JP6225673B2 - Window film - Google Patents

Description

  The present invention relates to a window film having excellent weather resistance.

In recent years, along with the seriousness of environmental problems such as global warming, space temperature adjustments for houses, automobiles and the like using window films having a light control layer have been promoted for the purpose of energy saving and CO ₂ reduction.
The window film is a function that adjusts the amount of incident heat rays and visible rays into the room by selectively absorbing, polarizing, reflecting, and transmitting light according to the incident angle of external light such as sunlight. It is a sheet.

The window film usually has a light control layer and an adhesive layer for bonding the light control layer to a window glass or the like. Here, since the above-described functions are exhibited by the shape of the light control layer, it is required that the light control layer be formed using a material that has high moldability and is less likely to be deformed over time. In addition, in order to improve indoor illuminance and room temperature using outside light, it is necessary to take in a larger amount of light into the room, and the light control layer may have high light transmittance. Desired. For this reason, ionizing radiation curable resin is suitable as the material for the light control layer.
However, the phenyl group in the structure of the ionizing radiation curable resin or the unreacted polymerizable unsaturated bond easily absorbs ultraviolet rays of external light, so that the light control layer has a disadvantage that it is liable to undergo photodegradation. Had. On the other hand, if a weathering agent such as an ultraviolet absorber or a light stabilizer is included to prevent deterioration of the light control layer, the ultraviolet light required for curing the resin is absorbed by the weathering agent when the light control layer is molded. Further, there is a problem that the curing reaction is inhibited and it becomes difficult to mold the light control layer into a desired shape.
Therefore, in the window film to be bonded to the inside of the window glass or the like with respect to the incident direction of external light, a weathering agent is included in the adhesive layer, and the deterioration of the light control layer such as ultraviolet rays contained in the external light By absorbing the light having the wavelength as described above, the light control layer is prevented from being deteriorated by improving the weather resistance of the window film.

  Patent Document 1 discloses a (meth) acrylic acid ester copolymer having a carboxyl group, a metal chelate crosslinking agent, and a triazine as a window film adhesive having high holding power, weather resistance, and ultraviolet absorption ability. An adhesive containing a UV absorber is disclosed. Moreover, the window film provided with the contact bonding layer containing the above-mentioned composition and the light control layer formed with ionizing radiation-curable resin is disclosed.

Japanese Patent No. 4881208

However, as a result of studies by the present inventors, even when an adhesive layer including the composition disclosed in Patent Document 1 is used, the ionizing radiation curable resin used for the light control layer has a phenyl group in the molecular structure. When the structural unit contains at least one of ethylene oxide-modified bisphenol A di (meth) acrylate, propylene oxide-modified bisphenol A di (meth) acrylate, and propoxylated ethoxylated bisphenol A di (meth) acrylate, The present inventors have found a problem that the effect of preventing deterioration of the light control layer cannot be obtained, and the weather resistance of the window film cannot be sufficiently improved.
Hereinafter, “ethylene oxide modification”, “propylene oxide modification”, and “propoxylated ethoxylation” may be referred to as “EO modification”, “PO modification”, and “EO / PO modification”, respectively. Further, “(meth) acrylate” means “acrylate or methacrylate”. The same shall apply hereinafter.

  This invention is made | formed in view of the said situation, and it aims at providing the window film excellent in the weather resistance.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that the wavelength selectivity of the ultraviolet absorber contained in the adhesive layer is EO-modified bisphenol A di (meth) acrylate, PO-modified bisphenol A di ( It has been found that it contributes to the suppression of deterioration of the light control layer containing a polymer having at least one of (meth) acrylate and EO / PO-modified bisphenol A di (meth) acrylate as a structural unit, and the present invention has been completed. It was.

  That is, the present invention is a window film having at least a light control layer and an adhesive layer, wherein the adhesive layer is disposed closer to the light source side of external light than the light control layer, and the adhesive layer is an acrylic film An adhesive polymer obtained by crosslinking a copolymer and a metal chelate crosslinking agent, and a benzotriazole ultraviolet absorber, and the light control layer includes EO-modified bisphenol A di (meth) acrylate and PO-modified bisphenol. A window film comprising a polymer having at least one of A di (meth) acrylate and EO / PO-modified bisphenol A di (meth) acrylate as a constituent unit is provided.

  According to the present invention, the modified bisphenol A di (meth), which is a structural unit of the polymer contained in the light control layer, of the external light incident on the window film, because the adhesive layer includes the above-described composition. Since the wavelength light that causes the deterioration of the acrylate is selectively and sufficiently absorbed by the benzotriazole-based ultraviolet absorber in the adhesive layer first, the deterioration of the light control layer can be suppressed. Thereby, it can be set as a window film with high weather resistance.

  In this invention, there exists an effect that it can be set as the window film which has high weather resistance.

It is a schematic sectional drawing which shows an example of the window film of this invention. It is the schematic perspective view and sectional drawing which show the other example of the window film of this invention. It is explanatory drawing for demonstrating the permeation | transmission path | route of the light in the louver type | mold light control layer whose light control part is a heat ray absorption part. It is explanatory drawing which shows an example of the longitudinal cross-sectional shape of a light control part. It is a schematic sectional drawing which shows the other example of the window film in this invention.

  Hereinafter, the window film of the present invention will be described in detail.

  The window film of the present invention has at least a light control layer and an adhesive layer, and the adhesive layer is disposed on the light source side of external light with respect to the light control layer, and the adhesive layer is an acrylic type An adhesive polymer obtained by crosslinking a copolymer and a metal chelate crosslinking agent, and a benzotriazole ultraviolet absorber, and the light control layer includes EO-modified bisphenol A di (meth) acrylate and PO-modified bisphenol. A polymer having at least one of A di (meth) acrylate and EO / PO-modified bisphenol A di (meth) acrylate as a constituent unit is included.

The window film of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of the window film of the present invention. The window film 10 of the present invention has at least the adhesive layer 1 and the light control layer 2. The adhesive layer 1 contains an benzotriazole ultraviolet absorber in an adhesive polymer obtained by crosslinking an acrylic copolymer and a metal chelate crosslinking agent, and the light control layer 2 includes EO modification, PO modification, And a polymer having at least one of EO / PO-modified bisphenol A di (meth) acrylate as a structural unit.
The window film of the present invention is used by being bonded to a window glass or the like so that the adhesive layer is disposed on the light source side of external light (L side in FIG. 1) rather than the light control layer.

Regarding the polymer in the light control layer, at least one of EO-modified bisphenol A di (meth) acrylate, PO-modified bisphenol A di (meth) acrylate, and EO / PO-modified bisphenol A di (meth) acrylate is used as a constituent unit. Having has means that the polymer has a state of being crosslinked and polymerized at the terminal group of at least one monomer of the modified bisphenol A di (meth) acrylate.
The polymer may have only one of the above modified bisphenol A di (meth) acrylates as a structural unit, or may have two or more types as a structural unit.

The inventors of the present invention are diligent about the combination of a light control layer containing a polymer having bisphenol A di (meth) acrylate as a structural unit and at least one of EO-modified, PO-modified, and EO / PO-modified, and an adhesive layer. As a result of repeated studies, it is difficult to suppress degradation of the light control layer when using triazine ultraviolet absorbers, cyanoacrylate ultraviolet absorbers, etc. among the ultraviolet absorbers contained in the adhesive layer. It has been found that when a triazole ultraviolet absorber is used, the deterioration of the light control layer is sufficiently suppressed.
The difference in effect due to the ultraviolet absorber is presumed to be due to the following reason. That is, the wavelength band that can be specifically absorbed varies depending on the type of the ultraviolet absorber, but the absorption wavelength band of the benzotriazole-based ultraviolet absorber is phenyl in the molecular structure of the modified bisphenol A di (meth) acrylate. It is considered that the group overlaps in a wide range with the wavelength band of light that is easily absorbed. For this reason, benzotriazole-based UV absorbers selectively emit light of a wavelength that causes deterioration of EO-modified, PO-modified, and EO / PO-modified bisphenol A di (meth) acrylates compared to other UV absorbers. It is estimated that it can be absorbed sufficiently.

