JP2016057537A - Optical reflection film, method for producing the same and optical reflection body prepared therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an optical reflection film that prevents decrease in reflectance even when used for a long time.SOLUTION: The present invention provides an optical reflection film in which a reflection layer including at least one layer of one unit having a high-refractive-index layer comprising titanium oxide and a low-refractive-index layer comprising silicon oxide is put on a base material. At least one of the unit(s) is subjected to interface peeling preventive treatment.SELECTED DRAWING: None

Description

  The present invention relates to an optical reflection film, a method for producing the same, and an optical reflector using the same.

  Designed to reflect light in a specific wavelength region such as near-infrared, far-infrared, visible light, and ultraviolet light by adjusting the optical characteristics of each layer in an optical reflective film that has a laminated unit in which layers with different refractive indexes are laminated alternately It is known that it can be done.

  Although such an optical reflection film has no restriction | limiting in the use, For example, it can be used conveniently as a metallic glossy tone film, a visible light transmission coloring film, and a heat-shielding film.

  Developments related to the above have been made in various fields. For example, Patent Document 1 discloses a window glass for a building, an in-vehicle glass, and a film, an eyeglass lens, a camera lens, and a display filter that are used by being attached to them. A coating composition for realizing a functional film that selectively reflects or transmits a specific wavelength by multilayer coating on plastic or glass such as the above is disclosed.

JP 2004-123766 A

  However, the conventional optical reflection film has a problem that the reflectance decreases when exposed to, for example, sunlight for a long time.

  Therefore, an object of the present invention is to provide an optical reflection film in which a decrease in reflectance is suppressed even when exposed to sunlight or the like for a long time.

  Moreover, it aims at providing the manufacturing method of such an optical reflection film, and an optical reflector using the same.

  The present inventor has intensively studied to solve the above problems.

  In the process, the mechanism by which the reflectance decreases when exposed to sunlight for a long time was examined.

  As the study progressed, it was found that the optical reflective film had streaks, cracks, or peeling on the surface, which led to a decrease in reflectance. And it also led to the deterioration of the appearance.

  The optical reflective film is usually formed by laminating a reflective layer including at least one unit composed of a high refractive index layer and a low refractive index layer on a substrate. In the present invention, the metal of the high refractive index layer is laminated. Titanium oxide is used as the oxide, and silicon oxide is used as the metal oxide of the low refractive index layer, and at least one of these units is subjected to an interface peeling suppression treatment, so that the appearance of streaks, cracks, peeling, etc. It was found that the decrease was suppressed, and as a result, the reflectance could be improved, and the present invention could be completed.

  ADVANTAGE OF THE INVENTION According to this invention, even if it exposes to sunlight etc. for a long time, the optical reflection film by which the fall of a reflectance is suppressed can be provided.

  Moreover, the manufacturing method of such an optical reflection film and an optical reflector using the same can be provided.

  In the first aspect of the present invention, an optical layer is formed by laminating a reflective layer including at least one unit composed of a high refractive index layer containing titanium oxide and a low refractive index layer containing silicon oxide on a substrate. It is a reflection film, It is an optical reflection film by which the peeling prevention process of the interface is performed to at least one of the said units.

  The second aspect of the present invention includes laminating a reflective layer including at least one unit composed of a high refractive index layer containing titanium oxide and a low refractive index layer containing silicon oxide on a substrate. It is a manufacturing method of an optical reflective film, Comprising: It is a manufacturing method of an optical reflective film which has performing the peeling suppression process of an interface to at least one of the said units.

  A third aspect of the present invention is an optical reflector in which an optical reflective film is provided on at least one surface of a substrate by the first optical reflective film of the present invention or the second production method of the present invention.

  By adopting the above configuration, it is possible to provide an optical reflection film in which a decrease in reflectance is suppressed even when exposed to sunlight or the like for a long time.

  Moreover, the manufacturing method of such an optical reflection film and an optical reflector using the same can be provided.

  Hereinafter, preferred embodiments of the present invention will be described in detail. In the following, when the low refractive index layer and the high refractive index layer are not distinguished from each other, they may be referred to as “refractive index layer” as a concept including both or referring to either of them.

  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%.

[First of the present invention]
In the first aspect of the present invention, an optical layer is formed by laminating a reflective layer including at least one unit composed of a high refractive index layer containing titanium oxide and a low refractive index layer containing silicon oxide on a substrate. It is a reflection film, It is an optical reflection film by which the peeling prevention process of the interface is performed to at least one of the said units.

<Layer structure of optical reflection film>
First, the layer structure of the optical reflection film will be described. The optical reflection film used in the first aspect of the present invention has a basic layer structure that includes at least one unit composed of a high refractive index layer containing titanium oxide and a low refractive index layer containing silicon oxide. A layer is laminated | stacked on a base material. Here, the unit may be formed only on one side of the base material, or may be formed on both sides.

  As described above, when the conventional optical reflective film is exposed to sunlight or the like for a long time, streaks, cracks, or peeling occurs on the surface. The inventor considered that this led to a decrease in reflectance.

  Therefore, at least one layer of one unit composed of a high refractive index layer containing titanium oxide and a low refractive index layer containing silicon oxide is subjected to a peeling suppression treatment, thereby causing streaks, cracks, or peeling on the surface. It was possible to suppress the decrease in reflectance.

  Here, the specific method of the peeling suppression treatment is particularly a method that can suppress peeling at the interface between the high refractive index layer containing titanium oxide and the low refractive index layer containing silicon oxide. Although not limited, preferably, a process for reducing the difference between the temperature of the high refractive index layer in the steady state after light irradiation and the temperature of the low refractive index layer in the steady state after light irradiation is performed.

  More specifically, the present inventor paid attention to titanium oxide of the high refractive index layer in the course of searching for the cause of the occurrence of streaks, cracks, or peeling on the surface. The temperature of the titanium oxide of the high refractive index layer rises when irradiated with sunlight or the like, whereas the silicon oxide of the low refractive index layer does not rise as compared with it. Then, the temperature in each layer in the reflective layer becomes non-uniform, resulting in a difference in the volume change of each layer, resulting in peeling and the like at the interface, which reduces the reflectance and deteriorates the appearance. I thought it would be connected.

  Therefore, according to the first preferred embodiment of the present invention, in the peeling suppression treatment, the temperature of the high refractive index layer is set to X ° C. and the temperature of the low refractive index layer is set to Y ° C. in a steady state after light irradiation. When the following formula 1:

Will be done by satisfying.

  In this way, the difference between the temperature of the high refractive index layer in the steady state after light irradiation and the temperature of the low refractive index layer in the steady state after light irradiation is within 20 ° C. Peeling can be further suppressed, and as a result, a decrease in reflectance and a deterioration in appearance can be further suppressed.

  Here, “steady state” means the following.

  That is, when light derived from a certain light source is irradiated on the optical reflection film, the temperature of each layer increases with the passage of time. However, if irradiation is continued for a certain period of time, the temperature will not increase substantially even if irradiation is continued for a longer time. The state in which the temperature does not substantially increase is defined as “steady state”. Here, “substantially” means, for example, a case of within ± 3 ° C.

  According to a first more preferred embodiment of the present invention, the following formula 2:

Will be done by satisfying.

  By adopting such a configuration, it is possible to further suppress (preferably prevent) cracking and peeling of the surface, thereby further improving the reflectance and further improving the appearance.

  Also, according to the first another more preferred embodiment of the present invention, the following formula 3:

Will be done by satisfying.

  In this way, by setting the temperature of the high refractive index layer in the steady state after light irradiation to be higher than the temperature of the low refractive index layer in the steady state after light irradiation, surface cracking and peeling are suppressed. (Preferably prevention), and thus the reflectance can be improved. However, from the viewpoint of reducing the numerical value of ΔE described later, the following formula 4:

It is better to set. The mechanism is presumed to be because the fluctuation of the film thickness of the high refractive index layer affects the reflection peak in the visible range.

  The first optical reflective film of the present invention is a conductive layer, an antistatic layer, a gas barrier layer, for the purpose of adding further functions under the base material or on the outermost surface layer opposite to the base material. Easy adhesion layer (adhesion layer), antifouling layer, deodorant layer, droplet layer, easy slip 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 layer, adhesive layer, infrared cut layer (metal layer, liquid crystal layer) other than the above high refractive index layer and low refractive index layer, colored layer (visible light absorbing layer), You may have 1 or more of functional layers, such as an intermediate film layer utilized for a laminated glass. The order of stacking the various functional layers described above is not particularly limited.

