JP2016126097A - Optical reflective film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical reflective film that features minimal temporal discoloration.SOLUTION: An optical reflective film includes an optical reflective layer having at least one unit comprising a high refractive index layer containing titanium oxide and a low refractive index layer laminated together. The optical reflective layer contains cerium oxide, and cerium oxide content is 1-30 vol.% with respect to total titanium oxide content in the optical reflective layer.SELECTED DRAWING: None

Description

  The present invention relates to an optical reflection film.

  In recent years, heat shielding films and laminated glass with high heat insulation or heat ray blocking properties have been distributed in the market in order to block the heat felt by human skin due to the influence of the sun entering from the car window, suppress the operation of the air conditioner in the car and save energy doing.

  In general, laminated glass has an optical reflection film disposed between a pair of plate glasses, and the optical reflection film blocks the transmission of heat rays (infrared rays) of sunlight to reduce indoor temperature rise and cooling load.

  Due to the recent expansion of ITS (Intelligent Transport Systems) and the widespread use of mobile terminals, the need for electromagnetic wave transmission is also increasing in thermal barrier films for windows. In a reflection film using a general metal film (Ag or the like), an electromagnetic wave is cut off. Therefore, a near-infrared reflection film using a dielectric laminated film is used to provide electromagnetic wave permeability. Titanium oxide is used as a high refractive index material for such a dielectric laminated film (for example, see Patent Document 1).

  By the way, the ultraviolet degradation of titanium oxide used as metal oxide fine particles is known, and various studies have been made for the purpose of suppressing such degradation. For example, Patent Document 2 discloses a technique in which a cobalt complex is contained in titanium oxide fine particles used as a coating for a high refractive index resin lens of a plastic spectacle lens. With such a structure, excitation of titanium oxide particles by ultraviolet rays is suppressed, and blue coloring of the coating is suppressed.

International Publication No. 2012/014607 JP 2014-38293 A

  Since the optical reflection film is used as a heat-shielding film or laminated glass, it is exposed to strong sunlight for a long time, and may be installed in a severe humidity environment for a long time. For this reason, long-term weather resistance is required for the optical reflective film.

  However, in the optical reflection film manufactured using the technique of Patent Document 2, discoloration occurs due to exposure to ultraviolet rays for a long time, and long-term weather resistance in an ultraviolet environment cannot be said to be sufficient.

  Accordingly, an object of the present invention is to provide an optical reflective film that suppresses discoloration over time.

  The optical reflective film of the present invention is an optical reflective film having an optical reflective layer including at least one unit obtained by laminating a high refractive index layer containing titanium oxide and a low refractive index layer, and the optical reflective layer is oxidized. It contains cerium and is characterized in that the content of cerium oxide is 1 to 30% by volume with respect to the total amount of titanium oxide contained in the optical reflection layer.

  According to the present invention, it is possible to provide an optical reflection film that suppresses discoloration over time.

It is a schematic sectional drawing (FIG. 1A) of the optical reflection film which concerns on suitable embodiment. It is a schematic sectional drawing (FIG. 1B) at the time of sticking the optical reflection film which concerns on suitable embodiment to a base | substrate (for example, window glass).

  The first embodiment of the present invention is an optical reflective film having an optical reflective layer including at least one unit in which a high refractive index layer containing titanium oxide and a low refractive index layer are stacked, and the optical reflective layer is The content of cerium oxide is 1 to 30% by volume with respect to the total amount of titanium oxide contained in the optical reflection layer, including cerium oxide.

  By adjusting the optical characteristics of each layer in an optical reflective film that has a laminated unit in which high-refractive index layers and low-refractive index layers are alternately laminated, light in a specific wavelength region such as near infrared rays, far infrared rays, visible light, ultraviolet rays, etc. It is known that it can be designed to reflect.

  Here, when the optical reflection film obtained by applying titanium oxide (titanium dioxide particles) -containing particles and a cobalt complex together with a resin as in Patent Document 2 is exposed to strong sunlight for a long time, It has been found that there is a problem that the color tone fluctuates.

  As a cause of such coloration over time, the present inventor considered that the above-described cobalt complex does not have a sufficient effect of suppressing ultraviolet rays on titanium oxide particles. And this inventor performed various examination in the optical reflective film in order to suppress the color tone fluctuation | variation at the time of being exposed to strong sunlight for a long time. As a result, surprisingly, when titanium oxide constitutes the refractive index layer, coloring with time is caused when 1 to 30% by volume of cerium oxide is contained in any one of the optical reflection layers with respect to titanium oxide. Has been found to be suppressed.

  Although the mechanism by which coloring with time by titanium oxide is suppressed by using a small amount of cerium oxide with respect to titanium oxide is unknown, it is presumed as follows.

  Cerium oxide has an energy gap of 3.0 to 3.1 eV and can cut to the long-wave side UV equivalent to titanium oxide, and can block UV light in a wavelength range considered to be a cause of coloring of titanium oxide. Is possible.

  The present inventor has also found that coloring with time is further suppressed by allowing cerium oxide to coexist in the titanium oxide-containing layer. Cerium oxide has a low reduction potential (acts as a strong oxidizing agent) and can suppress the self-reduction reaction of titanium oxide. Therefore, coexistence with the titanium oxide layer has both effects of UV cut effect and suppression effect of titanium oxide self-reduction reaction. It is considered that discoloration can be suppressed.

  Embodiments of the present invention will be described below. In addition, this invention is not limited only to the following embodiment. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation, and may be different from the actual ratios.

  In this specification, “X to Y” indicating a range means “X or more and Y or less”. Unless otherwise specified, measurement of operation and physical properties is performed under conditions of room temperature (20 to 25 ° C.) / Relative humidity 40 to 50%.

<Optical reflection film>
The optical reflection film can be made into a visible light reflection film or a near-infrared reflection film by changing a specific wavelength region for increasing the reflectance. That is, if the specific wavelength region for increasing the reflectance is set to the visible light region, the visible light reflecting film is obtained, and if the specific wavelength region is set to the near infrared region, the near infrared reflecting film is obtained. In the case of a near-infrared reflective film, the transmittance at 550 nm in the visible light region shown in JIS R3106: 1998 is preferably 50% or more, more preferably 70% or more, and 75% or more. Is more preferable. Further, the transmittance at 1200 nm is preferably 35% or less, more preferably 25% or less, and further preferably 20% or less. It is preferable to design the optical film thickness and unit so as to be in such a suitable range. Moreover, it is preferable to have the area | region which has a reflectance exceeding 50% in the area | region of wavelength 900nm-1400nm.

<Optical reflection layer>
The optical reflection film has an optical reflection layer as its basic layer structure.

  The optical reflection layer is a dielectric multilayer film that is a laminate of a plurality of optical thin films, and may have a configuration having at least one laminate (unit) in which a high refractive index layer and a low refractive index layer are laminated. Preferably, the optical reflection layer preferably has a form in which high refractive index layers and low refractive index layers are alternately laminated.

  In this specification, the terms “high refractive index layer” and “low refractive index layer” refer to a refractive index layer having a higher refractive index when comparing the refractive index difference between two adjacent layers. It means that the lower refractive index layer is a low refractive index layer. Therefore, the terms “high refractive index layer” and “low refractive index layer” mean that each refractive index layer has the same refractive index when attention is paid to two adjacent refractive index layers. All forms other than the forms having the above are included.

  In addition, a component constituting the high refractive index layer (hereinafter referred to as “high refractive index layer component”) and a component constituting the low refractive index layer (hereinafter referred to as “low refractive index layer component”) are mixed at the interface between the two layers, A layer (mixed layer) including a refractive index layer component and a low refractive index layer component may be formed. In this case, in the mixed layer, a set of portions where the high refractive index layer component is 50% by mass or more is defined as a high refractive index layer, and a set of portions where the low refractive index layer component exceeds 50% by mass is defined as a low refractive index layer. . Specifically, when the low refractive index layer contains, for example, a metal oxide as a low refractive index layer component, the metal oxide concentration profile and the titanium oxide concentration profile in the film thickness direction of these laminated films are obtained. It can be regarded as a high refractive index layer or a low refractive index layer depending on the composition measured. The metal oxide concentration profile and the titanium oxide concentration profile of the laminated film were etched from the surface to the depth direction using a sputtering method, and the outermost surface was set to 0 nm by using an XPS surface analyzer. It can be observed by sputtering at a speed and measuring the atomic composition ratio. Further, even in a laminate in which the metal oxide particles are not contained in the low refractive index layer component and the low refractive index layer is formed only from the organic binder, in the organic binder concentration profile, for example, By measuring the carbon concentration in the film thickness direction, it is confirmed that the mixed region exists, and by measuring the composition by EDX, each layer etched by sputtering is either a high refractive index layer or a low refractive index layer. It can be regarded as a rate layer.