  That is, according to the present invention, since the adhesive layer includes the above-described composition, among the external light incident on the window film, EO modification, PO modification, which are constituent units of the polymer that forms the light control layer, and Since the wavelength light causing the deterioration of the EO / PO-modified bisphenol A di (meth) acrylate is first sufficiently absorbed in the adhesive layer, the deterioration of the light control layer is suppressed, so that the weather resistance is high. It can be a window film.

  Hereinafter, the details of the window film of the present invention will be described.

1. Adhesive layer The adhesive layer in the present invention is disposed closer to the light source side of external light than the light control layer, and is an adhesive polymer obtained by crosslinking an acrylic copolymer and a metal chelate crosslinking agent, and benzo It contains a triazole ultraviolet absorber.

In addition, when the present inventors also examined the weather resistance of the adhesive layer itself, when an isocyanate-based crosslinking agent was used as a crosslinking agent constituting the adhesive polymer, the combined use with a benzotriazole-based UV absorber caused aging. Although yellowing of the adhesive layer was observed, it was found that yellowing did not occur when a metal chelate crosslinking agent was used instead of the isocyanate crosslinking agent.
That is, in the adhesive layer, not only can the light deterioration of the light control layer be suppressed by the contained benzotriazole-based UV absorber, but also by the combined use of the metal chelate crosslinking agent and the benzotriazole-based UV absorber, The adhesive layer itself can also have high weather resistance.

(1) Adhesive polymer The adhesive polymer in the adhesive layer is obtained by crosslinking an acrylic copolymer and a metal chelate crosslinking agent.

(A) Acrylic copolymer The acrylic copolymer is an adhesive main agent, and is preferably one that is crosslinked by heating in the crosslinking reaction with the metal chelate crosslinking agent described later. This is because in the case of crosslinking by light irradiation, the weather resistance of the adhesive layer after curing may be affected.
Examples of the acrylic copolymer include an acrylic ester copolymer obtained by copolymerizing a (meth) acrylic ester as a main component and a (meth) acrylic monomer.
In addition, (meth) acrylic acid ester means acrylic acid ester or methacrylic acid ester. The same applies to the (meth) acrylic monomer in the following description.

  Examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, and (meth) acrylic acid. Isobutyl, t-butyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, pentyl (meth) acrylate, isoamyl (meth) acrylate, neopentyl (meth) acrylate, Hexyl (meth) acrylate, heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate , Decyl (meth) acrylate, isodecyl (meth) acrylate, ( Data) undecyl acrylate, and (meth) dodecyl acrylate. These may be used alone or in combination of two or more. Among them, in the invention, butyl acrylate, isobutyl acrylate, t-butyl acrylate, butyl methacrylate, isobutyl methacrylate, and t-butyl methacrylate are preferable.

Examples of the (meth) acrylic monomer include monofunctional (meth) acrylate, bifunctional to tetrafunctional polyfunctional (meth) acrylate, and the like. About these (meth) acryl monomers, what has a functional group which becomes a crosslinking point with a metal chelate crosslinking agent copolymerizing with an acrylate ester is preferable.
Examples of the functional group serving as a crosslinking point include a hydroxyl group, a carboxyl group, an amide group, an amino group, an epoxy group, and a cyano group. In the (meth) acrylic monomer, one of these functional groups is included in the molecular structure. It is preferable to have 1 type to 4 types as a whole.

  Examples of the hydroxyl group-containing (meth) acrylic monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl acrylate, and the like.

  Examples of the carboxyl group-containing (meth) acrylic monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, and isocrotonic acid.

  Examples of the amide group-containing (meth) acrylic monomer include (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-methylol (meth) acrylamide, and N-methylolpropane (meth). Examples include acrylamide, N-methoxymethyl (meth) acrylamide, and N-butoxymethyl (meth) acrylamide.

  Examples of amino group-containing acrylic monomers include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, t-butylaminoethyl (meth) acrylate, and the like.

  Examples of the epoxy group-containing acrylic monomer include glycidyl (meth) acrylate and methyl glycidyl (meth) acrylate.

  Examples of the cyano group-containing acrylic monomer include acrylonitrile and methacrylonitrile.

Other (meth) acrylic monomers can be selected from, for example, the above-mentioned (meth) acrylic acid esters as monofunctional monomers. Also, for example, 1,6-hexanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, (poly ) Ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri ( (Meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, glycerin di (meth) acrylate, epoxy Rate, polyester acrylate, urethane acrylate, divinylbenzene, butyl di (meth) acrylate, and polyfunctional monomers such as hexyl di (meth) acrylate.
Furthermore, vinyl esters such as vinyl acetate, and styrene monomers such as styrene and α-methylstyrene are listed.

  Among them, as the (meth) acrylic monomer constituting the acrylic copolymer, butyl acrylate, isobutyl acrylate, t-butyl acrylate, butyl methacrylate, isobutyl methacrylate, and t-butyl methacrylate are preferably used. .

The acrylic copolymer is not particularly limited with respect to the copolymerization form, and may be any of a random copolymer, a block copolymer, and a graft copolymer. Preferably there is.
In addition, the weight average molecular weight (Mw) of the acrylic copolymer is not particularly limited as long as the adhesive layer in the present invention can exhibit a desired adhesive force, but it is in the range of 200000 to 1400000, and in particular, 600000 to 1000000. It is preferable to be within the range, particularly within the range of 750000 to 850000. If the weight average molecular weight is smaller than the above range, the adhesive force may decrease with a decrease in cohesive force. On the other hand, if the weight average molecular weight is larger than the above range, the window film of the present invention can be firmly bonded to the window glass or the like, but the adhesive force is too high and it may be difficult to peel off from the window glass at the time of replacement. is there.
In addition, the said weight average molecular weight is a value of polystyrene conversion at the time of measuring by gel permeation chromatography (GPC), and three LF-804 made by Showa Denko KK is used for the measurement, and THF is used as a developing solvent. Shall be used.

  Further, the content ratio of the acrylate ester and the (meth) acryl monomer in the acrylic copolymer is not particularly limited as long as the acrylate ester is a main component, and the adhesive layer in the present invention has a desired adhesive force and weather resistance. It can set suitably so that a property and an optical characteristic may be shown.

(B) Metal chelate crosslinking agent As the metal chelate crosslinking agent, those having a polyvalent metal such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, zirconium as the central metal are preferable. Among these, an aluminum chelate cross-linking agent whose center metal is aluminum is particularly preferable.

  Examples of the aluminum chelate crosslinking agent include diisopropoxy aluminum monooleyl acetoacetate, monoisopropoxy aluminum bis oleyl acetoacetate, monoisopropoxy aluminum monooleate monoethyl acetoacetate, diisopropoxy aluminum monolauryl acetoacetate, diisopropoxy Aluminum monostearyl acetoacetate, diisopropoxy aluminum monoisostearyl acetoacetate, monoisopropoxy aluminum mono-N-lauroyl-β-alanate monolauryl acetoacetate, aluminum trisacetylacetonate, monoacetylacetonate aluminum bis (isobutylacetate Acetate) chelate, monoacetylacetonate aluminum bis (2- Ethylhexyl acetoacetate) chelate, monoacetylacetonate aluminum bis (dodecyl acetoacetate) chelate, monoacetylacetonate aluminum bis (oleyl acetoacetate) chelate, and the like.

  Other metal chelate crosslinking agents include, for example, titanium tetrapropionate, titanium tetra-n-butyrate, titanium tetra-2-ethylhexanoate, zirconium-sec-butyrate, zirconium diethoxy-tert-butyrate, tri Examples include ethanolamine titanium dipropionate, ammonium lactate ammonium salt, and tetraoctylene glycol titanate.

  The above-mentioned metal chelate crosslinking agents may be used alone or in combination of two or more.

  The content of the metal chelate crosslinking agent is in the range of 1 to 30 parts by mass, particularly in the range of 3 to 20 parts by mass, particularly 5 to 15 parts by mass with respect to 100 parts by mass of the acrylic copolymer. It is preferable to be within the range. If the content of the metal chelate crosslinking agent is more than the above range, the crosslinking reaction with the acrylic copolymer is excessively accelerated and the curing becomes too dense, so that the adhesive layer is likely to deteriorate, and the window film On the other hand, if the amount is less than the above range, the crosslinking reaction is not sufficiently performed and the curing becomes too sparse, so that the curing is insufficient and the adhesive strength may be decreased.

