JP2020095193A - Head-up display gate cover - Google Patents

Abstract

To provide a head-up display gate cover which features low retardation and higher durability and transparency, and offers improvement in terms of heat resistance of a liquid crystal display device, visibility of a displayed image, and durability of an entire head-up display system.SOLUTION: A head-up display gate cover 3 of the present invention comprises an infrared absorption layer and an infrared reflection layer provided on a resin substrate that exhibits an in-plane retardation value of 0 nm or greater and less than 100 nm when 550-nm light is incident at an incident angle of 0°, the infrared absorption layer containing an infrared absorber-1 and infrared absorber-2 having specific structures. The head-up display gate cover has an average transmittance of 80% or greater in a visible light wavelength range of 380-740 nm, and an average reflectance of 15% or greater in a near-infrared wavelength range of 750-1500 nm.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to a novel gate cover for a head-up display, and more specifically, it has a low phase difference value, high durability and high transparency of the gate cover, and heat resistance of a liquid crystal display device incorporated in the head-up display. And a gate cover for a head-up display capable of improving the visibility of a displayed image and the durability of the entire head-up display system.

In recent years, a head-up display (hereinafter, also simply referred to as “HUD”) installed on an instrument panel of a vehicle is becoming popular. The HUD transmits an image emitted from a liquid crystal display device (hereinafter, also referred to as “LCD” (Liquid Crystal Display)) or the like to a windshield through a gate cover for a head-up display (hereinafter, also simply referred to as “gate cover”). A device that projects various types of information to display various information within the driver's field of view, such as a type that displays it on a dedicated display or a type that displays driving information on the front window has been developed. Since HUD improves the safety of vehicles, it has been applied to some luxury vehicles until now, but the number of vehicles equipped with it is gradually increasing.

Currently, various forms of HUD are being developed based on various mechanisms. For example, the display unit does not display the windshield surface, but displays the traveling information and the like transmitted from the control unit by reflecting it on the windshield from the display unit of the instrument panel, so that the driver does not lower his line of sight and There is a form in which it is visually recognized within a normal visual field (that is, within the same visual field as the windshield). In such a configuration, image light is emitted from the image display device such as an LCD to the windshield, while sunlight from the windshield is condensed on the image display device, so that an image such as an LCD element is displayed. There is a problem that the constituent material of the display device becomes high in temperature and easily deteriorates due to overheating. Therefore, in the HUD, it is required to provide a heat shield means to the image display device.

In particular, in recent years, studies have been made to increase the size of the projected display image portion in order to increase the display information amount of the HUD and to further improve the safety of the vehicle by making the display image clear. However, as the size of the projected image becomes larger, the area of the gate cover of the HUD unit also becomes larger, so more sunlight is incident than in the conventional case, and the deterioration of the TFT-LCD, which is a liquid crystal display device, due to heat is suppressed. , High heat shield performance has been demanded for gate covers.

By the way, the wavelength distribution of the energy of the sunlight which is a heat shield target is divided into a visible light wavelength region (380 to 740 nm) and an infrared region (750 to 2500 nm). Visible light energy is shielded by a polarizing plate, and a cold mirror (reflects ultraviolet light and transmits infrared light) and a hot mirror (reflects infrared light) are used in the infrared region to suppress heat generation of the TFT-LCD. ing. However, it is said that it is difficult to increase the size of the projected image because the cold mirror is expensive and it is difficult to add curvature. Further, when a cold mirror is used, it is said that the infrared light enters the unit even if it is not focused on the TFT-LCD, so that the temperature inside the unit rises and, as a result, the TFT-LCD deteriorates.

With respect to the above problem, a head-up display including an optical laminated body formed by laminating an infrared absorbing layer having infrared absorbing performance and a polarizing film is disclosed (for example, refer to Patent Document 1). According to the method described in Patent Document 1, the disclosed optical layered body can shield the polarization component of natural light such as sunlight with a polarizing film, and can shield infrared light with an infrared absorption layer having infrared absorption performance. Therefore, it is said that it exerts an excellent shielding property in a wide wavelength range from visible light to infrared region.
However, the method proposed in Patent Document 1 has the following problems.

The first problem is that since the gate cover absorbs infrared rays, heat is generated in the gate cover, causing peeling of the adhesive layer or the like and deterioration of performance of the polarizing plate. The second problem is that the light transmittance in the visible light wavelength region is reduced in proportion to the amount of the infrared absorbing agent that constitutes the infrared absorbing layer. The third problem is that in the second problem, when the amount of the infrared absorber added is reduced to secure the visible light transmittance, the transmittance in the region of 750 to 1500 nm cannot be suppressed, Compared to cold mirrors, it lacks the ability to cut infrared rays.

On the other hand, unlike the infrared absorbing layer, the infrared reflecting layer does not trap heat in the gate cover, so that heat generation of the entire gate cover is suppressed, and the peeling of the adhesive layer and the functional deterioration of the polarizing plate as described above can be suppressed.

For example, a head-up display is disclosed, which has a reflection band of 200 nm or more in which the reflectance is continuously 70% or more in a region of a wavelength of 700 to 1400 nm of an infrared reflective film (for example, a patent. Reference 2.). According to this method, it is said that it is possible to provide a head-up display that can be used without causing a malfunction even in an environment in which sunlight is continuously irradiated.

However, the method disclosed in Patent Document 2 has a problem that it is difficult to adjust the retardation value because a polyester resin is used as the thermoplastic resin in the production of the laminated film applied to the head-up display. ing. Further, Patent Document 2 does not disclose the technical idea of combining an infrared absorbing layer containing an infrared absorbing agent and an infrared reflecting layer.

Further, in Patent Document 3, a multilayer laminated film configured by alternately laminating 50 or more layers of two or more kinds of thermoplastic resins having different optical properties is used, and the retardation value is within a range of 100 to 210 nm. In this method, the average reflectance in the wavelength range of 900 to 1200 nm is 70% or more, and it is possible to block the infrared rays of 750 to 1500 nm of solar energy. Not not.

Further, Patent Document 4 discloses a heat-shielding laminate film having an infrared absorbing layer containing an infrared absorbing agent and a resin, and a dielectric multilayer film in which a low refractive index layer and a high refractive index layer are alternately laminated. Has been done. However, even in the method disclosed in Patent Document 4, the polyester resin is used as the resin base material, and the retardation value cannot be adjusted. Therefore, it is not suitable for head-up display applications.

International Publication No. 2016/152843 JP, 2017-129861, A Japanese Patent No. 6291830 International Publication No. 2016/010049

The present invention has been made in view of the above problems, and its problem to be solved is to realize a low phase difference, high durability and high transparency of a gate cover, improvement of heat resistance of a liquid crystal display device, and a display image. It is an object of the present invention to provide a gate cover for a head-up display, which can improve the visibility and the durability of the entire head-up display system.

In order to solve the above problems, the present inventor shields near-infrared light that causes heat generation inside the head-up display, particularly near-infrared light in the 750 to 1500 nm region in the process of examining the causes of the above problems. It was found that high durability of the gate cover can be realized by providing the gate cover with an infrared absorbing layer containing two specific infrared absorbing agents and further providing an infrared reflecting layer. Furthermore, the head-up display provided with this gate cover is excellent in durability because it can significantly suppress heat generation inside the head-up display.
That is, the above-mentioned subject concerning the present invention is solved by the following means.

1. A gate cover for a head-up display in which an infrared absorption layer and an infrared reflection layer are provided on a resin substrate,
The in-plane retardation value of the resin base material is in the range of 0 nm or more and less than 100 nm when a light beam having an incident angle of 0° and a wavelength of 550 nm is incident.
The infrared absorbing layer contains the following infrared absorbent-1 and infrared absorbent-2,
A gate cover for a head-up display, which has an average transmittance of 80% or more in a visible light wavelength region of 380 to 740 nm and an average reflectance of 15% or more in a near infrared wavelength region of 750 to 1500 nm.
(Infrared absorber)
Infrared absorbing agent-1: Near infrared absorbing organic compound infrared absorbing agent having a maximum absorption peak in the near infrared wavelength region of 750 to 1200 nm-2: Metal oxide infrared absorbing agent

2. The gate cover for a head-up display according to item 1, wherein the near-infrared absorber-1 is selected from metal complex dyes, immonium dyes, diimmonium dyes, and polymethine dyes.

3. The infrared absorber-2 is selected from tin-doped indium oxide (ITO), cesium-doped tungsten oxide (CWO), antimony-doped tin oxide (ATO), gallium-doped zinc oxide (GZO) and aluminum-doped zinc oxide (AZO). A gate cover for a head-up display according to claim 1 or 2.

4. The value of the mass ratio of the infrared absorbing agent-2 to the infrared absorbing agent-1 is within a range of 1.0 to 6.0. Gate cover for head-up display described in.

5. Furthermore, it has a polarizing layer, and the average transmittance of linearly polarized light in the visible light wavelength region of 380 to 740 nm is 80% or more. Gate cover for the head-up display described.

6. The gate cover for a head-up display according to any one of items 1 to 5, wherein the infrared reflective layer has a dielectric multilayer film structure.

7. 7. The head-up display gate cover according to any one of items 1 to 6, wherein the infrared reflective layer contains inorganic fine particles.

8. A layer containing the infrared absorbent-2 layer, the infrared reflective layer, and a layer containing the infrared absorbent-1 are arranged in this order on the resin substrate. The gate cover for a head-up display according to any one of items 1 to 7.

9. The head-up display gate cover according to any one of items 1 to 8, which is provided in a head-up display mounted on an automobile, a train, an aircraft, or a ship.

By the above means of the present invention, a low phase difference is realized, the gate cover is made highly durable and highly transparent, the heat resistance of the liquid crystal display device is improved, the visibility of the displayed image and the durability of the entire head-up display system are improved. A gate cover for a head-up display that can be improved can be provided.
Although the mechanism of action or mechanism of action of the present invention has not been clarified, it is presumed as follows.

In a head-up display, it is considered that sunlight is incident on the device, the sunlight is condensed on the liquid crystal display device, and the liquid crystal display device is deteriorated due to heat generation. Conventionally, of the sunlight components, infrared light is cut by the reflective layer on the gate cover and the cold mirror inside the device, and visible light is cut by the polarizing layer attached to the gate cover, so that the heat of the liquid crystal display device by sunlight It suppresses deterioration. In the present invention, in particular, in order to shield near infrared rays in the 750 to 1500 nm region, an infrared reflecting layer is provided to suppress heat generation of the gate cover, and an infrared absorbing layer containing two specific infrared absorbing agents. It is presumed that this is because by providing the gate cover to the gate cover, infrared light entering the head-up display can be reduced and heat generation can be suppressed.

It is assumed that the following four items are the reasons why the task could be achieved.
The first effect is that the rainbow unevenness of the projected image can be suppressed by adopting a resin base material having a low retardation value of an in-plane retardation value of 0 nm or more and less than 100 nm.

The second effect is that, unlike the infrared absorption layer, the infrared reflection layer itself has a characteristic that it does not generate heat due to light reflection. By providing the infrared reflection layer together with the infrared absorption layer, heat generation of the entire gate cover is achieved. Was suppressed, and peeling of the adhesive layer and deterioration of the function of the polarizing layer could be suppressed. In addition, it was possible to improve the durability of the infrared absorbing agent forming the infrared absorbing layer applied.

The third effect is that light in the wavelength range of 750 to 1500 nm among infrared rays has a bad influence on the heat trap. Therefore, by effectively reflecting the infrared rays in this wavelength range, the influence of heat on the TFT-LCD is reduced. It was possible to improve the durability.

The fourth effect is that by providing the infrared reflecting layer and the infrared absorbing layer in combination, the amount of the infrared absorbing agent used can be reduced, and as a result, the light transmittance in the visible light wavelength region can be improved. I'm guessing it was done.

Furthermore, since the heat shield effect can be increased, the configuration including the polarizer of the gate cover and the cold mirror in the head-up display is not necessarily required, and the degree of freedom in design can be improved and various functions can be provided. It is believed that the above head-up display can be formed.

Schematic diagram showing the basic structure of the head-up display and the incident path of sunlight Schematic sectional view showing an example of the basic configuration of a gate cover for a head-up display Schematic sectional view showing an example of the configuration of a polarizing plate applicable to the kate cover of the present invention. Schematic cross-sectional view showing a configuration example 1 of a gate cover for a head-up display manufactured in an example (Embodiment 1) Schematic cross-sectional view showing a configuration example 2 of the gate cover for a head-up display produced in the example (Embodiment 2) Schematic diagram showing an example of the basic configuration of a liquid crystal display device (LCD)

The head-up display gate cover of the present invention is a head-up display gate cover in which an infrared absorbing layer and an infrared reflecting layer are provided on a resin substrate, and the in-plane retardation value of the resin substrate is When the light having an incident angle of 0° and a wavelength of 550 nm is incident, it is in the range of 0 nm or more and less than 100 nm, and the infrared absorbing layer contains the infrared absorbing agent-1 and the infrared absorbing agent-2, The average transmittance in the visible light wavelength region of 380 to 740 nm is 80% or more, and the average reflectance in the near infrared wavelength region of 750 to 1500 nm is 15% or more. This feature is a technical feature common to or corresponding to each of the following embodiments (forms).

As an embodiment of the present invention, from the viewpoint of exhibiting the effect of the present invention, the near-infrared absorber-1 is preferably selected from a metal complex dye, an immonium dye, a diimmonium dye, and a polymethine dye. ..
Further, in the present invention, the infrared absorbent-2 is tin-doped indium oxide (ITO), cesium-doped tungsten oxide (CWO), antimony-doped tin oxide (ATO), gallium-doped zinc oxide (GZO) and aluminum-doped zinc oxide. It is preferably selected from (AZO).

From the viewpoint of increasing the infrared shielding effect of the gate cover and increasing the transmittance in the visible light wavelength region, the value of the mass ratio of the infrared absorbent-2 to the infrared absorbent-1 is 1. It is preferably in the range of 0 to 6.0.
In the present invention, it is preferable that the polarizing plate further has a polarizing layer, and the average transmittance of linearly polarized light in the visible light wavelength region of 380 to 740 nm is 80% or more. Thereby, it is possible to reduce the incident light from the sunlight in the visible light wavelength region into the head-up display without significantly reducing the amount of light emitted from the head-up display.
Furthermore, in the present invention, it is preferable that the infrared reflective layer has a dielectric multilayer film structure.

Further, in the present invention, it is preferable that the infrared reflective layer contains inorganic fine particles.
Further, in the present invention, the layer containing the infrared absorbent-2, the infrared reflective layer, and the layer containing the infrared absorbent-1 are preferably arranged in this order.
INDUSTRIAL APPLICABILITY The gate cover of the present invention can be suitably installed in a head-up display mounted on an automobile, a train, an aircraft or a ship.

Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail with reference to the drawings. In addition, "-" shown in the following description is used to mean that the numerical values described before and after the "-" are included as the lower limit value and the upper limit value. Further, in the following description, the numbers in parentheses after each component represent the reference numerals of each component shown in each drawing.

