JP2014177365A - Wind shield for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wind shield for vehicle, which has heat insulation properties and can be fitted to a vehicle body without interference with the use of an apparatus for imaging a vehicle for speeding violation, while a conventional wind shield for vehicle having heat insulation properties reflects or absorbs light on the surface, causing problems in the function of an apparatus for imaging a vehicle for speeding violation for imaging the face of driver through the wind shield in some cases.SOLUTION: The wind shield for vehicle including a heat insulation layer for reflecting or absorbing near infrared rays has a Tmeasured by a method in accordance with ISO 13837 (2008) of 55% or less, and a transmissivity of 20% or more for incident light with an incidence angle of 45 to 65° to a glass surface, in the whole wavelength region of 700 to 800 nm.

Description

  The present invention relates to a window glass for a vehicle having a heat shielding function, and more particularly to a vehicle windshield for which a speed violation vehicle photographing device can be used.

  A glass window provided in front of the driver of a vehicle like an automobile windshield usually has two opposing glass plates and a laminated glass composed of a resin intermediate film sandwiched between them. Used. In particular, as a windshield of an automobile, curved glass having a three-dimensional curvature is widespread from the viewpoint of securing a driver's field of view.

  2. Description of the Related Art In recent years, technology that can reduce the frequency of use of air conditioning equipment such as houses and vehicles has been developed due to increased interest in the environment and energy. Especially in the case of a glass window provided on the front of the vehicle, there are many openings, and the temperature inside the vehicle is likely to rise due to direct sunlight, so the demand for a window glass with heat insulation and heat insulation that reduces the heat load due to sunlight increases. ing. As the window glass having such heat shielding properties and heat insulation properties, those in which a functional film having heat insulation performance and heat insulation performance is pasted on laminated glass and those using an intermediate film containing functional fine particles are known. It has been.

  On the other hand, for the purpose of speed control, a device for photographing a driver's face through a windshield of a speed violation vehicle (see, for example, Patent Documents 1 to 3) has been developed and installed on a public road.

JP-A-57-99627 JP-A-10-269491 JP 2004-334665 A

  When the vehicle windshield having the above-described heat-shielding property is actually mounted on a vehicle body and tested, the light reflected or absorbed by the surface of the vehicle windshield is necessary, and the amount of transmitted light necessary for photographing with a speed violation vehicle photographing device. It has been found that the function of photographing the driver's face through the windshield of the speed violation vehicle photographing device may cause a failure.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to obtain a vehicle windshield that has a heat shielding property but does not hinder the use of a speed violation vehicle photographing device by being attached to a vehicle body.

  A general speed violation vehicle photographing device measures a vehicle speed with a loop coil embedded in a radar or a road, and photographs a vehicle with a film camera or a CCD camera when the vehicle is an overspeed vehicle. At this time, the driver of the traveling vehicle is usually photographed by a camera arranged obliquely in front of the vehicle. On the other hand, when the vehicle windshield is attached to the vehicle body, it is generally attached in an inclined state with respect to the ground. As a result of investigations by the present inventors, it has been found that the failure of the photographing function of the speed violation vehicle photographing device is related to the transmittance of light of a specific wavelength incident on the windshield at a specific angle, and the light transmission It has been found that the wavelength range of transmitted light to increase the rate is different between the case where light incident on the glass surface is incident perpendicularly to the glass surface and the case where the light is incident from a specific angle.

That is, the present invention provides shielding a vehicle window glass having a thermal layer, vehicular glazing ISO13837 (2008) _{T TS} to be measured by a method that conforms to the 55% or less, the incident angle to the glass surface The vehicle windshield is characterized in that the transmittance of incident light of 45 to 65 ° is 20% or more in the entire wavelength region of 700 to 800 nm.

