JP7679191B2 - Resin film, method for producing resin film, and display device - Google Patents

Description

The present invention relates to a resin film, etc. More specifically, it relates to a resin film, etc. that is provided on the surface of the display means of a display device.

Display devices such as liquid crystal displays (LCDs) and plasma displays (PDPs) are known. Display devices such as electroluminescence displays (ELDs) and field emission displays (FEDs) are also known. An anti-reflection film or an anti-glare film having a low refractive index layer is usually provided on the image display surface of these display devices. The low refractive index layer suppresses reflections of the viewer and the viewer's background.
The low refractive index layer is usually provided on the outermost surface of the anti-reflection film, and the light reflected from the low refractive index layer and the interface between the low refractive index layer and the lower layer cancel each other out, thereby reducing the reflected light and suppressing glare.
On the other hand, as displays become thinner, for example in liquid crystal displays, the distance between the display surface and the backlight becomes very narrow, which has resulted in a demand for the addition of heat insulation properties to block heat generated from the backlight.

Patent Document 1 discloses an optical component for plasma displays. This optical component for plasma displays has a film and an adhesive layer formed on one side of the film. The film has at least an electromagnetic wave shielding function, a near-infrared ray cutting function, and an anti-reflection function. The infrared ray cutting layer is provided on the opposite side of the anti-reflection layer via the substrate, and has a thickness of 5 μm to 30 μm. Furthermore, the film has a tensile strength of 100 N/25 mm width or more, and an adhesive strength of 3.0 N/25 mm width or more.

Patent Document 2 discloses a near-infrared absorbing material. The near-infrared absorbing material is provided with a near-infrared absorbing layer having a thickness of 2 μm to 20 μm on one side of a transparent resin film via a first interference layer. The near-infrared absorbing material has a maximum difference in the amplitude of reflectance at light wavelengths of 500 to 650 nm of 1% or less. The near-infrared absorbing material further includes a second interference layer, a hard coat layer, and an anti-reflection layer consisting of a high refractive index layer and a low refractive index layer. These are provided in order from the transparent resin film side on the other side of the transparent resin film on which the near-infrared absorbing layer is not provided. The near-infrared absorbing material is used by attaching the near-infrared absorbing layer side to a display screen such as a plasma display panel.

Patent document 3 discloses a front filter for plasma displays. This front filter has a film having one or more functional layers and an adhesive layer formed on one side of the film. The film has a substrate and at least one of the following functions: electromagnetic wave shielding, near-infrared blocking, anti-reflection, and color correction. This front filter has a heat dissipation function and/or heat shielding function. The near-infrared blocking layer is provided on the opposite side of the substrate to the anti-reflection layer, and has a thickness of 5 μm to 30 μm.

JP 2005-242227 A JP 2006-47599 A JP 2005-243509 A

In order to provide thermal insulation, a heat-shielding layer containing particles having a heat-shielding function or particles having a heat-dissipating function may be introduced into the resin film. However, such particles generally have a high refractive index. When a heat-shielding layer containing such particles is introduced into the resin film, the optical interference behavior within the film becomes complicated. It is likely to be difficult to control optical properties such as reflectance. In addition, the thickness of the resin film may be shifted, and the color change may become large when the resin film is observed from an oblique angle, which may impair the appearance.
In addition to the anti-reflection film, there is also a method of introducing a separate heat shielding/heat dissipation film. However, in this case, the heat shielding effect is not sufficient. In addition, it is likely to increase the thickness and cost of the display device.
An object of the present invention is to provide a resin film or the like that can achieve both optical properties and heat insulation properties.

The resin film of the present invention has a heat shielding layer, a low refractive index layer, and an adjacent layer. The heat shielding layer has a thickness of 300 nm or more and 1500 nm or less and shields heat. The low refractive index layer has a refractive index lower than that of the heat shielding layer. The adjacent layer is adjacent to the heat shielding layer, is a layer other than the low refractive index layer, and has a refractive index difference with the heat shielding layer of 0.04 or less.
Here, the low refractive index layer can be provided on the opposite side of the heat shield layer from the adjacent layer.
The adjacent layer may also be a hard coat layer.
Additionally, the hardcoat layer may contain particles that increase the refractive index of the hardcoat layer.
And, the particles may be at least one of zirconium oxide, aluminum oxide, titanium oxide, and tin oxide.
Furthermore, a high refractive index layer having a refractive index higher than that of the low refractive index layer may be further provided between the heat shield layer and the low refractive index layer.
Furthermore, the hard coat layer, the heat shield layer, the high refractive index layer and the low refractive index layer may be laminated in this order toward the front surface side.
The heat shield layer may include at least one of an infrared absorbing material and an infrared reflective material. The infrared absorbing material is a material that absorbs infrared rays. The infrared reflective material is a material that reflects infrared rays.
The infrared reflective material may be at least one of indium-containing tin oxide particles, antimony-containing tin oxide particles, and phosphorus-containing tin oxide particles.
Furthermore, the thermal barrier layer contains at least one of indium-containing tin oxide particles, antimony-containing tin oxide particles, and phosphorus-containing tin oxide particles, and may contain these particles in an amount of 50 mass % to 95 mass % of the total mass of the thermal barrier layer.

Furthermore, the method for producing a resin film of the present invention includes a heat shielding layer producing step, a low refractive index layer producing step, and an adjacent layer producing step. The heat shielding layer producing step produces a heat shielding layer having a thickness of 300 nm or more and 1500 nm or less for blocking heat. The low refractive index layer producing step produces a low refractive index layer having a refractive index lower than that of the heat shielding layer. The adjacent layer producing step produces an adjacent layer that is adjacent to the heat shielding layer, is a layer other than the low refractive index layer, and has a refractive index difference with the heat shielding layer of 0.04 or less.
Here, the low refractive index layer can be provided on the opposite side of the heat shield layer from the adjacent layer.
The adjacent layer may also be a hard coat layer.

The display device of the present invention comprises a display means for displaying an image, and the above-mentioned resin film provided on the surface of the display means.
The optical member of the present invention includes a substrate and the above-described resin film provided on the substrate.
Furthermore, the polarizing member of the present invention comprises a polarizing means for polarizing light, and the above-mentioned resin film provided on the polarizing means.

The present invention provides a resin film that can achieve both optical properties and heat insulation properties.

1A is a diagram illustrating a display device to which the present embodiment is applied, and FIG. 1B is a cross-sectional view taken along line Ib-Ib in FIG. 1A, illustrating an example of the configuration of a liquid crystal panel to which the present embodiment is applied. FIG. 2 is a diagram showing a substrate, a hard coat layer, a heat shield layer, a high refractive index layer, and a low refractive index layer. FIG. 13 is a diagram showing reflectance when the difference in refractive index between a hard coat layer and a heat shield layer is changed. FIG. 4 is a diagram showing a case where a high refractive index layer and a low refractive index layer are further added to the case of FIG. 3. 3A is a flow chart showing a method for producing a resin film having a layered structure as shown in Fig. 2. FIG. 3B is a flow chart explaining a method for producing a hard coat layer, a heat shield layer, a high refractive index layer, and a low refractive index layer. FIG. 13 is a diagram showing a configuration in which a hard coat layer and a thermal barrier layer are formed at the same time. 7 is a flowchart showing a method for producing a resin film having the structure shown in FIG. 6. 4(a) to 4(c) are diagrams showing a method for forming a thermal barrier adjacent layer. FIG. 1 is a diagram showing a pencil hardness measuring device for measuring pencil hardness.

The following is a detailed description of the embodiment of the present invention. Note that the present invention is not limited to the embodiment described below. Furthermore, various modifications can be made within the scope of the gist of the invention. Furthermore, the drawings used are for the purpose of explaining the present embodiment, and do not represent the actual size.

<Explanation of the display device>
FIG. 1A is a diagram illustrating a display device 1 to which the present embodiment is applied.
The display device 1 shown in the figure is, for example, a liquid crystal display for a PC (Personal Computer), a liquid crystal television, etc. The display device 1 displays an image on a liquid crystal panel 1a.