<<Overview of gate cover for head-up display>>
The head-up display gate cover of the present invention is a head-up display gate cover in which an infrared absorbing layer and an infrared reflecting layer are provided on a resin substrate, and the in-plane retardation value of the resin substrate is When the light having an incident angle of 0° and a wavelength of 550 nm is incident, it is in the range of 0 nm or more and less than 100 nm, and the infrared absorbing layer contains the infrared absorbing agent-1 and the infrared absorbing agent-2, The average transmittance in the visible light wavelength region of 380 to 740 nm is 80% or more, and the average reflectance in the near infrared wavelength region of 750 to 1500 nm is 15% or more.

First, an outline of a head-up display equipped with the head-up display gate cover of the present invention will be described.

FIG. 1 is a schematic diagram showing a basic structure of a head-up display and an incident path of sunlight.
As shown in FIG. 1, in a head-up display 1 installed in front of a driver's seat of an automobile or the like, sunlight L incident from a windshield 2 passes through a head-up display gate cover 3 of the present invention and has a concave surface. The light is condensed by a certain magnifying glass 4, near infrared rays or infrared rays are partially cut by a cold mirror 5 and a hot mirror 6, and the light is incident on a liquid crystal display device 7. In addition, in the following description, the liquid crystal display device 7 may be simply referred to as a “light source”.

In the conventional head-up display, the heat ray is cut by the cold mirror 5 and the hot mirror 6, but as a measure against the increase in the incident amount of heat ray accompanying the increase in the opening area of the gate cover accompanying the increase in projection information, Due to the shortage, the gate cover 3 for a head-up display of the present invention can realize a high visible light transmittance and can also obtain an excellent average reflectance in the near infrared wavelength region, and as a result, in the device. It is possible to suppress heat buildup and the like, and improve the durability of the liquid crystal display device 7.

<Basic configuration of gate cover for head-up display>
The gate cover for a head-up display of the present invention has at least an infrared absorption layer and an infrared reflection layer on a resin substrate. As the infrared absorbing layer, two layers of an infrared absorbing layer A (IR absorbing layer A) and an infrared absorbing layer B (IR absorbing layer B) can be provided. Preferably, the infrared absorption layer B, the infrared reflection layer, and the infrared absorption layer A are arranged in this order from the LCD (also referred to as a light source) side having the built-in head-up display. It is preferable that the infrared absorbing layer A contains an infrared absorbing agent-1 and the infrared absorbing layer B contains an infrared absorbing agent-2.

FIG. 2 is a schematic cross-sectional view showing an example of the basic configuration of the head-up display gate cover of the present invention. The configuration shown in FIG. 2 is a schematic diagram schematically showing the relative relationship between the HUD 7 and the HUD gate cover 3 in FIG. The configuration shown in FIG. 2 is an example, and the present invention is not limited to this.
In FIG. 2, the upper surface side of the paper surface is the incident side of sunlight, and the light source 7 of the head-up display is arranged on the lower surface side. From the light source side, the infrared absorption layer B represented by the resin base materials 11 and 12 The infrared reflecting layer and the infrared absorbing layer A represented by 18 are arranged in this order to form the head-up display gate cover 3.

The gate cover as referred to in the present invention is an exit portion that is included in a head-up display and emits image information from the device, and is usually a transparent resin molding. The transparent resin molded body also has a function of preventing dust and dirt from entering the device.

The “resin base material” in the present invention refers to a resin member having rigidity to the extent that it can support the infrared absorbing layer, the infrared reflecting layer and the polarizing layer according to the present invention.
The “infrared reflecting layer” has a function of reflecting light having a wavelength range from near infrared to infrared region (for example, at least a light wavelength range of 750 to 1500 nm) composed of a dielectric multilayer film, and has a thickness of 750 to 750. A layer having an average reflectance of 15% or more in the near infrared wavelength region of 1500 nm.

The "infrared absorbing layer" specifically includes the infrared absorbing agent-1 (near infrared absorbing organic compound having a maximum absorption peak in the near infrared wavelength region of 750 to 1200 nm) and near infrared absorbing agent-2. A functional layer that contains two kinds of (metal oxide infrared absorber) and absorbs light having a wavelength in the near infrared to infrared region (for example, at least a light wavelength range of 750 to 1500 nm). The infrared absorption layer may be composed of a plurality of layers as described above.

<<Gate cover components>>
Next, details of the resin base material, the infrared absorption layer, the infrared reflection layer, and other constituent elements that constitute the gate cover of the present invention will be described.

[1: resin base material]
The resin base material applied to the gate cover of the present invention is characterized in that the in-plane retardation value R _O is 0 nm or more and less than 100 nm when a light beam having an incident angle of 0° and a wavelength of 550 nm is incident. .. Although not particularly limited, a transparent resin base material is preferable.

Examples of the resin material constituting the resin base material applicable to the present invention include polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (abbreviation: TAC), cellulose acetate butyrate, cellulose acetate propionate (abbreviation: CAP), cellulose acetate phthalate, cellulose esters such as cellulose nitrate and derivatives thereof, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate (abbreviation: PC), norbornene resin, polymethylpentene, Polyetherketone, polyimide, polyethersulfone (abbreviation: PES), polyphenylene sulfide, polysulfones, polyetherimide, polyetherketone imide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic resin and polyarylate resin, Arton ( Examples thereof include cycloolefin-based resins such as trade name, manufactured by JSR) and Apel (trade name, manufactured by Mitsui Chemicals, Inc.).

Among these resin base materials, a resin base material having a triacetyl cellulose (TAC), a cycloolefin resin, a polycarbonate (PC) resin, an acrylic resin and a polyarylate as a resin component has a desired in-plane retardation value R. It is preferable in that _O can be obtained.

The resin contained in the resin base material applied to the present invention may be one kind or a combination of two or more kinds, and the resin base material for forming the gate cover is A plurality of one type of resin base material may be used, or a plurality of different types of resin base material may be used.

(In-plane retardation value R _{O of} resin substrate)
In the resin base material used in the present invention, in order to have a function as a retardation film, the in-plane retardation value R _O when a light beam having an incident angle of 0° and a wavelength of 550 nm is incident is 0 nm or more and less than 100 nm. Is one of the features.

The in-plane retardation value Ro of the resin substrate according to the present invention is defined by the following formula (1).
Equation _{(1): Ro = (n} x -n y) × d
In the formula (1), n _x is the refractive index in the direction x (in-plane slow axis direction) where the refractive index is maximum in the in-plane direction of the film, and n _y is the above-mentioned direction x in the in-plane direction of the film. It is the refractive index in the direction y orthogonal to the (in-plane slow axis direction), and d is the film thickness (nm) of the film.

The in-plane retardation value Ro of the resin substrate according to the present invention can be measured by the following method.
1) The resin base material is conditioned at 23° C. and 55% RH for 24 hours.
2) The in-plane retardation value Ro of the resin substrate after humidity adjustment at an incident angle of 0° and a measurement wavelength of 550 nm was measured at 23° C. and 55% RH by using an automatic birefringence meter “Axoscan” manufactured by Axometrics. Measure under the environment.

The in-plane retardation value Ro of the resin base material is mainly selected from the type of thermoplastic resin constituting the resin base material, the type and content of the alkylene oxide adduct of sugar used as an additive, and film formation. The in-plane retardation value Ro can be adjusted to a desired value by setting the stretching ratio at that time. As a specific example for setting the in-plane retardation value Ro of the resin substrate to a low condition of 0 nm or more and less than 100 nm, for example, a mixture of cellulose acylate and an acrylic resin is selected as the thermoplastic resin, Reduce the number of moles of alkylene oxide added to the alkylene oxide adduct of sugar, change the type of alkylene oxide to an alkylene oxide with a small number of carbon atoms, unblock the hydroxy group end of alkylene oxide, and lower the draw ratio. A desired in-plane retardation value Ro can be obtained by appropriately selecting or combining means for adjusting the values.

Next, details of cellulose acylate, acrylic resin, cycloolefin resin, and polycarbonate resin will be described as typical examples of the thermoplastic resin constituting the resin substrate.

<Cellulose acylate>
Cellulose acylate is a resin in which some or all of the hydroxy groups of cellulose are obtained by an esterification reaction with a carboxylic acid. The acyl group contained in the cellulose acylate may be one kind or a combination of two or more kinds.

The acyl group contained in the cellulose acylate may be an aliphatic acyl group or an aromatic acyl group. Among them, the acyl group contained in the cellulose acylate is preferably an aliphatic acyl group because the retardation can be easily adjusted.

The number of carbon atoms of the aliphatic acyl group is preferably in the range of 2-7, more preferably 2-4. Examples of the aliphatic acyl group include an acetyl group, a propionyl group and a butanoyl group.

Among them, the acyl group of cellulose acylate preferably contains an acetyl group from the viewpoint of easily increasing heat resistance, and may further contain an acyl group having 3 or more carbon atoms, if necessary. The acyl group having 3 or more carbon atoms can impart hydrophobicity to the cellulose acylate.

Examples of cellulose acylate include cellulose acetate (cellulose diacetate (abbreviation: DAC), cellulose triacetate (abbreviation: TAC), etc.), cellulose acetate propionate (abbreviation: CAP), cellulose acetate butyrate, and the like. Cellulose acetate and cellulose acetate propionate are preferable because they hardly cause retardation and have good heat resistance.

The total degree of substitution of acyl groups in cellulose acylate is preferably in the range of 2.0 to 3.0, more preferably in the range of 2.6 to 3.0. By increasing the total degree of substitution of the acyl groups, the retardation developability by stretching can be lowered. The substitution degree of the acyl group can be measured according to ASTM-D817-96.

Specifically, cellulose triacetate or cellulose acetate propionate satisfying the following formulas (1) to (3) is preferable. In the formula, X represents the substitution degree of the acetyl group, and Y represents the substitution degree of the propionyl group.

Formula (1) 1.0≦X≦3.0
Formula (2) 0≦Y≦1.5
Formula (3) 2.0≦X+Y≦3.0
The number average molecular weight Mn of cellulose acylate is preferably in the range of 30,000 to 150,000. When the number average molecular weight Mn of the cellulose acylate is 30,000 or more, the mechanical strength of the resin substrate is easily obtained, and when it is 150,000 or less, the moldability is not easily impaired. The ratio (Mw/Mn) of the weight average molecular weight Mw and the number average molecular weight Mn of cellulose acylate may be about 1.4 to 3.0.

<Acrylic resin>
The acrylic resin may be a homopolymer of (meth)acrylic acid ester; or a copolymer of (meth)acrylic acid ester and another monomer copolymerizable therewith. The (meth)acrylic acid ester includes both acrylic acid ester and methacrylic acid ester.
The (meth)acrylic acid ester is preferably a (meth)acrylic acid alkyl ester, and more preferably methyl methacrylate.

Examples of the other monomer copolymerizable with methyl (meth)acrylate include a methacrylic acid alkyl ester having an alkyl portion having 2 to 18 carbon atoms; an acrylic acid alkyl ester having an alkyl portion having 1 to 18 carbon atoms. Α,β-unsaturated acids such as acrylic acid and methacrylic acid; unsaturated group-containing divalent carboxylic acids such as maleic acid, fumaric acid, and itaconic acid; aromatic vinyl such as styrene, α-methylstyrene, and nucleus-substituted styrene Compounds; α,β-unsaturated nitriles such as acrylonitrile and methacrylonitrile; acid anhydrides such as maleic anhydride and glutaric anhydride; maleimides, N-substituted maleimides and the like. These other monomers may be used alone or in combination of two or more.

The content ratio of the structural unit derived from methyl methacrylate in the copolymer of the (meth)acrylic acid ester and the other monomer copolymerizable therewith is 30 mol based on the total of all the structural units constituting the copolymer. % Or more, and more preferably 50 mol% or more.
Examples of acrylic resins include polymethylmethacrylate and the like.

The weight average molecular weight Mw of the acrylic resin is preferably in the range of 80,000 to 1,000,000. When the weight average molecular weight Mw of the acrylic resin is 80,000 or more, the mechanical strength of the resin base material is easily obtained, and when it is 1,000,000 or less, the moldability is not easily impaired. The weight average molecular weight Mw of the acrylic resin can be measured by the same method as described above.

<Cycloolefin resin>
The cycloolefin-based resin is a polymer of cycloolefin monomers or a copolymer of cycloolefin monomers and other copolymerizable monomers.
The cycloolefin monomer is a cycloolefin monomer having a norbornene skeleton. From the viewpoint of obtaining a resin base material having a low retardation value Ro or Rt (retardation value in the thickness direction), it is preferable to include a cycloolefin monomer having an asymmetric structure. Examples of the cycloolefin monomer having an asymmetric structure include the cycloolefin monomer represented by the following general formula (A-1).

R ₁ in the general formula (A-1) represents a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms, or an alkylsilyl group having an alkyl group having 1 to 5 carbon atoms. Especially, a C1-C5 hydrocarbon group is preferable and a C1-C3 hydrocarbon group is more preferable.

R ₂ in the general formula (A-1) represents a carboxy group, a hydroxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amide group, a cyano group, or a halogen atom (a fluorine atom, a chlorine atom, a bromine atom or iodine). Atom). Of these, a carboxy group, a hydroxy group, an alkoxycarbonyl group and an aryloxycarbonyl group are preferable, and an alkoxycarbonyl group and an aryloxycarbonyl group are more preferable from the viewpoint of ensuring the solubility during solution film formation.

P in the general formula (A-1) represents an integer of 0 to 2, and is preferably 1 or 2.
The cycloolefin monomer represented by the general formula (A-1) has an asymmetric structure. That is, since the substituents R ₁ and R _{2 of the} cycloolefin monomer represented by the general formula (A-1) are each substituted only on the ring-constituting carbon atom on one side with respect to the symmetry axis of the molecule, The symmetry of the molecule is low. In the cycloolefin monomer having such an asymmetric structure, even if the main chains are arranged in the x direction, the side chains are oriented not only in the xy plane but also in various other directions, so that only Ro is easily expressed, It is considered that Rt does not easily increase.

The content ratio of the cycloolefin monomer represented by the general formula (A-1) is, for example, 50 mol% or more, preferably 50 mol% or more, based on the total of all cycloolefin monomers constituting the cycloolefin polymer. It may be 60 mol% or more, more preferably 80 mol% or more. The cycloolefin polymer containing a certain amount or more of the monomer represented by formula (A-1) easily lowers the Rt of the resin base material.

The cycloolefin monomer may further include another cycloolefin monomer other than the cycloolefin monomer represented by the general formula (A-1), if necessary. Examples of other cycloolefin monomers include cycloolefin monomers represented by the following general formula (A-2).

R _{3 to} R ₆ in formula (A-2) independently represent a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a polar group. However, all of R _{3 to} R ₆ do not represent hydrogen atoms at the same time, R ₃ and R ₄ do not represent hydrogen atoms at the same time, and R ₅ and R ₆ do not represent hydrogen atoms at the same time. To do.

The hydrocarbon group having 1 to 30 carbon atoms is preferably a hydrocarbon group having 1 to 10 carbon atoms, and more preferably a hydrocarbon group having 1 to 5 carbon atoms. The hydrocarbon group having 1 to 30 carbon atoms may further have a connecting group containing a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom or a silicon atom. Examples of such a connecting group include a carbonyl group, an imino group, a divalent polar group such as an ether bond, a silyl ether bond and a thioether bond. Examples of the hydrocarbon group having 1 to 30 carbon atoms include methyl group, ethyl group, propyl group, butyl group and the like.

