JP7510963B2 - Laminated Glass - Google Patents

Description

The present invention relates to laminated glass.

On cold days or in cold regions, automobile windshields can fog up, making driving difficult. For this reason, various methods have been proposed for removing fog from windshields. For example, Patent Document 1 discloses a method in which a bus bar and a heating wire are placed inside the windshield, and the heat generated by these wires is used to remove fog.

JP 2016-143450 A

The windshield is formed of laminated glass in which a bus bar and an adhesive layer are placed between two glass sheets. When producing this laminated glass, the bus bar is placed on the adhesive layer, and then these are sandwiched between two glass sheets and pressure is applied to bond them together. However, a step is created between the bus bar and the adhesive layer, and there is a risk that air will remain in this step during bonding. If such air remains, it will be visible as bubbles in the completed laminated glass, resulting in a decrease in product quality. The generation of such bubbles is not limited to bus bars, but can also be a problem when a functional layer, such as an infrared reflective film or a light control film, is sandwiched between two glass sheets.

The functional layer can be formed so that its outer edge coincides with the outer edge of the glass plate. In this way, the above-mentioned step does not occur, and the generation of bubbles can be prevented. However, in this case, the outer edge of the functional layer is exposed between the glass plates, and water may enter between the glass plates from this point. If the laminated glass swells, the original function of the laminated glass may be lost. In addition, there is the following problem. That is, since the edge of each glass plate may be formed in an arc-shaped cross section, if the outer edge of the functional layer coincides with the outer edge of the glass plate, the adhesive layers may not adhere to each other, which may cause wrinkles in the adhesive layer and the functional layer. Therefore, by positioning the outer edge of the adhesive layer toward the center from the position of the outer glass position (for example, about several mm to 30 mm), the intrusion of water can be prevented. However, if the outer edge of the adhesive layer is positioned inside the outer edge of the glass plate in this way, the above-mentioned bubbles may be generated.

The present invention has been made to solve the above problems, and aims to provide laminated glass in which a functional layer is disposed between two glass sheets, thereby improving the visual quality.

Item 1: An outer glass sheet having a first side and a second side opposite to the first side;
An inner glass plate arranged opposite the outer glass plate and having substantially the same shape as the outer glass plate;
an interlayer disposed between the outer glass sheet and the inner glass sheet;
a shielding layer formed on a surface of the outer glass sheet;
Equipped with
The intermediate film is
An adhesive layer;
A functional layer supported by the adhesive layer;
Equipped with
At least a part of the outer periphery of the functional layer has an inner portion located inside the outer periphery of the adhesive layer,
The shielding layer is arranged to cover at least the area between an inner portion of the functional layer and an outer peripheral edge of the adhesive layer.

Item 2: The laminated glass of item 1, in which the shielding layer is located on the surface of the outer glass sheet facing the interlayer film.

Item 3: The laminated glass according to item 2, further comprising a second shielding layer provided on the surface of the inner glass sheet opposite the intermediate film.

Item 4: The laminated glass according to any one of items 1 to 3, in which the shielding layer is formed around the entire outer peripheral edge of the outer glass sheet.

Item 5: The laminated glass according to any one of items 1 to 4, wherein the shielding layer is disposed between the outer glass sheet and the interlayer film.

Item 6: The laminated glass according to any one of items 1 to 5, wherein the thickness of the functional layer is 5 to 200 μm.

Item 7: The functional layer is
a first bus bar at least a portion of which extends along the end of the first side;
a second bus bar at least a portion of which extends along the end of the second side;
a plurality of heating wires arranged to connect the first bus bar and the second bus bar;
Equipped with
a part of an outer circumferential edge of the first bus bar and a part of an outer circumferential edge of the second bus bar constitutes the inner portion,
Item 7. The laminated glass according to any one of items 1 to 6, wherein the shielding layer is formed so as to cover both bus bars and the vicinity of their peripheral edges.

Item 8: The functional layer further has a support layer that supports both the bus bars and the heating wire,
Item 8. The laminated glass according to item 7, wherein the support layer is in contact with the adhesive layer.

Item 9: The laminated glass described in item 7 or 8, wherein both bus bars are formed by laminating multiple metal layers.

Item 10: The laminated glass according to any one of items 7 to 9, wherein the pitch of the heating wires is 1.25 to 4 mm.

Item 11: The laminated glass according to any one of items 7 to 10, wherein the heat generated by the heating wire is 2.0 W/m or less.

Item 12: The laminated glass according to any one of items 7 to 11, wherein the thickness of the heating wire is 30 μm or less.

Item 13: The laminated glass according to any one of items 7 to 12, wherein the width of the surface of the heating wire on the adhesive layer side is 1 to 30 μm.

Item 14: The voltage applied to both bus bars is less than 20 V;
The width of the surface of the heating wire on the adhesive layer side is equal to or greater than the thickness of the heating wire,
Item 14. The laminated glass according to any one of items 7 to 13, wherein the heating line has a width of 9 to 20 μm.

