WO2006112529A1

WO2006112529A1 - Windshield with antifogging layer and automobile employing said windshield

Info

Publication number: WO2006112529A1
Application number: PCT/JP2006/308488
Authority: WO
Inventors: Hideki Ishioka; Tetsuji Irie; Akira Hirano
Original assignee: Asahi Glass Company, Limited
Priority date: 2005-04-18
Filing date: 2006-04-18
Publication date: 2006-10-26
Also published as: JP2008536732A

Abstract

Antifogging property and visibility is improved while maintaining low cost. A windshield 101 to be employed for a window of a cabin of moving vehicle (automobile 100), which includes one area 101a functioning as a main eye range area for a passenger, and another area 101b neighboring to said one area 101a. The antifogging performance in said another area is more excellent than the antifogging performance of said one area. Further, in said another area, an antifogging function is preferably provided on a surface on the cabin side of the windshield. Further, the main eye range area is preferably the specific defrost area A or C according to Japanese Industrial Standards (JIS D4501).

Description

DESCRIPTION

WINDSHIELD WITH ANTIFOGGING LAYER AND AUTOMOBILE EMPLOYING SAID WINDSHIELD

5 TECHNICAL FIELD

The present invention relates to a windshield and an automobile employing it, in particular, to a windshield more excellent in antifogging property and visibility than those of conventional windshields, and an automobile o employing such a windshield.

BACKGROUND ART

Heretofore, various attempts have been made to a windshield for automobiles to prevent deterioration of

15 visibility due to dew condensation. Examples of such attempts include a defroster for clearing a fogging due to dew condensation by blowing a heated air against a front glass, an electric heated glass (refer to JP-A- 2004-268770 and JP-A-2000-128588) having a plurality of

20 fine heat strips embedded in an inter layer and a hydrophilic antifogging layer (refer to Japanese Patent No. 3150133) formed on a cabin side of a windshield. Here, the antifogging layer in the present invention does not mean one on which no fogging is formed, but one on

25 which fogging is reduced. For example, the antifogging layer includes an antifogging layer on which forming of fogging becomes slower., However, there have been various problems such that use of such a defroster for a long time raises the temperature of the cabin excessively, and use of such an electric heated glass consumes a large amount of electric power to cause deterioration of gasoline mileage. For these reasons, the above measures are not suitable for recent development of automobiles considering environmental problems. To cope with this problem, an attempt has been made to prevent forming of fogging by forming an antifogging layer on the entire surface on the cabin side of the windshield.

Methods of reducing fogging of a windshield by an antifogging layer, include a water film method of forming a hydrophilic film, a water repellent method of forming a hydrophobic film, and a water absorption method of imparting a water-absorbing property by a porous film. However, each of these known methods has a problem when it is used for a windshield for automobiles .

In the water film method, the method causes a certain degree of distortion of view even if a water film is uniformly formed. Accordingly, in the case of using the water film method for automobiles, it is necessary to suppress the distortion within a degree of not causing a problem of visibility for drivers. Further, at the same time, there is a problem that it is necessary to add a function of draining moisture condensed into a water film and falling along a windshield. In the water repellent method, this method is suitable for dropping a large droplet such as rain since the contact angle is large. However, in order to remove fine droplets such as fogging, a film having an additional function different from conventional repellent technique, is required.

In the water absorption method, a water film (fogging) is formed on a surface of a water-absorbing film if the amount of water exceeds the water-absorbing capacity of the water-absorbing film. The water film formed on the surface of water-absorbing film, is hard to be dried by e.g. a defroster. This is because the water film formed on the surface of water-absorbing film is constituted by fine water droplets, and a large amount of water is present in the water-absorbing film and its vicinity. As a result, there is a problem that once such a water film is formed, visibility tends to be deteriorated for a long time.

Namely, if a known antifogging film is used for imparting antifogging function to a windshield for automobiles particularly to its main eye range area for passengers, there is a possibility that visibility for drivers is prevented depending on characteristics or performances of the film or conditions for use. Therefore, means for solving these new problems need to be added to conventional techniques, and such requirement increases technical difficulty. Further, there is a new problem that such an antifogging film itself increases a haze value of the windshield, and decreases the visibility.