  For example, in the specification of attaching an optical reflection film to the indoor side of a window glass (internal bonding), an optical reflection layer and an adhesive layer including at least one unit in which the high refractive index layer and the low refractive index layer are laminated on the substrate surface A preferred example is a form in which a hard coat layer is coated on the base material surface on the side opposite to the side on which these layers are laminated. Moreover, the order may be an adhesive layer, a base material, an optical reflection layer, and a hard coat layer, and may further have another functional layer, a base material, or an infrared absorber. Moreover, if 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 will laminate | stack in order of an optical reflection layer and an adhesion layer on the base-material surface, and also these layers will be laminated | stacked. The hard coat layer is coated on the surface of the base material on the side opposite to the coated side. As in the case of the internal bonding, the order may be an adhesive layer, a base material, an optical reflection layer, and a hard coat layer, and may further have another functional layer base material or an infrared absorber. .

  However, even if the functional layer is provided as described above, the difference between the temperature of the high refractive index layer in the steady state after light irradiation and the temperature of the low refractive index layer in the steady state after light irradiation is It is preferable to perform a process of reducing the size.

<Titanium oxide in the high refractive index layer>
In the present invention, the high refractive index layer is formed by applying a coating solution for a high refractive index layer.

  In the present invention, the titanium oxide used in the high refractive index layer is not particularly limited, but a particulate form is assumed. In the present invention, in order to form a transparent and higher refractive index layer having a higher refractive index, the high refractive index layer contains titanium oxide as metal oxide fine particles. In particular, it is preferable to contain rutile (tetragonal) titanium oxide particles because of high refractive index.

  As a method for preparing the aqueous titanium oxide sol, any conventionally known method can be used. For example, JP-A-63-17221, JP-A-7-819, JP-A-9-165218, Refer to the matters described in Kaihei 11-43327, JP-A-63-17221, JP-A-7-819, JP-A-9-165218, JP-A-11-43327, etc. it can.

  As for other methods for producing titanium oxide particles, for example, “Titanium oxide—physical properties and applied technology”, Kiyono Manabu, p. 255-258 (2000), Gihodo Publishing Co., Ltd. The method of the step (2) described in “˜0023” can be referred to. Here, the production method according to the above step (2) refers to at least one basic compound selected from the group consisting of an alkali metal hydroxide or an alkaline earth metal hydroxide. After the step (1) of treating with, the titanium dioxide dispersion obtained comprises a step (2) of treating with a carboxylic acid group-containing compound and an inorganic acid.

  Further, the titanium oxide is preferably in the form of core-shell particles coated with a silicon-containing oxide. Here, the “coating” means a state in which a silicon-containing 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 may be completely covered with a silicon-containing oxide, or a part of the surface of the titanium oxide particles may be covered with a silicon-containing oxide.

  As described above, the titanium oxide of the titanium oxide particles coated with the silicon-containing oxide may be a rutile type or an anatase type, but is more preferably a rutile type. This is because the rutile type titanium oxide particles have lower photocatalytic activity than the anatase type titanium oxide particles, and therefore the weather resistance of the high refractive index layer and the adjacent low refractive index layer is increased, and the refractive index is further increased. Because.

  The coating amount of the silicon-containing oxide is 3 to 30% by mass, preferably 3 to 20% by mass, and more preferably 3 to 10% by mass with respect to titanium oxide serving as the core. This is because when the coating amount is 30% by mass or less, a desired refractive index of the high refractive index layer can be obtained, and when the coating amount is 3% by mass or more, particles can be stably formed.

  As a method of coating the titanium oxide particles with the silicon-containing oxide, a method through heating, filtration and desalting as shown in this example may be used, or a conventionally known method may be applied. For example, the matters described in JP-A-10-158015, JP-A-2000-204301, JP-A-2007-246351 and the like can be referred to.

  By using titanium oxide particles coated with a silicon-containing oxide as the metal oxide of the high refractive index layer, a high refractive index is obtained due to the interaction between the silicon-containing oxide of the shell layer and polyvinyl alcohol described later. The interlayer mixing of the refractive index layer and the low refractive index layer is suppressed.

  The volume average particle diameter of the titanium oxide particles (coated titanium oxide particles) is more preferably 1 to 50 nm, and further preferably 10 to 40 nm. Here, the volume average particle size referred to in the present specification is a method of observing the particles themselves using a laser diffraction scattering method, a dynamic light scattering method, or an electron microscope, or appears on the cross section or surface of the refractive index layer. The particle diameter of 1,000 arbitrary particles is measured by a method of observing the particle image with an electron microscope, and particles having particle diameters of d1, d2,. ..., Ni..., Nk inorganic oxide particles, where the volume average particle diameter mv = {Σ (vi · di)} / {Σ (vi )} Is calculated by weighting the average particle size.

  Furthermore, the titanium oxide particles used for the high refractive index layer are preferably monodispersed. The monodispersion here means that the monodispersity obtained by the following formula is 40% or less. This monodispersity is more preferably 30% or less, and particularly preferably 0.1 to 20%. Within such a range, there is a strong technical effect since the specific concentration of stress during expansion and expansion / contraction is eliminated.

  Further, the content of titanium oxide particles in the high refractive index layer is not particularly limited, but in the high refractive index layer, it is preferably 15 to 90% by volume, more preferably 20 to 85% by volume, More preferably, it is 30-80 volume%, and it is especially preferable that it is 40-80 volume%. By setting it as the said range, it can be set as a favorable optical reflection characteristic. Therefore, according to the first preferred embodiment of the present invention, the content of the titanium oxide is 40 to 80% by volume in the high refractive index layer.

<Silicon oxide in the low refractive index layer>
In the present invention, the low refractive index layer is formed by applying a coating solution for the low refractive index layer.

  In the present invention, specific examples of the silicon oxide used in the low refractive index layer include synthetic amorphous silica and colloidal silica. Of these, colloidal silica, particularly acidic colloidal silica is more preferably used. By using acidic colloidal silica, a water-soluble resin and a stable coating solution can be formed, and the technical effect of improving productivity is obtained.

  The average primary particle size of the silicon oxide in the low refractive index layer (particle size in the dispersion state before coating) is more preferably 1 to 25 nm, further preferably 2 to 20 nm. It is particularly preferred that it is 4 to 10 nm. 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.

  Here, in the present specification, the average primary particle size can be measured from an electron micrograph taken with a transmission electron microscope (TEM) or the like. You may measure by the particle size distribution meter etc. which utilize a dynamic light scattering method, a static light scattering method, etc. When determined from a transmission electron microscope, the average primary particle size is determined simply by observing the particle itself or particles appearing on the cross section or surface of the refractive index layer with an electron microscope, measuring the particle size of 1000 arbitrary particles, It is obtained as an average value (number average). Here, the particle diameter of each particle is represented by a diameter assuming a circle equal to the projected area. In the present invention, a method using a transmission electron microscope is adopted.

  The colloidal silica that can be used in the present invention is also preferably obtained by metathesis of sodium silicate with an acid or the like, or by heating and aging a silica sol obtained by passing through an ion exchange resin layer. JP-A-57-14091, JP-A-60-219083, JP-A-60-219084, 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, Kaihei 7-101142, JP-A-7-179029, JP-A-7-137431, and WO94 / 26530. It is those described in etc..

  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.

  The content of silicon oxide in the low refractive index layer is preferably 20 to 90 mass%, more preferably 30 to 85 mass%, more preferably 40 to 80 mass% based on the total solid content of the low refractive index layer. More preferably, it is mass%. When it is 20% by mass or more, a desired refractive index is obtained, and when it is 90% by mass or less, the coatability is good, which is preferable.

  As described above, the specific method of the peeling suppression treatment is a method capable of suppressing peeling at the interface between the high refractive index layer containing titanium oxide and the low refractive index layer containing silicon oxide. Although not particularly limited, preferably, a process for reducing the difference between the temperature of the high refractive index layer in the steady state after light irradiation and the temperature of the low refractive index layer in the steady state after light irradiation is performed.

  Here, the specific method of such treatment is not particularly limited, but it is preferable that the temperature of the low refractive index layer is made to follow the increase in the temperature of the high refractive index layer. As such a form, according to the first preferred embodiment of the present invention, the peeling suppression treatment is performed by including a temperature increase accelerator in the low refractive index layer. By including a temperature increase accelerator in the low refractive index layer, the temperature increase of the low refractive index layer can follow the temperature increase of the high refractive index layer, and as a result, the temperature difference can be reduced. Further, it is possible to suppress the occurrence of peeling of the interface, a decrease in reflectance, and a deterioration in appearance. Thus, preferably, the temperature rise accelerator is contained only in the low refractive index layer.

  However, the high refractive index layer should not contain a temperature rise accelerator. If the high refractive index layer contains a similar temperature rise accelerator, the temperature in the low refractive index layer is not limited. It is preferable to set the content of the increase promoter to be higher than the content of the temperature increase accelerator in the high refractive index layer.