Examples of the polar group include a carboxy group, a hydroxy group, an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amide group and a cyano group. Among them, a carboxy group, a hydroxy group, an alkoxycarbonyl group and an aryloxycarbonyl group are preferable, and an alkoxycarbonyl group and an aryloxycarbonyl group are preferable from the viewpoint of ensuring the solubility during solution film formation.
P in the general formula (A-2) represents an integer of 0 to 2, and is preferably 1 or 2.

Specific examples of the cycloolefin monomer represented by the general formula (A-1) and the general formula (A-2) include, for example, paragraph (0028) of JP2018-072503A and JP2018-080211A. Exemplary compounds 1 to 34 described in paragraph (0063) of the publication can be mentioned.
Examples of other cycloolefin monomers also include dicyclopentadiene, dihydrodicyclopentadiene and the like.

Examples of copolymerizable monomer that can be copolymerized with cycloolefin monomer include copolymerizable monomer that can be ring-opening copolymerized with cycloolefin monomer, and addition copolymerizable with cycloolefin monomer. Such copolymerizable monomers are included.

Examples of the ring-opening copolymerizable copolymerizable monomer include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclohexene, cyclooctene, cyclopentadiene, cyclohexadiene, cycloheptadiene and cyclooctadiene.

Examples of copolymerizable monomers capable of addition copolymerization include unsaturated double bond-containing compounds, vinyl cyclic hydrocarbon monomers, and (meth)acrylates. An example of the unsaturated double bond-containing compound is an olefin compound having 2 to 12 carbon atoms (preferably 2 to 8), and examples thereof include ethylene, propylene and butene. Examples of vinyl-based cyclic hydrocarbon monomers include vinyl-cyclopentene-based monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene. Examples of the (meth)acrylate include alkyl(meth)acrylates having 1 to 20 carbon atoms such as methyl(meth)acrylate, 2-ethylhexyl(meth)acrylate and cyclohexyl(meth)acrylate.

The content ratio of the cycloolefin-based resin in the cycloolefin-based resin is, for example, in the range of 50 to 100 mol%, preferably 60 to 100 mol% with respect to the total of all the monomers constituting the cycloolefin-based resin. Can be within the range.

The number average molecular weight Mn of the cycloolefin polymer is preferably in the range of 8,000 to 100,000, more preferably in the range of 10,000 to 80,000, and further preferably in the range of 12,000 to 50,000. The weight average molecular weight Mw of the cycloolefin polymer is preferably in the range of 20,000 to 300,000, more preferably in the range of 30,000 to 250,000, and even more preferably in the range of 40,000 to 200,000. The number average molecular weight Mn and the weight average molecular weight Mw of the cycloolefin polymer can be measured by the same method as described above.

<Polycarbonate resin>
Various known polycarbonate-based resins can also be used as the resin base material according to the present invention. In the present invention, it is particularly preferable to use aromatic polycarbonate. There are no particular restrictions on the aromatic polycarbonate, and there is no particular restriction as long as it is an aromatic polycarbonate that provides the desired properties of the resin substrate.

Generally, polymer materials generally referred to as polycarbonates are those in which the main chain is bound by a carbonic acid bond using a known polycondensation reaction. Among these, generally, a phenol derivative, phosgene and diphenyl are used. It means a product obtained by polycondensation from carbonates or the like. Usually, an aromatic polycarbonate represented by a repeating unit having a bisphenol component of 2,2-bis(4-hydroxyphenyl)propane, which is called bisphenol-A, is preferably selected, but various bisphenol derivatives should be appropriately selected. Then, an aromatic polycarbonate copolymer can be constituted.

As such a copolymerization component, in addition to bisphenol-A, bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 9,9-bis(4-hydroxyphenyl)fluorene, 1,1 -Bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxyphenyl)-2-phenyl Ethane, 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane, bis(4-hydroxyphenyl)diphenylmethane, bis(4-hydroxyphenyl)sulfide, bis( 4-hydroxyphenyl) sulfone, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane and the like can be mentioned.

It is also possible to use an aromatic polyester carbonate partially containing a terephthalic acid or isophthalic acid component. By using such a structural unit as a part of the constituent components of the aromatic polycarbonate composed of bisphenol-A, the properties of the aromatic polycarbonate, such as heat resistance and solubility, can be improved. The present invention is also effective for various copolymers.

The viscosity average molecular weight of the aromatic polycarbonate used here is preferably in the range of 10,000 to 200,000, and particularly preferably in the range of 20,000 to 120,000. When a resin having a viscosity average molecular weight of less than 10,000 is used, the mechanical strength of the obtained resin base material may be insufficient, and when the polymer has a high molecular weight of more than 200,000, the viscosity of the dope during film formation becomes too high. This is not preferable because it causes problems. The viscosity average molecular weight can be measured by a commercially available high performance liquid chromatography or the like.

The glass transition temperature of the aromatic polycarbonate used in the present invention is preferably 200° C. or higher in order to obtain a highly heat resistant film, and more preferably 230° C. or higher. These can be obtained by appropriately selecting the copolymerization component. The glass transition temperature can be measured by a DSC device (differential scanning calorimeter), for example, RDC220 manufactured by Seiko Instruments Inc., which is obtained by a temperature rising condition of 10° C./min. It is the temperature that begins to change from the side.

The thermoplastic resin applied to the production of the resin base material is preferably cellulose acylate from the viewpoint of suitability for processing into a polarizing plate. A combination of cellulose acylate and an acrylic resin is also preferable from the viewpoint of easily reducing the phase difference and easily balancing the moisture resistance and the heat resistance. Acrylic resins and cycloolefin resins are preferable from the viewpoint of easily increasing the moisture resistance. Further, from the viewpoint of transparency and strength, polycarbonate resin is preferable.
The content of the thermoplastic resin in the resin substrate may be 50% by mass or more, preferably 70% by mass or more, based on the total mass of the resin substrate.

(Other additives of resin base material)
The resin base material according to the present invention may further contain components other than those described above, if necessary. Examples of other components include ultraviolet absorbers, plasticizers, antioxidants and matting agents.

(UV absorber)
The ultraviolet absorber may be added for the purpose of improving the weather resistance of the resin base material. Examples of such UV absorbers include benzotriazole-based UV absorbers, benzophenone-based UV absorbers, salicylate-based UV absorbers, cyanoacrylate-based UV absorbers, and triazine-based UV absorbers.

Examples of the benzotriazole-based ultraviolet absorber include 5-chloro-2-(3,5-di-sec-butyl-2-hydroxylphenyl)-2H-benzotriazole and (2-2H-benzotriazol-2-yl). )-6-(Straight and side chain dodecyl)-4-methylphenol. Examples of commercially available benzotriazole-based UV absorbers include TINUVIN series such as TINUVIN109, TINUVIN171, TINUVIN234, TINUVIN326, TINUVIN327, TINUVIN328, and TINUVIN928, all of which are commercial products manufactured by BASF.

Examples of the benzophenone-based UV absorber include 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxy-5-. Sulfobenzophenone, bis(2-methoxy-4-hydroxy-5-benzoylphenylmethane) and the like are included.

Examples of salicylic acid ester-based UV absorbers include phenyl salicylate, p-tert-butyl salicylate, and the like.

Examples of the cyanoacrylate-based ultraviolet absorber are 2'-ethylhexyl-2-cyano-3,3-diphenyl acrylate, ethyl-2-cyano-3-(3',4'-methylenedioxyphenyl)-acrylate, and the like. Is included.

Examples of the triazine-based ultraviolet absorber include 2-(2'-hydroxy-4'-hexyloxyphenyl)-4,6-diphenyltriazine and the like. Examples of commercially available triazine-based UV absorbers include TINUVIN 477 (manufactured by BASF).

Among these, the triazine-based UV absorbers are preferable in that they have a good UV-absorbing ability, but they tend to exhibit a retardation by stretching. Therefore, the benzotriazole-based UV absorber and the benzophenone-based UV absorber are preferable, and the benzotriazole-based UV absorber is more preferable, in that the retardation hardly occurs due to stretching and the UV absorbing performance is good.

The content of the ultraviolet absorber is preferably within the range of 0.1 to 10 mass% with respect to the total mass of the thermoplastic resin. When the content of the ultraviolet absorber is 0.1% by mass or more based on the total mass of the thermoplastic resin, the weather resistance of the resin base material can be sufficiently enhanced. When the content of the ultraviolet absorber is 10% by mass or less based on the total mass of the thermoplastic resin, the transparency of the obtained resin base material is hard to be impaired. The content of the ultraviolet absorber is more preferably 0.5 to 10% by mass, further preferably 1.5 to 5% by mass, based on the total mass of the thermoplastic resin.

(Plasticizer)
Examples of plasticizers include polyester plasticizers, polyhydric alcohol ester plasticizers, polycarboxylic acid ester plasticizers (including phthalic acid ester plasticizers), glycolate plasticizers, ester plasticizers ( Fatty acid ester-based plasticizers), acrylic plasticizers, and the like. The plasticizer contained in the protective film may be one kind or a combination of two or more kinds. Among them, polyester-based plasticizers are preferable because they are easily compatible with the thermoplastic resin and good plasticity is easily obtained.
The polyester plasticizer is preferably represented by the following formula (I). N in the following formula (I) represents an integer of 1 or more.

Formula (I): B-(GA) _n -GB
A in the formula (I) represents a group derived from an alkylenedicarboxylic acid having 4 to 12 carbon atoms, a group derived from an alkenylene dicarboxylic acid, or a group derived from an aryl dicarboxylic acid having 6 to 12 carbon atoms.

Examples of groups derived from alkylenedicarboxylic acid include 1,2-ethanedicarboxylic acid (succinic acid), 1,3-propanedicarboxylic acid (glutaric acid), 1,4-butanedicarboxylic acid (adipic acid), 1 , 5-pentanedicarboxylic acid (pimelic acid), 1,8-octanedicarboxylic acid (sebacic acid) and the like are included. Examples of the group derived from alkenylene dicarboxylic acid include groups derived from maleic acid, fumaric acid and the like. Examples of the group derived from the aryldicarboxylic acid include 1,2-benzenedicarboxylic acid (phthalic acid), 1,3-benzenedicarboxylic acid, 1,4-benzenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid and the like. Induced groups are included.

G in the formula (I) is derived from an alkylene glycol having 2 to 12 carbon atoms, a group derived from an aryl glycol having 6 to 12 carbon atoms, or an oxyalkylene glycol having 4 to 12 carbon atoms. Represents a group.

Examples of the group derived from an alkylene glycol having 2 to 12 carbon atoms include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1 ,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2 ,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3-methyl -1,5-Pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8-octane Included are groups derived from diols, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol and the like.

Examples of the group derived from an aryl glycol having 6 to 12 carbon atoms include 1,2-dihydroxybenzene (catechol), 1,3-dihydroxybenzene (resorcinol), and 1,4-dihydroxybenzene (hydroquinone). Included groups. Examples of the group derived from oxyalkylene glycol having 4 to 12 carbon atoms include groups derived from diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and the like.

The G may be one type or a combination of two or more types. Among them, G is preferably a group derived from alkylene glycol having 2 to 12 carbon atoms.
B in the formula (I) is a group derived from an aromatic ring-containing monocarboxylic acid or an aliphatic monocarboxylic acid.

Aromatic ring-containing monocarboxylic acid is a carboxylic acid containing an aromatic ring in the molecule, not only those in which the aromatic ring is directly bonded to the carboxy group, but those in which the aromatic ring is bonded to the carboxy group via an alkylene group, etc. Including. Examples of groups derived from aromatic ring-containing monocarboxylic acids include benzoic acid, paratertiarybutylbenzoic acid, orthotoluic acid, metatoluic acid, paratoluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal propylbenzoic acid, aminobenzoic acid. Groups derived from acids, acetoxybenzoic acid, phenylacetic acid, 3-phenylpropionic acid and the like are included.

Examples of groups derived from an aliphatic monocarboxylic acid include groups derived from acetic acid, propionic acid, butanoic acid, caprylic acid, caproic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid and the like. Of these, a group derived from an alkyl monocarboxylic acid having an alkyl moiety having 1 to 3 carbon atoms is preferable, and an acetyl group is more preferable.

Specific examples of the polyester-based plasticizer represented by the formula (I) include Exemplified Compounds I-1 to I-19 described in paragraph (0090) of JP-A-2017-219767.

The weight average molecular weight of the polyester plasticizer is preferably in the range of 500 to 3000. When the weight average molecular weight of the polyester plasticizer is 500 or more, it is difficult to volatilize during film formation, and when it is 3000 or less, moldability and compatibility with the thermoplastic resin are not easily impaired. The weight average molecular weight of the polyester plasticizer is more preferably in the range of 600 to 2000. The weight average molecular weight can be measured, for example, by gel permeation chromatography (GPC).

The content of the plasticizer is preferably in the range of 1 to 40 mass% with respect to the total mass of the thermoplastic resin. When the content of the plasticizer is 1% by mass or more with respect to the total mass of the thermoplastic resin, the resin substrate is easily plasticized sufficiently when it is made into a film, and when it is 40% by mass or less, the resin group Bleed out during stretching and storage of the material can be easily suppressed. The content of the plasticizer is more preferably in the range of 1 to 20% by mass and further preferably in the range of 1 to 3% by mass with respect to the total mass of the thermoplastic resin.

(Antioxidant)
The antioxidant is for the purpose of suppressing deterioration of the resin base material placed under high humidity and high temperature, and specifically, the resin due to halogen of the residual solvent amount in the resin base material or phosphoric acid of the phosphoric acid plasticizer. It may be added for the purpose of delaying or suppressing the decomposition of components.

As the antioxidant, a hindered phenol compound is preferably used, and examples thereof include 2,6-di-t-butyl-p-cresol and pentaerythrityl-tetrakis[3-(3,5-di). -T-Butyl-4-hydroxyphenyl)propionate], triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3 -(3,5-Di-t-butyl-4-hydroxyphenyl)propionate], 2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)- 1,3,5-triazine, 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t -Butyl-4-hydroxyphenyl)propionate, N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4 , 6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tris-(3,5-di-t-butyl-4-hydroxybenzyl)-isocyanurate and the like. Among them, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], triethylene glycol-bis[3 -(3-t-Butyl-5-methyl-4-hydroxyphenyl)propionate] is preferred.

The content of the antioxidant is preferably in the range of 1 mass ppm to 1.0 mass% with respect to the total mass of the thermoplastic resin, and more preferably in the range of 10 to 1000 mass ppm.

(Matting agent)
The matting agent (hereinafter, also referred to as fine particles) may be added for the purpose of enhancing the slipperiness of the surface of the resin base material. The fine particles are inorganic fine particles or organic fine particles. Examples of the inorganic fine particles include silicon dioxide (silica), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, Fine particles such as magnesium silicate and calcium phosphate are included. Examples of organic fine particles include fine particles of silicone resin, fluororesin, (meth)acrylic resin, and the like. Among them, silicon dioxide (silica) particles are preferable because they hardly cause haze and are less colored.