The heat shielding layer may be an intermediate film or glass containing fine particles or components having a heat shielding function, or may be a film having a heat shielding function coated on any surface. The thermal barrier function reflects or absorbs near infrared rays, and the window glass having the functional layer has a total solar transmittance T _TS defined by ISO13837 (2008) of 55% or less. . T _TS is one indicator of the thermal barrier, the T _TS is enough heat shielding function is high low, preferably 50% or less, and more preferably not more than 47%, the lower limit is not particularly necessary to limit , 40% or more is acceptable.

The vehicle windshield is a laminated glass and has a curved surface shape that is bent three-dimensionally. In this invention, the transmittance | permeability and reflectance of each wavelength light, and the transmittance | permeability and reflectance of each wavelength light when the incident angle with respect to a glass surface is 45-65 degrees are incident, the ultraviolet visible spectrophotometer ( V-670 type was measured using a device having a permanently fixed JASCO Corp.) to ARSV-733 type manual stage with absolute reflectance measurement unit, from the obtained values was calculated T _TS.

  As described above, a general speed violation vehicle photographing device is disposed obliquely in front of the vehicle, and photographs the driver's face through the vehicle windshield with the camera of the traveling speed violation vehicle. The incident angle of the light from the camera with respect to the glass surface of the vehicle windshield when performing the above photographing is within a range of 45 to 65 °, which is around 55 ° with respect to the glass surface. all right.

In the vehicle windshield of the present invention, the speed violation vehicle photographing device is normal because the transmittance of incident light with an incident angle of 45 to 65 ° with respect to the glass surface is 20% or more in the entire wavelength region of 700 to 800 nm. Made it possible to work. The upper limit is preferably 30% or more, and the upper limit is preferably 40% or less in order to keep _TTS low.

  In addition, in the vehicle windshield of the present invention, in order to obtain better heat shielding without impeding the use of the speed violation vehicle photographing device, the incident light with respect to the glass surface described above is incident light having an incident angle of 45 to 65 °. On the other hand, the reflectivity at a wavelength exceeding 700 nm and 800 nm or less is less than 20%, the transmittance at a wavelength of 1000 nm or more is 20% or less, and one maximum peak of reflection is present in a range exceeding a wavelength of 800 nm and 1600 nm or less. It is preferable to have the above.

  According to the present invention, it is possible to obtain a vehicle windshield that has heat insulation properties and is attached to the vehicle body and does not hinder the use of the speed violation vehicle photographing device.

The spectrum which shows the transmitted light when the incident angle with respect to the glass surface of Example 1 enters 55 degrees. The spectrum which shows the transmitted light when the incident angle with respect to the glass surface of Example 2 injects 55 degrees. The spectrum which shows the transmitted light when the incident angle with respect to the glass surface of Example 3 injects 55 degrees. The spectrum which shows the transmitted light when normal incidence with respect to the glass surface of the comparative example 1 and light with an incident angle of 55 degrees entered. The spectrum which shows the normal light with respect to the glass surface of the comparative example 2, and the transmitted light when incident light with an incident angle of 55 degrees is incident. The spectrum which shows the transmitted light when the incident angle with respect to the glass surface of the comparative example 3 enters 55 degrees.

The present invention relates to a vehicle window glass having a thermal barrier coating for reflecting or absorbing near infrared rays, vehicular glazing ISO13837 (2008) T _TS to be measured by a method that conforms to the be 55% or less The vehicle windshield is characterized in that the transmittance of incident light having an incident angle with respect to the glass surface of 45 to 65 ° is 20% or more in the entire wavelength region of 700 to 800 nm.

  The vehicle windshield is attached as a windshield obliquely to the vehicle body. According to the study by the present inventors, the wavelength range of transmitted light whose light transmittance should be increased so that photographing with a speed violation vehicle photographing device is possible, the light incident on the glass surface is incident perpendicular to the glass surface. It was found that there is a difference between the case where the light is incident and the case where the light is incident obliquely. This difference in the wavelength region is particularly noticeable among heat-shielding layers, especially in heat-shielding layers that use light interference between layers, such as multilayer films and laminated films, and in laminated films of polarizing liquid crystal layers. I found out that

  And based on such knowledge, the inventor has incident light with a wavelength of 700 to 800 nm when incident light with respect to the glass surface is incident in the range of 45 to 65 °, which is around 55 degrees. It has been found that the above problem can be solved if the windshield has a transmittance of 20% or more in the wavelength region.