  The number of high refractive index layers and low refractive index layers (total number of refractive index layers) is not particularly limited, but is preferably 6 to 2000 (that is, 3 to 1000 units), more preferably 10 to 1000 ( That is, it is 5-500 units), More preferably, it is 10-500 (namely, 5-250 units). If the number of layers exceeds 2000, haze increases, and if it is less than 6, the desired reflectance may not be achieved. Moreover, the optical reflection film should just be the structure which has at least 1 or more units on the said base material. For example, the outermost layer (the lowermost layer and the outermost layer) of the optical reflection layer may be either a high refractive index layer or a low refractive index layer. However, by adopting a layer configuration in which the low refractive index layer is located in the outermost layer of the optical reflection layer, the adhesion to the adjacent layer (for example, the base material) of the lowermost layer, the refractive index difference with the air or the adhesive layer is reduced. A layer configuration in which the outermost layer of the optical reflection layer is a low refractive index layer is preferable from the viewpoint of reducing and suppressing interface reflection and being excellent in efficiently introducing incident light into the reflection layer.

  In the optical reflection layer, the high refractive index layer preferably has a higher refractive index, but the refractive index is preferably 1.70 to 2.50, more preferably 1.80 to 2.20. The low refractive index layer preferably has a lower refractive index, but preferably has a refractive index of 1.10 to 1.60, more preferably 1.30 to 1.55, and even more preferably 1. 30 to 1.50.

  The reflectance in the specific wavelength region is determined by the difference in refractive index between the two adjacent layers (high refractive index layer and low refractive index layer) and the number of layers. In the optical reflective layer, the reflectance between the high refractive index layer and the low refractive index layer is Designing a large difference in refractive index is preferable from the viewpoint of increasing the optical reflectance with a small number of layers. In at least one of the units composed of the high refractive index layer and the low refractive index layer, the difference in refractive index between the adjacent high refractive index layer and low refractive index layer is preferably 0.1 or more, more preferably Is 0.2 or more, more preferably 0.25 or more. When the optical reflective layer has a plurality of units of the low refractive index layer and the high refractive index layer, the refractive index difference between the low refractive index layer and the high refractive index layer in all the units may be within the preferred range. preferable. However, the outermost layer and the lowermost layer of the optical reflection layer may have a configuration outside the above preferred range. From the viewpoint of improving the reflectance and reducing the number of layers, there is no upper limit to the difference in refractive index, but it is substantially about 1.4.

  The refractive index is obtained as the difference between the refractive indexes of the high refractive index layer and the low refractive index layer according to the following method. That is, each refractive index layer is formed as a single layer (using a base material if necessary), and after cutting this sample into 10 cm × 10 cm, the refractive index is obtained according to the following method. Using a U-4000 type (manufactured by Hitachi, Ltd.) as a spectrophotometer, the surface opposite to the measurement surface (back surface) of each sample is roughened, and then light absorption is performed with a black spray. Then, the reflection of light on the back surface is prevented, and the reflectance in the visible light region (400 nm to 700 nm) is measured at 25 points under the condition of regular reflection at 5 degrees to obtain an average value, and the average refractive index is determined from the measurement result. Ask.

  In addition, when viewed as a single layer film, the optical path difference between the reflected light on the surface of the layer and the reflected light on the bottom of the layer can be controlled to enhance the reflected light by the phase difference if the relationship expressed by n · d = wavelength / 4. , Can increase the reflectance. Here, n is the refractive index, d is the physical film thickness of the layer, and n · d is the optical film thickness. By using this optical path difference, reflection can be controlled. Using this relationship, the refractive index and film thickness of each layer are controlled to control the reflection of visible light and near infrared light. That is, the reflectance in a specific wavelength region can be increased by the refractive index of each layer, the film thickness of each layer, and the way of stacking each layer.

  The thickness per layer of the low refractive index layer and the high refractive index layer (thickness after drying) is appropriately set so as to have desired optical characteristics. It is preferably 1000 nm, more preferably 50 to 500 nm, even more preferably 100 to 300 nm, and particularly preferably 100 to 200 nm. The thickness of the low refractive index layer and the high refractive index layer may be the same or different. The thickness per layer of each refractive index layer can be adjusted by changing the width in the film thickness direction at the die extrusion port and / or by stretching conditions. In addition, when extending | stretching a laminated body, the said film thickness shows the thickness after extending | stretching.

  The optical reflection layer includes cerium oxide. The location where cerium oxide is contained may be any refractive index layer that forms the optical reflection layer. Since the refractive index of cerium oxide itself is high, when titanium oxide is used to adjust the refractive index of the dielectric multilayer film, the adjustment of the refractive index becomes complicated if cerium oxide is added, so it is usually oxidized with cerium oxide. It is not usually used in combination with titanium. In addition, an ultraviolet absorber or the like has been added to the sunlight incident side of an optical reflection layer such as an adhesive layer or a hard coat layer so far to provide an ultraviolet shielding ability. However, the present inventors have found that the ultraviolet rays that have passed through these outermost layers reach titanium oxide in the optical reflection layer and cause coloring of the optical reflection layer, and provide the optical reflection layer with an ultraviolet shielding ability. I got the idea. Furthermore, even if the optical reflection layer has an ultraviolet shielding ability, generally used organic UV absorbers have a significantly reduced UV shielding ability over time. It was not sufficient for applications requiring weatherability. In addition, for example, rutile titanium oxide has a band gap energy of 3.0 eV, and absorption starts from a relatively long wavelength (400 nm). Therefore, by effectively suppressing this region, there is a band gap energy after the weather resistance test. However, it was thought that coloring of titanium oxide might be significantly suppressed.

  Under such an idea, by adding a small amount of cerium oxide to titanium oxide, coloring of titanium oxide after the weather resistance test is remarkably suppressed, and thus long-term weather resistance is required. It has been found that the configuration of the first embodiment is effective in the optical reflection film.

  The cerium oxide-containing layer in the optical reflection layer is not particularly limited, and may be contained in any one of the high refractive index layer and the low refractive index layer. Specifically, the outermost layer of either or both of the optical reflective layers contains cerium oxide; the high refractive index layer containing titanium oxide contains cerium oxide; the low refractive index layer contains cerium oxide The form to make; and the combination of these forms etc. are considered. Since each refractive index layer can have a UV shielding effect, it is preferable to include cerium oxide in any of all the low refractive index layers and all the high refractive index layers. In addition, since it is possible to reduce UV exposure to titanium oxide in the optical reflection layer, it is preferable to contain cerium oxide in the uppermost layer on the light source (for example, sunlight) side, and the lower refractive index of the uppermost layer on the light source side. More preferably, the rate layer contains cerium oxide.

  In the present embodiment, it is preferable that at least the high refractive index layer contains cerium oxide because the effect can be obtained more remarkably. By allowing cerium oxide to coexist with titanium oxide, coloring after the weather resistance test can also be suppressed. Titanium oxide becomes trivalent by self-reduction reaction due to absorption of ultraviolet rays, but cerium oxide has a low reduction potential and acts as a strong oxidant. Therefore, it is considered that the self-reduction reaction of titanium oxide can be suppressed.

