratch prevention, fingerprint prevention, peep prevention, glass scattering prevention, reflection prevention, blue light cut, decoration, etc. It is an adhesive film to be affixed and is widely used.

  By the way, the image seen through the screen protective film in a state of being pasted on the display screen may not be clear, and may look like a yuzu skin (mottled). This phenomenon is caused by the occurrence of irregularities on the surface of the pressure-sensitive adhesive layer of the screen protective film. A screen protection film that generates a yuzu skin may have a poor appearance, leading to a reduction in the appeal of the product in the market.

  As one of the causes of unevenness on the surface of the pressure-sensitive adhesive layer of the screen protective film, it is considered that the separation force of the separation material with respect to the pressure-sensitive adhesive layer is too high. For example, Patent Document 1 proposes a pressure-sensitive adhesive film in which the separation force of the separation material from the pressure-sensitive adhesive layer is 1.0 to 10.0 gf / 25 mm as a protective film for preventing the generation of itchy skin. Yes.

Japanese Patent Laid-Open No. 11-80684

  In the process of storing the screen protective film in a roll shape among the manufacturing processes of the screen protective film, the inventors have applied the screen by the pressure applied to the core of the roll of the screen protective film wound in a roll shape. It has been found that the pressure-sensitive adhesive layer of the protective film is deformed and the skin is generated.

  In addition, the inventors of the present invention have a screen protection film in which the occurrence of itchy skin is reduced, and the screen protection film in which the occurrence of itchy skin is reduced. It has been found that the content of methyl acrylate monomer units in the acrylic copolymer of the pressure-sensitive adhesive layer tends to be insufficient.

In order to impart excellent ultraviolet absorption performance and blue light cut performance, it is conceivable to use a triazine-based ultraviolet absorber in the pressure-sensitive adhesive layer.
Furthermore, the inventors include a triazine-based UV absorber in the pressure-sensitive adhesive layer for the purpose of imparting excellent UV absorption performance and blue light cut performance in the screen protection film in which the generation of the yuzu skin is reduced. As a result of the experiment, it was found that some of the pressure-sensitive adhesive layer were likely to be clouded and some were not.

  Therefore, an object of the present invention is to provide a screen protective film in which the occurrence of itchy skin is reduced, the cloudiness of the pressure-sensitive adhesive layer can be prevented, and the ultraviolet light absorbing performance is imparted to the pressure-sensitive adhesive layer.

The present invention is as follows.
(1) A screen protection film having a base material and a pressure-sensitive adhesive layer provided on the base material,
The base material is provided with a hard coat layer on the surface opposite to the pressure-sensitive adhesive layer,
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 10 to 20 parts by mass of the triazine-based ultraviolet absorber with respect to 100 parts by mass of the acrylic copolymer.
Using an image clarity measuring device in accordance with JIS K7374: 2007, the screen protective film adhesive layer is placed on the sample stage with the light source facing the light source, and the sample stage angle is 45 degrees, the transmission mode, and the comb width is 0.125 mm. A screen protective film having a measured image clarity of 80 to 100%.
(2) The screen protective film according to (1), wherein the triazine-based ultraviolet absorber is represented by the following general formula (A-1).

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。

R ¹² , R ²² and R ³² are 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 are independently a hydrogen atom or an alkyl group, and may be a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, or may be a hydrogen atom or a methyl group, It may be a hydrogen atom.
R ¹⁴ , R ²⁴ and R ³⁴ are independently hydroxyl, alkyloxy, alkyl, hydroxyalkyloxy, alkyloxycarbonylalkyloxy, 3-alkyloxy-2-hydroxy-propyloxy or alkylcarbonyloxy. It is a group.