Examples of fine particles of silicon dioxide include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, NAX50 (all manufactured by Nippon Aerosil Co., Ltd.), Seahoster KE-P10, KE-P30. , KE-P50, KE-P100 (above, manufactured by Nippon Shokubai Co., Ltd.) and the like. Among them, Aerosil R972V, NAX50 and Seahoster KE-P30 are preferable because they can easily reduce the friction coefficient while keeping the turbidity (also referred to as haze) of the obtained film low.

The primary particle size of the fine particles is preferably in the range of 5 to 50 nm, and more preferably in the range of 7 to 20 nm. The larger the primary particle size, the greater the effect of increasing the slipperiness of the obtained film, but the transparency tends to decrease. Therefore, the fine particles may be contained as a secondary aggregate having a particle diameter of 0.05 to 0.3 μm. The size of the primary particles of the fine particles or the secondary aggregate thereof is 100 particles of the primary particles or the secondary aggregates when the primary particles or the secondary aggregates are observed with a transmission electron microscope at a magnification of 50 to 2,000,000 times. It can be obtained as an average value of diameters.
The content of the fine particles is preferably in the range of 0.05 to 1.0 mass% and more preferably 0.1 to 0.8 mass% with respect to the total mass of the thermoplastic resin.

(Method of manufacturing resin base material)
The resin base material used in the present invention can be produced by any method, and the production process includes, for example, (1) a step of obtaining a dope containing at least the above-described thermoplastic resin and a solvent, and (2) ) A step of casting the obtained dope on a metal support, drying and peeling the dope to obtain a film-like material, and (3) a step of stretching the obtained film-like material.

As a production method applicable to the production of the resin base material used in the present invention, a conventionally known film forming method can be applied, for example, JP2013-120278A and JP2015-049331A. , JP-A-2015-132661, JP-A-2017-111264, JP-A-2017-122936, International Publication No. 2015/141340, International Publication No. 2017/110400, and the like. Can be applied.

[2: Infrared absorbing layer]
In the gate cover of the present invention, the infrared absorbing layer is an infrared absorbing agent-1 which is a near infrared absorbing organic compound having a maximum absorption peak in the near infrared wavelength region of 750 to 1200 nm, and a metal oxide infrared absorbing agent. It is characterized by containing two kinds of infrared absorbing agents-2.

Since the infrared rays can be efficiently absorbed over a wide wavelength range of infrared rays by having two kinds as described above, the infrared shielding effect of the gate cover of the present invention can be enhanced.
From the viewpoint of increasing the infrared shielding effect of the gate cover and increasing the transmittance in the visible light wavelength region, the value of the mass ratio of the infrared absorbent-2 to the infrared absorbent-1 is 1.0 to 6 It is preferably in the range of 0.0.

Further, the infrared absorbing agent-1 and the infrared absorbing agent-2 may be contained in one infrared absorbing layer at the same time, or may be contained in a plurality of infrared absorbing layers. When the gate cover has a plurality of infrared absorbing layers, the layer containing the infrared absorbing agent-2, the infrared reflecting layer and the layer containing the infrared absorbing agent-1 are arranged in this order on the resin substrate. Is preferred. It is preferable to install the resin substrate side on the light source side in the head-up display.

In the present invention, the infrared absorbing layer is a layer having the ability to absorb light in the near infrared region of 750 to 2500 nm. Further, the infrared absorption layer may contain other additives in order to impart other functions or improve various characteristics.
Further, an infrared absorbing agent may be contained in the functional layer described later to give the function layer the function of the infrared absorbing layer. For example, the function of the infrared absorbing layer can be imparted by including the infrared absorbing agent in the adhesive layer containing the adhesive. Further, by including an infrared absorbing agent in the hard coat layer, the function of the infrared absorbing layer can be imparted to the hard coat layer.

(Infrared absorber-1)
The infrared absorbent-1 according to the present invention is a near infrared absorbing organic compound having a maximum absorption peak in the range of 750 to 1200 nm. The following compounds can be mentioned as such a thing.

Examples of the near infrared absorbing organic compound applicable to the present invention include nitroso compounds and metal complex salts thereof, polymethine dyes (cyanine type, oxonol type, croconium type, squarylium type, pyrylium type, azrenium type), dithiol complex salt type Compounds, metal complex dyes (copper complexes, phthalocyanine compounds, naphthalocyanine compounds), triallylmethane dyes, immonium dyes, diimmonium dyes, naphthoquinone compounds, anthraquinone compounds, amino compounds, aminium salt compounds, etc. Is mentioned.

Among these, metal complex dyes, immonium dyes, diimmonium dyes, naphthoquinone compounds, anthraquinone compounds, amino compounds, aminium salt compounds, polymethine dyes, or triallylmethane dyes are preferred, more preferably, Metal complex dyes, immonium dyes, diimmonium dyes, aminium salt compounds, polymethine dyes, or triallylmethane dyes, more preferably metal complex dyes, immonium dyes, diimmonium dyes, Alternatively, it is a polymethine dye, and a diimmonium dye or a polymethine dye is particularly preferable. Among the polymethine dyes, croconium dyes, squarylium dyes and pyrylium dyes are preferred.

A commercially available product can be used as the diimmonium salt compound. For example, Kayasorb IRG-022, IRG-023, IRG-024 (above, Nippon Kayaku Co., Ltd.), CIR-1080, CIR-1081, CIR-1083, CIR-1085 (above, Nippon Carlit Co., Ltd.) etc. are suitable. Is.

Specific examples of the near-infrared absorbing dye that can be preferably used include, for example, JP-A 2004-93767, JP-A 2004-69759, JP-A 2002-286931, JP-A 2002-122729, and JP-A 2001-115050. , JP-A-2001-115050, JP-A-2000-162431, JP-A-11-109126, and JP-A-2006-13311, but the present invention is not limited thereto. There is no such thing.

(Measurement of maximum absorption peak)
The maximum absorption peak of the near-infrared absorbing organic compound according to the present invention can be measured using a device capable of measuring infrared spectral absorption such as a spectrophotometer U-4100 (manufactured by Hitachi High-Technologies Corporation). it can. As the measurement solvent, for example, methanol, dimethyl sulfoxide, diacetone alcohol, 1,2-dichloroethane, toluene, methyl ethyl ketone, or the like can be used.

(Infrared absorber-2)
The infrared absorbent-2 according to the present invention is a metal oxide infrared absorbent.
Examples of the metal oxide infrared absorber applicable to the present invention include tin oxide, tin-doped indium oxide (ITO), cesium-doped tungsten oxide (CWO), antimony-doped tin oxide (ATO), gallium-doped zinc oxide (GZO) and Examples thereof include aluminum-doped zinc oxide (AZO), lanthanum hexaboride (LaB ₆ ), zinc oxide, indium-doped zinc oxide (IZO), and nickel complex compounds, but in particular, tin-doped indium oxide (ITO) and cesium-doped. At least one selected from tungsten oxide (CWO), antimony-doped tin oxide (ATO), gallium-doped zinc oxide (GZO), and aluminum-doped zinc oxide (AZO) is preferable.

In addition, these metal oxide infrared absorbers can also be obtained as commercial products. For example, as zinc oxide, Cellunax series (manufactured by Nissan Chemical Industries, Ltd.), Pazette series (manufactured by Hakusui Tech); As the tin oxide type, ATO dispersion liquid (manufactured by SR35M Advanced Nano Products Co., Ltd.), ITO dispersion liquid (manufactured by Mitsubishi Materials Electronics Co., Ltd.), KH series (Sumitomo Metal Mining Co., Ltd.); as cesium-doped tungsten oxide system, CWO Dispersion (YMF-02A manufactured by Sumitomo Metal Mining Co., Ltd.); Examples of the lanthanum hexaboride include LaB ₆ dispersion (KHF-7AH manufactured by Sumitomo Metal Mining Co., Ltd.). The inorganic infrared absorbing agent preferably does not contain any of these specific metals in order to easily control the concentrations (contents) of iron, copper and chromium in the infrared absorbing layer.

Further, as the inorganic infrared absorber, those made of Cd/Se, GaN, Y ₂ O ₃ , Au, Ag and the like can also be used.

The average particle size of the metal oxide infrared absorber is preferably in the range of 5 to 150 nm, more preferably 10 to 120 nm. When the average particle size is 5 nm or more, the dispersibility in the binder resin used for forming the infrared absorbing layer and the infrared absorbing property can be favorably maintained. The decrease in the rate can be suppressed. The average particle size is measured by imaging with a transmission electron microscope, randomly extracting, for example, 50 particles, measuring the particle size, and averaging the measured values. Further, when the shape of the particles is not spherical, it is defined to be calculated by measuring the diameter when converted into a circle equivalent of the same area.

(Binder resin for forming infrared absorption layer)
In the present invention, the infrared absorbing layer preferably contains a binder resin together with the infrared absorbing agent described above. When the infrared absorbing layer containing the infrared absorbing agent according to the present invention constitutes a gate cover, from the viewpoint of imparting a function as an adhesive layer between adjacent layers, an adhesive binder resin may also be used as the binder resin. You can

The binder resin is preferably a water-soluble adhesive resin from the viewpoint of reducing environmental load and process load. The water-soluble adhesive resin is not particularly limited, and examples thereof include polyvinyl alcohol resins, gelatin, celluloses, thickening polysaccharides, and polymers having a reactive functional group. The term "water-soluble" as used in the present invention means that the G2 glass filter (maximum pore size is 40 to 50 µm) when dissolved in water at a temperature at which the substance is most dissolved to have a concentration of 0.5% by mass. It means that the mass of the insoluble matter separated by filtration is within 50 mass% of the added polymer.

Further, from the viewpoint of reducing the influence of humidity fluctuation of the gate cover, it is preferable to contain an organic solvent-soluble adhesive resin. The organic solvent-soluble adhesive resin is not particularly limited, but acrylic resin, urethane-modified acrylic resin, polyurethane resin, polyester resin, melamine resin, polyvinyl acetate, cellulose acetate, polycarbonate, polyacetal, polybutyral, polyamide (nylon) ) Resin, polystyrene resin, polyimide resin, ABS resin, nitrile rubber, polyvinylidene fluoride and the like.

(Solvent of coating solution for forming infrared absorbing layer)
In the present invention, in the formation of the infrared absorbing layer, the solvent used for preparing the coating liquid for forming the infrared absorbing layer is preferably a solvent that can sufficiently disperse or dissolve the binder resin component and the infrared absorbing agent. It is not limited, and various organic solvents and aqueous solvents can be used.

The organic solvent applicable to the present invention is not particularly limited, but examples thereof include alcohols such as methanol, ethanol, n-propanol and i-propanol, esters such as ethyl acetate, butyl acetate and propylene glycol monomethyl ether acetate, Examples thereof include ethers such as diethyl ether and propylene glycol monomethyl ether, amides such as dimethylformamide, and ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone. These organic solvents may be used alone or in combination of two or more. Among the above organic solvents, considering the dispersibility of the resin and the infrared absorber, it is preferable to use esters, ethers and ketones, and more preferable to use ketones.

(Other additives of infrared absorber)
Examples of additives other than those described above for the infrared absorbing layer according to the present invention include amino acids, emulsion resins and lithium compounds. Further, ultraviolet absorbers described in JP-A-57-74193, JP-A-57-87988 and JP-A-62-261476; JP-A-57-74192 and JP-A-57-87989. Anti-fading agents described in JP-A-60-72785, JP-A-61-146591, JP-A-1-95091, JP-A-3-13376, etc.; JP-A-59-42993. Fluorescent brighteners described in JP-A-59-52689, JP-A-62-280069, JP-A-61-242871, JP-A-4-219266, etc.; sulfuric acid, phosphoric acid, PH adjusting agents such as acetic acid, citric acid, sodium hydroxide, potassium hydroxide and potassium carbonate; antifoaming agents; lubricants such as diethylene glycol; preservatives; antifungal agents; antistatic agents; matting agents; heat stabilizers; oxidation. Various known additives such as an inhibitor, a flame retardant, a crystal nucleating agent, an inorganic particle, an organic particle, a viscosity reducing agent, a lubricant, etc. may be used within a range that does not impair the intended effects of the present invention.

(Formation of infrared absorption layer)
The method for forming the infrared absorbing layer according to the present invention is not particularly limited, but it is preferably formed by a wet coating method, for example, a roll coating method, a flow coating method, a spray coating method, a printing method, a dip coating method, A bar coating method, a casting film forming method, an inkjet printing method, a gravure printing method and the like can be mentioned.

[3: Infrared reflective layer]
The gate cover of the present invention has an infrared reflection layer in addition to the infrared absorption layer described above.
In addition, it is a preferable mode that the infrared reflective layer is a dielectric multilayer film, and further that the dielectric multilayer film contains inorganic fine particles.
Hereinafter, details of the dielectric multilayer film which is a preferred embodiment of the infrared reflective layer according to the present invention will be described.

[Dielectric multilayer film]
In the gate cover of the present invention, as the infrared reflective layer, when infrared light having a specific wavelength is incident, at least a part of the infrared light is reflected to exert a heat shielding effect, and thus, has a low refractive index. It is preferable to have a dielectric multilayer film in which a refractive index layer and a high refractive index layer are alternately laminated in multiple layers.

In the dielectric multilayer film according to the present invention, whether the refractive index layer forming the dielectric multilayer film is a low refractive index layer or a high refractive index layer depends on the comparison of the refractive index between the adjacent refractive index layers. To be judged. Specifically, when a refractive index layer is used as a reference layer and the refractive index layer adjacent to the reference layer has a lower refractive index than the reference layer, the reference layer is a high refractive index layer and the adjacent layer has a low refractive index. Become a stratum. On the other hand, when the refractive index of the adjacent layer is higher than that of the reference layer, the reference layer is the low refractive index layer and the adjacent layer is the high refractive index layer. Therefore, whether the refractive index layer is a high refractive index layer or a low refractive index layer is a relative one determined by the relationship with the refractive index of the adjacent layer, and a certain refractive index layer is different from the adjacent layer. Depending on the relationship, it can be a high refractive index layer or a low refractive index layer.

The refractive index layer is not particularly limited, but it is preferable to use a known refractive index layer used in the art. As the known refractive index layer, for example, a refractive index layer formed by a dry film forming method, a refractive index layer formed by extrusion molding of a resin, and a refractive index layer formed by a wet film forming method. Is mentioned. Among them, from the viewpoint of manufacturing efficiency, it is preferable to apply the wet film forming method as the method of forming the refractive index layer.

Hereinafter, of the refractive index layers that can be formed by the wet film formation method, typical configurations of the high refractive index layer and the low refractive index layer will be described.

(Formation of refractive index layer laminate using wet film formation method)
In the wet film forming method, a single layer of coating liquid is sequentially applied and dried to form a laminated body, or a method of forming a laminated body by simultaneous multi-layer coating and drying using a plurality of types of coating liquids. Thereby, a refractive index laminate in which a plurality of refractive index layers are laminated can be formed. The dielectric multilayer film according to the present invention is preferably formed by laminating a low refractive index layer and a high refractive index layer by this wet film forming method.