  Furthermore, in the form in which the high refractive index layer contains cerium oxide, it is preferable that the outermost layer of the optical reflection layer is a low refractive index layer, and any one of the outermost low refractive index layers contains cerium oxide. The outermost layer of the optical reflection layer can be, for example, the incident light side of sunlight (hereinafter simply referred to as the incident light side). Therefore, if cerium oxide is contained in the outermost layer, ultraviolet rays reach the optical reflection layer. This can be suppressed, and the effect of suppressing film coloring over time is increased. The outermost layer on the incident light side of the optical reflection layer is determined by being attached to the substrate. For example, window films intended for heat ray shielding include an internal application that attaches the film to the substrate from the indoor side and an external application that attaches to the substrate from the outside air side. The configuration is determined. Therefore, a mode in which cerium oxide is contained in the outermost layer on the incident light (for example, sunlight) side when attached to the substrate is preferable. In addition, when the outermost layer of the optical reflective layer is a low refractive index layer, the outermost layer may be a two-layer laminated form of a low refractive index layer having a refractive index lower than that of the high refractive index layer for the purpose of thickness adjustment or the like. is there. In this case, cerium oxide is preferably contained at least in the low refractive index layer on the surface layer side. The content ratio of cerium oxide contained in the high refractive index layer and the content ratio of cerium oxide contained in the outermost low refractive index layer of the optical reflection layer are not particularly limited as long as the effect of the present invention is exhibited. However, the content of cerium oxide contained in the high refractive index layer: the content of cerium oxide contained in the outermost low refractive index layer is preferably 1: 0.1 to 5 (volume ratio), and 1: 0 More preferably, it is 5-2.

  Further, as a preferred embodiment, the optical reflection film preferably has a pressure-sensitive adhesive layer and the outermost (refractive index) layer closest to the pressure-sensitive adhesive layer contains cerium oxide. FIG. 1: is a schematic sectional drawing (FIG. 1A) of the optical reflection film which concerns on suitable embodiment, and a schematic sectional drawing (FIG. 1B) at the time of sticking the said optical reflection film on a base | substrate (for example, window glass). The optical reflective film 1 in FIG. 1A is formed by laminating an adhesive layer 2, an optical reflective layer 3, a base material 4, and a hard coat layer 5 in this order. In this embodiment, the outermost layer closest to the pressure-sensitive adhesive layer 2 of the optical reflection layer 3 contains cerium oxide. Moreover, FIG. 1B is the figure which affixed the optical reflection film 1 of FIG. 1A from the room inner side of the base | substrate 6 (internal sticking). As shown in FIG. 1B, when the inner layer is applied, the pressure-sensitive adhesive layer side becomes the incident light (for example, sunlight) side, so that the outermost (refractive index) layer closest to the pressure-sensitive adhesive layer contains cerium oxide. Thus, it is possible to suppress the arrival of ultraviolet rays into the optical reflection layer, and the effect of suppressing film coloring over time is further increased. The hard coat layer can be disposed for the purpose of protecting the optical reflective layer from the outside, but is not an essential constituent element in the present invention.

  The volume average particle diameter of cerium oxide is preferably less than 1000 nm, more preferably 1 to 100 nm, and even more preferably 1 to 50 nm. Since the volume average particle diameter of cerium oxide is within the above range, transparency is secured, which is preferable. Moreover, since the volume average particle diameter of a cerium oxide is 100 nm or less, Preferably it is 50 nm or less, since the film coloring inhibitory effect over time increases further, it is preferable. Here, the volume average particle diameter of cerium oxide refers to the volume average particle diameter of the surface-treated cerium oxide when cerium oxide is surface-treated.

  In the present specification, the volume average particle diameter is a volume represented by the volume average particle diameter mv = {Σ (vi · di)} / {Σ (vi)} by a laser diffraction scattering method. The average particle size weighted with

  The cerium oxide may be subjected to a surface treatment for the purpose of improving dispersibility in the refractive index layer. For example, when the refractive index layer contains a water-soluble polymer (for example, polyvinyl alcohol) described later, it is preferable to perform a hydrophilic surface treatment. In addition, since the surface treatment depends on the configuration of the refractive index layer used in combination, if a water repellent surface treatment is required, a water repellent treatment such as an organosiloxane treatment, a fluorine compound treatment, or an oil agent treatment may be performed.

  Examples of the hydrophilized surface treatment include boron nitride treatment, silica treatment, agar treatment, deoxyribonucleic acid treatment, lecithin treatment, polyacrylic acid treatment, alumina treatment or zirconia treatment. Among these, in the present invention, silica treatment and boron nitride treatment are preferable from the viewpoint of dispersibility as a water-based paint and covering property for suppressing catalytic action.

  Such surface-treated cerium oxide may be synthesized or commercially available. Examples of synthesis methods include cosmetology research reports. No. 10 (2002). Examples include the method described in the development of a cerium oxide-based ultraviolet blocking agent.

  Although content with respect to the cerium oxide of a surface treating agent is not specifically limited as long as the surface treatment effect is exhibited, It is preferable that it is 5-100 mass% with respect to cerium oxide.

  The cerium oxide is preferably blended in the refractive index layer forming liquid in a dispersion state. Since cerium oxide tends to aggregate itself, it is preferable that cerium oxide alone is sufficiently dispersed in advance. Commercially available products may be used as such a dispersion, and examples of commercially available products include Nidoral P10 (manufactured by Taki Chemical Co., Ltd.), NANOBYK (registered trademark) -3810 (manufactured by BYK).

  The content of cerium oxide contained in the optical reflection layer is 1 to 30% by volume with respect to the total amount of titanium oxide contained in the optical reflection layer. When the amount is less than 1% by volume, the effect of suppressing coloration with time by cerium oxide is difficult to be exhibited, and when the amount is 30% by volume or more, the influence of the photocatalytic action of cerium oxide becomes remarkable, which causes deterioration of the optical reflection layer. . The content of cerium oxide contained in the optical reflection layer is preferably 3 to 20% by volume with respect to the total amount of titanium oxide contained in the optical reflection layer, from the viewpoint of the color of the film and the effect of suppressing discoloration. More preferably, it is 10 volume%.

  In addition, content of cerium oxide here points out content of surface-treated cerium oxide, when cerium oxide is surface-treated. Similarly, the total amount of titanium oxide is the amount of surface-treated titanium oxide when titanium oxide is surface-treated (for example, core-shell particles coated with the following silicon-containing hydrated oxide). Point to.

  The high refractive index layer includes titanium oxide. Titanium oxide is used because it is transparent and has a higher refractive index.

  The volume average particle diameter of titanium oxide used in the high refractive index layer is preferably 100 nm or less, more preferably 50 nm or less, and 1 nm or more from the viewpoint of a low haze value and excellent visible light transmittance. More preferably it is. Here, the volume average particle diameter of titanium oxide is the surface treatment when titanium oxide is surface-treated (for example, core-shell particles coated with a silicon-containing hydrated oxide described below). It refers to the volume average particle diameter of titanium oxide.

  When the transparency of the entire optical reflection layer is ensured and the haze value and visible light transmittance are taken into consideration, the volume average particle diameter of cerium oxide and titanium oxide is preferably 1 to 100 nm, and preferably 1 to 50 nm. Is more preferable.

  The titanium oxide may be in the form of core-shell particles coated with a silicon-containing hydrated oxide. The core-shell particles have a structure in which the surface of the titanium oxide particles is coated with a shell made of a silicon-containing hydrated oxide on a titanium oxide serving as a core. By including such core-shell particles in the high refractive index layer, when the high refractive index layer contains a water-soluble polymer, due to the interaction between the silicon-containing hydrated oxide of the shell layer and the water-soluble polymer, In addition, interlayer mixing between the low refractive index layer and the high refractive index layer can be suppressed. Here, the “coating” means a state in which a silicon-containing hydrated oxide is attached to at least a part of the surface of the titanium oxide particles. That is, the surface of the titanium oxide particles used as the metal oxide particles may be completely covered with a silicon-containing hydrated oxide, and a part of the surface of the titanium oxide particles is a silicon-containing hydrated oxide. It may be coated. From the viewpoint that the refractive index of the coated titanium oxide particles is controlled by the coating amount of the silicon-containing hydrated oxide, it is preferable that a part of the surface of the titanium oxide particles is coated with the silicon-containing hydrated oxide. . Hereinafter, such coated titanium oxide particles are also referred to as “silica-attached titanium dioxide sol”. As a method of coating the titanium oxide particles with a silicon-containing hydrated oxide, it can be produced by a conventionally known method. For example, JP-A-10-158015, JP-A-2000-204301, JP-A-2007 Reference can be made to the matters described in JP-A-246351.