(C) Adhesive polymer The above-mentioned adhesive polymer is obtained by crosslinking the above-mentioned acrylic copolymer and a metal chelate crosslinking agent, and further contains any monomer, oligomer, or other polymer. It may be cross-linked. Examples of the optional monomer include a hydroxyl group-containing (meth) acrylic monomer such as 2-hydroxypropyl acrylate.

(2) Benzotriazole-based ultraviolet absorber The benzotriazole-based ultraviolet absorber is not particularly limited, and for example, 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′-methylphenyl) ) -5-chlorobenzotriazole, 2- (2′-hydroxy 3′-isobutyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy 3′-isobutyl-5′-propylphenyl) ) 2′-hydroxyphenyl-5-chlorobenzotriazole-based UV absorbers such as 5-chlorobenzotriazole, 2- (2′-H Roxy 3 ′, 5′-di-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy5′-methylphenyl) benzotriazole and other 2′-hydroxyphenylbenzotriazole UV absorbers, 2- ( 2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4- (1,1,3,3-tetramethylbutyl) phenol, 2- (2H-benzotriazol-2-yl) Yl) -4,6-bis (1-methyl-1-phenylethyl) phenol, benzenepropanoic acid and 3- (2H-benzotriazol-2-yl) -5- (1,1-dimethylethyl) -4- Reactions in which an acryloyl group or a methacryloyl group is introduced into the benzotriazole skeleton, such as an ester compound with hydroxy (C7 to C9 side chain and straight chain alkyl) Type ultraviolet absorbers and the like. These may be used alone or in combination.
Among them, in the present invention, 2- (2′-hydroxy5′-methylphenyl) benzotriazole, 2- (2H-benzotriazol-2-yl) -6- (1-methyl-1-phenylethyl) -4 -(1,1,3,3-tetramethylbutyl) phenol, 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol, benzenepropanoic acid and Ester compounds with 3- (2H-benzotriazol-2-yl) -5- (1,1-dimethylethyl) -4-hydroxy (C7-C9 side chain and linear alkyl) are preferred.

  Examples of commercially available benzotriazole ultraviolet absorbers include Viosorb 520 (manufactured by Kyodo Yakuhin Co., Ltd.), Tinuvin 171, 384-2, 328, 99-2, PS, 928, 900, 1130 (manufactured by BASF) JF- 77, 80, 83, 832, JAST-500 (above, manufactured by Johoku Chemical Co., Ltd.), Sumisorb 200, 250, 300, 340 (above, manufactured by Sumitomo Chemical Co., Ltd.), KEMISORB 71, 73, 79, 279 (above, manufactured by Chemipro Chemical Co., Ltd.) ), RUVA-93 (manufactured by Otsuka Pharmaceutical Co., Ltd.), Seesorb 704, 706 (manufactured by Sipro Kasei Co., Ltd.), and the like.

  The content of the benzotriazole-based ultraviolet absorber in the adhesive layer is in the range of 0.1 to 25 parts by mass, particularly in the range of 1 to 25 parts by mass with respect to 100 parts by mass of the acrylic copolymer. In particular, it is preferably in the range of 3 parts by mass to 20 parts by mass. If the content of the benzotriazole ultraviolet absorber is larger than the above range, there may be a problem in appearance of the entire window film due to coloring of the adhesive layer. On the other hand, if the content is smaller than the above range, the adhesive layer May not sufficiently absorb ultraviolet rays, and the light control layer may deteriorate.

(3) Arbitrary material The adhesive layer in this invention may contain the light stabilizer etc. other than the above-mentioned composition from a viewpoint that a weather resistance further improves. The light stabilizer is preferably a hindered amine light stabilizer or the like, and may have a reactive group in the molecule. Examples of the light stabilizer include 1,2,2,6,6-pentamethyl-4-piperidinyl methacrylate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, and bis (1,2 , 2,6,6-pentamethyl-4-piperidinyl) sebacate, methyl (1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, 2,4-bis [N-butyl-N- (1- Cyclohexyloxy-2,2,6,6-tetramethylpiperidin-4-yl) amino] -6- (2-hydroxyethylamine) -1,3,5-triazine and the like.

  About content of the light stabilizer in a contact bonding layer, it should just exist in the range of 0 mass-7 mass parts with respect to 100 mass parts of acrylic copolymers, and is in the range of 0 mass parts-5 mass parts especially. It is particularly preferable that the content be in the range of 0 to 5 parts by mass.

In addition, the adhesive layer in the present invention may contain a silane coupling agent, an antioxidant, an adhesion-imparting agent, a cross-linking agent other than a metal chelate, a filler, a leveling agent and the like as optional materials.
The adhesion-imparting material is not particularly limited as long as it is generally used for an adhesive layer. For example, a rosin-based adhesion-imparting agent is suitable.

(4) Adhesive layer The gel fraction of the adhesive layer in the present invention is preferably within a range having an adhesive force capable of being bonded to glass or the like with a desired film thickness, and is 50% to 90% after curing. In particular, it is preferable to be in the range of 60% to 85%, particularly in the range of 70% to 80%. When the gel fraction of the adhesive layer is larger than the above range, the crosslink density increases to show a high adhesive force, and the window film of the present invention can be firmly bonded to a window glass or the like, but the adhesive force is high. In some cases, it may be difficult to peel off the window glass when it is pasted. In addition, when the crosslink density is too high, the adhesive layer may be easily deteriorated. On the other hand, when the gel fraction of the adhesive layer is smaller than the above range, the desired adhesive force may not be exhibited because the crosslinking density is low.
The gel fraction is a value measured by the following method.
(Measurement method of gel fraction)
The adhesive layer sandwiched between the separators is cut out at 10 cm × 10 cm square. The weight of the adhesive layer that has been cut out is rounded and placed in a bottle, and the weight of the adhesive layer before processing is measured from the difference. Next, the adhesive layer was immersed in MEK in a jar and prevented from volatilizing and allowed to stand for 3 hours, and then placed on a 10 cm × 10 cm 100 mesh net whose weight was measured in advance, and eluted from the waste liquid and the adhesive layer. Discard the monomer. It is dried at 60 ° C. for 24 hours with the adhesive layer placed thereon, and the weight of the adhesive layer after the mesh net after drying and the solvent immersion / drying is measured, and the adhesive layer after drying (after treatment) is determined from the difference from the initial weight. The weight was calculated and the gel fraction was determined from the following formula.
Gel fraction (%) = {(weight of adhesive layer after treatment (g)) / (weight of adhesive layer before treatment (g))} × 100

  The thickness of the adhesive layer is preferably in the range of 5 μm to 100 μm, and more preferably in the range of 10 μm to 75 μm. If the thickness of the adhesive layer is larger than the above range, the entire window film may be colored and may cause appearance problems. On the other hand, if the thickness is smaller than the above range, the adhesive layer cannot sufficiently absorb ultraviolet rays. In some cases, the light control layer may deteriorate.

The method for forming the adhesive layer is not particularly limited as long as it can be formed with a desired film thickness. For example, the optical control is performed using a coating solution in which the above-mentioned adhesive polymer material and benzotriazole ultraviolet absorber are dissolved in a desired solvent. A method of applying to one surface of the layer and heating to cure the coating film can be used. Among them, it is preferable to perform an aging treatment after curing in order to promote crosslinking.
Examples of the coating method for applying the coating solution include a knife coater, an applicator coater, a die coater, a comma coater, a gravure coater, and a roll coater. Moreover, as an aging process, it is preferable to perform the heat processing for about 3 to 7 days at 40 degreeC, for example.

2. Light Control Layer The light control layer in the present invention comprises at least one of EO-modified bisphenol A di (meth) acrylate, PO-modified bisphenol A di (meth) acrylate, and EO / PO-modified bisphenol A di (meth) acrylate. As a polymer.
In the present invention, the light control layer usually does not contain an ultraviolet absorber.

The light control layer in the present invention contains a polymer having at least one of the above-mentioned modified bisphenol A di (meth) acrylate as a structural unit, and has a structure capable of selectively transmitting heat rays and visible light. For example, a light control layer such as a louver type or a prism type may be used. Of these, a louvered light control layer is preferable. This is because, according to the incident angle of the external light, it is possible to secure the amount of light collected by reflecting the incident light and to selectively transmit and shield the heat rays.
Hereinafter, the description will be made by dividing into a louver type light control layer and other light control layers.

