JP6427925B2 - Window film - Google Patents

Description

  The present invention relates to a window film suitably used for automobiles, railways, buildings, and the like, and more particularly to a window film made of a laminated film having ultraviolet reflection characteristics.

  Various window films are used for windows of automobiles, railways, buildings, etc. for the purpose of heat ray cut, ultraviolet ray cut, scattering prevention, exposure prevention and the like (for example, Patent Document 1 and Patent Document 2). In particular, while ultraviolet rays are known to be harmful to the human body, ordinary clear glass cannot cut ultraviolet rays having a wavelength of 350 to 400 nm, so that the ultraviolet rays can be efficiently emitted while being highly transparent and achromatic. There is a growing need for UV-cut films that can cut the skin.

  As such an ultraviolet cut film, a window film containing an ultraviolet absorber in a resin, a window film containing an ultraviolet absorber in an adhesive on a transparent film, and the like are used. However, in the former, since it is necessary to contain a large amount of ultraviolet absorber in the film in order to sufficiently cut the ultraviolet rays only with the ultraviolet absorber, the ultraviolet absorber is placed on the production apparatus due to high heat in the film production process. There is a problem that the quality is deteriorated by precipitation, and the ultraviolet absorber contained in the film bleeds out due to heat when actually used as a window film. In the latter case, there is also a problem that the adhesive layer cannot be thinned because the concentration of the ultraviolet absorber in the adhesive layer cannot be sufficiently increased.

  In addition, because the wavelength of light that can be absorbed by ultraviolet absorbers is limited by the properties of the material, it is not possible to cut light in the ultraviolet region that you want to cut efficiently, or UV absorbers that have high UV-cutting performance are visible light. Since there is also an absorption band in the region, it is slightly colored, so there is a problem that the ultraviolet cut performance cannot be improved in applications where achromatic color is required.

  On the other hand, a polymer multilayer laminated film in which polymers having different refractive indexes are alternately laminated is known as a technique for cutting ultraviolet rays without using an absorbent (for example, Patent Document 3). Although such a polymer multilayer laminated film can selectively select the wavelength to be reflected by controlling the layer thickness, it still has problems in terms of color, ultraviolet cut performance, light resistance and the like.

JP 2008-248131 A Japanese Patent No. 4310312 Japanese National Patent Publication No. 7-507152

  An object of the present invention is to provide a window film that has a high ultraviolet ray cutting performance while having an achromatic color and exhibits good light resistance even during long-term use, in view of the above-described problems of the conventional technology.

  In order to solve the problem, the present invention is intended to provide a window film including the following configuration. Various improved aspects thereof are also provided.

  That is, the present invention is provided with a laminated film in which 51 layers or more of A layers made of thermoplastic resin A and B layers made of thermoplastic resin B are alternately laminated, and an adhesive layer is provided on one surface of the laminated film. Thus, the present invention is a window film that is used by being attached to a window glass and has a maximum reflectance of 50% or more at a wavelength of 350 to 400 nm.

  According to the present invention, it is possible to obtain a window film which has a high UV-cutting performance while being achromatic, and exhibits good light resistance even during long-term use. In addition, when used as a window of an automobile, a train, or a building, ultraviolet rays harmful to the human body can be cut efficiently.

  The embodiments of the present invention will be described in detail below, but the present invention is not construed as being limited to the embodiments including the following examples, and the object of the invention can be achieved and the gist of the invention is described. Of course, various changes can be made without departing from the scope of the invention.

The window film of the present invention is a window film that is used by being laminated on a window glass and having an adhesive layer provided on one side of the laminated film described later and the laminated film.
The laminated film used for the window film of the present invention needs to be made of a thermoplastic resin. Thermoplastic resins are generally cheaper than thermosetting resins and photocurable resins, and can be easily and continuously formed into sheets by known melt extrusion, so that a laminated film can be obtained at low cost. Is possible.

  The laminated film used for the window film of the present invention needs to be formed by alternately laminating 51 layers of the A layer made of the thermoplastic resin A and the B layer made of the thermoplastic resin B. Here, the thermoplastic resin A and the thermoplastic resin B have a refractive index of 0.01 or more different in any of two orthogonal directions arbitrarily selected in the plane of the film and a direction perpendicular to the plane. In addition, the term “alternately laminated” as used herein means that layers made of different thermoplastic resins are laminated in a regular arrangement in the thickness direction. When the layers are made of thermoplastic resins A and B, each layer Are expressed as A layer and B layer, they are stacked as A (BA) n (n is a natural number). By alternately laminating resins with different optical properties in this way, it is possible to express interference reflection that can reflect the light of the designed wavelength from the relationship between the refractive index difference of each layer and the layer thickness. It becomes. Further, when the number of layers to be stacked is 50 or less, high reflectivity cannot be obtained over a sufficient band in the ultraviolet region, and sufficient ultraviolet cut performance cannot be obtained. In addition, the above-described interference reflection can achieve a high reflectance with respect to light in a wider wavelength band as the number of layers increases, and a window film having a high ultraviolet cut performance can be obtained. In addition, although there is no upper limit to the number of layers, as the number of layers increases, the manufacturing cost increases due to the increase in the size of the manufacturing apparatus, the handling properties deteriorate due to the increase in film thickness, and in the process of making laminated glass In reality, about 10,000 layers are practically used.

  The laminated film used for the window film of the present invention is a chain polyolefin such as polyethylene, polypropylene, poly (4-methylpentene-1), polyacetal, and ring-opening metathesis polymerization of norbornene, addition polymerization, and other olefins. Biodegradable polymers such as alicyclic polyolefin, polylactic acid, polybutyl succinate, etc., polyamides such as nylon 6, nylon 11, nylon 12, nylon 66, aramid, polymethyl methacrylate, polyvinyl chloride, Polyvinylidene chloride, polyvinyl alcohol, polyvinyl butyral, ethylene vinyl acetate copolymer, polyacetal, polyglycolic acid, polystyrene, styrene copolymer polymethyl methacrylate, polycarbonate, polypropylene terephthalate Polyester such as polyethylene terephthalate, polybutylene terephthalate, polyethylene-2,6-naphthalate, polyethersulfone, polyetheretherketone, modified polyphenylene ether, polyphenylene sulfide, polyetherimide, polyimide, polyarylate, tetrafluoroethylene resin A trifluorinated ethylene resin, a trifluorinated ethylene resin, a tetrafluoroethylene-6 fluoropropylene copolymer, polyvinylidene fluoride, or the like can be used. Of these, polyester is particularly preferred from the viewpoint of strength, heat resistance, transparency and versatility. These may be a copolymer or a mixture of two or more kinds of resins.

  The polyester is preferably a polyester obtained by polymerization from a monomer mainly composed of an aromatic dicarboxylic acid or an aliphatic dicarboxylic acid and a diol. Here, as the aromatic dicarboxylic acid, for example, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyl Examples include dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenylsulfone dicarboxylic acid, and the like. Examples of the aliphatic dicarboxylic acid include adipic acid, suberic acid, sebacic acid, dimer acid, dodecanedioic acid, cyclohexanedicarboxylic acid and ester derivatives thereof. Of these, terephthalic acid and 2,6 naphthalenedicarboxylic acid exhibiting a high refractive index are preferable. These acid components may be used alone or in combination of two or more thereof, and further may be partially copolymerized with oxyacids such as hydroxybenzoic acid.

  Examples of the diol component include ethylene glycol, 1,2-propanediol, 1,3-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, and 1,5-pentanediol. 1,6-hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2-bis (4- Hydroxyethoxyphenyl) propane, isosorbate, spiroglycol and the like. Of these, ethylene glycol is preferably used. These diol components may be used alone or in combination of two or more.

  In the laminated film used for the window film of the present invention, the thermoplastic resin is, for example, polyethylene terephthalate and a polymer thereof, polyethylene naphthalate and a copolymer thereof, polybutylene terephthalate and a copolymer thereof among the polyesters, It is preferable to use polybutylene naphthalate and its copolymer, further polyhexamethylene terephthalate and its copolymer, polyhexamethylene naphthalate and its copolymer, and the like.