  The content of titanium oxide in the high refractive index layer is 20 to 80% by mass because the effect of suppressing coloring of titanium oxide by cerium oxide is remarkably obtained with respect to 100% by mass of the solid content of the high refractive index layer. It is preferable that it is 30-75 mass%, and it is more preferable that it is 40-70 mass%. The content of titanium oxide in the high refractive index layer is such that when titanium oxide is surface-treated (for example, core-shell particles coated with the above silicon-containing hydrated oxide), the surface-treated titanium oxide Refers to the amount.

  The refractive index layer constituting the optical reflection layer is not particularly limited as long as the dielectric multilayer film is formed. Hereinafter, a preferable embodiment will be described as the optical reflection layer.

(polymer)
The refractive index layer constituting the optical reflection layer preferably contains a polymer. By using the polymer in this manner, the flexibility of the layer is improved as compared with the optical reflection layer of the inorganic film formed only of the metal oxide material, and thus the film cracking can be effectively prevented. Moreover, the adhesiveness between each layer can be improved. Furthermore, since the optical reflection layer can be formed by coating or the like, uniform and large-area film formation is easy. Moreover, since the film forming speed can be increased, it is preferable from the viewpoint of manufacturing cost and mass production. In addition, since there is no need to form a film at a high temperature, the substrate can be selected in a wide range. ) Can be effectively prevented from peeling off due to the difference in shrinkage ratio between the two.

  More preferably, the optical reflection layer has at least one laminate (unit) in which a high refractive index layer containing a polymer and a low refractive index layer containing a polymer are laminated. Below, a more preferable form is demonstrated.

  The polymer used in the refractive index layer is not particularly limited. Each refractive index layer can be formed using a polymer by a film forming method such as coating or spin coating. Since these methods are simple and do not ask the heat resistance of a base material, there are many choices, and it can be said that it is an effective film forming method particularly for a resin base material. For example, a mass production method such as a roll-to-roll method can be adopted for the coating type, which is advantageous in terms of cost and process time. Moreover, since the film | membrane containing a polymer material has high flexibility, even if it winds up at the time of production or conveyance, these defects do not generate easily and there exists an advantage that it is excellent in handleability.

  Among these, the polymer is preferably a water-soluble polymer. In the present invention, in the system in which the refractive index of the high refractive index layer is increased with titanium oxide, a particularly remarkable effect is obtained when cerium oxide is contained, and a water-soluble polymer is used as a binder in such a system. And can be produced by a coating mold. In addition, by including a water-soluble polymer in the high-refractive index layer and the low-refractive index layer, a layer forming method that suppresses the use of an organic solvent can be adopted, which can solve environmental problems caused by organic solvents. It is also preferable because the flexibility of the coating film can also be achieved.

  The polymers contained in the high refractive index layer and the low refractive index layer may be the same component or different components. Examples of the water-soluble polymer include polyvinyl alcohol or a derivative thereof (polyvinyl alcohol-based resin), gelatin, or thickening polysaccharide. From the viewpoint of improving effects such as coating unevenness and film thickness uniformity (haze). Therefore, the refractive index layer preferably contains polyvinyl alcohol or a derivative thereof as a polymer. A polymer may be used independently and may be used in combination of 2 or more type. The polymer may be a synthetic product or a commercially available product.

  The polymer is not particularly limited, and known polymers used for the high refractive index layer and the low refractive index layer such as International Publication No. 2012/128109, JP2013-121567A, JP2013-148849A, and the like. It can be used similarly. Specifically, the polyvinyl alcohol-based resin includes various modified polyvinyl alcohols in addition to ordinary polyvinyl alcohol obtained by hydrolyzing polyvinyl acetate.

  Polyvinyl alcohol preferably has an average degree of polymerization of 1,000 or more, and particularly preferably an average degree of polymerization of 1,500 to 5,000. Moreover, it is preferable that it is 70-100 mol%, and, as for saponification degree, it is especially preferable that it is 80-99.9 mol%.

  Examples of the modified polyvinyl alcohol include cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, nonion-modified polyvinyl alcohol, ethylene-modified polyvinyl alcohol, and vinyl alcohol polymers. Also, vinyl acetate resins (for example, “Exeval” manufactured by Kuraray Co., Ltd.), polyvinyl acetal resins obtained by reacting polyvinyl alcohol with aldehydes (for example, “ESREC” manufactured by Sekisui Chemical Co., Ltd.), silanols having silanol groups Modified polyvinyl alcohol (for example, “R-1130” manufactured by Kuraray Co., Ltd.), modified polyvinyl alcohol resin having an acetoacetyl group in the molecule (for example, “Gosefimer (registered trademark) Z / manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) WR series ") and the like are also included in the polyvinyl alcohol resin.

  Anion-modified polyvinyl alcohol is described in, for example, polyvinyl alcohol having an anionic group as described in JP-A-1-206088, JP-A-61-237681 and JP-A-63-307979. Examples thereof include a copolymer of such a vinyl alcohol and a vinyl compound having a water-soluble group, and a modified polyvinyl alcohol having a water-soluble group as described in JP-A-7-285265.

  Nonionic modified polyvinyl alcohol includes, for example, a polyvinyl alcohol derivative in which a polyalkylene oxide group as described in JP-A-7-9758 is added to a part of vinyl alcohol, and JP-A-8-25795. Block copolymer of vinyl compound having hydrophobic group and vinyl alcohol as described, silanol modified polyvinyl alcohol having silanol group, reactivity having reactive group such as acetoacetyl group, carbonyl group, carboxyl group Examples thereof include group-modified polyvinyl alcohol.

  Examples of the cation-modified polyvinyl alcohol include primary to tertiary amino groups and quaternary ammonium groups as described in JP-A No. 61-10383. Polyvinyl alcohol contained therein and obtained by saponifying a copolymer of an ethylenically unsaturated monomer having a cationic group and vinyl acetate. Examples of the ethylenically unsaturated monomer having a cationic group include those described in JP 2012-027288 [0067].

  As ethylene modified polyvinyl alcohol, what is described in Unexamined-Japanese-Patent No. 2009-107324, Unexamined-Japanese-Patent No. 2003-248123, Unexamined-Japanese-Patent No. 2003-342322, Japanese Patent Application No. 2013-206913, etc. can be used, for example. Alternatively, commercially available products such as EXEVAL (trade name: manufactured by Kuraray Co., Ltd.) may be used.

  Examples of the vinyl alcohol-based polymer include EXEVAL (trade name: manufactured by Kuraray Co., Ltd.) and Nichigo G polymer (trade name: manufactured by Nippon Synthetic Chemical Industry Co., Ltd.).

  In addition, the above-mentioned polyvinyl alcohol may be used independently or may be used in combination of 2 or more type.

  The weight average molecular weight of polyvinyl alcohol is preferably 1,000 to 200,000, and more preferably 3,000 to 60,000. In this specification, the value measured by a static light scattering method, gel permeation chromatography (GPC), TOFMASS, or the like is adopted as the value of “weight average molecular weight”. When the weight average molecular weight of the water-soluble polymer is in the above range, it is preferable because application in a wet film forming method is possible and productivity can be improved.