(3) The pressure-sensitive adhesive layer contains an acrylic copolymer as a main component, and the acrylic copolymer contains a polymerizable monomer unit having 4 to 5 carbon atoms that does not have a crosslinkable functional group. 10 to 70% by mass based on the solid content of the copolymer,
The screen protective film as described in (1) or (2) whose storage elastic modulus in 70 degreeC of the said adhesive layer is 16-80 kPa.
(4) The screen protective film according to any one of (1) to (3), wherein the acrylic copolymer has a weight average molecular weight of 500,000 to 900,000.
(5) The screen protective film according to any one of (1) to (4), wherein a supporting base material and a silicone-based pressure-sensitive adhesive layer are laminated in this order on the pressure-sensitive adhesive layer.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the yuzu skin can be reduced, the cloudiness of an adhesive layer can be prevented, and the screen protection film which has the outstanding ultraviolet-ray absorption performance can be provided.

  In one embodiment, the present invention is a screen protection film having a base material and a pressure-sensitive adhesive layer provided on the base material, wherein the pressure-sensitive adhesive layer comprises an acrylic copolymer and a triazine-based ultraviolet absorber. The acrylic copolymer contains 1-20% by mass of a methyl acrylate monomer unit based on the solid content of the acrylic copolymer, and the pressure-sensitive adhesive layer absorbs the triazine ultraviolet ray. An agent is contained 10 to 20 parts by mass with respect to 100 parts by mass of the acrylic copolymer.

  In order to prevent the generation of itchy skin, it is necessary that the acrylic copolymer used for the pressure-sensitive adhesive layer contains a lot of methyl acrylate monomer units having a relatively high polarity. However, if the acrylic copolymer contains an excessive amount of methyl acrylate monomer units, it tends to become cloudy due to the steric hindrance of the triazine-based ultraviolet absorber used in the pressure-sensitive adhesive layer. In the screen protective film of the present invention in which the ultraviolet ray absorbing performance is imparted to the pressure-sensitive adhesive layer, the acrylic copolymer contains 1 to 20% by mass of a methyl acrylate monomer unit based on the solid content of the acrylic copolymer. And 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 itchy skin and the pressure-sensitive adhesive layer. Can be prevented.

(Screen protection film)
The screen protection film of this embodiment has a base material and an adhesive layer provided on the base material. There is no restriction | limiting in particular in the material of a base material, For example, Polyester-type resin, such as a polyethylene terephthalate and a polyethylene naphthalate; Polyolefin-type resin, such as polyethylene, a polypropylene, poly 4-methylpentene-1, polybutene-1, and polycarbonate-type resin; Examples thereof include a polyvinyl chloride resin; a polyether sulfone resin; a polyethylene sulfide resin; a styrene resin; an acrylic resin; a polyamide resin; a film made of a cellulose resin such as cellulose acetate, or a laminated film thereof.

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

  The base material may be subjected to a surface treatment on one or both sides by an oxidation method, a concavo-convex method, or the like for the purpose of improving adhesion with a layer provided on the base material. Examples of the oxidation method include corona discharge treatment, chromic acid treatment (wet), flame treatment, hot air treatment, ozone / ultraviolet irradiation treatment, and the like. Examples of the unevenness method include a sand blast method and a solvent treatment method.

  A release sheet may be provided on the adhesive layer of the screen protective film for the purpose of protecting the adhesive layer. Examples of the release sheet include those obtained by applying a release agent such as silicone to various plastic films such as polyethylene terephthalate and polypropylene. Although there is no restriction | limiting in particular in the thickness of a peeling sheet, For example, it is about 20-150 micrometers. When using a screen protection film, the release sheet may be peeled off and attached so that the adhesive layer is in contact with the object. The configuration of the adhesive layer of the screen protection film will be described later.