<Description of Liquid Crystal Panel 1a>
FIG. 1B is a cross-sectional view taken along line Ib-Ib in FIG. 1A, showing an example of the configuration of a liquid crystal panel 1a to which this embodiment is applied.
The liquid crystal panel 1a is an example of a display means for displaying an image. The liquid crystal panel 1a of the present embodiment is, for example, a VA type liquid crystal panel. The illustrated liquid crystal panel 1a has a backlight 11 and a polarizing film 12a. The liquid crystal panel 1a also has a retardation film 13a, a liquid crystal 14, a retardation film 13b, and a polarizing film 12b. The liquid crystal panel 1a also has a substrate 15, a hard coat layer 16, a heat shielding layer 17, a high refractive index layer 18, and a low refractive index layer 19. These are laminated in this order toward the front side. In the following, when the polarizing film 12a and the polarizing film 12b are not distinguished from each other, they may be simply referred to as the polarizing film 12. When the retardation film 13a and the retardation film 13b are not distinguished from each other, they may be simply referred to as the retardation film 13. In the present embodiment, the substrate 15, the hard coat layer 16, the heat shielding layer 17, the high refractive index layer 18, and the low refractive index layer 19 are examples of a resin film. Hereinafter, the substrate 15, the hard coat layer 16, the heat shielding layer 17, the high refractive index layer 18, and the low refractive index layer 19 may be collectively referred to as a resin film.

The backlight 11 irradiates light onto the liquid crystal 14. The backlight 11 is, for example, a cold cathode fluorescent lamp or a white LED (Light Emitting Diode).
The polarizing film 12a and the polarizing film 12b are an example of a polarizing means for polarizing light. The polarizing film 12a and the polarizing film 12b have polarizing directions perpendicular to each other. The polarizing film 12a and the polarizing film 12b each have a resin film in which iodine compound molecules are contained in polyvinyl alcohol (PVA), for example. This is sandwiched and bonded between resin films made of triacetylcellulose (TAC). The inclusion of iodine compound molecules polarizes light.

The phase difference film 13 compensates for the viewing angle dependency of the liquid crystal panel 1a. The polarization state of the light transmitted through the liquid crystal 14 changes from linearly polarized light to elliptically polarized light. For example, when black is displayed, the liquid crystal panel 1a appears black when viewed vertically. On the other hand, when the liquid crystal panel 1a is viewed obliquely, retardation of the liquid crystal 14 occurs. In addition, the axis of the polarizing film 12 is no longer 90°. This causes light leakage, resulting in whitening and reduced contrast. In other words, the liquid crystal panel 1a has a viewing angle dependency. The phase difference films 13a and 13b have the function of returning this elliptically polarized light to linearly polarized light. As a result, the phase difference films 13a and 13b can compensate for the viewing angle dependency of the liquid crystal panel 1a.

A power source (not shown) is connected to the liquid crystal 14, and when a voltage is applied from the power source, the alignment direction of the liquid crystal 14 changes, thereby causing the liquid crystal 14 to control the light transmission state.
In the case of a VA type liquid crystal panel, when no voltage is applied to the liquid crystal 14 (voltage OFF), the liquid crystal molecules are aligned vertically in the figure. When light is irradiated from the backlight 11, the light first passes through the polarizing film 12a and becomes polarized light. The polarized light then passes through the liquid crystal 14 as is. Furthermore, the polarizing film 12b blocks this polarized light because it has a different polarization direction. In this case, a user looking at the liquid crystal panel 1a cannot see this light. In other words, when no voltage is applied to the liquid crystal 14, the color of the liquid crystal is "black."

On the other hand, when the maximum voltage is applied to the liquid crystal 14, the liquid crystal molecules are aligned in the horizontal direction in the figure. The polarized light that passes through the polarizing film 12a is rotated by 90 degrees by the action of the liquid crystal 14. Therefore, the polarizing film 12b does not block this polarized light, but transmits it. In this case, a user looking at the liquid crystal panel 1a can see this light. That is, when the maximum voltage is applied to the liquid crystal 14, the color of the liquid crystal becomes "white". The voltage can also be between the voltage OFF and the maximum voltage. In this case, the liquid crystal 14 is in a state between the up-down direction in the figure and the vertical direction relative to the up-down direction in the figure. That is, the liquid crystal 14 is aligned in an oblique direction that intersects both the up-down direction and the vertical direction. In this state, the color of the liquid crystal becomes "gray". Therefore, by adjusting the voltage applied to the liquid crystal 14 between OFF and the maximum voltage, intermediate gradations can be expressed in addition to black and white. This allows an image to be displayed.
Although not shown, a color image can also be displayed by using a color filter.

FIG. 2 is a diagram showing a substrate 15, a hard coat layer 16, a heat shielding layer 17, a high refractive index layer 18, and a low refractive index layer 19.
Here, in the figure, the upper side is the front side of the liquid crystal panel 1a, and the lower side is the inside side of the liquid crystal panel 1a.

The substrate 15 is a support for forming the hard coat layer 16, the heat shielding layer 17, the high refractive index layer 18, and the low refractive index layer 19. The substrate 15 is preferably a transparent substrate having a total light transmittance of 85% or more. For example, the substrate 15 is made of the above-mentioned triacetylcellulose (TAC). The substrate 15 is not limited to this, and polyethylene terephthalate (PET) or the like can also be used. However, in this embodiment, triacetylcellulose (TAC) can be more preferably used. The substrate 15 has a thickness of, for example, 20 μm or more and 200 μm or less.

The hard coat layer 16 is a functional layer for preventing the liquid crystal panel 1a from being scratched. The hard coat layer 16 includes a binder 161 as a base material mainly composed of resin. The hard coat layer 16 also includes metal oxide particles 162 as particles for increasing the refractive index of the hard coat layer 16.
The binder 161 is not particularly limited as long as it has excellent light transmission and has a strength appropriate for the intended use when used as a resin film. For example, the same binder as that exemplified for the low refractive index layer 19 described later can be used.
The metal oxide particles 162 are at least one of zirconium oxide (zirconium oxide), aluminum oxide (aluminum oxide), titanium oxide (titanium oxide), and tin oxide (tin oxide), which improves the hard coat properties of the hard coat layer 16 and increases the refractive index.
Furthermore, a conductive substance may be added to the hard coat layer 16. The conductive substance may be, for example, metal fine particles or a conductive polymer. More specifically, the conductive substance may be, for example, tin oxide doped with antimony (Sb), phosphorus (P), or indium (In) (indium-containing tin oxide (ITO)), an ionic liquid containing a fluorine-based anion or an ammonium salt, a conductive polymer such as PEDOT/PSS, or a carbon nanotube. The conductive substance may be added not only to one type, but also to two or more types. This reduces the surface resistance of the hard coat layer 16, and can provide the hard coat layer 16 with an antistatic function.

The heat shielding layer 17 is a functional layer for blocking heat. That is, the heat shielding layer 17 has a heat shielding property and a function of blocking heat from the backlight 11 and the like.
The heat shield layer 17 includes a binder 171 as a base material mainly composed of resin. The binder 171 is not particularly limited as long as it has excellent light transmission and has a strength according to the application when used as a resin film. For example, the same binder as exemplified in the low refractive index layer 19 described later can be used.
The heat shielding layer 17 also includes heat shielding particles 172 having heat shielding properties. The heat shielding particles 172 include, for example, at least one of an infrared absorbing material and an infrared reflecting material. The infrared absorbing material is a material that absorbs infrared rays. The infrared reflecting material is a material that reflects infrared rays. By absorbing or reflecting infrared rays, heat shielding properties can be imparted.
Examples of infrared absorbing materials include phthalocyanine dyes, quinone compounds, and azo compounds. Examples of infrared reflecting materials include indium-containing tin oxide (ITO: tin-doped indium oxide) particles, antimony-containing tin oxide (ATO: antimony-doped tin oxide) particles, phosphorus-containing tin oxide (PTO: phosphorus-doped tin oxide) particles, and silver nanoparticles. The heat shield layer 17 preferably contains at least one of these. The heat shield layer 17 preferably contains at least one of these particles in an amount of 50% by mass or more and 95% by mass or less with respect to the total mass of the heat shield layer 17.
If the content of these particles is less than 50% by mass, the infrared reflecting/absorbing ability is likely to be insufficient, whereas if the content of these particles is more than 95% by mass, the light transmittance is likely to decrease and the film strength of the formed film is likely to decrease.