  In addition, a vehicle windshield is formed by integrating two or more curved glass plates through an intermediate film which is a resin film for adhesion. The intermediate film may be used singly or two or more intermediate films may be used to sandwich another film or film between the intermediate films.

  When the heat shield layer is formed on the above-described vehicle windshield, the heat shield layer may be formed between the glass and the intermediate film, or may be formed between the intermediate film and the intermediate film. It may be contained inside the intermediate film, or may be a film in which a heat shielding layer is formed on or inside an arbitrary film or substrate and sandwiched between the intermediate films.

  Further, the vehicle windshield is designed so that the visible light transmittance measured by a method according to JIS R3212 is 70% or more from the viewpoint of ensuring the visibility of the driver.

  The vehicle windshield of the present invention has a heat shielding layer that reflects or absorbs the near infrared rays described above between two glass plates. Among the heat shielding layers, the one that reflects near infrared rays has a refractive index of It is possible to use at least one selected from the group consisting of a multilayer film formed by laminating two or more different kinds of thin films, a laminated film of polarizing liquid crystal layers, and a metal film.

  In the case of using a multilayer film in which two or more types of thin films having different refractive indexes are stacked on the heat shield layer, for example, a multilayer film in which high-refractive index oxide films and low-refractive index oxide films are alternately stacked. Or a multilayer film in which two or more types of polymer thin films having different refractive indexes are alternately laminated.

As a multilayer film formed by alternately stacking a high refractive index oxide film and a low refractive index oxide film, TiO ₂ , Nb ₂ O ₅ , Ta ₂ O ₅ , SiO ₂ , Al ₂ O ₃ , ZrO ₂ and two or more oxides selected from the group consisting of MgF ₂ can be used alternately and repeatedly, and the film can be formed by PVD, sputtering, CVD, or the like. it can. Among the oxides, in particular, an infrared ray necessary for a heat shielding effect is formed by using Nb ₂ O ₅ or TiO ₂ for a high refractive index film and using SiO ₂ for a low refractive index film and laminating 4 to 11 layers. It is preferable because it achieves reflectivity and does not impair transparency. The above-mentioned “high refractive index” and “low refractive index” indicate that when two or more kinds of films having different refractive indexes are selected, the higher refractive index is “high refractive index” and the lower refractive index is. Is “low refractive index”.

  A multilayer film formed by alternately laminating two or more polymer thin films having different refractive indexes includes polyethylene terephthalate, polyethylene naphthalate, polymethyl methacrylate, polyethylene, polystyrene, polycarbonate, a mixture of polyvinylidene fluoride and polymethyl methacrylate, A copolymer of ethylene and an unsaturated monocarboxylic acid, a copolymer of styrene and methyl methacrylate, or the like can be suitably used. The number of layers of the polymer thin film is preferably a multilayer film composed of 40 to 1000 layers. When the number is less than 40 layers, the reflectance is small, and when the number exceeds 1000 layers, the reflectance does not increase.

  The polymer thin film can be formed by a melt extrusion method (T-die method, inflation method, etc.), a solution film forming method (coagulation method, casting method, etc.), a calendar method, or the like. Further, for the multilayer formation of the polymer thin film, a co-extrusion method or a lamination method using a T-die method or an inflation method can be suitably used. Furthermore, the multilayer film can be stretched as necessary for the purpose of improving mechanical strength, heat shrinkage characteristics, chemical resistance, transparency and the like.

  There is a film in which a cholesteric liquid crystal phase is fixed as a laminated film of a liquid crystal layer having a polarizing property in a heat shielding layer. Cholesteric liquid crystals can be prepared by blending a nematic liquid crystal with a chiral agent. By adjusting the type of nematic liquid crystal, the type of chiral agent, and the amount of the chiral agent added, it is possible to provide reflection characteristics for the desired reflected light. Can do.