  The content of the water-soluble polymer in the refractive index layer is preferably 5 to 75% by mass and more preferably 10 to 70% by mass with respect to the total solid content of the refractive index layer. When the content of the water-soluble polymer is 5% by mass or more, when the low refractive index layer is formed by a wet film forming method, the transparency of the film surface is disturbed when the coating film obtained by coating is dried. This is preferable because it is possible to prevent the deterioration. On the other hand, when the content of the water-soluble polymer is 75% by mass or less, the content is suitable when metal oxide particles are contained in the low refractive index layer, and the low refractive index layer and the high refractive index layer This is preferable because the refractive index difference can be increased. In addition, in this specification, content of water-soluble polymer is calculated | required from the residual solid content of the evaporation-drying method. Specifically, the optical reflection film is immersed in hot water at 95 ° C. for 2 hours, and the remaining film is removed, and then the hot water is evaporated, and the amount of the obtained solid matter is made the water-soluble high molecular weight. At this time, when one peak is observed in each of the 1700-1800 cm-1, 900-1000 cm-1, and 800-900 cm-1 regions in the IR (infrared spectroscopy) spectrum, the water-soluble polymer is polyvinyl alcohol. It can be determined that

  In the form of the refractive index layer using the water-soluble polymer, the optical reflection layer is formed by using a wet coating method (sequential multilayer coating, simultaneous multilayer coating) (for example, a method described in JP2012-027288A). be able to.

  In addition, as the polymer contained in the refractive index layer, those described in JP-T-2002-509279 (corresponding to US Pat. No. 6,049,419) can be used. Specific examples include, for example, polyethylene naphthalate (PEN) and isomers thereof (for example, 2,6-, 1,4-, 1,5-, 2,7- and 2,3-PEN), polyalkylene terephthalate. (Eg, polyethylene terephthalate (PET), polybutylene terephthalate, and poly-1,4-cyclohexanedimethylene terephthalate), polyimide (eg, polyacrylimide), polyetherimide, atactic polystyrene, polycarbonate, polymethacrylate (eg, Polyisobutyl methacrylate, polypropyl methacrylate, polyethyl methacrylate, and polymethyl methacrylate (PMMA)), polyacrylates (eg, polybutyl acrylate, and polymethyl acrylate), cellulose Derivatives (eg, ethyl cellulose, acetyl cellulose, cellulose propionate, acetyl cellulose butyrate, and cellulose nitrate), polyalkylene polymers (eg, polyethylene (PE), polypropylene (PP), polybutylene, polyisobutylene, and poly (4- Methyl) pentene), fluorinated polymers (eg, perfluoroalkoxy resins, polytetrafluoroethylene, fluorinated ethylene propylene copolymers, polyvinylidene fluoride, and polychlorotrifluoroethylene), chlorinated polymers (eg, polyvinylidene chloride and poly) Vinyl chloride), polysulfone, polyethersulfone, polyacrylonitrile, polyamide, silicone resin, epoxy resin, polyvinyl acetate, polyetheramide, Ionomeric resins, elastomers (e.g., polybutadiene, polyisoprene and neoprene), and polyurethanes. Copolymers such as copolymers of PEN [e.g. (a) terephthalic acid or ester thereof, (b) isophthalic acid or ester thereof, (c) phthalic acid or ester thereof, (d) alkane glycol, (e) cycloalkane glycol ( For example, cyclohexanedimethanol diol), (f) alkanedicarboxylic acid, and / or (g) cycloalkanedicarboxylic acid (eg, cyclohexanedicarboxylic acid) and 2,6-, 1,4-, 1,5-, 2, 7- and / or copolymers with 2,3-naphthalenedicarboxylic acid or esters thereof], copolymers of polyalkylene terephthalates [eg (a) naphthalenedicarboxylic acid or esters thereof, (b) isophthalic acid or esters thereof, ( c) phthalic acid or The ester, (d) alkane glycol, (e) cycloalkane glycol (eg, cyclohexanedimethanol diol), (f) alkane dicarboxylic acid, and / or (g) cycloalkane dicarboxylic acid (eg, cyclohexanedicarboxylic acid); Also suitable are copolymers with terephthalic acid or esters thereof, as well as styrene copolymers (eg styrene-butadiene copolymers and styrene-acrylonitrile copolymers), 4,4-bisbenzoic acid and ethylene glycol. In addition, each layer may each include a blend of two or more of the above polymers or copolymers (eg, a blend of syndiotactic polystyrene (SPS) and atactic polystyrene). In this embodiment, as a preferable combination of polymers forming the high refractive index layer and the low refractive index layer, PEN / PMMA, PET / PMMA, PE / PMMA, PE / polyvinylidene fluoride, PEN / polyvinylidene fluoride, PEN / PET , PEN / polybutylene terephthalate and the like.

  The weight average molecular weight of the polymer contained in the refractive index layer is about 10,000 to 1,000,000, preferably 50,000 to 800,000. In addition, the value measured by gel permeation chromatography (GPC) is employ | adopted for a weight average molecular weight.

  In the refractive index layer, the polymer content is, for example, 30% by mass or more, preferably 50% by mass or more, more preferably 70% by mass or more, based on the total solid content of each refractive index layer. It is.

  In the above form, the optical reflective layer can be formed by melt extrusion. More specifically, for example, as described in JP-T-2002-509279 (corresponding to US Pat. No. 6,049,419), a molten resin obtained by melting a resin is ( Multi-layer) Extrude onto a casting drum from an extrusion die and then cool rapidly. At this time, the resin sheet may be stretched after extrusion cooling of the molten resin. Unlike a method using a solvent such as a coating method or a solution pouring method, the optical reflection layer can be formed without using a solvent by melt extrusion molding. Therefore, forming the optical reflective layer by melt extrusion is advantageous from the viewpoint of production efficiency. The optical reflective film according to the above-described embodiment is one in which an optical reflective layer is formed by multilayer extrusion in which a high refractive index layer containing a first polymer and a low refractive index layer containing a second polymer are simultaneously laminated. It is preferable that

(Metal oxide particles)
The low refractive index layer may contain a metal oxide (particle). By containing metal oxide particles, the refractive index difference between the refractive index layers can be increased, and the reflection characteristics are improved. In the present invention, since the high refractive index layer contains titanium oxide, the difference in refractive index can be further increased when the low refractive index layer contains metal oxide particles. By including metal oxide particles, the number of stacked layers can be reduced and a thin film can be obtained. By reducing the number of layers, productivity can be improved and a decrease in transparency due to scattering at the lamination interface can be suppressed.

  The high refractive index layer may contain other metal oxide particles in addition to titanium oxide.

  As the metal oxide particles, the metal constituting the metal oxide is Li, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Rb, Sr, Y, Nb, Zr, Mo, Ag, Cd, In, Sn, Sb, Cs, Ba, La, Ta, Hf, W, Ir, Tl, Pb, Bi and a rare earth metal A metal oxide which is one kind or two or more kinds of metals can be used.

  As the metal oxide particles used in the low refractive index layer, it is preferable to use silicon dioxide, and it is particularly preferable to use colloidal silica. The metal oxide particles (preferably silicon dioxide) contained in the low refractive index layer preferably have an average particle size of 3 to 100 nm. The average particle size of primary particles of silicon dioxide dispersed in a primary particle state (particle size in a dispersion state before coating) is more preferably 3 to 50 nm, and further preferably 3 to 40 nm. 3 to 20 nm is particularly preferable, and 4 to 10 nm is most preferable. Moreover, as an average particle diameter of secondary particle | grains, it is preferable from a viewpoint with few hazes and excellent visible light transmittance | permeability that it is 30 nm or less. The average particle size of the metal oxide in the low refractive index layer is determined by observing the particles themselves or the cross section or surface of the refractive index layer with an electron microscope and measuring the particle size of 1,000 arbitrary particles. The simple average value (number average) is obtained. Here, the particle diameter of each particle is represented by a diameter assuming a circle equal to the projected area.

  As content of the metal oxide particle in a low-refractive-index layer, it is preferable that it is 5-80 mass% from a viewpoint of refractive index with respect to solid content of a low-refractive-index layer, and is 10-75 mass%. More preferably.

  Colloidal silica is obtained by heating and aging a silica sol obtained by metathesis of sodium silicate with an acid or the like or passing through an ion exchange resin layer. For example, JP-A-57-14091 and JP-A-60- No. 219083, JP-A-60-218904, JP-A-61-20792, JP-A-61-188183, JP-A-63-17807, JP-A-4-93284, JP-A-5-278324, JP-A-6-92011, JP-A-6-183134, JP-A-6-297830, JP-A-7-81214, JP-A-7-101142, JP-A-7- 179029, JP-A-7-137431, and International Publication No. 94/26530. Such colloidal silica may be a synthetic product or a commercially available product. The surface of the colloidal silica may be cation-modified, or may be treated with Al, Ca, Mg, Ba or the like.

