WO2018110066A1

WO2018110066A1 - Windshield glass, head-up display system, and laminated film

Info

Publication number: WO2018110066A1
Application number: PCT/JP2017/037322
Authority: WO
Inventors: 昭裕安西; 渉馬島
Original assignee: 富士フイルム株式会社
Priority date: 2016-12-13
Filing date: 2017-10-16
Publication date: 2018-06-21
Also published as: JP2018097152A

Abstract

The windshield glass according to the present invention comprises, in order, a first glass board, a first resin film, a half mirror film, a second resin film, and a second glass board, and further comprises a substrate, wherein the half mirror film includes a circular polarized light reflection layer, the circular polarized light reflection layer includes a cholesteric liquid crystal layer, the half mirror film is adjacent to the substrate, the substrate has an elastic modulus of 3-10 GPa and a thickness of 150-500μm. The windshield glass has a reduced strain that can be visually observed in a half mirror film portion. The windshield glass can be used in a head-up display system.

Description

Windshield glass, head-up display system, and laminated film

The present invention relates to a windshield glass. The present invention also relates to a head-up display system using a windshield glass and a laminated film that can be used for the windshield glass.

A half mirror film is provided on the intermediate layer of windshield glass, which has a structure in which two glass plates are bonded via an intermediate layer, thereby simultaneously displaying images projected in the head-up display system and the scenery in front. It is possible to obtain a projection image display member that can be made to operate. Patent Document 1 discloses that an intermediate layer is formed by sandwiching a half mirror film including a cholesteric liquid crystal layer between two resin films such as a polyvinyl butyral film.

WO2016 / 052367

However, when a half mirror film including a cholesteric liquid crystal layer is provided in the intermediate layer of the laminated glass as described in Patent Document 1, distortion is visually confirmed in the half mirror film portion, and the aesthetics as a windshield glass is improved. There was room for. This is presumed to be caused by orange-peel irregularities due to the difference in shrinkage between the resin film and the half mirror film during pressure bonding and heating during laminated glass production. It was done.

The present invention has been made to solve the above problems, and in a windshield glass having a structure in which a half mirror film is provided in an intermediate layer of a laminated glass, distortion that is visually confirmed in the half mirror film portion is reduced. An object is to provide a windshield glass.

The inventor has intensively studied under the above problems, and the orange peel is less likely to occur when the half mirror film is integrated with a highly rigid base material at the time of pressure bonding or heating at the time of laminated glass production. The present invention was completed.

That is, the present invention provides the following [1] to [18].
[1] A windshield glass including a first glass plate, a first resin film, a half mirror film, a second resin film, and a second glass plate in this order,
Further including a substrate,
The half mirror film includes a circularly polarized light reflection layer,
The circularly polarized light reflection layer includes a cholesteric liquid crystal layer,
The half mirror film is adjacent to the base material,
A windshield glass in which the base material has an elastic modulus of 3 GPa to 10 GPa and the base material has a thickness of 150 μm to 500 μm.
[2] The windshield glass according to [1], wherein the base material has an elastic modulus of 4 GPa to 8 GPa and the base material has a thickness of 170 μm to 300 μm.
[3] The windshield glass according to [1] or [2], wherein the half mirror film is bonded to the base material by an adhesive layer.
[4] The windshield glass according to [3], wherein the adhesive layer has a thickness of 0.5 μm to 10 μm.

[5] The windshield glass according to any one of [1] to [4], wherein the half mirror film is adjacent to the base material at a part of a main surface of the base material.
[6] The windshield glass according to any one of [1] to [5], including a retardation layer.
[7] The windshield glass according to [6], wherein the retardation layer is a λ / 2 retardation layer.
[8] The windshield glass according to [6] or [7], wherein the half mirror film includes the retardation layer.
[9] The windshield glass according to [6] or [7], wherein the substrate is the retardation layer.
[10] The windshield glass according to any one of [1] to [8], wherein the substrate is a polyethylene terephthalate film.

[11] The circularly polarized light reflecting layer includes three or more cholesteric liquid crystal layers having a central wavelength of selective reflection in a visible light region,
The windshield glass according to any one of [1] to [10], wherein the central wavelengths of selective reflection of each of the three or more cholesteric liquid crystal layers are different from each other.
[12] including a λ / 2 retardation layer,
The circularly polarized light reflection layer includes four or more cholesteric liquid crystal layers,
One of the four or more cholesteric liquid crystal layers is a cholesteric liquid crystal layer having a central wavelength of selective reflection at 350 nm or more and less than 490 nm,
The windshield glass according to [11], wherein the central wavelengths of selective reflection of each of the four or more cholesteric liquid crystal layers are different from each other.
[13] The cholesteric liquid crystal layer closest to the λ / 2 retardation layer among the four or more cholesteric liquid crystal layers is a cholesteric liquid crystal layer having a selective reflection center wavelength of 350 nm or more and less than 490 nm. Windshield glass.

[14] The windshield glass according to any one of [1] to [13], wherein any one or more selected from the group consisting of the first resin film and the second resin film includes polyvinyl butyral.
[15] A head-up display system including the windshield glass according to any one of [1] to [14] and a projector.
[16] A head-up display system including the windshield glass and projector according to any one of [1] to [8],
A head-up display system in which the base material, the half mirror film, and the projector are arranged in this order.
[17] A head-up display system including the windshield glass and the projector according to any one of [6] to [9],
A head-up display system in which the circularly polarized light reflecting layer, the retardation layer, and the projector are arranged in this order.
[18] A laminated film comprising a substrate and a half mirror film,
The half mirror film is bonded to the substrate with an adhesive layer on a part of the main surface of the substrate,
The half mirror film includes a circularly polarized light reflection layer,
The circularly polarized light reflection layer includes three or more cholesteric liquid crystal layers having a central wavelength of selective reflection in the visible light region,
A laminated film in which the substrate is a polyethylene terephthalate film, the elastic modulus of the substrate is 3 GPa to 10 GPa, and the thickness of the substrate is 150 μm to 500 μm.

According to the present invention, in the windshield glass having a laminated glass structure including a half mirror film in the intermediate layer, it is possible to provide a windshield glass that is visually confirmed and is not distorted due to the half mirror film. This windshield glass can be used in a head-up display system. Moreover, the laminated film suitable for preparation of said windshield glass is provided.

It is a figure which shows typically the layer structure of the windshield glass produced in the Example.

Hereinafter, the present invention will be described in detail.
In the present specification, “to” is used in the sense of including the numerical values described before and after it as lower and upper limits.
In this specification, an angle (for example, an angle such as “90 °”) and a relationship thereof (for example, “parallel”, “horizontal”, “vertical”, etc.) are allowable errors in the technical field to which the present invention belongs. The range of For example, it means that the angle is within the range of strict angle ± 10 °, and the error from the strict angle is preferably 5 ° or less, and more preferably 3 ° or less.

In this specification, when referring to the area and shape of a film-like or layered thing, unless otherwise specified, it means the area and the shape of the main surface (front surface or back surface), respectively.

In this specification, “selective” for circularly polarized light means that the amount of light of either the right circularly polarized component or the left circularly polarized component of light is greater than that of the other circularly polarized component. Specifically, when referred to as “selective”, the degree of circular polarization of light is preferably 0.3 or more, more preferably 0.6 or more, and even more preferably 0.8 or more. More preferably, it is substantially 1.0. Table In _{_{/ (I R + I L)}} | Here, the degree of circular polarization, the intensity of the right circularly polarized light component of the light I _R, when the strength of the left-handed circularly polarized light component and I _{_L,} | I _R -I _L Is the value to be

In this specification, “sense” for circularly polarized light means right circularly polarized light or left circularly polarized light. The sense of circularly polarized light is right-handed circularly polarized light when the electric field vector tip turns clockwise as time increases when viewed as the light travels toward you, and left when it turns counterclockwise. Defined as being circularly polarized.

In this specification, the term “sense” is sometimes used for the twist direction of the spiral of the cholesteric liquid crystal. When the twist direction (sense) of the spiral of the cholesteric liquid crystal is right, it reflects right circularly polarized light and transmits left circularly polarized light. When the sense is left, it reflects left circularly polarized light and transmits right circularly polarized light.

In this specification, “light” means visible light and natural light (unpolarized light) unless otherwise specified. Visible light is light having a wavelength that can be seen by the human eye among electromagnetic waves, and usually indicates light having a wavelength range of 380 nm to 780 nm.
In this specification, the measurement of the light intensity required in connection with the calculation of the light transmittance may be performed by using, for example, a normal visible spectrum meter and measuring the reference as air.
In the present specification, the term “reflected light” or “transmitted light” is used to mean scattered light and diffracted light.

In addition, the polarization state of each wavelength of light can be measured using a spectral radiance meter or a spectrometer equipped with a circularly polarizing plate. In this case, the intensity of light measured through the right circularly polarizing plate corresponds to I _R , and the intensity of light measured through the left circularly polarizing plate corresponds to I _L. Moreover, even if a circularly polarizing plate is attached to an illuminometer or a spectrum meter, the measurement can be performed. The ratio can be measured by attaching a right circular polarized light transmission plate, measuring the right circular polarized light amount, attaching a left circular polarized light transmission plate, and measuring the left circular polarized light amount.

In this specification, p-polarized light means polarized light that vibrates in a direction parallel to the light incident surface. The incident surface means a surface that is perpendicular to a reflecting surface (such as a windshield glass surface) and includes incident light rays and reflected light rays. In p-polarized light, the vibration plane of the electric field vector is parallel to the incident plane. In this specification, s-polarized light means polarized light that vibrates in a direction perpendicular to the light incident surface.
In this specification, the front phase difference is a value measured using an AxoScan manufactured by Axometrics. The measurement wavelength is 550 nm. The front phase difference may be a value measured by making light having a wavelength in the visible light wavelength region incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments). When selecting the measurement wavelength, the wavelength selection filter can be exchanged manually, or the measurement value can be converted by a program or the like.

In this specification, the birefringence (Δn) of a liquid crystal compound is the same as that described in “Liquid Crystal / Fundamentals (Mitsoji Okano, Keisuke Kobayashi)” p. It is a value measured according to the method described in 214. Specifically, Δn at 60 ° C. can be obtained by injecting a liquid crystal compound into a wedge-shaped cell, irradiating it with light having a wavelength of 550 nm, and measuring the refraction angle of transmitted light.

In this specification, “projection image” means an image based on the projection of light from a projector to be used, not a surrounding landscape such as the front. The projected image is observed as a virtual image that appears above the projected image display portion of the windshield glass as viewed from the observer.
In this specification, “screen image” means an image displayed on a drawing device of a projector or an image drawn on an intermediate image screen or the like by the drawing device. In contrast to a virtual image, an image is a real image.
Both the image and the projected image may be a single color image, a multicolor image of two or more colors, or a full color image.

<< Windshield Glass >>
In this specification, the windshield glass means a window glass for vehicles such as cars, trains, airplanes, ships, play equipment and the like. The windshield glass is preferably a windshield in the direction of travel of the vehicle. The windshield glass is preferably a vehicle windshield.

The windshield glass may be flat. The windshield glass may be formed for incorporation into an applied vehicle, and may have a curved surface, for example. In a windshield glass formed for a vehicle to be applied, a direction that is upward (vertically upward) and a surface that is an observer side can be specified during normal use. In the present specification, when the windshield glass or the projected image display part is vertically above, it means the direction that is vertically above when it can be specified as described above.

The windshield glass of the present invention has a laminated glass structure in which two glass plates are bonded via an intermediate layer, and includes a first glass plate, a first resin film, a half mirror film, and a second glass plate. A resin film and a second glass plate are included in this order. The windshield glass of the present invention further includes a specific base material, and the half mirror film is adjacent to the base material.

<Glass plate>
In the present specification, in the windshield glass, the glass plate on the outside is referred to as the first glass plate, and the glass plate on the indoor side is referred to as the second glass plate. In other words, the glass plate located farther from the observer (driver) side is called the first glass plate, and the glass plate located closer is called the second glass plate.
In the present specification, the term “glass plate” means both the first glass plate and the second glass plate.