(High refractive index layer)
From the viewpoint of easy control of the refractive index, the high refractive index layer preferably contains metal oxide particles, and optionally contains a water-soluble resin, a curing agent, a surfactant, and other additives. But it's okay. The metal oxide particles and the water-soluble resin contained in the high refractive index layer are hereinafter referred to as “first metal oxide particles” and “first water-soluble resin”, respectively, for convenience.

(1) First Metal Oxide Particles The first metal oxide particles are not particularly limited, but are preferably metal oxide particles having a refractive index in the range of 2.0 to 3.0. Specifically, titanium oxide, zirconium oxide, zinc oxide, alumina, colloidal alumina, lead titanate, red lead, yellow lead, zinc yellow, chromium oxide, ferric oxide, iron black, copper oxide, magnesium oxide, water. Examples thereof include magnesium oxide, strontium titanate, yttrium oxide, niobium oxide, europium oxide, lanthanum oxide, zircon and tin oxide. Among these, the first metal oxide particles are preferably titanium oxide or zirconium oxide, from the viewpoint of being able to form a transparent high refractive index layer having a high refractive index, and also for improving weather resistance. From the viewpoint, rutile type (tetragonal type) titanium oxide is more preferable.

Further, the titanium oxide may be in the form of core/shell particles coated with a silicon-containing hydrated oxide. The core-shell particles have a structure in which the surface of titanium oxide particles is coated with a shell made of hydrated oxide of silicon-containing titanium oxide serving as a core.
The above-mentioned first metal oxide particles may be used alone or in combination of two or more.

The content of the first metal oxide particles is within the range of 15 to 85 mass% with respect to 100 mass% of the solid content of the high refractive index layer, from the viewpoint that the refractive index difference with the low refractive index layer becomes large. It is preferable that it is in the range of 20 to 80% by mass, and it is particularly preferable that it is in the range of 30 to 77% by mass.

The volume average particle diameter of the first metal oxide particles is preferably within the range of 1 to 100 nm, more preferably within the range of 3 to 50 nm. When the volume average particle size is 1 nm or more, fine particles can be stably formed, and when the volume average particle size is 100 nm or less, haze is small and visible light transmittance is excellent, which is preferable. In the present invention, the value of “volume average particle diameter” shall be the value measured by the following method. Specifically, the particle diameters of 1000 arbitrary metal oxide particles appearing on the cross section and surface of the refractive index layer are observed by an electron microscope to measure the particle diameters of d1, d2...di...dk, respectively. In a group of metal oxide particles having n1, n... Ni... nk particles each having a particle size, when the volume per particle is vi, the volume average particle size mv={Σ A volume-weighted average particle size represented by (vi·di)}/{Σ(vi)} is calculated.

(2) First Water-Soluble Resin The first water-soluble resin is not particularly limited, but polyvinyl alcohol resins, gelatin, celluloses, thickening polysaccharides, and polymers having a reactive functional group can be used. .. Of these, it is preferable to use a polyvinyl alcohol-based resin.

<Polyvinyl alcohol resin>
Examples of the polyvinyl alcohol-based resin include ordinary polyvinyl alcohol (unmodified polyvinyl alcohol) obtained by hydrolyzing polyvinyl acetate, cation-modified polyvinyl alcohol, anion-modified polyvinyl alcohol, nonion-modified polyvinyl alcohol, vinyl alcohol-based polymer and the like. Modified polyvinyl alcohol is mentioned. The modified polyvinyl alcohol may improve the adhesion, water resistance and flexibility of the film.

<gelatin>
As the gelatin, various gelatins that have been widely used in the field of silver halide photographic light-sensitive materials can be applied. For example, acid-processed gelatin, alkali-processed gelatin, enzyme-processed gelatin that is enzymatically processed in the production process of gelatin, a group having an amino group, an imino group, a hydroxy group or a carboxy group as a functional group in a molecule and capable of reacting with it. Examples include gelatin derivatives that have been modified by treatment with a reagent having
When gelatin is used, a hardening agent for gelatin may be added if necessary.

<Cellulose>
As the cellulose, a water-soluble cellulose derivative can be preferably used. For example, water-soluble cellulose derivatives such as carboxymethyl cellulose (cellulose carboxymethyl ether), methyl cellulose, hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose; carboxy group-containing celluloses such as carboxymethyl cellulose (cellulose carboxymethyl ether) and carboxyethyl cellulose; nitro Examples of the cellulose derivative include cellulose, cellulose acetate propionate, cellulose acetate, and cellulose sulfate ester.

<Thickening polysaccharide>
The thickening polysaccharide is a polymer of saccharides and has a large number of hydrogen bonding groups in the molecule. The thickening polysaccharide has a property that a difference in viscosity at low temperature and a difference in viscosity at high temperature are large due to a difference in hydrogen bonding force between molecules depending on temperature. Further, when the metal oxide fine particles are added to the thickening polysaccharide, the viscosity is thought to increase due to hydrogen bonding with the metal oxide fine particles at low temperature. Regarding the range of increase in viscosity, the viscosity at 15° C. is usually 1.0 mPa·s or more, preferably 5.0 mPa·s or more, and more preferably 10.0 mPa·s or more.

The applicable thickening polysaccharide is not particularly limited, and includes generally known natural simple polysaccharides, natural complex polysaccharides, synthetic simple polysaccharides, and synthetic complex polysaccharides. For details of these polysaccharides, refer to "Biochemical Encyclopedia (2nd Edition), Tokyo Kagaku Dojin Shuppan", "Food Industry", Vol. 31, (1988), page 21, and the like.

<Polymer having reactive functional group>
Examples of the polymer having a reactive functional group include polyvinylpyrrolidones, polyacrylic acid, acrylic acid-acrylonitrile copolymer, potassium acrylate-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid- Acrylic resin such as acrylic acid ester copolymer; styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer Polymers, styrene-acrylic acid resins such as styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymers; styrene-sodium styrenesulfonate copolymers, styrene-2-hydroxyethyl acrylate copolymers, styrene-2 -Hydroxyethyl acrylate-potassium styrene sulfonate copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, vinyl acetate -Vinyl acetate-based copolymers such as maleic acid ester copolymers, vinyl acetate-crotonic acid copolymers, vinyl acetate-acrylic acid copolymers; and salts thereof. Of these, it is preferable to use polyvinylpyrrolidones and copolymers containing them.
The above water-soluble resins may be used alone or in combination of two or more.

The weight average molecular weight of the first water-soluble resin is preferably in the range of 1,000 to 200,000, more preferably in the range of 3,000 to 40,000. In addition, in this specification, the value of "weight average molecular weight" shall employ the value measured by gel permeation chromatography (GPC).
The content of the first water-soluble resin is preferably within the range of 5 to 50% by mass, and within the range of 10 to 40% by mass, based on 100% by mass of the solid content of the high refractive index layer. Is more preferable.

(3) Hardener The hardener has a function of reacting with the first water-soluble resin (preferably polyvinyl alcohol resin) contained in the high refractive index layer to form a hydrogen bond network.

The curing agent is not particularly limited as long as it causes a curing reaction with the first water-soluble resin, but generally, a compound having a group capable of reacting with the water-soluble resin or a different group contained in the water-soluble resin Examples thereof include compounds that promote the reaction between them.

As a specific example, when polyvinyl alcohol is used as the first water-soluble resin, boric acid and its salt are preferably used as the curing agent. Further, known curing agents other than boric acid and its salts may be used.

In addition, boric acid and its salt mean the oxyacid and its salt which have a boron atom as a central atom. Specific examples include orthoboric acid, diboric acid, metaboric acid, tetraboric acid, pentaboric acid, octaboric acid, and salts thereof.

The content of the curing agent is preferably 1 to 10% by mass, and more preferably 2 to 6% by mass, based on 100% by mass of the solid content of the high refractive index layer.
In particular, the total amount of the curing agent used when polyvinyl alcohol is used as the first water-soluble binder resin is preferably 1 to 600 mg per 1 g of polyvinyl alcohol, and more preferably 100 to 600 mg per 1 g of polyvinyl alcohol. preferable.

(4) Surfactant The surfactant applicable to the high refractive index layer is not particularly limited, and various conventionally known surfactants can be appropriately selected and used.

(5) Other additives As other additives that can be applied to the high refractive index layer, for example, amino acids, emulsion resins, lithium compounds and the like, JP-A-57-74193, JP-A-57-87988. UV absorbers described in JP-A-62-261476; JP-A-57-74192, JP-A-57-87989, JP-A-60-72785, and JP-A-61-146591. Anti-fading agents described in JP-A No. 1-95091, JP-A No. 3-13376, etc.; JP-A-59-42993, JP-A-59-52689, and JP-A-62-280069. JP-A-61-242871, JP-A-4-219266 and the like; fluorescent whitening agents; sulfuric acid, phosphoric acid, acetic acid, citric acid, sodium hydroxide, potassium hydroxide, potassium carbonate and the like. pH adjusting agent; antifoaming agent; lubricant such as diethylene glycol; antiseptic agent; antifungal agent; antistatic agent; matting agent; heat stabilizer; antioxidant; flame retardant; crystal nucleating agent; inorganic particles; organic particles; reducing agent Various known additives such as viscous agents, lubricants, infrared absorbers, dyes, pigments, etc. may be used as other additives.

(Low refractive index layer)
The low refractive index layer also preferably contains metal oxide particles from the viewpoint of facilitating control of the refractive index. In addition, a water-soluble resin, a curing agent, a surfactant, and other additives may be included as necessary. The metal oxide particles and the water-soluble resin contained in the low refractive index layer are hereinafter referred to as “second metal oxide particles” and “second water-soluble resin”, respectively, for convenience.

(1) Second Water-Soluble Resin As the second water-soluble resin, the same one as the first water-soluble resin can be used.
In this case, when the high refractive index layer and the low refractive index layer both use a polyvinyl alcohol-based resin as the first water-soluble resin and the second water-soluble resin, polyvinyl alcohol-based resins having different saponification degrees are used. It is preferable to use a resin. As a result, the mixing of the interface is suppressed, the infrared reflectance (infrared shielding rate) becomes better, and the haze becomes lower. The “saponification degree” in the present invention means the ratio of hydroxy groups to the total number of acetyloxy groups (derived from vinyl acetate as a raw material) and hydroxy groups in polyvinyl alcohol.

(2) Second Metal Oxide Particles The second metal oxide particles are not particularly limited, but it is preferable to use silica (silicon dioxide) such as synthetic amorphous silica or colloidal silica, and an acidic colloidal silica sol. Is more preferably used. From the viewpoint of further reducing the refractive index, hollow fine particles having pores inside the particles can be used as the second metal oxide particles, and it is particularly preferable to use hollow fine particles of silica (silicon dioxide). ..

The colloidal silica may have its surface cation-modified, or may be treated with Al, Ca, Mg, Ba or the like.
Moreover, the second metal oxide particles may be surface-coated with a surface-coating component.

The average particle diameter (number average; diameter) of the second metal oxide particles (preferably silicon dioxide) contained in the low refractive index layer of the present invention is preferably within the range of 3 to 100 nm. More preferably, it is within the range of 50 nm. The "average particle diameter (number average; diameter)" of the metal oxide fine particles as used in the present invention refers to the particles themselves or particles appearing on the cross section or surface of the refractive index layer observed by an electron microscope, and the number of 1000 The particle size of the particles is measured, and it is determined as a simple average value (number average). Here, the particle size of each particle is represented by the diameter assuming a circle equal to the projected area.

The content of the second metal oxide particles in the low refractive index layer is preferably 0.1 to 85% by mass, and 30 to 80% by mass with respect to 100% by mass of the total solid content of the low refractive index layer. Is more preferable, and it is further preferable that it is 45 to 75 mass %.
From the viewpoint of adjusting the refractive index, the above-mentioned second metal oxide may be used alone or in combination of two or more kinds.

(3) Curing Agent, Surfactant, Other Additives As the curing agent, surfactant, and other additives, those similar to the high refractive index layer can be used, and the description thereof is omitted here.

In the dielectric multilayer film in which the high-refractive index layers and the low-refractive index layers having the above structures are alternately laminated, at least one of the high-refractive index layers and the low-refractive index layers uses a wet film-forming method. It is preferable that the high refractive index layer and the low refractive index layer are both formed by a wet film forming method. Furthermore, it is preferable that at least one of the high refractive index layer and the low refractive index layer contains metal oxide particles. That is, the infrared reflective layer according to the present invention further includes a dielectric multilayer film in which low refractive index layers and high refractive index layers are alternately laminated, and the low refractive index layer or the high refractive index layer is a metal oxide. Configurations that include particles are preferred. Furthermore, it is more preferable that both the high refractive index layer and the low refractive index layer contain metal oxide particles.

In the dielectric multilayer film according to the present invention, it is preferable to design a large difference in refractive index between the low refractive index layer and the high refractive index layer from the viewpoint that the infrared reflectance can be increased with a small number of layers. .. In this embodiment, in at least one of the dielectric multilayer films composed of the low refractive index layer and the high refractive index layer, the refractive index difference between the adjacent low refractive index layer and high refractive index layer is 0.1 or more. Preferably, it is more preferably 0.3 or more. When a plurality of laminates of the high refractive index layer and the low refractive index layer are provided, it is preferable that the difference in the refractive index between the high refractive index layer and the low refractive index layer in all the laminated bodies be within the above-mentioned suitable range. However, even in this case, the refractive index layers constituting the uppermost layer and the lowermost layer of the dielectric multilayer film may have a configuration outside the above-mentioned preferable range.

As the optical characteristics of the kate cover of the present invention, the transmittance in the visible light wavelength region of 380 to 740 nm shown in JIS R3106-1998 is 80% or more, and the average reflectance in the region of wavelength 750 to 1500 nm is 15% or more. It is characterized by being.

From the viewpoint of satisfying the above optical characteristics, the number of refractive index layers of the dielectric multilayer film (total number of high refractive index layers and low refractive index layers) is preferably 6 to 50, and 8 ˜40 layers are more preferred, 11 to 31 layers are still more preferred, and 9 to 30 layers are particularly preferred. When the number of refractive index layers of the dielectric multilayer film is in the above range, excellent heat shielding performance and transparency, suppression of film peeling and cracking, and the like can be realized, which is preferable. When the dielectric multilayer film has a plurality of high refractive index layers and low refractive index layers, each high refractive index layer and each low refractive index layer may be the same or different. Good.

The thickness of each high refractive index layer is preferably in the range of 20 to 800 nm, more preferably in the range of 50 to 500 nm. Further, the thickness of each low refractive index layer is preferably in the range of 20 to 800 nm, and more preferably in the range of 50 to 500 nm.

Here, when measuring the thickness per layer, the composition may change continuously without having a clear interface at the boundary between the high refractive index layer and the low refractive index layer. In the interface region where the composition changes continuously, when the maximum refractive index−the minimum refractive index=Δn, the point of the minimum refractive index+Δn/2 between the two layers is regarded as the layer interface.