(1) Louver type light control layer The louver type light control layer in the present invention has a light transmission part having a plurality of grooves on one surface, and a light control part formed in the groove. In the louver-type light control layer, the light transmitting portion comprises at least one of EO-modified bisphenol A di (meth) acrylate, PO-modified bisphenol A di (meth) acrylate, and EO / PO-modified bisphenol A di (meth) acrylate. A polymer having a unit is included.

The louver type light control layer will be described with reference to the drawings. 2A is a schematic perspective view showing an example of a window film provided with a louver-type light control layer, and FIG. 2B is a sectional view taken along line xx of FIG. 2A.
2A and 2B, in the louver type light control layer 2A, a plurality of groove portions 13 are formed in a straight line and in parallel in the light transmitting portion 11, and the light control portion 12 is provided in the groove portion 13. It is what you have.

  In the louver-type light control layer, it becomes possible to select a light control method according to the material of the light control unit. For example, the light control unit is a low refractive index unit made of a resin material having a lower refractive index than that of the light transmission unit, so that all of the light due to the difference in refractive index is generated at the interface between the light transmission unit and the light control unit. By causing reflection, it is possible to increase the amount of collected light using the reflected light. Moreover, by making the light control part a heat ray absorbing part made of a material containing heat ray absorbing particles, it is possible to selectively transmit and shield the heat ray. Furthermore, by making the light control unit a light diffusing unit made of a material exhibiting concealment, light can be diffused and reflected at the interface between the light control unit and the light transmitting unit to increase the amount of light collected into the room. it can.

FIG. 3 is an explanatory diagram for explaining a light transmission path in the louvered light control layer in which the light control unit is a heat ray absorbing unit. The reference numerals not described in FIG. 3 are the same as those described in FIG. For example, as shown in FIG. 3A, in the summer when the solar altitude is high, the incident angle θ of the sunlight L with respect to the window glass 100 is large, so that a large amount of sunlight L is incident from the side surface of the heat ray absorbing portion 12a. At this time, visible light passes through the heat ray absorbing portion 12a and is taken into the room, while heat rays are absorbed by the heat ray absorbing portion 12a, so that the taking in the indoor side is blocked. In other words, in summer, visible light can be used to secure indoor illuminance, and an increase in indoor temperature due to heat rays can be suppressed.
On the other hand, as shown in FIG. 3B, in winter when the solar altitude is low, the incident angle θ of the sunlight L with respect to the window glass 100 becomes small and is incident from an angle close to perpendicular to the surface of the window glass 100. . For this reason, compared with the case of the summer shown in Fig.3 (a), the ratio of the sunlight L which injects into the light transmissive part 11 increases. Since the light transmission part 11 also transmits heat rays, both visible rays and heat rays can be taken into the room. In other words, in winter, it is possible to secure both indoor illumination using visible light and increase the indoor temperature due to heat rays.

  Hereinafter, each configuration of the louver type light control layer will be described.

(A) Light transmissive part The light transmissive part comprises at least one of EO-modified bisphenol A di (meth) acrylate, PO-modified bisphenol A di (meth) acrylate, and EO / PO-modified bisphenol A di (meth) acrylate. As a polymer.
The modified bisphenol A di (meth) acrylate has an average functional group number of about 2.

  The light transmission part may contain arbitrary additives in addition to the above-mentioned materials. Examples of the additive include a light stabilizer, a release agent, a polymerization inhibitor, a crosslinking agent, an antioxidant, a plasticizer, an antifoaming agent, and a filler. It should be noted that the UV absorber is usually not included. Moreover, it is preferable not to contain a light stabilizer from the viewpoint of shape stability.

The thickness of the light transmitting portion is appropriately selected according to the height of the groove portion, and is, for example, in the range of 10 μm to 300 μm, particularly in the range of 25 μm to 250 μm, particularly in the range of 50 μm to 200 μm. Is preferred. If the thickness of the light transmission part is larger than the above range, the incident light is absorbed in the light transmission part, the amount of light emitted to the indoor side is reduced, and the visibility of the window film of the present invention may be reduced. On the other hand, if it is smaller than the above range, it may be difficult to form the groove in a desired shape.
In addition, the thickness of the light transmission part is the thickness of the louver type light control layer, and is a part indicated by T1 in FIG.

  The shape and the like of the groove part of the light transmission part are the same as the shape and the like of the light control part which will be described later, and the description in this section is omitted.

The refractive index of the light transmission part is appropriately selected according to the type of the light control part, and is, for example, in the range of 1.40 to 1.80, particularly in the range of 1.45 to 1.70, particularly 1. It is preferable to be within the range of 50 to 1.65.
The refractive index of the light transmission part is measured at a wavelength of 589 nm under the condition of a temperature of 23 ° C. using an Abbe refractometer (manufactured by Atago Co., Ltd.) according to the refractive index measurement method defined in JIS K7142. Measured using a sodium light source. In the following description, the refractive index measurement method is measured by this method.

Further, the visible light transmittance of the light transmitting portion is preferably 70% or more, more preferably 80% or more, and particularly preferably 90% or more. When the light transmission part has the above visible light transmittance, a decrease in the amount of light emitted to the indoor side due to absorption of incident light in the light transmission part is suppressed, and the visibility of the window film of the present invention can be improved. .
The visible light transmittance was measured by using a spectrophotometer (“UV-2450” manufactured by Shimadzu Corporation, JIS K 0115 compliant product) and a PET film manufactured by Toyobo (product number: Cosmo Shine A4300, thickness 100 μm). It confirms by measuring within the measurement wavelength of 380 nm-780 nm with respect to the 10-micrometer-thick light transmission part formed above.

(B) Light control part A light control part is formed in the groove part of a light transmission part. That is, the light control part and the groove part usually have the same shape. Further, the light control unit can select the function according to the constituent material.
Hereinafter, an example of an assumed light control unit will be described.

(I) Low refractive index portion The low refractive index portion is made of a resin material that exhibits a lower refractive index than the light transmitting portion. By making the light control part a low refractive index part, total reflection of light due to the difference in refractive index can be caused at the interface between the light transmission part and the light control part, and the amount of collected light using the reflected light can be increased. Can be planned.

The material of the low refractive index portion may be a transparent resin having a refractive index lower than that of the light transmitting portion, and is preferably an ionizing radiation curable resin. Examples of the ionizing radiation curable resin include an ultraviolet curable resin, an electron beam curable resin, a visible light curable resin, a near infrared curable resin, and the like. Among them, an ultraviolet curable resin and an electron beam curable resin are included. preferable.
As said ultraviolet curable resin and electron beam curable resin, it can select from the polymerizable oligomer thru | or prepolymer conventionally used conventionally, and can be used suitably. For example, polymerizable oligomers or prepolymers, especially polyfunctional polymerizable oligomers or prepolymers can be mentioned. Polymerizable oligomers or prepolymers include oligomers and prepolymers having radically polymerizable unsaturated groups in the molecule, such as epoxy (meth) acrylate, urethane (meth) acrylate, and polyether urethane (meth) acrylates. , Caprolactone urethane (meth) acrylate, polyester (meth) acrylate, polyether (meth) acrylate oligomers and prepolymers, ethylene oxide (EO) modification, propylene oxide (PO) modification, propoxylated ethoxylation, etc. Examples include oligomers and prepolymers containing bisphenol A di (meth) acrylate and the like as structural units. These may be used alone or in combination of two or more.

  Moreover, when using an ultraviolet curable resin, it is preferable to use a photoinitiator together. As the type of the photopolymerization initiator, those conventionally used can be used. As a content rate of a photoinitiator, it is preferable that it is about 0.1-5 mass parts with respect to 100 mass parts of ultraviolet curable resin.

  Moreover, although the said low refractive index part may contain other arbitrary materials, it is preferable not to contain an ultraviolet absorber and a light stabilizer from a viewpoint of shape stability.

  The refractive index of the low refractive index portion may be lower than the refractive index of the light transmitting portion, and is preferably in the range of 1.40 to 1.55, for example.

  The low refractive index portion preferably has a desired visible light transmittance. Specifically, since it is the same as the visible light transmittance of the light transmitting portion described above, description thereof is omitted here.