Item 15: The voltage applied to both bus bars is 20 to 50 V,
The width of the surface of the heating wire on the adhesive layer side is equal to or greater than the thickness of the heating wire,
Item 14. The laminated glass according to any one of items 7 to 13, wherein the width of the heating line is 1 to 10 μm.

The laminated glass of the present invention can improve the appearance quality even when a functional layer is placed between two glass sheets.

1 is a front view of one embodiment of laminated glass according to the present invention. 2 is a cross-sectional view taken along line AA in FIG. 1. FIG. 2 is a diagram showing an example of a heating wire. FIG. 2 is a side view of a furnace through which the mold passes. FIG. 1 is a photograph taken near the bus bar of Reference Example 1. 13 is a photograph taken near the bus bar of Reference Example 2. 13 is a photograph taken near the bus bar of Reference Example 3. 13 is a photograph taken near the bus bar of Reference Example 4. 1 is a table showing the specifications of the heating wires according to Reference Examples 5 to 16. 1 is a table showing the specifications of the heating wires according to Reference Examples 17 to 27. FIG. 2 is a front view showing another example of the laminated glass of FIG. 1 . FIG. 2 is a front view showing another example of the laminated glass of FIG. 1 .

An embodiment in which the laminated glass according to the present invention is applied to a windshield will be described below with reference to the drawings. FIG. 1 is a plan view of the windshield according to this embodiment, and FIG. 2 is a cross-sectional view of FIG. 1. As shown in FIGS. 1 and 2, the windshield according to this embodiment comprises an outer glass sheet 1, an inner glass sheet 2, and an intermediate layer 3 disposed between these glass sheets 1 and 2. In addition, notches 21 and 22 are formed at the upper and lower ends of the inner glass sheet 2, respectively, and connecting members 41 and 42 extending from the intermediate layer 3 are exposed in each of the notches 21 and 22. Each component will be described below.

<1. Overview of laminated glass>
<1-1. Glass plate>
Each of the glass plates 1 and 2 is formed in a rectangular shape with the lower side 12 longer than the upper side 11. That is, it is formed in a trapezoid shape surrounded by the upper side 11, the lower side 12, and both sides (left side 13, right side 14). As described above, the upper end and the lower end of the inner glass plate 2 are each formed with an arc-shaped notch. Hereinafter, the notch formed at the upper end of the inner glass plate 2 will be referred to as the first notch 21, and the notch formed at the lower end will be referred to as the second notch 22. In addition, as each of the glass plates 1 and 2, a known glass plate can be used, and they can be formed of heat absorbing glass, general clear glass, green glass, or UV green glass. However, these glass plates 1 and 2 need to realize a visible light transmittance in accordance with the safety standards of the country in which the automobile is used. For example, the outer glass plate 1 can ensure the necessary solar radiation absorptance, and the inner glass plate 2 can adjust the visible light transmittance to meet the safety standards. Below are shown examples of compositions of clear glass, heat absorbing glass, and soda-lime glass.

(Clear glass)
_SiO2 : 70 to 73% by mass
_Al2O3 : _0.6 to 2.4 mass%
CaO: 7 to 12% by mass
MgO: 1.0 to 4.5% by mass
R ₂ O: 13 to 15 mass % (R is an alkali metal)
Total iron oxide calculated as Fe ₂ O ₃ (T-Fe ₂ O ₃ ): 0.08 to 0.14 mass%

(Heat absorbing glass)
The composition of the heat ray absorbing glass can be, for example, based on the composition of clear glass, with the ratio of total iron _{oxide (T-Fe2O3 ) converted} to _Fe2O3 being 0.4 to 1.3 mass%, the ratio of _CeO2 being 0 to 2 mass%, the ratio of _TiO2 being 0 to 0.5 mass%, and the glass skeletal components (mainly _{SiO2 and Al2O3} ) being reduced by the increases in T _{- Fe2O3} , _CeO2 and _TiO2 .

(Soda-lime glass)
_SiO2 : 65 to 80% by mass
_Al2O3 : ₀ to 5 mass%
CaO: 5 to 15% by mass
MgO: 2% by mass or more NaO: 10 to 18% by mass
_K2O : 0 to 5% by mass
MgO + CaO: 5 to 15% by mass
_Na2O + _K2O : 10 to 20% by mass
_SO3 : 0.05 to 0.3 mass%
_B2O3 : ₀ to 5% by mass
Total iron oxide calculated as Fe ₂ O ₃ (T-Fe ₂ O ₃ ): 0.02 to 0.03 mass%

As described above, each glass plate 1, 2 is formed in a rectangular shape, but the ratio of the length of the upper side 11 to the lower side 12 can be, for example, 1:1.04 to 1:1.5. For example, if the upper side is 1200 mm, the lower side can be 1250 to 1800 mm. Specifically, the upper side can be 1195 mm and the lower side can be 1435 mm. Note that the ratios described above are the ratios in a two-dimensional plane when the windshield is projected from the front.

In other words, although Figure 1 shows an example in which the bottom edge 12 is long, it can also be applied to a windshield with a long top edge 11. For example, if the top edge of a windshield for a compact one-person vehicle is 500 mm, the bottom edge can be 350 to 450 mm. Specifically, the top edge can be 500 mm and the bottom edge 425 mm.