  In the laminated film used for the window film of the present invention, the difference in in-plane average refractive index between the A layer made of the thermoplastic resin A and the B layer made of the thermoplastic resin B is preferably 0.03 or more. More preferably, it is 0.05 or more, More preferably, it is 0.1 or more. When the difference in in-plane average refractive index is smaller than 0.03, sufficient reflectivity cannot be obtained, and the ultraviolet ray cutting performance may be insufficient. As an achievement method, the thermoplastic resin A is crystalline, and the thermoplastic resin B is amorphous. In this case, a refractive index difference can be easily provided in the stretching and heat treatment steps in the production of the laminated film.

  In the laminated film used for the window film of the present invention, as a preferred combination of the thermoplastic resin A and the thermoplastic resin B, the absolute value of the difference in SP value of each thermoplastic resin is 1.0 or less. Firstly preferred. When the absolute value of the difference in SP value is 1.0 or less, delamination hardly occurs. More preferably, the thermoplastic resin A and the thermoplastic resin B are preferably made of a combination provided with the same basic skeleton. Here, the basic skeleton is a repeating unit constituting the resin. For example, when polyethylene terephthalate is used as the thermoplastic resin A, the thermoplastic resin B is easy to realize a highly accurate laminated structure. It is preferable to include ethylene terephthalate which is the same basic skeleton as polyethylene terephthalate. When the thermoplastic resin A and the thermoplastic resin B are resins containing the same basic skeleton, the lamination accuracy is high and delamination at the lamination interface is less likely to occur.

  In the laminated film used for the window film of the present invention, a preferable combination of the thermoplastic resin A and the thermoplastic resin B is a combination of thermoplastic resins in which a difference in glass transition temperature between the thermoplastic resins is 20 ° C. or less. . If the difference in glass transition temperature is greater than 20 ° C., the thickness uniformity when forming a laminated film becomes poor, resulting in uneven UV-cutting performance, It may cause wrinkles. It is also preferable that the thermoplastic resin A is crystalline and the thermoplastic resin B is amorphous, and the glass transition temperature of the thermoplastic resin A is lower than the glass transition temperature of the thermoplastic resin B. In this case, the orientation of the amorphous resin can be suppressed when compared with the crystalline resin, and the refractive index can be easily adjusted when the laminated resin is stretched at an appropriate stretching temperature to orient and crystallize the crystalline resin. A difference can be provided.

  As an example of a combination of thermoplastic resins for satisfying the above conditions, in the laminated film used for the window film of the present invention, the thermoplastic resin A comprises polyethylene terephthalate or polyethylene naphthalate, and the thermoplastic resin B is A polyester comprising a spiroglycol-derived polyester is preferred. The polyester derived from spiroglycol is a polyester using spiroglycol as a diol component, a copolymer with other ester structural units, a polyester using spiroglycol as a single diol component, or other polyesters. A polyester blended with a polyester resin and preferably having a spiroglycol residue occupying more than half of all diol residues in the polyester resin. Spiroglycol-derived polyester is preferable because it has a small glass transition temperature difference from polyethylene terephthalate or polyethylene naphthalate, and thus is not easily stretched during film formation and is also difficult to delaminate. More preferably, the thermoplastic resin A comprises polyethylene terephthalate or polyethylene naphthalate, and the thermoplastic resin B is preferably a polyester using spiroglycol and cyclohexanedicarboxylic acid. When the polyester is obtained using spiroglycol and cyclohexanedicarboxylic acid, the difference in the in-plane refractive index from polyethylene terephthalate or polyethylene naphthalate is increased, so that high reflectance is easily obtained. Moreover, since the glass transition temperature difference with polyethylene terephthalate or polyethylene naphthalate is small and the adhesiveness is excellent, it is difficult to be over-stretched during film formation, and is also difficult to delaminate.

  Moreover, in the laminated film used for the window film of the present invention, it is also preferred that the thermoplastic resin A comprises polyethylene terephthalate or polyethylene naphthalate, and the thermoplastic resin B is a polyester derived from cyclohexanedimethanol. The polyester derived from cyclohexanedimethanol is a polyester using cyclohexanedimethanol as a diol component, a copolymer with another ester structural unit, a polyester using cyclohexanedimethanol as a single diol component, or those Is blended with other polyester resins, and preferably refers to a polyester in which cyclohexanedimethanol residues occupy more than half of all diol residues in the polyester resin. Polyester derived from cyclohexanedimethanol is preferable because it has a small glass transition temperature difference from polyethylene terephthalate or polyethylene naphthalate, and thus is less likely to be over-stretched during molding and is also difficult to delaminate. More preferably, at least one thermoplastic resin is an ethylene terephthalate polycondensate having a copolymerization amount of cyclohexanedimethanol of 15 mol% or more and 60 mol% or less. In this way, while having high reflection performance, the change in optical characteristics due to heating and aging is particularly small, and peeling between layers is less likely to occur. An ethylene terephthalate polycondensate having a copolymerization amount of cyclohexanedimethanol of 15 mol% or more and 60 mol% or less adheres very strongly to polyethylene terephthalate. In addition, the cyclohexanedimethanol group has a cis or trans isomer as a geometric isomer, and a chair type or a boat type as a conformational isomer. In addition, the change in optical characteristics due to thermal history is even less, and blurring during film formation hardly occurs.

  In the window film of the present invention, the maximum reflectance at a wavelength of 350 to 400 nm needs to be 50% or more. Here, the reflectance is the reflectance of reflected light when white light is incident at an incident angle of 12 °. Further, the white light here is light that has a continuous intensity distribution in a wide range of visible light region and can be recognized as an achromatic color, such as sunlight or a halogen lamp. When the maximum reflectance at a wavelength of 350 to 400 nm is less than 50%, the ultraviolet ray cutting performance is not sufficient, and it is not suitable for window films used for automobiles, railways, and building windows that require high ultraviolet ray cutting performance. . Preferably, the maximum reflectance at a wavelength of 350 to 400 nm is 80% or more, and more preferably, the maximum reflectance at a wavelength of 350 to 400 nm is 90% or more. As the maximum reflectance at a wavelength of 350 to 400 nm increases, it becomes possible to provide a high UV-cutting performance. Particularly, when the average reflectance at a wavelength of 350 to 400 nm is 70% or more, most of UV rays are cut off. It becomes possible to do. In order to obtain a window film having a maximum reflectance of 50% or more at a wavelength of 350 to 400 nm, it can be achieved by increasing the number of layers of the laminated film or the refractive index difference of the thermoplastic resin laminated alternately. It is. Although it depends on the refractive index difference of the alternately laminated thermoplastic resins, for example, as a preferable number of layers, the total number of the two or more types of thermoplastic resins is 51 or more, and maximum reflection at a wavelength of 350 to 400 nm. It becomes easy for the rate to be 50% or more. Further, when the maximum reflectance at a wavelength of 350 to 400 nm is 70% or more, it is preferably 100 layers or more, and for the average reflectance at a wavelength of 350 to 400 nm to be 70% or more, it is 100 layers or more. And it is preferable that the layer thickness of B layer which consists of A layer which consists of adjacent thermoplastic resin A and B which consists of thermoplastic resin B shall be 100-130 nm. The window film of the present invention is used by being attached to glass. However, since general clear glass can cut only ultraviolet rays having a wavelength of 300 nm or less, the window film can reflect ultraviolet rays having a wavelength of 300 nm or more. desirable. Therefore, in the window film of the present invention, it is also preferable that the average reflectance at a wavelength of 300 to 400 nm is 70% or more. In this case, when pasted on glass and used as a window film, almost all ultraviolet rays can be cut.

In the window film of the present invention, the maximum value of transmittance at a wavelength of 300 to 380 nm is preferably 30% or less. When the maximum value of transmittance at a wavelength of 300 to 380 nm is 30% or less, ultraviolet rays harmful to the human body can be cut. More preferably,
The maximum value of the transmittance at a wavelength of 300 to 380 nm is 10% or less, and in this case, the ultraviolet rays can be almost cut off. In order to obtain such a window film, it is desirable that the minimum reflectance of the laminated film of the present invention at a wavelength of 350 to 380 nm is 70% or more. Further, when the longest absorption wavelength of each thermoplastic resin constituting the laminated film used for the window film of the present invention is λAbs (nm), the minimum reflectance at a wavelength λAbs to 380 nm is more preferably 70% or more. . In this case, when used by being attached to glass, the ultraviolet rays can be substantially cut off, which is suitable as a window film. The longest absorption wavelength λAbs of the thermoplastic resin here is the longest wavelength at which the difference between the transmittance and the reflectance of the window film is 10% or more.