The base material is provided with a hard coat layer on the surface opposite to the pressure-sensitive adhesive layer.
A hard-coat layer is obtained by apply | coating a hard-coat agent to the surface on the opposite side to the adhesive layer of a base material. As the hard coating agent, a resin curable by ultraviolet rays, electron beams or heat can be used. Examples of the resin that is cured by ultraviolet rays or electron beams include polyfunctional (meth) acrylate oligomers such as a polyfunctional acrylate monomer, polyester acrylate, epoxy acrylate, urethane acrylate, and polyol acrylate. Examples of the resin that is cured by heat include silicone. Among the above hard coat agents, UV curable paints can be used from the viewpoints of material cost, simplicity in the process of forming the hard coat layer, and the degree of freedom of composition.

In order to attach the screen protection film to the screen without forming bubbles at the interface between the film and the screen, the acrylic adhesive layer is not directly attached to the screen, but the supporting base material is attached to the acrylic adhesive layer. A silicone-based pressure-sensitive adhesive layer may be laminated via
As the support substrate, the same substrate as that described above can be used.
The silicone-based pressure-sensitive adhesive can be obtained by adding an organohydrogenpolysiloxane as a crosslinking agent to a vinyl group-containing organopolysiloxane as a main agent and a platinum-based catalyst as a catalyst to cause an addition reaction. Moreover, you may add a silicone resin as a tackifier.

(Image clarity)
For the measurement of the image clarity of the screen protective film, a image clarity measuring device based on JIS K7374: 2007 can be used. Specific examples of the image clarity measuring apparatus include “ICM-1T” (trade name, manufactured by Suga Test Instruments Co., Ltd.).

  The image clarity can be measured using a screen protection film after a certain amount of time has passed since manufacture as a sample. For example, the image clarity may be measured using a screen protective film sold at a store as a sample.

  Or when measuring image clarity in the shortest possible time after manufacture of a screen protection film, it is good also considering the screen protection film which performed the following processes as a sample.

  First, a pressure-sensitive adhesive layer is formed on one side of a resin film substrate to produce a screen protection film. As a method of forming the pressure-sensitive adhesive layer, for example, a method of directly forming the pressure-sensitive adhesive composition on one side of a substrate such as a resin film by a known method, and removing the solvent by heat drying or the like to form the pressure-sensitive adhesive layer Is mentioned. Alternatively, a pressure-sensitive adhesive composition is applied onto a release sheet by a known method, and after removing the solvent to form a pressure-sensitive adhesive layer, this is adhered to one side of a substrate such as a resin film, and the pressure-sensitive adhesive layer And a method of transferring the above. The thickness of the pressure-sensitive adhesive layer after removing the solvent is, for example, 5 to 100 μm, for example, 10 to 60 μm.

Subsequently, the obtained screen protection film is placed in an environment in which it is easier for the yuzu skin to occur. Specifically, the screen protective film is cut into an appropriate area (for example, 15 × 7 cm), and 30 sheets are laminated and sandwiched between two float glass plates within 3 hours after the production of the screen protective film. A load of 196 mN / cm ² is applied thereto, and the mixture is allowed to stand in a 70 ° C. environment for 1 week. This operation reproduces the process of storing the screen protection film in a rolled state in the screen protection film manufacturing process.

  Subsequently, the sample is left to stand for 1 day or more in a 23 ° C., 50% relative humidity environment to adjust the humidity. Thereafter, the screen protection film is taken out of the float glass plate and used as a sample for measuring image clarity.

The image clarity is measured as follows. First, when a release sheet exists on the pressure-sensitive adhesive layer of the screen protective film, it is peeled off. Subsequently, the adhesive layer of the screen protective film is placed on the sample stage of the image clarity measuring device with the light source facing the light source, and the image clarity is measured at a sample stage angle of 45 degrees, a transmission mode, and a comb width of 0.125 mm. Specifically, the optical comb perpendicular to the beam axis of the transmitted light of the sample is moved so that the amount of light (M) when the comb transmission portion exists on the beam axis and the light shielding portion of the comb exists. The light quantity (m) is obtained, and the ratio between the difference (M−m) and the sum (M + m) is calculated by the following equation (1) to calculate the image clarity.
Image clarity (%) = (M−m) / (M + m) × 100 (1)

  The closer the image clarity value is to 100%, the clearer the image viewed through the screen protection film is. In other words, it can be said that the closer the value of the image clarity is to 100%, the more the generation of the yuzu skin is reduced. The screen protection film of this embodiment has a image clarity of 80 to 100%. The image clarity may be, for example, 80 to 90% or 85 to 90%.