The heat shielding particles 172 may also be particles containing a material with high thermal conductivity. By including a material with high thermal conductivity, the thermal conductivity of the heat shielding layer 17 can be increased. As a result, heat dissipation is improved and heat insulation can be imparted. In this case, the heat shielding layer 17 can also be considered as a heat dissipation layer. Examples of materials with high thermal conductivity include alumina, carbon nanotubes, diamond, silver, silicon, and particles of these materials.

Furthermore, the heat shielding particles 172 may be particles containing a material with low thermal conductivity. By containing a material with low thermal conductivity, the thermal conductivity of the heat shielding layer 17 can be reduced. As a result, the heat insulation properties are improved and heat blocking properties can be imparted. In this case, the heat shielding layer 17 can also be considered as an insulating layer. Examples of materials with low thermal conductivity include hollow particles made of silica and alumina resin.

The heat shielding layer 17 has a thickness of 300 nm or more and 1500 nm or less. If the thickness of the heat shielding layer 17 is less than 300 nm, the heat shielding properties are reduced. If the thickness of the heat shielding layer 17 is more than 1500 nm, the light transmittance is reduced, and the optical properties of the resin film are reduced.

The high refractive index layer 18 is provided between the heat shield layer 17 and the low refractive index layer 19, and is a functional layer for further reducing the reflectance. The high refractive index layer 18 has a higher refractive index than the low refractive index layer 19. More specifically, the high refractive index layer 18 is provided to adjust the optical properties to make the resin film have a low reflectance.
The high refractive index layer 18 includes a binder 181 and high refractive index particles 182. The high refractive index layer 18 may be formed as a single layer or as multiple layers, but is preferably formed with as few layers as possible from the viewpoint of manufacturing costs.

In order to reduce the reflectance of the liquid crystal panel 1a, it is preferable to increase the refractive index of the high refractive index layer 18. Specifically, the refractive index is preferably 1.55 or more and 1.85 or less, and more preferably 1.60 or more and 1.80 or less.
The upper limit of the thickness of the high refractive index layer 18 is preferably 500 nm or less, more preferably 350 nm or less, and even more preferably 200 nm or less. The lower limit of the thickness of the high refractive index layer 18 is preferably 50 nm or more, more preferably 80 nm or more, and even more preferably 100 nm or more.

Examples of the high refractive index particles 182 include zirconium oxide (zirconium oxide) and hafnium oxide (hafnium oxide). Other examples include tantalum oxide (tantalum oxide), titanium oxide (titanium oxide), and zinc oxide (zinc oxide). Other examples include aluminum oxide (aluminum oxide) and magnesium oxide (magnesium oxide). Other examples include tin oxide (tin oxide) and yttrium oxide (yttrium oxide). Other examples include barium titanate and antimony-containing tin oxide (ATO). Other examples include phosphorus-containing tin oxide (PTO), indium-containing tin oxide (ITO), and zinc sulfide. From the viewpoint of durability and stability, zirconium oxide (zirconium oxide), barium titanate, antimony-containing tin oxide (ATO), phosphorus-containing tin oxide (PTO), and indium-containing tin oxide (ITO) are particularly preferred.

The average particle diameter (average primary particle diameter) of the primary particles of the high refractive index particles 182 is preferably 1 nm or more and 200 nm or less, more preferably 3 nm or more and 100 nm or less, and even more preferably 5 nm or more and 50 nm or less.
The average primary particle diameter of the high refractive index particles 182 can be measured from images of a dried film of the particle dispersion liquid observed using a scanning electron microscope (SEM), a transmission electron microscope (TEM), and a scanning transmission electron microscope (STEM).

The high refractive index particles 182 are preferably subjected to a dispersion stabilization treatment in order to suppress aggregation. Examples of dispersion stabilization methods include using surface-treated particles and adding a dispersant. Another example is adding other particles with a smaller surface charge than the high refractive index particles 182.

The content of the high refractive index particles 182 is preferably 20 parts by weight or more and 600 parts by weight or less per 100 parts by weight of the binder. It is more preferable that the content is 50 parts by weight or more and 500 parts by weight or less, and even more preferable that the content is 100 parts by weight or more and 400 parts by weight or less.

The binder 181 is not particularly limited as long as it has excellent light transmission and, when used as a resin film, has the strength appropriate for the application. For example, the same as the example of the low refractive index layer 19 described later can be used. However, in order to reduce the content of the high refractive index particles 182, it is preferable that the refractive index of the binder 181 is approximately 1.48 or more and 1.70 or less.

The low refractive index layer 19 is a functional layer for reducing the reflectance of the liquid crystal panel 1a.
The low refractive index layer 19 has a smaller refractive index than the high refractive index layer 18. The low refractive index layer 19 also has a lower refractive index than the heat shielding layer 17. Specifically, the low refractive index layer 19 preferably has a refractive index of 1.20 or more and 1.35 or less. In this case, the SCI (specular component included) reflectance Y described later is 0.3 or less. This allows a liquid crystal panel 1a with low reflectance to be realized. The low refractive index layer 19 may be formed as a single layer or multiple layers, but is preferably formed with as few layers as possible from the viewpoint of manufacturing costs. The low refractive index layer 19 preferably has a thickness of 50 nm or more and 500 nm or less.

The low refractive index layer 19 includes a binder 191 and hollow silica particles 192 distributed in the binder 191. The low refractive index layer 19 further includes a surface modifier 193 that is distributed mainly on the surface side of the binder 191.

The binder 191 has a mesh structure and connects the hollow silica particles 192 together. The binder 191 contains a resin as a main component. The resin preferably contains a fluorine-containing resin. In this case, the resin may be entirely fluorine-containing resin, or may be partially fluorine-containing resin. The fluorine-containing resin is a resin containing fluorine, such as polytetrafluoroethylene (PTFE). Another example is perfluoroalkoxyalkane (PFA). Another example is perfluoroethylenepropene copolymer (FEP) or ethylenetetrafluoroethylene copolymer (ETFE). Fluorine-containing resins have a low refractive index. Therefore, by using a fluorine-containing resin, the low refractive index layer 19 is more likely to have a lower refractive index, and the reflectance can be further reduced.

Moreover, the fluorine-containing resin is more preferably a photocurable fluorine-containing resin. The photocurable fluorine-containing resin is a resin obtained by photopolymerizing a photopolymerizable fluorine-containing monomer represented by the following general formulas (1) and (2). The resin contains 0.1 mol % or more and 100 mol % or less of the structural unit M. The resin also contains more than 0 mol % and 99.9 mol % or less of the structural unit A. The number average molecular weight is 30,000 or more and 1,000,000 or less.

In the general formula (1), the structural unit M is a structural unit derived from a fluorine-containing ethylenic monomer represented by the general formula (2). The structural unit A is a structural unit derived from a monomer copolymerizable with the fluorine-containing ethylenic monomer represented by the general formula (2).
In the general formula (2), ^X1 and ^X2 are H or F. ^X3 is H, F, _CH3 or _CF3 . ^X4 and ^X5 are H, F or _CF3 . Rf is an organic group in which 1 to 3 Y1 are bonded to a fluorine-containing alkyl group having 1 to 40 carbon atoms or a fluorine-containing alkyl group having an ether bond having 2 to 100 carbon atoms. ^Y1 is ^a monovalent organic group having 2 to 10 carbon atoms and an ethylenic carbon-carbon double bond at the terminal. In addition, a is 0, 1, 2 or 3, and b and c are 0 or 1.
Examples of photopolymerizable fluorine-containing resins include OPTOOL AR-110 manufactured by Daikin Industries, Ltd. Other examples include EBECRYL8110 manufactured by Daicel Allnex Corporation and the LINC series manufactured by Kyoeisha Chemical Co., Ltd.
Specific examples of binders that do not contain fluorine atoms include light acrylate POB-A, NP-A, DCP-A, TMP-A, UA-306I, and UA-306H manufactured by Kyoeisha Chemical Co., Ltd. Further examples include NK ester A-DOD-N, A-200, and A-BPE-4 manufactured by Shin-Nakamura Chemical Co., Ltd. Further examples include Aronix M-315, M-306, and M-408 manufactured by Toagosei Co., Ltd. Further examples include KAYARAD DPHA and DPEA-12 manufactured by Nippon Kayaku Co., Ltd. These binders are effective in improving film strength such as steel wool resistance and pencil hardness, which will be described in detail later.