  In the window film of this invention, it is preferable that the saturation of the transmitted light in C light source is 3 or less. The C light source here is defined in JIS Z 8701, and is substantially calculated based on JIS Z8722 from the transmittance of each wavelength measured by various spectrophotometers. . In this case, even when a window film is attached to the window, the color can be suitably used without causing a problem. In order to set the saturation of transmitted light in the C light source to 3 or less, the transmittance at a wavelength of 420 nm can be achieved by 80% or more. In order to set the transmittance of the window film at a wavelength of 420 nm to 80% or more, in the window film of the present invention, the reflectance at a wavelength of 420 nm is preferably 20% or less. In this case, it becomes easy to set the transmittance at a wavelength of 420 nm to 80% or more.

  On the other hand, in order to achieve high ultraviolet cut performance, in the window film of the present invention, the reflectance at a wavelength of 380 nm is preferably 70% or more. More preferably, the reflectance at a wavelength of 400 nm is 70% or more. Since the intensity of sunlight increases as the wavelength increases, it becomes easier to obtain the effect of cutting off ultraviolet light when higher wavelength light can be cut. More preferably, the reflectance at a wavelength of 380 nm is 70% or more, and the reflectance at a wavelength of 420 nm is 20% or less. In this case, it can be used as a window film with an achromatic color while maintaining high UV-cut performance. Here, when a general ultraviolet absorber is used, the absorption characteristic depends on the characteristic of the ultraviolet absorber, so that the steep transmittance cannot be changed or the absorption band cannot be freely selected. In this case, there is a problem that the transmittance at a wavelength of 300 to 380 nm cannot be reduced uniformly. On the other hand, if it is a polymer multilayer laminated film in which the thermoplastic resins A and B are alternately laminated like the window film of the present invention, light having a wavelength of 300 to 400 nm can be cut uniformly by controlling the layer thickness. This makes it easy to provide a sharp change in transmittance. Preferably, the layer thickness of the majority of the layers from N / 4 to 3N / 4 on the adhesive layer side is 50 nm or more with respect to the total number N of layers of the laminated film. In order to realize the steep rise of reflection as described above, a preferable mode is to continuously provide layers having substantially the same thickness as the layer distribution for reflecting light having a wavelength of around 400 nm. In this way, it is possible to realize a steep rise without increasing the reflection while broadening the reflectance. Here, when the laminated film is formed, the layer near the surface of the film is affected by the polymer flow. For example, the layer for reflecting the light near the wavelength of 400 nm in the vicinity of the surface layer should have almost the same layer thickness. Even if the laminating apparatus is designed, the layer thickness distribution tends to be widened by thinning the film, etc. Therefore, the layers from N / 4 to 3N / 4 layers on the adhesive layer side with respect to the total number N of laminated films By providing a layer having a thickness of 50 nm or more capable of reflecting light in the vicinity of a wavelength of 400 nm, the layer can be laminated with high accuracy without being affected by the polymer flow, and the reflectance at a wavelength of 380 nm can be increased. It becomes easy to set the reflectance at a wavelength of 420 nm to 20% or less while keeping it to 70% or more.

In the window film of the present invention, the elongation retention when irradiated with a halogen lamp at 100 mW / cm ² for 12 hours is preferably 50% or more. The window film can cut off ultraviolet rays that are harmful to humans by suppressing the transmission of ultraviolet rays that pass through the film, but the film itself deteriorates due to ultraviolet rays, so it becomes fragile and partially drowns. It may cause cracking. Here, in the window film of the present invention, since the ultraviolet rays are reflected in the laminated film, the amount of the ultraviolet rays absorbed by the film itself can be cut, and the deterioration of the film is suppressed by the ultraviolet rays. As a result, the elongation retention of the film can be set to 50% or more. Therefore, even when the film is actually used as a window film, it becomes easy to suppress peeling or cracking due to deterioration of the film.

In the laminated film used for the window film of the present invention, the layer thickness of the majority of the layers from the surface layer on the adhesive layer side to the N / 4th layer with respect to the total number N of laminated films is 50 nm or less. Is preferred. As described above, the laminated film of the present invention can cut ultraviolet rays when viewed as a film, but ultraviolet rays are reflected at the interface between layers designed to correspond to the wavelength of light. The thermoplastic resin constituting the laminated film is gradually deteriorated by passing ultraviolet rays. Moreover, since the window film of this invention is normally affixed and used from the adhesion layer side inside the window of a motor vehicle, a railway, and a building, an ultraviolet-ray is incident from the adhesion layer side. Here, generally used clear glass absorbs light having a wavelength of 300 nm or less. Moreover, the thermoplastic resin used for the window film absorbs ultraviolet rays having a wavelength of 350 nm or less. Here, the present inventors have found that the film is deteriorated by ultraviolet rays having a wavelength of 300 to 350 nm that cannot be cut with glass, and suppressing the deterioration of the film by reflecting the ultraviolet rays having a wavelength of 300 to 350 nm as much as possible on the film surface. The present inventors have found that the elongation retention rate when irradiated with a halogen lamp at 100 mW / cm ² for 12 hours can be 50% or more. That is, when the layer thickness of the majority of the layers from the surface layer on the pressure-sensitive adhesive layer side to the N / 4th layer is 50 nm or less with respect to the total number N of laminated films, the layer with a thickness of 50 nm or less has a wavelength of 300 The layer thickness is suitable for reflecting ~ 350nm ultraviolet rays, and the ultraviolet rays incident from the adhesive layer side can be reflected before entering the inner layer of the film, so that the thermoplastic resin constituting the film is deteriorated by ultraviolet rays. It can be suppressed. More preferably, the layer thickness of all layers except the outermost layer among the layers from the surface layer on the adhesive layer side to the N / 4th layer with respect to the total number N of layers of the laminated film is 50 nm or less. In this case, ultraviolet rays that cause deterioration of the thermoplastic resin in the vicinity of the surface layer can be cut more efficiently.

Furthermore, in the window film of the present invention, both surface layers of the laminated film are made of the thermoplastic resin A, the thermoplastic resin B contains an ultraviolet absorber, and the laminated film transmits light at a wavelength of 420 nm. It is also preferable that the rate is 50% or more. By containing an ultraviolet absorber, it is possible to suppress the ultraviolet rays that cause film deterioration from entering the laminated film, so that the elongation retention rate when irradiated with a halogen lamp at 100 mW / cm ² for 12 hours. It becomes easy to improve. On the other hand, depending on the type of UV absorber to be added, by adding the UV absorber to the laminated film, it can be post-processed during the production of the laminated film or when it is used as a window film afterwards, and actually attached to glass In doing so, the UV absorber may be deposited from the surface of the laminated film or from the production apparatus. In response to this problem, the present inventors made both surface layers of the laminated film A layer made of thermoplastic resin A, and added an ultraviolet absorber only to B layer made of thermoplastic resin B that is not exposed on the surface of the laminated film. By doing this, it discovered that precipitation of the ultraviolet absorber can be suppressed from a laminated film or a manufacturing apparatus. Preferably, the thermoplastic resin A is a crystalline resin, more preferably a crystalline polyester. Use of the crystalline resin for the A layer has an effect of suppressing the crystallization of the resin during the production of the film and the precipitation of the ultraviolet absorber. Moreover, when the transmittance | permeability in wavelength 420nm of a laminated | multilayer film is 50% or more, when it is set as a window film, coloring is suppressed and it becomes possible to use it suitably. Preferably, the transmittance at a wavelength of 420 nm is 80% or more, and in this case, an almost achromatic film can be obtained.

  In the window film of this invention, it is also preferable to comprise 50 or more layers with a layer thickness of 150 to 200 nm of the laminated film. By setting the layer thickness to 150 to 200 nm, it becomes possible to reflect light in the near infrared region with a wavelength of 900 to 1200 nm, and it is possible to provide heat ray cutting performance in addition to ultraviolet cut, so as a window film This is preferable.