Furthermore, such an antifogging film to be formed on the cabin side of the windshield is generally- expensive. Accordingly, forming such a film on a large area such as a windshield for automobiles, causes to increase the production cost of automobiles.

The present invention is to solve these problems, and it is an object of the present invention to provide a windshield which is inexpensive and more excellent in antifogging property and visibility than those of conventional windshields, and to provide an automobile employing such a windshield.

DISCLOSURE OF THE INVENTION

In order to achieve the above objects, the present invention provides a windshield to be used for a window for a cabin of a moving vehicle, the windshield comprising one area functioning as a main eye range area for a passenger and another area neighboring to said one area, wherein said another area has an antifogging performance more excellent than the antifogging performance of said one area. Further, an embodiment of the present invention includes the following construction. Namely, in said another area, a surface in the cabin side of the windshield has an antifogging function .

Further, the present invention provides a windshield to be used for a window of a cabin of a moving vehicle, the windshield comprising in its front view at least the following three areas comprising a first area functioning as a main eye range area for a passenger, and second and third areas present in the left and right sides respectively of the first area and neighboring to the first area, wherein in the second and third areas, the surface of the cabin side on the windshield has an antifogging function.

Further, an embodiment of the present invention includes the following construction. Namely, the second and third areas are connected to each other by a band- shaped area extending along an upper edge or a lower edge of the windshield or band-shaped regions extending along the upper edge and the lower edge, in the front view, and in each of the band-shaped areas, the surface in the cabin side of the windshield is provided with an antifogging function. Further, the main eye range area is the specific defrost area C according to Japanese Industrial Standards (JIS D4501) or the specific defrost area C according to Japanese Industrial Standards (JIS D4501) . Further, the main eye range area is an area having an outline shifted inwardly by a predetermined distance from the outline of the specific defrost area A according to Japanese Industrial Standards (JIS D4501) . Further, the antifogging function is exerted by making the windshield comprise an antifogging layer or an antifogging film. Further, the windshield comprises a plurality of types of antifogging layers or a plurality of types of antifogging films. Further, at least one antifogging layer consists essentially of a water absorption resin layer. Further, the windshield comprises a water repellent layer on a part or all of a surface on the external side of the windshield opposite from the cabin.

Further, the present invention provides an automobile comprising any one of the above windshields, and a defroster for blowing heated air against the main eye range area on the cabin side of the windshield. The present invention includes one area functioning as a main eye range area for passengers, and another area neighboring to said one area, and the antifogging property of said another area is more excellent than the antifogging property of said one area. By such a construction, no antifogging layer having unnecessarily large areal size is required, and a windshield and an automobile employing the windshield can be provided at low cost. Further, in such a windshield, only a main eye range area needs to be an electric heated glass, and it is not necessary to provide the entire windshield with heat strip. Accordingly, power consumption is reduced to significantly contribute to energy saving. Further, in a case where a defroster is used in combination with such a windshield, since only fogging in the main eye range area needs to be cleared, only a small amount of heated air is required. Accordingly, it is possible to clear a problem that the cabin temperature unnecessarily rises. Further, even if e.g. an antifogging layer or film is scratched or discolored and exfoliated by ultraviolet rays, visibility through the main eye range area is not significantly affected. This is because no such layer or film is present in the main eye range area and thus, the visibility for drivers is not extremely deteriorated. Further, it is apparent that the present invention is suitable for a so-called panoramic-shaped windshield. Here, a panoramic-shaped windshield means a windshield having such a shape that both sides of the windshield extend more backwards than the position of the existing front pillar, or a windshield having such a shape that the windshield and a roof glass are integrally formed.

BRIEF EXPLANATION OF THE DRAWINGS

Figs. 1 (a) , 1 (b) and l(c) are front views showing an example of a windshield according to the present invention. Fig. 2 is an explanation view showing a part of automobile employing the windshield of Fig. 1.