The thickness of the laminated glass according to this embodiment is not particularly limited, but from the viewpoint of weight reduction, the total thickness of the outer glass sheet 1 and the inner glass sheet 2 is preferably 2.4 to 4.6 mm, more preferably 2.6 to 3.4 mm, and particularly preferably 2.7 to 3.2 mm. Thus, in order to reduce weight, it is necessary to reduce the total thickness of the outer glass sheet 1 and the inner glass sheet 2, so the thickness of each glass sheet is not particularly limited, but the thickness of the outer glass sheet 1 and the inner glass sheet 2 can be determined, for example, as follows:

The outer glass sheet 1 must be durable and impact resistant against external obstacles. For example, if this laminated glass is used as a windshield for an automobile, it must be impact resistant against flying objects such as pebbles. On the other hand, the greater the thickness, the heavier it becomes, which is undesirable. From this perspective, the thickness of the outer glass sheet 1 is preferably 1.0 to 3.0 mm, and more preferably 1.6 to 2.3 mm. The thickness to be adopted can be determined depending on the application of the glass.

The thickness of the inner glass sheet 2 can be the same as that of the outer glass sheet 1, but can be made thinner than the outer glass sheet 1, for example, to reduce the weight of the laminated glass. Specifically, taking into account the strength of the glass, it is preferably 0.6 to 2.0 mm, more preferably 0.8 to 1.8 mm, and particularly preferably 0.8 to 1.6 mm. Furthermore, it is preferably 0.8 to 1.3 mm. The thickness to be adopted for the inner glass sheet 2 can also be determined according to the application of the glass.

When the heating wire 314 included in the intermediate layer 3 described later is disposed at the center in the thickness direction of the intermediate layer 3, the thicknesses 1 and 2 of the two glass plates may be different. Which glass plate is made thicker depends on the main use of the heating wire 314.

The outer glass sheet 1 and the inner glass sheet 2 according to this embodiment may have a curved shape. However, when each of the glass sheets 1 and 2 has a curved shape, it is said that the sound insulation performance decreases as the overlap amount increases. The overlap amount is an amount that indicates the bending of the glass sheet, and when a straight line L is set connecting the center of the upper side and the center of the lower side of the glass sheet, the longest distance between this line L and the glass sheet is defined as the overlap amount D.

In addition, for curved glass sheets, when the overlap amount is in the range of 30 to 38 mm, there is no significant difference in sound transmission loss (STL: Sound Transmission Loss), but compared to flat glass sheets, it is clear that the sound transmission loss is lower in the frequency band of 4000 Hz or less. Therefore, when producing curved glass sheets, it is preferable that the overlap amount is small. Specifically, it is preferable that the overlap amount is less than 30 mm, more preferably less than 25 mm, and particularly preferably less than 20 mm.

Here, an example of a method for measuring the thickness of a curved glass plate is described. First, the measurement positions are two points, one above and one below, on a center line that runs vertically through the center of the glass plate in the left-right direction. The measuring device is not particularly limited, but for example, a thickness gauge such as the SM-112 manufactured by Techlock Corporation can be used. When measuring, the curved surface of the glass plate is placed on a flat surface, and the edge of the glass plate is clamped with the thickness gauge to perform the measurement.

<1-2. Middle class>
Next, the intermediate layer 3 will be described. The intermediate layer 3 is composed of three layers including a heat generating layer 31 and a pair of adhesive layers 32, 33 that sandwich the heat generating layer 31 and have the same shape as the glass plates 1, 2. Hereinafter, the adhesive layer disposed on the outer glass plate 1 side will be referred to as the first adhesive layer 32, and the adhesive layer disposed on the inner glass plate 2 side will be referred to as the second adhesive layer 33.

The heating layer 31 includes a number of heating wires 314, as described below, which remove snow, ice, and fog that form on the surface of the windshield. On the other hand, the heat generated by the heating wires 314 heats the surrounding adhesive layers 32, 33, etc., which can cause flickering when looking outside the vehicle through the windshield. Thus, the heating wires 314 are required to generate a heat output that can melt ice, etc., while also preventing flickering. For this reason, in this embodiment, the dimensions of the heating wires 314, such as the heat output, line width, and pitch, are set as described below.

As a result of the inventor's research, it was found that in order to prevent flickering when looking outside the vehicle through the windshield, it is necessary to keep the temperature of the heating wire 314 and its surroundings at 60° C. or less. To achieve this, it is necessary to reduce the amount of heat generated by the heating wire 314 to a certain extent. The amount of heat generated can be calculated by the following formula (1). The relationship between the resistance of the heating wire 314 and the length and cross-sectional area of the heating wire 314 is given by formula (2).
W = IV = ^RI2 = ^V2 / R (1)
R = ρ(L/A) (2)
Where W: power, E: voltage, I: current, R: resistance, L: length, A: cross-sectional area, ρ: electrical resistivity

Therefore, based on the above formulas (1) and (2), measures can be taken to reduce the amount of heat generated, such as increasing the resistance R, increasing the length L of the heating wire 314, decreasing the cross-sectional area A of the heating wire 314, and increasing the electrical resistivity ρ. On the other hand, a certain amount of heat is required for melting ice, etc. Therefore, if the amount of heat generated by each heating wire 314 decreases, it is necessary to increase the number of heating wires 314 in order to maintain the amount of heat generated by the entire windshield. Taking the above points into consideration, the various components that make up the intermediate layer 3 will be described below.