(Characteristics of adhesive layer)
In one embodiment, the pressure-sensitive adhesive layer of the screen protection film may contain an acrylic copolymer as a main component, and the acrylic copolymer has 4 carbon atoms having no crosslinkable functional group. It may contain 10 to 70% by mass of ˜5 polymerizable monomer units 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 screen protection film can reduce the occurrence of yuzu skin and prevent white turbidity of the pressure-sensitive adhesive layer.

(Adhesive layer and adhesive composition)
The adhesive layer of the screen protective film of this embodiment may contain an acrylic copolymer as a main component. That the pressure-sensitive adhesive layer is mainly composed of an acrylic copolymer 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 a pressure-sensitive adhesive composition on a substrate and removing the solvent by heating or the like. The pressure-sensitive adhesive composition may contain a crosslinking agent, an ultraviolet absorber, a solvent, and other components in addition to the acrylic copolymer.

(Acrylic copolymer)
Said acrylic copolymer contains 1-20 mass% of methyl acrylate monomer units on the basis of the solid content of the acrylic copolymer, and may contain 5-20 mass%. You may contain 20 mass%. By being more than a lower limit, generation | occurrence | production of the yuzu skin can be prevented. However, when the methyl acrylate monomer unit is excessively contained in the acrylic copolymer, it tends to become cloudy from the steric hindrance of the triazine-based ultraviolet absorber used in the pressure-sensitive adhesive layer. The cloudiness of the pressure-sensitive adhesive layer can be prevented. The acrylic copolymer is a polymerizable monomer unit having 4 to 5 carbon atoms that does not have a crosslinkable functional group, a polymerizable monomer unit that has a carbon number other than 4 to 5 and does not have a crosslinkable functional group, Alternatively, it may include a polymerizable monomer unit having a crosslinkable functional group, and means a copolymer in which at least one of the polymerizable monomer units contained is a (meth) acrylic acid alkyl ester monomer unit. Here, (meth) acrylic acid means acrylic acid or methacrylic acid. The “(meth) acrylic acid alkyl ester monomer unit” means a repeating unit derived from the (meth) acrylic acid alkyl ester monomer, which constitutes the acrylic copolymer. Similarly, the “polymerizable monomer unit” means a repeating unit derived from a polymerizable monomer that constitutes the above acrylic copolymer. The number of carbon atoms of the polymerizable monomer unit having a carbon number other than 4 to 5 and having no crosslinkable functional group may be about 6 to 14, for example.

  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). Examples include acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and lauryl (meth) acrylate. These monomers may be used alone or in combination of two or more.

  As a polymerizable monomer having a crosslinkable functional group, a carboxyl group-containing monomer such as (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid, or an anhydride thereof (such as maleic anhydride); 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, hydroxyalkyl (meth) acrylates such as 6-hydroxyhexyl (meth) acrylate, vinyl alcohol, allyl alcohol, etc. Hydroxyl group-containing monomers: (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-hydride Amide group-containing monomers such as xylethylacrylamide; amino group-containing monomers such as aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate; glycidyl (meth) acrylate, methylglycidyl ( Glycidyl group-containing monomers such as (meth) acrylate; Cyano group-containing monomers such as acrylonitrile and methacrylonitrile; N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrrole, N-vinylimidazole Heterocycle-containing vinyl monomers such as N-vinyl oxazole; sulfonic acid group-containing monomers such as sodium vinyl sulfonate; and phosphate group-containing monomers such as 2-hydroxyethylacryloyl phosphate Cyclohexyl 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 that does not have a crosslinkable functional group, based on the solid content of the acrylic copolymer. Thereby, an adhesive layer becomes a high storage elastic modulus. As a result, it is possible to obtain a screen protection film with reduced generation of yuzu skin. The content of the polymerizable monomer unit having 4 to 5 carbon atoms not having 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%. It may be 60% by mass.