(Ii) Heat ray absorbing portion The heat ray absorbing portion is made of a material containing heat ray absorbing particles as a heat ray absorbent. By making the light control unit a heat ray absorbing unit, it is possible to selectively transmit and shield heat rays.

(Heat ray absorbing particles)
The heat ray absorbing particles may be particles that transmit visible light and absorb heat rays, that is, particles that have absorption characteristics in the infrared light region and transmission properties in the visible light region. Is preferably 50% or more, more preferably 60% or more, and particularly preferably 70% or more. The infrared absorptivity is preferably 50% or more, for example, preferably 60% or more, and particularly preferably 70% or more.
The visible light transmittance is obtained by adding a composition for forming a heat-absorbing part in which 95% by mass of a binder resin to be described later contains 5% by mass of heat-absorbing particles to a total amount of 100% by mass. Product name: Cosmo Shine A4300, 100 μm thick), coated at a film thickness of 1 μm, and using a spectrophotometer (manufactured by Shimadzu Corporation, UV-2450, JIS K 0115 compliant), measurement wavelength 380 nm to 780 nm It is the average value of the visible light transmittance at each wavelength when measured within the range.
Moreover, the said infrared absorptivity is the average value of the infrared absorptivity in each wavelength when it measures within the measurement wavelength of 780 nm-2500 nm using the sample and measuring method similar to the measurement of the visible light transmittance mentioned above. is there.

In addition, as the heat ray absorbing particles, inorganic nanoparticles can be used. Specifically, antimony tin oxide (ATO), indium tin oxide (ITO), lanthanum hexaboride (LaB ₆ ), aluminum-doped oxide. Nanoparticles of zinc, indium-doped zinc oxide, gallium-doped zinc oxide, tungsten oxide, cerium hexaboride, anhydrous zinc antimonate and copper sulfide, or a mixture thereof can be used. Among them, it is preferable to use antimony tin oxide (ATO), indium tin oxide (ITO), lanthanum hexaboride (LaB ₆ ), or a mixture thereof.
The heat ray absorbing particles may be transparent or non-transparent, but are preferably transparent.

The heat-absorbing particles are preferably nanoparticles, and the average particle diameter (D ₅₀ ) thereof is, for example, in the range of 10 nm to 200 nm, particularly in the range of 20 nm to 150 nm, particularly in the range of 30 nm to 100 nm. Is preferred. If the average particle diameter of the heat ray absorbing particles is larger than the above range, haze may occur and the transparency of the window film of the present invention may be lowered. On the other hand, if the average particle size is smaller than the above range, the heat rays cannot be sufficiently absorbed. There is a case.
In addition, the said average particle diameter is the value calculated | required by observing the particle | grains of a heat ray absorption particle with an electron microscope, and arithmetic mean.

(Binder resin)
The heat ray absorbing part preferably has at least a binder resin in addition to the heat ray absorbing particles described above. The binder resin is not particularly limited as long as it is a material that can be cured by irradiation with ionizing radiation. The binder resin is polymerized based on a monomer, oligomer, prepolymer or polymer having a radical polymerizable active group in the structure. An ionizing radiation curable resin is preferable. Examples of the ionizing radiation curable resin include an ultraviolet curable resin, an electron beam curable resin, a visible light curable resin, and a near infrared curable resin. Among these, it is preferable to use an ultraviolet curable resin and an electron beam curable resin. Specifically, reactive oligomers such as epoxy acrylate, urethane acrylate, polyether acrylate, polyester acrylate, polythiol, vinyl pyrrolidone, 2-ethylhexyl acrylate, β-hydroxy acrylate, tetrahydrofurfuryl acrylate, many Examples thereof include reactive monomers such as functional (meth) acrylates.

  The binder resin preferably contains a photoinitiator. This is because the binder resin can be cured by irradiating ultraviolet rays having a wavelength of 300 nm to 400 nm. The photoinitiator can be appropriately selected according to the type of ionizing radiation to be irradiated. For example, a ketone or acetophenone photoinitiator, specifically, Sandley 1000, Darocur 1163, Darocur 1173, Irgacure 183, Irgacure 651, or the like is used. be able to. In addition, the content rate of the said photoinitiator can be suitably adjusted according to the quantity of binder resin, for example, it is preferable that it is about 0.1-5 mass parts with respect to 100 mass parts of binder resin. .

  The binder resin in the heat ray absorbing portion preferably has a small refractive index of visible light. This is because the heat ray absorbing particles described above have a large refractive index of visible light, and thus the refractive index of the entire heat ray absorbing portion can be adjusted by reducing the refractive index of the binder resin.

  The binder resin content in the heat-absorbing part is within the range of 40% to 98% by mass, and particularly within the range of 50% to 95% by mass in the total mass (100% by mass) of the heat-absorbing part. Is preferred. If the binder resin content is higher than the above range, the concentration of the heat-absorbing particles may become thin and heat rays may not be sufficiently absorbed. On the other hand, if the binder resin content is lower than the above range, the adhesiveness to the light transmission part may be poor. There is.

(Heat ray absorption part)
The heat ray absorbing portion may contain any material such as a photoinitiator in addition to the heat ray absorbing particles and the binder resin described above, but may not contain an ultraviolet absorber or a light stabilizer from the viewpoint of shape stability. preferable.

  It is preferable that the heat ray absorbing portion has a desired visible light transmittance and infrared absorption rate. Specifically, since it is the same as the visible light transmittance and infrared absorptivity of the heat ray absorbing particles described above, description thereof is omitted here.

Moreover, it is preferable that a heat ray absorption part has a desired refractive index with respect to visible light, and it is preferable that especially the difference with the refractive index with respect to visible light in a light transmissive part is small. If the difference in refractive index between the light control unit and the light transmission unit is large, a plurality of stripes parallel to the vertical direction of the image displayed on the window film enter, and the color of the image decomposes in the direction of the above stripes. In some cases, the image becomes unclear (hereinafter referred to as “multiple image”), and high visibility cannot be obtained. This is because there is a bias in the diffusion of the emitted light between the visible light transmitted through the light control unit and the light transmission unit and the visible light transmitted through only the light transmission unit.
The refractive index of the heat-absorbing part is specifically in the range of 1.40 to 1.80, in particular in the range of 1.45 to 1.70, particularly in the range of 1.50 to 1.65. It is preferable. The refractive index difference between the light transmitting part and the heat ray absorbing part is preferably 0.025 or less, more preferably 0.015 or less.

(Iii) Light diffusion part The light diffusion part is made of a material exhibiting concealment. By making the light control unit a light diffusing unit, light can be diffused and reflected at the interface between the light control unit and the light transmitting unit to increase the amount of light collected indoors.

As a material for the light diffusion portion, a material having a concealing property is preferable, and examples thereof include a white pigment and a silver pigment. Examples of the white pigment include metal oxides such as titanium oxide, titanium dioxide, magnesium oxide, and zinc oxide. Examples of the silver pigment include metals such as aluminum and chromium.
The light diffusing part may contain other arbitrary materials as necessary, but preferably does not contain an ultraviolet absorber or a light stabilizer.

  Further, from the viewpoint of facilitating diffuse reflection of light at the interface between the light diffusing portion and the light transmitting portion, the light diffusing portion may have the mat surface as the interface with the light transmitting portion.

(Iv) Light Control Unit The light control unit has a vertical cross-sectional shape of a straight line or a curve having two or more hypotenuses on at least one of two side surfaces constituting a triangle, square, rectangle, trapezoid, and vertical cross-sectional shape. The taper shape comprised, the shape whose four sides are curves, etc. are mentioned. Further, the corner of the light control unit may have a curved surface according to the shape of the groove, and the side of the side surface forming the vertical cross-sectional shape may be a straight line or a curved line. FIG. 4 is an explanatory view showing an example of the vertical cross-sectional shape of the light control unit. FIG. 4 (a) is a trapezoidal shape, and FIG. 4 (b) is composed of two straight lines with hypotenuses on both sides. FIG. 4C shows an example of the longitudinal cross-sectional shape of the light control unit having a triangular shape having a curvature at a corner.

  The shape of the light control unit in plan view is not particularly limited, and may be, for example, a linear shape or a shape such as a curve. Furthermore, the arrangement of the light control units in plan view may be arranged in parallel, arranged in parallel, or randomly arranged in the other direction. In particular, as shown in FIG. 2A, it is preferable that the light control unit 12 be linearly arranged in parallel in a plan view.