As the glass plate, a glass plate generally used for windshield glass can be used. The thickness of the glass plate is not particularly limited, but is preferably about 0.5 mm to 5 mm, more preferably 1 mm to 3 mm, and further preferably 1.6 mm to 2.3 mm. The thicknesses of the first glass plate and the second glass plate may be the same or different from each other. For example, the first glass plate may be 1.9 mm to 2.5 mm, and the second glass plate may be 1.6 mm to 1.9 mm.

The glass plate may be subjected to surface treatment for imparting water repellency, hydrophilicity, or antifogging property to the surface thereof.
The glass plate is preferably cut into the shape of windshield glass. Moreover, it is preferable to have a curved surface. The curved surface can be provided by placing the cut glass plate on a jig having the same curvature as the windshield glass to be manufactured and heating (for example, 600 to 700 ° C.).

<Resin film>
In this specification, in the windshield glass, the resin film on the outside is referred to as a first resin film, and the resin film on the indoor side is referred to as a second resin film. In other words, the resin film located farther from the observer (driver) side is called the first resin film, and the resin film located closer is called the second resin film. The first resin film and the second resin film may be the same or different in material, thickness, and the like. The materials are preferably the same, and more preferably the materials and thickness are the same.

In the present specification, the term “resin film” means both the first resin film and the second resin film.
The resin film may have the same shape and area as the first glass plate. For example, in the laminated glass manufacturing process, after the resin film unwound from the roll form is sandwiched between the first glass plate and the second glass plate, it may be trimmed into the shape of the first glass plate. .

As a resin film, a well-known resin film can be used as a sheet | seat used for the intermediate | middle layer of a laminated glass. The resin film contains a resin as a main component. The main component refers to a component that occupies a ratio of 50% by mass or more of the resin film.
The resin is preferably a synthetic resin. For example, a thermoplastic resin can be used as the resin. Examples of the thermoplastic resin include thermoplastic resins conventionally used for interlayer applications in laminated glass, such as polyvinyl acetal, polyvinyl chloride, saturated polyester, polyurethane, ethylene-vinyl acetate copolymer, ethylene. -Ethyl acrylate copolymer and the like. Among these, polyvinyl acetal is preferable from the viewpoints of transparency, strength, light resistance, and the like.

Polyvinyl acetal is a general term for resins obtained by acetalizing polyvinyl alcohol with an aldehyde in the presence of an acid. For example, polyvinyl formal acetalized with formalin (formaldehyde 37% aqueous solution) as an aldehyde, butanol (butyl alcohol) as an aldehyde. Examples include acetalized polyvinyl butyral (hereinafter sometimes referred to as “PVB”).

Of the above resins, polyvinyl butyral or ethylene-vinyl acetate copolymer is preferable, and polyvinyl butyral is more preferable. As described above, polyvinyl butyral can be obtained by acetalizing polyvinyl alcohol with butyraldehyde. The preferable lower limit of the degree of acetalization of the polyvinyl butyral is 40%, the preferable upper limit is 85%, the more preferable lower limit is 60%, and the more preferable upper limit is 75%.

Polyvinyl alcohol is usually obtained by saponifying polyvinyl acetate, and polyvinyl alcohol having a saponification degree of 80 to 99.8 mol% is generally used.
Moreover, the preferable minimum of the polymerization degree of the said polyvinyl alcohol is 200, and a preferable upper limit is 3000. When the polymerization degree of polyvinyl alcohol is 200 or more, the penetration resistance of the obtained laminated glass is difficult to decrease, and when it is 3000 or less, the moldability of the resin film is good, and the rigidity of the resin film does not increase too much. Good workability. A more preferred lower limit is 500, and a more preferred upper limit is 2000.

The resin is also preferably plasticized by the addition of a plasticizer. For example, as the plasticizer, phosphate ester, carboxylic acid ester, sugar ester, polycondensation ester, or the like is used.
The addition amount of the plasticizer is preferably 10 parts by mass or more and 80 parts by mass or less with respect to 100 parts by mass of the resin. By adding 10 parts by mass or more of a plasticizer, the thermoplastic resin can be sufficiently plasticized. Moreover, the intensity | strength of a resin layer can fully be maintained by the addition amount of a plasticizer being 80 mass parts or less.

In addition to the plasticizer, the resin film or the composition for forming the resin film is an infrared shielding fine particle, an adhesion adjusting agent, a coupling agent, a surfactant, an antioxidant, a heat stabilizer, a light stabilizer, One type or two or more types of various additives such as an ultraviolet absorber, a fluorescent agent, a dehydrating agent, an antifoaming agent, an antistatic agent, and a flame retardant may be included.

The thickness of the resin film is, for example, preferably 0.1 mm to 1.5 mm, and more preferably 0.2 mm to 1.0 mm.

<Half mirror film>
The windshield glass of the present invention includes a half mirror film in the intermediate layer of the laminated glass.
By providing the half mirror film in the intermediate layer of the laminated glass, for example, a projected image display portion capable of simultaneously displaying an image projected in a head-up display system and a front landscape can be formed on the windshield glass. .

In this specification, the projected image display part is a part capable of displaying a projected image with reflected light, and may be any part capable of displaying the projected image projected from a projector or the like so as to be visible.
When the windshield glass of the present invention is used in a head-up display system, an image projected from a projector can be displayed on a half mirror film portion so as to be visible, and a half mirror is displayed from the same surface side on which the image is displayed. When observing the film, information or scenery on the opposite side can be observed simultaneously. That is, the half mirror film has a function as an optical path combiner that displays external light and video light in a superimposed manner.

The half mirror film may be provided on the entire surface of the windshield glass, or may be provided in part with respect to the entire area of the windshield glass, but is preferably provided in part. When it is a part, the upper limit is 90% or less, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, etc. with respect to the total area of the windshield glass. The lower limit may be 1% or more, 3% or more, 5% or more, 7% or more, 10% or more. Moreover, when it is a part, the half mirror film may be provided in any position of the windshield glass, but when used as a head-up display system, the position is easily visible from an observer (for example, a driver). Are preferably provided so that a virtual image is shown. For example, the position where the half mirror film is provided may be determined from the relationship between the position of the driver's seat of the applied vehicle and the position where the projector is installed. Specifically, it is preferably disposed at an angle that the driver looks down, and is preferably disposed at a position below the center of the windshield glass.

In the windshield glass of the present invention, the half mirror film may have a flat shape that does not have a curved surface, but may have a curved surface, and has a concave or convex shape as a whole. The image may be displayed enlarged or reduced.
The thickness of the half mirror film is preferably 2.5 μm to 35 μm, more preferably 3.0 μm to 30 μm, and even more preferably 3.5 μm to 25 μm.

The half mirror film only needs to have a function as a half mirror for at least projection light. However, for example, it does not need to function as a half mirror for light in the entire visible light range. Moreover, the half mirror film should just have said function with respect to the light of at least one part incident angle.

It is preferable that the half mirror film has visible light transmittance in order to enable observation of information or scenery on the opposite surface side. The half mirror film may have a light transmittance of 40% or more, preferably 50% or more, more preferably 60% or more, and further preferably 70% or more in the visible light wavelength region. The light transmittance is the light transmittance determined by the method described in JIS-K7105.

Half mirror film includes a circularly polarized reflective layer. The half mirror film may further include a retardation layer. In this case, the circularly polarized light reflecting layer and the retardation layer may be prepared separately and adhered to each other to form a half mirror film, or the retardation layer on the circularly polarized light reflecting layer (cholesteric liquid crystal layer). A half mirror film may be formed by forming a circularly polarized light reflecting layer (cholesteric liquid crystal layer) on the retardation layer.

The half mirror film may include layers such as a second retardation layer, an alignment layer, a support, and an adhesive layer described later in addition to the circularly polarized light reflection layer and the retardation layer.
The half mirror film used for producing the windshield glass of the present invention may be a film shape, a sheet shape, or a plate shape. The half mirror film may be formed as a thin film in a roll shape or the like, and thereafter used for producing the windshield glass of the present invention.

[Circularly polarized reflective layer]
The circularly polarized light reflecting layer is a layer that reflects light. The circularly polarized light reflection layer includes a cholesteric liquid crystal layer. The circularly polarized light reflecting layer may include other layers such as an alignment layer.
The thickness of the circularly polarized light reflection layer is preferably 2.0 μm to 30 μm, more preferably 2.5 μm to 25 μm, and even more preferably 3.0 μm to 20 μm.

(Cholesteric liquid crystal layer)
In this specification, a cholesteric liquid crystal layer means a layer in which a cholesteric liquid crystal phase is fixed. The cholesteric liquid crystal layer is sometimes simply referred to as a liquid crystal layer.
The cholesteric liquid crystal layer may be a layer that maintains the orientation of the liquid crystal compound that is in the cholesteric liquid crystal phase. A cholesteric liquid crystal layer typically has a polymerizable liquid crystal compound in an aligned state of a cholesteric liquid crystal phase, and is then polymerized and cured by ultraviolet irradiation, heating, etc. to form a layer having no fluidity, and at the same time, Any layer may be used as long as the orientation is not changed by an external field or an external force. In the cholesteric liquid crystal layer, it is sufficient that the optical properties of the cholesteric liquid crystal phase are maintained in the layer, and the liquid crystal compound in the layer may no longer exhibit liquid crystallinity. For example, the polymerizable liquid crystal compound may have a high molecular weight due to a curing reaction and may no longer have liquid crystallinity.

It is known that the cholesteric liquid crystal phase exhibits circularly polarized light selective reflection that selectively reflects the circularly polarized light of either the right circularly polarized light or the left circularly polarized light and transmits the circularly polarized light of the other sense. In this specification, the circularly polarized light selective reflection is sometimes simply referred to as selective reflection.
Many films formed from a composition containing a polymerizable liquid crystal compound have been known as a film containing a layer in which a cholesteric liquid crystal phase exhibiting circularly polarized light selectively is fixed. You can refer to the technology.

The central wavelength λ of selective reflection of the cholesteric liquid crystal layer depends on the pitch P (= helical period) of the helical structure in the cholesteric phase, and follows the relationship between the average refractive index n of the cholesteric liquid crystal layer and λ = n × P. In this specification, the central wavelength λ of selective reflection of the cholesteric liquid crystal layer means a wavelength at the center of gravity of the reflection peak of the circularly polarized reflection spectrum measured from the normal direction of the cholesteric liquid crystal layer.

The selective reflection center wavelength and the half-value width of the cholesteric liquid crystal layer can be obtained as follows.
When the transmission spectrum of the cholesteric liquid crystal layer (measured from the normal direction of the cholesteric liquid crystal layer) is measured using a spectrophotometer, a drop in transmittance is observed in the selective reflection band. Of the two wavelengths that have an intermediate (average) transmittance between the minimum transmittance of this peak and the transmittance before the decrease, the wavelength value on the short wavelength side is λ _l (nm), and the wavelength value on the long wavelength side Is λ _h (nm), the center wavelength λ and the half-value width Δλ of selective reflection can be expressed by the following equations.
λ = (λ _l + λ _h ) / 2
Δλ = (λ _h −λ _l )
The selective reflection center wavelength obtained as described above substantially matches the wavelength at the center of gravity of the reflection peak of the circularly polarized reflection spectrum measured from the normal direction of the cholesteric liquid crystal layer. Examples of the spectrophotometer include UV3150 manufactured by Shimadzu Corporation and V-670 manufactured by JASCO.

As can be seen from the above relationship of λ = n × P, the center wavelength of selective reflection can be adjusted by adjusting the pitch of the helical structure. The cholesteric liquid crystal layer exhibiting selective reflection in the visible light region preferably has a center wavelength of selective reflection in the visible light region. By adjusting the n value and the P value, for example, the center wavelength λ is adjusted to selectively reflect either the right circularly polarized light or the left circularly polarized light with respect to red light, green light, and blue light. be able to.