  As a C4-C5 polymerizable monomer unit which does not have a crosslinkable functional group, methyl (meth) acrylate, 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, Also good. When the weight average molecular weight of the acrylic copolymer is within this range, the pressure-sensitive adhesive layer has a high storage elastic modulus.

(UV absorber)
As the triazine-based ultraviolet absorber, a known ultraviolet absorber disclosed in Japanese Patent No. 5525183, Japanese Patent No. 5546706 and the like can be used, and for example, it is a compound represented by the following general formula (A-1). May be.

R ¹² , R ²² and R ³² are 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. It is preferable that at least two of them are hydroxyl groups in that blue light having a longer wavelength than ultraviolet rays can be cut.
R ¹³ , R ²³ and R ³³ are independently a hydrogen atom or an alkyl group, and may be a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, or may be a hydrogen atom or a methyl group, It may be a hydrogen atom.
R ¹⁴ , R ²⁴ and R ³⁴ are independently hydroxyl, alkyloxy, alkyl, hydroxyalkyloxy, alkyloxycarbonylalkyloxy, 3-alkyloxy-2-hydroxy-propyloxy or alkylcarbonyloxy. It is a group.

  For example, Tinuvin 400, Tinuvin 405, Tinuvin 460, Tinuvin 477, and Tinuvin 479 (all are trade names) etc. which are marketed from BASF can be illustrated. 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; 2,4-bis ( 2-hydroxy-4-propyloxyphenyl) -6- (2,4-dimethylphenyl) -1,3,5-triazine, 2,4-bis (2-hydroxy-3-methyl-4-propyloxyph) Nyl) -6- (4-methylphenyl) -1,3,5-triazine, 2,4-bis (2-hydroxy-3-methyl-4-hexyloxyphenyl) -6- (2,4-dimethylphenyl) ) -1,3,5-triazine and other bis (hydroxyphenyl) triazine compounds; 2,4-bis (2-hydroxy-4-butoxyphenyl) -6- (2,4-dibutoxyphenyl) -1,3 , 5-triazine, 2,4,6-tris (2-hydroxy-4-octyloxyphenyl) -1,3,5-triazine, 2,4,6-tris [2-hydroxy-4- (3-butoxy And 2-tris (hydroxyphenyl) triazine compounds such as 2-hydroxypropyloxy) phenyl] -1,3,5-triazine.

  Further, a bis (hydroxyphenyl) triazine compound or a tris (hydroxyphenyl) triazine compound is preferable in that it can cut blue light (380 to 495 nm) having a longer wavelength than ultraviolet light (300 to 380 nm). Examples of product names include tinuvin 460 and tinuvin 477.

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

  In addition to the UV absorber, the pressure-sensitive adhesive layer includes 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; 2- (2'-hydroxy-3 ', 5'-di-tert- 2'-hydroxyphenylbenzotriazole-based UV absorbers such as 2- (2'-hydroxy-5'-methylphenyl) benzotriazole; 2,2'-dihydroxy-4-methoxybenzophenone, 2,2 2,2′-dihydroxybenzophenone ultraviolet absorbers such as “-dihydroxy-4,4′-dimethoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone; 2-hydroxy-4-methoxybenzophenone, 2, 2-hydroxybenzophenone ultraviolet absorbers such as 4-dihydroxybenzophenone; salicylic acid ester ultraviolet absorbers such as phenyl salicylate and 4-tert-butyl-phenyl-salicylate; 2-ethyl-hexyl-2-cyano-3,3- Diphenyl acrylic Cyanoacrylate UV absorbers such as ethyl 2-cyano-3,3-diphenyl acrylate, octyl-2-cyano-3,3-diphenyl acrylate; reaction in which acryloyl group or methacryloyl group is introduced into benzotriazole skeleton Type ultraviolet absorbers and the like.