  Such colloidal silica may be a synthetic product or a commercially available product. Examples of commercially available products include the Snowtex series (Snowtex OS, OXS, S, OS, 20, 30, 40, O, N, C, etc.) sold by Nissan Chemical Industries.

(Other ingredients)
In addition to the above, each refractive index layer is composed of, for example, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988, and JP-A-62-261476, and JP-A-57-74192. No. 57-87989, No. 60-72785, No. 61-146591, No. 1-95091, No. 3-13376, etc. No. 42993, 59-52689, 62-280069, 61-242871, and JP-A 4-219266, etc., whitening agent, sulfuric acid, phosphoric acid, acetic acid PH adjusters such as citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate, antifoaming agents, lubricants such as diethylene glycol, preservatives, antistatic agents, Various known additives such as DOO agent may contain. The content of these additives is preferably 0.1 to 10% by mass with respect to the solid content of the refractive index layer.

  Alternatively, when each refractive index layer contains a water-soluble polymer, a curing agent can be used to cure the water-soluble polymer. Curing agents include boric acid and its salts, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidylcyclohexane, N, N-diglycidyl-4-glycidyloxyaniline, sorbitol polyglycidyl Ether, glycerol polyglycidyl ether, etc.), aldehyde-based curing agents (formaldehyde, glyoxal, etc.), active halogen-based curing agents (2,4-dichloro-4-hydroxy-1,3,5, -s-triazine, etc.), active Examples thereof include vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), aluminum alum, borax and the like. It is preferable that content of the hardening | curing agent in a refractive index layer is 1-10 mass% with respect to solid content of a refractive index layer.

  Alternatively, each refractive index layer may contain a surfactant for adjusting the surface tension at the time of application. Here, an anionic surfactant, a nonionic surfactant, an amphoteric surfactant, and the like can be used as the surfactant, and an anionic surfactant is more preferable. Preferred compounds include those containing a hydrophobic group having 8 to 30 carbon atoms and a sulfonic acid group or a salt thereof in one molecule. The content of the surfactant in each refractive index layer is preferably 0.01 to 5% by mass with respect to the solid content of the refractive index layer.

<Base material>
The optical reflection film may include a base material. The substrate used is not particularly limited, but is preferably a resin substrate from the viewpoint of flexibility and the like, and may be transparent or opaque. For applications that are required to be transparent with visible light from the viewpoint of design, such as automotive applications, it is preferably transparent in the visible light region. Specifically, the transmittance in the visible light region shown in JIS R3106-1998 is preferably 85% or more, and particularly preferably 90% or more. The base material having the above transmittance or more is advantageous in that the transmittance in the visible light region shown in JIS R3106-1998 is 50% or more (upper limit: 100%) when an infrared shielding film is used. Yes, it is preferable.

  As the resin substrate, polyolefin film (polyethylene, polypropylene, etc.), polyester film (polyethylene terephthalate (PET), polyethylene naphthalate, etc.), polyvinyl chloride, cellulose acetate, etc. can be used, preferably polyester film. . Although it does not specifically limit as a polyester film (henceforth polyester), It is preferable that it is polyester which has the film formation property which has a dicarboxylic acid component and a diol component as main structural components.

  The thickness of the substrate is preferably 10 to 300 μm, particularly preferably 20 to 150 μm. In addition, two substrates may be stacked, and in this case, the type may be the same or different.

  In addition, the optical reflection layer may be formed only on one side of the base material, or may be formed on both sides.

<Other layers>
A conductive layer, antistatic layer, gas barrier layer, easy adhesion layer (adhesive layer), antifouling layer, anti-fouling layer for the purpose of adding further functions under the substrate or on the outermost surface layer opposite to the substrate. Odor layer, droplet layer, slippery layer, hard coat layer, wear-resistant layer, antireflection layer, electromagnetic wave shielding layer, ultraviolet absorption layer, infrared absorption layer, printing layer, fluorescent light emitting layer, hologram layer, release layer, adhesive Functions such as an agent layer, an adhesive layer, an infrared cut layer (metal layer, liquid crystal layer) other than the high refractive index layer and the low refractive index layer, a colored layer (visible light absorption layer), and an intermediate film layer used for laminated glass You may have one or more of the layers. The order of stacking the various functional layers described above is not particularly limited.

  For example, in the specification of attaching an optical reflective film to the indoor side of a window glass (internally attached), an optical reflective layer including at least one unit obtained by laminating the high refractive index layer and the low refractive index layer on the substrate surface, an adhesive A preferred example is a form in which the layers are laminated in the order of the layers, and a hard coat layer is coated on the surface of the substrate opposite to the side where these layers are laminated. Moreover, the order of the pressure-sensitive adhesive layer, the base material, the optical reflection layer, and the hard coat layer may be sufficient, and further, another functional layer, the base material, or an infrared absorber may be included. Moreover, when a preferable example is given also in the specification which affixes the optical reflection film of this invention on the outdoor side of a window glass (outside sticking), it laminates | stacks in order of an optical reflection layer and an adhesive layer on the base-material surface, and also these layers laminate | stack In this configuration, a hard coat layer is coated on the surface of the substrate opposite to the side on which it is applied. As in the case of the inner paste, the order may be the pressure-sensitive adhesive layer, the base material, the optical reflection layer, and the hard coat layer, and it may have another functional layer base material or an infrared absorber. Good.

  The hard coat layer is formed by laminating a cured resin layer containing a resin that is cured by heat, ultraviolet rays, or the like, on the outermost surface on the side opposite to the glass attachment surface as a surface protective layer for enhancing the scratch resistance. Examples of the curable resin include a curable resin described in International Publication No. 2014/010562. Moreover, it is preferable to use a photoinitiator (radical polymerization initiator) for formation of a hard-coat layer. Photopolymerization initiators are used in combination with tertiary amines such as triethanolamine and methyldiethanolamine; photoinitiator assistants such as benzoic acid derivatives such as 2-dimethylaminoethylbenzoic acid and ethyl 4-dimethylaminobenzoate can do. Examples of the photopolymerization initiator include photopolymerization initiators described in International Publication No. 2014/010562. Commercially available photopolymerization initiators may be used, for example, Irgacure (registered trademark) -184, 819, 907, 651, 1700, 1800, 819, 369, 261, DAROCUR-TPO (manufactured by BASF Japan Ltd.), Darocur (Registered trademark) -1173 (manufactured by Merck), Ezacure-KIP150, TZT (manufactured by DKSH Japan), Kayacure (registered trademark) BMS, DMBI (manufactured by Nippon Kayaku Co., Ltd.) and the like. The amount of the photopolymerization initiator used is preferably 0.5 to 30 parts by mass, more preferably 1 to 25 parts by mass with respect to 100 parts by mass of the polymerizable component of the resin.

  In addition, a surfactant can be added to the hard coat layer to impart leveling properties, water repellency, slipperiness, and the like. The type of the surfactant is not particularly limited, and an acrylic surfactant, a silicone surfactant, a fluorine surfactant, or the like can be used. It is preferable that the compounding quantity of surfactant in a hard-coat layer is 0.001-3 mass% with respect to the whole solid content.

  The thickness of the hard coat layer is preferably 0.1 to 20 μm. If it is 0.1 μm or more, the hard coat property tends to be improved, and if it is 20 μm or less, the curl of the hard coat layer is small and the bending resistance tends to be maintained.

  The hard coat layer can be produced by applying the cured resin layer forming composition (coating solution) by wire bar coating, spin coating, or dip coating, and can also be produced by a dry film forming method such as vapor deposition. it can. It does not restrict | limit especially as an adhesive which comprises an adhesive layer, For example, an acrylic adhesive, a silicone adhesive, a urethane adhesive, a polyvinyl butyral adhesive, an ethylene-vinyl acetate adhesive etc. are illustrated. be able to.