<1-2-1. Heating layer>
First, the heating layer 31 will be described. The heating layer 31 includes a sheet-like substrate (support layer) 311, a first bus bar 312, a second bus bar 313, and a plurality of heating wires 314 arranged on the substrate 311. The plurality of heating wires 314 are connected in parallel so that both bus bars 312, 313 serve as electrodes. The substrate 311 can be formed in a rectangular shape to correspond to the glass plates 1, 2 and the adhesive layers 32, 33, but it does not necessarily have to be the same shape as the adhesive layers 32, 33, and may be smaller than both glass plates 1, 2 (in this case, for example, the portion on the periphery of the substrate 311 that is inside the periphery of the glass plate corresponds to the inner portion of the present invention). For example, as shown in FIG. 1, the vertical direction can be shorter than the length between both notches 21, 22 so as not to interfere with the notches 21, 22 of the inner glass plate 2. The length of the substrate 311 in the horizontal direction can also be shorter than the width of both glass plates 1, 2.

<1-2-1-1. Busbar>
The first bus bar 312 is formed to extend along the upper side of the base material 311. On the other hand, the second bus bar 313 is formed to extend along the lower side of the base material 311, but is formed to be longer than the first bus bar 312. However, each bus bar 312, 313 is disposed inside the notches 21, 22 so as not to be exposed from the notches 21, 22 when the intermediate layer 3 is sandwiched between the glass plates 1, 2. The vertical width of each bus bar 312, 313 is preferably, for example, 5 to 50 mm, and more preferably 10 to 30 mm. This is because if the width of the bus bars 312, 313 is smaller than 5 mm, the amount of heat generated by the bus bars increases, which reduces the amount of heat generated by the heating wire 314, and the desired amount of heat cannot be obtained. On the other hand, if the width of the bus bars 312, 313 is greater than 50 mm, the bus bars 312, 313 may protrude from the shielding layer 7, obstructing the field of view. Also, the bus bars 312, 313 do not have to be formed precisely along the substrate 311. In other words, they do not have to be completely parallel to the edge of the substrate 311, and may be curved.

The busbars 312 and 313 can be formed in a single layer or multiple layers. For example, an additional member formed in a strip shape similar to the busbars 312 and 313 can be formed and layered on the busbars 312 and 313. This increases the thickness of the busbars 312 and 313, making it possible to keep the resistance value low. As a result, heat generation in the busbars 312 and 313 can be suppressed. The material of the additional member is preferably the same as that of the busbars 312 and 313, so that the additional member and the busbars 312 and 313 can be integrated when they are layered. The additional member can be fixed to the busbars 312 and 313 by, for example, solder, but is not limited to this.

The heating wires 314 are formed to extend in the vertical direction so as to connect both bus bars 312 and 313. The heating wires 314 are arranged generally parallel to each other. Each heating wire 314 can be formed in a straight line or in various shapes such as a wave shape. In particular, by forming each heating wire 314 in a sine wave shape, the heat distribution becomes uniform and the heating wire 314 can be optically prevented from obstructing the field of view of the windshield. In this case, the crimp ratio of the heating wire 314 can be set to, for example, 150% or less. The crimp ratio is the ratio of the actual length of the heating wire 314 (the length following the curve) to the length between both ends of the heating wire 314 on the heat generating layer 31. By setting the crimp ratio in this way, it is possible to increase L in formula (2). As a result, the resistance R increases, the amount of heat generated decreases, and flickering can be suppressed. In the drawing, the heating wire 314 is drawn in a straight line, but it can also include a wave shape as described above.

<1-2-1-2. Heating wire>
The width of each heating line 314 is preferably 1 to 30 μm, more preferably 5 to 20 μm, and particularly preferably 8 to 15 μm. However, if the width of the heating wire 314 is reduced, the cross-sectional area is also reduced, which may result in a reduced amount of heat generation, as described above. Therefore, the lower limit of the line width of the heating wire 314 can be set as described above. On the other hand, if the line width of the heating wire 314 is large, it becomes easier to see, and the amount of heat generated increases due to the increase in the cross-sectional area. The upper limit of the line width of the heating line 314 is set as described above.

However, depending on the voltage applied between the two bus bars 312 and 313, the width can be set as follows. For example, when the voltage is less than 20 V, the width of the heating wire 314 is preferably 7 to 30 μm. By setting the width to 7 μm or more, the cross-sectional area becomes larger and the amount of heat generated increases. In other words, even when the voltage is less than 20 V, the required amount of heat generated (for example, 400 W/ ^m2 or more) can be achieved. On the other hand, by setting the width to 30 μm or less, the visibility can be reduced and the amount of heat generated per heating wire 314 can be suppressed, and as a result, flickering can be prevented. From the viewpoint of flickering, the width of the heating wire 314 is preferably 20 μm or less, and more preferably 15 μm or less.