When the high refractive index layer and the low refractive index layer contain metal oxide particles, the above composition can be observed from the concentration profile of the metal oxide particles. The metal oxide concentration profile was obtained by performing etching from the surface to the depth direction using a sputtering method, and using an XPS surface analyzer, setting the outermost surface to 0 nm and performing sputtering at a rate of 0.5 nm/min to obtain an atomic composition. It can be seen by measuring the ratio. Alternatively, the laminated film may be cut and the cut surface may be confirmed by measuring the atomic composition ratio with an XPS surface analyzer.

The XPS surface analyzer is not particularly limited, and any model can be used. As the XPS surface analyzer, for example, ESCALAB-200R manufactured by VG Scientific Co., Ltd. can be used. Mg is used for the X-ray anode, and the output is measured at 600 W (accelerating voltage 15 kV, emission current 40 mA).

[4: Other constituent layers]
In the gate cover of the present invention, various functional layers can be appropriately selected and provided in addition to the resin base material, the infrared absorbing layer, and the infrared reflecting layer described above. Hereinafter, the adhesive layer and the hard coat layer will be described as typical functional layers.

[Polarizing layer and polarizing plate]
The gate cover of the present invention can have a polarizing layer (hereinafter, also referred to as a polarizer). By having the polarizing layer, it is preferable that the average transmittance of the linearly polarized light in the visible light wavelength region (380 to 740 nm) of the gate cover of the present invention is 80% or more. Thereby, it is possible to reduce the incident light from the sunlight in the visible light wavelength region into the head-up display without significantly reducing the amount of light emitted from the head-up display.

In the present invention, a polarizing plate film is preferably provided on at least one surface side of the polarizer to form a polarizing plate, and more preferably, the polarizer is provided adjacent to the infrared reflective layer according to the present invention. More preferably, another polarizing plate film is provided on the other surface side of the polarizer.

FIG. 3 is a schematic cross-sectional view showing an example of the configuration of a polarizing plate applicable to the kate cover of the present invention.
In the polarizing plate 21 shown in FIG. 3, a polarizing plate film A (for example, a triacetyl cellulose (TAC) film) represented by 17 is provided with a polarizing layer 14 as a polarizing layer. Adjacent to each other, the infrared reflective layer 13 according to the present invention is provided on the polarizing plate film B (for example, a triacetyl cellulose (TAC) film) represented by 16. The polarizing plate film B represented by 16 functions as a resin base material (also referred to as a support) when forming the infrared reflective layer 13, for example, a dielectric multilayer film. At least one of the polarizing plate films applied to the polarizing plate also has a function as a retardation film.
The polarizing plate 21 included in the gate cover of the present invention is preferably a thin film, and the thickness thereof is preferably in the range of 40 to 100 μm, more preferably in the range of 49 to 99 μm.
Hereinafter, the polarizer and the film for polarizing plate which constitute the polarizing plate will be described in this order.

(Polarizer)
A polarizer is an element that allows only light having a plane of polarization in a certain direction to pass therethrough, and a typical polarizer known at present is a polyvinyl alcohol-based polarizing film. The polyvinyl alcohol-based polarizing film includes a polyvinyl alcohol-based film dyed with iodine and a polyvinyl alcohol-based film dyed with a dichroic dye.

The polyvinyl alcohol-based polarizing film may be a film obtained by uniaxially stretching a polyvinyl alcohol-based film and then dyeing it with iodine or a dichroic dye (preferably a film further subjected to durability treatment with a boron compound); A film obtained by dying an alcohol-based film with iodine or a dichroic dye and then uniaxially stretching (preferably a film further subjected to a durability treatment with a boron compound) may be used. The absorption axis of the polarizer is usually parallel to the maximum stretching direction.

For example, as described in JP-A-2003-248123 and JP-A-2003-342322, the ethylene unit content is in the range of 1 to 4 mol %, the polymerization degree is in the range of 2000 to 4000, and the saponification degree is 99.0. Ethylene-modified polyvinyl alcohol in the range of ˜99.99 mol% is used. Above all, an ethylene-modified polyvinyl alcohol film having a hot water cutting temperature in the range of 66 to 73° C. is preferably used.
The thickness of the polarizer is preferably in the range of 5 to 30 μm, and more preferably in the range of 5 to 25 μm in order to make the polarizing plate thin.

(Polarizing film)
As the polarizing plate film applied to the production of the polarizing plate, the same resin base material as described in the above “1: Resin base material” can be appropriately selected and applied.
In the gate cover of the present invention, also with respect to the polarizing plate film constituting the polarizing plate, the in-plane retardation value R _O is 0 nm or more from the viewpoint of obtaining excellent visibility, as in the resin substrate 11 described above. , 100 nm is the most preferable form.

Examples of the resin material constituting the polarizing plate film applicable to the polarizing plate according to the present invention include polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (abbreviation: TAC), cellulose acetate butyrate, cellulose acetate Pionate (abbreviation: CAP), cellulose acetate phthalate, cellulose nitrate and other cellulose esters and their derivatives, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate (abbreviation: PC), norbornene resin , Polymethylpentene, polyetherketone, polyimide, polyethersulfone (abbreviation: PES), polyphenylene sulfide, polysulfones, polyetherimide, polyetherketone imide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic and polyarylate And cycloolefin resins such as Arton (trade name, manufactured by JSR) and Apel (trade name, manufactured by Mitsui Chemicals, Inc.). Among these resin base materials, a resin base material having a resin component of triacetyl cellulose (TAC), cycloolefin resin, polycarbonate (PC) resin, acrylic resin and polyarylates is preferably used.

The thickness of the polarizing plate film is not particularly limited, but is preferably within the range of 10 to 100 μm, more preferably within the range of 10 to 60 μm, and further preferably within the range of 20 to 60 μm. Particularly preferred.

(Method for producing polarizing plate)
As a method of manufacturing the polarizing plate according to the present invention, for example, in the case of the polarizing plate 21 shown in FIG. 3, basically, as described above, the polarizing plate film A represented by 17 is used as a polarizing film. It can be attached to one side. However, it is preferable to subject the surface of the polarizing plate film A represented by 17 to the polarizer 14 side to an easy adhesion treatment (surface activation treatment).

The polarizing plate 21 can be manufactured by a method including the following steps (1 to 5).
Step 1: A polyvinyl alcohol film is uniaxially stretched. This is immersed in an aqueous solution containing iodine and potassium iodide, and then immersed in an aqueous solution containing potassium iodide and boric acid. Then, this is washed with water and dried to obtain a polarizer.

Step 2: The polarizer 14 obtained in the above step 1 is placed on the surface of the polarizing plate film A (for example, TAC) represented by 17 whose surface has been subjected to easy adhesion treatment in advance.

Step 3: A polyvinyl alcohol adhesive (completely saponified polyvinyl alcohol aqueous solution) is applied to the opposite surface of the polarizer 14 placed on the polarizing plate film A represented by 17 above.

Step 4: Separately, a low refractive index layer and a high refractive index layer are alternately laminated on a polarizing plate film B (for example, TAC) represented by 16 according to a conventional method to form a dielectric multilayer film. The infrared reflection layer 13 is formed.

Step 5: The infrared reflection layer 13 produced in Step 4 is placed on the surface of the polarizer coated with the polyvinyl alcohol adhesive obtained in Step 3 so as to face the polarizer 14 to form a laminate. ..

Step 6: A pressure is applied to the laminate obtained in Step 5 to bond them together.

Step 7: The laminated body obtained in Step 6 is dried to prepare the polarizing plate 21.

In the above step 2, when the polarizing plate film A represented by 17 is attached to the polarizer 14, for example, a commercially available cellulose acylate-based protective film (for example, Konica Minolta Tack KC8UX, KC5UX, KC8UCR3, KC8UCR4, (Konica Minolta Co., Ltd.) is also preferably used. When such a protective film is applied as a polarizing plate film, it is necessary to perform surface activation treatment such as saponification treatment in advance.

Examples of the easy adhesion treatment include corona (discharge) treatment, plasma treatment, flame treatment, itro treatment, glow treatment, ozone treatment, primer coating treatment, and the like, and at least one of them may be performed. Among these easy adhesion treatments, from the viewpoint of productivity, corona treatment and plasma treatment are preferable as the easy adhesion treatment.

As the adhesive, a water-based adhesive containing a polyvinyl alcohol-based resin or a urethane resin as a main component, or an active energy ray-curable adhesive containing a photo-curable resin such as an epoxy resin as a main component can be used. .. For example, an adhesive containing an acrylic polymer, a silicone polymer, polyester, polyurethane, polyether or the like as a base polymer may be used.

[Adhesive layer]
The gate cover of the present invention may further have an adhesive layer. With this adhesive layer, the infrared absorbing layer unit B represented by U2 and the infrared absorbing layer unit A represented by U3 can be adhered to both sides of the polarizing plate unit U1 described later. A known release paper (separator) may be provided on the adhesive layer. Further, the function of the infrared absorbing layer can be imparted by including the infrared absorbing agent in the adhesive layer containing the adhesive.

The constitution of the pressure-sensitive adhesive layer is not particularly limited, and for example, any of dry laminating agent, wet laminating agent, pressure-sensitive adhesive, heat seal agent, hot melt agent and the like can be used. As the adhesive, for example, polyester resin, urethane resin, polyvinyl acetate resin, acrylic resin, nitrile rubber or the like is used. Further, it may be a layer having an adhesive property obtained by removing the near infrared absorbing organic compound or the metal oxide infrared absorbing agent from the infrared absorbing layer described above.

The thickness of the adhesive layer is preferably in the range of 1 to 100 μm, more preferably in the range of 3 to 50 μm. When the layer thickness is 1 μm or more, the tackiness tends to be improved and sufficient tackiness can be obtained. On the contrary, when it is 100 μm or less, the transparency of the gate cover is improved, which is preferable.

As another method of forming the adhesive layer, for example, after coating the adhesive layer coating liquid on the release paper (separator) on the protective film 19 and drying to bond the adhesive layer, peel the release paper, A method of attaching the plates 21 can also be mentioned.

〔Protective film〕
As the protective film provided on the front surface side of the gate cover, the same resin base material as described in “1: Resin base material” can be appropriately selected and applied.
That is, in the gate cover of the present invention, the in-plane retardation value R _O is also 0 nm or more and less than 100 nm from the viewpoint of obtaining excellent visibility in the protective film as in the case of the resin base material 11 described above. Is the most preferred form.

Examples of the resin material of the protective film constituting the gate cover of the present invention include polyethylene, polypropylene, cellophane, cellulose diacetate, cellulose triacetate (abbreviation: TAC), cellulose acetate butyrate, cellulose acetate propionate (abbreviation: CAP). ), cellulose acetate phthalate, cellulose esters such as cellulose nitrate and their derivatives, polyvinylidene chloride, polyvinyl alcohol, polyethylene vinyl alcohol, syndiotactic polystyrene, polycarbonate (abbreviation: PC), norbornene resin, polymethylpentene, poly Ether ketone, polyimide, polyether sulfone (abbreviation: PES), polyphenylene sulfide, polysulfones, polyetherimide, polyetherketone imide, polyamide, fluororesin, nylon, polymethylmethacrylate, acrylic and polyarylate, Arton (trade name) , Manufactured by JSR) and Apel (trade name, manufactured by Mitsui Chemicals, Inc.) and the like. Among these resin base materials, a resin base material having a resin component of triacetyl cellulose (TAC), cycloolefin resin, polycarbonate (PC) resin, acrylic resin and polyarylates is preferably used.

[Hard coat layer]
In the gate cover of the present invention, as a surface protective layer for enhancing scratch resistance, a hard coat layer (HC layer) containing a resin curable by heat, ultraviolet rays or the like is formed on the uppermost layer opposite to the surface having the resin base material. ) May be laminated.

Examples of the curable resin used in the hard coat layer include a thermosetting resin and an ultraviolet curable resin, but an ultraviolet curable resin is preferable from the viewpoint of easy coating film formation, and among them, a pencil hardness of at least 2H. Are more preferred. The curable resins may be used alone or in combination of two or more.

Examples of such an ultraviolet curable resin include (meth)acrylate, urethane acrylate, polyester acrylate, epoxy acrylate, epoxy resin, and oxetane resin, which can also be used as a solventless resin composition.

When the above ultraviolet curable resin is used, it is preferable to add a photopolymerization initiator to accelerate curing.
As the photopolymerization initiator, acetophenones, benzophenones, ketals, anthraquinones, thioxanthones, azo compounds, peroxides, 2,3-dialkyldione compounds, disulfide compounds, thiuram compounds, fluoroamine compounds Etc. are used.

The thickness of the hard coat layer is preferably 0.1 to 50 μm, and more preferably 1 to 20 μm from the viewpoint of improving the hard coat property and improving the transparency of the gate cover.
The method for forming the hard coat layer is not particularly limited, for example, after preparing a hard coat layer coating liquid containing the above components, the coating liquid is applied by a wet coating method, for example, a wire bar or the like, and heat energy or Examples include a method of curing the formed hard coat layer coating film by irradiation with active energy rays to form a hard coat layer.

[Other functional layers]
The gate cover of the present invention may have other functional layers in addition to the layers described above. For example, an intermediate layer can be provided as the other functional layer. Here, the "intermediate layer" means a layer between the resin base material and the infrared absorbing layer, or a layer between the infrared reflecting layer and the infrared absorbing layer.

Examples of the constituent material of the intermediate layer include a polyester resin, a polyvinyl alcohol resin, a polyvinyl acetate resin, a polyvinyl acetal resin, an acrylic resin, and a urethane resin, and a material having a low additive compatibility and a low Tg is preferably used.

[Spectral characteristics of gate cover]
In the gate cover of the present invention, the average transmittance in the visible light wavelength region of 380 to 740 nm is 80% or more, preferably 80% or more and 95% or less. Further, the average reflectance in the near infrared wavelength region of 750 to 1500 nm is 15% or more, preferably 15% or more and 50% or less, and more preferably 20% or more and 45% or less. is there.
Furthermore, in the gate cover of the present invention, it is preferable that the average transmittance of linearly polarized light in the visible light wavelength region of 380 to 740 nm is 80% or more.

The average transmittance in the visible light wavelength region of 380 to 740 nm and the average transmittance of linearly polarized light in the visible light wavelength region of 380 to 740 nm are measured using a spectrophotometer V-570 (manufactured by JASCO Corporation) at wavelengths of 380 to 380. The average transmittance can be obtained by measuring the range of 740 nm every 2 nm. When measuring the average transmittance of linearly polarized light, the linearly polarized light is incident on the gate cover so that the plane of polarization is parallel to the transmission axis of the polarizer of the gate cover, and the average transmittance is obtained.

Moreover, the average reflectance in the near infrared wavelength region of 750 to 1500 nm is the reflectance (DS) of the manufactured gate cover by using a spectrophotometer (U-4000 manufactured by Hitachi High-Technologies Corporation) according to JIS K 5602:2008. Based on (How to obtain the solar radiation reflectance of the coating film), the average reflectance is obtained by measuring the wavelength range of 750 to 1500 nm at intervals of 2 nm.

<<Typical configuration and manufacturing example of gate cover>>
A specific configuration example of the gate cover including the above-described elements will be described with reference to the drawings.

(Embodiment 1: Configuration example 1)
FIG. 4 is a schematic cross-sectional view (Embodiment 1) showing a first configuration example of the head-up display gate cover, in which the light source of the liquid crystal display device is arranged on the lower surface side of the drawing.