  In addition, the rate of temperature increase (that is, the rate of temperature increase per unit time) may vary depending on the type of temperature increase accelerator, so the content in each refractive index layer depends on the type of temperature increase accelerator. Accordingly, it may be adjusted as appropriate. Further, if the high-refractive index layer contains a temperature rise accelerator, it is better to adjust the content and the like depending on the type of the temperature rise accelerator.

  Here, according to the 1st more preferable embodiment of this invention, content of the said temperature rise promoter is 0.7-5 mass% with respect to the total solid of the said low refractive index layer. By adopting such a configuration, the difference between the temperature of the high refractive index layer in the steady state after light irradiation and the temperature of the low refractive index layer in the steady state after light irradiation can be significantly reduced. Surface cracking and peeling can be suppressed (preferably prevented), and as a result, the reflectance is improved and the appearance is also improved. More preferably, the content of the temperature rise accelerator is 0.8 to 4.9% by mass, and more preferably 1.1 to 4.8% by mass with respect to the total solid content of the low refractive index layer. %.

  The temperature rise accelerator is not particularly limited as long as it can raise the temperature of the low refractive index layer, but has a triazole skeleton, a benzophenone skeleton, or an imidazole skeleton. With such a configuration, the effects of the present invention can be efficiently achieved.

Further, according to a preferred embodiment of the present invention, the compound for the temperature rise accelerator has a carboxylic acid Na group, a phosphoric acid Na group, a sulfo group or —SO ₃ Na. Such a configuration has a technical effect that water solubility is imparted.

  According to a preferred embodiment of the present invention, the compound having a triazole skeleton is preferably a compound having a benzotriazole skeleton, and examples thereof include a compound represented by the following general formula (1).

In the general formula (1), R ¹ represents a hydrogen atom, a halogen atom or an alkyl group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. As the halogen atom, there can be mentioned fluorine, chlorine, bromine or iodine. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an i-propyl group, a butyl group, a sec-butyl group, a t-butyl group, and a cyclohexyl group. The substitution position of R ¹ is preferably the 4- or 5-position of the benzotriazole skeleton, but the halogen atom and the alkyl group are preferably located at the 4-position. R ² represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an i-propyl group, a butyl group, a t-butyl group, an i-butyl group, and a cyclohexyl group. R ³ represents an alkyl group having 1 to 10 carbon atoms, preferably 1 to ³ carbon atoms, a sulfo group, or —SO ₃ Na.

  According to a preferred embodiment of the present invention, examples of the compound having a benzophenone skeleton include compounds represented by the following general formulas (2) to (3).

In the above general formula (2) and general formula (3),
R ^{4 to} R ⁶ are each independently an alkyl group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, preferably 1 to 6 carbon atoms, a sulfo group, or —SO ₃ Na. is there. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an i-propyl group, a butyl group, a t-butyl group, and a cyclohexyl group. As an alkoxy group, a methoxy group, an ethoxy group, a propoxy group, i-propoxy group, and a butoxy group can be mentioned, for example.

q < ¹ > -q < ³ > is 0-4 each independently, Preferably it is 1-3, More preferably, it is 2.

In general formula (3), preferred combinations of R ⁵ and R ⁶ are each at least two of 1 to 6 alkoxy groups, sulfo groups, and —SO ₃ Na; 1 to 6 alkoxy groups, sulfo groups, and at least two of the -SO ₃ Na.

  According to a preferred embodiment of the present invention, as having an imidazole skeleton,

In the general formula (4),
R ⁷ represents an alkyl group having 1 to 10 carbon atoms, preferably 1 to 3 carbon atoms, a sulfo group or —SO ₃ Na. The substitution position of R ⁷ is not particularly limited.

<Base material>
As the substrate of the first optical reflective film of the present invention, various resin films can be used. Polyolefin film (polyethylene, polypropylene, etc.), polyester film (polyethylene terephthalate (PET), polyethylene naphthalate, etc.), poly Vinyl chloride, cellulose acetate and the like can be used, and a polyester film is preferable. 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 main constituent dicarboxylic acid components include terephthalic acid, isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, diphenylsulfone dicarboxylic acid, diphenyl ether dicarboxylic acid, diphenylethanedicarboxylic acid, Examples thereof include cyclohexane dicarboxylic acid, diphenyl dicarboxylic acid, diphenyl thioether dicarboxylic acid, diphenyl ketone dicarboxylic acid, and phenylindane dicarboxylic acid. Examples of the diol component include ethylene glycol, propylene glycol, tetramethylene glycol, cyclohexanedimethanol, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyethoxyphenyl) propane, bis ( 4-Hydroxyphenyl) sulfone, bisphenol fluorene hydroxyethyl ether, diethylene glycol, neopentyl glycol, hydroquinone, cyclohexanediol and the like. Among the polyesters having these as main constituent components, from the viewpoint of transparency, mechanical strength, dimensional stability, etc., dicarboxylic acid components such as terephthalic acid, 2,6-naphthalenedicarboxylic acid, diol components such as ethylene glycol and 1 Polyester having 1,4-cyclohexanedimethanol as the main constituent is preferred. Of these, polyesters mainly composed of polyethylene terephthalate and polyethylene naphthalate, copolymerized polyesters composed of terephthalic acid, 2,6-naphthalenedicarboxylic acid and ethylene glycol, and mixtures of two or more of these polyesters are mainly used. Polyester as a constituent component is preferable.

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

  The substrate preferably has a visible light region transmittance of 85% or more as shown in JIS R3106-1998, 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.

In addition, the base material using the resin or the like may be an unstretched film or a stretched film.
A stretched film is preferable from the viewpoint of strength improvement and thermal expansion suppression.

  The substrate can be produced by a conventionally known general method. For example, an unstretched substrate that is substantially amorphous and not oriented can be produced by melting a resin as a material with an extruder, extruding it with an annular die or a T-die, and quenching. In addition, the unstretched base material is subjected to a known method such as uniaxial stretching, tenter-type sequential biaxial stretching, tenter-type simultaneous biaxial stretching, tubular-type simultaneous biaxial stretching, or the flow direction of the base material (vertical axis), or A stretched substrate can be produced by stretching in the direction perpendicular to the flow direction of the substrate (horizontal axis). The draw ratio in this case can be appropriately selected according to the resin as the raw material of the substrate, but is preferably 2 to 10 times in the vertical axis direction and the horizontal axis direction.

  In addition, the base material may be subjected to relaxation treatment or off-line heat treatment in terms of dimensional stability. It is preferable that the relaxation treatment is performed in a process from the heat setting in the stretching process of the polyester film to the winding in the transversely stretched tenter or after exiting the tenter. The relaxation treatment is preferably performed at a treatment temperature of 80 to 200 ° C, more preferably a treatment temperature of 100 to 180 ° C. Moreover, it is preferable that the relaxation rate is in the range of 0.1 to 10% in both the longitudinal direction and the width direction, and more preferably, the relaxation rate is 2 to 6%. The relaxed base material is subjected to the following off-line heat treatment to improve heat resistance and to improve dimensional stability.

<Reflective layer>
The reflective layer in the first optical reflective film of the present invention includes at least one unit formed by laminating a high refractive index layer and a low refractive index layer. Preferably, it has a multilayer optical interference film in which a high refractive index layer and a low refractive index layer are alternately laminated on one side or both sides of a substrate. From the viewpoint of productivity, the range of the total number of high refractive index layers and low refractive index layers per side of the substrate is preferably 100 layers or less, more preferably 45 layers or less. The lower limit of the range of the total number of high refractive index layers and low refractive index layers per side of the substrate is not particularly limited, but is preferably 5 layers or more.

  According to a preferred embodiment of the first optical reflective film of the present invention, the number of units is Z / 2 when the total number of the high refractive index layer and the low refractive index layer is Z (provided that “Z / If “2” is not an integer, the value is rounded down).

  The preferred range of the total number of high refractive index layers and low refractive index layers is applicable even when laminated on only one side of the substrate, and when laminated simultaneously on both sides of the substrate. Is also applicable. When laminated on both surfaces of the substrate, the total number of high refractive index layers and low refractive index layers on one surface of the substrate and the other surface may be the same or different.

  In the first optical reflective film of the present invention, the lowermost layer (layer in contact with the substrate) and the outermost layer may be either a high refractive index layer or a low refractive index layer. However, when the low refractive index layer has a layer structure located in the lowermost layer and the outermost layer, the adhesion to the base material of the lowermost layer, the blowing resistance of the uppermost layer, and the hard coat layer to the outermost layer, etc. From the viewpoint of excellent coating properties and adhesiveness, a layer structure in which the lowermost layer and the outermost layer are low refractive index layers is preferable.

  In the first optical reflective film of the present invention, at least one of the units is subjected to peeling prevention treatment, but all units of the reflective layer may be subjected to peeling inhibition treatment, or a part thereof. It may be. In the case where it is a part, it is preferable that 60% or more of the total number of units, more preferably 70% or more, still more preferably 80% or more, and particularly preferably 90% or more is subjected to the peeling prevention treatment.

  Moreover, when it is a part, it is preferable to apply to the one near the outermost surface of the reflective layer. Specifically, preferably 70% or more, more preferably 80% or more of the units subjected to the peeling prevention treatment are (counted) when viewed from the outermost surface of the reflective layer, preferably within ½, More preferably, it exists within 1/3.

  In a preferred embodiment of the first optical reflection film of the present invention, the thickness of each layer may be determined depending on where and how many layers of the refractive index and reflection peak of each layer are to be taken out, except for the outermost layer and the lowermost layer. The thickness of the refractive index layer per layer (thickness after drying) is usually about 20 to 1000 nm, 50 to 500 nm, 800 to 350 nm, or about 100 to 200 nm.

  The thickness of the outermost layer is usually 80 to 250 nm, more preferably 90 to 150 nm.

  When using simultaneous multilayer coating, the thickness of the lowermost layer requires a certain amount of coating solution at the time of coating, which can be adjusted by increasing the thickness of the lowermost layer that does not affect the reflection peak. Usually, it is 300 to 3000 nm, or 1000 to 3000 nm.

  Further, the thickness of the high refractive index layer and the low refractive index layer other than the outermost layer and the lowermost layer may be the same or different, but from the viewpoint of unevenness of drying after coating, Preferably they are the same. Even if they are different, the ratio of the thickness between the high refractive index layer and the low refractive index layer is preferably about 0.6 to 0.99 for the thin layer / thick layer.

  The low refractive index layer in the first optical reflective film of the present invention basically has a lower refractive index. However, normally, the refractive index of the low refractive index layer can be about 1.10 to 1.60, or about 1.30 to 1.50. It is desirable that the high refractive index layer also has a higher refractive index. However, the refractive index of the high refractive index layer can usually be about 1.70 to 2.50, or about 1.90 to 2.20.

  In general, in an optical reflection film, it is possible to increase the reflectance for a desired light beam with a small number of layers by designing a large difference in refractive index between a high refractive index layer and a low refractive index layer. To preferred. In the present invention, the difference in refractive index between at least two adjacent layers (high refractive index layer and low refractive index layer) is preferably 0.3 or more, more preferably 0.35 or more, and most preferably 0. .4 or more. The upper limit is not particularly limited, but is usually 1.4 or less.

  The refractive index difference and the required number of layers can be calculated using commercially available optical design software. For example, in order to obtain a near-infrared reflectance of 90% or more, if the difference in refractive index is smaller than 0.1, it is necessary to laminate 200 layers or more, which not only lowers productivity but also causes scattering at the lamination interface. Larger, less transparent, and very difficult to manufacture without failure.

  When the high refractive index layer and the low refractive index layer are alternately laminated in the optical reflection film, the refractive index difference between the high refractive index layer and the low refractive index layer is within the range of the preferred refractive index difference. Is preferred. However, for example, when the outermost layer is formed as a layer for protecting the film or when the lowermost layer is formed as an adhesion improving layer with the substrate, the above-mentioned preferable refraction is performed with respect to the outermost layer and the lowermost layer. A configuration outside the range of the rate difference may be used.

  The optical reflection film of the present invention can be made into a visible light reflection film or a near-infrared reflection film by changing the 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. Moreover, if the specific wavelength area | region which raises a reflectance is set to an ultraviolet light area | region, it will become an ultraviolet reflective film. When the optical reflective film of the present invention is used for a heat shield film, it may be a (near) infrared reflective (shield) film.

  The total thickness of the optical reflective film of the present invention is preferably 12 μm to 315 μm, more preferably 15 μm to 200 μm, and still more preferably 20 μm to 100 μm.

<Water-soluble polymer>
In the present invention, the refractive index layer preferably contains a water-soluble polymer. Hereinafter, the water-soluble polymer contained in the refractive index layer will be described. The water-soluble polymer contained in the high refractive index layer may be the same as or different from the water-soluble polymer contained in the low refractive index layer.

  Since the solvent of the water-soluble polymer that can be used in the refractive index layer is water, there is also an advantage that it does not cause corrosion, dissolution, or penetration with respect to the base material described later. Furthermore, the water-soluble polymer is preferable because it has high flexibility and thus improves the durability of the optical reflection layer when bent. Hereinafter, the water-soluble polymer suitably used in the optical reflection film of the present invention will be described.

  In the present invention, the water-soluble polymer used in the refractive index layer is not particularly limited, but synthetic water-soluble resins such as polyvinyl alcohols (polyvinyl alcohol or modified polyvinyl alcohol) and polyvinyl pyrrolidones; gelatin, thickening polysaccharides Natural water-soluble polymers such as Among these, it is preferable to use polyvinyl alcohols (polyvinyl alcohol or modified polyvinyl alcohol) from the viewpoint of low oxygen permeability and suppressing the photocatalytic action of titanium oxide contained in the high refractive index layer. Therefore, according to the 1st preferable form of this invention, the said high refractive index layer and the said low refractive index layer further contain polyvinyl alcohol or modified polyvinyl alcohol, respectively.

  Polyvinyl alcohols include, in addition to ordinary polyvinyl alcohol obtained by hydrolysis of polyvinyl acetate, cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol having an anionic group such as a carboxyl group, nonionic group Also included are modified polyvinyl alcohols such as nonionic modified polyvinyl alcohol having a silyl group and silyl modified polyvinyl alcohol having a silyl group.

  Polyvinyl alcohol having a polymerization degree of 200 or more is preferably used, more preferably 1,000 or more, more preferably 1,500 to 5,000, and more preferably 2,000 to 5,000. Are particularly preferably used. This is because when the polymerization degree of polyvinyl alcohol is 200 or more, the coating film does not crack, and when it is 5,000 or less, the coating solution is stabilized. In addition, that the coating solution is stable means that the coating solution is stabilized over time. The same applies hereinafter.

  The saponification degree is preferably 70 to 100 mol%, more preferably 80 to 99.5 mol% from the viewpoint of solubility in water.

  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, in the main chain or side chain of the polyvinyl alcohol. It is 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 trimethyl- (2-acrylamido-2,2-dimethylethyl) ammonium chloride and trimethyl- (3-acrylamido-3,3-dimethylpropyl) ammonium chloride. N-vinylimidazole, N-vinyl-2-methylimidazole, N- (3-dimethylaminopropyl) methacrylamide, hydroxylethyltrimethylammonium chloride, trimethyl- (2-methacrylamidopropyl) ammonium chloride, N- (1, 1-dimethyl-3-dimethylaminopropyl) acrylamide and the like. The ratio of the cation-modified group-containing monomer of the cation-modified polyvinyl alcohol is 0.1 to 10 mol%, preferably 0.2 to 5 mol%, relative to vinyl acetate.

  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 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 a hydrophobic group and vinyl alcohol, silanol-modified polyvinyl alcohol having silanol group, reactive group modification having reactive group such as acetoacetyl group, carbonyl group, carboxyl group Polyvinyl alcohol etc. are mentioned.

  These polyvinyl alcohols may be used alone or in combination of two or more such as the degree of polymerization and the type of modification. As the polyvinyl alcohols, commercially available products or synthetic products may be used. Examples of commercially available products include, for example, PVA-102, PVA-103, PVA-105, PVA-110, PVA-117, PVA-120, PVA-124, PVA-135, PVA-203, PVA-205, PVA -210, PVA-217, PVA-220, PVA-224, PVA-235, etc. Poval (registered trademark, manufactured by Kuraray Co., Ltd.), EXEVAL (registered trademark, manufactured by Kuraray Co., Ltd.), Nichigo G polymer (registered trademark, Japan) Synthetic Chemical Industry Co., Ltd.).

  The content of polyvinyl alcohol in the refractive index layer is preferably from 3 to 70% by mass, more preferably from 5 to 60% by mass, even more preferably from 10 to 50% by mass, particularly preferably based on the total solid content of the refractive index layer. Is 15 to 45% by mass.

(Curing agent)
In the present invention, a curing agent may be used in the refractive index layer. When polyvinyl alcohol is used as the water-soluble polymer, the effect can be exhibited particularly.

  The curing agent that can be used together with polyvinyl alcohol is not particularly limited as long as it causes a curing reaction with polyvinyl alcohol, but boric acid and salts thereof are preferable. Boric acid or a salt thereof refers to an oxygen acid having a boron atom as a central atom and a salt thereof. Specifically, orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid and octabored acid. Examples include acids and their salts. The boric acid and borate as the curing agent may be used as a single aqueous solution or as a mixture of two or more. In the present invention, when boric acid and / or a salt thereof is used, a titanium oxide particle and an OH group of polyvinyl alcohol form a hydrogen bond network, and as a result, an interlayer between the high refractive index layer and the low refractive index layer. Mixing is suppressed and favorable optical properties can be achieved. In particular, when a multilayer coating of a high refractive index layer and a low refractive index layer is applied with a coater, the film surface temperature of the coating film is once cooled to about 15 ° C., and then the set surface coating process is used to dry the film surface. Can express an effect more preferably.

  As the curing agent, in addition to the boric acid and its salts, known ones can be used, and in general, a compound having a group capable of reacting with polyvinyl alcohol or a reaction between different groups possessed by polyvinyl alcohol. It is a compound that promotes and is appropriately selected and used. Specific examples of the curing agent include, for example, epoxy curing agents (diglycidyl ethyl ether, ethylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-diglycidyl cyclohexane, N, N-diglycidyl- 4-glycidyloxyaniline, sorbitol polyglycidyl ether, glycerol polyglycidyl ether, etc.), aldehyde curing agents (formaldehyde, glioxal, etc.), active halogen curing agents (2,4-dichloro-4-hydroxy-1,3,5) , -S-triazine, etc.), active vinyl compounds (1,3,5-trisacryloyl-hexahydro-s-triazine, bisvinylsulfonylmethyl ether, etc.), aluminum alum and the like.

  The total amount of the curing agent used is preferably 10 to 600 mg per 1 g of polyvinyl alcohol (the total amount when polyvinyl alcohol is used), and more preferably 20 to 500 mg.

<Surfactant>
In the present invention, a surfactant may be contained in the refractive index layer. This is because it is preferable from the viewpoint of coatability that the coating liquid for the high refractive index layer and the coating liquid for the low refractive index layer contain a surfactant. Note that the surfactant contained in the high refractive index layer may be the same as or different from the surfactant contained in the low refractive index layer.

  An anionic surfactant, a nonionic surfactant, an amphoteric surfactant, and the like can be used as the surfactant used for adjusting the surface tension at the time of coating, but an amphoteric surfactant is more preferable.

  Examples of amphoteric surfactants preferably used in the present invention include admisulfobetaine type, carboxybetaine type, sulfobetaine type, and imidazolium type. Specific examples of the amphoteric surfactant preferably used in the present invention are shown below. In the present invention, the sulfobetaine type is preferable from the viewpoint of coating unevenness, and examples of the product include LSB-R, LSB (manufactured by Kawaken Fine Chemical Co., Ltd.), Anhitoal HD (manufactured by Kao Corporation), and the like.

  The surfactant content in the refractive index layer and the low refractive index layer is preferably 0.001 to 1% by mass with respect to the total solid content of the high refractive index layer and the low refractive index layer, respectively. More preferably, the content is 0.005 to 0.50% by mass.

[Other additives]
Examples of the first high refractive index layer or low refractive index layer of the present invention include, for example, JP-A-57-74192, 57-87989, 60-72785, 61-146591, Antifading agents, various anionic, cationic or nonionic surfactants described in JP-A-1-95091 and JP-A-3-13376, JP-A-59-42993, JP-A-59-52689 Fluorescent brighteners, sulfuric acid, phosphoric acid, acetic acid, citric acid, sodium hydroxide, potassium hydroxide described in JP-A-62-280069, JP-A-61-228771 and JP-A-4-219266 , Contains pH adjusting agents such as potassium carbonate, antifoaming agents, lubricants such as diethylene glycol, preservatives, antistatic agents, and various known additives such as matting agents. Good. In particular, the addition of citric acid contributes to the stabilization of the coating solution.

  As described above, according to the first aspect of the present invention, it is possible to suppress the occurrence of peeling at the interface of the optical reflection film. And the fall of a reflectance and the deterioration of an external appearance can be suppressed.

  Therefore, in the present invention, an optical layer formed by laminating a reflective layer including at least one unit composed of a high refractive index layer containing titanium oxide and a low refractive index layer containing silicon oxide on a substrate. There is also a method for suppressing peeling at the interface of the at least one unit in a reflective film, the method comprising suppressing temperature peeling by including a temperature increase accelerator in the low refractive index layer of the at least one unit. Is provided.

  The specific description of this embodiment is the same as the above description, and can be applied directly. Note that even if a temperature increase accelerator is included in the low refractive index layer of at least one unit, peeling can be suppressed by including the same in the high refractive index layer. Otherwise, it is not included in the “method for suppressing peeling” in this embodiment.

[Second of the present invention]
The second aspect of the present invention includes laminating a reflective layer including at least one unit composed of a high refractive index layer containing titanium oxide and a low refractive index layer containing silicon oxide on a substrate. It is a manufacturing method of an optical reflective film, Comprising: It is a manufacturing method of an optical reflective film which has performing the peeling suppression process of an interface to at least one of the said units.

  An optical reflective film can be produced by appropriately referring to or combining conventionally known methods except that at least one of the units is subjected to an interface peeling suppression treatment.

  According to the second preferred embodiment of the present invention, it is preferable that a high refractive index layer and a low refractive index layer are alternately applied and dried to form a laminate. Specific examples include: (1) A high refractive index layer coating solution is applied on a substrate and dried to form a high refractive index layer, and then a low refractive index layer coating solution is applied. And then drying to form a low refractive index layer and forming an optical reflective film; (2) After applying a low refractive index layer coating solution on a substrate and drying to form a low refractive index layer, A method of forming a high refractive index layer by applying a coating solution for a high refractive index layer and drying to form an optical reflective film; (3) a coating solution for a high refractive index layer and a low refractive index layer on a substrate; A method of forming an optical reflective film including a high refractive index layer and a low refractive index layer by alternately applying successive coating layers for coating and then drying; (4) coating for a high refractive index layer on a substrate; A liquid and a coating solution for a low refractive index layer are simultaneously applied and dried to form an optical reflective film including a high refractive index layer and a low refractive index layer; Etc., and the like. Among these, the method (4), which is a simpler manufacturing process, is preferable.

  Examples of the coating method include a roll coating method, a rod bar coating method, an air knife coating method, a spray coating method, a curtain coating method, or US Pat. Nos. 2,761,419 and 2,761,791. A slide bead coating method using an hopper, an extrusion coating method, or the like is preferably used.

  The solvent for preparing the coating solution for the high refractive index layer and the coating solution for the low refractive index layer is not particularly limited, but water, an organic solvent, or a mixed solvent thereof is preferable. In the present invention, an aqueous solvent can be used. Compared to the case where an organic solvent is used, the aqueous solvent does not require a large-scale production facility, so that it is preferable in terms of productivity and also in terms of environmental conservation.

  Examples of the organic solvent include alcohols such as methanol, ethanol, 2-propanol and 1-butanol, esters such as ethyl acetate, butyl acetate, propylene glycol monomethyl ether acetate and propylene glycol monoethyl ether acetate, diethyl ether, Examples thereof include ethers such as propylene glycol monomethyl ether and ethylene glycol monoethyl ether, amides such as dimethylformamide and N-methylpyrrolidone, and ketones such as acetone, methyl ethyl ketone, acetylacetone and cyclohexanone. These organic solvents may be used alone or in combination of two or more. From the viewpoint of environment and simplicity of operation, the solvent of the coating solution is preferably an aqueous solvent, more preferably water or a mixed solvent of water and methanol, ethanol, or ethyl acetate, and water is particularly preferable.

  When using a mixed solvent of water and a small amount of an organic solvent, the content of water in the mixed solvent is preferably 80 to 99.9% by mass, based on 100% by mass of the entire mixed solvent, and 90 to 99%. More preferably, it is 5 mass%. Here, by setting it to 80% by mass or more, volume fluctuation due to solvent volatilization can be reduced, handling is improved, and by setting it to 99.9% by mass or less, homogeneity at the time of liquid addition is increased and stable. This is because the obtained liquid properties can be obtained.

  Here, the preparation method of the coating liquid for the high refractive index layer and the coating liquid for the low refractive index layer is not particularly limited, and examples thereof include a method of adding and mixing each component. At this time, the order of addition of the respective components is not particularly limited, and the respective components may be sequentially added and mixed while stirring, or may be added and mixed at one time while stirring.

  In the present invention, when simultaneous multilayer coating is performed, it is preferable that the saponification degrees of polyvinyl alcohol used in the coating solution for the high refractive index layer and the coating solution for the low refractive index layer are different. Different saponification degrees can suppress layer mixing in each step of coating and drying. Although this mechanism is not yet clear, it is thought that mixing is suppressed by the difference in surface tension derived from the difference in saponification degree. In the present invention, the difference in the saponification degree of polyvinyl alcohol used in the coating solution for the high refractive index layer and the coating solution for the low refractive index layer is preferably 3 mol% or more, more preferably 8 mol% or more. That is, the difference between the saponification degree of the high refractive index layer and the saponification degree of the low refractive index layer is preferably 3 mol% or more, and more preferably 8 mol% or more. The upper limit of the difference between the saponification degree of the high refractive index layer and the saponification degree of the low refractive index layer is preferably as high as possible in view of the effect of suppressing / preventing interlayer mixing between the high refractive index layer and the low refractive index layer. Although not limited, it is preferably 20 mol% or less, and more preferably 15 mol% or less.

  The polyvinyl alcohol for comparing the difference in the degree of saponification in each refractive index layer has the highest content in the refractive index layer when each refractive index layer contains a plurality of polyvinyl alcohols (different in saponification degree and polymerization degree). High polyvinyl alcohol. Here, when the phrase “polyvinyl alcohol having the highest content in the refractive index layer” is used, the degree of polymerization is calculated assuming that the polyvinyl alcohol having a saponification degree difference of 3 mol% or less is the same polyvinyl alcohol. Specifically, when polyvinyl alcohol having a saponification degree of 90 mol%, a saponification degree of 91 mol%, and a saponification degree of 93 mol% is contained in the same layer by 10 mass%, 40 mass%, and 50 mass%, respectively. These three polyvinyl alcohols are the same polyvinyl alcohol, and the mixture of these three is polyvinyl alcohol (A) or (B). The saponification degree of this polyvinyl alcohol (A) / (B) is (90 × 0 1 + 91 × 0.4 + 93 × 0.5) /1=91.9 mol%. The “polyvinyl alcohol having a saponification degree difference of 3 mol% or less” is not more than 3 mol% when attention is paid to any polyvinyl alcohol. For example, 90, 91, 92, 94 mol% In the case where the vinyl alcohol is included, since all the polyvinyl alcohols are within 3 mol% when focusing on 91 mol% vinyl alcohol, the same polyvinyl alcohol is obtained.

  When polyvinyl alcohol having a saponification degree different by 3 mol% or more is contained in the same layer, it is regarded as a mixture of different polyvinyl alcohols, and the polymerization degree and the saponification degree are respectively calculated.

  For example, PVA203: 5% by mass, PVA117: 25% by mass, PVA217: 10% by mass, PVA220: 10% by mass, PVA224: 10% by mass, PVA235: 20% by mass, PVA245: 20% by mass, most contained A large amount of PVA is a mixture of PVA 217 to 245 (the difference in the degree of saponification of PVA 217 to 245 is within 3 mol%, which is the same polyvinyl alcohol), and this mixture becomes polyvinyl alcohol (A) or (B). In the mixture of PVA 217 to 245 (polyvinyl alcohol (A) / (B)), the degree of polymerization is (1700 × 0.1 + 2000 × 0.1 + 2400 × 0.1 + 3500 × 0.2 + 4500 × 0.2) / 0. 7 = 3200, and the degree of saponification is 88 mol%.

  When the slide bead coating method is used, the temperature of the coating solution for the high refractive index layer and the coating solution for the low refractive index layer at the time of simultaneous multilayer coating is preferably 25 to 60 ° C, preferably 30 to 45 ° C. A temperature range is more preferred. Moreover, when using a curtain application | coating system, the temperature range of 25-60 degreeC is preferable, and the temperature range of 30-45 degreeC is more preferable.

  The viscosity of the coating solution for the high refractive index layer and the coating solution for the low refractive index layer at the time of simultaneous multilayer coating is not particularly limited. However, when the slide bead coating method is used, the preferable temperature range of the coating liquid is preferably in the range of 5 to 160 mPa · s, more preferably in the range of 60 to 140 mPa · s. Moreover, when using a curtain application | coating system, in the preferable temperature range of said coating liquid, the range of 5-1200 mPa * s is preferable, More preferably, it is the range of 25-500 mPa * s. If it is the range of such a viscosity, simultaneous multilayer coating can be performed efficiently.

  The viscosities at 15 ° C. of the coating solution for the high refractive index layer and the coating solution for the low refractive index layer are each independently preferably 100 mPa · s or more, more preferably 100 to 30,000 mPa · s, and even more preferably. Is 2,500 to 30,000 mPa · s.

  The conditions for the coating and drying method are not particularly limited. For example, in the case of the sequential coating method, first, either the coating solution for the high refractive index layer or the coating solution for the low refractive index layer heated to 30 to 60 ° C. One is coated on a substrate and dried to form a layer, and then the other coating solution is coated on this layer and dried to form a laminated film precursor. Next, the number of units necessary for expressing the desired performance is sequentially applied and dried by the above-described method and laminated to obtain a laminated film precursor. When drying, it is preferable to dry the formed coating film at 30 ° C. or higher. For example, the film surface temperature is preferably 5 to 100 ° C. (preferably 10 to 50 ° C.), and for example, 40 to 60 ° C. warm air is blown for 1 to 5 seconds to dry. As a drying method, warm air drying, infrared drying, and microwave drying are used. Further, drying in a multi-stage process is preferable to drying in a single process, and it is more preferable to set the temperature of the constant rate drying section <the temperature of the rate-decreasing drying section. In this case, the temperature range of the constant rate drying part is preferably 30 to 60 ° C., and the temperature range of the decreasing rate drying part is preferably 50 to 100 ° C.

  Moreover, the conditions of the coating and drying method in the case of simultaneous multilayer coating are as follows. The coating solution for the high refractive index layer and the coating solution for the low refractive index layer are heated to 30 to 60 ° C. After the simultaneous multilayer coating of the layer coating solution and the coating solution for the low refractive index layer, the temperature of the formed coating film is preferably cooled (set) preferably to 1 to 15 ° C. and then dried at 10 ° C. or higher. Is preferred. More preferable drying conditions are conditions in the range of the film surface temperature of 10 to 90 ° C. For example, 40-80 degreeC warm air is sprayed for 1 to 5 seconds, and it dries. Moreover, as a cooling method immediately after application | coating, it is preferable to carry out by a horizontal set system from a viewpoint of the uniformity improvement of the formed coating film.

  Here, the set means that the viscosity of the coating solution is increased by means of lowering the temperature by applying cold air or the like to the coating film, and the fluidity of the substances in each layer and in each layer is reduced or gelled. It means the process to do. A state in which the cold air is applied to the coating film from the surface and the finger is pressed against the surface of the coating film is defined as a set completion state.

  The time (setting time) from the time of application to the completion of setting by applying cold air is preferably within 5 minutes, and more preferably within 2 minutes. Further, the lower limit time is not particularly limited, but it is preferable to take 45 seconds or more. If the set time is too short, mixing of the components in the layer may be insufficient. On the other hand, if the set time is too long, the interlayer diffusion of the inorganic oxide particles proceeds, and the refractive index difference between the high refractive index layer and the low refractive index layer may be insufficient. If the intermediate layer between the high-refractive index layer and the low-refractive index layer is highly elastic, the setting step may not be provided. The set time is adjusted by adjusting the concentration of polyvinyl alcohol and inorganic oxide particles, or adding other components such as various known gelling agents such as gelatin, pectin, agar, carrageenan, and gellan gum. Can be adjusted.

  The temperature of the cold air is preferably 0 to 25 ° C, and more preferably 3 to 10 ° C. The time for which the coating film is exposed to cold air is preferably 10 to 360 seconds, more preferably 10 to 300 seconds, and still more preferably 10 to 120 seconds, although it depends on the transport speed of the coating film.

  What is necessary is just to apply | coat so that the coating thickness of the coating liquid for high refractive index layers and the coating liquid for low refractive index layers may become the thickness at the time of preferable drying as shown above.

[Third invention]
The optical reflective film of the present invention can be applied to a wide range of fields. That is, a third aspect of the present invention is an optical reflector in which the first optical reflective film of the present invention or the optical reflective film produced by the second method of the present invention is provided on at least one surface of a substrate. It is.

  For example, film for window pasting such as heat ray reflecting film that gives heat ray reflection effect, film for agricultural greenhouses, etc. Etc., mainly for the purpose of improving the weather resistance. In particular, it is suitable for a member in which the optical reflective film of the present invention is bonded to a substrate such as glass or a glass substitute resin directly or via an adhesive. In particular, the third aspect of the present invention is very suitable because it is an optical reflector using an optical reflection film that suppresses a decrease in reflectance even when exposed to sunlight or the like for a long time.

<Substrate>
Specific examples of the substrate include, for example, glass, polycarbonate resin, polysulfone resin, acrylic resin, polyolefin resin, polyether resin, polyester resin, polyamide resin, polysulfide resin, unsaturated polyester resin, epoxy resin, melamine resin, and phenol. Examples thereof include resins, diallyl phthalate resins, polyimide resins, urethane resins, polyvinyl acetate resins, polyvinyl alcohol resins, styrene resins, vinyl chloride resins, metal plates, and ceramics. The type of resin may be any of a thermoplastic resin, a thermosetting resin, and an ionizing radiation curable resin, and two or more of these may be used in combination. The substrate can be produced by a known method such as extrusion molding, calendar molding, injection molding, hollow molding, compression molding or the like. The thickness of the substrate is not particularly limited, but is usually 0.1 mm to 5 cm.

  It is preferable that the adhesive layer or the adhesive layer that bonds the optical reflection film and the substrate is disposed on the sunlight (heat ray) incident surface side. Further, it is preferable to sandwich the optical reflection film between the window glass and the substrate because it can be sealed from surrounding gas such as moisture and has excellent durability. Even if the first optical reflecting film of the present invention is installed outdoors or outside the car (for external application), it is preferable because of environmental durability.

  It is preferable that the adhesive layer or the adhesive layer that bonds the optical reflection film and the substrate is installed so that the optical reflection film is on the sunlight (heat ray) incident surface side when bonded to a window glass or the like. Further, when the optical reflection film is sandwiched between the window glass and the base material, it can be sealed from ambient gas such as moisture, which is preferable for durability. Even if the optical reflective film of the present invention is installed outdoors or on the outside of a vehicle (for external application), it is preferable because of environmental durability (particularly light resistance).

  As an adhesive applicable to the present invention, an adhesive mainly composed of a photocurable or thermosetting resin can be used.

  The adhesive preferably has durability against ultraviolet rays, and is preferably an acrylic adhesive or a silicone adhesive. Furthermore, an acrylic adhesive is preferable from the viewpoint of adhesive properties and cost. In particular, since the peel strength can be easily controlled, a solvent system is preferable among the solvent system and the emulsion system in the acrylic adhesive. When a solution polymerization polymer is used as the acrylic solvent-based pressure-sensitive adhesive, known monomers can be used as the monomer.

  Moreover, you may use the polyvinyl butyral resin used as an intermediate | middle layer of a laminated glass, or ethylene-vinyl acetate copolymer type resin. Specifically, plastic polyvinyl butyral [manufactured by Sekisui Chemical Co., Ltd., Mitsubishi Monsanto Co., Ltd.], ethylene-vinyl acetate copolymer [manufactured by DuPont, Takeda Pharmaceutical Co., Ltd., duramin], modified ethylene-vinyl acetate copolymer [Mersen G manufactured by Tosoh Corporation]. In addition, you may add and mix | blend an ultraviolet absorber, an antioxidant, an antistatic agent, a heat stabilizer, a lubricant, a filler, coloring, an adhesion adjusting agent etc. suitably in a contact bonding layer.

  In the present invention, as described above, titanium oxide is used as the metal oxide of the high refractive index layer, and silicon oxide is used as the metal oxide of the low refractive index layer. It is characterized by giving. Therefore, the other features can be designed by appropriately referring to or combining conventional techniques.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In addition, although the display of "part" or "%" is used in an Example, unless otherwise indicated, "mass part" or "mass%" is represented. Unless otherwise specified, each operation is performed at room temperature (25 ° C.).

<Example 1>
(Preparation of coating solution 1 for high refractive index layer)
First, a titanium oxide sol dispersion containing rutile type titanium oxide was prepared.

(Preparation of dispersion of silica-modified titanium oxide particles (rutile type))
A dispersion of silica-modified titanium oxide particles (rutile type) was prepared as follows.

The titanium sulfate aqueous solution was thermally hydrolyzed by a known method to obtain titanium oxide hydrate. The obtained titanium oxide hydrate was suspended in water to obtain 10 L of an aqueous suspension of titanium oxide hydrate (TiO ₂ concentration: 100 g / L). To this, 30 L of an aqueous sodium hydroxide solution (concentration 10 mol / L) was added with stirring, the temperature was raised to 90 ° C., and the mixture was aged for 5 hours. The obtained solution was neutralized with hydrochloric acid, filtered and washed with water to obtain a base-treated titanium compound.

Next, the base-treated titanium compound was suspended in pure water and stirred so that the TiO ₂ concentration was 20 g / L. Under stirring, it was added citric acid in an amount of 0.4 mol% with respect to TiO ₂ weight. The temperature was raised to 95 ° C., concentrated hydrochloric acid was added so that the hydrochloric acid concentration was 30 g / L, and the solution temperature was maintained, followed by stirring for 3 hours. Here, when the pH and zeta potential of the obtained mixed liquid were measured, the pH at 25 ° C. was 1.4, and the zeta potential was +40 mV. Further, when the particle size was measured by Zetasizer Nano (manufactured by Malvern), the volume average particle size was 35 nm and the monodispersity was 16%. Further, the titanium oxide sol solution was dried at 105 ° C. for 3 hours to obtain a particle powder, and X-ray diffraction measurement was performed using JDX-3530 type manufactured by JEOL Datum Co., Ltd. to confirm that the particles were rutile type particles. did.

  1 kg of pure water was added to 1 kg of a 20.0 mass% titanium oxide sol aqueous dispersion containing the rutile-type titanium oxide particles to prepare a 10.0 mass% titanium oxide sol aqueous dispersion.

2 kg of pure water was added to 0.5 kg of the 10.0 mass% titanium oxide sol aqueous dispersion, followed by heating to 90 ° C. Thereafter, 0.1 kg of an aqueous silicic acid solution having a SiO ₂ concentration of 2.0 mass% was gradually added. The resulting dispersion is subjected to heat treatment at 175 ° C. for 18 hours in an autoclave, desalted using ultrafiltration, and further concentrated to contain titanium oxide having a rutile structure coated with SiO ₂ . A dispersion (sol aqueous dispersion) of 20% by mass of silica-modified titanium oxide particles was obtained. At this time, the coating amount of silica was 4% by mass with respect to the titanium oxide particles. Further, when the particle size of silica-modified titanium oxide particles (rutile type) was measured using Zetasizer Nano (manufactured by Malvern), the volume average particle size was 35 nm and the monodispersity was 16%.

  The following constituent materials were sequentially added at 45 ° C., and finally finished to 1000 parts with pure water to prepare a coating solution 1 for high refractive index layer.

(Preparation of coating solution 1 for low refractive index layer) (added amount 0.3%)
10 mass% acidic colloidal silica aqueous solution (Snowtex OXS, average primary particle size: 4 to 6 nm, manufactured by Nissan Chemical Industries, Ltd.) 430 mass parts, 3 mass% boric acid aqueous solution 85 mass parts, pure water 332 mass parts An aqueous solution of 8% by mass of a polyvinyl alcohol which is a water-soluble polymer (PVA-235, polymerization degree: 3500, degree of saponification: 88 mol%, manufactured by Kuraray Co., Ltd.) and 5% by mass of a surfactant solution (Amphithal HD, manufactured by Kao Corporation) 3.0 parts by mass, and further 17.5 parts by mass of 1 mass% benzotriazolyl butylphenol sulfonate aqueous solution at 45 ° C. are added and mixed in this order, and the low refractive index layer Coating solution 1 was prepared.

(Production of reflective layer)
The resulting coating liquid (high refractive index layer coating liquid 1 and low refractive index layer coating liquid 1) is applied to a high refractive index layer coating liquid 1 and low refractive index using a slide hopper coating apparatus capable of coating 15 layers. On the polyethylene terephthalate film (Toyobo A4300, double-sided easy-adhesion layer, length 200 m × width 210 mm) having a thickness of 50 μm, the lowermost layer and the outermost layer are low refractive index layers while keeping the coating liquid 1 for the rate layer at 40 ° C. Other than that, a total of 15 layers were simultaneously applied so that a high refractive index layer and a low refractive index layer were alternately laminated. At this time, the film thickness during drying is adjusted so that the lowermost layer is 1510 nm, the outermost layer is 100 nm, the lower refractive index layers other than the lowermost layer and the uppermost layer are 150 nm, and the high refractive index layers are 150 nm. did.

  Immediately after the application, 5 ° C. cold air was blown to increase the viscosity. After thickening, warm air of 80 ° C. was blown and dried to prepare a multilayer coating product (reflective layer 1) consisting of 15 layers.

  The refractive index of the low refractive index layer was 1.48, and the refractive index of the high refractive index layer was 1.81. The same applies to the following embodiments. The content of silica-modified titanium oxide particles in the high refractive index layer was 52% by volume. The same applies to the following embodiments.

<Example 2>
In the coating solution 1 for the low refractive index layer, the same method as in Example 1 except that the pure water was changed to 262 parts by mass and the 1% by mass of benzotriazolyl butylphenol sulfonate aqueous solution was changed to 70 parts by mass. Thus, a low refractive index coating solution 2 (added amount: 1.2% by mass) was prepared.

  Then, a reflective layer 2 composed of 15 units was produced by the same method as in Example 1.

<Example 3>
In the coating solution 1 for low refractive index layer, the same method as in Example 1 except that the pure water was changed to 157 parts by mass and the 1% by mass benzotriazolyl butylphenol sulfonate aqueous solution was changed to 175 parts by mass. Thus, a low refractive index coating liquid 3 (addition amount 3 mass%) was prepared.