  In the window film of the present invention, the haze is preferably 1.5% or less. In this case, it is a window film that can be suitably used even in applications where transparency is high and particularly high safety is required, such as automobile and railway windows. Moreover, haze here means the haze at the time of bonding the clear glass and window film whose haze in glass independent is 1.0% or less, and the adhesion layer side. More preferably, the haze is 1.0% or less. In this case, since the transparency is the same as that of the glass before the window film is pasted, there is no problem in safety. The window film of the present invention cuts ultraviolet rays with a structure in which two types of thermoplastic resins are alternately laminated without using an ultraviolet absorber, so that ultraviolet rays are used when the ultraviolet absorber is used under agglomeration or high temperature / high humidity conditions. Since no increase in haze caused by bleeding out of the absorbent or the like occurs, it becomes easy to set the haze to 1.5% or less.

  Next, a preferred method for producing a laminated film used for the window film of the present invention will be described below by taking a laminated film made of thermoplastic resins A and B as an example. Of course, the present invention should not be construed as being limited to such examples. Moreover, the laminated structure of the laminated film used in the present invention can be easily realized by the same method as described in the paragraphs [0053] to [0063] of JP-A-2007-307893.

  A thermoplastic resin is prepared in the form of pellets. The pellets are dried in hot air or under vacuum as necessary, and then supplied to a separate extruder. When the laminated film contains an ultraviolet absorber, pellets prepared by kneading the ultraviolet absorber in a thermoplastic resin in advance are prepared, or the thermoplastic resin and the ultraviolet absorber are kneaded in an extruder. In the extruder, the resin melted by heating to a temperature equal to or higher than the melting point is made uniform in the amount of resin extruded by a gear pump or the like, and foreign matter or denatured resin is removed through a filter or the like. These resins are formed into a desired shape by a die and then discharged. And the sheet | seat laminated | stacked in the multilayer discharged | emitted from die | dye is extruded on cooling bodies, such as a casting drum, and is cooled and solidified, and a casting film is obtained. At this time, it is preferable to use a wire-like, tape-like, needle-like, or knife-like electrode to be brought into close contact with a cooling body such as a casting drum by an electrostatic force and rapidly solidify. Also preferred is a method in which air is blown out from a slit-like, spot-like, or planar device to be brought into close contact with a cooling body such as a casting drum and rapidly cooled and solidified, or brought into close contact with a cooling body with a nip roll and rapidly cooled and solidified.

  Further, a plurality of resins of the thermoplastic resin used for the A layer and a different thermoplastic resin B are sent out from different flow paths using two or more extruders, and are sent into the multilayer laminating apparatus. As the multilayer laminating apparatus, a multi-manifold die, a feed block, a static mixer, or the like can be used. In particular, in order to efficiently obtain the configuration of the present invention, a feed block having 51 or more fine slits should be used. Is preferred. When such a feed block is used, since the apparatus does not become extremely large, there is little foreign matter due to thermal degradation, and high-precision lamination is possible even when the number of laminations is extremely large. Also, the stacking accuracy in the width direction is significantly improved as compared with the prior art. Moreover, in this apparatus, since the thickness of each layer can be adjusted with the shape (length, width) of a slit, it becomes possible to achieve arbitrary layer thickness.

  The molten multilayer laminate formed in the desired layer structure in this way is led to a die, and a casting film is obtained in the same manner as described above.

  The casting film thus obtained is preferably biaxially stretched. Here, biaxial stretching refers to stretching in the longitudinal direction and the width direction. Stretching may be performed sequentially in two directions or simultaneously in two directions. Further, re-stretching may be performed in the longitudinal direction and / or the width direction.

  First, the case of sequential biaxial stretching will be described. Here, stretching in the longitudinal direction refers to stretching for imparting molecular orientation in the longitudinal direction to the film, and is usually performed by a difference in peripheral speed of the roll, and this stretching may be performed in one step. Alternatively, a plurality of roll pairs may be used in multiple stages. Although it changes with kinds of resin as a magnification of extending | stretching, 2 to 15 times is preferable normally, and when polyethylene terephthalate is used for either of the resin which comprises a laminated | multilayer film, 2 to 7 times are used especially preferably. Moreover, as extending | stretching temperature, the glass transition temperature-glass transition temperature +100 degreeC of resin which comprises a laminated | multilayer film are preferable.

  The uniaxially stretched film thus obtained is subjected to surface treatment such as corona treatment, flame treatment, and plasma treatment as necessary, and then functions such as slipperiness, easy adhesion, and antistatic properties are provided. It may be applied by in-line coating.

  Subsequently, stretching in the width direction refers to stretching for imparting the orientation in the width direction to the film. Usually, the film is stretched in the width direction using a tenter while being conveyed while holding both ends of the film with clips. Although it changes with kinds of resin as a magnification of extending | stretching, 2 to 15 times is preferable normally, and when polyethylene terephthalate is used for either of the resin which comprises a laminated | multilayer film, 2 to 7 times are used especially preferably. Moreover, as extending | stretching temperature, the glass transition temperature-glass transition temperature +120 degreeC of resin which comprises a laminated | multilayer film are preferable.

  The biaxially stretched film is preferably subjected to a heat treatment at a temperature not lower than the stretching temperature and not higher than the melting point in the tenter in order to impart flatness and dimensional stability. By performing the heat treatment, the dimensional stability of the molding film is improved. After being heat-treated in this way, it is gradually cooled down uniformly, then cooled to room temperature and wound up. Moreover, you may use a relaxation process etc. together in the case of annealing from heat processing as needed.

  Next, the case of simultaneous biaxial stretching will be described. In the case of simultaneous biaxial stretching, the resulting cast film is subjected to surface treatment such as corona treatment, flame treatment, and plasma treatment as necessary, and then, such as slipperiness, easy adhesion, antistatic properties, etc. The function may be imparted by in-line coating.

  Next, the cast film is guided to a simultaneous biaxial tenter, and conveyed while holding both ends of the film with clips, and stretched in the longitudinal direction and the width direction simultaneously and / or stepwise. As simultaneous biaxial stretching machines, there are pantograph method, screw method, drive motor method, linear motor method, but it is possible to change the stretching ratio arbitrarily and drive motor method that can perform relaxation treatment at any place or A linear motor system is preferred. Although the stretching magnification varies depending on the type of resin, it is usually preferably 6 to 50 times as the area magnification. When polyethylene terephthalate is used as one of the resins constituting the laminated film, the area magnification is 8 to 30 times. Is particularly preferably used. In particular, in the case of simultaneous biaxial stretching, it is preferable to make the stretching ratios in the longitudinal direction and the width direction the same and to make the stretching speeds substantially equal in order to suppress the in-plane orientation difference. Moreover, as extending | stretching temperature, the glass transition temperature-glass transition temperature +120 degreeC of resin which comprises a laminated | multilayer film are preferable.

  The film thus biaxially stretched is preferably subsequently subjected to a heat treatment not less than the stretching temperature and not more than the melting point in the tenter in order to impart flatness and dimensional stability. In this heat treatment, in order to suppress the distribution of the main orientation axis in the width direction, it is preferable to perform relaxation treatment in the longitudinal direction instantaneously immediately before and / or immediately after entering the heat treatment zone. After being heat-treated in this way, it is gradually cooled down uniformly, then cooled to room temperature and wound up. Moreover, you may perform a relaxation | loosening process in a longitudinal direction and / or the width direction at the time of annealing from heat processing as needed. Immediately before and / or immediately after entering the heat treatment zone, a relaxation treatment is performed in the longitudinal direction.

  In the window film of the present invention, an adhesive layer needs to be provided on one surface of the laminated film. Since the use of the present invention is affixed to a window made of glass of an automobile, a railway or a building, it can be easily attached to the window by providing an adhesive layer.

  As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer of the laminated film of the present invention, a rubber pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, a cross-linked acrylic pressure-sensitive adhesive, a vinyl pressure-sensitive adhesive, a silicone pressure-sensitive adhesive and the like are preferable. More preferably, it is an acrylic adhesive. More preferably, it is a crosslinkable acrylic pressure-sensitive adhesive. If necessary, a carboxylic acid compound, an isocyanate compound, a melamine compound, or a metal compound may be added to these pressure-sensitive adhesives as long as the properties are not impaired. Acrylic adhesives are excellent in terms of light resistance, weather resistance, oil resistance and the like, and are particularly suitable when used as window films.