The gate cover 3 shown in FIG. 4 includes a polarizing plate film B (for example, a infrared ray absorbing layer B/16 represented by a resin substrate 11 (for example, a polycarbonate film (PC))/12 from the lower surface side (for example, TAC)/infrared reflecting layer 13/polarizing layer 14/17 film for polarizing plate A (eg TAC)/18 infrared absorbing layer A represented by 18/protective film 19 (eg PC)/hard coat layer It is composed of 20.

In the gate cover 3 of the present invention having the configuration shown in FIG. 4, the in-plane retardation value R _O of the resin base material 11 is characterized by being 0 nm or more and less than 100 nm, and further represented by 16. All of the polarizing plate film A and the protective film 19 represented by the polarizing plate films B and 17 have an in-plane retardation value R _O defined by the resin substrate 11 of 0 nm or more and less than 100 nm. , The most preferred form.

The method of manufacturing the gate cover 3 having the configuration shown in FIG. 4 is as follows.
<Step 1: Fabrication of polarizing plate unit>
A polarizing plate unit (U1) is produced according to steps 1 to 7 described in the method for producing a polarizing plate.

<Step 2: Preparation of infrared absorbing layer unit B>
An infrared absorbing layer B represented by 12 containing an adhesive resin is formed on the resin substrate 15 to prepare an infrared absorbing layer unit B represented by infrared U2.

<Step 3: Preparation of infrared absorbing layer unit A>
An infrared absorbing layer A represented by 18 containing an adhesive resin is formed on the protective film.

<Step 4: Bonding of Polarizing Plate Unit and Infrared Absorption Layer Unit A>
First, a position where the polarizing plate film A surface represented by 17 of the polarizing plate unit U1 and the infrared absorbing layer A surface represented by 18 including the adhesive resin of the infrared absorbing layer unit A represented by U3 face each other. Place it on and stick it with a bonding roller.

<Step 5: Bonding of Polarizing Plate Unit and Infrared Absorption Layer Unit B>
Next, the infrared absorbing layer B surface represented by 12 of the infrared absorbing layer unit B represented by U2 and the polarizing plate film B surface represented by 16 of the polarizing plate unit U1 are arranged at positions facing each other, Laminate with a laminating roller.

<Step 6: Formation of hard coat layer>
Finally, the hard coat layer 20 is formed on the protective film 19, and the gate cover 3 is produced.

(Embodiment 2: Configuration example 2)
FIG. 5 is a schematic cross-sectional view (Embodiment 2) showing a second configuration example of the head-up display gate cover, in which the light source of the liquid crystal display device is arranged on the lower surface side of the drawing.

The gate cover 3 shown in FIG. 5 is for a polarizing plate represented by a resin substrate 11 (for example, a polycarbonate film (PC))/12 infrared absorption layer B/infrared reflection layer 13/16 from the lower surface side. Film B (for example, TAC)/polarizing film 14/17 for polarizing plate A (for example, TAC)/infrared absorption layer A represented by 18/protective film 19 (for example, PC)/hard coat layer It is configured in the order of 20.

Also in the gate cover 3 of the present invention configured as shown in FIG. 5, the in-plane retardation value R _{O of} the resin base material 11 is characterized by being 0 nm or more and less than 100 nm, and further represented by 16. All of the polarizing plate film A and the protective film 19 represented by the polarizing plate films B and 17 have an in-plane retardation value R _O defined by the resin substrate 11 of 0 nm or more and less than 100 nm. , The most preferred form.

The method of manufacturing the gate cover 3 having the structure shown in FIG. 5 is different from the above-described structure example 1 shown in FIG. 4 in the arrangement order of some constituent layers, but can be manufactured by the same method.

《Liquid crystal display device》
A liquid crystal display device will be described as an example of a preferable display device used for the head-up display according to the present invention.

FIG. 6 is a schematic diagram showing an example of the basic configuration of the liquid crystal display device 30. As shown in FIG. 6, the liquid crystal display device 30 basically includes a liquid crystal cell 32, a first polarizing plate 31 and a second polarizing plate 33 that sandwich the liquid crystal cell 32, and a backlight 34. Composed.

The display mode of the liquid crystal cell 32 is not particularly limited, and may be, for example, TN (Twisted Nematic), VA (Vital Alignment), IPS (In Plane Switching), or the like. A liquid crystal cell for mobile devices is preferably, for example, an IPS mode liquid crystal cell, and a medium or large-sized liquid crystal cell is preferably for example, a VA mode liquid crystal cell.

The first polarizing plate 31 is arranged on the surface of the liquid crystal cell 32 on the viewing side, and is arranged on the surface of the first polarizer 31a opposite to the liquid crystal cell 32 of the first polarizer 31a. It includes a first protective film 31b and a second protective film 31c arranged on the surface of the first polarizer 31a on the liquid crystal cell 32 side.

The second polarizing plate 33 is arranged on the surface of the liquid crystal cell 32 on the backlight 34 side, and is arranged on the surface of the second polarizer 33a and the second polarizer 33a on the liquid crystal cell side. The protective film 33b and the protective film 33c arranged on the surface of the second polarizer 33a opposite to the liquid crystal cell are included. The absorption axis of the second polarizer 33a is preferably orthogonal to the absorption axis of the first polarizer 31a.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto. In the examples, "%" is used, but "% by mass" is used unless otherwise specified.
<<Fabrication of gate cover>>
[Production of gate cover 1]
The gate cover 1 having the structure shown in FIG. 4 was manufactured according to the following method.

(Production of infrared reflective layer unit)
(1) Preparation of coating liquid 1 for forming a low refractive index layer A methyldiallylamine hydrochloride polymer (including a tertiary amine salt) as a cationic polymer in a stirring container (PAS-M-1, weight average molecular weight 20000, 50% by mass). Aqueous solution, Nitto Bo Medical Co., Ltd.) 4.0 g, diallyldimethylammonium chloride polymer (including quaternary ammonium group) (PAS-H-5L, weight average molecular weight 30,000, 28 mass% aqueous solution, Nitbo Bo Medical Co., Ltd.) 5.0 g, rinse water 31 g, and boric acid (3 mass% aqueous solution) 31.9 g were mixed. To this, 489.9 g of an aqueous solution of 10 mass% acidic colloidal silica (ST-OXS, concentration 10%, average primary particle size: 4 to 6 nm, manufactured by Nissan Chemical Industries, Ltd.) was added. This was heated to 40° C. with stirring. Here, an 8% by mass aqueous solution of polyvinyl alcohol (JP-45, degree of polymerization 4500, degree of saponification 88 mol%, manufactured by Nihon Bibi Poval Co., Ltd.) as a hydrophilic polymer (binder) was used as a binder ratio in the reflective layer of 70. 30.5 g of emulsion resin (Superflex 650, Daiichi Kogyo Seiyaku Co., Ltd.) and 5% by mass of a surfactant solution (Softofazoline LMEB-R, Kawaken Fine Chemicals Co., Ltd.). A mixed liquid of 6.3 g and pure water 15 g was added, and the mixture was stirred and mixed at 40° C. to obtain a coating liquid 1 for forming a low refractive index layer.
The refractive index at a light wavelength of 589.3 nm of the single layer prepared using the coating liquid 1 for forming a low refractive index layer was 1.50 as a result of measurement by a conventional method.

(2) Preparation of coating liquid 1 for forming high refractive index layer Dispersion liquid of 30 mass% zirconium oxide particles (SZR-W, zirconia sol, particle size distribution: D50 3-5 nm, manufactured by Sakai Chemical Industry Co., Ltd.) 384.8 g 175.4 g of an aqueous citric acid solution (1.9% by mass) was added. 1.94 g of a 5 mass% aqueous solution of a surfactant (Softofazoline LMEB-R, manufactured by Kawaken Fine Chemical Co., Ltd.) was added to this, and this was heated to 40°C. Next, 120.4 g of an 8 mass% aqueous solution of ethylene-modified polyvinyl alcohol (Kuraray Co., Ltd., Exceal RS2117, saponification degree: 97.5 to 99 mol%) was added, and further 9.9 g of pure water was added. After stirring this for 10 minutes, a 6 mass% aqueous solution of polyvinyl alcohol (JC-40, saponification degree: 99 mol% or more, manufactured by Nihon Bibi Povar Co., Ltd.) as a hydrophilic polymer was used as a binder ratio in the reflective layer of 70 mass. % So that 66.7 g of pure water was further added. Then, it stirred at 40 degreeC for 180 minutes, and obtained the coating liquid 1 for high refractive index layer formation.
The refractive index of the single layer produced using the coating liquid 1 for forming a high refractive index layer was 1.73.

(3) Formation of infrared reflective layer Using a slide hopper type coating apparatus capable of simultaneous coating of 22 layers, the coating liquid 1 for forming a low refractive index layer and the coating liquid 1 for forming a high refractive index layer prepared above were heated to 45°C. As a polarizing plate film B represented by 16, while keeping warm, a triacetyl cellulose (TAC) film (TAC film manufactured by Konica Minolta Co., Ltd.) saponified by immersing in a 1 mol/L NaOH aqueous solution for 1 minute. KC6UA) was subjected to simultaneous 21-layer multilayer coating (a total of 21 layers of low refractive index layers and high refractive index layers were alternately laminated). At this time, the lowermost layer (resin base material side) and the uppermost layer are low refractive index layers (thickness after drying: 85 nm), and other than that, the low refractive index layer (thickness after drying: 92 nm) and high refractive index. Infrared reflective layer I (in Table I, R1 and R1 in Table I) composed of 21 layers on polarizing plate film B represented by 16 such that layers (thickness after drying: 79 nm) were alternately laminated. Abbreviated) was prepared.
The average reflectance (%) at 750 to 1500 nm of the infrared reflective layer I produced above was 18% as a result of measurement by the following method.

<Measurement of average reflectance (%) at 750 to 1500 nm>
As a spectrophotometer, U-4100 manufactured by Hitachi High-Technologies Corporation was used for measurement. Regarding the infrared reflective layer unit, the reflectance (DS) was measured in the range of wavelength 750 to 1500 nm at intervals of 2 nm according to JIS K 5602:2008 (method of determining solar reflectance of coating film), and the average thereof was obtained. The reflectance was calculated.

(Production of polarizing plate unit)
A polarizer and a polarizing plate unit U1 were produced by the following steps Step 1: The polyvinyl alcohol film was uniaxially stretched (temperature 110° C., stretching ratio 5 times). This was immersed in an aqueous solution containing 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and then immersed in an aqueous solution of 6 g of potassium iodide, 7.5 g of boric acid and 100 g of water at 68°C. This was washed with water and dried to finally obtain a polarizer 14 having a thickness of 5 μm.
As a polarizing plate film A represented by step 2:17, on the surface of a triacetyl cellulose (TAC) film (TAC film manufactured by Konica Minolta Co., Ltd., KC6UA) which has been subjected to corona discharge treatment on the surface in advance, the above step 1 The obtained polarizer 14 was mounted. The conditions for the corona discharge treatment were a corona output intensity of 2.0 kW and a line speed of 18 m/min.
Step 3: A polyvinyl alcohol adhesive having a solid content of 2% by mass (completely saponified polyvinyl alcohol aqueous solution) is thickly formed on the opposite surface of the polarizer 14 placed on the polarizing plate film A represented by 17 above. 2 μm in thickness.
Step 4: On the surface of the polarizer coated with the polyvinyl alcohol adhesive obtained in Step 3, the infrared reflective layer 13 surface of the infrared reflective layer unit prepared above and the adhesive layer surface of the polarizer 14 are bonded together. A polarizing plate 21 having the configuration shown in FIGS. 3 and 4 which is the polarizing plate unit U1 was produced.

(Preparation of infrared absorbing layer unit B)
As an acrylic adhesive, SK Dyne 2094 (manufactured by Soken Chemical Industry Co., Ltd.) was mixed with ITO dispersion liquid (T-1 dispersion medium: methyl isobutyl ketone manufactured by Mitsubishi Materials Electronics Co., Ltd.) for the total amount of SK Dyne 2094 resin. The dispersion liquid was added so that the solid content was 40% by mass to prepare an infrared absorbing layer forming coating liquid b1.
Next, as the resin substrate 11, a polycarbonate film F1 (PURE-ACE C110, manufactured by Teijin Ltd., thickness 100 μm) was used, and the coating liquid for forming an infrared absorbing layer was prepared by the wet coating method so as to have a dry film thickness of 10 μm. After applying b1, it was dried at 80° C. for 1 minute to prepare an infrared absorbing layer unit B represented by U2 having an infrared (IR) absorbing layer B represented by 12 on the resin substrate 11. ..

(Laminating the polarizing plate unit and infrared absorbing layer unit B)
Next, the polarizing plate film B surface represented by 16 constituting the above-prepared polarizing plate unit (U1, polarizing plate 21), and the infrared absorbing layer 12 surface of the infrared absorbing layer unit B represented by U2 prepared above. Were opposed to each other, and pressure was applied by a bonding roller to bond them.

(Preparation of infrared absorbing layer unit A)
As an infrared absorbing layer forming coating solution for forming the infrared absorbing layer unit B represented by U2, instead of the infrared absorbing layer forming coating solution b1, an infrared absorbing layer forming coating solution a1 prepared by the following method is used. An infrared absorbing layer unit A represented by U3 was produced in the same manner except that it was used.

(Preparation of coating liquid a1 for forming infrared absorbing layer)
As an acrylic pressure-sensitive adhesive, SK Dyne 2094 (manufactured by Soken Chemical Industry Co., Ltd.) was used as a near-infrared absorbing organic compound having a maximum absorption peak in the near-infrared wavelength region of 750 to 1200 nm, and YKR-2090 (λmax manufactured by Yamamoto Kasei Co., Ltd.). :830 nm Dye 1) is dissolved in methyl isobutyl ketone to prepare a dye solution, and the solid content of Dye 1 is added to the total resin amount of SK Dyne 2094 to be 14% by mass, and infrared rays are added. A coating liquid a1 for forming an absorption layer was prepared.

Next, as a protective film 19, a polycarbonate film F1 (manufactured by Teijin Ltd., PURE-ACE C110, thickness 100 μm) was used, and the adhesive layer-forming coating liquid 1 prepared above by a wet coating method so as to have a dry film thickness of 10 μm. After coating, it was dried at 80° C. for 1 minute to prepare an infrared absorbing layer unit A represented by U3 having an infrared absorbing layer A represented by 18 on the protective film 19.

(Lamination of Polarizing Plate Unit/Infrared Absorption Layer Unit B and Infrared Absorption Layer Unit A)
Then, the polarizing plate film A surface represented by 17 and the infrared absorption layer represented by U3, which are obtained by laminating the above-prepared polarizing plate units U1 and U2 represented by the infrared absorption layer unit B. The infrared absorption layer A surface represented by 18 of the unit A was made to face and pressure was applied by a bonding roller to bond.

(Formation of hard coat layer 20)
Finally, OPSTAR KZ6445A (manufactured by Arakawa Chemical Co., Ltd., silica hybrid UV curable material) was applied onto the protective film 19 of the above-prepared laminate so that the dry film thickness was 3 μm, and a UV curing device (manufactured by FUSION) ), the composition was cured under the conditions of an output of 70% and a conveying speed of 20 m to form an HC layer, and a gate cover 1 having the configuration shown in FIG. 4 was produced.