In a head-up display system, a windshield glass is used so that light is incident obliquely with respect to a circularly polarized reflective layer in order to reduce double images caused by reflection of projection light on the front or back surface of the glass. It is preferable. Thus, when light is incident on the cholesteric liquid crystal layer at an angle, the center wavelength of selective reflection is shifted to the short wavelength side. Therefore, it is possible to adjust n × P so that λ calculated according to the above formula of λ = n × P is on the long wavelength side with respect to the wavelength of selective reflection required for the projected image display. preferable. In the cholesteric liquid crystal layer having a refractive index n ₂ , the center wavelength of selective reflection when a light beam passes at an angle of θ ₂ with respect to the normal direction of the cholesteric liquid crystal layer (helical axis direction of the cholesteric liquid crystal layer) is λ _d . Λ _d is expressed by the following equation.
λ _d = n ₂ × P × cos θ ₂

For example, light incident from the λ / 2 phase difference layer side at an angle of 45 ° to 70 ° with respect to the normal of the projected image display portion in air having a refractive index of 1 is normally about 1.45 to 1.80. Is transmitted through the λ / 2 retardation layer at an angle of 23 ° to 40 ° with respect to the normal line of the projected image display portion, and enters the cholesteric liquid crystal layer having a refractive index of about 1.61. Since light passes through the cholesteric liquid crystal layer at an angle of 26 ° to 36 °, n × P may be adjusted by inserting this angle and the center wavelength of the desired selective reflection into the above equation.
Since the pitch of the cholesteric liquid crystal phase depends on the type of chiral agent used together with the polymerizable liquid crystal compound or the concentration of the chiral agent, the desired pitch can be obtained by adjusting these. For the method of measuring spiral sense and pitch, use the methods described in “Introduction to Liquid Crystal Chemistry Experiments”, edited by the Japanese Liquid Crystal Society, Sigma Publishing 2007, page 46, and “Liquid Crystal Handbook”, Liquid Crystal Handbook Editing Committee, page 196. be able to.

The circularly polarized light reflecting layer preferably includes three or more cholesteric liquid crystal layers. The circularly polarized light reflection layer preferably includes three or more cholesteric liquid crystal layers having a central wavelength of selective reflection in the visible light region. Further, it is preferable that the central wavelengths of selective reflection of the three or more cholesteric liquid crystal layers are different from each other. The circularly polarized light reflection layer preferably has an apparent selective reflection center wavelength with respect to red light, green light, and blue light. The apparent center wavelength of selective reflection means the wavelength at the center of gravity of the reflection peak of the circularly polarized reflection spectrum of the cholesteric liquid crystal layer measured from the observation direction in practical use. By having an apparent central wavelength of selective reflection for red light, green light, and blue light, it is possible to display a full-color projected image. Specifically, the circularly polarized light reflection layer may include a cholesteric liquid crystal layer that selectively reflects red light, a cholesteric liquid crystal layer that selectively reflects green light, and a cholesteric liquid crystal layer that selectively reflects blue light. preferable. The circularly polarized light reflecting layer has, for example, a cholesteric liquid crystal layer having a central wavelength of selective reflection at 490 nm to 600 nm, a cholesteric liquid crystal layer having a central wavelength of selective reflection at 600 nm to 680 nm, and a central wavelength of selective reflection at 680 nm to 850 nm. It is preferable to include a cholesteric liquid crystal layer.

Displaying a clear projected image with high light utilization efficiency by adjusting the center wavelength of selective reflection of the cholesteric liquid crystal layer to be used according to the emission wavelength range of the light source used for projection and the usage of the circularly polarized reflective layer Can do. In particular, by adjusting the central wavelength of selective reflection of each cholesteric liquid crystal layer in accordance with the emission wavelength range of the light source used for projection, a clear color projection image can be displayed with high light utilization efficiency. Examples of usage of the circularly polarized light reflecting layer include the incident angle of the projected light on the circularly polarized light reflecting layer, the direction in which the projected image is observed, and the like.

In the windshield glass of the present invention, it is preferable that the circularly polarized light reflection layer includes four or more cholesteric liquid crystal layers, and the central wavelengths of selective reflection of the four or more cholesteric liquid crystal layers are different from each other.

As each cholesteric liquid crystal layer, a cholesteric liquid crystal layer whose spiral sense is either right or left is used. The sense of reflected circularly polarized light in the cholesteric liquid crystal layer coincides with the sense of a spiral. The spiral senses of the cholesteric liquid crystal layers having different selective reflection center wavelengths may all be the same or may include different ones, but are preferably the same.

The full width at half maximum Δλ (nm) of the selective reflection band showing selective reflection depends on the relationship of Δλ = Δn × P, where Δλ depends on the birefringence Δn of the liquid crystal compound and the pitch P. Therefore, the width of the selective reflection band can be controlled by adjusting Δn. Δn can be adjusted by adjusting the type and mixing ratio of the polymerizable liquid crystal compound or by controlling the temperature at the time of alignment fixation.
In order to form one type of cholesteric liquid crystal layer having the same selective reflection center wavelength, a plurality of cholesteric liquid crystal layers having the same pitch P and the same spiral sense may be stacked. By laminating cholesteric liquid crystal layers having the same pitch P and the same spiral sense, the circularly polarized light selectivity can be increased at a specific wavelength.

The half width Δλ of selective reflection can be 15 nm to 200 nm, 15 nm to 150 nm, 20 nm to 100 nm, or the like. The circularly polarized light reflection layer preferably includes at least one cholesteric liquid crystal layer having a selective reflection half width Δλ of 50 nm or less. In the present specification, a cholesteric liquid crystal layer having a selective reflection half-value width Δλ of 50 nm or less may be referred to as a narrow-band selective reflection layer. More preferably, the circularly polarized light reflecting layer includes two narrow band selective reflecting layers. In particular, the cholesteric liquid crystal layer having the apparent center wavelength of selective reflection for green light and blue light is preferably a narrow-band selective reflection layer. Since the cholesteric liquid crystal layer having the apparent center wavelength of selective reflection with respect to green light and blue light is a narrow-band selective reflection layer, a projection image that provides a clear projection image without impairing the transparency of the windshield glass. It is possible to form an image display part.

The thickness of the cholesteric liquid crystal layer is preferably 0.3 μm to 10 μm, more preferably 0.4 μm to 8.0 μm, and even more preferably 0.5 μm to 6.0 μm.

When laminating a plurality of cholesteric liquid crystal layers, a separately prepared cholesteric liquid crystal layer may be laminated using an adhesive or the like, and the polymerizable liquid crystal is directly applied to the surface of the previous cholesteric liquid crystal layer formed by the method described later. A liquid crystal composition containing a compound or the like may be applied and the alignment and fixing steps may be repeated, but the latter is preferred. By forming the next cholesteric liquid crystal layer directly on the surface of the previously formed cholesteric liquid crystal layer, the orientation direction of the liquid crystal molecules on the air interface side of the previously formed cholesteric liquid crystal layer and the cholesteric liquid crystal layer formed thereon This is because the orientation directions of the lower liquid crystal molecules coincide with each other, and the polarization property of the laminate of cholesteric liquid crystal layers is improved. Moreover, interference unevenness that may be caused by unevenness in the thickness of the adhesive layer is not observed.

(Short wavelength cholesteric liquid crystal layer)
When the circularly polarized light reflection layer includes four or more cholesteric liquid crystal layers, one of these cholesteric liquid crystal layers is a cholesteric liquid crystal layer (hereinafter referred to as “short wavelength cholesteric liquid crystal layer) having a central wavelength of selective reflection at 350 nm or more and less than 490 nm. It is also preferable to include a “liquid crystal layer”. In the case where the configuration including the circularly polarized light reflection layer and the λ / 2 retardation layer is provided on the windshield glass as the projected image display portion, the present inventors have observed the projected image display portion in the windshield glass under the external light. It was discovered that the color (especially yellow) was confirmed. By using a circularly polarized reflective layer including a cholesteric liquid crystal layer having a central wavelength of selective reflection at 350 nm or more and less than 490 nm, the above-mentioned color is felt in the projected image display part even when the windshield glass is observed under the external light. The projection image display part can be made inconspicuous from the outside. In the head-up display system, it is preferable that the optical design is made on the assumption that light is incident obliquely with respect to the circularly polarized reflective layer in order to reduce the double image using the Brewster angle. Thus, when trying to design a circularly polarized light reflection layer having a central wavelength of apparent selective reflection for red light, green light, and blue light, respectively, the light from the normal direction of the circularly polarized light reflection layer The blue light component is relatively reduced in the reflected light, and a yellowish color can be generated. By using a cholesteric liquid crystal layer having a central wavelength of selective reflection at 350 nm or more and less than 490 nm, it is considered that the blue light component of the reflected light is increased and the yellow color is eliminated.

By using a cholesteric liquid crystal layer having a central wavelength of selective reflection at 350 nm or more and less than 490 nm, it is possible to reduce glare that can be felt through polarized sunglasses when observing external light through a projected image display part. Normally, s-polarized light based on reflected light from the ground or water surface that is not visually recognized through polarized sunglasses can be converted into a light component that is visually recognized by changing the polarization state at the projected image display site, and this light component is 350 nm. This is considered to be reduced by using a cholesteric liquid crystal layer having a central wavelength of selective reflection below 490 nm.

The cholesteric liquid crystal layer having a central wavelength of selective reflection at 350 nm or more and less than 490 nm preferably has a central wavelength of selective reflection at 370 nm to 485 nm, more preferably has a central wavelength of selective reflection at 390 nm to 480 nm. More preferably, it has a central wavelength of selective reflection at 470 nm.
The short wavelength cholesteric liquid crystal layer may have an apparent selective reflection center wavelength of 280 nm or more and less than 420 nm, preferably 300 nm or more and less than 410 nm, preferably 320 nm or more and less than 400 nm when used in a head-up display system. Is more preferably 340 nm or more and less than 395 nm.

When the windshield glass of the present invention includes a retardation layer, the short-wavelength cholesteric liquid crystal layer in the circularly polarized light reflection layer is the most retardation layer (first retardation described later) among four or more cholesteric liquid crystal layers. Preferably it is on the layer) side. This is because the double image is further reduced.
In the circularly polarized light reflection layer, the cholesteric liquid crystal layer is preferably arranged in order from the one having the shortest central wavelength of selective reflection as viewed from the phase difference layer (first phase difference layer described later) side. For example, a retardation layer, a cholesteric liquid crystal layer having a central wavelength of selective reflection at 350 nm to less than 490 nm, a cholesteric liquid crystal layer having a central wavelength of selective reflection at 490 to 600 nm, and a cholesteric liquid crystal having a central wavelength of selective reflection at 600 to 680 nm It is preferable that a cholesteric liquid crystal layer having a central wavelength of selective reflection at 680 nm to 850 nm is disposed in this order.

(Method for producing cholesteric liquid crystal layer)
Hereinafter, a manufacturing material and a manufacturing method of the cholesteric liquid crystal layer will be described.
Examples of the material used for forming the cholesteric liquid crystal layer include a liquid crystal composition containing a polymerizable liquid crystal compound and a chiral agent (optically active compound). If necessary, apply the above liquid crystal composition mixed with a surfactant or a polymerization initiator and dissolved in a solvent to the support, alignment layer, cholesteric liquid crystal layer as a lower layer, etc. A cholesteric liquid crystal layer can be formed by being fixed by curing the liquid crystal composition.

(Polymerizable liquid crystal compound)
The polymerizable liquid crystal compound may be a rod-like liquid crystal compound or a disk-like liquid crystal compound, but is preferably a rod-like liquid crystal compound.
Examples of the rod-like polymerizable liquid crystal compound forming the cholesteric liquid crystal layer include a rod-like nematic liquid crystal compound. Examples of rod-like nematic liquid crystal compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. Not only low-molecular liquid crystal compounds but also high-molecular liquid crystal compounds can be used.

The polymerizable liquid crystal compound can be obtained by introducing a polymerizable group into the liquid crystal compound. Examples of the polymerizable group include an unsaturated polymerizable group, an epoxy group, and an aziridinyl group, preferably an unsaturated polymerizable group, and particularly preferably an ethylenically unsaturated polymerizable group. The polymerizable group can be introduced into the molecule of the liquid crystal compound by various methods. The number of polymerizable groups contained in the polymerizable liquid crystal compound is preferably 1 to 6, more preferably 1 to 3 in one molecule. Examples of polymerizable liquid crystal compounds are described in Makromol. Chem. 190, 2255 (1989), Advanced Materials, 5, 107 (1993), US Pat. No. 4,683,327, US Pat. No. 5,622,648, US Pat. No. 5,770,107, International Publication WO95 / 22586, International Publications WO95 / 24455, WO97 / 00600, WO98 / 23580, WO98 / 52905, JP-A-1-272551, JP-A-6-16616, JP-A-7-110469, JP-A-11-80081. And the compounds described in JP-A No. 2001-328973 and the like. Two or more kinds of polymerizable liquid crystal compounds may be used in combination. When two or more kinds of polymerizable liquid crystal compounds are used in combination, the alignment temperature can be lowered.

The addition amount of the polymerizable liquid crystal compound in the liquid crystal composition is preferably 80 to 99.9% by mass with respect to the solid content mass (mass excluding the solvent) of the liquid crystal composition, and is preferably 85 to 99. It is more preferably 5% by mass, particularly preferably 90 to 99% by mass.

(Low Δn polymerizable liquid crystal compound)
As can be seen from the above formula for the half-value width Δλ of the selective reflection band exhibiting selective reflection, a narrow band is obtained by forming a cholesteric liquid crystal phase using a low Δn polymerizable liquid crystal compound and fixing it to a film. A selective reflection layer can be obtained. Examples of the low Δn polymerizable liquid crystal compound include compounds described in International Publications WO2015 / 115390, WO2015 / 147243, WO2016 / 035873, JP2015-163596, and JP2016-53149A. The description of WO2016 / 047648 can also be referred to for the liquid crystal composition providing a selective reflection layer having a small half width.

The liquid crystal compound is also preferably a polymerizable compound represented by the following formula (I) described in WO2016 / 047648.

Where
A represents a phenylene group which may have a substituent or a trans-1,4-cyclohexylene group which may have a substituent,
L is a single bond, —CH ₂ O—, —OCH ₂ —, — (CH ₂ ) ₂ OC (═O) —, —C (═O) O (CH ₂ ) ₂ —, —C (═O) O Selected from the group consisting of —, —OC (═O) —, —OC (═O) O—, —CH═CH—C (═O) O—, and —OC (═O) —CH═CH—. A linking group
m represents an integer of 3 to 12,
Sp ¹ and Sp ² are each independently one or more of a single bond, a linear or branched alkylene group having 1 to 20 carbon atoms, and a linear or branched alkylene group having 1 to 20 carbon atoms. CH ₂ — is —O—, —S—, —NH—, —N (CH ₃ ) —, —C (═O) —, —OC (═O) —, or —C (═O) O—. A linking group selected from the group consisting of substituted groups;
Q ¹ and Q ² each independently represent a hydrogen atom or a polymerizable group selected from the group consisting of groups represented by the following formulas Q-1 to Q-5, provided that any ^one of Q ¹ and Q ² One of them represents a polymerizable group. In formulas Q-1 to Q-5, * represents a bonding position.

In the formula (I), the phenylene group is preferably a 1,4-phenylene group.
The substituent when “optionally substituted” for the phenylene group and the trans-1,4-cyclohexylene group is not particularly limited, and examples thereof include an alkyl group, a cycloalkyl group, an alkoxy group, and an alkyl ether. And a substituent selected from the group consisting of a group composed of a group, an amide group, an amino group, a halogen atom, and two or more of the above substituents. Examples of the substituent include a substituent represented by -C (= O) -X ³ -Sp ³ -Q ³ described later. The phenylene group and trans-1,4-cyclohexylene group may have 1 to 4 substituents. When it has two or more substituents, the two or more substituents may be the same or different from each other.

In the present specification, the alkyl group may be linear or branched. The alkyl group preferably has 1 to 30 carbon atoms, more preferably 1 to 10 carbon atoms, and particularly preferably 1 to 6 carbon atoms. Examples of the alkyl group include, for example, methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group. And a 1,1-dimethylpropyl group, n-hexyl group, isohexyl group, linear or branched heptyl group, octyl group, nonyl group, decyl group, undecyl group, or dodecyl group. The above description regarding the alkyl group is the same for the alkoxy group containing an alkyl group. In the present specification, specific examples of the alkylene group referred to as an alkylene group include a divalent group obtained by removing one arbitrary hydrogen atom in each of the above examples of the alkyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

In the present specification, the cycloalkyl group preferably has 3 to 20 carbon atoms, more preferably 5 or more, more preferably 10 or less, still more preferably 8 or less, and still more preferably 6 or less. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group.

The substituents that the phenylene group and the trans-1,4-cyclohexylene group may have are particularly an alkyl group, an alkoxy group, and a group consisting of —C (═O) —X ³ —Sp ³ —Q ³ Substituents selected from are preferred. Here, X ³ represents a single bond, —O—, —S—, or —N (Sp ⁴ -Q ⁴ ) —, or represents a nitrogen atom that forms a ring structure with Q ³ and Sp ^3. Show. Sp ³ and Sp ⁴ are each independently one or more of a single bond, a linear or branched alkylene group having 1 to 20 carbon atoms, and a linear or branched alkylene group having 1 to 20 carbon atoms. CH ₂ — is —O—, —S—, —NH—, —N (CH ₃ ) —, —C (═O) —, —OC (═O) —, or —C (═O) O—. A linking group selected from the group consisting of substituted groups is shown.

Q ³ and Q ⁴ are each independently a hydrogen atom, a cycloalkyl group, or a cycloalkyl group, wherein one or more —CH ₂ — is —O—, —S—, —NH—, —N (CH ₃ ) —, —C (═O) —, —OC (═O) —, or a group substituted with —C (═O) O—, or a group represented by Formulas Q-1 to Q-5 Any polymerizable group selected from the group consisting of:

In the cycloalkyl group, one or more of —CH ₂ — is —O—, —S—, —NH—, —N (CH ₃ ) —, —C (═O) —, —OC (═O). Specific examples of the group substituted with — or —C (═O) O— include a tetrahydrofuranyl group, a pyrrolidinyl group, an imidazolidinyl group, a pyrazolidinyl group, a piperidyl group, a piperazinyl group, and a morpholinyl group. The substitution position is not particularly limited. Of these, tetrahydrofuranyl group is preferable, and 2-tetrahydrofuranyl group is particularly preferable.

In the formula (I), L represents a single bond, —CH ₂ O—, —OCH ₂ —, — (CH ₂ ) ₂ OC (═O) —, —C (═O) O (CH ₂ ) ₂ —, — C (═O) O—, —OC (═O) —, —OC (═O) O—, —CH═CH—C (═O) O—, —OC (═O) —CH═CH—, A linking group selected from the group consisting of: L is preferably —C (═O) O— or —OC (═O) —. The m-1 Ls may be the same as or different from each other.

Sp ¹ and Sp ² are each independently one or more of a single bond, a linear or branched alkylene group having 1 to 20 carbon atoms, and a linear or branched alkylene group having 1 to 20 carbon atoms. CH ₂ — is —O—, —S—, —NH—, —N (CH ₃ ) —, —C (═O) —, —OC (═O) —, or —C (═O) O—. A linking group selected from the group consisting of substituted groups is shown. Sp ¹ and Sp ² each independently has 1 carbon atom to which a linking group selected from the group consisting of —O—, —OC (═O) —, and —C (═O) O— is bonded to both ends. A group selected from the group consisting of 1 to 10 linear alkylene groups, —OC (═O) —, —C (═O) O—, —O—, and linear alkylene groups having 1 to 10 carbon atoms. Is preferably a linking group composed of one or more of them, and is preferably a linear alkylene group having 1 to 10 carbon atoms having —O— bonded to both ends.

Q ¹ and Q ² each independently represent a hydrogen atom or a polymerizable group selected from the group consisting of groups represented by the above formulas Q-1 to Q-5, provided that Q ¹ and Q ² Either one represents a polymerizable group.
As the polymerizable group, an acryloyl group (formula Q-1) or a methacryloyl group (formula Q-2) is preferable.

In the formula (I), m represents an integer of 3 to 12, preferably an integer of 3 to 9, more preferably an integer of 3 to 7, and further preferably an integer of 3 to 5. .

The polymerizable compound represented by the formula (I) has at least one phenylene group which may have a substituent as A and a trans-1,4-cyclohexylene group which may have a substituent. It is preferable to include at least one. The polymerizable compound represented by the formula (I) preferably contains 1 to 4 trans-1,4-cyclohexylene groups which may have a substituent as A, and preferably 1 to 3 Is more preferable, and it is more preferable that 2 or 3 is included. In the polymerizable compound represented by the formula (I), A preferably contains at least one phenylene group which may have a substituent, more preferably 1 to 4, more preferably 1 to 1. It is more preferable to include three, and it is particularly preferable to include two or three.

In the formula (I), when mc is a number obtained by dividing the number of trans-1,4-cyclohexylene groups represented by A by m, 0.1 <mc <0.9 is preferably satisfied. More preferably, 3 <mc <0.8, and even more preferably 0.5 <mc <0.7. Polymeric compound represented by formula (I) where 0.1 <mc <0.3, together with polymerizable compound represented by formula (I) where the liquid crystal composition is 0.5 <mc <0.7 It is also preferable to contain.

Specific examples of the polymerizable compound represented by the formula (I) include, in addition to the compounds described in paragraphs 0051 to 0058 of WO2016 / 047648, JP2013-112163A, JP2010-70543A, Examples thereof include compounds described in Japanese Patent No. 4725516, International Publication Nos. WO2015 / 115390, WO2015 / 147243, WO2016 / 035873, JP2015-163596A, and JP2016-53149A.

(Chiral agent: optically active compound)
The chiral agent has a function of inducing a helical structure of a cholesteric liquid crystal phase. The chiral compound may be selected according to the purpose because the helical sense or helical pitch induced by the compound is different.
There is no restriction | limiting in particular as a chiral agent, A well-known compound can be used. Examples of chiral agents include liquid crystal device handbook (Chapter 3, Section 4-3, TN, chiral agent for STN, 199 pages, edited by Japan Society for the Promotion of Science, 142th Committee, 1989), JP-A 2003-287623, Examples thereof include compounds described in JP-A No. 2002-302487, JP-A No. 2002-80478, JP-A No. 2002-80851, JP-A No. 2010-181852 or JP-A No. 2014-034581.

A chiral agent generally contains an asymmetric carbon atom, but an axially asymmetric compound or a planar asymmetric compound containing no asymmetric carbon atom can also be used as the chiral agent. Examples of the axial asymmetric compound or the planar asymmetric compound include binaphthyl, helicene, paracyclophane, and derivatives thereof. The chiral agent may have a polymerizable group. When both the chiral agent and the liquid crystal compound have a polymerizable group, they are derived from the repeating unit derived from the polymerizable liquid crystal compound and the chiral agent by a polymerization reaction between the polymerizable chiral agent and the polymerizable liquid crystal compound. A polymer having repeating units can be formed. In this aspect, the polymerizable group possessed by the polymerizable chiral agent is preferably the same group as the polymerizable group possessed by the polymerizable liquid crystal compound. Therefore, the polymerizable group of the chiral agent is also preferably an unsaturated polymerizable group, an epoxy group or an aziridinyl group, more preferably an unsaturated polymerizable group, and an ethylenically unsaturated polymerizable group. Particularly preferred.
The chiral agent may be a liquid crystal compound.

As the chiral agent, an isosorbide derivative, an isomannide derivative, or a binaphthyl derivative can be preferably used. As the isosorbide derivative, a commercial product such as LC-756 manufactured by BASF may be used.
The content of the chiral agent in the liquid crystal composition is preferably 0.01 mol% to 200 mol%, more preferably 1 mol% to 30 mol%, based on the amount of the polymerizable liquid crystal compound.

(Polymerization initiator)
The liquid crystal composition preferably contains a polymerization initiator. In the embodiment in which the polymerization reaction is advanced by ultraviolet irradiation, the polymerization initiator to be used is preferably a photopolymerization initiator that can start the polymerization reaction by ultraviolet irradiation. Examples of photopolymerization initiators include α-carbonyl compounds (described in US Pat. No. 2,367,661 and US Pat. No. 2,367,670), acyloin ethers (described in US Pat. No. 2,448,828), α-hydrocarbons. A substituted aromatic acyloin compound (described in US Pat. No. 2,722,512), a polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a triarylimidazole dimer and p-aminophenylketone Combination (described in U.S. Pat. No. 3,549,367), acridine and phenazine compound (JP-A-60-105667, U.S. Pat. No. 4,239,850), acylphosphine oxide compound (JP-B 63-40799), Japanese Patent Publication No. 5-29234, JP 10 JP-A-95788, JP-A-10-29997, JP-A-2001-233842, JP-A-2000-80068, JP-A-2006-342166, JP-A-2013-114249, JP-A-2014-137466. , JP4223071, JP2010-262028, JP2014-500852), oxime compounds (JP2000-66385, Japanese Patent No. 4454667), and Oxazi Examples thereof include azole compounds (described in US Pat. No. 4,221,970). For example, the description in paragraphs 0500 to 0547 of JP2012-208494A can be considered.

As the polymerization initiator, it is also preferable to use an acyl phosphine oxide compound or an oxime compound.
As the acylphosphine oxide compound, for example, IRGACURE 810 (compound name: bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide) manufactured by BASF Japan Ltd. can be used. Examples of the oxime compounds include IRGACURE OXE01 (manufactured by BASF), IRGACURE OXE02 (manufactured by BASF), TR-PBG-304 (manufactured by Changzhou Strong Electronic New Materials Co., Ltd.), Adeka Arcles NCI-831, Adeka Arcles NCI-930 Commercial products such as (ADEKA) and Adeka Arcles NCI-831 (ADEKA) can be used.
Only one type of polymerization initiator may be used, or two or more types may be used in combination.
The content of the photopolymerization initiator in the liquid crystal composition is preferably 0.1% by mass to 20% by mass, and preferably 0.5% by mass to 5% by mass with respect to the content of the polymerizable liquid crystal compound. It is more preferable.

(Crosslinking agent)
The liquid crystal composition may optionally contain a crosslinking agent in order to improve the film strength after curing and improve the durability. As the cross-linking agent, one that can be cured by ultraviolet rays, heat, moisture, or the like can be suitably used.
There is no restriction | limiting in particular as a crosslinking agent, According to the objective, it can select suitably, For example, polyfunctional acrylate compounds, such as a trimethylol propane tri (meth) acrylate and pentaerythritol tri (meth) acrylate; Glycidyl (meth) acrylate , Epoxy compounds such as ethylene glycol diglycidyl ether; aziridine compounds such as 2,2-bishydroxymethylbutanol-tris [3- (1-aziridinyl) propionate], 4,4-bis (ethyleneiminocarbonylamino) diphenylmethane; hexa Isocyanate compounds such as methylene diisocyanate and biuret type isocyanate; polyoxazoline compounds having an oxazoline group in the side chain; vinyltrimethoxysilane, N- (2-aminoethyl) 3-aminopropylto Alkoxysilane compounds such as methoxy silane. Moreover, a well-known catalyst can be used according to the reactivity of a crosslinking agent, and productivity can be improved in addition to membrane strength and durability improvement. These may be used individually by 1 type and may use 2 or more types together.
The content of the crosslinking agent is preferably 3% by mass to 20% by mass, and more preferably 5% by mass to 15% by mass. By making the content of the crosslinking agent 3% by mass or more, the effect of improving the crosslinking density can be obtained, and by making the content of the crosslinking agent 20% by mass or less, the stability of the cholesteric liquid crystal layer is lowered. Can be prevented.

(Orientation control agent)
In the liquid crystal composition, an alignment control agent that contributes to stably or rapidly forming a cholesteric liquid crystal layer having a planar alignment may be added. Examples of the alignment control agent include fluorine (meth) acrylate polymers described in paragraphs [0018] to [0043] of JP-A-2007-272185, and paragraphs [0031] to [0034] of JP-A-2012-203237. And compounds represented by the formulas (I) to (IV) as described above.
In addition, as an orientation control agent, 1 type may be used independently and 2 or more types may be used together.

The addition amount of the alignment control agent in the liquid crystal composition is preferably 0.01% by mass to 10% by mass, more preferably 0.01% by mass to 5% by mass with respect to the total mass of the polymerizable liquid crystal compound. 0.02% by mass to 1% by mass is particularly preferable.

(Other additives)
In addition, the liquid crystal composition may contain at least one selected from various additives such as a surfactant for adjusting the surface tension of the coating film and making the thickness uniform, and a polymerizable monomer. In addition, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a light stabilizer, a colorant, metal oxide fine particles, etc. are added to the liquid crystal composition as necessary, as long as optical performance is not deteriorated. can do.

A cholesteric liquid crystal layer is prepared by preparing a liquid crystal composition in which a polymerizable liquid crystal compound and a polymerization initiator, a chiral agent added as necessary, a surfactant, and the like are dissolved in a solvent, a support, an alignment layer, or first. A cholesteric liquid crystal layer in which the cholesteric regularity is fixed by coating the cholesteric liquid crystal layer on the coated cholesteric liquid crystal layer and drying to obtain a coating film, and irradiating the coating film with actinic rays to polymerize the cholesteric liquid crystalline composition Can be formed. In addition, the laminated film which consists of a some cholesteric liquid crystal layer can be formed by repeating the said manufacturing process of a cholesteric liquid crystal layer.

(solvent)
There is no restriction | limiting in particular as a solvent used for preparation of a liquid-crystal composition, Although it can select suitably according to the objective, An organic solvent is used preferably.
The organic solvent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, ketones, alkyl halides, amides, sulfoxides, heterocyclic compounds, hydrocarbons, esters, ethers, etc. Is mentioned. These may be used individually by 1 type and may use 2 or more types together. Among these, ketones are particularly preferable in consideration of environmental load.

(Coating, orientation, polymerization)
The method for applying the liquid crystal composition to the support, the alignment layer, the underlying cholesteric liquid crystal layer, etc. is not particularly limited and can be appropriately selected according to the purpose. For example, a wire bar coating method, a curtain coating method, Examples include extrusion coating, direct gravure coating, reverse gravure coating, die coating, spin coating, dip coating, spray coating, and slide coating. It can also be carried out by transferring a liquid crystal composition separately coated on a support. The liquid crystal molecules are aligned by heating the applied liquid crystal composition. The heating temperature is preferably 200 ° C. or lower, and more preferably 130 ° C. or lower. By this alignment treatment, an optical thin film in which the polymerizable liquid crystal compound is twisted and aligned so as to have a helical axis in a direction substantially perpendicular to the film surface is obtained.

The liquid crystal composition can be cured by further polymerizing the aligned liquid crystal compound. The polymerization may be either thermal polymerization or photopolymerization utilizing light irradiation, but photopolymerization is preferred. It is preferable to use ultraviolet rays for light irradiation. The irradiation energy is preferably ^{20mJ / cm 2 ~ 50J / cm} 2, 100mJ / cm 2 ~ 1,500mJ / cm 2 is more preferable.
In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions or in a nitrogen atmosphere. The irradiation ultraviolet wavelength is preferably 350 nm to 430 nm. The polymerization reaction rate is preferably as high as possible from the viewpoint of stability, preferably 70% or more, and more preferably 80% or more. The polymerization reaction rate can be determined by measuring the consumption ratio of the polymerizable functional group using an IR absorption spectrum.

[Support, orientation layer, etc.]
The half mirror film or the circularly polarized light reflection layer may include other layers such as a support and an alignment layer. All other layers are preferably transparent in the visible light region. In this specification, being transparent in the visible light region means that the transmittance of visible light is 70% or more. Moreover, it is preferable that all other layers have low birefringence. In the present specification, low birefringence means that the front phase difference is 10 nm or less in the wavelength region where the projected image display portion of the windshield glass of the present invention shows reflection, and the front phase difference is It is preferable that it is 5 nm or less. Further, it is preferable that the other layers have a small difference in refractive index from the average refractive index (in-plane average refractive index) of the cholesteric liquid crystal layer.

The support can be a substrate when forming a cholesteric liquid crystal layer or a retardation layer described later. The support is not particularly limited. The support used for forming the cholesteric liquid crystal layer or retardation layer is a temporary support that is peeled off after the formation of the cholesteric liquid crystal layer, and may not be included in the finished half mirror film or windshield glass. Good. Examples of the support include plastic films such as polyester such as polyethylene terephthalate (PET), polycarbonate, acrylic resin, epoxy resin, polyurethane, polyamide, polyolefin, cellulose derivative, and silicone. In addition to the plastic film, glass may be used as the temporary support.
The thickness of the support may be about 5.0 μm to 1000 μm, preferably 10 μm to 250 μm, and more preferably 15 μm to 100 μm.

The half mirror film may include an alignment layer as a lower layer to which the liquid crystal composition is applied when forming the cholesteric liquid crystal layer or the retardation layer.
The alignment layer has a rubbing treatment of organic compounds such as polymers (resins such as polyimide, polyvinyl alcohol, polyester, polyarylate, polyamideimide, polyetherimide, polyamide, modified polyamide), oblique deposition of inorganic compounds, and microgrooves. It can be provided by means such as formation of a layer or accumulation of an organic compound (for example, ω-tricosanoic acid, dioctadecylmethylammonium chloride, methyl stearylate) using the Langmuir-Blodgett method (LB film). Further, an alignment layer that generates an alignment function by application of an electric field, application of a magnetic field, or light irradiation may be used.
In particular, the alignment layer made of a polymer is preferably subjected to a rubbing treatment and then a liquid crystal composition is applied to the rubbing treatment surface. The rubbing treatment can be performed by rubbing the surface of the polymer layer with paper or cloth in a certain direction.
You may apply | coat a liquid-crystal composition to the surface of a support body which does not provide an alignment layer, or the surface which carried out the rubbing process of the support body.
In the case of forming a liquid crystal layer using a temporary support, the alignment layer may not be peeled off together with the temporary support to form a half mirror film.
The thickness of the alignment layer is preferably 0.01 μm to 5.0 μm, and more preferably 0.05 μm to 2.0 μm.

<Base material>
The windshield glass of the present invention includes a substrate. The base material is adjacent to the half mirror film in the windshield glass including the first glass plate, the first resin film, the half mirror film, the second resin film, and the second glass plate in this order. Adjacent to the half mirror film means that the first glass plate, the first resin film, the substrate, the half mirror film, the second resin film, and the second glass plate are in this order, or The base material is included in the windshield glass so that the first glass plate, the first resin film, the half mirror film, the base material, the second resin film, and the second glass plate are in this order. Means that. For example, the half mirror film may be in direct contact with the base material or bonded to the base material via an adhesive layer. The base material may be adjacent to the half mirror film on the entire main surface, or may be adjacent to the half mirror film on a part of the main surface. Further, the substrate may have substantially the same shape and area as the glass plate, or may have a smaller area than the glass plate. Preferably, the substrate has substantially the same shape and area as the glass plate, and the half mirror film may be adjacent to the substrate at a part of the main surface of the substrate. By making the base material approximately the same shape and area as the glass plate, the level difference when sandwiching the laminated film including the base material and the half mirror film between the resin films is reduced as will be described later, and air bubbles are lost when making laminated glass. Problems such as difficulty are unlikely to occur. The half mirror film is preferably bonded to a part of the main surface of the base material via an adhesive layer.

The base material has an elastic modulus of 3 GPa to 10 GPa and a thickness of 150 μm to 500 μm. By using a base material having such an elastic modulus and thickness, the above-mentioned orange peel problem can be reduced. The elastic modulus of the substrate is preferably 3.5 GPa to 9 GPa, more preferably 4 GPa to 8 GPa. The thickness of the substrate is preferably 160 μm to 400 μm, and more preferably 170 μm to 300 μm.
The base material preferably has an elastic modulus of 5 GPa to 8 GPa and a thickness of 170 μm to 300 μm.

In this specification, the elastic modulus is determined by pulling the sample at a speed of 10 mm / min using a tensile tester in accordance with the measurement method of JIS K7127, and obtaining the strength and elongation when the sample is cut, thereby deforming the sample. Measured from the maximum elasticity immediately before (primary expression of the tangent of the maximum slope of the SS curve).

Examples of the substrate include plastic films such as polyester such as polyethylene terephthalate (PET), polycarbonate, acrylic resin, epoxy resin, polyurethane, polyamide, polyolefin, cellulose derivative, and silicone. Among these, a polyethylene terephthalate film is preferable from the viewpoint of cost. As the polyethylene terephthalate film, a film having a low haze, a high transmittance, and a film that is difficult to hydrolyze is preferable. The thickness of the polyethylene terephthalate film is more preferably 170 μm to 300 μm.
A retardation layer (a first retardation layer or a second retardation layer) described later may also serve as a base material.

<Laminated film including base material and half mirror film>
It is preferable that the base material and the half mirror film are integrated before the process of manufacturing the laminated glass described later and are a laminated film including the base material and the half mirror film. The orange peel-like unevenness in the half mirror film in the windshield glass is obtained by integrating the base material having the elastic modulus and thickness and the half mirror film before the process including the heating and pressurizing processes. Can be prevented. The aspects of the base material and the half mirror film in the laminated film are the same as those described in the above-described windshield glass.

Integrating may be performed by directly forming a half mirror film on the substrate, or may be performed by bonding both, but it is preferable to bond both. Bonding may be performed by an adhesive layer described later. At this time, the thickness of the adhesive layer is preferably 10 μm or less. This is because, by setting the thickness of the adhesive layer to 10 μm or less, orange-peel-shaped unevenness derived from the adhesive layer is unlikely to occur. Among the adhesive layers to be described later, it is preferable to use an ultraviolet curing type as an adhesive for adhering the base material and the half mirror film. In general, an ultraviolet curable adhesive has a sufficient adhesive strength with a thickness of 10 μm or less, and therefore, an ultraviolet curable adhesive is used to provide an adhesive layer of 10 μm or less, preferably 5 μm or less, more preferably 3 μm or less. be able to. As a highly transparent adhesive transfer tape (OCA tape) described later, a commercially available product generally has a thickness exceeding 10 μm, and therefore, a tape having a thickness of 10 μm or less may be selected and used.

In the half mirror film including the support, the support may be peeled off simultaneously with the adhesion to the substrate, immediately after, or immediately before.
In the laminated film, the half mirror film is preferably bonded to a part of the main surface of the base material via an adhesive layer. When it is a part, the area may be 90% or less, 50% or less, 40% or less, 30% or less, 20% or less, 10% or less, 5% or less, etc. with respect to the total area of the substrate. It may be 1% or more, 3% or more, 5% or more, 7% or more, 10% or more. At this time, it is preferable that the base material has substantially the same shape and area as the windshield glass to be manufactured.

<Phase difference layer>
The windshield glass of the present invention may include a retardation layer between the circularly polarized light reflecting layer and the second resin film. A clear projected image can be displayed by using a retardation layer in which the front retardation is appropriately adjusted in combination with the circularly polarized light reflecting layer.
In the windshield glass of the present invention, the retardation layer may be included as a layer constituting the half mirror film, or may be included as a base material.

There is no restriction | limiting in particular as a phase difference layer, According to the objective, it can select suitably.
Examples of retardation layers, particularly preferred examples of retardation layers contained in windshield glass as a substrate include stretched polycarbonate films, stretched norbornene polymer films, and inorganic having birefringence such as strontium carbonate. Examples thereof include a transparent film containing particles and oriented, a thin film obtained by obliquely depositing an inorganic dielectric on a support, and a film obtained by orienting and fixing a liquid crystal compound uniaxially.

As an example of the retardation layer, a preferable example of the retardation layer included as a layer constituting the half mirror film is a film in which a polymerizable liquid crystal compound is uniaxially aligned and fixed. For example, for the retardation layer, a liquid crystal composition containing a polymerizable liquid crystal compound is applied to the surface of the support or the alignment layer, and the polymerizable liquid crystal compound in the liquid crystal composition is formed in a nematic alignment in a liquid crystal state and then fixed by curing. Can be formed. In this case, the retardation layer can be formed in the same manner as the formation of the cholesteric liquid crystal layer except that no chiral agent is added to the liquid crystal composition. However, the heating temperature is preferably 50 ° C. to 120 ° C. and more preferably 60 ° C. to 100 ° C. in the nematic alignment after the application of the liquid crystal composition.

A retardation layer, particularly a retardation layer included as a part of a half mirror film, is formed by applying a composition containing a polymer liquid crystal compound on the surface of a support or an alignment layer to form a nematic alignment in a liquid crystal state. Further, it may be a layer obtained by fixing the orientation by cooling.

The thickness of the retardation layer included as a layer constituting the half mirror film is not particularly limited, but is preferably 0.2 μm to 10 μm, more preferably 0.5 μm to 5.0 μm, and 1.0 μm to 2. 0 μm is more preferable.

The retardation layer is particularly preferably a λ / 2 retardation layer. The projected image display part produced by combining the λ / 2 retardation layer and the circularly polarized reflective layer is compared with, for example, the projected image display part using a combination of the λ / 4 retardation layer and the circularly polarized reflective layer. Thus, higher luminance can be given and double images can be prevented.

The front phase difference of the λ / 2 retardation layer may be a length that is ½ of the visible light wavelength region, or “center wavelength × n ± ½ of the center wavelength (n is an integer)”. In particular, the reflection wavelength of the circularly polarized light reflection layer (for example, any cholesteric liquid crystal) or the length of ½ of the center wavelength of the light emission wavelength of the light source may be used. For example, the phase difference may be in the range of 190 nm to 390 nm, and the phase difference is preferably in the range of 200 nm to 350 nm.

The slow axis direction of the λ / 2 retardation layer can be determined according to the incident direction of incident light for projected image display and the spiral sense of the cholesteric liquid crystal layer when used as a head-up display system. preferable. For example, the incident light is in the lower (vertically lower) direction of the projected image display portion and may be referred to as “λ / 2 phase difference layer side” (in this specification, “from the observer side”) with respect to the circularly polarized light reflection layer ) When incident, it is preferable that the slow axis of the λ / 2 retardation layer is in the range of + 40 ° to + 65 ° or −40 ° to −65 ° with respect to the vertical upward direction of the projected image display portion. Further, the slow axis direction is preferably set as follows according to the spiral sense of the cholesteric liquid crystal layer in the circularly polarized light reflecting layer. When the sense is on the right (preferably, when the senses of all cholesteric liquid crystal layers are on the right), the slow axis of the λ / 2 retardation layer is viewed from the observer side with respect to the vertical upward direction of the projected image display region. In the clockwise direction, it is preferably in the range of 40 ° to 65 °, preferably 45 ° to 60 °. When the sense is on the left (preferably, the sense of all cholesteric liquid crystal layers is on the left), the slow axis of the λ / 2 retardation layer is viewed from the observer side with respect to the vertical upward direction of the projected image display area. Thus, it is preferably in the range of 40 ° to 65 °, preferably 45 ° to 60 ° counterclockwise.

<Second retardation layer>
The windshield glass of the present invention may include a second retardation layer in addition to the retardation layer. Hereinafter, for the purpose of distinction, the retardation layer included between the circularly polarized light reflection layer and the second resin film may be referred to as a first retardation layer. The second retardation layer may be provided so that the first retardation layer (preferably λ / 2 retardation layer), the circularly polarized light reflection layer, and the second retardation layer are in this order. In particular, the first retardation layer, the circularly polarized light reflection layer, and the second retardation layer may be provided in this order from the viewer side. The second retardation layer may be included as a part of the half mirror film or may be included as a base material.

By including the second retardation layer, double images can be further prevented. In particular, it is possible to further prevent double images when a projected image is formed by entering p-polarized light. The effect is more remarkable when a low Δn polymerizable liquid crystal compound is used for forming a cholesteric liquid crystal layer in the circularly polarized light reflection layer.
The reason that the double image can be further prevented by using the second retardation layer is that light having a wavelength not in the selective reflection band of the cholesteric liquid crystal layer included in the circularly polarized light reflection layer is polarized and converted by the cholesteric liquid crystal layer. It is presumed that the double image generated based on the reflection on the back surface of the windshield glass can be prevented.

The retardation of the second retardation layer may be appropriately adjusted in the range of 160 nm to 460 nm, preferably in the range of 240 nm to 420 nm at the wavelength of 550 nm.
The material, thickness, and the like of the second retardation layer can be selected in the same range as the first retardation layer.

It is preferable that the slow axis direction of the second retardation layer is determined according to the incident direction of incident light for projecting image display and the spiral sense of the cholesteric liquid crystal layer. For example, the second phase difference layer having a phase difference in the range of 160 nm to 400 nm at a wavelength of 550 nm is + 10 ° to + 35 ° or −10 ° to −35 ° with respect to the vertical direction of the projected image display portion. It is preferable to be in the range. Alternatively, the slow axis of the second retardation layer having a phase difference in the range of 200 nm to 400 nm at the wavelength of 550 nm is + 100 ° to + 140 ° or −100 ° to −140 ° with respect to the vertical upward direction of the projected image display portion. It is preferable to be in the range.

<Adhesive layer>
The adhesive layer is not only between the base material and the half mirror film as described above, but also, for example, between the cholesteric liquid crystal layer, between the circularly polarized reflective layer and the first retardation layer, and between the circularly polarized reflective layer and the second retardation. It may be provided between layers. Further, it may be provided between the half mirror film and the resin film, between the base material and the resin film, or the like.
The adhesive layer is preferably transparent in the visible light region. The adhesive layer preferably has low birefringence, and preferably has a small difference in refractive index from the average refractive index (in-plane average refractive index) of the cholesteric liquid crystal layer.

As the adhesive layer, one formed from an adhesive can be used.
Adhesives include hot melt type, thermosetting type, photocuring type, reactive curing type, and pressure-sensitive adhesive type that does not require curing, from the viewpoint of curing method, and the materials are acrylate, urethane, urethane acrylate, epoxy , Epoxy acrylate, polyolefin, modified olefin, polypropylene, ethylene vinyl alcohol, vinyl chloride, chloroprene rubber, cyanoacrylate, polyamide, polyimide, polystyrene, polyvinyl butyral, etc. can do. From the viewpoint of workability and productivity, the photo-curing type, particularly the ultraviolet curing type, is preferable as the curing method, and from the viewpoint of optical transparency and heat resistance, the material is acrylate, urethane acrylate, epoxy acrylate, etc. It is preferable to do.

The thickness of the adhesive layer in the above example is preferably 0.5 μm to 10 μm, and more preferably 1.0 μm to 5.0 μm. In order to reduce color unevenness and the like of the projected image display part, it is preferable to provide the uniform thickness.

The adhesive layer may be formed using a highly transparent adhesive transfer tape (OCA tape). As the highly transparent adhesive transfer tape, a commercially available product for an image display device, particularly a commercially available product for the surface of the image display unit of the image display device can be used. Examples of commercially available products include PANAC Corporation pressure-sensitive adhesive sheets (PD-S1 and the like), MHI Series MHM series pressure-sensitive adhesive sheets, and the like.
The thickness of the OCA tape may be 1.0 μm to 50 μm, and preferably 2.0 μm to 30 μm. As described above, when used as an adhesive layer between the substrate and the half mirror film, the thickness of the OCA tape is preferably 10 μm or less.

<Laminated glass (manufacturing method of windshield glass)>
The windshield glass can be manufactured using a known laminated glass manufacturing method.
For example, in a laminate obtained by sandwiching two resin films in a state where a laminate film (hereinafter sometimes referred to as a laminate film) including a base material and a half mirror film is sandwiched between two glass plates On the other hand, it can be manufactured by performing pre-bonding and main-bonding. Alternatively, an intermediate film sheet having a structure in which a laminated film is sandwiched between two resin films is prepared in advance, and pre-compression and main pressure bonding are performed on a laminate obtained by sandwiching the intermediate film between two glass plates. It can be manufactured by doing.

The heating and pressurization at the time of forming the intermediate film having a structure in which the above laminated film is sandwiched between two resin films are, for example, a temperature of 40 ° C. or higher and 140 ° C. or lower, preferably a temperature of 60 ° C. or higher and 120 ° C. or lower, a pressure of 0.05 MPa It may be performed at 0.8 MPa or less and preferably at 0.1 MPa or more and 0.5 MPa or less.

Pre-crimping is a process performed for deaeration between layers in the production of laminated glass. The pre-compression is performed, for example, by putting the laminated body in a rubber bag connected to an exhaust system. The pressure at this time is preferably 100 kPa or less, more preferably 1 to 36 kPa. The pre-bonding can be performed by holding at a temperature of 70 ° C. to 130 ° C. for 10 minutes to 90 minutes.

Preliminary pressure bonding can be achieved by setting the holding temperature to 70 ° C. or higher. In addition, since the heat shrinkage of the half mirror film or the substrate is prevented from excessively proceeding by setting the holding temperature to 130 ° C. or less, the occurrence of cracks in the half mirror film or the substrate can be suppressed. The holding temperature is preferably 80 ° C. or higher, and more preferably 90 ° C. or higher. This is for performing deaeration more reliably. Further, the holding temperature is preferably 120 ° C. or lower, and more preferably 110 ° C. or lower.

If the holding time is 10 minutes or more, the preliminary pressure bonding can be sufficiently performed. On the other hand, when the holding time is 90 minutes or less, the productivity is good and the thermal shrinkage of the half mirror film or the base material can be prevented from proceeding excessively, thereby suppressing the occurrence of cracks in the half mirror film or the base material. be able to. The holding time is preferably 20 minutes or longer and 60 minutes or shorter from the viewpoint of more effectively and efficiently performing preliminary pressure bonding.

The main pressure bonding is performed in order to sufficiently bond the respective layers with the resin film. For example, a pre-pressure bonded body obtained by the pre-pressure bonding is put in an autoclave, the temperature is 110 ° C. or higher and 150 ° C. or lower, and the pressure is 0.98 MPa. This can be performed at a pressure of 1.47 MPa or less. More preferably, the temperature is 130 ° C. to 140 ° C. and the pressure is 1.1 MPa to 1.4 MPa. And it is preferable that it is 15 minutes or more and 90 minutes or less, and, as for the time (holding time) hold | maintained at the said temperature and pressure, it is more preferable that they are 30 minutes or more and 75 minutes or less.

By performing the main pressure bonding under the above conditions of holding temperature, holding pressure, or holding time, the occurrence of cracks in the half mirror film can be suppressed, and productivity and the like are also excellent.

<Layer on the viewing side with respect to the circularly polarized reflective layer>
In general, in a projection image display member, based on an image based on reflected light from a layer that reflects projection light, and reflection light from a front surface or a back side as viewed from the light incident side of the projection image display member. Double images (or multiple images) are caused by overlapping images. In the windshield glass of the present invention, the light transmitted through the cholesteric liquid crystal layer in the circularly polarized light reflection layer is circularly polarized light having a sense opposite to that of the circularly polarized light reflected by the cholesteric liquid crystal layer, and reflected light from the back side surface. If the layer on the back side of the circularly polarized light reflecting layer has low birefringence, the circularly polarized light that is usually reflected by the cholesteric liquid crystal layer is mostly, so that it is difficult to produce a noticeable double image. In particular, by using polarized light as the projection light, most of the projection light can be reflected by the circularly polarized light reflection layer. On the other hand, the reflected light from the front surface can cause a noticeable double image. In particular, if the distance from the center of gravity of the cholesteric liquid crystal layer to the front surface when viewed from the light incident side of the windshield glass is a certain value or more, a double image can be prominent. Specifically, in the structure of the windshield glass of the present invention, the total thickness of the layers on the second glass plate side from the circularly polarized reflective layer, that is, the outermost surface on the second glass plate side of the circularly polarized reflective layer From the circularly polarizing reflective layer, the distance to the outermost surface of the windshield glass on the second glass plate side is 0.5 mm or more, a double image can be prominent, and 1 mm or more can be more prominent, It may become more prominent at 1.5 mm or more, and may be particularly noticeable at 2.0 mm or more. Examples of the layer on the viewer side from the circularly polarized light reflecting layer include a first retardation layer, a second resin film, and a second glass plate.
However, the windshield glass of the present invention has a remarkable double effect even when the total thickness of the layers closer to the viewing side than the circularly polarized reflective layer is as described above in the projected image display using p-polarized light as described later. The projected image can be viewed without an image.

<< Head-up display system >>
The windshield glass of the present invention can be used as a component of a head-up display system. The head-up display system includes a projector. In the head-up display system, the substrate, the half mirror film, and the projector are preferably arranged in this order. When the windshield glass includes a retardation layer, the head-up display system preferably includes a circularly polarized light reflection layer, a retardation layer, and a projector arranged in this order.

<Projector>
In this specification, the “projector” is “an apparatus that projects light or an image”, and includes an “apparatus that projects a drawn image”. In the head-up display system of the present invention, the projector only needs to be arranged so as to be incident on the projected image display portion in the windshield glass at the oblique incident angle as described above.
In the head-up display system, the projector preferably includes a drawing device and reflects and displays an image (real image) drawn on a small intermediate image screen as a virtual image by a combiner.

[Drawing device]
The drawing device itself may be a device that displays an image, or may be a device that emits light capable of drawing an image. In the drawing device, the light from the light source may be adjusted by a drawing method such as an optical modulator, laser luminance modulation means, or light deflection means for drawing. In this specification, the drawing device means a device that includes a light source and further includes a light modulator, a laser luminance modulation unit, a light deflection unit for drawing, or the like according to a drawing method.

(light source)
The light source is not particularly limited, and LEDs (including light emitting diodes and organic light emitting diodes (OLED)), discharge tubes, laser light sources, and the like can be used. Of these, LEDs and discharge tubes are preferred. This is because it is suitable for a light source of a drawing device that emits linearly polarized light. Of these, LEDs are particularly preferred. This is because LEDs are suitable for combination with a combiner using a cholesteric liquid crystal layer exhibiting selective reflection in a specific wavelength region, as will be described later, because the emission wavelength is not continuous in the visible light region.

(Drawing method)
The drawing method can be selected according to the light source to be used and the application, and is not particularly limited.
Examples of the drawing method include a fluorescent display tube, a liquid crystal display (LCD) method using liquid crystal and a liquid crystal on silicon (LCOS) method, a DLP (digital light processing) method, and a scanning method using a laser. Etc. The drawing method may be a method using a fluorescent display tube integrated with a light source.

In the LCD method and the LCOS method, light of each color is modulated and combined by an optical modulator, and light is emitted from a projection lens.
The DLP system is a display system using DMD (Digital Micromirror Device), and is drawn by arranging micromirrors for the number of pixels, and light is emitted from a projection lens.
The scanning method is a method in which a light beam is scanned on a screen and an image is contrasted using an afterimage of an eye. For example, the descriptions in JP-A-7-270711 and JP-A-2013-228664 can be referred to. In the scanning method using laser, laser light of each color (for example, red light, green light, and blue light) whose luminance is modulated is bundled into one light beam by a multiplexing optical system or a condenser lens, and the light beam is light. It only needs to be scanned by the deflecting means and drawn on an intermediate image screen described later.
In the scanning method, the luminance modulation of laser light of each color (for example, red light, green light, and blue light) may be performed directly as a change in intensity of the light source, or may be performed by an external modulator. Examples of the light deflection means include a galvanometer mirror, a combination of a galvanometer mirror and a polygon mirror, or MEMS (microelectromechanical system). Among these, MEMS is preferable. Examples of the scanning method include a random scan method and a raster scan method, but it is preferable to use a raster scan method. In the raster scan method, the laser beam can be driven by a resonance frequency in the horizontal direction and a sawtooth wave in the vertical direction, for example. Since the scanning system does not require a projection lens, the apparatus can be easily downsized.

The light emitted from the drawing device may be linearly polarized light or natural light (non-polarized light). The light emitted from the drawing device included in the head-up display system of the present invention is preferably linearly polarized light. In a drawing device whose drawing method is LCD or LCOS and a drawing device using a laser light source, the emitted light is essentially linearly polarized light. When the output light is a linearly polarized light drawing device and the output light contains light of a plurality of wavelengths (colors), the polarization directions (transmission axis directions) of the plurality of light polarizations are the same or orthogonal to each other It is preferable. It is known that there are commercially available drawing devices whose polarization directions are not uniform in the wavelength range of red, green and blue light of the emitted light (see Japanese Patent Application Laid-Open No. 2000-212449). Specifically, an example in which the polarization direction of green light is orthogonal to the polarization direction of red light and the polarization direction of blue light is known.

(Intermediate image screen)
As described above, the drawing device may use an intermediate image screen. In this specification, an “intermediate image screen” is a screen on which an image is drawn. That is, when the light emitted from the drawing device is not yet visible as an image, the drawing device forms a visible image on the intermediate image screen by this light. The image drawn on the intermediate image screen may be projected onto the combiner by light transmitted through the intermediate image screen, or may be projected onto the combiner after reflecting off the intermediate image screen.

Examples of the intermediate image screen include a scattering film, a microlens array, and a screen for rear projection. When a plastic material is used as the intermediate image screen, if the intermediate image screen has birefringence, the polarization plane and light intensity of polarized light incident on the intermediate image screen are disturbed, and color unevenness is likely to occur in the combiner. However, the use of a retardation film having a predetermined phase difference can reduce the problem of color unevenness.
The intermediate image screen preferably has a function of spreading and transmitting incident light. This is because such a function makes it possible to display an enlarged projected image. As such an intermediate image screen, for example, a screen composed of a microlens array can be cited. The microarray lens used in the head-up display is described in, for example, Japanese Patent Application Laid-Open No. 2012-226303, Japanese Patent Application Laid-Open No. 2010-145745, and Japanese Patent Application Publication No. 2007-523369.
The projector may include a reflecting mirror that adjusts the optical path of the projection light formed by the drawing device.

With regard to a head-up display system using a windshield glass as a projection image display member, JP-A-2-141720, JP-A-10-96874, JP-A-2003-98470, US Pat. No. 5,013,134 are disclosed. Reference can be made to JP-T-2006-512622.

The windshield glass of the present invention is particularly useful for a head-up display system using a laser, LED, OLED or the like whose emission wavelength is not continuous in the visible light region in combination with a projector using a light source. This is because the central wavelength of selective reflection of the cholesteric liquid crystal layer can be adjusted according to each emission wavelength. Moreover, it can also be used for the projection of a display in which display light such as an LCD (Liquid Crystal Display) is polarized.

[Projection light (incident light)]
Incident light is preferably incident at an oblique incident angle of 45 ° to 70 ° with respect to the normal of the projected image display portion. As a method of reducing the double image that occurs when the projection light is reflected on the front or back surface of the glass, the projection light (p-polarized light) is incident on the glass surface at a Brewster angle, and the reflected light from the glass surface approaches zero. is there. (See, for example, JP-T-2006-512622). The Brewster angle at the interface between glass having a refractive index of about 1.51 and air having a refractive index of about 1 is about 56 °, and p-polarized light is incident within the above-mentioned angle range, so that incident light for displaying a projected image is displayed. The circularly polarized reflective layer has less reflected light from the surface of the λ / 2 retardation layer, and can display an image with less influence of a double image. The angle is preferably 50 ° to 65 °. At this time, the projected image is observed on the incident light plane side at an angle of 45 ° to 70 °, preferably 50 ° to 65 ° on the side opposite to the incident light with respect to the normal line of the λ / 2 retardation layer. Any configuration can be used.

When the half mirror film includes the first retardation layer, the incident light is incident on the circularly polarizing reflection layer from the first retardation layer side, and passes through the first retardation layer and then the circularly polarizing reflecting layer. It is sufficient to make it incident. That is, the first retardation layer may be disposed on the incident side of the projection light with respect to the circularly polarized light reflection layer. Further, the incident light may be incident from any direction such as up / down / left / right of the windshield glass, and may be determined according to the direction of the observer. For example, the incident light may be incident at an oblique incident angle as described above from the downward direction during use.
The slow axis of the first retardation layer (for example, λ / 2 retardation layer) in the windshield glass is 40 ° to 65 ° with respect to the vibration direction of the incident p-polarized light (incident light incident surface). An angle is preferable, and an angle of 45 ° to 60 ° is more preferable.

As described above, it is preferable that the projection light in the projection image display on the head-up display is p-polarized light that vibrates in a direction parallel to the incident surface. If the output light of the projector is not linearly polarized light, it may be p-polarized by using a linearly polarizing film arranged on the output light side of the projector, and it is made p-polarized in the optical path from the projector to the windshield glass. Also good. As described above, for projectors whose polarization directions in the red, green, and blue light wavelength ranges are not uniform, the polarization direction is adjusted in a wavelength-selective manner, and p-polarized light is used in all color wavelength ranges. It is preferable to make it enter.