  In the window film of the present invention, it is preferable that a hard coat layer is further provided on the opposite side of the adhesive layer of the laminated film. In this case, it is possible to prevent the visibility from being deteriorated when affixed to a window of an automobile, a railway or a building. Resins that form the hard coat layer include oligomers such as acryloyl group-containing polyester resins, acrylic resins, urethane resins, and other radically polymerizable compounds such as prepolymers and monomers, as well as epoxy rings, oxetane rings, vinyl ether groups, and the like. And cationically polymerizable compounds such as prepolymers and monomers. These resins are crosslinked by applying energy such as heat, ultraviolet rays and electron beams.

  Preferred resins for forming the hard coat layer are those that are difficult to curl and have good adhesion to the substrate, and include low-shrinkage urethane acrylate and epoxy compounds. Specific examples of urethane acrylate include AT-600, UA-1011, UF-8001, UF-8003, etc. manufactured by Kyoeisha Chemical Co., Ltd., UV7550B, UV-7600B, etc. manufactured by Nippon Synthetic Chemical Co., Ltd. -2PPA, UA-NDP, etc., such as Ebecryl-270, Ebecryl-284, Ebecryl-264, Ebecryl-9260, etc. manufactured by Daicel UCB, or an epoxy compound, specifically, EHPE3150, GT300 manufactured by Daicel Chemical Industries, Ltd. , GT400, Celoxide 2021, etc., EX-321, EX-411, EX-622, etc. manufactured by Nagase Chemtech. However, it is not limited to this. Of urethane acrylates that can achieve higher hardness, urethane acrylate oligomers and monomers can be obtained by reacting polyhydric alcohols, polyvalent isocyanates, and hydroxyl group-containing acrylates. Specifically, Kyoeisha Chemical Co., Ltd. UA-306H, UA-306T, UA-306l, etc., Nippon Synthetic Chemical Co., Ltd. UV-1700B, UV-6300B, UV-7600B, UV-7605B, UV-7640B, UV -7650B, etc., U-4HA, U-6HA, UA-100H, U-6LPA, U-15HA, UA-32P, U-324A, etc., manufactured by Shin-Nakamura Chemical Co., Ltd., Ebecryl-1290, Ebecryl manufactured by Daicel UCB -1290K, Ebecryl-5129 and the like, UN-3220HA, UN-3220HB, UN-3220HC, UN-3220HS and the like manufactured by Negami Kogyo Co., Ltd. can be exemplified. However, it is not limited to this. The radical polymerizable compound and the cationic polymerizable compound may be used alone or in combination of two or more.

  In addition, when using a resin that crosslinks by ultraviolet irradiation, acetophenones, benzophenones, α-hydroxyketones, benzylmethylketals, α-aminoketones, bisacylphosphine oxides, etc. are used as photo radical polymerization initiators. Used alone or in combination. Specific examples include Irgacure 184, Irgacure 651, Darocur 1173, Irgacure 907, Irgacure 369, Irgacure 819, Darocur TPO and the like manufactured by Ciba Specialty Chemicals. The photo cationic polymerization initiator is not particularly limited as long as it generates a cationic polymerization catalyst such as a Lewis acid by ultraviolet irradiation. For example, an onium salt such as a diazonium salt, an iodonium salt, or a sulfonium salt can be used. Specifically, aryldiazonium hexafluoroantimonate, aryldiazonium hexafluorophosphate, aryldiazonium tetrafluoroborate, diaryliodonium hexafluoroantimonate, diaryliodonium hexafluorophosphate, diaryliodonium tetrafluoroborate, triarylsulfonium hexa Examples include fluoroantimonate, triarylsulfonium hexafluorophosphate, and triarylsulfonium tetrafluoroborate. These may be used alone or in combination of two or more.

  Specifically, a commercially available photocationic initiator may be used as the photocationic polymerization initiator. For example, UVI-6990 made by Union Carbide, UVI-6990 made by Dow Chemical Japan, Uvacure 1591 made by Daicel UCB, Adeka optomer SP-150, Adeka optomer SP-170 made by Asahi Denka, Midori Chemical Co., Ltd. DPI-101, DPI-105, MPI-103, MPI-105, BBI-101, BBI-103, BBI-105, TPS-102, TPS-103, TPS-105, MDS-103, MDS-105 manufactured by Examples include DTS-102, DTS-103, Irgacure 250 manufactured by Ciba Specialty Chemicals.

  The isocyanates used in the present invention have two or more isocyanate groups in the molecule, for example, diisocyanates include hexamethylene diisocyanate, diphenylmethane diisocyanate, xylylene diisocyanate, isophorone diisocyanate, phenylene diisocyanate, tolylene diisocyanate, trimethylhexa Methylene diisocyanate, naphthalene diisocyanate, diphenyl ether diisocyanate, diphenylpropane diisocyanate, biphenyl diisocyanate, and their isomers, alkyl-substituted products, halides, hydrogenated products to the benzene ring, and the like can be used. Furthermore, triisocyanates having 3 isocyanate groups, tetraisocyanates having 4 isocyanate groups, and the like can be used, and these can be used in combination. Among these, aromatic polyisocyanates are preferable from the viewpoint of heat resistance, and aliphatic polyisocyanates or alicyclic polyisocyanates are preferable from the viewpoint of preventing coloring. Examples of commercially available isocyanate prepolymers include, for example, Death Module E3265, E4280, TPLS2010 / 1, E1160, E1240, E1361, E14, E15, E25, E2680, Sumidur E41, E22, manufactured by Sumika Bayer Urethane Co., Ltd. Examples include Duranate D-101 and D-201 manufactured by KK.

  Suitable organic solvents for use in the present invention include methyl acetate, ethyl acetate, propyl acetate, butyl acetate, xylene, methyl ethyl ketone, methyl isobutyl ketone, ethylene glycol monoethyl ether acetate, propylene glycol monomethyl ether acetate, and the like. These several types may be mixed and used. These solvents can be present in the composition in an amount up to 95% by weight of the total composition. These solvents are substantially removed when the solution is applied to the transparent substrate and dried. Furthermore, monofunctional monomers such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and glycidyl (meth) acrylate, preferably 10% by weight or less based on the solid content, can be used as a diluent. . Furthermore, examples of the diluent for the cationic polymerization compound include Celoxide 3000 and Celoxide 2000 manufactured by Daicel Chemical Industries.

  In the window film of the present invention, it is also preferable that the adhesive layer or / and the hard coat layer further contains an ultraviolet absorber, and the transmittance of the layer containing the ultraviolet absorber is 400% or more at a wavelength of 400 nm. . As described above, in the window film of the present invention, ultraviolet rays are cut by reflecting the ultraviolet rays with the laminated film, but the ultraviolet ray cutting performance may be insufficient depending on the use or the case. At this time, in addition to being able to obtain a high-quality UV cut film substantially free of UV transmission by absorbing UV light with a very small amount of UV absorber in the adhesive layer or hard coat layer, There is also an effect of suppressing deterioration of the laminated film by ultraviolet rays. Further, the transmittance of the layer containing the ultraviolet absorber at a wavelength of 400 nm is 80% or more, so that the laminated film maintains the characteristics of reflecting ultraviolet rays on the high wavelength side having a wavelength of 400 nm while being achromatic. On the other hand, the ultraviolet cut performance can be further improved. Preferably, an ultraviolet absorber is contained in the adhesive layer. In this case, an effect of suppressing deterioration of the laminated film due to ultraviolet rays can be expected. In any case, the effect can be obtained with a very small amount of UV absorber compared to the case of obtaining a window film having UV-cutting performance with only an UV absorber. It becomes possible to make a high-quality window film without problems.