  Then, a reflective layer 3 composed of 15 units was produced in the same manner as in Example 1.

<Example 4>
In the coating solution 1 for a low refractive index layer, the same method as in Example 1 except that pure water was changed to 52 parts by mass and 1% by mass of benzotriazolyl butylphenol sulfonic acid Na aqueous solution was changed to 280 parts by mass. Thus, a low refractive index coating solution 4 (addition amount 4.8% by mass) was produced.

  And the reflection layer 4 which consists of a unit of 15 layers by the method similar to Example 1 was produced.

<Example 5>
Example 1 except that pure water was changed to 11.2 parts by mass and the 1% by mass benzotriazolyl butylphenol sulfonic acid Na aqueous solution was changed to 320.8 parts by mass in the coating solution 1 for the low refractive index layer. A low refractive index coating solution 5 (added amount of 5.5% by mass) was prepared in the same manner as described above.

  And the reflection layer 5 which consists of a unit of 15 layers was produced by the method similar to Example 1. FIG.

<Example 6>
In the coating solution 1 for the low refractive index layer, the low refractive index was changed in the same manner as in Example 1 except that pure water was changed to 157 parts by mass and 1% by mass of phenylbenzimidazolesulfonic acid was changed to 175 parts by mass. Coating solution 6 (addition amount 3% by mass) was prepared.

  Then, a reflective layer 6 composed of 15 layer units was produced in the same manner as in Example 1.

<Example 7>
In the coating solution 1 for the low refractive index layer, the low refractive index coating solution was prepared in the same manner as in Example 1 except that pure water was changed to 157 parts by mass and 1% by mass of benzophenone 4 was changed to 175 parts by mass. 7 (addition amount 3 mass%) was produced.

  Then, a reflective layer 7 composed of 15 layer units was produced in the same manner as in Example 1.

<Example 8>
In the coating solution 1 for the low refractive index layer, the low refractive index coating solution was prepared in the same manner as in Example 1 except that pure water was changed to 157 parts by mass and 1% by mass of benzophenone 9 was changed to 175 parts by mass. 8 (addition amount 3 mass%) was produced.

  Then, a reflective layer 8 composed of 15 layer units was produced in the same manner as in Example 1.

<Comparative Example 1>
A reflective layer 9 consisting of 15 layers was prepared in the same manner as in Example 1 except that the low refractive index layer coating solution 1 was prepared without adding an aqueous solution of sodium benzotriazolylbutylphenol sulfonate. .

<Comparative Example 2>
A coating solution 2 for a high refractive index layer was prepared by adding 105 parts of a benzotriazolyl butylphenol sulfonic acid Na aqueous solution to the coating solution 1 for a high refractive index layer.

  Using the coating solution 2 for high refractive index layer, a reflective layer 10 composed of 15 units was produced in the same manner as in Example 3.

<Temperature measurement>
(Measurement of the temperature of the high refractive index layer)
The coating solution for the high refractive index layer used in each example and each comparative example was applied as a single layer on PET so as to have a film thickness of 5 μm, and xenon light (7.5 x super-xenon weather meter SX75) 180 mw / cm ² ), and after 30 minutes, the temperature of each high refractive index layer was measured with a reflection thermometer.

(Measurement of temperature of low refractive index layer)
The temperature of each low refractive index layer was measured in the same manner as the measurement of the temperature of the high refractive index layer, except that the high refractive index layer coating solution was changed to the low refractive index layer coating solution.

<Weather resistance test>
Using the 7.5 kW super xenon weather meter SX75, the temperature in the tank was set to 30 ° C., and xenon light (180 mw / cm ² ) was set to 100 for each reflective layer prepared in each example and each comparative example. Irradiated for a period of time (20 minutes in rain mode, 100 minutes in sunny mode).

<ΔE>
100 W / m using a xenon weather meter (manufactured by Suga Test Instruments Co., Ltd .; emits light very close to sunlight) on each reflective layer produced in each example and each comparative example under the conditions of 30 ° C. and 60% RH. The sample was exposed to xenon light of intensity ² for 2000 hours, and the color difference (ΔE) was calculated from the difference in transmitted light before and after exposure. In addition, the transmitted light of the sample before and after exposure was evaluated by the transmittance in a 200 to 2000 nm region of a spectrophotometer U-4000 type (using an integrating sphere, manufactured by Hitachi, Ltd.). The results are shown in Table 1. A smaller value of ΔE means that the degree of coloring due to exposure to xenon light is smaller.

<Appearance evaluation>
In order to evaluate the appearance of each optical shielding film after the weather resistance test, the appearance of the reflective layer produced in each example and each comparative example was evaluated using an optical microscope (enlarged 20 times).

  Specifically, the appearance was evaluated by magnifying 20 times with an optical microscope.

  In addition, the meaning of the symbol in Table 1 is as follows.

  A: No cracking or peeling on the surface.

  ○: No cracking or peeling on the surface, but streaks are visible in some areas.

  X: The surface is cracked and peeled off.

<Reflectance>
In order to evaluate the shielding performance of each optical shielding film after the weather resistance test, a spectrophotometer (using an integrating sphere, manufactured by Hitachi, Ltd., U-4000 type) was used, and each optical shielding film was attached to 3 mm glass. The transmittance in a region of 300 nm to 2000 nm from the glass side was measured. The reflectance at 800 to 1100 nm was measured, and the infrared reflectance% was evaluated using the transmittance value of the peak having the highest reflectance.

<Discussion>
As can be seen from the above results, the optical reflective films of the examples are superior to the optical reflective films of the comparative examples from the viewpoints of ΔE, appearance evaluation, and reflectance. Here, when Examples 1 to 4 and 6 to 8 are compared, Examples 2 to 4 and 6 to 8 are more excellent than Example 1 in terms of ΔE, appearance evaluation, and reflectance. I understand that. This is presumed to be because the temperature difference in the latter embodiment is 15 ° C. or less. Moreover, when Example 3 is compared with Example 5, Example 3 is more superior in terms of appearance evaluation and reflectance. This is presumed to be because in Example 3, the temperature of the high refractive index layer is high in the low refractive index layer even at the same temperature difference. On the other hand, Example 5 is superior in terms of ΔE.

Claims (13)

An optical reflective film, wherein a reflective layer comprising at least one unit composed of a high refractive index layer containing titanium oxide and a low refractive index layer containing silicon oxide is laminated on a substrate,
An optical reflective film in which at least one of the units is subjected to an interface peeling inhibiting treatment. The peeling suppression treatment is
When the temperature of the high refractive index layer is X ° C. and the temperature of the low refractive index layer is Y ° C. in a steady state after light irradiation, the following formula 1:
The optical reflection film according to claim 1, wherein the optical reflection film is formed by satisfying The peeling suppression treatment is
Following formula 2:
The optical reflection film according to claim 2, which is performed by satisfying The peeling suppression treatment is
Formula 3 below:
The optical reflection film according to claim 2, wherein the optical reflection film is formed by satisfying the above.   The optical reflection film of any one of Claims 1-4 which the said peeling suppression process performs by including a temperature rise promoter in a low refractive index layer.   The optical reflection film according to claim 5, wherein the content of the temperature increase accelerator in the low refractive index layer is greater than the content of the temperature increase accelerator in the high refractive index layer.   The optical reflective film according to claim 6, wherein the content of the temperature increase accelerator in the low refractive index layer is 0.7 to 5 mass% with respect to the total solid content of the low refractive index layer.   The optical reflection film according to any one of claims 1 to 7, wherein the high refractive index layer and the low refractive index layer each further contain polyvinyl alcohol or modified polyvinyl alcohol.   The optical reflective film according to any one of claims 1 to 8, wherein a content of the titanium oxide is 40 to 80% by volume in the high refractive index layer.   The light reflection film according to any one of claims 5 to 9, wherein the temperature increase accelerator has a triazole skeleton, a benzophenone skeleton, or an imidazole skeleton. A method for producing an optical reflective film, comprising: laminating a reflective layer including at least one unit composed of a high refractive index layer containing titanium oxide and a low refractive index layer containing silicon oxide on a substrate. There,
A method for producing an optical reflective film, comprising subjecting at least one of the units to an interface peeling suppression treatment.   An optical reflector formed by providing the optical reflective film according to any one of claims 1 to 10 or the optical reflective film produced by the method according to claim 11 on at least one surface of a substrate. The at least one of the above-mentioned optical reflective films, wherein a reflective layer including at least one unit composed of a high refractive index layer containing titanium oxide and a low refractive index layer containing silicon oxide is laminated on a substrate. A method for suppressing the separation of the interface between two units,
A method for suppressing peeling, comprising including a temperature increase accelerator in the low refractive index layer of the at least one unit.