The hollow silica particles 192 have an outer shell layer, and the inside of the outer shell layer is hollow or porous. The outer shell layer and the porous body are mainly composed of silicon oxide (SiO ₂ ). A large number of photopolymerizable groups and hydroxyl groups are bonded to the surface side of the outer shell layer. The photopolymerizable groups and the outer shell layer are bonded via at least one of Si-O-Si bonds and hydrogen bonds. Examples of the photopolymerizable groups include acryloyl groups and methacryloyl groups. That is, the hollow silica particles 192 include at least one of acryloyl groups and methacryloyl groups as the photopolymerizable groups. The photopolymerizable groups are also called ionizing radiation curable groups. The hollow silica particles 192 only need to have at least a photopolymerizable group, and the number and types of these functional groups are not particularly limited.

The average primary particle diameter of the hollow silica particles 192 is preferably 35 nm or more and 120 nm or less. It is more preferable that the average primary particle diameter of the hollow silica particles 192 is 50 nm or more and 100 nm or less. If the average primary particle diameter is less than 35 nm, the porosity of the hollow silica particles 192 is likely to be small. Therefore, it is difficult to achieve the effect of lowering the refractive index of the low refractive index layer 19. Furthermore, if the median particle diameter exceeds 120 nm, the unevenness of the surface of the low refractive index layer 19 is likely to become noticeable. Therefore, the anti-fouling properties and scratch resistance are likely to decrease.

The average primary particle diameter of the hollow silica particles 192 can be measured in the same manner as for the high refractive index layer 18. That is, it can be measured from images of the dried film of the particle dispersion liquid observed using SEM, TEM, and STEM.

The amount of hollow silica particles 192 in the low refractive index layer 19 is preferably 30% by mass or more and 65% by mass or less. If the amount of hollow silica particles 192 is less than 30% by mass, the reflectance of the low refractive index layer 19 tends to be high. If the amount of hollow silica particles 192 is more than 65% by mass, the film strength tends to decrease. Furthermore, any attached matter becomes noticeable and difficult to wipe off.

The hollow silica particles 192 can also be made to have multiple maximum values in the frequency curve (particle size distribution curve) for the particle size of the hollow silica particles 192. In other words, in this case, the hollow silica particles 192 are made up of multiple particles with different particle size distributions. For example, multiple hollow silica particles 192 with average primary particle diameters of 30 nm, 60 nm, and 75 nm are selected and mixed for use.

The surface modifier 193 is distributed mainly on the surface side of the binder 191, and modifies the surface of the low refractive index layer 19. That is, the surface modifier 193 segregates on the surface side of the low refractive index layer 19. Note that even if the surface modifier 193 is present inside the binder 191, it does not impair the function of the low refractive index layer 19.
In this embodiment, the surface modifier 193 includes an oil-repellent surface modifier and an oleophilic surface modifier.

The oil-repellent surface modifier is mixed with binder 191 and segregates on the surface, thereby improving the oil repellency of the film surface. The effect of the oil-repellent surface modifier can be confirmed by measuring the contact angle of oleic acid, etc. In this case, the effect can be confirmed by the difference in contact angle of the film surface when the oil-repellent surface modifier is added and when it is not added (contact angle when added - contact angle when not added). In this case, the contact angle increases when the oil-repellent surface modifier is added. It is preferable that the difference in contact angle is 10° or more. It is more preferable that the difference in contact angle is 20° or more, and even more preferable that it is 30° or more.

The oil-repellent surface modifier is preferably a fluorine-based compound having a photopolymerizable group.
Specific examples of oil-repellent surface modifiers include KY-1203 and KY-1207 manufactured by Shin-Etsu Chemical Co., Ltd. Also, for example, Optool DAC-HP manufactured by Daikin Industries, Ltd. Furthermore, for example, Megafac F-477, F-554, F-556, F-570, RS-56, RS-58, RS-75, RS-78, and RS-90 manufactured by DIC Corporation are included. Furthermore, for example, FS-7024, FS-7025, FS-7026, FS-7031, and FS-7032 manufactured by Fluorotechnology Co., Ltd. are included. Furthermore, for example, H-3593 and H-3594 manufactured by Daiichi Kogyo Seiyaku Co., Ltd. are included. Furthermore, for example, SURECO AF Series manufactured by AGC Inc. are included. Examples of such adhesives include F-222F, M-250, 601AD, and 601ADH2 manufactured by Neos Corporation.

The lipophilic surface modifier is mixed with the binder 191 etc. and segregates on the surface, thereby improving the lipophilicity of the film surface. The effect of the lipophilic surface modifier can be confirmed by measuring the contact angle of oleic acid etc. In this case, the effect can be confirmed by the difference in the contact angle of the film surface when the lipophilic surface modifier is not added and when it is added (contact angle when not added - contact angle when added). In this case, the contact angle becomes smaller when the lipophilic surface modifier is added. And it is preferable that the difference in contact angle is 3° or more. Furthermore, it is more preferable that the difference in contact angle is 5° or more, and even more preferable that it is 7° or more.

Specific examples of lipophilic surface modifiers include Merclear 350L manufactured by Sanyo Chemical Industries, Ltd., and Futergent 730LM, 602A, 650A, and 650AC manufactured by Neos Corporation.

Even if sebum or other contaminants adhere to the low refractive index layer 19, the contaminants are not noticeable. In addition, the contaminants can be easily wiped off. This is true even if the layer contains a large amount of hollow silica particles 192.

<Description of the Relationship Between the Refractive Index of the Hard Coat Layer 16 and the Heat Shield Layer 17>
In this embodiment, the difference in refractive index between heat shield layer 17 and an adjacent layer that is adjacent to heat shield layer 17 and is a layer other than low refractive index layer 19 is important. In this case, the adjacent layer corresponds to hard coat layer 16 that is the layer below heat shield layer 17. In this case, it can also be said that low refractive index layer 19 is provided on the opposite side of heat shield layer 17 to hard coat layer 16, which is the adjacent layer.
The difference in refractive index between the hard coat layer 16 and the heat shield layer 17 must be 0.04 or less. In this case, as long as the difference in refractive index is 0.04 or less, it does not matter whether the refractive index of the hard coat layer 16 or the refractive index of the heat shield layer 17 is larger.
This matter will be explained below.

FIG. 3 is a diagram showing the reflectance when the difference in refractive index between the hard coat layer 16 and the heat shield layer 17 is changed.
Here, the horizontal axis represents the wavelength of light, and the vertical axis represents the reflectance. That is, Fig. 3 is a diagram showing the change in reflectance with respect to wavelength.
Here, the hard coat layer 16 and the heat shield layer 17 are formed on the substrate 15 made of a TAC film, and no other layers are formed. The refractive index of the heat shield layer 17 is fixed, and the refractive index of the hard coat layer 16 is changed.
Specifically, the change in reflectance versus wavelength was examined for Experimental Example A1, Comparative Experimental Example B1, and Comparative Experimental Example B2. As shown in Table 1, Experimental Example A1 is a case where the refractive index of the hard coat layer 16 is 0.01 higher than that of the heat shield layer 17. Comparative Experimental Example B1 is a case where the refractive index of the hard coat layer 16 is 0.05 higher than that of the heat shield layer 17. Comparative Experimental Example B2 is a case where the refractive index of the hard coat layer 16 is 0.05 lower than that of the heat shield layer 17.

Comparative Experimental Example B1 and Comparative Experimental Example B2 in Figure 3 are cases where the difference in refractive index between the hard coat layer 16 and the heat shielding layer 17 is large. In this case, optical interference occurs between these layers, causing the spectrum to fluctuate significantly. On the other hand, when the difference in refractive index between these layers becomes small, the optical interface between the layers disappears. As a result, the spectrum becomes less wavy, as shown in Experimental Example A1.