When the voltage applied between the bus bars 312, 313 is 20 to 50 V, the line width is preferably 1 to 10 μm. By making the line width 1 μm or more, the amount of heat generated can be increased. On the other hand, by making the line width 10 μm or less, visibility can be reduced. Note that this line width refers to the line width of the largest part of the cross-sectional shape of the heating wire 314. For example, when the cross-sectional shape of the heating wire 314 is a trapezoid, the line width is the width of the bottom side, and when the cross-sectional shape of the heating wire 314 is a circle, the line width is the diameter.

The thickness of the heating wire 314 is preferably 30 μm or less, more preferably 20 μm or less, and particularly preferably 10 μm or less. As the thickness is reduced, the step between the heating wire 314 and the substrate 311 is reduced, and as described below, it is possible to suppress the generation of bubbles near this step during manufacturing. In addition, the thickness of the heating wire 314 is preferably smaller than the line width of the heating wire 314. In other words, it is preferable that the aspect ratio of the cross section of the heating wire 314 is 1 or less. This is because if the thickness is greater than the line width of the heating wire 314, for example, the heating wire 314 may collapse on the substrate 311, making manufacturing difficult, or there is a risk of wire breakage.

On the other hand, as mentioned above, a thinner thickness of the heating wire 314 is preferable to suppress the generation of bubbles, but in order to achieve the required amount of heat generation, it is preferable to increase the thickness of the heating wire 314 and increase its cross-sectional area. From this perspective, the thickness of the heating wire 314 is preferably 5 μm or more, although there is a possibility of bubbles generating. Also, as will be described later, if the thickness of the heating wire 314 is 10 μm or more, there is a greater possibility of bubbles generating. However, if the amount of heat generated per heating wire 314 becomes too high, there is a risk of flickering, so as mentioned above, it is desirable for the thickness to be 30 μm or less.

The line width and thickness of the heating wire 314 can be measured using a microscope such as the VHX-200 (manufactured by Keyence Corporation) at 1000x magnification.

The pitch between adjacent heating wires 314 is preferably 1.25 to 4.0 mm, more preferably 1.50 to 3.5 mm, and even more preferably 2.0 to 3.0 mm. Note that the pitch does not refer to the length of the gap between adjacent heating wires 314, but refers to the length of the gap between adjacent heating wires 314 plus the line width of the heating wire 314.

By setting the upper limit of the pitch in this way, for example, when a predetermined heat generation amount (e.g., 400 W/ ^m2 ) is required for the entire windshield, even if the heat generation amount W of each heating wire 314 is reduced as described above, the pitch can be reduced and the number of heating wires 314 can be increased, so that the reduction in the heat generation amount for the entire windshield can be prevented. On the other hand, as of November 2017, there is the following provision in Japan regarding the lower limit of the pitch. That is, Article 39, paragraph 3, item 5 (window glass) of the notification prescribing the details of the safety standards for road transport vehicles prescribes that, among the devices for preventing fogging of window glass, those embedded in the test area A "shall have a width of 0.03 mm or less and a density of 8 wires/cm or less (5 wires/cm when the conductor is embedded horizontally)." However, in order to satisfy the requirement of 8 wires/cm or less, it is desirable that the pitch be 1.25 mm or more. In addition, when the heating wires 314 are formed in a sine wave shape, for example, as shown in Fig. 3, the distance L between the center lines of each heating wire 314 becomes the pitch of the heating wires 314. In this case, the distance L between the center lines D of the waves of adjacent heating wires 314 can be set to be twice or more the amplitude A of each heating wire 314. In addition, the amplitude A is not particularly limited, but can be, for example, 3 mm or more.

The lower limit of the pitch of the heating wire 314 is also considered in the following respect. That is, it has been found that if the pitch is small, the above-mentioned bubbles are more likely to occur. Specifically, it has been found that if the pitch is smaller than 1.25 mm, bubbles are more likely to remain. Also, if bubbles occur on the periphery of the busbars 312 and 313, the bubbles can be hidden by the shielding layer described below, but if bubbles occur on the periphery of the heating wire 314, they cannot be hidden. For this reason, the pitch of the heating wire is preferably 1.25 mm or more, and more preferably 2.0 mm or more.

Even if the pitch of the heating wire 314 is increased to suppress the generation of bubbles, bubbles are likely to remain at the edge of the heating wire 314, for example, at the intersection of the side of the heating wire 314 and the substrate 311. In response to this, for example, it is preferable to form the substrate 311 from PVB, since the bubbles may dissolve in the PVB. However, not all bubbles dissolve, and the bubbles that do not dissolve may move along the heating wire 314 to the busbars 312, 313 and remain on the periphery of the busbars 312, 313. Therefore, considering the behavior of such bubbles, it is meaningful to cover the busbars 312, 313 with the shielding layer 7.