Fig. 3 is a cross-sectional view along a line III - III ' of Fig . 2 .

Figs. 4 (a) , 4 (b) , 4 (c) and 4 (d) are front views showing other embodiments of the windshield according to the present invention. Figs. 5 (a) and 5 (b) are front views showing other embodiments of the windshield according to the present invention.

Fig. 6 (a) is a front view showing an embodiment of a panoramic shape . Fig. 6 (b) is a cross-sectional view along a line VIb - VIb' of Fig. 6 (a) .

Fig. 6 {c) is a front view showing another example of the panoramic shape .

BEST MODE FOR CARRYING OUT THE INVENTION

Then, an embodiment of the present invention will be described.

Figs. l(a) to 1 (c) are plan views showing an embodiment of the present invention. As shown in Fig. 1 (a) , a windshield 101 for automobiles is, in the front view, constituted by an area 101a as a specific defrost area A according to Japanese Industrial Standards (JIS D4501) , and an area 101b as the rest of the windshield. On the cabin side surface of the windshield 101, an antifogging treatment is provided. The area to be provided with the antifogging treatment is preferably the area 101b as the area of the windshield other than the area 101a since the visibility of windshield 101 may be affected in such an area. Here, in most types of automobiles, the specific defrost area A is expected to be within an area defined by an upper limit present between 250 and 350 mm from the top edge, side limits present between 80 and 170 mm from side edges and a lower limit present between 120 and 280 mm from the bottom edge of the windshield.

Accordingly, the antifogging layer is formed or a film containing an antifogging resin (hereinafter referred to as an antifogging resin film) is laminated only in an area of the cabin side of the windshield 101 other than the area 101a (namely, in the area 101b) . In order to clear the fogging formed in the area 101a, a defroster is used which is positioned to blow heated air approximately only in the area, or an electric heated glass is employed in which a heating body is provided only in the area 101a. By such a construction, it is possible to solve problems such as rising of cabin temperature or a consumption of a large amount of energy that are problems of conventional techniques.

Further, no e.g. antifogging layer is provided in the area 101a remarkably influencing visibility. Accordingly, even if e.g. an antifogging layer in the area 101b is scratched or discolored or defoliated by ultraviolet rays, visibility in the main eye range area is hardly affected and. visibility for drivers is not extremely prevented. Here, besides the above construction, entire or at least a part of the external side of the windshield 101 may be provided with a water repellent layer. On the other hand, the area 101a does not necessarily coincide with the specific defrost area A as a standard for defrosters. For example, as shown in Fig. 1 (b) , the area may be set so that its edges are shifted inwardly by predetermined distances from corresponding edges of the specific defrost area A. Fig. 1 (b) shows an example in which the area is shifted by a distance A from the left side edge, a distance B from the bottom edge, a distance C from the left edge, and a distance D from the top edge. The distances A to D are determined specifically according to e.g. a computer simulation test using e.g. a computer, or e.g. a driving test using a test automobile. Further, when a type of automobile is e.g. a bus or a truck, the construction may be such that as shown in Fig. 1 (c) , areas 101d are set at the specific defrost areas C according to Japanese Industrial

Standards (JIS D4501) , wherein no e.g. antifogging layer is provided.

Here, a specific method for antifogging treatment is described. A chemical is prepared by dissolving a solid component having antifogging function into a solvent. The chemical is applied on a glass plate and dried by evaporating the solvent to form an antifogging layer on the surface of the glass plate. Here, the process may be such that an antifogging resin film that is a transparent or a colored resin film on which an antifogging layer is formed, is prepared, and the antifogging resin film is laminated on the glass plate.