(Crosslinking agent)
A crosslinking agent is a compound which bridge | crosslinks the crosslinkable functional groups contained in said acrylic copolymer. Examples of the crosslinking agent include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, aziridine-based crosslinking agents, and chelate-based crosslinking agents. Isocyanate-based crosslinking agents include tolylene diisocyanate (TDI), hexamethylene diisocyanate (HMDI), isophorone diisocyanate (IPDI), xylylene diisocyanate (XDI), hydrogenated tolylene diisocyanate, diphenylmethane diisocyanate, trimethylolpropane modified TDI, and the like. 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. Examples of the aziridine-based crosslinking agent include 2,2-bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate], 4,4-bis (ethyleneiminocarboxyamino) diphenylmethane, tris-2,4,6- ( 1-aziridinyl) -1,3,5-triazine, tris [1- (2-methyl) aziridinyl] phosphine oxide, hexa [1- (2-methyl) -aziridinyl] triphosphatriazine and the like. Examples of chelate crosslinking agents include aluminum chelates and titanium chelates.

  A crosslinking agent may be used independently and may use 2 or more types together. The usage-amount of a crosslinking agent is 0.01-10 mass parts with respect to 100 mass parts of solid content in an adhesive composition, for example, is 0.05-5 mass parts. By appropriately adjusting the amount of the crosslinking agent, it is possible to develop the necessary adhesive properties for various adherends.

(solvent)
Examples of the solvent for dissolving or dispersing the material of the pressure-sensitive adhesive composition include aliphatic hydrocarbons such as hexane, heptane and cyclohexane, aromatic hydrocarbons such as toluene and xylene, halogenated hydrocarbons such as methylene chloride and ethylene chloride, Examples thereof include 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 density | concentration and viscosity of an adhesive composition should just be the density | concentration and viscosity which can be coated, and it does not restrict | limit in particular, It can adjust suitably according to a condition.

(Other ingredients)
Examples of other components include fillers such as organic powders or inorganic powders; plasticizers such as aromatic esters and chlorinated paraffins; retarders such as acetylacetone; antioxidants; colorants; Can be mentioned. These may be used alone or in combination of two or more.

(Storage modulus)
Although not bound by theory, the inventors speculate that it is effective to have a certain degree of hardness in the adhesive layer of the screen protection film in order to reduce the occurrence of yuzu skin. . More specifically, when the storage elastic modulus at 70 ° C. of the pressure-sensitive adhesive layer is 16 to 80 kPa, the generation of the yuzu 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, for example, 30 to 75 kPa.

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

(Production method of screen protection film)
The screen protection film of this embodiment can be manufactured as follows, for example. First, the above-mentioned pressure-sensitive adhesive composition is applied to an appropriate thickness on the above-described substrate 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, and a reverse coater. 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. On the pressure-sensitive adhesive layer, a release sheet may be stuck to protect the pressure-sensitive adhesive layer. Moreover, you may manufacture a screen protection film by the method of producing an adhesive layer on a peeling sheet and subsequently transferring on a base material.

  EXAMPLES Next, although an Example is shown and this invention is demonstrated further in detail, this invention is not limited to a following example.