The heating wires 314 may be formed in a sine wave shape. The positions of the sinusoidal unevenness may differ between adjacent heating wires 314, or the pitch of the unevenness may differ. In these cases, the pitch of the heating wires 314 may be determined by counting the number n of heating wires 314 in a specified area. For example, if the specified area is a rectangular area with sides of 200 mm, and 101 heating wires 314 are arranged in the area, the pitch can be determined as 200/(101-1) = 2 mm. The specified area is preferably within the range of the test area A defined in JIS R3212. This is because the test area A in JIS R3212 is an area for performing tests such as perspective distortion, and there is a high need to prevent flickering, which is the effect of the present application, in that area.

The length of the heating wire 314 can be, for example, 1000 mm or more. Alternatively, it can be 1100 mm or more, or 1200 mm or more. Furthermore, the resistance of the heating wire 314 is preferably 30 Ω or more, and more preferably 90 Ω or more. By lengthening the length of the heating wire in this way, the resistance R increases based on formula (2), so the amount of heat generated decreases and flickering can be suppressed.

Here, the measurement of the resistance R of the heating wire 314 will be described. The measurement can be performed using a commercially available electrical resistance measuring instrument, and an example is the 73200 series digital multimeter (manufactured by YOKOGAWA). When performing the measurement, first, the heating wire to be measured is selected. Next, one terminal of the electrical resistance measuring instrument is connected to the vicinity of the bus bar 312 of the heating wire, and the other terminal is connected to the vicinity of the bus bar 313 of the heating wire. In addition, as shown in FIG. 1, if the heating wire is sandwiched between the outer glass plate 1 and the inner glass plate 2 and the terminal of the electrical resistance measuring instrument cannot be connected to the heating wire, the outer glass plate 1 or the inner glass plate 2 can be destroyed to measure the resistance R of the heating wire 314. In addition, for example, when the heating wire to be measured and the heating wire adjacent to it are connected by a bridge (not shown), the resistance R of the heating wire to be measured is measured after cutting the bridge.

In addition, the heat generation amount per unit length of each heating wire 314 is preferably 2.0 W/m or less, more preferably 1.5 W/m or less, and particularly preferably 1.0 W/m or less, when a voltage of, for example, 13.5 V or 48 V is applied between both bus bars 312 and 313. When the heat generation amount is 2.0 W/m or less, flickering can be suppressed. More specific ranges can be, for example, 1.5 W/m or more to 2.0 W/m or less, 1.35 W/m or more to 1.5 W/m or less, 1.20 W/m or more to 1.35 W/m or less, 1.0 W/m or more to 1.20 W/m or less, 0.8 W/m or more to 1.0 W/m or less, or 0.5 W/m or more to 0.8 W/m or less. In order to effectively perform defogging, de-icing, etc., when using such heating wire 314, the heat generation amount per unit area of the windshield is preferably 300 to 600 W/ ^m2 , more preferably 400 W/ ^m2 or more, and particularly preferably 500 W/ ^m2 or more.

<1-2-1-3. Heating layer material>
Next, the material of the heating layer 31 will be described. The base material 311 is a transparent film that supports both bus bars 312, 313 and the heating wire 314. The material is not particularly limited, and may be, for example, polyethylene terephthalate, polyethylene, polymethyl methacrylate, polyvinyl chloride, polyester, polyolefin, polycarbonate, polystyrene, polypropylene, nylon, or the like. Alternatively, it may be made of polyvinyl butyral resin (PVB), ethylene vinyl acetate (EVA), or the like. The bus bars 312, 313 and the heating wire 314 may be made of the same material, and may be made of various materials such as copper (or tin-plated copper), gold, aluminum, magnesium, cobalt, tungsten, silver, or alloys of these metals. Among these, it is particularly preferable to use silver, copper, gold, or aluminum, which are materials with electrical resistivities of 3.0×10 ⁻⁸ Ωm or less. When the electrical resistivity of the heating wire 314 is reduced in this way, the resistance R is reduced based on the formula (2), and the amount of heat generated tends to increase. However, flickering can be suppressed by adjusting the pitch, length, cross-sectional area, and line width of the heating wire 314.

Next, a method for forming the bus bars 312, 313 and the heating wire 314 will be described. The bus bars 312, 313 and the heating wire 314 may be directly printed on the glass plates 1, 2 with a conductive material, as long as the width of the bus bars 312, 313 and the heating wire 314 is 10 μm or more. In this case, the glass plate can be directly heated to form the heating wire, that is, the intermediate film does not need to be heated when the heating wire 314 is formed, so that the intermediate film can be deformed and the occurrence of perspective distortion can be suppressed. The heating wire 314 can also be formed by arranging a preformed thin wire (wire, etc.) on the substrate 311, but in particular, to make the width of the heating wire 314 thinner, the heating wire 314 can be formed by forming a pattern on the substrate 311. The method is not particularly limited, and various methods such as printing, etching, and transfer can be used to form the heating wire 314. At this time, the bus bars 312, 313 and the heating wire 314 can be formed separately, or they can be formed integrally. Note that "integral" means that there is no gap (seamless) between the materials and no interface exists.