Further, the antifogging layer may be a water absorption resin layer or a hydrophilic layer. The water absorption resin layer exerts antifogging function by absorbing moisture in the air or moisture adsorbed to the surface of the layer to prevent forming of water droplets at the surface of the layer, and the hydrophilic layer exerts antifogging function by reducing the contact angle of water adhered to the layer surface to about at most 10° to form a water layer to thereby prevent forming of water droplets. Here, in the hydrophilic layer, water adsorbed to the surface forms a water film. Thus, the view is distorted when the water film becomes thick. For this reason, the antifogging layer to maintain excellent visibility, is preferably a water absorption resin film not forming a water film. The water absorption resin film is, for example, obtained by dissolving polyacrylic ester and epoxy in an alcohol, and applying thus obtained solution on a glass surface and drying it by heating. Further, the method for forming the antifogging layer is not limited to a particular method, but may be optionally selected from known coating methods such as a dip coating method, a spray coating method, a spin coating method, a nozzle flow coating method, coating method with brush or combination of these methods. Since the area to form the antifogging layer, is only a part of the cabin side of the windshield, a masking by e.g. a masking tape may be applied to the area not to form the antifogging layer, or else, after applying the antifogging treatment to the entire surface of the glass, an area other than the area to form the antifogging layer, may be polished to remove the antifogging layer. Further, the method is not particularly limited to the above methods .

Further, the antifogging layer may have an underlayer such as SiO₂ for increasing durability. The underlayer may be formed by applying the material by wet coating using a sol-gel method. Further, the antifogging layer may be formed by dry coating using a sputtering method or a CVD method. The antifogging layer and the antifogging resin film is preferably completely transparent from the viewpoint of visibility. However, they may be colored to an extent not deteriorating visibility. Further, in a case where an antifogging resin is laminated to a film, an adhesive agent may be employed for making the film closely in contact and fixed to a glass. The type of adhesive agent is not particularly limited, but from the viewpoint of visibility, it is preferably completely transparent.

Then, an embodiment of an automobile employing the windshield according to the present invention, will be described.

Fig. 2 is an explanation view showing a part of an automobile employing the windshield of Fig. 1. Further, Fig. 3 is a cross-sectional view along a line III - III' of Fig. 1. As shown in these figures, an automobile 100 is constituted by various types of interior members and structural members. Namely, the automobile 100 around the driver seat, is constituted by a windshield 101, a dashboard 102, an instrument panel 103, a defroster (the main unit of the defroster is not shown, and a nozzle for blowing a heated air is installed in an area 104), a steering wheel 105, a mirror base 106, a room mirror 107, a roof 108, a cowl 109, an engine hood 110, a cowl louver 111, a defroster main unit 112 etc.

Here, the steering wheel 101 is installed between a driver seat (not shown) and the instrument panel 103, and is used by a driver when an automobile is operated. In the instrument panel 103, various types of indicators (not shown) are installed at positions visible from the driver, and the instrument panel 103 is integrally formed with the dashboard 102 made of a resin. Further, in the vicinity of the upper edge of the windshield 101, the room mirror 107 is attached via the mirror base 106 fixed to the roof 107 (Fig. 3) . Further, the bottom edge of the windshield 101 is adhered and fixed to the cowl 109, and the cowl louver 111 is attached so as to cover the cowl 109 to prevent e.g. intrusion of rainwater.

The windshield 101 shown in Fig. 2 and Fig. 3, is one shown in Fig. 1. An area 101b in a cabin side surface, is provided with an antifogging function by e.g. an antifogging layer or an antifogging film. On the other hand, in an area 101a, a glass surface is exposed to the air as it is, and is provided with no antifogging function that is applied to the area 101b. Further, a nozzle for blowing a heated air from the defroster main unit 112, is provided in any position in a broken line area 104 shown in the exterior side from the dashboard 102 or the instrument panel 103.

For example, the number and the shape of the nozzle in the area 104 may be appropriately selected. For example, a plurality of nozzles may be installed or a large sized nozzle may be installed at the center in the front view of the windshield 101. In any case, in order to clear fogging formed in the windshield 101 only by a defroster until fogging in every corner is cleared, it is necessary to blow a heated air to the entire area of the windshield 101. This is not preferred from the viewpoint of energy saving or controlling the cabin temperature. The size and the installation position of the defroster should be considered so that heated air is mainly blown to the area 101b provided with no antifogging function.