FIG. 4 is a diagram showing a case where a high refractive index layer 18 and a low refractive index layer 19 are further added to the case of FIG.
In this case, a resin film is formed by having a hard coat layer 16, a heat shielding layer 17, a high refractive index layer 18, and a low refractive index layer 19 on a substrate 15 made of a TAC film. Fig. 4 is a diagram showing the reflectance when the difference in refractive index between the hard coat layer 16 and the heat shielding layer 17 is changed. Here again, the horizontal axis represents the wavelength of light, and the vertical axis represents the reflectance.
Table 1 shows the SCI reflectance Y at this time.
Comparative Experimental Example B1 and Comparative Experimental Example B2 in Figure 4 have waves in the spectrum, and the film has color unevenness and large color change when observed from an oblique angle. In addition, the SCI reflectance Y is high, as shown in Table 1. On the other hand, Experimental Example A1 has a flat spectrum, so there is little color unevenness and color change, and the SCI reflectance Y is also low.

<Description of methods for producing the hard coat layer 16, the heat shield layer 17, the high refractive index layer 18, and the low refractive index layer 19>
Next, methods for forming the hard coat layer 16, the heat shield layer 17, the high refractive index layer 18, and the low refractive index layer 19 will be described.
FIG. 5A is a flow chart showing a method for producing a resin film having a layered structure as shown in FIG.
First, the hard coat layer 16 is formed on the substrate 15. The hard coat layer 16 is adjacent to the heat shield layer 17, is a layer other than the low refractive index layer 19, and serves as an adjacent layer having a refractive index difference of 0.04 or less with respect to the heat shield layer 17 (Step 101: adjacent layer forming step).
Next, a heat shield layer 17 having a thickness of 300 nm or more and 1500 nm or less for blocking heat is formed on the hard coat layer 16 (step 102: heat shield layer forming step).
Furthermore, a high refractive index layer 18 having a refractive index higher than that of the low refractive index layer 19 is formed on the heat shield layer 17 (step 103: high refractive index layer forming step).
Then, a low refractive index layer having a refractive index lower than that of the heat shield layer 17 and the high refractive index layer 18 is formed on the high refractive index layer 18 (step 104: low refractive index layer forming step).

The hard coat layer 16, the heat shield layer 17, the high refractive index layer 18 and the low refractive index layer 19 can each be formed by the following method.
FIG. 5( b ) is a flow chart illustrating a method for forming the hard coat layer 16 , the heat shield layer 17 , the high refractive index layer 18 , and the low refractive index layer 19 .
First, a coating solution for forming each layer is prepared (step 201: preparation step). Here, "preparation" includes not only a case where the coating solution is prepared by creating it, but also a case where the coating solution is purchased and prepared.

The coating solution is composed of a solid component and a solvent.
When the hard coat layer 16 is formed, the solid content contains monomers and oligomers that are the base of the binder 161. The solid content also contains metal oxide particles 162. The monomers and/or oligomers are polymerized to become the resin contained in the binder 161. In this embodiment, the polymerization is photopolymerization. Hereinafter, the monomers and/or oligomers may be referred to as "binder components".
When the thermal barrier layer 17 is formed, the solid content includes a binder component that is the basis of the binder 171. The solid content also includes the thermal barrier particles 172.
When the high refractive index layer 18 is formed, the solid content includes a binder component that is the basis of the binder 181. The solid content also includes high refractive index particles 182.
When forming the low refractive index layer 19, the solid content includes a binder component that is the basis of the binder 191. The solid content also includes hollow silica particles 192 and a surface modifier 193.
The solid content of each layer includes a photopolymerization initiator, and may further include a dispersant, a defoamer, an ultraviolet absorbing agent, a leveling agent, etc.
Then, each solid content is added to a solvent and stirred to prepare a coating solution for each layer.

The solvent disperses the solids. Examples of the solvent that can be used include methylene chloride, toluene, xylene, ethyl acetate, butyl acetate, and acetone. Also, MEK (methyl ethyl ketone), MIBK (methyl isobutyl ketone), ethanol, methanol, and normal propyl alcohol can be used. Furthermore, isopropyl alcohol, tert-butyl alcohol, 1-butanol, mineral spirits, oleic acid, and cyclohexanone can be used. Furthermore, NMP (N-methylpyrrolidone), DMP (dimethyl phthalate), dimethyl carbonate, and dioxolane can be used.

Returning to Fig. 5B, next, a coating solution is applied to create a coating film (step 202: coating step). The method of coating is not particularly limited, but it can be performed by dropping the coating solution and applying it with a bar coater. It is also possible to adopt a method of dropping the coating solution, rotating it, and creating a film-like body of uniform thickness by centrifugal force.
At this time, the surface modifier of the low refractive index layer 19 segregates on the surface side of the coating film.

The applied coating film is then dried (step 203: drying step). Drying can be performed by leaving it at room temperature to evaporate the solvent, or by forcibly removing the solvent by heating or vacuuming, etc.

Then, light such as ultraviolet light is applied to photopolymerize the binder component in the coating film. This hardens the binder component in the coating film to become binders 161, 171, 181, and 191 (step 204: polymerization process). Through the above processes, the hard coat layer 16, the heat shielding layer 17, the high refractive index layer 18, and the low refractive index layer 19 can be formed. The drying process and polymerization process can be considered as curing processes that harden the applied coating solution.

In the above example, the display device 1 has the hard coat layer 16, the heat shield layer 17, the high refractive index layer 18, and the low refractive index layer 19 formed on the liquid crystal panel. However, the present invention is not limited to this, and the layers may be formed on an organic EL display or a cathode ray tube, for example.
These layers may also be formed on the surface of a lens or the like made of a material such as glass or plastic. In this case, the lens or the like is an example of a substrate. A lens or the like on which the hard coat layer 16, the high refractive index layer 18, and the low refractive index layer 19 are formed is an example of an optical member. A film made of TAC or the like can be used as the substrate. These layers may then be formed on this film. This can be used as a low refractive index film or an anti-reflection film. This is also an example of an optical member.
In addition, the polarizing film 12 may be formed with a hard coat layer 16, a heat shielding layer 17, a high refractive index layer 18, and a low refractive index layer 19. This is an example of a polarizing member, and can be used as a polarizing film.

In the above-mentioned example, the hard coat layer 16 and the high refractive index layer 18 are provided, but if these are not required, they do not need to be provided. In other words, there are cases where it is not necessary to provide either the hard coat layer 16 or the high refractive index layer 18. Also, there are cases where it is not necessary to provide both the hard coat layer 16 and the high refractive index layer 18. In addition, if there is no hard coat layer 16, the adjacent layer becomes the substrate 15 or a substrate such as a lens.
Furthermore, in the above example, the binder component is polymerized by photopolymerization, but the binder component may be polymerized by thermal polymerization.

<Modification>
In the above-mentioned example, the hard coat layer 16 and the heat shield layer 17 are formed separately. However, they can be formed at the same time.

FIG. 6 is a diagram showing a structure in which the hard coat layer 16 and the heat shield layer 17 are formed at the same time.
As shown in the figure, in this case, a heat shielding adjacent layer 20, a high refractive index layer 18 and a low refractive index layer 19 are laminated.
The heat shielding adjacent layer 20 includes a binder 201 as a base material whose main component is resin.
The heat shielding adjacent layer 20 also includes heat shielding particles 202 having heat shielding properties. The heat shielding particles 202 include, for example, at least one of an infrared absorbing material and an infrared reflective material. The heat shielding adjacent layer 20 includes this material such that the concentration on the surface side in the thickness direction is greater than the concentration on the opposite side to the surface side. That is, in the heat shielding adjacent layer 20, the heat shielding particles 202 are unevenly distributed on the surface side. The heat shielding particles 202 can be the same as the heat shielding particles 172. Furthermore, a material with high thermal conductivity or a material with low thermal conductivity as described above in the description of the heat shielding layer 17 may be used as the heat shielding particles 202.