  In this pressure-sensitive adhesive layer, as additives, for example, stabilizers, surfactants, ultraviolet absorbers, flame retardants, antistatic agents, antioxidants, thermal stabilizers, lubricants, fillers, coloring, adhesion modifiers, etc. It can also be contained.

  The thickness of the pressure-sensitive adhesive layer is preferably 1 μm to 100 μm, and more preferably 3 to 50 μm. If it is 1 micrometer or more, there exists a tendency for adhesiveness to improve and sufficient adhesive force is acquired. Conversely, if it is 100 μm or less, not only the transparency of the film is improved, but also after the film is attached to the window glass, when it is peeled off, cohesive failure does not occur between the adhesive layers, and the adhesive remains on the glass surface. There is a tendency to disappear.

  The effects of the present invention will be described using the following examples and comparative examples. In the examples, “parts” or “%” may be used, but “parts by mass” or “% by mass” is indicated unless otherwise specified.

<Comparative Example 1: Production of optical reflective film 1-1>
<Preparation of coating solution for low refractive index layer>
A coating solution for a low refractive index layer was prepared as follows. Specifically, 380 parts of colloidal silica (10% by mass) (Snowtex OXS, average particle size of primary particles = 4 to 6 nm; manufactured by Nissan Chemical Industries, Ltd.), 50 parts of boric acid aqueous solution (3% by mass) , 300 parts of polyvinyl alcohol (4% by mass) (JP-45; degree of polymerization: 4500, degree of saponification: 88 mol%; manufactured by NIPPON BI POVAL CO., LTD.), 3 parts of surfactant (5% by mass) ( Softazolin LSB-R (manufactured by Kawaken Fine Chemical Co., Ltd.) was added in this order at 45 ° C. And it finished to 1000 parts with pure water, and prepared the coating liquid for low refractive index layers.

<Preparation of coating solution for high refractive index layer>
After adding 2 parts by mass of pure water to 0.5 parts by mass of 15.0% by mass titanium oxide sol (SRD-W, volume average particle size: 5 nm, rutile titanium dioxide particles, manufactured by Sakai Chemical Co., Ltd.), heating to 90 ° C. did. Subsequently, 0.5 parts by mass of an aqueous silicic acid solution (sodium silicate 4 (manufactured by Nippon Chemical Co., Ltd.) diluted with pure water so that the SiO ₂ concentration becomes 0.5% by mass) was gradually added. A heat treatment at 175 ° C. for 18 hours in an autoclave, followed by cooling and concentrating with an ultrafiltration membrane, thereby a titanium dioxide sol (hereinafter referred to as silica adhering) on which SiO ₂ having a solid content concentration of 6% by mass was adhered. Titanium dioxide sol) (volume average particle size: 9 nm) was obtained.

  48 parts by mass of an aqueous citric acid solution (1.92% by mass) is added to 113 parts by mass of the silica-attached titanium dioxide sol (20% by mass) thus obtained, and ethylene modified polyvinyl alcohol (Kuraray Co., Ltd., EXVAL) is added. RS-2117, degree of saponification: 97.5 to 99 mol%, degree of ethylene modification: 3.0 mol%, degree of polymerization: 1700, viscosity (4%, 20 ° C.): 23.0 to 30.0 (mPa · s) 8 mass%) was added and stirred, and finally 0.4 mass parts of a 5 mass% aqueous solution of surfactant (Softazoline LSB-R, manufactured by Kawaken Fine Chemical Co., Ltd.) was added, and a high refractive index layer was applied. A liquid was prepared.

<Preparation of coating solution for pressure-sensitive adhesive layer>
An adhesive layer coating solution was prepared according to the following formulation.
Composition of adhesive layer coating solution:
Adhesive: N-2147 manufactured by Nippon Synthetic Chemical Industry (solid content 35%) 100 parts BASF UV absorber Tinuvin 477 (solid content 80%) 2.1 parts Isocyanate-based curing agent Coronate L55E manufactured by Nippon Polyurethane Industry (55% solid content) ) 5 parts <Preparation of coating solution for hard coat layer>
73 parts by mass of pentaerythritol tri / tetraacrylate (NK ester (registered trademark) A-TMM-3, manufactured by Shin-Nakamura Chemical Co., Ltd.), 5 parts by mass of Irgacure (registered trademark) 184 (produced by Ciba Japan) 1 part by mass of a silicone surfactant (KF-351A, manufactured by Shin-Etsu Chemical Co., Ltd.), 10 parts by mass of propylene glycol monomethyl ether, 70 parts by mass of methyl acetate, and 70 parts by mass of methyl ethyl ketone were obtained. The obtained mixed solution was filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a coating solution for a hard coat layer.

<Production of optical reflection film>
Resin film (polyethylene terephthalate film having a thickness of 50 μm; Toyobo Co., Ltd.) heated to 45 ° C. while keeping the coating solution for low refractive index layer and the coating solution for high refractive index layer obtained above at 45 ° C. Co., Ltd., Cosmo Shine A4300, with double-sided easy-adhesion layer), the outermost layers are both low-refractive index layers, and the other layers are alternately alternated. A total of 21 layers were simultaneously applied using a slide hopper coating apparatus so that the rate layer was 130 nm in each layer. The confirmation of the mixed region (mixed layer) between layers and the measurement (confirmation) of the film thickness were performed by cutting the laminated film (optical reflective film sample) and cutting the cut surface with an XPS surface analyzer (high refractive index layer material (TiO _2)). ) And the abundance of the low refractive index layer material (SiO ₂ ), it was confirmed that the thickness of each layer described above was ensured.

  Immediately after application, 5 ° C. cold air was blown and set. At this time, even if the surface was touched with a finger, the time until the finger was lost (set time) was 5 minutes. After completion of the setting, warm air of 80 ° C. was blown and dried to form an optical reflective layer as a dielectric multilayer film on the substrate 1. The refractive index of the high refractive index layer was 1.83, and the refractive index of the low refractive index layer was 1.49.

Thereafter, using a micro gravure coater, the hard coat layer coating solution prepared above is applied onto the resin film on the side opposite to the surface where the optical reflective layer is in contact with the resin film, and the constant rate drying section temperature is reduced to 50 ° C. After drying at a rate drying zone temperature of 90 ° C., using an ultraviolet lamp, the illuminance of the irradiated part is 100 mW / cm ² , the irradiation amount is 0.5 J / cm ² , the coating layer is cured, and the dry film thickness is 4 μm. A hard coat layer was formed.

  Further, the pressure-sensitive adhesive layer coating solution prepared above was applied to a 38 μm-thick polyethylene terephthalate substrate (used as a separator) with a gravure coater in a coating amount of 10 μm after drying and dried at 70 ° C. Thus, an adhesive layer was formed, placed so that the dielectric multilayer film of the resin film was in contact with the adhesive layer, and bonded by a roll laminating method.

  Thus, an optical reflection film 1-1 was produced.

<Examples 1 to 6: Production of optical reflection films 1-2 to 7>
In the production of the optical reflective film 1-1, cerium oxide dispersion (NANOBYK (registered trademark) -3810 (manufactured by BYK), volume average particle size 10 nm) is shown in Table 1 with respect to the silica-attached titanium dioxide sol (20% by mass). After adding in the amount shown in (addition amount of cerium oxide to silica-attached titanium dioxide), a citric acid aqueous solution, ethylene-modified polyvinyl alcohol and a surfactant were added to prepare a high refractive index layer coating solution. Optical reflection films 1-2 to 1-7 were prepared in the same manner as the optical reflection film 1-1.

  The color of the film was visually evaluated. Then, the weather resistance evaluation by the below-mentioned xenon light irradiation was performed, and the discoloration suppression effect was evaluated by the color difference ((DELTA) E) from an initial color. In addition, NANOBYK (registered trademark) -3810 (manufactured by BYK) and a volume average particle diameter of 10 nm were used as the cerium oxide dispersion.