In addition, both bus bars 312, 313 are formed on the substrate 311, and the substrate 311 corresponding to the bus bars 312, 313 is peeled off and removed, leaving the substrate 311 for the heating wire 314. After that, a heating wire can be placed on the substrate between the two bus bars.

In particular, when etching is employed, the following can be used as an example. First, a metal foil is dry laminated on the base material 311 via a primer layer. For example, copper can be used as the metal foil. Then, by performing a chemical etching process using a photolithography method on the metal foil, both bus bars 312, 313 and a plurality of heating wires 314 can be integrally patterned on the base material 311. In particular, when the line width of the heating wire 314 is made small (for example, 15 μm or less), it is preferable to use a thin metal foil, and a thin metal layer (for example, 5 μm or less) may be formed on the base material 311 by deposition or sputtering, and then patterning may be performed by photolithography. The surface of the heating wire 314, that is, the surface on the inner glass plate 2 side, is blackened, which makes it possible to suppress the heating wire 314 from being visible from the inside of the vehicle. Materials for blackening include copper nitride, copper oxide, nickel nitride, nickel chrome, etc., and these materials can be used to perform blackening by plating.

<1-2-2. Adhesive layer>
The adhesive layers 32 and 33 are sheet-like members for sandwiching the heat generating layer 31 and adhering it to the glass plates 1 and 2. Although the adhesive layers 32 and 32 are formed to have the same size, the adhesive layers 32 and 32 each have a cutout portion of the same shape at a position corresponding to the cutout portion 21 and 22 of the inner glass plate 2. These adhesive layers 32 and 33 can be made of various materials, for example, polyvinyl butyral resin (PVB), ethylene vinyl acetate (EVA), etc. In particular, polyvinyl butyral resin is This is preferable because it has excellent adhesion to the glass plate and excellent resistance to penetration. A layer of a surfactant may be provided between the adhesive layers 32 and 33 and the heat generating layer 31. This can modify the surfaces of both layers and improve the adhesive strength.

In addition, as described above, when the base material 311 is formed smaller than the adhesive layers 32, 33, the peripheries of the adhesive layers 32, 33 are bonded together. Since the same materials bond easily to each other, the heat generating layer 31 can be firmly held between the adhesive layers 32, 33. However, the shapes of the adhesive layers 32, 33 are not particularly limited, and they can be smaller than the glass plates 1, 2.

The intermediate film 3 can have other configurations. For example, the base material 311 of the heat generating layer 31 is not provided, and the bus bars 312, 313 and the heating wire 314 can be formed between the two adhesive layers 32, 33. The base material 311 may have a high haze rate depending on the material, which may reduce the transmittance of the laminated glass. Therefore, by not providing the base material 311, the transmittance of the laminated glass can be increased. In addition, either one of the adhesive layers 32, 33 may be used. Therefore, for example, the intermediate film 3 can be composed of one adhesive layer, the bus bars 312, 313, and the heating wire 314. When the adhesive layer is one, for example, when the first adhesive layer 32 is eliminated, the heating wire 314 comes into contact with the outer glass sheet 1. In this case, it is suitable for removing ice and snow from the outer glass sheet 1. On the other hand, when the second adhesive layer 33 is eliminated, the heating wire 314 comes into contact with the inner glass sheet 2. In this case, it is suitable for removing the fogging that occurs on the inner glass sheet 2. Additionally, as mentioned above, additional materials can be stacked on the busbars 312 and 313 to increase the thickness of the busbars 312 and 313.

The thickness of the additional member is not particularly limited, but since it is used to reduce the resistance value of the bus bars 312 and 313, the thickness can be determined accordingly. For example, it can be 50 to 200 μm (e.g., 100 μm). However, when an additional member is used, the above-mentioned bubbles are more likely to occur.

<1-2-3. Thickness of intermediate layer>
The total thickness of the intermediate layer 3 is not particularly specified, but is preferably 0.3 to 6.0 mm, more preferably 0.5 to 4.0 mm, and particularly preferably 0.6 to 2.0 mm. The thickness of the base material 311 of the heat generating layer 31 is preferably 5 to 200 μm, and more preferably 5 to 100 μm. The provision of the base material 311 may also cause the generation of bubbles as described above.

On the other hand, the thickness of each adhesive layer 32, 33 is preferably larger than the thickness of the heat generating layer 31, specifically, 0.05 to 2.0 mm is preferable, and 0.05 to 1.0 mm is even more preferable. Furthermore, although details will be described later, considering the ease of heat dissipation from the heating wire 314 to the glass plates 1, 2, it is preferable that the thickness of each adhesive layer 32, 33 is small, specifically, 0.05 to 0.4 mm is preferable. The thicknesses of both adhesive layers 32, 33 may be the same or different. When heat dissipation is taken into consideration, for example, the thickness of the first adhesive layer 32 can be 30 to 70 μm (for example, 50 μm) and the thickness of the second adhesive layer 33 can be 500 to 900 μm (for example, 760 μm). In this case, since the thickness of the first adhesive layer 32 is small, the heat from the heating wire 314 is easily transmitted to the outer glass plate 1, and the defrosting performance is improved. On the other hand, if the thickness is reversed between the first adhesive layer 32 and the second adhesive layer 33, the heat from the heating wire 314 is more easily transferred to the inner glass plate 2, improving the anti-fogging performance. In order to bring the second adhesive layer 33 and the base material 311 into close contact with each other, it is preferable that the thickness of both bus bars 312, 313 and the heating wire 314 sandwiched therebetween is 3 to 20 μm, taking this into consideration.