The heat shielding adjacent layer 20 has both the functions of the hard coat layer 16 and the heat shielding layer 17. In other words, the surface side of the heat shielding adjacent layer 20 has the function of the heat shielding layer 17 because the heat shielding particles 202 are unevenly distributed thereon. In contrast, the inner side of the heat shielding adjacent layer 20 has the function of the hard coat layer 16. This means that the upper layer of the heat shielding adjacent layer 20 has the function of the heat shielding layer 17, and the lower layer of the heat shielding adjacent layer 20 has the function of the hard coat layer 16. However, there is no boundary between them. The function of the heat shielding layer 17 and the function of the hard coat layer 16 change continuously in the thickness direction. There is also no optical interface, and the optical properties also change continuously in the thickness direction.

FIG. 7 is a flow chart showing a method for producing a resin film having the structure shown in FIG.
First, the above-mentioned heat shielding adjacent layer 20 is formed on the substrate 15 (step 301: heat shielding adjacent layer forming step).
The thermal barrier adjacent layer 20 can be produced by the same method as that shown in Fig. 5(b) . That is, the thermal barrier adjacent layer 20 can be produced by sequentially carrying out the steps of a preparation step, a coating step, a drying step, and a polymerization step.

8(a) to (c) are diagrams showing a method for producing the heat shielding adjacent layer 20. FIG.
In this case, as shown in Fig. 8(a) , a coating solution T is prepared (preparation step) and dropped onto the substrate 15. In the coating solution T, heat shielding particles 202 are dispersed in a solvent L. Note that solid contents other than the heat shielding particles 202 are also dispersed in the solvent L. When the coating solution T is applied with a bar coater or the like, a coating film made of the coating solution T is formed as shown in Fig. 8(b) (coating step).
After coating, the heat shielding particles 202 segregate to the surface side of the coating film. After further undergoing a drying process and a polymerization process, the heat shielding adjacent layer 20 in which the heat shielding particles 202 segregate to the surface side is formed, as shown in Fig. 8(c) . As a method for segregating the heat shielding particles 202 to the surface side, for example, a surface treatment is performed on the heat shielding particles 202. This can be used to control the surface energy of the heat shielding particles 202 and the compatibility with the binder 201.

Returning to FIG. 7, the process of creating the high refractive index layer in step 302 is the same as step 103 in FIG. 5(a). Also, the process of creating the low refractive index layer in step 303 is the same as step 104 in FIG. 5(a).

By forming the heat-shielding adjacent layer 20 as described above, it is possible to provide a resin film or the like that can achieve both optical properties and heat insulation properties. In other words, the optical properties can be achieved by making the difference in refractive index between the heat-shielding layer 17 and the adjacent layer, such as the hard coat layer 16, 0.04 or less. In addition, the heat-shielding layer 17 can be made to have a thickness of 300 nm or more and 1500 nm or less. In this case, it is preferable that the low refractive index layer 19 is provided on the opposite side of the hard coat layer 16 with the heat-shielding layer 17 in between. In other words, when the high refractive index layer 18 is provided, it is preferable to provide the hard coat layer 16, the heat-shielding layer 17, the high refractive index layer 18, and the low refractive index layer 19 in this order from the inside to the surface side.

The present invention will be described in more detail below using examples. The present invention is not limited to these examples as long as the gist of the invention is not exceeded.

[Formation of hard coat layer 16]
First, a description will be given of a method for producing the hard coat layer 16. Here, coating solutions HC-1 to HC-8 for the hard coat layer 16 were prepared with the compositions shown in Table 2.

(Coating solution HC-1)
The coating solution HC-1 contains a monomer and/or oligomer as a binder component, and metal oxide particles 162. The coating solution HC-1 also contains a photopolymerization initiator, an antifoaming agent, and a solvent. The binder component used was UA-306T manufactured by Kyoeisha Chemical Co., Ltd. The binder components further used were Viscoat #300 manufactured by Osaka Organic Chemical Industry Co., Ltd. and KAYARAD PET-30 manufactured by Nippon Kayaku Co., Ltd. The metal oxide particles 162 used zirconium oxide, which is a nanoparticle having an average primary particle size of 30 nm. The photopolymerization initiator used was IRGACURE184 manufactured by BASF Japan Co., Ltd. The antifoaming agent used was BYK-066N manufactured by ALTANA Co., Ltd. These are solid contents, and the compounding ratio is as shown in Table 2.
These solid contents were then added to a solvent so as to give a solid content of 50 mass %, and stirred. The solvents used were methyl ethyl ketone, methyl isobutyl ketone, and dimethyl carbonate. The compounding ratios of these were as shown in Table 2. In this way, coating solution HC-1 was prepared.

(Coating solution HC-2, HC-3)
In the coating solutions HC-2 and HC-3, the compounding ratio of the binder component and the metal oxide particles 162 was changed from that of the coating solution HC-1.

(Coating solution HC-4, HC-5)
Coating solution HC-4 used antimony-containing tin oxide (ATO), which is nanoparticles having an average primary particle size of 20 nm, as the metal oxide particles 162. Coating solution HC-5 used phosphorus-containing tin oxide (PTO), which is nanoparticles having an average primary particle size of 20 nm, as the metal oxide particles 162.

(Coating solution HC-6)
The coating solution HC-6 did not contain the metal oxide particles 162. In addition, NR-121X-9IPA manufactured by Colcoat Co., Ltd. was used as the antistatic agent.

(Coating solution HC-7, HC-8)
In the coating solutions HC-7 and HC-8, the compounding ratio of the binder component and the metal oxide particles 162 was changed from that of the coating solution HC-1.

The coating solution was applied onto the substrate 15 with a wire bar to form a coating film. A TAC film was used as the substrate 15. The coating film was left at room temperature for 1 minute, and then dried by heating at 80°C for 1 minute. Then, the coating film was irradiated with an ultraviolet lamp (metal halide lamp, illuminance 300 mW/ ^cm2 ) for 1 second. This allows the coating film to be cured. The above steps allowed the hard coat layer 16 to be formed.

[Formation of heat shield layer 17]
Next, a method for producing the thermal barrier layer 17 will be described. Here, a coating solution for the thermal barrier layer 17 was prepared with the composition shown in Table 3.

(Coating solution HS-1)
The coating solution HS-1 contains a monomer and/or oligomer as a binder component, heat shielding particles 172, a photopolymerization initiator, and a solvent. KAYARAD DPHA manufactured by Nippon Kayaku Co., Ltd. was used as the binder component. Indium-containing tin oxide (ITO), which is a nanoparticle having an average primary particle diameter of 30 nm, was used as the heat shielding particles 172. Furthermore, IRGACURE184 manufactured by BASF Japan Ltd. was used as the photopolymerization initiator. These are solid contents, and the compounding ratio is as shown in Table 3.
These solid contents were then added to a solvent, methyl isobutyl ketone, so as to have a solid content of 25% by mass, and stirred to prepare a coating solution HS-1.

(Coating solution HS-2, HS-3)
Coating solutions HS-2 and HS-3 were prepared by changing the blending ratio of the binder component and the heat shielding particles 172 from that of coating solution HS-1. Coating solution HS-2 further contained Megafac F-568 manufactured by DIC Corporation as a fluorine-based additive.

(Coating solution HS-4)
The coating solution HS-4 further used AR-100 manufactured by Daikin Industries, Ltd. as a binder component. Indium-containing tin oxide (ITO) that was subjected to a hydrophobic surface treatment was used as the heat shielding particles 172. These are nanoparticles with an average primary particle diameter of 50 nm.

(Coating solution HS-5, HS-6)
The coating solution HS-5 used antimony-containing tin oxide (ATO), which is a nanoparticle having an average primary particle diameter of 20 nm, as the heat shielding particles 172. The coating solution HS-6 used phosphorus-containing tin oxide (PTO), which is a nanoparticle having an average primary particle diameter of 20 nm, as the heat shielding particles 172.

The coating solution was applied onto the hard coat layer 16 with a wire bar to form a coating film. The coating film was then left to stand at room temperature for 1 minute, and then dried by heating at 80°C for 2 minutes. Then, the coating film was irradiated with an ultraviolet lamp (metal halide lamp, illuminance 300 mW/ ^cm2 ) for 1 second. This allows the coating film to harden. The above steps allowed the heat shield layer 17 to be formed.