  As a method for producing a heat shielding layer using cholesteric liquid crystal, for example, a necessary amount of a chiral agent is added to nematic liquid crystal so that a desired selective reflection wavelength is expressed. Next, these are dissolved in a solvent, and a photopolymerization initiator is added. Next, this solution is applied onto a plastic substrate such as a PET film, and is left to heat for a certain period of time under such a temperature condition that the nematic liquid crystal becomes a cholesteric liquid crystal and is aligned at a desired helical pitch. Subsequently, the film which comprises a heat-shielding layer is obtained by irradiating an ultraviolet-ray with a high pressure mercury lamp etc. and fixing orientation. The heat shielding layer may be peeled off from the plastic film used as the substrate.

  Any appropriate method can be adopted as a coating method of the heat shielding layer using the cholesteric liquid crystal. Specific examples include a roll coating method, a flow coating method, an ink jet method, a spray coating method, a printing method, a dip coating method, a casting film forming method, a bar coating method, a gravure printing method, and a spin coating method.

  When a metal film is used for the heat shield layer, for example, a metal such as gold, silver, copper, and aluminum can be used. In particular, silver has a high reflectivity and can be preferably used. Form a film.

  As each of the heat shielding layers, a layer in which each film is formed on a substrate may be used. As a kind of base material, what is necessary is just a base material which is easy to follow the curved-surface shape of glass, for example, the heat-shrinkable plastic film is mentioned. If the thickness of the plastic film is about 30 to 200 μm, the generation of wrinkles and the like derived from the curved surface shape of the glass can be suppressed, so that the plastic film can be suitably used. It is preferable that the vehicle windshield be provided with heat insulation by being sandwiched between the film and the film.

  As the plastic film, for example, one plastic film selected from polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polymethyl methacrylate, polyether sulfone, nylon, polyarylate, and cycloolefin polymer is preferably used. In particular, the crystalline polyethylene terephthalate film (PET film) formed by the biaxial stretching method has excellent heat resistance and can be used in a wide range of temperature environments, and is highly transparent and produced in large quantities. Therefore, the quality is stable and suitable.

  As the intermediate film, ethylene vinyl acetate (EVA) or polyvinyl butyral (PVB) is preferably used. Usually, the surface of the intermediate film is subjected to uneven embossing so as not to cause devitrification and bubble defects due to poor deaeration that occurs during integrated processing into laminated glass. Can also be used. In addition, as the intermediate film, a part of which is colored, a sandwiched layer having a sound insulation function, a film having a slope in thickness, or the like can be used.

  Further, the intermediate film may be appropriately blended with an ultraviolet absorber, an antioxidant, an antistatic agent, a heat stabilizer, a colorant, and an adhesion regulator, and particularly those in which fine particles that absorb near infrared rays are dispersed. It can be more preferably used for producing a high-performance heat-shielding laminated glass.

  The vehicle windshield of the present invention has a heat shielding layer that reflects or absorbs the near infrared rays described above between two glass plates. Among the heat shielding layers, those that absorb near infrared rays include near infrared rays. It may have at least one selected from the group consisting of a conductive oxide, metal fine particles, or organic matter to be absorbed between two glasses. It is preferable to have a substance that absorbs near infrared rays between the glasses because the heat shielding function can be improved.

  The material that absorbs near infrared rays is preferably used on the vehicle interior side of the heat shield layer that reflects near infrared rays of the vehicle windshield so that the heat ray reflection by the reflecting layer is not hindered by the absorbing material.

Examples of conductive oxides and metal fine particles that absorb near infrared rays include Sn, Ti, Zn, Fe, Al, Co, Ce, Cs, In, Ni, Ag, Cu, Pt, Mn, Ta, W, V, and At least one metal selected from the group consisting of Mo, oxide, nitride, each single substance doped with Sb or F, or ultrafine particles or lanthanum hexaboride (LaB ₆ ) particles of a conductive material, etc. Is mentioned. In particular, tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), cesium-doped tungsten oxide (CWO), and fluorine-doped tin oxide, which are transparent in the visible light region, have high visible light transmittance and high heat shielding function. Therefore, it is particularly preferable.