  The height of the light control unit is preferably in the range of 10 μm to 300 μm, more preferably in the range of 25 μm to 250 μm, and particularly preferably in the range of 50 μm to 200 μm. Further, the height of the light control unit is in the range of 30% to less than 100% of the thickness of the light transmission unit, in particular in the range of 40% to 97.5%, particularly in the range of 50% to 95%. Is preferred. This is because the thickness of the window film increases relatively and the flexibility may decrease. The height of the light control unit is a part indicated by T2 in FIG.

The width of the light control unit can be appropriately set according to the type of the light control unit. For example, when the light control part is a low refractive index part or a heat ray absorption part, the widest part of its width is within the range of 5 μm to 50 μm, especially within the range of 7 μm to 45 μm, especially within the range of 10 μm to 40 μm. Preferably there is. When the width of the light control unit is larger than the above range, visible light may not be easily transmitted as the whole window film. On the other hand, when the width is smaller than the above range, the light control unit may not have a desired height. This is because the desired light reflecting function and heat ray absorbing function may not be achieved.
When the light control unit is a light diffusion unit, the width is preferably in the range of 5 μm to 150 μm. When the width of the light control unit is larger than the above range, it is difficult to obtain a light scattering effect. The width of the light control unit refers to the widest portion in the longitudinal cross-sectional shape of the light control unit, and is a portion indicated by W in FIG.

  The length of the light control unit is appropriately selected according to the size of the desired window film. The length of the light control unit refers to the length in the longitudinal direction in plan view.

The pitch width of the light control unit can be appropriately set according to the type of the light control unit.
For example, when the light control unit is a low refractive index unit or a heat ray absorption unit, the pitch width is preferably within a range of 15 μm to 200 μm, more preferably within a range of 20 μm to 150 μm, and particularly preferably within a range of 25 μm to 100 μm. When the pitch width is larger than the above range, it is difficult for outside light having a large incident angle to enter the light control unit, and the function by the light control unit may not be sufficiently performed. This is because it may be difficult to transmit visible light in the light transmitting portion.
When the light control unit is a light diffusion unit, the pitch width is preferably in the range of 10 μm to 200 μm. If the pitch width is smaller than the above range, the amount of light collected may not increase due to light diffusion.
The pitch width of the light control unit refers to the distance between the centers of adjacent light control units, and is a portion indicated by P in FIG.

(C) Louver type light control layer The surface including the light control part of the louver type light control layer may be flat or uneven, and may be appropriately selected according to the function of the light control layer. it can. For example, in a window film that requires high visibility, it is preferable that the surface of the louver-type light control layer is flat. The average surface roughness (Ra) of the louver type light control layer is preferably in the range of 0.1 nm to 100 nm, more preferably in the range of 0.1 nm to 20 nm, and particularly preferably in the range of 0.1 nm to 10 nm.
In the case where the surface has irregularities, there is a bias in the diffusion of light on the incident surface or the exit surface between the region where the incident surface or exit surface of the external light is flat and the region where the surface is concave or convex. For this reason, the amount of emitted light is biased to induce a light diffraction phenomenon and an interference phenomenon, whereby a multiple image appears on the window film and visibility may be lowered.
The average surface roughness (Ra) is measured in a measurement environment of 23 ° C. in accordance with the provisions of JIS B0601 2001, and only the reference length is extracted from the roughness curve in the direction of the average line. When the X axis is taken in the direction of Y and the Y axis is taken in the direction of the vertical magnification, and the roughness curve is represented by y = f (x), the value is calculated by the following equation (1).

  Further, the surface including the light control portion of the louver type light control layer may have a planarization layer, a scattering layer, or the like. This is because the occurrence of the light diffraction phenomenon and the interference phenomenon can be suppressed, and the deterioration of the visibility of the window film due to the appearance of multiple images can be prevented. Moreover, you may have a photocatalyst layer for the purpose of air quality control.

  As shown in FIG. 2B, the louver type light control layer may have a surface that does not include the surface of the light control unit 12 on the same surface as a bonding surface with the adhesive layer 1. It is good also considering the surface side which contains the surface on the same surface as a bonding surface.

The method for forming the louver type light control layer is not particularly limited as long as it is a method capable of forming a light transmitting portion having a plurality of groove portions of a desired shape on the surface and forming the light control portion in the groove portion.
The method for forming the light transmissive part is not particularly limited. For example, after the composition for forming the light transmissive part including the material for the light transmissive part is applied on the substrate, the shaping plate having the convex part is formed. It can be formed by crosslinking and curing in the pressed state. The shaped plate used at this time has a plurality of convex portions on the surface, and the inverted shape and the size of the convex portions usually correspond to the shape and size of the groove portion.

The method for applying the light transmissive portion forming composition is not particularly limited as long as it can be applied with a uniform film thickness. For example, spin coating, die coating, dip coating, bar coating, and the like. A coating method, a gravure printing method, a screen printing method, or the like can be used.
As a method for curing the composition for forming a light transmission part, curing by irradiation with ionizing radiation is preferable, and among these, ultraviolet rays or electron beams are preferably used from the viewpoint of practicality. About hardening conditions etc., it can set suitably according to the kind of material.

  The method for forming the light control unit is not particularly limited. For example, a method for applying a light control unit forming composition containing a material for the light control unit, filling the groove of the light transmission unit, and curing it. Can be used.

The application method of the composition for forming a light control part is not particularly limited as long as it can be sufficiently filled in at least the groove part. Wiping method, coating method, dry laminating method, extrusion laminating method Etc. can be used. Further, when applying the light control part forming composition, the excessive amount of the light control part forming composition that has flowed out from the groove to the surface of the light transmitting part may be removed by scraping with a squeegee or the like. Good.
As the curing method of the composition for forming a light control unit, curing by irradiation with ionizing radiation such as ultraviolet rays and electron beams is preferable, and curing conditions and the like can be appropriately set according to the material and the type of ionizing radiation. .

(2) Other Light Control Layer As the other light control layer, for example, a prism type light control layer can be used. The prism type light control layer has a function of controlling the incident direction of light to the indoor side by polarizing and reflecting external light. For example, as shown in FIG. 5, the prism-type light control layer 2B has a structure including a plurality of unit prisms 31 having a trapezoidal cross section. By generating the polarized light, it is possible to control the incident direction when the external light enters the room. Here, the unit prism is a polymer having at least one of EO-modified bisphenol A di (meth) acrylate, PO-modified bisphenol A di (meth) acrylate, and EO / PO-modified bisphenol A di (meth) acrylate as a constituent unit. Is included.
Note that the space between adjacent unit prisms (portion indicated by 32 in FIG. 5) may be filled with air, or may be filled with a material having a different bending rate from that of the unit prism.

  The details of the structure of the unit prism and the like can be the same as the details of the unit prism described in, for example, Japanese Patent Application Laid-Open No. 2013-15569.

  The thickness of the prism type light control layer is preferably 10 μm or more and 200 μm or less. If the film thickness is smaller than the above range, the optical performance may be insufficient, or the prism type light control layer may be finely processed and the accuracy may be lowered. On the other hand, if it is larger than the above range, peeling from the mold may be difficult when the prism type light control layer is molded.

3. Base Material The window film of the present invention may have a base material. The substrate is usually provided on the surface opposite to the surface on which the adhesive layer of the light control layer is provided.

  The base material is not particularly limited as long as it has light transmittance and does not adversely affect visibility. For example, a sheet or film made of a resin having transparency can be used, and in particular, a film Is preferred.

  The resin used for the substrate may be any resin that has transparency and strength that can support the light control layer and the like. For example, polyethylene terephthalate, polycarbonate, polyester, polyurethane, polyvinyl alcohol, polycarbonate, vinyl chloride, fluororesin, rubber and the like can be used. Of these, polyethylene terephthalate and polycarbonate are preferable from the viewpoint of transparency and strength. Further, the base material may contain an antioxidant, an ultraviolet absorber and the like.

  The base material may be subjected to surface treatment or the like on one side or both sides as necessary. Surface treatments include corona discharge treatment, chromic acid treatment (wet), flame treatment, hot air treatment, surface treatment by oxidation methods such as ozone ultraviolet irradiation treatment, surface treatment by roughening methods such as sandblasting and solvent treatment methods, chemical treatment Surface treatment and the like.