[Formation of high refractive index layer 18]
Next, a description will be given of a method for producing the high refractive index layer 18. Here, a coating solution for the high refractive index layer 18 was prepared with the composition shown in Table 4.

(Coating solution HR-1)
The coating solution HR-1 contains a monomer and/or oligomer as a binder component, high refractive index particles 182, a photopolymerization initiator, and a solvent. KAYARAD DPHA manufactured by Nippon Kayaku Co., Ltd. was used as the binder component. Furthermore, zirconium oxide, which is nanoparticles having an average primary particle diameter of 10 nm, was used as the high refractive index particles 182. Furthermore, IRGACURE184 manufactured by BASF Japan Ltd. was used as the photopolymerization initiator. These are solid contents, and the compounding ratio is as shown in Table 4.
These solid contents were then added to a solvent, methyl isobutyl ketone, so as to have a solid content of 10% by mass, and stirred to prepare a coating solution for the high refractive index layer 18.

(Coating solutions HR-2 and HR-3)
In the coating solutions HR-2 and HR-3, the compounding ratio of the binder component and the high refractive index particles 182 was changed from that of the coating solution HR-1.

The coating solution was applied onto the heat shield layer 17 with a wire bar to form a coating film. The coating film was then left at room temperature for 1 minute, and then dried by heating at 80°C for 2 minutes. Then, the coating film was irradiated with an ultraviolet lamp (metal halide lamp, illuminance 300 mW/ ^cm2 ) for 1 second. This allows the coating film to harden. Through the above steps, the high refractive index layer 18 was formed.

[Formation of low refractive index layer 19]
Next, a description will be given of a method for producing the low refractive index layer 19. Here, a coating solution for the low refractive index layer 19 having the composition shown in Table 5 was prepared.

(Coating solution LR-1)
The coating solution LR-1 contains a binder component, a monomer and/or an oligomer, and hollow silica particles 192. The coating solution LR-1 also contains a photopolymerization initiator, an oil-repellent surface modifier 193, and an oleophilic surface modifier 193. The coating solution further contains a defoamer and a solvent. As the binder component, OPTOOL AR-100 manufactured by Daikin Industries, Ltd. was used. As the binder component, KAYARAD PET-30 manufactured by Nippon Kayaku Co., Ltd. was used. As the hollow silica particles 192, particles having an average primary particle diameter of 60 nm and 10 nm were used. As the photopolymerization initiator, IRGACURE127 manufactured by BASF Japan Ltd. was used. As the oleophobic surface modifier 193, KY-1203 manufactured by Shin-Etsu Chemical Co., Ltd. was used. As the oleophilic surface modifier 193, Futergent 650A manufactured by Neos Co., Ltd. was used. As the defoaming agent, BYK-066N manufactured by ALTANA was used. These are solid contents, and the mass blending ratios are as shown in Table 5.
These solid contents were then added to a mixed solution of methyl isobutyl ketone and tert-butyl alcohol as a solvent, and stirred. At this time, the solid contents were adjusted to 5 mass %. In this way, a coating solution for the low refractive index layer 19 was prepared. The mass blending ratio of the solvents was as shown in Table 5.

(Coating solution LR-2)
In the coating solution LR-2, hollow silica particles 192 having average primary particle diameters of 75 nm and 10 nm were used. Also, the compounding ratio of the binder component and the hollow silica particles 192 was changed from that of the coating solution LR-1.

The coating solution was applied onto the high refractive index layer 18 with a wire bar to form a coating film. The coating film was then left at room temperature for 1 minute, and then dried by heating at 80°C for 3 minutes. Then, the coating film was irradiated with an ultraviolet lamp (metal halide lamp, illuminance 300 mW/ ^cm2 ) for 1 second in a nitrogen gas-purged atmosphere. This allows the coating film to harden. The above steps allowed the low refractive index layer 19 to be formed.

[Configuration of resin film]
Next, a description will be given of the combination of the above-mentioned hard coat layer 16, heat shield layer 17, high refractive index layer 18, and low refractive index layer 19. Here, each of these layers was formed using the combination of coating solutions shown in Table 6.

Example 1
In Example 1, a hard coat layer 16 was formed using coating solution HC-1. A heat shield layer 17 was formed on the hard coat layer 16 using coating solution HS-1. A high refractive index layer 18 was formed on the heat shield layer 17 using coating solution HR-1. A low refractive index layer 19 was formed on the high refractive index layer 18 using coating solution LR-1.

(Examples 2 to 14)
In Examples 2 to 14, each layer was formed using the combination of coating solutions shown in Tables 6 to 7.
Among these, Example 2 is a case where the high refractive index layer 18 is not formed.
Examples 3 and 4 are cases where the content of the thermal barrier particles 172 contained in the thermal barrier layer 17 was changed. Example 3 is a case where the indium-containing tin oxide particles were 45 mass% with respect to the total mass of the thermal barrier layer 17. Example 4 is a case where the indium-containing tin oxide particles were 95.5 mass% with respect to the total mass of the thermal barrier layer 17.
In Example 5, as in the above-mentioned modified example, the hard coat layer 16 and the thermal barrier layer 17 were formed at the same time to form the thermal barrier adjacent layer 20 .
In Examples 6 to 10, the thickness of the heat shield layer 17 was changed from 300 nm to 1480 nm.
In Example 11, the thermal barrier particles 172 of the thermal barrier layer 17 are made of antimony-containing tin oxide (ATO). In Example 12, the thermal barrier particles 172 are made of phosphorus-containing tin oxide (PTO).
Example 13 is a case where the difference in refractive index between the heat shield layer 17 and the adjacent hard coat layer 16 is 0.04. Example 14 is a case where the difference in refractive index between the heat shield layer 17 and the adjacent hard coat layer 16 is 0.03.

(Comparative Examples 1 to 6)
As Comparative Examples 1 to 6, the layers were prepared using the combinations of coating solutions shown in Table 8.
Of these, Comparative Example 1 is a case where the thickness of the heat shield layer 17 is 250 nm, which is thinner than the lower limit of 300 nm, and Comparative Example 2 is a case where the thickness of the heat shield layer 17 is 1800 nm, which is thicker than the upper limit of 1500 nm.
In Comparative Example 3, the difference in refractive index between the heat shield layer 17 and the adjacent hard coat layer 16 was set to 0.11, which is greater than 0.04. In Comparative Example 4, the difference in refractive index between the heat shield layer 17 and the adjacent hard coat layer 16 was set to 0.06, which is greater than 0.04.
Comparative Examples 5 and 6 are cases in which the thermal barrier layer 17 was not formed.

[Evaluation method]
(film thickness, refractive index)
The film thickness of each layer was measured for Examples 1 to 14 and Comparative Examples 1 to 6. In addition, the refractive index of heat shield layer 17 and the refractive index of hard coat layer 16 were measured for Examples 1 to 14 and Comparative Examples 1 to 6. In addition, the difference in the refractive index between the two was calculated from the difference between these values.
The film thickness and refractive index were measured using a spectroscopic ellipsometer (VUV-VASE) manufactured by JA Woollam Co., Ltd. At this time, measurements were performed at n=3 points within the same sample, and the average value was adopted.

(SCI reflectance Y)
For Examples 1 to 14 and Comparative Examples 1 to 6, the SCI reflectance Y was measured.
The SCI reflectance Y was measured using a CM-2600d manufactured by Konica Minolta. The measurement was performed after attaching a black PET film to the back side of the measurement film. The smaller the SCI reflectance Y, the better the result. If the SCI reflectance Y was 0.4 or less, it was judged as passing. If it was less than 0.3, it was even better.

(transmittance)
The transmittance was measured for Examples 1 to 14 and Comparative Examples 1 to 6.
The transmittance was measured using a haze meter NDH5000W manufactured by Nippon Denshoku Industries Co., Ltd.
A higher transmittance indicates better optical properties. A transmittance of 90% or more was determined to be acceptable.

(Heat insulation performance)
The heat insulating properties of Examples 1 to 14 and Comparative Examples 1 to 6 were measured.
The heat-shielding performance was measured by attaching a resin film with double-sided tape to a hot plate heated to 60°C. The temperature difference (hot plate temperature - resin film temperature measured with a thermo camera) observed from above the resin film was confirmed. If this temperature difference was 0°C, it meant that there was no heat-shielding performance. The larger this temperature difference, the better the heat-shielding performance.