  The organic substance that absorbs near infrared rays is not particularly limited, but must satisfy the required optical characteristics and durability. The optimum material includes at least one selected from the group consisting of phthalocyanine compounds, naphthalocyanine compounds, anthracocyanine compounds, and derivatives thereof. Further, a phthalocyanine derivative containing a copper atom or a vanadium atom is particularly preferable in order to further improve the heat shielding property.

  The substance that absorbs near-infrared rays may be dispersed in an interlayer film or glass, or may be coated on the surface of glass, interlayer film, or thermal barrier layer. Since the property is good, it can be preferably used.

  The particle diameter of the fine particles that absorb infrared rays dispersed in the intermediate film is preferably 0.2 μm or less. If it is this size, it can absorb infrared rays while suppressing light scattering in the visible light region, does not generate haze, secures radio wave transparency and transparency, and has adhesiveness, transparency, durability, etc. The physical properties can be maintained at the same level as the unadded interlayer film, and further, the laminated glass can be formed by an operation on a normal laminated glass production line.

  Below, a suitable example of the window glass for vehicles which has the thermal insulation layer which reflects or absorbs near infrared rays of this invention, and the method of producing it is demonstrated.

  First, two soda lime glasses are prepared. The thickness of these glass plates is usually about 2 mmt, but a thickness thinner than this may be used for weight reduction. When a curved surface shape is required as in a windshield, the glass plate is heated and then shaped by pressing with a mold or bending by its own weight so that the two sheets have the same surface shape, and the glass is cooled.

  When a heat shield layer that reflects or absorbs near infrared rays is formed between the intermediate film and the intermediate film, one of the produced glass plates is placed horizontally, and the intermediate film, the heat shield layer, The interlayer films are stacked in order, and the other glass plate is placed at the end. When PVB is used for the intermediate film, it is preferable to maintain the working temperature at constant temperature and humidity in order to keep the moisture content of the intermediate film optimal. An arbitrary film or a substrate on which a heat shield layer is formed may be sandwiched between the intermediate film and the intermediate film. Thereafter, pre-adhesion is performed by heating to a temperature of 80 to 100 ° C. while deaeration of air existing between the glass laminated in the sandwich shape, the intermediate film, and the heat shielding layer. The air can be degassed by wrapping a glass / intermediate film / heat shield layer / intermediate film / glass laminate in a rubber bag made of heat-resistant rubber, or by using a rubber ring only on the edge of the glass. There are two types of ring methods that cover and seal, and either method may be used.

After pre-adhesion is completed, the laminate or the laminate from which the rubber ring has been removed is placed in an autoclave and heated to 120 ° C. to 150 ° C. under a high pressure of 10 to 15 kg / cm ^2. Heat and pressurize for 20 to 40 minutes. After the treatment, after cooling to 50 ° C. or lower, the pressure is released, and the vehicle window glass having a heat shielding layer that reflects near infrared rays is taken out of the autoclave.

  When the thermal barrier layer that reflects or absorbs near infrared rays is formed between the glass and the intermediate film, the same method as described above using the glass or the intermediate film formed with the thermal barrier layer A vehicle window windshield is obtained by the method.

Example 1
A vehicle having a structure of glass / intermediate film / heat shield layer / intermediate film / glass using a film (thickness of about 20 μm) in which a cholesteric liquid crystal phase is fixed to a heat shield film having a heat shield layer reflecting near infrared rays. A window glass was prepared. Note that soda-lime glass (thickness is 2 mm) is used for the outside glass, green heat-absorbing glass (thickness is 2 mm) for the inside glass, and ordinary PVB (thickness) is used for the intermediate film on the outside. 0.38 mm), and PVB (thickness: 0.76 mm) in which ITO fine particles that absorb infrared rays were dispersed was used for the intermediate film inside the vehicle.