[Production of gate cover 2]
In the production of the gate cover 1, the concentration (mass %) of the metal oxide infrared absorbing agent and the near infrared absorbing organic compound contained in the infrared (IR) absorbing layer B was changed as shown in Table I to obtain the gate cover. A gate cover 2 was produced in the same manner as 1.

[Production of gate cover 3]
A gate cover 2 was prepared in the same manner as in the preparation of the gate cover 2 except that an infrared reflective layer II (R2) formed by the following method was used instead of the infrared reflective layer I (R1).

(Formation of infrared reflective layer II)
In the preparation of the infrared reflective layer unit 1, the same low-refractive index layer-forming coating solution 1 and high-refractive index layer-forming coating solution 1 as those used in the preparation of the gate cover 2 were used, and after drying as shown below. The coating conditions were changed so as to obtain a thickness, and 21 layers were simultaneously coated in layers to form an infrared reflective layer II (R2).
At this time, the lowermost layer (resin substrate side) and the uppermost layer have a low-refractive index layer having a thickness of 108 nm after drying, and the other low-refractive index layers have a thickness after drying of 117 nm and a high-refractive index layer. The subsequent thickness was set to 101 nm, and the infrared reflective layer II (R2) composed of 21 layers was formed on the polarizing plate film B represented by 16 such that they were alternately laminated. The average reflectance (%) at 750 to 1500 nm of the infrared reflective layer II was 23% as a result of measuring by the above method.

[Fabrication of Gate Covers 4, 5, 9-12 and 15-20]
In the production of the gate cover 3, the type and concentration (mass %) of the metal oxide infrared absorbing agent and the near infrared absorbing organic compound contained in the infrared absorbing layer are changed so as to be in Table I, and the gate cover 3 Gate covers 4, 5, 9 to 12 and 15 to 20 were produced in the same manner as in.
However, in the manufacture of the gate cover 11, the layer structure of the gate cover was changed from the structure shown in FIG. 4 to the structure in which the infrared absorption layer B and the infrared reflection layer 13 shown by 12 shown in FIG. 5 were adjacent to each other.
Further, in the production of the gate covers 17 to 20, the configuration (referred to as FIG. 4, modified 1) in which the polarizer was removed from the configuration of the polarizing plate unit in the production of the gate cover 1 was changed.

[Production of gate covers 6 to 8]
In the production of the gate cover 5, the gate cover 6 to the same as the gate cover 6 except that the addition layer of the CWO dispersion used for the infrared absorbing layer B was contained in the hard coat (HC) layer at the concentration shown in Table I. 8 was produced. The HC layer also has the function of an infrared absorption layer.

[Production of gate cover 13]
In the production of the above-mentioned gate cover 12, the infrared reflection layer III (R3) formed by the following method was used in place of the infrared reflection layer II (R2) used in the production of the infrared reflection layer unit 1 in the same manner. The gate cover 13 was produced.

(Formation of infrared reflective layer III)
On the TAC film, which is the polarizing plate film B represented by 16, according to the method for forming the heat shield film JQ2 described in the example of JP-A-2017-122025, the ITO ( Film thickness: 37 nm)/Ag (film thickness: 4 nm)/ITO (film thickness: 60 nm)/Ag (film thickness: 4 nm)/ITO (film thickness: 68 nm)/Ag (film thickness: 4 nm)/ITO (film thickness : 34 nm), and the infrared reflective layer III (R3) was formed by sequentially laminating a metal film having a constitution.

[Production of gate cover 14]
In the production of the gate cover 12, the near infrared absorbing organic compound and the infrared absorbing layer B are changed by changing the addition layer of the ITO dispersion liquid which is a metal oxide infrared absorbing agent from the infrared absorbing layer B to the infrared absorbing layer A. A gate cover 14 was produced in the same manner except that the contained infrared reflective layer A was used.

[Production of gate cover 21]
In the production of the gate cover 3, the resin base material 11 is changed from the polycarbonate film F1 (in-plane retardation value Ro: 32 nm) to the polycarbonate film F2 (manufactured by Teijin Limited, PURE-ACE RM, thickness 70 μm, in-plane retardation). The value of Ro: 125 nm) was changed, and the concentration (mass%) of ITO and dye 1 contained in the infrared absorption layer was changed as shown in Table I, and the gate cover 21 was prepared in the same manner.

[Production of gate cover 22]
The gate cover 21 is manufactured in the same manner except that the resin base material is changed from the polycarbonate film F2 to the polycarbonate film F1 and the infrared reflective layer is removed (referred to as FIG. 4, modified 2) in the production of the gate cover 21. 22 was produced.

[Production of gate covers 23 to 25]
A gate cover 23 was produced in the same manner as in the production of the gate cover 1 except that the dye 1 in the infrared absorbing layer A was removed. A gate cover 24 was produced in the same manner as in the production of the gate cover 1 except that the ITO in the infrared absorption layer B was removed. Further, a gate cover 25 was produced in the same manner as in the production of the gate cover 1 except that the dye 1 in the infrared absorbing layer A and the ITO in the infrared absorbing layer B were removed.

[Production of gate cover 26]
In the production of the gate cover 11, the resin base material 11 was changed to a PET film (manufactured by Teijin DuPont Films, thickness: 100 μm), and the concentration of the near infrared absorbing organic compound was changed as shown in Table I, Further, the gate cover 26 was produced in the same manner except that the infrared reflective layer R2 was replaced with a PET/PET laminated body having the following structure.
The PET film used as the resin substrate is shown as F3 in Table I.

(PET/PET laminate)
“NANO90S”, which is a PET laminated thermal barrier film manufactured by Sumitomo 3M, was used. NANO90S is a PET film laminate having a film thickness of 50 μm and a PET laminate number of 200 layers.

The infrared absorbers used for producing the gate cover are shown below.
Metal oxide infrared absorber (infrared absorber-1)
ITO: ITO dispersion liquid (Mitsubishi Materials Denshi Kasei Co., Ltd. T-1 dispersion medium: methyl isobutyl ketone)
CWO: CWO dispersion (YMF-02A manufactured by Sumitomo Metal Mining Co., Ltd.)
ATO: ATO dispersion (CP5C manufactured by Keeling & Walker)
AZO: AZO dispersion (manufactured by Mitsui Kinzoku Co., Ltd.)

Near infrared absorbing organic compound (infrared absorber-2)
Dye 1: YKR-2090 manufactured by Yamamoto Kasei (λmax: 830 nm)
Dye 2: Infrared absorbing dye 2 having the following structure (Spectrum Info: λmax: 995 nm)

Dye 3: YKR-2900 manufactured by Yamamoto Kasei (λmax: 897 nm)
Dye 4: YKR-2200 manufactured by Yamamoto Kasei (λmax: 1007 nm)
Dye 5: Dye 5 having a maximum absorption peak in the near infrared wavelength region of 750 to 1200 nm was prepared and used as follows.

(Preparation of Dye 5)
Dye 5 was prepared by the method described in paragraphs (0112) to (0113) of JP-A-2011-099038. Specifically, first, a solution (a) prepared by dissolving 0.149 g (7.46×10 ⁻⁴ mol) of copper acetate monohydrate in 25 g of dimethylformamide (DMF), and copper acetate monohydrate. On the other hand, an equimolar amount of ethylphosphonic acid (0.0821 g) and 0.13 g (1.67×10 ⁻⁴ mol) of DDP-6 (manufactured by Nikko Chemicals Co., Ltd.), which is a phosphoric acid ester compound, were dissolved in 25 g of DMF. Solutions (b) were prepared respectively.

Then, the solution (a) and the solution (b) obtained above were mixed and reacted at room temperature for 2 hours with stirring. After the reaction, the by-products and the solvent were distilled off from the obtained reaction mixture at 60° C. under reduced pressure. Then, 5 g of toluene was added to this solution and ultrasonic wave irradiation was carried out to carry out redispersion treatment to obtain dye 5 which is an infrared absorber.
Table I shows the configuration of each of the gate covers produced above.

<<Measurement of gate cover characteristic values>>
[Measurement of in-plane retardation Ro value]
With respect to the resin base material used for the production of each gate cover, the in-plane retardation value Ro at an incident angle of 0° and a measurement wavelength of 550 nm was measured at 23° C. and 55% RH using an automatic birefringence meter Axoscan. It was measured under the environment.

[Measurement of average transmittance at 380 to 740 nm]
The average transmittance in the visible light wavelength region of 380 to 740 nm was measured for each of the above prepared head covers using a spectrophotometer (V-570, manufactured by JASCO Corporation).

[Measurement of average transmittance of linearly polarized light at 380 to 740 nm]
For each of the head covers prepared above, a spectrophotometer (V-570, manufactured by JASCO Corporation) was used, and a polarizing plate was placed on the halogen light source to make linearly polarized light, and the polarization direction of the light source was made parallel to the transmission axis direction of the gate cover. The average transmittance of linearly polarized light in the visible light wavelength region of 380 to 740 nm was measured.

[Measurement of average reflectance at 750 to 1500 nm]
As a spectrophotometer, U-4100 manufactured by Hitachi High-Technologies Corporation was used for measurement. Regarding the infrared reflective layer unit, the solar reflectance (DS) was measured in accordance with JIS K 5602:2008 (how to determine the solar reflectance of the coating film) in the wavelength range of 750 to 1500 nm every 2 nm, and The average reflectance was calculated.

<<Evaluation of head-up display>>
[Evaluation of heat shielding property]
(Preparation of HUD device for evaluation)
To the head-up display (24 inches) mounted on the Toyota Lexus LS, remove the existing gate cover provided and attach the above-mentioned gate covers (position 3 in FIG. 1) to the above. HUD devices 1 to 26 for evaluation equipped with the respective manufactured gate covers were manufactured.

(Evaluation 1: Measurement of liquid crystal display device surface temperature during irradiation of sunlight)
A "RF100V200W-W/D" reflex bulb manufactured by Panasonic Corporation was used as the simulated sunlight, and it was placed 10 cm above the gate cover surface of the HUD device for evaluation.
Then, the surface temperature of the liquid crystal display (LCD) after being irradiated for 100 hours in an environment of 25° C. and 60% RH is measured by a surface thermometer (manufactured by Keyence Co., Ltd., an ultra-small/small-spot infrared radiation thermometer IT2). -50).

(Evaluation 2: Observation of appearance of gate cover after irradiation of sunlight)
A "RF100V200W-W/D" reflex bulb manufactured by Panasonic Corporation was used as simulated sunlight from the upper surface side of the windshield, and was placed 10 cm above the gate cover surface of the HUD device for evaluation.
Then, the external appearance of the gate cover after irradiation for 200 hours under the environment of 25° C. and 60% RH was visually observed, and the durability was evaluated according to the following criteria.
⊚: No deformation or swelling was observed in the gate cover ◯: Almost no deformation or swelling was observed in the gate cover Δ: Weak deformation was observed in part of the gate cover, but practically acceptable X: The gate cover has obvious deformation and swelling, which is a problem in practical use.

[Evaluation of visibility of display image]
The speed information and the character information are projected on the projection screen of each HUD device, the presence or absence of rainbow unevenness in the displayed image and the image sharpness are visually observed, and the visibility of the displayed image is evaluated according to the following criteria. I went.
◯: The display image is a highly sharp display image with no rainbow unevenness. Δ: A slight rainbow unevenness is observed in the display image, but the sharpness of the display image is good. , Clear rainbow unevenness is generated and the sharpness of the display image is slightly low XX: Strong rainbow unevenness occurs in the display image and the sharpness of the display image is low. The results obtained as described above are shown in Table II. ..

As is clear from the results shown in Table II, the gate cover having the configuration defined in the present invention has a low phase difference characteristic, and has excellent transmittance in the visible light wavelength region and excellent reflectance in the infrared region. It can be seen that the liquid crystal display device (LCD) has characteristics and can prevent the temperature of the liquid crystal display device (LCD) from rising when it is exposed to sunlight and prevent damage to the gate cover due to thermal energy when incorporated into a HUD device. ..

1 Head-up display (HUD device)
2 Windshield 3 Gate-up display gate cover 4 Magnifying glass 5 Cold mirror 6 Hot mirror 7 Liquid crystal display (LCD)
11 Resin Base Material 12 Infrared Absorption Layer B
13 Infrared reflective layer 14 Polarizing layer (polarizer)
16 Film for polarizing plate B
17 Film A for polarizing plate
18 Infrared absorbing layer A
19 Protective Film 20 Hard Coat Layer 21 Polarizing Plate 30 Liquid Crystal Display Device 31 First Polarizing Plate 31a First Polarizer 32 Liquid Crystal Cell 33 Second Polarizing Plate 33a Second Polarizer L Sunlight U1 Polarizing Unit U2 Infrared Absorption layer unit B
U3 Infrared absorption layer unit A

Claims (9)

A gate cover for a head-up display in which an infrared absorption layer and an infrared reflection layer are provided on a resin substrate,
The in-plane retardation value of the resin base material is in the range of 0 nm or more and less than 100 nm when a light beam having an incident angle of 0° and a wavelength of 550 nm is incident.
The infrared absorbing layer contains the following infrared absorbent-1 and infrared absorbent-2,
A gate cover for a head-up display, which has an average transmittance of 80% or more in a visible light wavelength region of 380 to 740 nm and an average reflectance of 15% or more in a near infrared wavelength region of 750 to 1500 nm.
(Infrared absorber)
Infrared absorbing agent-1: Near infrared absorbing organic compound infrared absorbing agent having a maximum absorption peak in the near infrared wavelength region of 750 to 1200 nm-2: Metal oxide infrared absorbing agent The gate cover for a head-up display according to claim 1, wherein the near-infrared absorber-1 is selected from metal complex dyes, immonium dyes, diimmonium dyes, and polymethine dyes. The infrared absorber-2 is selected from tin-doped indium oxide (ITO), cesium-doped tungsten oxide (CWO), antimony-doped tin oxide (ATO), gallium-doped zinc oxide (GZO) and aluminum-doped zinc oxide (AZO). A gate cover for a head-up display according to claim 1 or 2. The value of the mass ratio of the infrared absorbing agent-2 to the infrared absorbing agent-1 is within the range of 1.0 to 6.0. Gate cover for head-up display described in. Furthermore, it has a polarizing layer and the average transmittance of linearly polarized light in the visible light wavelength region of 380 to 740 nm is 80% or more, and any one of claims 1 to 4 is characterized. Gate cover for the head-up display described. The gate cover for a head-up display according to any one of claims 1 to 5, wherein the infrared reflective layer has a dielectric multilayer film structure. The gate cover for a head-up display according to any one of claims 1 to 6, wherein the infrared reflective layer contains inorganic fine particles. The layer containing the infrared absorbent-2, the infrared reflective layer, and the layer containing the infrared absorbent-1 are arranged in this order on the resin base material. The gate cover for a head-up display according to any one of claims 1 to 7. The gate cover for a head-up display according to any one of claims 1 to 8, which is provided in a head-up display mounted on an automobile, a train, an aircraft or a ship.

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