[Manufacture of acrylic copolymer]
The acrylic monomers shown in Table 1 were mixed and polymerized in the proportions (mass%) shown in Table 1 to produce acrylic copolymers of Production Examples 1-6. Table 1 shows the results obtained by measuring the weight average molecular weight of the acrylic copolymer of each production example by gel permeation chromatography (GPC) method and displaying it in terms of standard polystyrene. In addition, the meaning of the symbol in Table 1 is as follows.
BA: butyl acrylate 2EHA: 2-ethylhexyl acrylate EA: ethyl acrylate MA: methyl acrylate AAc: acrylic acid 4HBA: 4-hydroxybutyl acrylate VAc: vinyl acetate

[Example 1]
The ingredients shown in Table 2 were mixed in 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 a mass part of solid content conversion. Tinuvin 477 (a hydroxyphenyl triazine UV absorber manufactured by BASF) was used as the triazine UV absorber. Coronate HL (manufactured by Tosoh Corporation) was used as the isocyanate-based crosslinking agent.

  The pressure-sensitive adhesive composition was cast on a release surface of a polyethylene terephthalate film (release sheet) coated with a silicone release agent using a knife coater. Then, it heated at 90 degreeC for 1 minute, the solvent was removed, and the 10-micrometer-thick adhesive layer was formed. Subsequently, the formed pressure-sensitive adhesive layer was pasted on the surface opposite to the hard coat layer of a polyethylene terephthalate film (trade name “Lumirror T60”, thickness 50 μm, manufactured by Toray Industries, Inc.) provided with a hard coat layer. The screen protective film of Example 1 was obtained.

[Example 2, Reference Examples 1 to 3, Comparative Example 1]
Example 1 except that the acrylic polymers of Production Examples 1 to 3 and 5 to 6 were used instead of the acrylic polymer of Production Example 4 and the components shown in Table 2 were mixed in the proportions shown in Table 2. In the same manner as in Example 2, screen protection films of Example 2, Reference Examples 1 to 3 and Comparative Example 1 were obtained.

[Measurement of cloudiness]
5 ml of the adhesive solution used in Examples 1 and 2, Reference Examples 1 to 3 and Comparative Example 1 was placed in a glass bottle (mouth inner diameter × body diameter × height: 14.5 mm × 27 mm × 55 mm, capacity 20 ml). After storing in an incubator at 80 ° C. for 24 hours to volatilize the solvent in the adhesive solution, it was taken out in a room temperature environment at 23 ° C. After adjusting the temperature for 24 hours in the same environment, the transparency of the adhesive was visually evaluated.
Evaluation is x for those in which white turbidity is observed and the visibility through the adhesive is not obtained, x for those in which white turbidity is observed but slight visibility through the adhesive is obtained, and ○ for those in which no cloudiness is observed and transparent did. White turbidity could be prevented by reducing the methyl acrylate monomer unit to 20% by mass or less based on the solid content of the acrylic copolymer.

[Measurement of image clarity]
The screen protective films of Examples 1-2, Reference Examples 1-3 and Comparative Example 1 were cut into 15 × 7 cm, and 30 sheets were laminated within 3 hours after the production of the screen protective film between two float glass plates. Sandwiched between. A load of 196 mN / cm ² was applied thereto, and the mixture was allowed to stand in a 70 ° C. environment for 1 week. Subsequently, it was left to stand for 1 day or more in an environment of 23 ° C. and 50% relative humidity to adjust the temperature and humidity. Thereafter, the screen protective film was taken out of the float glass plate and used as a sample for measuring image clarity.

  The image clarity measurement is performed using the image clarity measurement device “ICM-1T” (trade name, manufactured by Suga Test Instruments Co., Ltd.) with the adhesive layer of the screen protection film facing the light source. The sample was placed on a sample 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 screen protection films of Examples 1 and 2 and Reference Examples 1 to 3 were able to achieve 80% image clarity.

[Measurement of storage modulus]
The adhesive layers of the screen protective films of Examples 1-2, Reference Examples 1-3, and Comparative Example 1 were laminated to obtain a sample having a diameter of 8 mm × thickness of 3 mm. About these samples, the storage elastic modulus was measured by the torsional shear method in the environment of 1 Hz and 70 degreeC using the viscoelasticity measuring apparatus (The product name "MCR300" by Anton Paar company).