When light having an incident angle of 55 ° with respect to the glass surface of the produced vehicle windshield was incident, the transmittance in the entire wavelength region of wavelengths of 700 to 800 nm was 30% or more (FIG. 1). Further, T _TS is 54% calculated from the spectral transmittance and the spectral reflectance when light is incident perpendicularly to the glass surface, the visible light transmittance was 74%.

  The obtained vehicle windshield was assembled to the vehicle body at an attachment angle of 32 °, and the vehicle body was photographed with a speed violation vehicle photographing device attached 3 meters above the ground 34 meters ahead of the vehicle body (in this case, a photographing device for the glass surface) The incident angle of this camera was about 55 °), and a photograph so clear that the driver's face could be identified could be taken.

Example 2
A film mainly composed of silver (thickness: about 100 μm) formed on polyethylene terephthalate by sputtering is used as a heat-shielding film having a heat-shielding layer that reflects near infrared rays, and glass / intermediate film / heat-shielding layer / intermediate film. / Vehicle windshield made of glass was produced. In addition, soda-lime glass (thickness is 2 mm) was used for glass, and normal PVB (thickness was 0.38 mm) was used for the intermediate film.

When light having an incident angle of 55 ° with respect to the glass surface of the manufactured vehicle windshield was incident, the transmittance in the entire wavelength region of wavelengths of 700 to 800 nm was 20% or more (FIG. 2). Incidentally, the T _TS was calculated from the spectral transmittance and the spectral reflectance when light is incident perpendicularly to the glass surface 48% visible light transmittance was 71%.

  The obtained vehicle windshield was assembled to the vehicle body at an attachment angle of 28 °, and the vehicle body was photographed with a speed violation vehicle photographing device attached 6 m above the ground 40 meters ahead of the vehicle body (in this case, a photographing device for the glass surface) The incident angle of this camera was about 55 °), and a photograph so clear that the driver's face could be identified could be taken.

Example 3
Composition of glass / intermediate film / heat shield layer / intermediate film / glass using a film (thickness of about 10 μm) in which CWO fine particles are dispersed on polyethylene terephthalate on a heat shield film having a heat shield layer that absorbs near infrared rays A vehicle windshield comprising: In addition, soda-lime glass (thickness is 2 mm) was used for glass, and normal PVB was used for the intermediate film.

When light having an incident angle of 55 ° with respect to the glass surface of the produced vehicle windshield was incident, the transmittance in the entire wavelength region of wavelengths of 700 to 800 nm was 20% or more (FIG. 3). Incidentally, the T _TS was calculated from the spectral transmittance and the spectral reflectance when light is incident perpendicularly to the glass surface 55%, the visible light transmittance was 73%.

  The obtained vehicle windshield was assembled to the vehicle body at an attachment angle of 31 °, and the vehicle body was photographed with a speed violation vehicle photographing device attached 3 meters above the ground 30 meters ahead of the vehicle body (in this case, a photographing device for the glass surface) The incident angle of this camera was about 55 °), and a photograph so clear that the driver's face could be identified could be taken.

Comparative Example 1
A glass / intermediate film / heat shield layer / intermediate film using a multilayer film (thickness of about 50 μm) in which polyethylene terephthalate and polyethylene naphthalate are alternately laminated on a heat shield film having a heat shield layer that reflects near infrared rays. A vehicle windshield having a membrane / glass configuration was prepared. In addition, soda-lime glass (thickness is 2 mm) is used for the glass on the outside of the vehicle, green heat-absorbing glass (thickness is 2 mm) for the glass on the inside of the vehicle, and ordinary PVB (thickness is 0.2 mm) for the intermediate film. 38 mm) was used.

When light having an incident angle of 55 ° with respect to the glass surface of the manufactured vehicle windshield was incident, the maximum transmittance in the wavelength range of 700 to 800 nm was 64% and the minimum was less than 1% ( FIG. 4). Further, the calculated T _TS from the spectral transmittance and the spectral reflectance when light is incident perpendicularly to the glass surface 62%, the visible light transmittance was 82%. In addition, the transmittance | permeability in all the wavelength ranges of wavelength 700-800 nm when light injects perpendicularly with respect to the glass surface was 60% or more.