Here, the area provided with no antifogging layer nor antifogging film, is not necessarily accurately coincide with the specific defrost area A (the area 101a of Fig. 1) , and it may be a larger area including the specific defrost area A. For example, as shown in Fig. 4 (a) , an area 201a provided with no e.g. antifogging layer, may be extended to the lower edge of a windshield 201. Namely, a windshield 201 may be employed, which has a construction that e.g. an antifogging layer is provided only in areas 201b along left and right front pillars (not shown) and a roof (not shown) , and no e.g. antifogging layer is provided in the area 201a as the rest of the windshield. Further, as shown in Fig. 4 (b) , a windshield 301 may be employed, which has a construction that e.g. an antifogging film is provided only in areas 301b along left and right front pillars (not shown), and no e.g. antifogging layer is provided in an area 301a as the rest of the windshield.

Further, as shown in Fig. 4 (c) , a windshield 401 may be employed, which has a construction that e.g. an antifogging layer is provided only in areas 401b along left and right front pillars (not shown), and no e.g. antifogging layer is provided in an area 401a as the rest of the windshield. Here, in this case, no antifogging layer is provided in an area having an outline shifted inwardly from that of the specific defrost area A by a predetermined distance. By such a construction, a main eye range area becomes an area narrower than the specific defrost area A, but as > shown in Fig. 4 (c) , center side edges of left and right antifogging layers can be made in parallel with each other. Such a shape of antifogging layer has a merit that it is easily formed by coating the windshield in a direction shown by an arrow E when the layer is formed by coating.

Further, as shown in Fig. 4 (d) , a windshield 501 may be employed, which has a construction that instead of the specific defrost area A, an area 501a including the specific defrost area C according to Japanese Industrial Standards (JIS D4501) is used as a main eye range area, and e.g. an antifogging layer is provided in areas 501b as the rest of the windshield. Such a windshield is particularly suitable for e.g. a bus or a truck. Here, the shape of such an antifogging layer has also a merit that it is easily formed by coating the windshield in the direction of an arrow F when the layer is formed by coating.

The above description describes constructions in which an antifogging layer or an antifogging film having a single performance is provided in areas other than the main eye range area, and no antifogging layer or antifogging film is provided in the rest of the windshield. However, e.g. a plurality of types of antifogging layers having different antifogging performances may be employed in combination. For example, as shown in Fig. 5 (a) , a windshield 601 may be constituted by an area.601 provided with no e.g. antifogging layer, an area 601b neighboring to the area 601a and provided with an antifogging layer having a weak antifogging performance, and further, an area 601c provided with an antifogging layer having stronger antifogging performance than that of the area 601b.

Further, as shown in Fig. 5 (b) , a windshield 701 may be constituted by an area 701a provided with no e.g. antifogging layer, an area 701b neighboring to the area 701a and provided with an antifogging layer having a weak antifogging performance, and further, an area 701c provided with an antifogging layer having stronger antifogging performance than that of the area 701b. By gradually changing antifogging performance, it is possible to prevent a border line between the eye range area and the area provided with e.g. antifogging layer, from showing up by fogging. Here, as evident from Fig. 5 (b) , the windshield 701 has a merit that it is easily producible by forming each antifogging layer by coating the windshield in the direction of an arrow G. Fig. 6 (a) and Fig. 6 (c) are e.g. front views showing an embodiment of a panoramic shape suitable for a minivan type automobile. As shown in Fig. 6 (a) , the windshield 801 is mainly constituted by an area 801a as a visual area and an area 801b in the outer periphery of the area 801a, provided with a dark ceramic layer. The entire shape of the windshield 801 is such that in its front view, the windshield is broaden from its top edge towards the bottom edge, and an area called overhang is formed in the bottom side. Specifically, the length of a line on a glass surface connecting the center of a contour line along the glass surface connecting meeting points where left and right edges respectively meet the bottom edge, and the center of the bottom edge, is defined as a bottom side overhang OH.