  Examples of the ultraviolet ray absorber include benzophenone compounds and benzotriazole compounds, and specific examples include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5 Sulfonic acid trihydrate, 2-hydroxy-4-octyloxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2,2′4,4′-tetrahydroxybenzophenone, 2,2 '-Dihydroxy-4,4'-dimethoxybenzophenone, 1,4-bis (4-benzoyl-3-hydroxyphenoxy) -butane, 2- (2-hydroxy-5-methylphenyl) -2H-benzotriazole, 2- (2-hydroxy 5-t-octylphenyl) -2H-benzotriazole, 2- (3-t-butyl-2-hydroxy-5-methylphenyl) -5-chloro-2H-benzotriazole, 2- (3,5-di- t-phenyl-2-hydroxyphenyl) -2H-benzotriazole, 2- (2H-benzotriazol-2-yl) -4-methyl-6- (3,4,5,6-tetrahydrophthalimidylmethyl) phenol 2- (2-hydroxy-4-octyloxyphenyl) -2H-benzotriazole, 2,4-di-t-butyl-6- (5-chlorobenzotriazol-2-yl) phenol, 2- (3- Dodecyl-2-hydroxy-5-methylphenyl) -2H-benzotriazole, 2- (2H-benzotriazol-2-yl) -4,6-bis (1- Chill-1-phenylethyl) phenol, 2,2'-methylenebis (6- (2H-benzotriazol-2-yl) -4-1,1,3,3- tetramethylbutyl) phenol), and the like.

  In particular, in the window film of the present invention, it is preferable that the ultraviolet absorber is a triazine compound satisfying the following formula (1), and the melting point of the triazine compound is 120 ° C. or higher (R is C2-10). Alkyl group). In the case of the triazine compound represented by the following formula (1), ultraviolet rays up to a wavelength of around 400 nm can be cut over a wide wavelength band, while having a high transparency at a wavelength of 420 nm. It is possible to achieve both high UV-cutting performance, transparency and achromatic color. In addition, the triazine compound represented by the following formula (1) is also characterized by having a high melting point due to its structure. Further, by selecting a substituent and setting the melting point to 120 ° C. or higher, practical processing / It has been found that the triazine compound is effective for suppressing precipitation on the film surface, deterioration of the triazine compound itself, etc. without melting the triazine compound at the use temperature (˜100 ° C.).

The method of providing the adhesive layer or the hard coat layer is not limited, but known printing methods such as gravure printing method, screen printing method, offset printing method, known gravure coater, gravure reverse coater, lip coater, flexo coater, blanket coater. Coating on the resin film as the base material with coating methods such as roll coater, knife coater, air knife coater, kiss touch coater, kiss touch reverse coater, comma coater, comma reverse coater, micro reverse coater, etc. It can be formed by heat drying for solidification or by irradiation with light such as ultraviolet rays or electron beams as necessary. Moreover, it is also preferable to temporarily attach a protective film on the adhesive layer following the drying step.

  The window film of the present invention can be suitably used for ultraviolet blocking of buildings and automobile windows by bonding to a transparent substrate such as glass.

  Furthermore, in a window glass of a building, a pair glass in which two opposing glasses are provided with a space of at least 0.1 mm or more mainly for heat insulation is widely used. It is also preferable to attach the glass. In this case, in addition to the heat insulating effect of the pair glass, a function of cutting off ultraviolet rays can be imparted. Moreover, since this film shows the outstanding light resistance as above-mentioned, it can use especially preferably in the pair glass which cannot change the film easily.

Hereinafter, it demonstrates using the Example of the laminated | multilayer film of this invention.
[Methods for measuring physical properties and methods for evaluating effects]
The characteristic value evaluation method and the effect evaluation method are as follows.

(1) Layer thickness, number of layers, layered structure The layer structure of the film was determined by observation with a transmission electron microscope (TEM) for a sample obtained by cutting a cross section using a microtome. That is, using a transmission electron microscope H-7100FA type (manufactured by Hitachi, Ltd.), the cross section of the film was magnified 10000 to 40000 times under the condition of an acceleration voltage of 75 kV, a cross-sectional photograph was taken, the layer configuration, and the thickness of each layer Was measured. In some cases, in order to obtain high contrast, a staining technique using RuO ₄ or OsO ₄ was used.

(2) Calculation method of layer thickness The TEM photograph image of about 40,000 times obtained in the item (1) was captured with CanonScanD123U at an image size of 720 dpi. Save the image to a personal computer as a bitmap file (BMP) or compressed image file (JPEG), and then use the image processing software Image-Pro Plus ver.4 (distributor Planetron Co., Ltd.) Was opened and image analysis was performed. In the image analysis process, the relationship between the thickness in the thickness direction and the average brightness of the area sandwiched between the two lines in the width direction was read as numerical data in the vertical thick profile mode. Using the spreadsheet software (Excel2000), the data of the position (nm) and the brightness was adopted in the sampling step 6 (decimation 6), and then numerical processing of a three-point moving average was performed. Furthermore, the obtained data whose brightness changes periodically is differentiated, and the maximum and minimum values of the differential curve are read by a VBA (Visual Basic for Applications) program. The layer thickness was calculated as the layer thickness. This operation was performed for each photograph, and the layer thicknesses of all layers were calculated. Of the obtained layer thickness, a layer having a thickness of 1 μm or more was defined as a thick film layer. The thin film layer was a layer having a thickness of 500 nm or less.

(3) Reflectance / Transmittance Measurement A spectrophotometer (U-4100 Spectrophotometer) manufactured by Hitachi, Ltd. is attached with a 12 ° specular reflection accessory P / N134-0104, and a wavelength of 250 to 500 nm at an incident angle φ = 12 degrees. The absolute reflectance was taken as the reflectance. In addition, the transmittance at an incident angle of 0 ° was measured using the variable angle transmission measurement accessory device to obtain the transmittance. Measurement conditions: The slit was set to 2 nm (visible), the gain was set to 2, and the scanning speed was set to 600 nm / min. The sample was attached to clear glass so that the adhesive surface of the window film was on the glass side, and the measurement was performed such that light was incident from the glass surface side. From these results, the average or maximum transmittance and reflectance of the specific wavelength band shown in Table 1 were obtained. Similarly, the transmittance of the adhesive layer and the hard coat layer was measured in the same manner using a sample formed by coating only the adhesive layer or the hard coat layer in a glassy state.

(4) Calculation of Saturation XYZ under C light source using transmittance at angle 0 ° obtained in (3), spectral distribution of C light source defined in JIS Z 8722, and XYZ color matching function The saturation was calculated using the value and the XYZ value.

(5) Haze The sample created in (3) was measured using a haze meter (HGM-2DP (for C light) manufactured by Suga Test Instruments).

(6) Retention rate of elongation Using Iwasaki Electric Co., Ltd. Eye Super UV Tester SUV-W131, which is an accelerated weathering tester, using an illuminometer, UV intensity of 100 mW / cm in a 60 ° C. × 50% RH atmosphere After adjusting to ² , under the conditions of this apparatus, the window film was installed so that light was irradiated only from the adhesive layer side. Thereafter, the sample after 12 hours of irradiation was taken out, and the elongation before and after the test was measured using a Tensilon AMF / RTA-100 film orientation measuring device manufactured by Orientec Co., Ltd. The measurement was performed under the condition of a speed of 100 mm / min. The ratio of elongation before and after the test (elongation after test / elongation before test) was defined as the elongation retention.

Hereinafter, Examples 5, 7, and 14 shall be read as Reference Examples 5, 7, and 14.
(Example 1)
As the thermoplastic resin A, polyethylene terephthalate (PET) having a melting point of 258 ° C. was used. As the thermoplastic resin B, ethylene terephthalate (PE / SPG · T / CHDC) copolymerized with 25 mol% spiroglycol and 30 mol% cyclohexanedicarboxylic acid, which is an amorphous resin having no melting point, was used. The prepared crystalline polyester and thermoplastic resin B were respectively put into two single-screw extruders, melted at 280 ° C., and kneaded. Next, after passing through 5 sheets of FSS type leaf disk filters, respectively, they were merged with a laminating apparatus having 101 slits while being measured with a gear pump, to obtain a laminated body in which 101 layers were alternately laminated in the thickness direction. . The method for forming a laminate was carried out according to the description in paragraphs [0053] to [0056] of JP-A-2007-307893. Here, the slit length and interval are all constant. The obtained laminate had 51 layers of thermoplastic resin A and 50 layers of thermoplastic resin B, and had a laminated structure in which layers were alternately laminated in the thickness direction. The thickness distribution of each layer in the laminated film is a convex layer thickness distribution in which a thin film layer is provided on both surface layers in the film thickness direction and a thick film layer is provided near the center in the thickness direction. In the film, the majority of the layers from one surface layer to the N / 4 layer and the majority of the layers from the 3N / 4 layer to the Nth layer with respect to the total number N of the laminated film A layer thickness distribution is formed in which the layer thickness is 50 nm or less, and in the layers from N / 4 to 3N / 4 of one surface layer, the layer thickness of 50 nm or more capable of reflecting light having a wavelength near 400 nm is the majority. It was possible. The value obtained by dividing the film width direction length 17 of the base lip, which is the widening ratio inside the base, by the length 15 in the film width direction at the inlet of the base was 2.5.