For Example 1, steel wool resistance and pencil hardness were evaluated to evaluate scratch resistance. Furthermore, for Example 1, the ease of wiping off dirt was evaluated.

(Steel wool resistant)
The steel wool resistance test is performed by rubbing the surface of the resin film with steel wool while applying a predetermined load. The steel wool used was Bonstar, product number: #0000, manufactured by Japan Steel Wool Co., Ltd. The moving speed was 100 mm/sec. The number of reciprocating movements was 10. Then, under fluorescent lighting, the resin film was observed visually while changing the angle, and the maximum load at which no scratches were generated was determined.
Regarding the steel wool resistance, the larger the maximum load, the harder the resin film is.

(Pencil hardness)
FIG. 9 is a diagram showing a pencil hardness measuring device for measuring pencil hardness.
The illustrated pencil hardness measuring device 200 includes wheels 210, a pencil 220, and a pencil clamp 230. The pencil hardness measuring device 200 further includes a level 240 and a housing 250.

Two wheels 210 are provided on both sides of the housing 250. The two wheels 210 are connected by an axle 211. The axle 211 is attached to the housing 250 via a bearing or the like (not shown). The wheels 210 are made of metal and have a rubber O-ring 212 on the outer diameter portion.

The pencil 220 is attached to the housing 250 via the pencil fastener 230. The pencil 220 has a lead 225 with a predetermined hardness at its tip. The pencil 220 is attached so that it is at a 45° angle to the resin film being tested. The tip of the lead 225 comes into contact with the resin film. The lead 225 is adjusted so that 5 to 6 mm is exposed by scraping the wooden part 226 of the pencil 220. The tip of the lead 225 is further polished with abrasive paper so that it is flat. A weight of 500 g is applied to the resin film at the tip of the lead 225.

In this configuration, the pencil hardness measuring device 200 can be moved by pushing the housing 250. In other words, when the pencil hardness measuring device 200 is pushed, it can be moved in the left-right direction in the figure on the resin film. At this time, the wheel 210 rotates, and the lead 225 of the pencil 220 moves while being pressed against the resin film.

When actually measuring the pencil hardness, first check that the pencil is level using the level 240. Then, move the lead 225 of the pencil 220 to the right in the figure while pressing it against the resin film. At this time, press it a distance of at least 7 mm at a speed of 0.8 mm/s. Then, visually check whether there are scratches on the resin film. This is done by replacing the pencil 220 and successively changing the hardness of the lead 225 from 6B to 6H. The hardness of the hardest lead 225 that did not cause scratches is taken as the pencil hardness.
The harder the pencil hardness, the harder the resin film.

(Wipeability)
A fingerprint was applied to the surface of the resin film as a stain and wiped off with tissue paper. The number of times the fingerprint could be wiped off was used to evaluate the wiping ability.
The smaller the number of times, the better the wiping ability.

[Evaluation results]
The evaluation results are shown in Tables 6 to 8.
In Examples 1 to 14, the SCI reflectance Y was 0.4 or less, which was acceptable. In addition, the transmittance was 90% or more, which was good. The heat shielding performance was 6°C or more in all cases, which confirmed that the films had heat shielding performance.
In Comparative Example 1, the SCI reflectance Y was 0.4 or less and passed the test, but the heat shielding performance was 3° C., which was inferior to the results of the Examples. This is believed to be a result of the film thickness of the heat shielding layer 17 being set at 250 nm, which is thinner than the lower limit of 300 nm.
In Comparative Example 2, the SCI reflectance Y was 0.4 or less, which was acceptable, but the transmittance was 89%, which was inferior to the Examples. This is considered to be a result of the thickness of the heat shield layer 17 being set to 1800 nm, which is thicker than the upper limit of 1500 nm.
In Comparative Examples 3 and 4, the heat shielding performance was good, but the SCI reflectance Y exceeded 0.4, and the samples were unsuccessful. This is believed to be because the difference in refractive index between the heat shielding layer 17 and the hard coat layer 16 exceeded 0.04.
In Comparative Examples 5 and 6, the SCI reflectance Y was 0.4 or less and passed the test, but the heat shielding performance was 0° C., resulting in no heat shielding performance. This is believed to be the result of not providing the heat shielding layer 17.

From the above results, as described above, the film thickness of the heat shield layer 17 must be 300 nm or more and 1500 nm or less. In addition, as described above, the difference in refractive index between the heat shield layer 17 and the hard coat layer 16 must be 0.04 or less.

In addition, in Example 1, the steel wool resistance was 1500 g/ ^cm2 or more. The pencil hardness was 3H. That is, the scratch resistance was good. Furthermore, the wiping ability was good, with the number of wiping attempts being 10 or less. That is, the wiping ability of the stains was good.

1...display device, 1a...liquid crystal panel, 11...backlight, 12, 12a, 12b...polarizing film, 13, 13a, 13b...phase difference film, 14...liquid crystal, 15...substrate, 16...hard coat layer, 17...heat shielding layer, 18...high refractive index layer, 19...low refractive index layer, 20...heat shielding adjacent layer, 161, 171, 181, 191...binder, 172...heat shielding particles

Claims (16)

A heat shielding layer having a thickness of 300 nm or more and 1500 nm or less for shielding heat;
a low refractive index layer having a refractive index lower than that of the heat shielding layer;
an adjacent layer that is adjacent to the heat shield layer, is a layer other than the low refractive index layer, and has a refractive index difference from the heat shield layer of 0.03 or less;
A resin film having the above structure. The resin film according to claim 1, characterized in that the low refractive index layer is provided on the opposite side of the heat shielding layer from the adjacent layer. The resin film according to claim 1 or 2, characterized in that the adjacent layer is a hard coat layer. The resin film according to claim 3, characterized in that the hard coat layer contains particles that increase the refractive index of the hard coat layer. The resin film according to claim 4, characterized in that the particles are at least one of zirconium oxide, aluminum oxide, titanium oxide, and tin oxide. The resin film according to claim 3, further comprising a high refractive index layer between the heat shielding layer and the low refractive index layer, the high refractive index layer having a higher refractive index than the low refractive index layer. The resin film according to claim 6, characterized in that the hard coat layer, the heat shielding layer, the high refractive index layer and the low refractive index layer are laminated in this order toward the surface side. The resin film according to claim 1 or 2, characterized in that the heat shielding layer contains at least one of an infrared absorbing material that absorbs infrared rays and an infrared reflecting material that reflects infrared rays. The resin film according to claim 8, characterized in that the infrared reflective material is at least one of indium-containing tin oxide particles, antimony-containing tin oxide particles, and phosphorus-containing tin oxide particles. The resin film according to claim 9, characterized in that the heat shield layer contains at least one of the indium-containing tin oxide particles, the antimony-containing tin oxide particles, and the phosphorus-containing tin oxide particles in an amount of 50% by mass or more and 95% by mass or less relative to the total mass of the heat shield layer. a heat shield layer forming step of forming a heat shield layer having a thickness of 300 nm or more and 1500 nm or less for blocking heat;
a low refractive index layer forming step of forming a low refractive index layer having a refractive index lower than that of the heat shielding layer;
an adjacent layer forming step of forming an adjacent layer adjacent to the heat shielding layer, the adjacent layer being a layer other than the low refractive index layer and having a refractive index difference from the heat shielding layer of 0.03 or less;
A method for producing a resin film comprising the steps of: 12. The method for producing a resin film according to claim 11 , wherein the low refractive index layer is provided on the opposite side of the heat shield layer from the adjacent layer. 13. The method for producing a resin film according to claim 11 , wherein the adjacent layer is a hard coat layer. A display means for displaying an image;
The resin film according to any one of claims 1 to 10 , which is provided on a surface of the display means;
A display device comprising: A substrate;
The resin film according to claim 1 , which is provided on the substrate;
An optical member having the above structure. A polarizing means for polarizing light;
The resin film according to claim 1 , which is provided on the polarizing means;
A polarizing member having the following structure: