WO2009123339A1 - Windshield for vehicle - Google Patents

Abstract

A windshield for a vehicle containing a base material, and a polarizing film, where the windshield forms an angle δ with a horizontal reference plane, and the angle δ is 20 degrees to 50 degrees, and where a line on which the horizontal reference plane intersects with the base material and the high absorption axis of the polarizing film forms an angle φ defined as follows: (-0.0130 x δ2 + 1.03 δ - 12.5) degrees ≤ φ ≤ (0.00792 x δ2 + 0.0879 δ + 24.4) degree

Description

DESCRIPTION WINDSHIELD FOR VEHICLE

Technical Field The present invention relates to a windshield for a vehicle, specifically a windshield suitable for an automobile.

Background Art

There has been a safety issue at the time of driving a car (or any other vehicle) during a day when a strong ray of sunlight falls, that the visibility of driver is reduced as a result of the reflections of the interior structures such as a dashboard or the like on a windshield of the car. Moreover, contrary to the currently increasing needs for free design such as use of colors or pattern in a compartment of a car, there still has been an inconvenience such that only dark colors can be used for the design of the area around the dashboard or the like due to the problems of the reflections.

To overcome this problem, Patent Literature 1, for example, proposes a laminated glass in which two glass panels, each coated with an anti-reflection layer, are laminated such that the anti-reflection layers face outside. Further, Patent Literature 2 discloses a reflection-reduced glass for a vehicle, in which on at least one surface of a transparent glass substrate, a thin film layer having a refractive index nl of 1.8 to 1.9 and a thickness of 700 A (70 nm) to 900 A (90 nm) is laminated as a first layer from the glass surface, a thin film layer having a refractive index n2 of 1.4 to 1.5 and a thickness of 1,100 A (110 nm) to 1,300 A (130 nm) is laminated as a second layer on the thin film of the first layer, and in which the reflection on the surface of the thin film layer is reduced at 4.5% to 6.5% with respect to the incident visible light which is incident on the thin film layer at an incident angle of 50 degrees to 70 degrees to the vertical line of the surface. In the case where the reflection-reducing treatment is performed on the outer surface of the windshield for a vehicle as in Patent Literature 1 and Patent Literature 2, however, the outer surface of the windshield is rubbed by windshield wipers which are used so as to maintain a visibility at the time of driving for safety, then the reflection-reduced film is worn out, and therefore it causes a problem such that the characteristic of the optical thin film utilizing the interference of light cannot be maintained. The outer surface-treated windshield of a vehicle has another problem in terms of durability such that the depositions of dirt or the like significantly increases the reflectance due to the change in the conditions of light interference, and the depositions of the dirt becomes visible. If only one side is treated for anti-reflection, the backside reflection from the outer surface which is not anti-reflection treated is remained, and the total effect of anti-reflection is limited to the reduction of approximately 30%, which is not sufficiently satisfactory performance.

Furthermore, Patent Literature 3, also aiming at reducing the backside reflection from the windshield with an anti-reflection film as in Patent Literature 1 and Patent Literature 2, proposes to apply a polarizing film having a horizontal high absorption axis onto the plane between the laminated glasses of windshield or onto the inside surface of the windshield, in view of the fact that a principal polarized light component (S-polarized light) of the reflection light from the windshield for a vehicle, which enters a driver's horizontal front line of sight, has an electric field vibration component in horizontal level.

The approach in Patent Literature 3 may be effective for a horizontal front view, but once the driver shifts his eyes to the passenger seat side, the electric field vibration direction of S-polarized light is deviated from the high absorption axis of the polarizing film, so that the reflected image is more conspicuous compared to the case where a colored glass having a comparable transmittance is used.

Patent Literature 4 describes that by applying a layer which absorbs or scatter S-polarized light onto a dashboard, the reflection of the dashboard image on the windshield of a car can be prevented, which allows to improve the design of the dashboard.

However, the provision of the polarization to the dashboard by the absorption inevitably darkens the dashboard, and so cannot sufficiently improve the design thereof. Moreover, in the ordinary use of a car, the user often puts documents or small articles on the dashboard. In such a case, it is apparent that such an approach as in Patent Literature 4 cannot prevent the reflection of such documents or small articles on the windshield. Further improvement continues to be demanded.

Patent Literature 1^". Japanese Utility Model Application LaidOpen (JP-U) No. 05-69701

Patent Literature 2- Japanese Patent Application LaidOpen (JP-A) No. 04-357134

Patent Literature 3: Japanese Patent Application Laid-Open (JP-A) No. 2007-334150 Patent Literature 4- Japanese Patent Application Laid-Open (JP-A) No. 2006-56413

Disclosure of the Invention

The object of the present invention is to provide a windshield for a vehicle, which is suitably used for a windshield for a vehicle such as an automobile in which a driver's seat is placed near the left side or right side if looked at from the front, and which lowers a reflected image of the inner structure of the vehicle reflected from the outer surface of the windshield not only in the plane front view but also in a wider range of the windshield, so as to enhance the safety and the design of the inner structure.

The present inventors have extensively studied how to solve the above problems, and reached the following findings. With regard to the unwanted appearance of the reflected image which is a problem in an automobile or the like, it has been found that the light reflected from the surface of the windshield and entering the driver's eyes has polarization, and the electric vibration direction of its major polarizing component (S-polarized light) is only horizontal direction component as long as only the horizontal front view of the driver is considered, but if the whole surface of the windshield is considered, the electric vibration direction of its major polarizing component is on a tangential direction of a concentric circle whose center is the point where the driver's visual line vertically intersects with a plane including the surface of the windshield.

Moreover, it has been found that in a vehicle typified by an automobile, the driver's seat is set either near left side or right side from the center line of the windshield, and in such a vehicle, a polarizing film having a high absorption axis in a horizontal plane has not sufficient anti-reflection effect in a visual line from the side of the passenger seat.

The present invention has been accomplished based on the above-mentioned findings of the present inventors, and includes the following aspects to solve the problems. <1> A windshield for a vehicle, containing; a base material, and a polarizing film, where the angle 8 formed with a horizontal reference plane is 20 degrees to 50 degrees, where a line on which the horizontal reference plane intersects the base material and the high absorption axis of the polarizing film forms the angle φ defined as follows;

(-0.0130 x δ² + 1.03 δ - 12.5) degrees < φ < (0.00792 x δ² + 0.0879 δ + 24.4) degrees.

<2> The windshield for a vehicle according to <1>, where the angle φ is (0.00792 x δ² + 0.0879 δ + 14.4) degrees + 5 degrees.

<3> The windshield for a vehicle according to <1>, where the angle φ is

(-0.0130 x δ² + 1.03 δ - 2.46) degrees ± 5 degrees.

<4> The windshield for a vehicle according to any one of <1> to <3>, where the polarizing film is disposed on the face of the base material, facing the horizontal reference plane.

<5> The windshield for a vehicle according to any one of <1> to <3>, where the base material is a laminated glass having two glass panels and an intermediate layer interposed therebetween, and the intermediate layer contains the polarizing film. <6> The windshield for a vehicle according to any one of <1> to <4>, where the 7030 base material is a polymer, and has the polarizing film either on the surface of or inside of the base material.

<7> The windshield for a vehicle according to any one of <1> to <6>, where the windshield has an anti-reflection film either on both surfaces or the outermost surface facing the horizontal reference plane.

<8> The windshield for a vehicle according to any one of <1> to <7>, where the vehicle is an automobile.

According to the present invention, the conventional problems can be solved, and there is provided a windshield for a vehicle, which is suitably used for a windshield for a vehicle such as an automobile in which a driver's seat is placed near the left side or right side if looked at from the front, and which lowers a reflected image of the inner structure of the vehicle reflected from the outer surface of the windshield not only in the plane front view but also in a wider range of the windshield, so as to enhance the safety and the design of the inner structure.

Brief Description of the Drawings

FIG. 1 is a schematic diagram illustrating a view, from inside of the vehicle, of polarizing axis of S-polarized light which is reflected from the windshield and enters the driver's eyes in a right-hand-drive vehicle.

FIG. 2 is a schematic diagram illustrating the case where the high absorption axis of the polarizing film is set horizontally to the horizontal reference plane in a right-hand-drive vehicle.

FIG. 3A is a schematic diagram illustrating the case where the high absorption axis of the polarizing axis has a certain inclination to a line at which T/JP2000/057030 the horizontal reference plane intersects the base material plane in a right-hand- drive vehicle.

FIG. 3B is a schematic diagram illustrating the case where the high absorption axis of the polarizing axis has a certain inclination to a line at which the horizontal reference plane intersects the base material plane when applied to a left-hand- drive vehicle.

FIG. 4 is a diagram illustrating the measuring points (6 points) on the windshield in the Examples in a right-hand- drive vehicle.

FIG. 5 is a graph showing the results of reflectance simulation in the Examples, and indicating that the angle φ of the absorption axis of the polarizing film at which total reflectance of whole region of the windshield at an inclination angle δ is minimum is within the following range: (0.00792 x δ² + 0.0879 δ + 14.4) degrees ± 5 degrees.

FIG. 6 is a graph showing the results of reflectance simulation in the Examples, and indicating that in the range where total of reflectance in a driver's seat side at an inclination angle δ is not stronger than a colored glass, the magnitude of the angle φ of the absorption axis of the polarizing film which can suppress the reflection from whole windshield to the lowest level is in the following range- (-0.0130 x δ² + 1.03 δ - 2.46) degrees + 5 degrees. FIG. 7 is a graph showing the results of comparison between measured values obtained by actually measuring surface reflectance of the glass substrate on which the antirefLective coating is applied and the calculated values.

Best Mode for Carrying Out the Invention The windshield of the present invention contains at least a base material 057030 and a polarizing film, and if necessary, an antireflective film or other layers.

The above-mentioned windshield for a vehicle has a great effect of preventing an unwanted reflection if configured to the above. This is because that only the antireflective film applied onto the surface of the windshield facing inside the vehicle cannot prevent the reflection on the outer surface of the windshield of the vehicle, and that only the polarizing film cannot prevent the reflection on the inner surface of the windshield of the vehicle.

In the case where the antireflective film is used, since the intensity of light entering into the windshield is stronger in such a manner as to offset against the reduced amount of reflection on the inside surface of the vehicle, the intensity of reflected light from the outer surface of the windshield is correspondingly stronger; and since the main component of the reflected light is a reflected light from the outer surface of the windshield, the effect achieved by a polarizing film is large. For example, given that the surface reflectance of light that entered into the base material at a certain angle is 10% and the intensity of the incident light 10 is 1, the relationship between intensity of reflected light from the inner surface of the windshield II, intensity of reflected light from the outer surface of the windshield 12, and whole intensity of the reflected light (Il + 12) is as follows;

11 = 1 x 0.1 = 0.1 12 = 1 x 0.9 x 0.1 x 0.9 » 0.08

(Il + 12) = 0.1 + 0.08 = 0.18

If this relationship is applied to an antireflective film, and given that the reflectance on the inner surface of the windshield is 0, the relationship between the intensity of the reflected light from the inner surface of the windshield 13, the intensity of the reflected light from the outer surface of the windshield 14, and the intensity of whole reflected light (13 + 14) is as follows; 13 = i x o = 0 14 = 1 x 1 x 0.1 x 1 = 0.1 (13 + 14) = 0 + 0.1 = 0.1 If the intensity of light from the outer surface of the windshield 12 or 14 is lowered by 50%, the intensity of the whole reflected light when the antireflective film is not used (Il + 12)', and the intensity of the whole reflected light when the antireflective film is used (13 + 14)' are as follows:

(Il + 12)' = 0.1 + 0.08 x 0.5 = 0.14 (13 + 14)' = 0 + 0.1 x 0.5 = 0.05

Therefore, when a 50% polarizing film is used, the whole reflected light reducing ratio Rl without using an antireflective film, and the whole reflected light reducing ratio R2 using an antireflective film are as follows;

Rl = (Il + 12)' / (Il + 12) = 0.78 R2 = (13 + 14)' / (13 + 14) = 0.5

Thus, the effect of lowering the reflection due to the polarizing film is more remarkable when the anti-reflection film is disposed in the inner surface of the windshield. Conversely, it is suggested that in the region where a reflection reducing effect with the polarizing film is not obtained, the reflection reducing effect is poorer in the case where the anti-reflection film is used.

As seen in FIG. 1 (in this case, a driver's seat is placed at right-hand side to the direction of travel; namely, right-hand- drive vehicle," FIG. 2, FIG. 3A and FIG. 4 are also right-hand- drive cases), the vibrational direction of an S-polarized light in the windshield is represented by the tangential direction of a concentric circle whose center is a point at which the driver's visual line vertically intersects 7030 with the plane including the surface of the windshield. This is because the direction of the light entering the eyes is parallel to the line getting through the center of the concentric circle, and so the tangential line of the concentric circle is perpendicular to the incident light, and the polarizing axis "a" of S-polarized light is perpendicular to the incident light and parallel to the incident interface. Given that the high absorption axis of the polarizing film is set parallel to a horizontal reference plane, as illustrated in FIG. 2, in the passenger- side region, the angle is large which is formed by the polarizing axis "a" of S-polarized light of the incident light entering the driver's eyes and the high absorption axis "b" of the polarizing film. Thus, if the driver shifts his eyes to the passenger-side, not only the effect of the polarizing film for reducing unwanted reflection cannot be expected, but also the reflection is rather stronger than the case where a color glass that recently prevails is used. If the high absorption axis of the polarizing film is set to have a certain inclination against the line where the horizontal reference plane meets the base material plane, as illustrated in FIG. 3A, in the passenger- side region, the angle is small which is formed by the polarizing axis "a" of S-polarized light of the incident light entering the driver's eyes and the high absorption axis "b" of the polarizing film. In addition, since the line (region) "c" passing the points at which the polarizing axis "a" of S-polarized light and the high absorption axis "b" of the polarizing film are parallel to each other becomes longer (larger), the inclination of the high absorption axis "b" of the polarizing film at a certain angle can enhance the unwanted reflection-preventive effect of the polarizing film.

Accordingly, in the present invention, in order to reduce, in the whole windshield area, the region where the polarizing film is not sufficiently effective 30 in preventing the unwanted reflection, as seen in FIG. 3A and FIG. 3B, the high absorption axis is set to have a certain inclination against the line intersecting the horizontal reference plane and the surface of windshield, and preferably a anti-reflection film is disposed, so that the region where the anti-reflection effect by the polarizing film is markedly displayed can be larger compared to the case where the high absorption axis of the polarizing film is set to run parallel to the horizontal reference plane. -Disposition angle of polarizing film-

The disposition angle of the polarizing film, the angle φ (see FIG. 3A and FIG. 3B) formed by the line where the horizontal reference plane meets the base material plane and the high absorption axis of the polarizing film is (-0.0130 x δ² + 1.03 δ - 12.5) degrees < φ < (0.00792 x δH 0.0879 δ + 24.4) degrees, preferably (0.00792 x δ² + 0.0879 δ + 14.4) degrees + 5 degrees, more preferably (-0.0130 x δ² + 1.03 δ - 2.46) degrees ± 5 degrees. In the equations, the symbol "δ" is an angle formed by the windshield and the horizontal reference plane (i.e., the angle of inclination of the windshield), and is 20 degrees to 50 degrees, preferably 25 degrees to 40 degrees.

If the angle φ is 5 degrees or less, there is no clear difference in the effect from the case where the high absorption axis of the polarizing film is set parallel to the horizontal reference plane, and so the effect of reducing the unwanted reflection in the passenger seat side cannot be obtained. If the angle φ is 45 degrees or more, the angle formed by the intersection of the polarizing axis of S-polarized light and the high absorption axis of the polarizing film is so great in front of the driver that the unwanted reflection in front of the driver is more remarkable than that on a color glass. Here, the term "horizontal reference plane" means a plane regarded as horizontal standard plane in a vehicle, for example, which corresponds to a dashboard plane in an automobile.

The "high absorption axis of the polarizing film" means the axis of the maximum absorption when a linear polarized light hits the polarizing film, and can be determined by locating the axis that indicates maximum absorption with a polarized light absorption measurement of the polarizing film.

In a vehicle employing a polarizing film, the angle φ formed by the intersection of the horizontal reference plane and the base material plane (standard line), and the high absorption axis of the polarizing film can be obtained by observing the windshield of a vehicle with a polarizing plate whose high absorption axis is predetermined, and by rotating the polarizing plate and observing the change in light and darkness produced according to the angle formed by the polarizing plate and the high absorption axis of the polarizing film of the windshield. More specifically, when the light through the rotated polarizing plate is darkest, the direction perpendicular to the high absorption axis of the polarizing plate is the high absorption axis of the polarizing film of the windshield, and the angle φ is determined by measuring the angle formed by the high absorption axis and the standard line. -Optical performance of polarizing film-

The provision 29 (3) of the safety standard of the Road Trucking Vehicle Law provides for the average transmission of a windshield at a wavelength ranging from 380 nm to 780 nm, stipulating that the transmission must be 0.70 or more. Taking this into consideration, when the polarizing film is applied to the windshield, the ordinary light transmission through the windshield is preferably 0.75 to 0.85, more preferably 0.70. The orientation degree of the polarizing film is preferably 0.65 or more, more preferably 0.8 or more, even more preferably 0.9 or more.

A material for the polarizing film is not particularly limited so long as it has the above-mentioned optical properties, and may be selected properly according to the purpose. Examples thereof include anisotropic metallic nanoparticles, carbon nanotubes, metallic complexes, dichromatic pigments, and iodine/PVA-based materials. Of these, anisotropic metallic nanoparticles and carbon nanotubes are more preferable in terms of durability. A method for producing the polarizing layer is not particularly limited, and may be selected properly according to the purpose, or according to the material of the polarizing layer.

A thickness of the polarizing film is not particularly limited, and selected properly according to the purpose, and is preferably 50 nm to 300 μm. <Base material>

As the base material, a glass (i.e., glass base) is most suitable, because glass has a good track record in terms that glass has a 12-year durability which is an approximate life span of a vehicle in an environment open to wind and rain, and does not disturb the polarized light. Recently, however, in a plate molding of a polymer such as a norbornene-based polymer, a plastic is provided having a high durability and high isotropy, and scarcely disturbing the polarization, and accordingly it is possible to use a material other than glass as a base material. -Glass base material- Glass as a base material is not particularly limited and may be selected properly according to the purpose. Examples thereof include a monolayer glass, a laminated glass, a strengthened laminated glass, a double glazing, a strengthened double glazing, and a laminated double glazing.

Examples of a plate glass constituting the glass base material include a transparent plate glass, a figured glass, a wire plate glass, a line wire glass, a reinforced plate glass, a heat-reflecting plate glass, a heat-absorbing plate glass, a Low-E plate glass, and other various plate glasses.

The glass base material may be colorless or colored glass, so long as the glass is transparent.

The thickness of the glass base material is not particularly limited, and may be selected properly according to the purpose. The thickness is preferably 2 mm to 20 mm, more preferably 4 mm to 10 mm.

The plate glass may be used solely or in combination of two or more of the same kind or different kinds. -Laminated glass- The laminated glass is formed by combining two plate glasses with an intermediate layer disposed between the two plate glasses. Since the laminated glass is not scattered as pieces of broken glass even when the glass is broken by the external impact, it is safe and accordingly used widely for a windshield of a vehicle such as an automobile and a window glass of a building or the like. In the case where the laminated glass is used for an automobile, a fairly thin glass is used recently to make the weight light. Two plates of the glasses, each having a thickness of 1 mm to 3 mm, are combined with an adhesive layer having a thickness of 0.3 mm to 1 mm to form a laminated glass having a total thickness of about 3 mm to 6 mm. As the above two plate glasses, various plate glasses as recited above may be used properly according to the purpose.

The thermoplastic resin to be used for the intermediate layer is exemplified by a polyvinyl acetal resin, a polyvinyl alcohol resin, a polyvinyl chloride resin, a saturated polyester resin, a polyurethane resin, and an ethylene -vinyl acetate copolymer. Of these, a polyvinyl acetal resin is more preferable because it can provide an intermediate layer excellent in a balance of performances such as transparency, weather resistance, strength, and adhesive power, and the like.

The polyvinyl acetal resin is not particularly limited, and may be selected properly according to the purpose. Examples thereof include a polyvinyl formal resin obtained by reacting a polyvinyl alcohol (hereinafter, may be abbreviated to a "PYA.") with formaldehyde! a polyvinyl acetal resin in a narrow sense obtained by reacting a PVA with acetoaldehyde; and a polyvinyl butyral resin obtained by reacting a PVA with n-butylaldehyde. The PVA to be used for the synthesis of the polyvinyl acetal resin is not particularly limited, and may be selected properly according to the purpose. The PVA is a PVA having an average polymerization degree of, preferably 200 to 5,000, more preferably 500 to 3,000. The polyvinyl acetal resin using a PVA having an average polymerization degree of less than 200 may provide an intermediate layer having too weak strength. The polyvinyl acetal resin using a PVA having an average polymerization degree of more than 5,000 may cause any inconvenience when molding the polyvinyl acetal resin.

The polyvinyl acetal resin is not particularly limited, and may be selected properly according to the purpose. The polyvinyl acetal resin preferably has an acetalation degree of 40% by mole to 85% by mole, more preferably 50% by mole to 75% by mole. A polyvinyl acetal resin having an acetalation degree of less than 40% by mole or more than 85% by mole may sometimes have difficulty in the synthesis in terms of reaction mechanism. The acetalation degree can be measured in accordance with JIS K6728. The intermediate layer may contain, in addition to the thermoplastic resin, a plasticizer, a pigment, an inorganic oxide, an inorganic nitride, an adhesive adjuster, a coupling agent, a surfactant, an antioxidant, a heat stabilizer, a light stabilizer, a fire retardant, an antistatic agent, an ultraviolet absorber, a heat ray shielding agent, a moisture resistance enhancer, and a conducting material. The intermediate layer may be a laminated layer that includes, as a part thereof, a functional layer containing any of the above-recited additives. The uppermost surface of the intermediate layer may be embossed in accordance with the method as described in JP-A No. 2007-22089 because such embossing does not impair the performance of a functional layer, including the polarizing layer. Moreover, the intermediate layer may have a sound insulation performance as referred to, for example, in JP-A No. 2008-37018.

The polarizing plate in the present invention relates to prevention of unwanted reflection, namely to reduce the reflectance of visible light. Accordingly, to achieve the maximum effect of the present invention, a weighting factor average of visible light transmission of the above mentioned additives are preferably 100% or so. Most of the above mentioned additives actually used in an intermediate film for a laminated glass are designed to have as little absorption as possible in the wavelength range of visible light such that the additives perform their function without affecting the color of the glass. Likewise, in the present invention, it is possible to use the additives selected from 7030 those commonly used for an intermediate film for the glass, and will basically be possible to use, in combination, functional additives which might be developed in the future, unless they have strong absorption or reflection performance within a wavelength range of visible light. Such functional additives will not have a bad influence on the effect of preventing the unwanted reflection of the present invention. Specific examples of the additives include the plasticizer, the adhesive power regulator, and the ultraviolet absorber as described in paragraphs [0042] to [0056] of JP-ANo. 2006-514110; the infrared shielding agent as described in paragraphs [0020] to [0023] of JP-ANo. 2008-024538 (Japanese Patent Application No. 2006-197119) and paragraphs [0023] to [0024] of Japanese Patent Application No. 2006-531979; and the moisture resistance enhancer as described in paragraphs [0012] to [0018] of Japanese Patent Application No. 2006-528948. The method of forming the intermediate layer is not particularly limited, and can be selected properly according to the purpose. The method is exemplified by the process in which a composition containing a thermoplastic resin and other components are kneaded, and then the mixture was formed as a sheet by a conventional method such as an extrusion method, a calendar method, press method, casting method, and inflation method.

The thickness of the intermediate layer is not particularly limited, and can be selected properly according to the purpose. Preferable thickness is 0.3 mm to 1.6 mm.

The intermediate layer is preferably an intermediate film for a laminated glass in which plural films containing the above-mentioned thermoplastic resin and/or the functional resin which have good adhesiveness with glass are laminated, and preferably includes a polarizing film as a part of all of the laminates, in terms of productivity, durability, and the like. The polarizing fibn may be disposed on one surface of the laminated glass.

A method of producing the laminated glass is not particularly limited, and can be selected properly according to the purpose. For example, the laminated glass is produced by the following method. The polarizing film to be used for the windshield for a vehicle is placed between two transparent glass plates with the intermediate layer, and the resultant laminated glass body is placed in a vacuum bag such as a rubber bag, and this vacuum bag is connected to an exhaust apparatus to deaerate under reduced pressure such as the pressure within the vacuum bag is about -65 kPa to -100 kPa, carrying out a preliminary adhesion at a temperature of about 70°C to 110°C. The preliminary adhered laminated glass body is put into an autoclave and subjected to the final adhesion by heating and applying pressure under the condition where the temperature is 120°C to 150°C and the pressure is 0.98 MPa to 1.47 MPa, whereby the target laminated glass is yielded.

As for the laminated glass used for the windshield for an automobile, it is preferable to use a plate glass having a visible light weighted average transmission (JIS R3106) of ordinary ray of 85% or more and less than 100%, more preferably 90% or more and less than 100%. Moreover, the visible light weighted average transmission of ordinary ray in the form of the laminated glass is preferably adjusted mainly by the polarizing layer of the intermediate layer to 70% to 85%, more preferably close to 70% in terms of prevention of unwanted reflection. Here, the visible light weighted average transmission of ordinary ray of the laminated glass containing the polarizing layer of the present invention can be determined by measuring, at the same measuring point, the linear polarized light transmission by changing the angle of the high absorption axis of the incident linear polarized bight, and calculating the average of the maximum value and the minimum value of the weighted average transmission of the linear polarized light. The visible light weighted average transmission of ordinary ray is fixed by law as 70% or more in safety terms, and if it exceeds 85%, the effect of preventing unwanted reflection can be insufficient. The laminated glass preferably has a thickness of 3 mm to 6 mm, and also at least an ultraviolet ray absorption performance and a heat ray shielding performance in addition to the polarizing performance. The ultraviolet ray absorption performance and the heat ray shielding performance may be imparted to the intermediate layer or glass. It is more preferable that at least one surface of the laminated glass is covered with antireflective coating. <AntirefLective film>

The antireflective film is preferably disposed on both surfaces of the base material or on the outermost surface facing to the horizontal reference plane. The antireflective film is not particularly limited and can be selected properly according to the purpose, provided that it has practically sufficient durability and heat resistance. Preferable examples thereof include (l) a film on which fine irregularities are formed, (2) a structure of two layered film combining a high refractive index film and a low refractive index film, (3) a structure of three layered film formed by laminating successively a medium refractive index film, high refractive index film and low refractive index film. Of these, (2) and (3) is more preferable.

These antireflective films may be formed directly by a sol- gel method, a spattering method, a vapor deposition method, or a CVD method. Alternatively, T/JP2000/057030 the antireflective film may be formed both on the transparent base by a coating method, including a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating method, a micro gravure method and a extrusion coating method, and on the surface of the base material glass by sticking or adhering the antireflective film.

As mentioned above, the antireflective film preferably has a layered structure having at least one layer (a high refractive index layer) of a refractive index higher than a low refractive index layer on the transparent base, and successively the low refractive index layer (the outermost layer).

To configure the at least one layer of a refractive index higher than the low refractive index layer as a two layer structure, it is preferable to form successively on the transparent base a medium refractive index layer, a high refractive index layer, and a low refractive index layer (the outermost layer). An antireflective film having such a structure is designed to have a refractive index satisfying the relationship "the refractive index of the high refractive index layer > the refractive index of the medium refractive index layer > the refractive index of the transparent base > the refractive index of the low refractive index layer". The refractive index of each refractive index layer is relative to each other. -Transp arent base-

The transparent base is preferably a plastic film. Examples of materials of the plastic film include cellulose acylate, polyamide, polycarbonate, polyester (e.g., polyethylene terephthalate and polyethylene naphthalate), polystyrene, polyolefin, polysulfone, polyethersulfone, polyarylate, polyetherimide, polymethylmethacrylate, and polyetherketone. -High refractive index layer and medium refractive index layer—

The high refractive index layer of the antireflective film is preferably constituted of a hardening film having a high refractive index and containing inorganic compound ultra fine particles having an average particle diameter of 100 nm or less.

The high refractive index inorganic compound fine particle is exemplified by an inorganic compound having a refractive index of 1.65 or more, preferably 1.9 or more. Examples thereof include an oxide of Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and a complex oxide containing any of these metallic atoms. More specific examples include an inorganic fine particle containing as a main component, titanium dioxide containing at least one element selected from Co, Zr and Al (hereinafter, may be called the "specific oxide"). Of the elements, Co is more preferable.

Total amount of Co, Al and Zr with respect to Ti is preferably 0.05% by mass to 30% by mass, more preferably 0.1% by mass to 10% by mass, more preferably 0.2% by mass to 7% by mass, more preferably 0.3% by mass to 5% by mass, even more preferably 0.5% by mass to 3% by mass.

Co, Al, and Zr are present inside or on the surface of an inorganic fine particle containing titanium dioxide as a main component. It is preferable that Co, Al, and Zr are present inside an inorganic fine particle. It is more preferable that Co, Al, and Zr are present both inside and on the surface of an inorganic fine particle. These metallic elements may be present as oxides.

Other preferable inorganic particle is a particle of a complex oxide of titanium element and at least one metallic element (hereinafter, may be abbreviated by "Met") selected from metallic elements whose oxides have a refractory index of 1.95 or more," and the complex oxide is an inorganic fine particle (hereinafter, may be called the "specific complex oxide") doped with at least one metallic ion selected from Co ion, Zr ion, and Al ion.

Examples of the metallic element whose oxide has a refractory index of 1.95 or more include Ta, Zr, In, Nd, Sb, Sn, and Bi. Of these, Ta, Zr, Sn, and Bi are more preferable.

The amount of the metallic ion for doping the complex oxide is preferably 25% by mass or less with respect to the whole amounts of metals [Ti+Met] in terms of the maintenance of the refractory index, more preferably, 0. 05% by mass to 10% by mass, more preferably 0.1% by mass to 5% by mass, even more preferably 0.3% by mass to 3% by mass.

A metallic element in the doped complex oxide may be present as either a metallic ion or a metallic atom, and is preferably present properly from the surface to the inside of the complex oxide. It is more preferable for the metallic element to be present both on the surface and the inside of the complex oxide.

Examples of the method of producing the ultra fine particles include a method in which the surface of the particles is treated with a surface treatment agent, a method in which a core-shell structure is formed containing high refractive index particles as the core, and a method in which specific dispersant is used in combination.

The surface treating agent for use in a method in which the surface of the particles is treated with a surface treatment agent is exemplified by a silane coupling agent as disclosed in JP-ANos. 11-295503, 11-153703, and 2000-9908; an anionic compound or an organic metal coupling agent as disclosed in JP-A No. 2001-310432. 30

As the method in which a core-shell structure is formed containing high refractive index particles as the core, the technique disclosed in JP-A No. 2001-166104 or U.S. Patent Application Publication 2003/0202137.

The method in which specific dispersant is used in combination is exemplified by the technique as disclosed in JP-A No. 11-153703, U. S. Patent No. 6210858, or JP-ANo. 2002-277606.

The material for forming the matrix is not particularly limited, and can be selected. Examples thereof include a thermoplastic resin and a hardening resin. More specifically, preferable is at least one of the compositions selected from a composition containing a poly-functional compound containing at least two polymerizable groups which is capable of radical polymerization and/or cationic polymerization; and a composition containing a hydrolyzable group -containing organic metallic compound and its partial condensate. Examples thereof include a compound described in any one of JP-ANos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401.

Also preferable is a hardening film obtained from a composition containing a colloidal metallic oxide obtained from a hydrolyzed condensate of metallic alkoxide and a metallic alkoxide, which is exemplified by that described in JP-A No. 2001-293818. The refractive index of the high refractive index layer is preferably 1.70 to

2.20, and the thickness of the high refractive index layer is preferably 5 nm to 10 μm, more preferably 10 nm to 1 μm.

The refractive index of the mediate refractive index layer is adjusted to have a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the medium refractive index layer is preferably 1.50 to 1.70, and the thickness of the medium refractive index layer is preferably 5 nm to 10 μm, more preferably 10 nm to 1 μm.

-Low refractive index layer- The low refractive index layer is preferably laminated successively on the high refractive index layer. The refractive index of the low refractive index layer is preferably 1.20 to 1.55, more preferably 1.30 to 1.50.

The low refractive index layer is preferably formed as the outermost layer having abrasion resistance and antifouling property. An effective way to enhance the abrasion resistance is to impart the surface slipping property by using the conventional means as used for a thin film layer, such as introduction of silicone or fluorine,

The refractive index of the fluorine "containing compound is preferably 1.35 to 1.50, more preferably 1.36 to 1.47. The fluorine-containing compound is preferably a compound containing a fluorine atom in an amount 35% by mass to 80% by mass, and containing functional groups capable of cross-linking or polymerization.

Examples of the compounds include those described in [0018] to [0026] of JP-ANo. 09-222503; [0019] to [0030] of JP-ANo. 11-38202; [0027] to [0028] of JP-A No. 2001-40284; JP-A- No. 2000-284102; or JP-A No. 2004-45462.

The silicone compound is preferably a compound having a polysiloxane structure, having hardening functional groups or polymerizable functional groups in a polymer chain, and having a bridged structure in the film. Examples thereof include a reactive silicone [(e.g., SILAPLANE produced by Chisso Corporation), and a polysiloxane having silanol groups at both terminals (JP-A No. 11-258403 or P2009/057030 the like)].

The cross-linking or polymerization reaction of a fluorine- and/or siloxane- containing polymer having groups capable of cross-linking or polymerization is preferably performed concurrently with or after the coating of a coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer, and the like, by exposure to light or heating. The polymerization initiator and the sensitizer may be selected from conventionally used ones.

It is also preferable to use a sol- gel hardening film obtained by hardening with a condensation reaction, in the presence of a catalyst, an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group -containing silane coupling agent.

Examples thereof include polyfluoroalkyl group containing silane compound or its partial hydrolyzed condensate (a compound recited in any of JP-A Nos. 58-142958, 58-147483, 58-147484, 09-157582, and 11-106704); a silyl compound containing poly[perfLuoroalkylether] group which is a long chain group containing fluorine (a compound recited in any of JP-ANos. 2000-117902, 2001-48590, and 2002-53804).

The low refractive index layer preferably contains, in addition to the above additives, a low refractive index inorganic compound having a primary particle diameter of 1 nm tolδO nm such as a filler (e.g., silica, a fluorine-containing particle (magnesium fluoride, calcium fluoride and barium fluoride)).

The low refractive index layer is preferably made of hollow inorganic fine particles in order to effectively prevent the increase of refractive index. The hollow inorganic fine particle preferably has a refractive index of 1.17 to 1.40, more preferably 1.17 to 1.37, even more preferably 1.17 to 1.35. The term "refractive index" herein used means a refractive index of the whole particles, not a refractive index of only the shell that constitutes the hollow inorganic particle. The average particle size of the hollow inorganic fine particles in the low refractive index layer is preferably 30% to 100% of the thickness of the low refractive index layer, more preferably 35% to 80% of the thickness of the low refractive index layer, even more preferably 40% to 60% of the thickness of the low refractive index layer.

In other words, if the thickness of the low refractive index layer is 100 nm, the particle diameter of the inorganic fine particle is preferably 30 nm to 100 nm, more preferably 35 nm to 80 nm, even more preferably 40 nm to 60 nm.

Here, the refractive indices of these hollow inorganic fine particles can be measured by use of Abbe refractometer (produced by Atago Co., Ltd.).

Other additives may be added such as the organic fine particles as described in paragraphs [0020] to [0038] of JP-ANo. 11-3820, a silane coupling agent, a lubricant, a surfactant, or the like.

If the low refractive index layer is placed under the outermost layer, the low refractive index layer may be formed by a gas phase method (e.g., a vacuum deposition method, a spattering method, an ion plating method, a plasma CVD method, or the like), but is preferably formed by a coating method in terms of cost saving.

The thickness of the low refractive index layer is preferably 30 nm to 200 nm, more preferably 50 nm to 150 nm, even more preferably 60 nm to 120 nm.

The windshield for a vehicle may include other layers, if necessary, such as a hard coat layer, a front scattering layer, a primer layer, an antistatic layer, an under coat layer, a protective layer, or the like. <Use of windshield for vehicle>

As mentioned earlier, the windshield for a vehicle of the present invention has a polarizing film in which the high absorption axis inclines at a certain degree φ with respect to the line intersecting the base material plane and the horizontal reference plane, resulting in an excellent antireflective effect of the ray, and accordingly is widely used for a windshield for various vehicles. The windshield for a vehicle of the present invention is more suitably used as a windshield for an automobile in which a driver's seat is deviated from the center of the windshield to either left side or right side position (a right handle system (FIG. 3A), that is, the driver's seat is positioned at the right side to the direction of travel, has a configuration opposite to a left handle system (FIG. 3B)), and the inclination angle of the windshield is small, because the reflection from the outer surface of the windshield of the automobile can be reduced and unwanted reflection of the interior objects of the vehicle can be prevented. The windshield for a vehicle of the present invention, as mentioned above, can prevent unwanted reflection of the inside objects such as a dashboard and an outdoor light and the like, if used as a windshield of an automobile, and accordingly ensures the safety of the driver. It also enables to adopt an excellently designed dashboard with light-color or a pattern, which could not be used in the past. Moreover, since the high transmission direction of the polarizing film of the windshield of the automobile of the driver's own is not parallel to that of the windshield of an oncoming automobile, the inside of the oncoming automobile is hardly seen when compared to the case where the polarizing film is placed horizontally, resulting in the advantageous effect that mutual privacy is secured. EXAMPLES

Hereinafter, the Examples of the present invention will be explained, which do not impose any limitation on the present invention. In the following Examples and Comparative Examples, glasses having the dimension (50 mm long, 50 mm wide and 1 mm thick) were used, since the reflectance of the incident light from a windshield for an automobile as such was difficult to measure because of its large size. Example 1 -Polarizing plate having φ of 15 degrees-

Apolyvinylalcohol film was immersed in water at room temperature for 60 seconds, and then immersed in an aqueous solution of iodine (produced by Wako Pure Chemicals Industries Ltd.; 0.033% by mass) and potassium iodide (produced by Wako Pure Chemicals Industries Ltd.; 0.33% by mass) for 10 seconds at 40⁰C. Then the resultant film was immersed in an aqueous solution of boric acid

(produced by Wako Pure Chemicals Industries Ltd.; 4.0% by mass) and potassium iodide (produced by Wako Pure Chemicals Industries Ltd.; 4.0% by mass) at 60⁰C for 60 seconds, and the obtained film was extended by a factor of 5, and the extended film was dried, whereby a polarizing film was yielded. Next, on one surface of a white plate glass (0050- JFL; produced by

Matsunami Glass Ind., Ltd.), the polarizing film was pasted with an adhesive PD-Sl (produced by Panac Ind. Ltd.) such that the angle φ formed by the high absorption axis of the polarizing film and the line intersecting the horizontal reference plane and the base material plane was 15 degrees, whereby a glass covered with a polarizing film was yielded. 30

The reflectance of the obtained glass with the polarizing film at incident angles as shown in Table 1, and at an angle β formed by s-polarized axis of the incident light and high absorption axis of the polarizing film was measured in the following manner. Results are shown in Table 1. In addition, results of comparison of each windshield material without antireflection coating are shown in Table 2, and the results of comparing the angle φ are shown in Table 4. <Measurement of reflectance of glass samples>

Six representative points on the windshield for an automobile having an inclination angle δ of 35 degrees were selected (FIG. 4), the incident angles of the lights which were reflected on the each of the 6 points and entered into the driver's eyes and the angle β (0 degrees < β < 90 degrees) formed by the s-polarized axis and the high absorption axis of the polarizing film were obtained as shown in Table 1, and the absolute reflectance of Example 1 was measured with an ultraviolet visible spectrophotometer (V-560, produced by JASCO Corporation) and an absolute reflectance measuring unit (ARV-474S, produced by JASCO Corporation).

Each reflectance was measured by setting the antireflection layer side as an incident plane if the antireflection layer is present, and if the antireflection layer is not present, the glass side is set as an incident plane. The reflectance was measured using a light having a wavelength of 650 nm for the white plate glass or the white plate glass having antireflective coating, and a wavelength whose transmittance is 70% for other glasses. Example 2 -Polarizing plate, antireflective coating, φ 15 degrees- On a white plate glass (0050- JFL, produced by Matsunami Glass Ind., Ltd.), an antireflective layer

deposited through vacuum evaporation to obtain an antireflective glass. On the surface of the obtained antireflective glass, which surface is opposite to the side of the antireflective layer, the same polarizing film as in Example 1 was pasted such that the angle formed by the line intersecting the horizontal reference plane and the base material plane and the high absorption axis of the polarizing film was 15 degrees, to thereby obtain an antireflective glass having the polarizing film.

The reflectance of the resultant antireflective glass with the polarizing film was measured in the same manner as in Example 1, at an incident angle, and at an angle β formed by s-polarized axis of the incident light and the high absorption axis of the polarizing film, as shown in Table 1. Results are shown in Table 1, and results in which each windshield material having antireflective coating was compared is shown in Table 3. Example 3 —Polarizing plate, φ 25 degrees—

On a white plate glass (0050- JFL, produced by Matsunami Glass Ind., Ltd.), a polarizing film was pasted in the same way as in Example 1, such that the angle φ formed by the line intersecting the horizontal reference plane and the base material plane and the high absorption axis of the polarizing film was 25 degrees, to thereby the antireflective glass with a polarizing film was yielded. The reflectance of the resultant antireflective glass with the polarizing film was measured in the same manner as in Example 1, at an incident angle, and at an angle β formed by s-polarized axis of the incident light and the high absorption axis of the polarizing film, as shown in Table 1. Results are shown in Tables l and 4.

30 Example 4

-Polarizing plate φ 10 degrees-

On a white plate glass (0050-JFL, produced by Matsunami Glass Ind., Ltd.), a polarizing film was pasted in the same way as in Example 1, such that the angle φ formed by the line intersecting the horizontal reference plane and the base material plane and the high absorption axis of the polarizing film is 10 degrees, to thereby the antireflective glass with a polarizing film was yielded. The reflectance of the resultant antireflective glass with the polarizing film was measured in the same manner as in Example 1, at an incident angle, and at an angle β formed by s-polarized axis of the incident light and the high absorption axis of the polarizing film, as shown in Table 1. Results are shown in

Tables 1 and 4.

Example 5

-Polarizing plate φ 35 degrees- On a white plate glass (0050-JFL, produced by Matsunami Glass Ind.,

Ltd.), a polarizing film was pasted in the same way as in Example 1, such that the angle φ formed by the line intersecting the horizontal reference plane and the base material plane and the high absorption axis of the polarizing film is 35 degrees, to thereby the antireflective glass with a polarizing film was yielded. The reflectance of the resultant antireflective glass with the polarizing film was measured in the same manner as in Example 1, at an incident angle, and at an angle β formed by s-polarized axis of the incident light and the high absorption axis of the polarizing film, as shown in Table 1. Results are shown in Tables 1 and 4. Comparative Example 1 The reflectance of a white plate glass (0050-JFL, produced by Matsunami Glass Ind., Ltd.) was measured at the incident angle in Table 1. Results are shown in Table 2. Comparative Example 2 —White plate glass, antireflective coating-

On one surface of the white plate glass (0050-JFL, produced by Matsunami Glass Ind., Ltd.), an antireflective layer of MgF2 was deposited through vacuum evaporation to obtain an antireflective glass, and the reflectance of the antireflective glass was measured at an incident angle in Table 1. Results are shown in Table 3. Comparative Example 3 —Isotropic color filrn-

An acrylic resin (ARON S1006, produced by Toagosei Co., Ltd.) (25% by mass) and an organic pigment (G205, produced by Hayashibara Biochemical Lab., Inc.) (0.004% by mass) were dissolved in toluene, and the resultant solution was coated on a triacetylcellulose film, and the coated product was dried, whereby an isotropic color film was yielded.

Then the isotropic color film was pasted on one surface of the white plate glass (0050-JFL, produced by Matsunami Glass Ind., Ltd.), to thereby obtain a color film covered glass.

The reflectance of the obtained color film covered glass was measured at an incident angle as shown in Table 1. Results are shown in Table 2. Comparative Example 4 -Isotropic color film, antireflective coating- On one surface of the white plate glass (0050-JFL, produced by 7030

Matsunami Glass Ind., Ltd.), an antireflective layer of MgF2was deposited through vacuum evaporation to obtain an antireflective glass. On the surface of the obtained antireflective glass, which surface is opposite to the side of the antireflective layer, the isotropic color film was pasted. The reflectance of the obtained color film-pasted, antireflective glass was measured at the incident angle as shown in Table 1. Results are shown in Table 3. Comparative Example 5 -Polarizing plate, φ 0 degrees-

On a white plate glass (0050- JFL, produced by Matsunami Glass Ind., Ltd.), a polarizing film was pasted in the same way as in Example 1, such that the angle φ formed by the line intersecting the horizontal reference plane and the base material plane and the high absorption axis of the polarizing film was 0 degrees, to thereby the antireflective glass with a polarizing film was yielded. The reflectance of the resultant antireflective glass with the polarizing film was measured in the same manner as in Example 1, at an incident angle, and at an angle β formed by s-polarized axis of the incident light and the high absorption axis of the polarizing film, as shown in Table 1. Results are shown in Tables 1, 2, and 4. Comparative Example 6 -Polarizing plate, antireflective coating, φ 0 degrees-

On a white plate glass (0050-JFL, produced by Matsunami Glass Ind., Ltd.), a polarizing film was pasted in the same way as in Example 2, such that the angle φ formed by the line intersecting the horizontal reference plane and the base material plane and the high absorption axis of the polarizing film was 0 degrees, to thereby the antireflective glass with a polarizing film was yielded. The reflectance of the resultant antireflective glass with the polarizing film was measured in the same manner as in Example 1, at an incident angle, and at an angle β formed by s-polarized axis of the incident light and the high absorption axis of the polarizing film, as shown in Table 1. Results are shown in Tables 1 and 3.

Comparative Example 7 -Polarizing plate, φ 45 degrees-

On a white plate glass (0050- JFL, produced by Matsunami Glass Ind., Ltd.), a polarizing film was pasted in the same way as in Example 1, such that the angle φ formed by the line intersecting the horizontal reference plane and the base material plane and the high absorption axis of the polarizing film was 45 degrees, to thereby the antireflective glass with a polarizing film was yielded.

The reflectance of the resultant antireflective glass with the polarizing film was measured in the same manner as in Example 1, at an incident angle, and at an angle β formed by s-polarized axis of the incident light and the high absorption axis of the polarizing film, as shown in Table 1. Results are shown in Tables 1 and 4.

09 057030

Table 1

The results in Table 2 indicate that the polarizing plate with 15 degree inclination (Example l) has the lowest average value of reflectance, among the white plate glass (Comparative Example l), the color glass (Comparative Example 3), and the horizontally arranged polarizing plate (Comparative Example 5). Table 3

The results in Table 3 indicate, similar to the results in Table 2, that the polarizing plate with 15 degree inclination (Example 2) has the lowest average value of reflectance even when the antireflective coating was applied. Table 4

The results in Table 4 indicate that when the inclination angle δ is 35 degrees, the polarizing plates with 10 degrees to 35 degrees inclination (Examples 1, 3, 4, and 5) have the lowest average value of reflectance, compared to the case where no polarizing plate is used (Comparative Example 5) or the case where the polarizing plate with 45 degree inclination is used (Comparative Example 7).

It is also clear through the comparison of Examples 1, 3, 4, and 5 that Examples 1, 3, and 5 are preferable because they show the lowest reflectance, that Examples 1 and 3 are more preferable because they have low reflectance at points 5 and 6 which are the region in front of the driver, the region being most important in terms of safety, and that Example 1 is more preferable because it has the lowest reflectance at points 5 and 6. Example 6 <Production of polarizing plate using gold nanorod>

Synthesis of gold nanorods was performed with reference to the Seed-Mediated method [C.J.Murphy et al., J. Phys. Chem. B, 105, 4065 (2001)]. Firstly, 0.25 mL of 0.01 M HAuCU aqueous solution was added to 7.5 mL of

0.1 M cetyltrimethylammoniumbromide (CTAB) (as a surfactant) aqueous solution, and the resultant mixture was stirred for 5 minutes. Then, 0.6 mL of 0.01 M NaBHi aqueous solution as an ice-cooled reducing agent was added at once to the mixture, and the resultant mixture was stirred vigorously for 1 minute. The color of the resultant solution turned from pale yellow to pale brown to yield gold nanoparticles which were seeds of gold nanorods.

Next, 0.032 mL of 0.1 M ascorbic acid aqueous solution was added to a mixed solution of 4.75 mL of 0.1 M CTAB aqueous solution, 0.2 mL of 0.01 M HAuCk aqueous solution, and 0.03 mL of 0.01 M AgNOe aqueous solution, and the mixture was stirred to change the color of the solution from pale brown to transparent. To this reaction solution, 0.01 mL of the above-obtained seed particle solution was added, and the resultant solution was slowly shaken several times for mixing, then allowed to stand for 12 hours, whereby the color thereof changed to reddish purple and gold nanorod aqueous solution was yielded . Since the obtained gold nanorod aqueous solution contained CTAB, purification with an ultracentrifuge was performed. A centrifugation for 12 minutes at 14,000 rpm caused the gold nanorods to sediment. After removing the supernatant fluid, pure water was added to the sediment, and the resultant mixture was centrifuged for 12 minutes at 14,000 rpm. This operation was repeated three times. By removing the supernatant, a concentrated aqueous solution of gold nanorods was obtained.

The resultant concentrated aqueous solution of gold nanorods was subjected to the observation with a transmission electron microscope (TEM) (JEM-2010, produced by JEOL Ltd.). As a result, it was found that the gold nanorods were of nearly equal shape, having a short axis of 12 nm, a long axis of 45 nm, and an aspect ratio of 3.8. -Preparation of gold nanorod-dispersed polyvinylalcohol aqueous solution-

Polyvinylalcohol (PVA-224, produced by Kuraray Co., Ltd.; saponification degree^ 88%; mass average polymerization degree^ 2400) was dissolved in pure water to prepare 7.5% by mass aqueous solution thereof. To a δ g of the polyvinylalcohol aqueous solution was added 2 g of the above gold nanorod aqueous solution, and the mixture was stirred, to thereby yield a polyvinylalcohol aqueous solution in which gold nanorods were stably dispersed. -Preparation of polyvinylalcohol film containing gold nanorods- Next, the gold nanorod-dispersed polyvinylalcohol aqueous solution was applied through a bar coating method onto a polyethylene terephthalate (PET) film, followed by drying for 2 hours at 60°C. The resultant polarized layer was peeled off from the PET film, whereby a polyvinylalcohol film containing gold nanorods and having a dry thickness of 40 μm was obtained. -Extension treatment- The obtained polyvinylalcohol film containing gold nanorods was extended by a factor of 4 with, a uniaxial extender at 90⁰C. A polarizing film displaying isotropic absorption was obtained in which, all the long axis of the gold nanorod was arranged toward the direction of extension. -Orientation of gold nanorods-

A section of the obtained polarizing plate was observed with a transmission electron microscope (TEM) (JEM-2010, produced by JEOL Ltd.). As a result, it was found that 80% by number or more out of 500 gold nanorods was oriented within ±10 degrees with respect to the horizontal plane of the polarizing layer. In addition, 80% by number or more out of 500 gold nanorods was oriented within +10 degrees with respect to direction of extension of the polarizing layer. -Antireflective effect- On a white plate glass (0050- JFL, produced by Matsunami Glass Ind., Ltd.), the obtained gold nanorod polarizing film was pasted in the same way as in Example 1, reflectance was measured at an incident angle and angle β same as in Example 1 shown in Table 1. The results were identical to those of Example 1. Example 7 <Simulation of reflectance> The size of the windshield, and the distance from the driver's eye point to the windshield of CROWN SEDAN produced by Toyota Motor Corporation were used for calculation. A suitable angle of the high absorption axis of the polarizing film with respect to a certain inclination angle was calculated in accordance with the method as described below. In this calculation, a refractive index of the glass was given as 1.52, and the inclination angle δ of the windshield, 7030 the angle φ of the high absorption axis of the polarizing film, the orientation degree S of the polarizing film, and transmission T of the polarizing film were made parameters, and a total of 1512 combinations were adopted as the conditions. As a result, it was found that the scope of the angle φ of the high absorption axis of the polarizing film where the reflection at the driver's seat side was better than a color glass had an upper limit of 42 degrees.

It was also found that the angle φ of the high absorption axis of the polarizing film at which the total reflectance of the whole region of the windshield at a certain inclination angle δ was minimal fell, without exception, within the range of (0.00792 x δ² + 0.0879 δ+14.4) degrees + 5 degrees, as shown in FIG. 5. Moreover, within the range where the total reflectance in the driver's seat side was not stronger than that of color glass at a certain inclination angle δ, the angle φ of the absorption axis of the polarizing film at which angle the reflection from the whole windshield could be most suppressed was found to fall, without exception, within the range (- 0.0130 x δ² + 1.03 δ - 2.46) degrees ± 5 degrees, as shown in FIG. 6.

The method of calculation was as follows.

It is assumed that the windshield of the automobile be a plane, and the point where the driver's line of sight meets vertically the surface of the windshield be the origin 0 (0, 0). Also, the right direction in the driver's view is defined an X-axis direction; the upward direction, as a Y-axis direction; the direction from the origin 0 to the point E (the position of the driver's eye), as a Z-axis direction; the distance between the point E and the origin 0, as 1. It is also defined that when the light enters the windshield at an angle θl, a refracting angle is Θ2, and that the angle formed by the image of incident light to the windshield plane and the 057030 high absorption axis of the polarizing film is α. If the light runs through the polarizing film by a distance equal to the thickness d of the polarizing film applied onto the windshield; and if the light having the electric field components parallel to X-axis, Y-axis, and Z-axis has transmissions for the direction components are respectively tx, ty, and tz, and if the transmission of the windshield base material is 1, the strength of s-wave component is decreased in the time period from the entry of the incident light to the surface of the windshield till the arrival at the back surface of the windshield, in accordance with the following Formula (l).

t^ - tj sin α + r cos a _π , , _x s ^{x y} Formula (1)

The strength of P-wave component is decreased according to the following

Formula (2).

t_P = (t_x ^V∞sθ2 cos² a + 1 sin² a) cos² θ₂ + 1^ sin² θ₂

Formula (2)

Meanwhile, tx, ty, and tz are determined as follows. A measured transmission of the light vertically entering the windshield has a value reflecting a loss due to surface reflection, a loss due to the absorption by the medium, and an extra amount due to the light that is reflected again from the interface. If the incident light is absorbed by the medium when the light runs through the incident surface to the back surface, and if the transmission is defined as t, the reflectance on the surface of inside the automobile, r'; and the reflectance on the outer surface of the automobile, r, then the transmission T when multiple reflection is considered is represented by the following Formula (3). 30

r = (l - r^I)(l - r> + (l - r^!)(l - r)rr7³ + (l - r¹)(l - r)rV² ^⁵ +Λ

Formula (3)

In this formula, the surface reflectances r and r' are determined by using refractive index of the base material n2 or n3 as shown in the following Formulas (4) and (5).

O₁ - W₂)² r = v i 2/ Formula (4)

O₁ - W₃)

O + W₃)²

Formula (5)

Here, r' is determined because the antireflective film is assumed to provide a specific interface which gives a reflection as if the refractive index of the base material is close to the refractive index of air nl, while the refractive angle depends on the actual refractive index of the base material. More specifically, if the antireflective film is applied, it is assumed that the reflectance at the inside surface of the automobile is decreased to a reflectance when the light enters at the incident angle θl into the interface of the base material having a refractive index of n3 (nl <n3 <n2) with air, and the refracting angle is remained as Θ2. Whether such assumption was possible was confirmed by actually measuring the surface reflectance of glass base plate treated with antireflective coating, and comparing the measured values with the calculated values (see FIG. 7, although there is no complete agreement of the performances, they can be assumed to be similar to each other in view of the suppressing effect on the reflectance)

As for a system not using an antireflective film, n3 should be equal to n2. Thus, if the refractive indexes n2 and n3, and transmission T which seems to occur in the measurement with a spectroscope are determined as parameters, t is determined by use of the Formulas (3), (4), and (5).

Here, t is represented by the following Formula (6).

Formula (6)

The orientation degree is represented by the Formula (7)

Formula (7)

In this formula, Ah is the absorbance of the high absorption axis, and Al is the absorbance of the low absorption axis.

From the absorbance and transmission in the Formula (8), the ratio of tx to ty can be determined.

t _ _t (X-S)I(UlS) y ^x Formula (8)

In this calculation, the anisotropy of the absorption is supposed to be uniaxial anisotropy, and determined by the following Formula (9).

t z = t y

Formula (9) As is clear from the above description, transmission performance of the 7030 polarizing film can be determined by the refractive index of the base material, transmission of vertical incident light of the windshield, and the orientation degree.

When θl is not equal to 0, values of the reflectances rS and rP are represented by the Formula (lθ) and (ll), according to Yasuo Kokubu, publisher; Kyoritsu shuppan kabushiki-kaisha, "Sentan (Frontier) Electronics Series 6, Light Wave Engineering",

Formula (10)

tan² (^₁ - ^₂) r_P = tan² (^₁ + ^₂)

Formula (ll)

Given the refractive index nl of air and the refractive index n2 of the base material, θl is related to Θ2 by the SnelT law represented by the following Formula (12).

n_λ ¹ sin θ_λ ¹ = n₀ ² sin θ_? ² F _πormul ,a ( .12) .

If the reflection on both the inner surface of the windshield of the automobile and the outer surface of the windshield of the automobile are considered, reflectance Rs,p is represented by the Formula (13).

2 „ . 2

^1XS,P ^~ " S₅P ^ V- ^ξ S₃P ) ^rS,P ^l, S, Formula (13)

In this formula, r' S,P represent reflectance on the incident plane, and can be obtained by use of the Formulas (lθ) and (ll) using Θ3 obtained by substituting apparent refractive index n3 for n2 in the Formula (12). From the above description, all the necessary materials for calculating the reflectance at each of the points are completed. Firstly, with reference to the size of the windshield, the distance between the eye point of the driver and the windshield, of the CROWN sedan manufactured by Ibyota Motor Corporation, the coordinates for the windshield were determined as nl = 1.00_sn2 = 1.52_^ Iu = 110 cm.. Id = 140 cm_Λh = 65 cn_uel = 60 emu ev = 30 cmu eh = 25 cm.

Here, parameters (inclination angle δ, orientation degree S of the polarizing film, transmission T of the windshield, and apparent refractive index n3 of incident plane) were respectively selected from the ranges, 20 degrees < δ < 50 degrees, 0.6 ≤ S < 1.0, 0.70 < T < 0.85, and 1.1 < n3 ≤ 1.6, by 5 degrees for δ, by 0.05 for S, by 0.05 for T, and by 0.1 for n3, and a total of 1512 combinations were selected to be tested. For each combination, the specific angle φ of the absorption axis of the polarizing film at which the total of reflectance in the driver' seat region was smaller than a color glass having the same transmission was obtained, and it was found that the maximum value was 41.3 degree, and that at an angle smaller than 41.3 degree, the total reflectance of the windshield was smaller in the case where the polarizing film was used than the case where color glass having the same transmission was used.

Moreover, under the same condition, the angle φ of the absorption axis of the polarizing film at which the reflectance of the whole region of the windshield was minimal was determined, and plotted on the coordinates having δ on the axis of abscissa and φ on the axis of ordinates, with the result that each point fell within the range represented by h(δ) min < φ < h(δ) max.

Here, h(δ) min and h(δ) max were respectively defined by the following Formulas (14) and (15), and each of h(δ) min and h(δ) max fell within the range of (0.00792 x 52+ 0.08796 + 14.4) degrees ± 5 degrees.

*(*)_»_ = 0.01085² - 0.1425 + 21.2 _{Formu]a (14)} h(δ)_mia = 0.005015² + 0.3165 + 7.54 ^

Since the driver's eyes are mainly directed to the front of the driver which is in a forward direction of the vehicle, it is preferable to suppress the reflection in this region. Accordingly, the specific angle φ of absorption axis of the polarizing film was determined at which the end (the right end in the case of right handle vehicle) of the driver's side in the windshield shows reflectance same as or lower than that of isotropic color glass, and the total of reflectance of whole region of the windshield is minimal. The values of the angle were plotted on coordinates having abscissa of δ, and ordinate of φ, with the result that all the points fell within the range i(δ)min < φ < i(δ)max.

Here, i(δ)min and i(δ)max are respectively represented by the Formulas (16) and (17), and were in the range of (—0.0130 x δ²+1.03 δ-2.46) degrees ± 5 degrees.

W_™ = -0.0105£² + 0.119S + 4.49 _Formula (16)

- 9.41 Formula (17)

Example 8

<Production of polarizing laminated glass> -Preparation of polyvinyl butyral (PVB) resin- In 1768 g of xylene, 60 g of polyvinyl butyral (PVB) resin having an acetalation degree of 65% by mole was dissolved at 25°C. Then, 95 g of irbutyl aldehyde was added to the solution at one time, and the mixture was sufficiently mixed under stirring for 5 minute, followed by dropping 115 g of 35% by mass aqueous hydrochloric solution for 5 minutes. Thirty minutes after the completion of the mixing thereof, the temperature of the mixture was elevated to 6O⁰C at the rate of 0.5°C/min to 0.6°C/min for 60 minutes. Then, the resultant mixture was left to stand for 3 hours at 60°C, to thereby complete the reaction.

After the completion of the reaction, a mixed solution of water/methanol (mixing ratio; l-l) containing sodium bicarbonate (60% by mass with respect to the solid content of the resin) was excessively added to the reaction mixture. Thereafter, this resin was dropped into an extra amount of methanol and reprecipitated, and the precipitated matter was washed with water and dried, whereby a white powder of polyvinyl butyral resin was yielded. —Preparation of PVB resin film- To 50 g of the polyvinyl butyral, 15 g of triethylene glycol-di-2-ethylbutyrate was added as a plasticizer, and the resultant mixture was thoroughly mixed and kneaded with a mixing roll. Then, 0.08 g of dibutylhydroxytoluene (BHT) was added to the kneaded product as an antioxidant, and a predetermined amount of the resultant kneaded product was retained at 150°C for 30 minutes by a press molding apparatus, whereby a PVB resin film having a thickness of 0.38 mm was yielded. -Preparation of polarizing film-

A polarizing film was prepared in the same manner as in each process of Example 1 except that the polarizing film was not pasted to a glass plate with an adhesive. -Preparation of polarizing laminated glass- Two sheets of the obtained PVB resin films and the polarizing film were piled to obtain a laminated intermediate film having 3 layers, such that the laminated intermediate film had a layered structure of PVB resin film / polarizing film / PVB resin film. This intermediate film was sandwiched between 2 float glasses each of which was a square, 10 cm on a side, and of a thickness of 3 mm, and the resultant sandwich product which was not pressed yet was placed into a rubber bag, and the rubber bag was deaerated at 20 torr vacuum for 20 minutes.

Then, this deaerated bag was transfer to an oven at 90°C, and left to stand at this temperature for 30 minutes. The sandwich product preliminary attached by a vacuum press was then subjected to a thermocompression in an autoclave at a pressure of 12 kg/cm² and at a temperature of 135°C, whereby a polarizing laminated glass was yielded.

Example 9 <Preparation of polarizing laminated glass having ultraviolet absorption performance>

A polarizing laminated glass having an ultraviolet absorption performance was prepared in the same manner as in each process of Example 8 except that

0.08 g of an ultraviolet absorber (TINUBIN PWO, produced by Ciba Geigy) was incorporated concurrently with the incorporation of BHT in the process of producing the PVB resin film.

Example 10

<Preparation of polarizing laminated glass having heat ray shielding performance> -Preparation of heat ray shielding fine particles dispersion plasticizer- 057030

In a horizontal type microbead mill, 15 g of triethylene glycol"di-2-ethylbutyrate as a plasticizer, 6 g of tin doped indium oxide (ITO) fine particles, and 0.6 g of a long-chain alkyl phosphate as a dispersant were placed to disperse the ITO fine particles in the plasticizer, whereby a heat ray shielding fine particle dispersion plasticizer was obtained. The ITO fine particles in the heat ray shielding fine particle dispersion plasticizer had an average particle diameter of 35 nm. -Preparation of laminated glass having heat ray shielding performance-

A polarizing laminated glass having a heat ray shielding performance was prepared in the same manner as in each process of Example 8 except that 20 g of the above-obtained heat ray shielding fine particle dispersion plasticizer was used in place of 15 g of triethylene glycol-di-2-ethylbutyrate in the process of producing the PVB resin film. <Comparison of effect of suppressing unwanted refl.ection> The laminated glasses prepared in the Examples 8 to 10 were arranged on black paper on which gridlike mark was put with a white marker such that each glass formed an angle of 30 degrees to the horizontal plane. The brightness of a white gridlike image reflected on each of the laminated glasses was compared with visual inspection. As a result, it was found that a polarizing laminated glass having an ultraviolet ray absorption performance or a heat ray shielding performance showed reflection brightness completely same as that of a polarizing laminated glass having no such ultraviolet ray absorption performance or a heat ray shielding performance, and therefore found that provision of an ultraviolet ray absorption performance or a heat ray shielding performance do not have a bad influence on the unwanted reflection suppressing effect of the polarizing JP2009/057030 laminated glass.

Industrial Applicability

The windshield for a vehicle of the present invention is suitably used for a windshield for a vehicle such as an automobile in which a driver's seat is placed near the left side or right side if looked at from the front, and which lowers a reflected image of the inner structure of the vehicle reflected from the outer surface of the windshield not only in the plane front view but also in a wider range of the windshield, so as to enhance the safety and the design of the inner structure, and therefore is suitably used in a front glass of an automobile.

Claims

1. A windshield for a vehicle, comprising- a base material, and a polarizing film, wherein the windshield forms an angle δ with a horizontal reference plane, and the angle δ is 20 degrees to 50 degrees, and wherein a line on which the horizontal reference plane intersects with the base material and the high absorption axis of the polarizing film forms an angle φ defined as follows- (-0.0130 x δ² + 1.03 δ - 12.5) degrees ≤ φ < (0.00792 x δ² + 0.0879 δ + 24.4) degrees

2. The windshield for a vehicle according to claim 1, wherein the angle φ is (0.00792 x δ² + 0.0879 δ + 14.4) degrees ± 5 degrees.

3. The windshield for a vehicle according to claim 1, wherein the angle φ is

(-0.0130 x δ² + 1.03 δ - 2.46) degrees ± 5 degrees.

4. The windshield for a vehicle according to any one of claims 1 to 3, wherein the polarizing film is disposed on the face of the base material, facing the horizontal reference plane.

5. The windshield for a vehicle according to any one of claims 1 to 3, wherein the base material is a laminated glass having two glass_^panels and an intermediate layer interposed therebetween, and the intermediate layer contains the polarizing film.

6. The windshield for a vehicle according to any one of claims 1 to 4, wherein the base material is a polymer, and contains the polarizing film either on the surface of or inside of the base material.

7. The windshield for a vehicle according to any one of claims 1 to 6, further comprising an anti-reflection film either on both surfaces of the windshield or the outermost surface of the windshield facing the horizontal reference plane.

8. The windshield for a vehicle according to any one of claims 1 to 7, wherein the vehicle is an automobile.