  The obtained vehicle windshield was assembled to the vehicle body at an attachment angle of 32 °, and the vehicle body was photographed with a speed violation vehicle photographing device attached 3 meters above the ground 34 meters ahead of the vehicle body (in this case, a photographing device for the glass surface) The incident angle of the camera was about 55 °), and the image that passed through the windshield was not clearly visible, and the driver's face could not be identified.

Comparative Example 2
A vehicle having a structure of glass / intermediate film / heat shield layer / intermediate film / glass using a film (thickness of about 20 μm) in which a cholesteric liquid crystal phase is fixed to a heat shield film having a heat shield layer reflecting near infrared rays. A window glass was prepared. Note that soda-lime glass (thickness is 2 mm) is used for the outside glass, green heat-absorbing glass (thickness is 2 mm) for the inside glass, and ordinary PVB (thickness) is used for the intermediate film on the outside. 0.38 mm), and PVB (thickness: 0.76 mm) in which ITO fine particles that absorb infrared rays were dispersed was used for the intermediate film inside the vehicle.

When light having an incident angle of 55 ° with respect to the glass surface of the produced vehicle windshield was incident, the maximum transmittance in the wavelength range of 700 to 800 nm was 45% and the minimum was less than 5% ( FIG. 5). Further, T _TS is 54% calculated from the spectral transmittance and the spectral reflectance when light is incident perpendicularly to the glass surface, the visible light transmittance was 76%. In addition, the transmittance | permeability in all the wavelength ranges with a wavelength of 700-800 nm when light injected into a glass surface perpendicular | vertical was 40% or more.

  The obtained vehicle windshield was assembled to the vehicle body at an attachment angle of 28 °, and the vehicle body was photographed with a speed violation vehicle photographing device attached 6 m above the ground 40 meters ahead of the vehicle body (in this case, a photographing device for the glass surface) The incident angle of the camera was about 55 °), and the image that passed through the windshield was not clearly visible, and the driver's face could not be identified.

Comparative Example 3
A windshield for a vehicle having a glass / intermediate film / glass configuration was prepared using PVB (thickness: about 0.8 μm) in which CWO fine particles absorbing near infrared rays were dispersed in the intermediate film. As the glass, green heat-absorbing glass (thickness: 2 mm) was used.

When light having an incident angle of 55 ° with respect to the glass surface of the manufactured vehicle windshield was incident, the maximum transmittance in the wavelength range of 700 to 800 nm was 37% and the minimum was less than 15% ( FIG. 6). Incidentally, T _TS 53% calculated from the spectral transmittance and the spectral reflectance when light is incident perpendicularly to the glass surface, the visible light transmittance was 71%.

  The obtained vehicle windshield was assembled to the vehicle body at an attachment angle of 31 °, and the vehicle body was photographed with a speed violation vehicle photographing device attached 3 meters above the ground 30 meters ahead of the vehicle body (in this case, a photographing device for the glass surface) The incident angle of the camera was about 55 °), and the image that passed through the windshield was not clearly visible, and the driver's face could not be identified.

Claims (3)

A window glass for a vehicle having a thermal barrier layer which reflects or absorbs near infrared rays, T _TS vehicular window glass, as measured by a method conforming to ISO13837 (2008) is not more than 55%, for a glass surface A vehicle windshield characterized in that the transmittance of incident light with an incident angle of 45 to 65 ° is 20% or more in the entire wavelength region of 700 to 800 nm. A vehicle window in which the heat shielding layer has at least one selected from the group consisting of a multilayer film in which two or more kinds of thin films having different refractive indexes are laminated, a laminated film of a liquid crystal layer having polarization properties, and a metal film. shield. The vehicle windshield according to claim 1 or 2, wherein at least one selected from the group consisting of a conductive oxide, a metal fine particle, or an organic substance that absorbs near infrared rays is provided between two glasses.

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