Further, as shown in Fig. 6 (b) , the length of a line connecting the center of the contour line along the surface of the glass (corresponding to an arc) connecting the meeting points where left and right edges of the windshield respectively meet the bottom edge, and the center of a shortest line connecting the meeting points, is defined as an arc depth D. Further, the minimum value of the curvature radius of the arc in the vicinity of the side edges, is defined as a minimum wing R. Accordingly, the panoramic shape is defined as a shape satisfying that a value of arc depth D [mm] x bottom side overhang OH [mm] is from 60,000 to 180,000 (preferably from 100,000 to 160,000) , and a minimum wing R [mm] is from 100 to 1,000.

In a windshield having the panoramic shape thus defined, an antifogging layer is provided in areas 812 (areas hatched by upward sloping lines) present in the left and right sides of border lines passing through points 810 as meeting points where the upper edge meets left and right edges respectively when the windshield 801 is observed from the front. In the area 811 as the rest of the windshield, no antifogging layer is provided or even if an antifogging layer is provided, a layer having lower antifogging performance than that of the area 812, is preferably provided. Here, Fig. 6 (c) shows an example of a windshield having a larger bottom side overhang OH than those of conventional examples, which is also included in the present invention. Further, since the panoramic shape is determined depending on the e.g. the type of automobile (e.g. sedan, wagon or minivan) , the shape and the size, it is apparent that the panoramic shape is not limited to the above example. For example, a windshield having such a panoramic shape that the top side of the windshield is extended to the position of entire roof or a part of the roof of an existing automobile, is also included in the present invention.

INDUSTRIAL APPLICABILITY

As described above, the present invention is suitable for a case where it is desired to eliminate the possibility of deterioration of visibility due to distortion of view, discoloring or defoliation in a main eye range area. Further, it is apparent that the present invention can be applied to not only a windshield for automobiles, but also a window glass used for moving vehicles such as trains, ships or airplanes, or buildings. Further, for such a windshield, instead of a glass plate, a resin plate made of e.g. polycarbonate, may be employed. Further, automobiles according to the present invention include those of various types such as sedans, wagons, minivans, RVs, buses, trucks, motorcycles, etc.

Claims

1. A windshield to be used for a window for a cabin of a moving vehicle, the windshield comprising one area functioning as a main eye range area for a passenger and another area neighboring to said one area, wherein said another area has an antifogging performance more excellent than the antifogging performance of said one area .

2. The windshield according to Claim 1, wherein in said another area, a surface in the cabin side of the windshield has an antifogging function.

3. A windshield to be used for a window of a cabin of a moving vehicle, the windshield comprising in its front view at least three areas comprising a first area functioning as a main eye range area for a passenger, and second and third areas present in the left and right sides respectively of the first area and neighboring to the first area, wherein in the second and third areas, the surface on the cabin side of the windshield has an antifogging function.

4. The windshield according to Claim 3, wherein the second and third areas are connected to each other by a band-shaped area extending along an upper edge or a lower edge of the windshield or band-shaped regions extending along the upper edge and the lower edge, in the front view, and in each of the band-shaped areas, the surface on the cabin side of the windshield is provided with an antifogging function.

5. The windshield according to any one of Claims 1 to 4 , wherein the main eye range area is the specific defrost area C according to Japanese Industrial Standards (JIS D4501) or the specific defrost area C according to Japanese Industrial Standards (JIS D4501) .

6. The windshield according to any one of Claims 1 to 4 , wherein the main eye range area is an area having an outline shifted inwardly by a predetermined distance from the outline of the specific defrost area A according to Japanese Industrial Standards (JIS D4501) .

7. The windshield according to any one of Claims 2 to 6 wherein the antifogging function is exerted by making the windshield comprise an antifogging layer or an antifogging film.

8. The windshield according to Claim 7, which comprises a plurality of types of antifogging layers or a plurality of types of antifogging films.

9. The windshield according to Claim 8 wherein at least one antifogging layer consists essentially of a water absorption resin layer.

10. The windshield according to any one of Claims 1 to 9, which further comprises a water repellent layer formed on a part or all of a surface on the external side of the windshield opposite from the cabin.

11. An automobile comprising a windshield as defined in any one of Claims 1 to- 10, and a defroster for blowing a heated air against the main eye range area on the cabin side of the windshield.