  The film thickness of the substrate can be appropriately set according to the use, but is usually within the range of 5 μm to 200 μm, and preferably within the range of 10 μm to 150 μm. If the film thickness of the substrate is smaller than the above range, curls, wrinkles and the like are likely to enter, and the strength of the window film may not be obtained.

4). Peeling layer The window film of the present invention preferably has a peeling layer on the adhesive layer. By having the peeling layer, adhesion of dust or the like to the adhesive layer can be prevented, and deterioration of the visibility of the window film due to dirt can be prevented. Further, when the window film wound up in a roll shape is unwound, the surface of the adhesive layer becomes rough, and the occurrence of unwinding failure can be prevented.

  The material of the release layer is not particularly limited as long as it is generally used. Examples thereof include acrylic and methacrylic resins such as polymethyl acrylate and polymethyl methacrylate, polyvinyl chloride resin, cellulose resin, silicon resin, chlorinated rubber, casein, various surfactants, and metal oxides. These materials may be used alone or in combination of two or more.

5. Arbitrary layer The window film of this invention may have arbitrary layers other than the above-mentioned structure. For example, an overcoat layer may be provided between the adhesive layer and the light control layer from the viewpoint of improving the adhesion between the adhesive layer and the light control layer and improving the appearance.

  As a material for the overcoat layer, an ionizing radiation curable resin is preferably used, and can be appropriately selected from a polymerizable oligomer or a prepolymer. Among these, it is preferable to use a polyfunctional polymerizable oligomer or prepolymer. Examples of the polymerizable oligomer or prepolymer include oligomers and prepolymers having a radically polymerizable unsaturated group in the molecule, such as epoxy (meth) acrylate, urethane (meth) acrylate, and polyether urethane (meth) acrylate. Examples include caprolactone urethane (meth) acrylate, polyester (meth) acrylate, and polyether (meth) acrylate oligomers and prepolymers. The weight molecular weight is preferably about 1000 to 5000.

  In addition to the above polyfunctional polymerizable oligomer, the ionizing radiation curable resin includes a caprolactone urethane (meth) acrylate obtained by a reaction of a caprolactone polyol, an organic isocyanate and a hydroxy acrylate, and a polybutadiene oligomer side. A polymer urethane (meth) acrylate such as a highly hydrophobic polybutadiene (meth) acrylate having a (meth) acrylate group in the chain can be used in combination. This is because the weather resistance of the overcoat layer can be improved. Among these, it is preferable to use a caprolactone-based material in combination.

  In addition, when polyfunctional urethane (meth) acrylate is used as the material for the overcoat layer, a diluent such as monofunctional (meth) acrylate such as methyl (meth) acrylate is used for the purpose of adjusting the viscosity. Can be used in combination. The monofunctional (meth) acrylate may be used alone or in combination of two or more, or a low molecular weight polyfunctional (meth) acrylate may be used in combination. Moreover, as a diluent, applicability | paintability can also be ensured using said monomer.

  The overcoat layer may contain an ultraviolet absorber, a light stabilizer, a silicate compound, and the like. The details of the ultraviolet absorber and the light stabilizer are the same as those described above.

  The thickness of the overcoat layer is preferably in the range of 0 μm to 40 μm, more preferably in the range of 0 μm to 20 μm, and particularly preferably in the range of 0 μm to 10 μm.

  As a method for forming the overcoat layer, for example, a coating solution obtained by diluting the above-described material with a desired solvent can be prepared, and the coating solution can be applied on a substrate. As an application method, for example, an applicator coat, a beer bar coat, a wire bar coat, a gravure coater, a die coater or the like can be used.

  Moreover, you may have a flaw-resistant layer, a self-cleaning layer, etc. in the surface side which does not have the contact bonding layer of a light control layer as another arbitrary layer. In addition, when the light control layer is bonded with a base material, these layers are arrange | positioned on one surface of a light control layer through the said base material. The details of the scratch-resistant layer, the self-cleaning layer and the like can be the same as those of the overcoat layer described above.

6). Window Film The visible light transmittance of the window film of the present invention is preferably such that the visible light transmittance when the incident angle of external light is 0 ° is 65% or more, particularly 70% or more, particularly 85% or more. Preferably there is. By making the visible light transmittance within the above range when the incident angle of external light is 0 °, the appearance and the like can be clearly observed. In addition, since the amount of visible light taken into the room or the like increases, the illuminance in the room can be secured by using outside light. The incident angle here refers to the angle θ shown in FIG.
The visible light transmittance was measured using a infrared visible ultraviolet spectrophotometer (UV3100PC, manufactured by Shimadzu Corporation) and measured in the wavelength range of 380 nm to 780 nm according to JIS A5759-2008. It is calculated by the calculation formula prescribed in 1.

  As the usage mode of the window film of the present invention, the effect is exhibited by arranging the adhesive layer on the light source side of the external light with respect to the light control layer, so that it is mainly used for indoor use.

7). Applications The window film of the present invention can be used by being attached to, for example, vehicles such as buildings, houses, trains, cars, buses, window glass of airplanes, ships, openings, and the like.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

[Example 1]
(Formation of light control layer)
The light control layer was formed by the following method.

(1) Formation of light transmissive part and groove part On one surface of a continuous belt-like transparent biaxially stretched PET film (thickness 50 μm), a liquid light transmissive part forming composition A having the following composition was cured. The film was applied so that the film thickness was 100 μm.

<Light transmission part forming composition A>
-EO-modified bisphenol A diacrylate (product name: A-BPE-10, manufactured by Nakamura Chemical Co., Ltd.) ... 100 parts by mass- Benzophenone photoinitiator (photopolymerization initiator, product name: Irgacure 184, manufactured by Ciba Specialty Chemicals) ) 1 part by mass

The main cutting surface has a trapezoidal convex portion with a height of 63 μm, a plate surface side width of 28 μm, and a width far from the plate surface of 24 μm. A roll mold was prepared in which convex groups (same shape as the light control unit and reverse irregularities) arranged in parallel with each other with a plurality of strips at a period of 78 μm were prepared.
In a state where the composition A for forming a light transmission part is sandwiched between the roll mold and the PET film, the composition A for light transmission part formation is crosslinked and cured by performing ultraviolet irradiation using a mercury lamp, The roll mold was peeled off to form a light transmission part having a groove part on the surface of the PET film.
The shape of the groove part was a reversal shape of the convex group of the roll mold described above, that is, a concave group having a trapezoidal longitudinal cross-sectional shape.

(2) Formation of light control part Next, the light control part as a low refractive index part was formed in the groove part. First, a liquid light control part forming composition having the following composition was prepared, and after applying this to the groove part of the light transmission part, squeezing with an iron doctor blade and filling only into the concave groove, The light control part was formed by irradiating with ultraviolet rays and crosslinking and curing to obtain a louver type light control layer. The refractive index of the light transmission part was 1.55, and the refractive index of the light control part was 1.47. The method of measuring the refractive index is the same as the method described in “2. Light control layer”.

<Light control part forming composition>
-Polyethylene glycol # 600 diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., A-600) ... 99 parts by mass-1-hydroxycyclohexyl-phenyl-ketone (photopolymerization initiator, product name: Irgacure 184, manufactured by BASF) ... 1 part by mass

(Formation of overcoat layer)
On the surface including the light control part of the louver type light control layer, the above-described resin composition A for forming a light transmission part is applied and cured by ultraviolet irradiation to form a smooth overcoat layer (Ra = 0.12 nm). Formed.

(Formation of adhesive layer)
Benzotriazole ultraviolet absorber A as an ultraviolet absorber for 100 parts by mass of an acrylic adhesive (product name: SK Dyne 1429DT, solid content 30%, manufactured by Soken Chemical Co., Ltd.) mainly composed of an acrylic ester copolymer 4 parts by mass (product name: Biosorb 520, manufactured by Kyodo Yakuhin Co., Ltd.) (1.18 parts by mass in terms of solid content) was stirred and dissolved with a scriber at 50 rpm for 30 minutes. Furthermore, 10 parts by mass (3 parts by mass in solid content) of an aluminum chelate crosslinking agent (product name: AD-5A, manufactured by Soken Chemical Co., Ltd.) as a crosslinking agent was added and stirred for 10 minutes to obtain an adhesive layer coating solution.
Then, the adhesive layer coating solution was applied on the surface of the light control layer having no overcoat layer with an applicator so that the wet film thickness was 83 μm, and dried at 80 ° C. for 2 minutes. An adhesive layer (film thickness after drying: 25 μm) containing the benzotriazole ultraviolet absorber A was formed.
A light release separator film having a small silicon transferability (product name: P381031, film thickness: 38 μm, manufactured by Lintec Corporation) was laminated on the adhesive layer, and aged at 40 ° C. for 5 days to obtain a window film.