  The obtained cast film was heated with a roll group set at 75 ° C., and then stretched 3.6 times in the film longitudinal direction while rapidly heating from both sides of the film with a radiation heater between 100 mm in the stretch section length. Once cooled. Subsequently, both sides of this uniaxially stretched film were subjected to corona discharge treatment in air, the wetting tension of the base film was set to 55 mN / m, and the treated surface (polyester resin having a glass transition temperature of 18 ° C.) / (Glass transition) Polyester resin having a temperature of 82 ° C.) / Laminate-forming film coating liquid composed of silica particles having an average particle diameter of 100 nm was applied to form a transparent, easy-sliding, and easy-adhesion layer.

This uniaxially stretched film was guided to a tenter, preheated with hot air at 100 ° C., and then stretched 3.6 times in the film width direction at a temperature of 110 ° C. The stretching speed and temperature here were constant. The stretched film is directly heat-treated with hot air at 240 ° C. in the tenter, followed by 2% relaxation treatment in the width direction under the same temperature condition, and further 5% relaxation in the width direction after quenching to 100 degrees. After the treatment, a wound laminated film was obtained.
Thereafter, a hard coat layer having the following composition was provided on one side of the laminated film on the obtained film using a coater.
A pressure-sensitive adhesive layer was formed by applying a pressure-sensitive adhesive compounded in the following ratio to a surface where a hard coat was not provided using a 100-part coater of acrylic urethane.
Octyl acrylate 50 parts Vinyl acetate 50 parts Hydroxyethyl acrylate 5 parts Melamine resin 10.5 parts The obtained film is affixed on a clear glass having a transmittance of 350 to 400 nm of 90% or more. When the optical properties of saturation and haze were measured, it showed high ultraviolet cut performance at a wavelength of 350 to 400 nm. On the other hand, since the reflectance was not sufficient at a wavelength of 300 to 350 nm, particularly when the elongation retention rate of the film itself was measured by the method described above, a decrease in the elongation retention rate was observed. The results are shown in Table 1.

(Example 2)
A window film was obtained in the same manner as in Example 1 except that the number of layers of the A layer made of the thermoplastic resin A was 101 and the layer thickness of the B layer made of the thermoplastic resin B was 100 layers.
The obtained film was pasted on a clear glass with a transmittance of 350 to 400 nm of 90% or more, and the optical properties of reflectance, transmittance, saturation and haze were measured. It showed performance. Reflecting the results, the film itself was measured for elongation retention by the method described above. As a result, the film showed a higher elongation retention than Example 1. The results are shown in Table 1.

Example 3
A window film was obtained in the same manner as in Example 1 except that the number of layers of the A layer made of the thermoplastic resin A was 201 and the layer thickness of the B layer made of the thermoplastic resin B was 200 layers.
The obtained film was affixed on a clear glass having a transmittance of 350 to 400 nm of 90% or more, and the optical characteristics of reflectance, transmittance, saturation and haze were measured. As compared with Example 2, the film showed higher ultraviolet cut performance, and was a suitable film even when compared with a window film for ultraviolet cut use. Reflecting the results, the film itself was measured for elongation retention by the method described above. As a result, the film showed higher elongation retention compared to Example 2. The results are shown in Table 1.

(Example 4)
A window film was obtained in the same manner as in Example 3 except that the film thickness was adjusted so that the reflection band was shifted by about 10 nm to the higher wavelength side from Example 3.
The obtained film was affixed on a clear glass having a transmittance of 350 to 400 nm of 90% or more, and the optical properties of reflectance, transmittance, saturation and haze were measured. In the same manner as in Example 1, the UV-cutting performance was high, but a slight coloring was observed reflecting the fact that the reflection band shifted to the higher wavelength side. On the other hand, when the film itself was measured for elongation retention by the method described above, it showed high elongation retention as in Example 3. The results are shown in Table 1.

(Example 5)
A window film was obtained in the same manner as in Example 3 except that the film was formed using a laminating apparatus capable of obtaining a layer thickness distribution as described below.
The thickness distribution of each layer in the obtained laminated film is a concave layer thickness distribution in which a thick film layer is provided on both surface layers in the film thickness direction and a thin film layer is provided near the center in the thickness direction. In the film, the majority of the layers from one surface layer to the N / 4 layer and the majority of the layers from the 3N / 4 layer to the Nth layer with respect to the total number N of the laminated film The layer thickness is 50 nm or more capable of reflecting light in the vicinity of a wavelength of 400 nm, and a layer thickness distribution in which the layer thickness of 50 nm or less occupies the majority of the N / 4 to 3N / 4 layers on one surface layer. It was.
Moreover, the obtained film was affixed on a clear glass having a transmittance of 350 to 400 nm of 90% or more, and the optical characteristics of reflectance, transmittance, saturation, and haze were measured. Although it showed a high UV-cut performance as in Example 3, the rise of reflection became broad due to the fact that a layer that reflects light having a wavelength of around 400 nm was provided in the vicinity of the film surface layer, and a slight coloration was observed. It was On the other hand, when the elongation retention rate of the film itself was measured by the method described above, a low elongation retention compared to Example 3 was observed because a thin film layer having a layer thickness of 50 nm or less was present in the central portion of the film thickness. Rate. The results are shown in Table 1.

(Example 6)
A layer thickness configuration in which a thin film layer with a thickness of 50 nm or less is provided on one surface layer side and a thick film layer with a thickness of 50 nm or more is provided on the other surface layer side, and the layer thickness increases uniformly between both surface layers. A window film was obtained in the same manner as in Example 3 except that the film was formed using the laminating apparatus in which
The obtained film is affixed from the surface layer provided with a thin film layer having a thickness of 50 nm or less on a clear glass having a transmittance of 350 to 400 nm of 90% or more, and optical properties of reflectance, transmittance, saturation, and haze. When the characteristics were measured, it showed high UV-cut performance at a wavelength of 300 to 400 nm in the same manner as in Example 3, but reflected by the fact that a layer reflecting light near the wavelength of 400 nm was provided near one film surface layer. The rise of was broad and some coloration was seen. On the other hand, when the elongation retention ratio of the film itself was measured by the method described above, the surface layer provided with the thin film layer having a layer thickness of 50 nm or less was provided on the adhesive layer side, and therefore higher than Example 3. The elongation retention was shown. The results are shown in Table 1.

(Example 7)
The film obtained in Example 6 was pasted from the surface layer side where a thick film layer having a thickness of 50 nm or more was provided on clear glass having a transmittance of 350 to 400 nm of 90% or more, and the reflectance, transmittance, When the optical properties of saturation and haze were measured, it showed high UV-cut performance at a wavelength of 300 to 400 nm as in Example 6, but a layer reflecting light in the vicinity of a wavelength of 400 nm was in the vicinity of one film surface layer. As a result, the rising of the reflection became broad, and a slight coloration was observed. On the other hand, when the elongation retention rate of the film itself was measured by the method described above, the surface layer provided with a thick film layer having a layer thickness of 50 nm or more was provided on the adhesive layer side, and therefore lower than Example 6. The elongation retention was shown. The results are shown in Table 1.

(Example 8)
A window film was obtained in the same manner as in Example 3 except that only the adhesive layer was provided without providing a hard coat.
The obtained film was affixed on a clear glass having a transmittance of 350 to 400 nm of 90% or more, and the optical properties of reflectance, transmittance, saturation and haze were measured. In the same manner as above, it showed high UV-cut performance. On the other hand, when the film itself was measured for elongation retention by the method described above, it showed high elongation retention as in Example 3. The results are shown in Table 1.