(Weather resistance discoloration evaluation)
The separator was peeled off from each optical reflection film and attached to glass by water application to prepare a sample. This sample was irradiated from the glass side with a xenon lamp (Suga Test Machine SX75) at a radiation intensity of 180 W / m ² and then initially with a spectrophotometer (U-4000 type) every 50 hours of irradiation time. The color difference (ΔE) from the color tone of (irradiation 0 hr) was measured, and the time when the color difference exceeded 3.0 was evaluated. When ΔE exceeded 3.0 between measurements, the time when ΔE exceeded 3.0 was calculated on the assumption that the color difference increased in proportion to the irradiation time.

  The results are shown in Table 1.

  As apparent from Table 1, the discoloration of the film was suppressed by adding cerium oxide. Moreover, it turns out that addition in the range of 5-10 vol% with respect to a titanium oxide is preferable from the favorable color tone of a film and being excellent in the discoloration suppression effect.

<Examples 7 to 12: Production of optical reflection films 2-1 to 2-6>
The titanium oxide dispersion used in the production of the optical reflective film 1-1 was heated at 50 ° C., and the heating time was changed to prepare dispersions having volume average particle sizes of 30 nm, 60 nm, and 110 nm. Similarly, the cerium oxide dispersion used in the production of the optical reflection film 1-1 was heated at 50 ° C., and the heating time was changed to prepare dispersions having volume average particle sizes of 20 nm, 60 nm, and 110 nm. Example 1 except that the dispersions having different particle diameters in the combinations shown in Table 2 were mixed, and the dispersions were mixed and then changed to a process of adding an aqueous citric acid solution, ethylene-modified polyvinyl alcohol, and a surfactant. Optical reflective films 2-1 to 2-6 were prepared in the same manner as above.

  The haze and weather resistance discoloration of the optical reflection films 2-1 to 2-6 were evaluated. In addition, all the addition amount of cerium oxide was unified to 5.0 vol% with respect to the titanium oxide particle.

(Haze measurement)
Haze was measured with a haze meter (manufactured by Nippon Denshoku Industries Co., Ltd., NDH2000) using the same sample (sample attached to glass) as the weather resistance discoloration evaluation. The light incident surface was from the glass surface side, the light source of the haze meter was a halogen bulb of 5V9W, and the light receiving portion was a silicon photocell (with a relative visibility filter). The haze was measured at 23 ° C. and 55% RH.

  The results are shown in Table 2.

  As is clear from Table 2, it can be seen that the haze of the film deteriorates rapidly when the particle size of either titanium oxide or cerium oxide exceeds 100 nm. From the viewpoint of haze, good results are obtained with a particle diameter of titanium oxide and cerium oxide of 50 nm or less. Moreover, it turned out that the discoloration inhibitory effect slightly deteriorates as the particle size of cerium oxide becomes large. This is presumably because the UV absorption ability and the ability to suppress self-reduction are reduced by reducing the surface area of the cerium oxide particles.

<Examples 13 to 17: Production of optical reflection films 3-1 to 3-5>
Next, optical films 3-1 to 3-5 were prepared by changing the layer to which cerium oxide was added as shown in Table 3, and the discoloration suppressing effect and haze were evaluated. In addition, all the addition amount of the cerium oxide was unified to 5.0 vol% with respect to all the titanium oxide particles, and it created like Example 1 except having changed the layer added according to the objective.

<Example 13: Production of optical reflection film 3-1>
In the production of the optical reflective film 1-1, the outermost low refractive index layer coating solution closest to the pressure-sensitive adhesive layer is 5 volumes with respect to the total of titanium oxide particles (silica-attached titanium dioxide) contained in the high refractive index layer. % Cerium oxide (solid content) (NANOBYK (registered trademark) -3810 (manufactured by BYK) as a surface-coated cerium oxide dispersion) was added in the same manner as in the optical reflective film 1-1, except that Sample 3-1 Was made.

<Example 14: Production of optical reflection film 3-2>
In the production of the optical reflection film 1-1, each of the low refractive index layer coating liquids other than the outermost low refractive index layer has a low relative to the total of titanium oxide particles (silica-attached titanium dioxide) contained in the high refractive index layer. Each low refractive index layer coating solution so that the total of cerium oxide (solid content) contained in the refractive index layer (NANOBYK (registered trademark) -3810 (manufactured by BYK) as a surface-coated cerium oxide dispersion) is 5% by volume. Sample 3-2 was produced in the same manner as the optical reflective film 1-1 except that cerium oxide was added to the sample.

<Example 15: Production of optical reflection film 3-3>
In the production of the optical reflection film 1-1, the outermost low refractive index layer coating solution closest to the substrate is 5% by volume with respect to the total of titanium oxide particles (silica-attached titanium dioxide) contained in the high refractive index layer. Sample 3-3 was prepared in the same manner as the optical reflective film 1-1 except that cerium oxide (solid content) (NANOBYK (registered trademark) -3810 (manufactured by BYK) as a surface-coated cerium oxide dispersion) was added. Produced.

<Example 16: Production of optical reflection film 3-4>
In the production of the optical reflection film 1-1, the outermost low refractive index layer coating solution on the pressure-sensitive adhesive layer side is 2% by volume with respect to the total of titanium oxide particles (silica-attached titanium dioxide) contained in the high refractive index layer. Cerium oxide (solid content) (NANOBYK (registered trademark) -3810 (manufactured by BYK) as a surface-coated cerium oxide dispersion) was added, and titanium oxide particles (silica-attached titanium dioxide were added to the high refractive index layer coating solution ) Except that 3% by volume of cerium oxide (solid content) (NANOBYK (registered trademark) -3810 (manufactured by BYK) as a surface-coated cerium oxide dispersion) was added to the optical reflective film 1-1. Thus, Sample 3-4 was produced.

<Example 17: Production of optical reflection film 3-5>
In the production of the optical reflection film 1-1, the outermost low refractive index layer coating solution on the pressure-sensitive adhesive layer side is 3% by volume with respect to the total of titanium oxide particles (silica-attached titanium dioxide) contained in the high refractive index layer. Cerium oxide (solid content) (NANOBYK (registered trademark) -3810 (manufactured by BYK) as a surface-coated cerium oxide dispersion) was added, and titanium oxide particles (silica-attached titanium dioxide were added to the high refractive index layer coating solution 2% by volume of cerium oxide (solid content) (NANOBYK (registered trademark) -3810 (manufactured by BYK) as a surface-coated cerium oxide dispersion) was added to the optical reflective film 1-1. Thus, Sample 3-5 was produced.

  The haze and weather resistance discoloration after the weather resistance test of the optical reflection films 3-1 to 3-6 were evaluated. In addition, all the addition amount of cerium oxide was unified to 5.0 vol% with respect to the titanium oxide particle.

  As is apparent from Table 3, it can be seen that the addition (sample 3-1) to the layer closest to the light source has the greatest effect after the addition of the high refractive index layer (sample 1-3). Furthermore, it was found that by adding cerium oxide separately to the high refractive index layer and the layer closest to the light source (samples 3-4 and 3-5), the effect of suppressing discoloration can be increased without haze deterioration. It was. It is estimated that the effect of cutting UV, which is the excitation wavelength of titanium oxide, in the layer closest to the light source, and the effect of UV cut and self-reduction suppression in the titanium oxide layer appear as a synergistic effect.

1 optical reflection film,
2 adhesive layer,
3 optical reflection layer,
4 base material,
5 Hard coat layer,
6 Substrate.

Claims (5)

An optical reflective film having an optical reflective layer including at least one unit obtained by laminating a high refractive index layer containing titanium oxide and a low refractive index layer,
The optical reflective layer comprises cerium oxide;
The optical reflective film, wherein the content of cerium oxide with respect to the total amount of titanium oxide contained in the optical reflective layer is 1 to 30% by volume.   The optical reflective film according to claim 1, wherein the cerium oxide and the titanium oxide have a volume average particle diameter of 1 to 100 nm.   The optical reflection film according to claim 1, wherein at least the high refractive index layer contains the cerium oxide.   The optical reflective film according to claim 3, wherein the outermost layer of the optical reflective layer is a low refractive index layer, and any one of the outermost low refractive index layers contains cerium oxide.   Furthermore, the optical reflection film of Claim 4 which has an adhesive layer and the outermost layer nearest to an adhesive layer contains a cerium oxide.