[Example 2]
A window film was obtained in the same manner as in Example 1 except that the ultraviolet absorber in the adhesive layer coating solution was benzotriazole ultraviolet absorber B (product name: Tinuvin 900, manufactured by BASF).

[Example 3]
A window film was obtained in the same manner as in Example 1 except that the ultraviolet absorber in the adhesive layer coating solution was benzotriazole-based ultraviolet absorber C (product name: Tinuvin 928, manufactured by BASF).

[Example 4]
A window film was obtained in the same manner as in Example 1, except that the ultraviolet absorber in the adhesive layer coating solution was benzotriazole-based ultraviolet absorber D (product name: Tinuvin 171, manufactured by BASF).

[Example 5]
A window film was obtained in the same manner as in Example 1 except that the ultraviolet absorbent in the adhesive layer coating solution was benzotriazole ultraviolet absorbent E (product name: Tinuvin 1130, manufactured by BASF).

[Example 6]
A window film was obtained in the same manner as in Example 1 except that the light transmission part forming composition B having the following composition was used.

<Light transmission part forming composition B>
PO modified bisphenol A diacrylate (product name: BPP-4, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 100 parts by mass Benzophenone photoinitiator (photopolymerization initiator, product name: Irgacure 184, manufactured by Ciba Specialty Chemicals) ) 1 part by mass

[Example 7]
A window film was obtained in the same manner as in Example 1 except that the light control part was replaced with a heat ray absorbing part instead of the low refractive index part. The heat ray absorbing portion was formed according to the following method.
First, a liquid heat ray absorbing part forming composition having the following composition was prepared, and after applying this to the surface including the groove part of the light transmitting part, squeegeeing with an iron doctor blade and filling only into the groove part, Ultraviolet irradiation was performed using a mercury lamp, and the composition for forming a heat ray absorbing portion was crosslinked and cured to form a heat ray absorbing portion. The refractive index of the heat ray absorbing portion was 1.53. The method of measuring the refractive index is the same as the method described in “2. Light control layer”.

<Composition for forming a heat ray absorbing part>
・ Transparent acrylic UV-curable prepolymer (binder resin) consisting of a mixture of urethane acrylate (Daicel Cytec) and dipentaerythritol acrylate oligomer (Shin Nakamura Chemical Co., Ltd.)… 100 parts by mass ・ ATO nanoparticles (average particle) Diameter: 100 nm) 4.5 parts by mass. LaB 0.6 parts by mass. 1-hydroxy-cyclohexyl-phenyl-ketone (photopolymerization initiator, product name: Irgacure 184, manufactured by BASF) 1 part by mass

[Comparative Example 1]
A window film was obtained in the same manner as in Example 1 except that an isocyanate-based crosslinking agent (product name: L-45, manufactured by Soken Chemical Co., Ltd.) was used as the crosslinking agent in the adhesive layer coating solution.

[Comparative Example 2]
A window film was obtained in the same manner as in Example 1 except that the ultraviolet absorbent in the adhesive layer coating solution was cyanoacrylate ultraviolet absorbent F (product name: Biosorb 930, manufactured by Kyodo Pharmaceutical Co., Ltd.).

[Comparative Example 3]
A window film was obtained in the same manner as in Example 1 except that the ultraviolet absorbent in the adhesive layer coating solution was triazine ultraviolet absorbent G (product name: Tinuvin 477 manufactured by BASF).

[Comparative Example 4]
A window film was obtained in the same manner as in Example 1 except that the light transmission part forming composition C having the following composition was used.

<Light transmission part forming composition C>
-Bisphenol A epoxy acrylate (manufactured by DIC) ... 80% by mass
・ Orthophenylphenoxyethyl acrylate: 18% by mass
・ Benzophenone photoinitiator (photopolymerization initiator, product name: Irgacure 184) 2% by mass

[Evaluation]
(UV resistance test)
Each window film of the example and the comparative example was bonded to glass (manufactured by Tokyo Special Glass) having a length of 100 mm, a width of 100 mm, and a thickness of 2.8 mm to prepare a test piece. An ultraviolet deterioration test was performed, and appearance evaluation and holding power evaluation after deterioration were performed.
The ultraviolet degradation resistance test is performed using the following ultra-accelerated ultraviolet degradation resistance tester (manufactured by Iwasaki Electric Co., Ltd., trade name: iSuper UV tester, model number: SUV-W23), and the following (A) to (C): 21 cycles were repeated as one cycle.
(A) Irradiation with ultraviolet rays having an illuminance of 60 mW / cm ² and a peak wavelength of 365 nm is performed for 20 hours in an atmosphere of a temperature of 63 ° C. and a humidity of 50% RH.
(B) Watering treatment by shower is performed for 30 seconds.
(C) Hold in an atmosphere of a temperature of 63 ° C. and a humidity of 98% RH for 4 hours without performing ultraviolet irradiation.

<Appearance evaluation>
A color difference measurement was performed on each test piece after the UV resistance test. The measurement was performed using a spectrophotometer (manufactured by Shimadzu Corporation, model number: UV-3100PC), and the ΔE ^* ab value was measured by the transmission method in accordance with the description of JIS K7105. The ΔE ^* ab value is a color difference formula (ΔE ^* ab = {(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* )) according to the (L ^* , a ^* , b ^* ) space color system of the CIE 1976 standard. ² } ^1/2 ). A ΔE ^* ab value of less than 3 was marked with ◯, and a value of 3 or more was marked with ×. When the ΔE ^* ab value is less than 3, no yellowing of the test piece is confirmed and good weather resistance is exhibited. When the ΔE ^* ab value is 3 or more, the test piece has a practically problematic level. Yellowing was recognized.

<Retention force evaluation>
About each test piece after the UV degradation resistance test, Tensilon (product name: RTG-1205, manufactured by A & D Co., Ltd.) is used and held using a head with a maximum load capacity of 0.5 kN according to JIS A 5759. Force measurements were taken. A holding force of 4N or more was rated as “◯”, and a holding force of less than 4N was marked as “X”. In the test piece having a holding power of less than 4N, peeling was light and a reduction in holding power with respect to glass was confirmed.

  The results of appearance evaluation and holding power evaluation are shown in Table 1.

The light control layer is the same as in Example 1, and the window film using the cross-linking agent other than the metal chelate system in the adhesive layer (Comparative Example 1) was confirmed to be yellowed after the UV resistance test, Moreover, the holding power with respect to glass fell. Similarly, the same tendency was confirmed for the window film (Comparative Examples 2 to 3) using a UV absorber other than the benzotriazole type in the adhesive layer, and a decrease in weather resistance and holding power was confirmed.
Further, the adhesive layer is the same as that of Example 1, and a window film using a polymer of a monomer having a phenyl group other than EO-modified and PO-modified bisphenol A di (meth) acrylate as a material for the light control layer ( Also in Comparative Example 4), yellowing was confirmed after the UV degradation resistance test, and a decrease in holding power against glass was confirmed.

DESCRIPTION OF SYMBOLS 1 ... Adhesive layer 2, 2A, 2B ... Light control layer 10 ... Window film

Claims (1)

Having at least a light control layer and an adhesive layer;
A window film in which the adhesive layer is disposed on the light source side of external light with respect to the light control layer,
The adhesive layer contains an adhesive polymer obtained by crosslinking an acrylic copolymer and a metal chelate crosslinking agent, and a benzotriazole ultraviolet absorber,
The polymer in which the light control layer has at least one of ethylene oxide-modified bisphenol A di (meth) acrylate, propylene oxide-modified bisphenol A di (meth) acrylate, and propoxylated ethoxylated bisphenol A di (meth) acrylate as a constituent unit. Window film characterized by including.