Example 9
A window film was obtained in the same manner as in Example 3 except that 0.1 part of 2- (2-hydroxy-5-tert-octylphenyl) benzotriazole was further added to the adhesive layer.
The obtained film was affixed on a clear glass having a transmittance of 350 to 400 nm of 90% or more, and the optical properties of reflectance, transmittance, saturation and haze were measured. Even higher UV cut performance was exhibited. On the other hand, when the film itself was measured for elongation retention by the method described above, it showed a higher elongation retention than Example 3. The results are shown in Table 1.
The obtained window film is excellent in UV blocking performance and light resistance. Actually, the glass with the window film attached is used, and the pair with the window film attached surface becomes the inner surface of the outdoor glass. When the glass was assembled, it showed high UV-cutting performance, and no deterioration behavior such as color change or peeling was confirmed even after long-term use.

(Example 10)
A window film was obtained in the same manner as in Example 3 except that 0.1 part of 2- (2-hydroxy-5-tert-octylphenyl) benzotriazole was further added to the hard coat layer.
The obtained film was affixed on a clear glass having a transmittance of 350 to 400 nm of 90% or more, and the optical properties of reflectance, transmittance, saturation and haze were measured. Even higher UV cut performance was exhibited. On the other hand, when the film itself was measured for elongation retention by the method described above, it showed high elongation retention as in Example 3. The results are shown in Table 1.

(Example 11)
A window film was obtained in the same manner as in Example 3 except that 0.5 wt% of LA-F70 (made by ADEKA) which is an ultraviolet absorber satisfying the formula (1) was added to the thermoplastic resin A and the thermoplastic resin B. It was. The triazine compound contained in LA-F70 had a glass transition temperature of 150 ° C. or higher and was excellent in heat resistance, but some precipitation was observed in the production apparatus.
The obtained film was pasted on a clear glass having a transmittance of 350 to 400 nm of 90% or more, and the optical characteristics of reflectance, transmittance, saturation, and haze were measured, and the transmittance was 5% even at a wavelength of 380 nm. And extremely low values, and even higher UV-cut performance. On the other hand, when the film itself was measured for elongation retention by the method described above, it showed higher elongation retention than Example 3. The results are shown in Table 1.

(Example 12)
A window film was obtained in the same manner as in Example 3 except that 2.0 wt% of LA-F70 (made by ADEKA), which is an ultraviolet absorber satisfying the formula (1), was added to the thermoplastic resin A and the thermoplastic resin B. It was. The triazine compound contained in LA-F70 has a glass transition temperature of 150 ° C. or higher and is excellent in heat resistance. However, it is not suitable for continuous film formation over a long period of time due to precipitation on the production equipment. There wasn't.
The obtained film was affixed on a clear glass having a transmittance of 350 to 400 nm of 90% or more, and the optical properties of reflectance, transmittance, saturation, and haze were measured, and the transmittance was 2% even at a wavelength of 380 nm. And extremely low values, and extremely high UV-cut performance. On the other hand, the film itself showed a very high elongation retention when the elongation retention was measured by the method described above. The results are shown in Table 1.

(Example 13)
A window film was obtained in the same manner as in Example 3, except that 1.0 wt% of LA-F70 (manufactured by ADEKA), which is an ultraviolet absorber satisfying the formula (1), was added to the thermoplastic resin B. The triazine compound contained in LA-F70 had a glass transition temperature of 150 ° C. or higher and was excellent in heat resistance. Moreover, almost no precipitation was observed on the production apparatus which is an ultraviolet absorber, and the continuous productivity was excellent.
The obtained film was pasted on a clear glass having a transmittance of 350 to 400 nm of 90% or more, and the optical characteristics of reflectance, transmittance, saturation, and haze were measured, and the transmittance was 5% even at a wavelength of 380 nm. And extremely low values, and even higher UV-cut performance. On the other hand, when the film itself was measured for elongation retention by the method described above, it showed a high elongation retention as in Example 11. The results are shown in Table 1.

(Example 14)
The layer number of the A layer made of the thermoplastic resin A is 301 layers, the layer thickness of the B layer made of the thermoplastic resin B is 300 layers, and the majority of the layers of the A and B layers has a layer thickness of 150 to 200 nm. Except for the above, a window film was obtained in the same manner as in Example 3. The obtained laminated film exhibited a characteristic of reflecting light in a wavelength band of 850 to 1200 nm and a wavelength of 410 nm or less.
The obtained film was pasted on a clear glass having a transmittance of 350 to 400 nm of 90% or more, and the optical properties of reflectance, transmittance, saturation and haze were measured. And a heat ray cutting performance accompanying reflection of near infrared rays of 850 to 1200 nm. The results are shown in Table 1.

(Comparative Example 1)
A window film was obtained in the same manner as in Example 1 except that the number of layers of the A layer made of the thermoplastic resin A was 25 and the layer thickness of the B layer made of the thermoplastic resin B was 24.
The obtained film was affixed on a clear glass having a transmittance of 350 to 400 nm of 90% or more, and the optical properties of reflectance, transmittance, saturation and haze were measured. It showed an ultraviolet cut performance. Reflecting the results, the film itself was measured for elongation retention by the method described above. As a result, the film itself showed a lower elongation retention than Example 1. The results are shown in Table 1.

(Comparative Example 2)
A window film was obtained in the same manner as in Example 1 except that a PET film composed of a single layer of PET resin was used instead of the laminated film.
The obtained film was affixed to clear glass with a transmittance of 350 to 400 nm of 90% or more, and when measured for optical properties of reflectance, transmittance, saturation and haze, it showed almost no UV cut performance. Met. Reflecting the results, the film itself showed a low elongation retention when the elongation retention was measured by the method described above. The results are shown in Table 1.

The present invention relates to a window film capable of cutting ultraviolet rays caused by sunlight or the like. More specifically, the present invention relates to a window film that has an achromatic color but has a high UV-cutting performance and a good light resistance even when used for a long period of time, and is suitable for use in window glass of automobiles, trains, buildings, etc. It is.

Claims (15)

A laminated film in which 51 layers or more of A layers made of thermoplastic resin A and B layers made of thermoplastic resin B are alternately laminated, and an adhesive layer is provided on one surface of the laminated film, a bonded together are used in window films state, and are the maximum reflectance is 50% or more at a wavelength of 350 to 400 nm, transmittance at a wavelength 420nm of the laminated film is 50% or more, in the laminated film The layer thickness of the majority of the layers from the surface layer on the adhesive layer side to the N / 4 layer with respect to the total number N of the laminated films is 50 nm or less, and N / 4 to 3N / 4 on the adhesive layer side. A window film having a layer thickness of 50 nm or more in layers up to the first layer . The window film according to claim 1, wherein an average reflectance at a wavelength of 350 to 400 nm is 70% or more. The window film according to claim 1 or 2, wherein the maximum transmittance at a wavelength of 300 to 380 nm is 30% or less. The window film according to claim 1, wherein the reflectance at a wavelength of 380 nm is 50% or more and the reflectance at a wavelength of 420 nm is 20% or less. The window film according to any one of claims 1 to 4, wherein the saturation of transmitted light in the C light source is 4.8 or less. The window film according to claim 1 , wherein the saturation of transmitted light in the C light source is 3.0 or less. The window film according to any one of claims 1 to 6 , wherein an elongation retention when irradiated with a halogen lamp at 100 mW / cm ² for 12 hours is 50% or more. The window film according to any one of claims 1 to 7, wherein a haze is 1.5% or less. The window film according to claim 1, wherein a hard coat layer is further provided on an opposite surface of the laminated film to the adhesive layer. The ultraviolet-ray absorber is further included in the said adhesion layer or / and a hard-coat layer, and the transmittance | permeability with a wavelength of 400 nm of the layer containing an ultraviolet absorber is 80% or more of Claims 1-9 characterized by the above-mentioned. A window film according to any one of the above. The window film according to any one of claims 1 to 10, wherein both surface layers of the laminated film are made of the thermoplastic resin A, and the thermoplastic resin B contains an ultraviolet absorber. The window film according to claim 10 or 11, wherein the addition amount of the ultraviolet absorber is 1 wt% or less in the entire window film. The window film according to claim 12, wherein the ultraviolet absorber is a triazine compound satisfying the following formula (1), and the melting point of the triazine compound is 120 ° C or higher. Alkyl group).

The window film according to claim 1, comprising 50 or more layers having a layer thickness of 150 to 200 nm of the laminated film. Two opposing glasses are provided with a space of at least 0.1 mm or more, and the window film according to any one of claims 1 to 14 is attached to the inner surface of at least one glass. A composite glass body characterized by