The present invention will be described more specifically with reference to the following examples. The materials, reagents, amounts and ratios of substances, operations, and the like shown in the following examples can be appropriately changed without departing from the gist of the present invention. Therefore, the scope of the present invention is not limited to the following examples.

<Preparation of λ / 2 retardation layer>
The surface of Toyobo Co., Ltd. Cosmo Shine A-4100 (PET, thickness 75 μm) that has not been subjected to an easy adhesion treatment is rubbed, and the coating film 1 shown in Table 1 has a dry film thickness of 1.8 μm after drying. It applied at room temperature using a wire bar. In the coating solution 1 shown in Table 1, MEK (methyl ethyl ketone) was used as the solvent, and the amount of the solvent was adjusted so that the solid content concentration was 39% by mass. The coating layer was dried at room temperature for 30 seconds, then heated at 85 ° C. for 2 minutes, and then at 60 ° C. with a fusion D bulb (90 mW / cm lamp) at an output of 60% for 6 to 12 seconds with UV irradiation. Then, a liquid crystal layer was prepared, and a λ / 2 retardation layer with a PET base was obtained.

<Preparation of reflective layer UV (short wavelength cholesteric liquid crystal layer)>
On the λ / 2 phase difference layer, the coating liquid UV shown in Table 2 was applied at room temperature using a wire bar so that the dry film thickness after drying was 3 μm. In addition, in the coating liquid UV, the coating liquid B, the coating liquid G, and the coating liquid R shown in Table 2, an 8: 2 mixed liquid of methyl acetate and cyclohexanone is used as the solvent, and the solid content concentration becomes 25% by mass. Thus, the amount of solvent was adjusted. The coating layer was dried at room temperature for 30 seconds, then heated at 85 ° C. for 2 minutes, and then at 60 ° C. with a fusion D bulb (90 mW / cm lamp) at an output of 60% for 6 to 12 seconds with UV irradiation. Then, a liquid crystal layer was prepared to obtain a reflective layer UV with a PET base.

<Preparation of Reflective Layer B, Reflective Layer G, and Reflective Layer R>
The coating liquid B, the coating liquid G, and the coating liquid R shown in Table 2 were used in place of the coating liquid UV, respectively, and the thickness of the layer after drying on Cosmo Shine A-4100 (PET, thickness 75 μm) manufactured by Toyobo Co., Ltd. A reflective layer B, a reflective layer G, and a reflective layer R were produced in the same procedure as the production of the reflective layer UV, except that the thickness shown in Table 3 was applied using a wire bar at room temperature. .

Selective reflection center wavelength for incident light (normal incidence) from the normal direction and incident light inclined by 60 degrees from the normal direction with respect to the reflection layer surface of the obtained laminate, and sense of circular polarization of the reflected light It was confirmed. The center wavelength is measured using a spectrophotometer V-670 manufactured by JASCO, and the circularly polarized light sense of the circularly polarized light that is selectively reflected to the light receiving side of the spectrophotometer is known as the circularly polarized light sense of the reflected light. Was determined by measuring the reflected light intensity.
Moreover, the phase difference with respect to the light of wavelength 550nm of a (lambda) / 2 phase difference layer was measured in the following procedures. An OCA tape (MHM-UVC15 manufactured by Niei Kaiko Co., Ltd.) was bonded to an acrylic plate (thickness 0.2 mm, 40 mm square). The release film of the OCA tape was peeled off, and a λ / 2 retardation layer with a PET base was bonded onto the OCA tape on the surface on the λ / 2 retardation layer side. The PET was peeled off to produce a λ / 2 retardation layer with an acrylic plate. The retardation of the λ / 2 retardation layer with an acrylic plate was measured using an AxoScan manufactured by Axometrics, and was used as the retardation of the λ / 2 retardation layer.
The results are shown in Table 3.

<Preparation of half mirror film HM-1>
The reflection layer UV, the reflection layer B, the reflection layer G, and the reflection layer R layer are laminated in the order shown in Table 4 on the surface of the λ / 2 retardation layer side of the λ / 2 retardation layer with a PET base prepared in the same manner as described above. The half mirror film HM-1 was produced. Each layer is formed by applying a coating solution for forming each layer on the λ / 2 retardation layer or the reflective layer in the same manner as described above so that the thickness of the layer after drying becomes the thickness shown in Table 3. In the same manner as described above, drying and UV irradiation were performed.

<Preparation of laminated film of Example 1>
For Cosmo Shine A-4300 (PET, thickness 250 μm) manufactured by Toyobo Co., Ltd., the elastic modulus was measured according to the measurement method of JIS K 7127. A sample piece was cut out with a length of 10 mm in the longitudinal direction (MD) and a length of 150 mm in the width direction (TD) perpendicular to the MD, and a strograph R2 manufactured by Toyo Seiki Seisakusho was used for the sample piece. A tensile test was conducted. The tensile test was performed in the width direction of the sample piece with a distance between chucks of 100 mm and a tensile speed of 10 mm / min. As a result of the measurement, the elastic modulus was 4 GPa.

An adhesive layer (UVX-5457 manufactured by Toagosei Co., Ltd.) was applied to the PET film at room temperature using a wire bar so as to have a thickness of 5 μm. Next, the half mirror film produced above was bonded using a roller so that the reflective layer was on the PET film side. The PET that was the support for the retardation layer was peeled off. At this time, the slow axis direction of the retardation layer of the half mirror film HM-1 was referenced to the short side direction of the glass as viewed from the peeling surface. Were arranged so as to be in the direction of 60 ° in the clockwise direction. Thereafter, UV irradiation was performed at 60 ° C. with a fusion D bulb (lamp 90 mW / cm) at an output of 60% for 6 to 12 seconds to obtain a laminated film including a base material and a half mirror film. Further, this laminated film was cut into a length of 40 cm and a width of 25 cm.

<Production of Windshield Glass of Example 1>
Two glass plates having a thickness of 0.38 mm made by Sekisui Chemical Co., Ltd. prepared by cutting two glass plates having a length of 40 cm and a width of 25 cm and a thickness of 2 mm and the same shape as the glass plates were prepared. A glass plate, a PVB film, a laminated film of Example 1, a PVB film, and a glass plate were laminated so that the shapes overlap in this order.
Next, this laminate was held at 90 ° C. and 0.1 atm for 1 hour, and then heated at 115 ° C. and 13 atm for 20 minutes to remove bubbles, whereby the windshield glass of Example 1 was obtained. The layer structure of the obtained windshield glass is shown in FIG.

<Preparation of Windshield Glass of Examples 2 to 5 and Comparative Example 1>
The windows of Examples 2 to 5 and Comparative Example 1 were the same as the windshield glass of Example 1 except that the adhesive layer and the substrate were changed as shown in Table 5 or the formation region of the substrate and the half mirror film was changed. A shield glass was produced.
In Table 5, in the items of the area of the base material and the area of the half mirror film, “entire surface” is the same as that of Example 1, cut into the same shape as a 40 cm long and 25 cm wide glass plate, “partial” "" Cuts out into a shape of 20 cm in length and 10 cm in width and means installed at the center of the glass plate.

<Evaluation of orange peel>
The wind peel glass orange peel was evaluated indoors. The windshield glass was placed on a desk so that the base material of the laminated film was below the half mirror film, and the reflected image was visually evaluated by projecting a fluorescent lamp on the half mirror part. The evaluation criteria were as follows.
A: There is no distortion in the reflected image of the fluorescent lamp.
B: There is almost no distortion in the reflected image of the fluorescent lamp. When the viewpoint is shifted to the side, the reflected image fluctuates slightly. (Acceptable level)
C: The reflected image of the fluorescent lamp is blurred due to the fine wrinkles of the half mirror. (Acceptable level)
D: The reflected image of the fluorescent lamp appears distorted due to the large wrinkles of the half mirror.

<Evaluation of bubbles during crimping>
The evaluation of the bubbles in the windshield glass was performed visually. It was evaluated whether or not air bubbles remained at the end of the half mirror and were clouded.
The evaluation results are shown in Table 5.

1 Windshield glass 2 Glass plate 3 PVB film (resin film)
4 Half mirror film 5 Base material 6 Adhesive layer 7 Circularly polarized reflective layer 11 Reflective layer UV (cholesteric liquid crystal layer)
12 Reflective layer B (cholesteric liquid crystal layer)
13 Reflective layer G (Cholesteric liquid crystal layer)
14 Reflective layer R (cholesteric liquid crystal layer)
15 λ / 2 retardation layer (retardation layer)
21 Laminated film

Claims

A windshield glass including a first glass plate, a first resin film, a half mirror film, a second resin film, and a second glass plate in this order,
Further including a substrate,
The half mirror film includes a circularly polarized light reflection layer,
The circularly polarized light reflection layer includes a cholesteric liquid crystal layer;
The half mirror film is adjacent to the substrate;
A windshield glass in which the elastic modulus of the base material is 3 GPa to 10 GPa and the thickness of the base material is 150 μm to 500 μm.
The windshield glass according to claim 1, wherein the elastic modulus of the base material is 4 GPa to 8 GPa, and the thickness of the base material is 170 μm to 300 μm.
The windshield glass according to claim 1 or 2, wherein the half mirror film is bonded to the substrate by an adhesive layer.
The windshield glass according to claim 3, wherein the adhesive layer has a thickness of 0.5 袖 m to 10 袖 m.
The windshield glass according to any one of claims 1 to 4, wherein the half mirror film is adjacent to the base material at a part of a main surface of the base material.
The windshield glass according to any one of claims 1 to 5, comprising a retardation layer.
The windshield glass according to claim 6, wherein the retardation layer is a λ / 2 retardation layer.
The windshield glass according to claim 6 or 7, wherein the half mirror film includes the retardation layer.
The windshield glass according to claim 6 or 7, wherein the substrate is the retardation layer.
The windshield glass according to any one of claims 1 to 8, wherein the substrate is a polyethylene terephthalate film.
The circularly polarized light reflection layer includes three or more cholesteric liquid crystal layers having a central wavelength of selective reflection in the visible light region,
The windshield glass according to any one of claims 1 to 10, wherein the central wavelengths of selective reflection of each of the three or more cholesteric liquid crystal layers are different from each other.
including a λ / 2 retardation layer,
The circularly polarized light reflection layer includes four or more cholesteric liquid crystal layers;
One of the four or more cholesteric liquid crystal layers is a cholesteric liquid crystal layer having a central wavelength of selective reflection at 350 nm or more and less than 490 nm,
The windshield glass according to claim 11, wherein central wavelengths of selective reflection of each of the four or more cholesteric liquid crystal layers are different from each other.
13. The windshield according to claim 12, wherein, among the four or more cholesteric liquid crystal layers, the cholesteric liquid crystal layer closest to the λ / 2 retardation layer is a cholesteric liquid crystal layer having a central wavelength of selective reflection at 350 nm or more and less than 490 nm. Glass.
The windshield glass according to any one of claims 1 to 13, wherein at least one selected from the group consisting of the first resin film and the second resin film contains polyvinyl butyral.
A head-up display system comprising the windshield glass according to any one of claims 1 to 14 and a projector.
A head-up display system comprising the windshield glass according to any one of claims 1 to 8 and a projector,
The head-up display system in which the base material, the half mirror film, and the projector are arranged in this order.
A head-up display system comprising the windshield glass according to any one of claims 6 to 9 and a projector,
A head-up display system in which the circularly polarized light reflection layer, the retardation layer, and the projector are arranged in this order.
A laminated film comprising a substrate and a half mirror film,
The half mirror film is bonded to the substrate by an adhesive layer on a part of the main surface of the substrate,
The half mirror film includes a circularly polarized light reflection layer,
The circularly polarized light reflection layer includes three or more cholesteric liquid crystal layers having a central wavelength of selective reflection in the visible light region,
The substrate is a polyethylene terephthalate film,
A laminated film in which the elastic modulus of the base material is 3 GPa to 10 GPa and the thickness of the base material is 150 μm to 500 μm.