  The results are shown in Table 3. The adhesive layers of the screen protective films of Examples 1 and 2 and Reference Examples 1 to 3 in which the generation of yuzu skin was reduced had a storage elastic modulus at 70 ° C. in the range of 16 to 80 kPa. Moreover, white turbidity could be prevented by reducing the methyl acrylate monomer unit to 20% by mass or less based on the solid content of the acrylic copolymer.

[Example 3]
A silicone adhesive layer having a thickness of 20 μm was formed on one surface of a 100 μm-thick polyethylene terephthalate film (Lumirror T60, manufactured by Toray Industries, Inc.) as a supporting substrate.
Silicone adhesive formulation:
X-40-3229 (manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts by mass Platinum catalyst PL-50T (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5 part by mass The release sheet was peeled off from the screen protective film of Example 1, and the exposed acrylic system The pressure-sensitive adhesive layer was laminated on the surface of the support substrate on which the silicone pressure-sensitive adhesive layer was not formed.
When the screen protective film of Example 3 was cut to a size of 50 mm × 100 mm and laminated so that the silicone pressure-sensitive adhesive layer was in contact with the glass plate, bubbles were formed at the interface between the silicone pressure-sensitive adhesive layer and the glass plate. It was never done. Moreover, the screen protective film could be peeled off without leaving the silicone-based pressure-sensitive adhesive layer on the glass surface.

  ADVANTAGE OF THE INVENTION According to this invention, generation | occurrence | production of the yuzu skin can be reduced, the cloudiness of an adhesive layer can be prevented, and the screen protection film which has the outstanding ultraviolet-ray absorption performance can be provided. In addition, by having excellent ultraviolet absorption performance, it can be expected to prevent deterioration of the base film due to ultraviolet rays, prevention of deterioration of the adhesive itself, and prevention of fading, and it can be expected to be used as a window film for the purpose of cutting blue light and the like. .

Claims (5)

A screen protection film having a base material and an adhesive layer provided on the base material,
The base material is provided with a hard coat layer on the surface opposite to the pressure-sensitive adhesive layer,
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 10 to 20 parts by mass of the triazine-based ultraviolet absorber with respect to 100 parts by mass of the acrylic copolymer.
Using an image clarity measuring device in accordance with JIS K7374: 2007, the screen protective film adhesive layer is placed on the sample stage with the light source facing the light source, and the sample stage angle is 45 degrees, the transmission mode, and the comb width is 0.125 mm. A screen protective film having a measured image clarity of 80 to 100%. The screen protective film according to claim 1, wherein the triazine-based ultraviolet absorber is represented by the following general formula (A-1).

R ¹² , R ²² and R ³² are 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 are independently a hydrogen atom or an alkyl group, and may be a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, or may be a hydrogen atom or a methyl group, It may be a hydrogen atom.
R ¹⁴ , R ²⁴ and R ³⁴ are independently hydroxyl, alkyloxy, alkyl, hydroxyalkyloxy, alkyloxycarbonylalkyloxy, 3-alkyloxy-2-hydroxy-propyloxy or alkylcarbonyloxy. It is a group. The pressure-sensitive adhesive layer contains the acrylic copolymer as a main component, and the acrylic copolymer contains a polymerizable monomer unit having 4 to 5 carbon atoms having no crosslinkable functional group. 10 to 70% by mass based on the solid content of the polymer,
The screen protective film of Claim 1 or 2 whose storage elastic modulus in 70 degreeC of the said adhesive layer is 16-80 kPa.   The screen protection film according to any one of claims 1 to 3, wherein the acrylic copolymer has a weight average molecular weight of 500,000 to 900,000.   The screen protective film according to any one of claims 1 to 4, wherein a support base material and a silicone-based pressure-sensitive adhesive layer are laminated in this order on the pressure-sensitive adhesive layer.