The thicknesses of the heat generating layer 31 and the adhesive layers 32, 33 can be measured, for example, as follows. First, a cross section of the laminated glass is displayed at 175 times magnification using a microscope (for example, Keyence VH-5500). The thicknesses of the heat generating layer 31 and the adhesive layers 32, 33 are then visually identified and measured. At this time, in order to eliminate variability due to visual inspection, the measurements are made five times, and the average value is taken as the thickness of the heat generating layer 31 and the adhesive layers 32, 33.

The thickness of the heat generating layer 31 and adhesive layers 32, 33 of the intermediate layer 3 does not need to be constant over the entire surface, and can be wedge-shaped, for example, for laminated glass used in head-up displays. In this case, the thickness of the heat generating layer 31 and adhesive layers 32, 33 of the intermediate layer 3 is measured at the thinnest point, that is, the bottom edge of the laminated glass. When the intermediate layer 3 is wedge-shaped, the outer glass plate 1 and the inner glass plate 2 are not arranged parallel to each other, but such an arrangement is also included in the glass plate of the present invention. In other words, the present invention includes an arrangement of the outer glass plate 1 and the inner glass plate 2 when an intermediate layer 3 using a heat generating layer 31 and adhesive layers 32, 33 whose thickness increases at a rate of change of 3 mm or less per meter is used.

<1-3. Connection material>
Next, the connecting material will be described. The connecting materials 41 and 42 are for connecting each bus bar 312 and 313 to a connecting terminal (anode terminal or cathode terminal: not shown), and are formed in a sheet shape from a conductive material. A voltage higher than 12 V, for example, a power supply voltage of 13.5 V, is applied to this connecting terminal. In the following, the connecting material connected to the first bus bar 312 will be referred to as the first connecting material 41, and the connecting material connected to the second bus bar 313 will be referred to as the second connecting material 42. In addition, since the configurations of both connecting materials 41 and 42 are the same, the first connecting material 41 will be mainly described below.

The first connection material 41 is formed in a rectangular shape and is sandwiched between the first bus bar 312 and the second adhesive layer 33. It is then fixed to the first bus bar 312 by a fixing material 5 such as solder. For example, it is preferable to use a low-melting point solder of 150°C or less as the fixing material 5 so that it can be fixed simultaneously in an autoclave when assembling the windshield described later. The first connection material 41 extends from the first bus bar 312 to the upper edge of the outer glass plate 1 and is exposed from the first notch 21 formed in the inner glass plate 2. In this exposed portion, a connection terminal to which a cable extending to a power source is connected is connected by a fixing material such as solder. In this way, the connection terminals of both connection materials 41, 42 are fixed to the portions exposed from the notches 21, 22 of the inner glass plate 2 without protruding from the ends of both glass plates 1, 2. In addition, because both connection members 41 and 42 are made of a thin material, as shown in FIG. 2, they can be folded and the ends fixed to the bus bar 312 with fixing material 5.

<1-4. Shielding layer>
As shown in FIG. 1, a shielding layer 7 is laminated on a dark color ceramic such as black on the periphery of the laminated glass. The shielding layer 7 blocks the view from inside and outside the vehicle, and is laminated along the four sides of the laminated glass. The bus bars 312 and 313 are disposed in positions covered by the shielding layer 7. In particular, the shielding layer 7 covers the entire outer edges and vicinity of the bus bars 312 and 313, and covers at least the step between the outer edges of the bus bars 312 and 313 and the base material 311 and the vicinity thereof. In addition, when the base material 311 is smaller than the adhesive layers 32 and 33, the shielding layer 7 covers at least the step between the base material 311 and the adhesive layers 32 and 33 and the vicinity thereof. The reference numeral 7 in the figure indicates the inner edge of the shielding layer 7.

The shielding layer 7 may be formed in various ways, such as only on the outer surface of the outer glass sheet 1, only on the inner surface of the outer glass sheet 1, or on the inner surfaces of the outer glass sheet 1 and the inner glass sheet 2. If the shielding layer 7 is provided on at least the outer glass sheet 1, it is possible to prevent bubbles from being seen from the outside of the vehicle. On the other hand, if a second shielding layer is provided on the inner glass sheet 2, it is possible to prevent bubbles from being seen from the inside of the vehicle. However, whether or not the second shielding layer prevents bubbles from being seen from the inside of the vehicle depends on the structure of the vehicle. In other words, if the bubbles are hidden by fitting the laminated glass into the vehicle body, it is considered that the second shielding layer is not necessary. However, in order to improve the quality of the laminated glass itself, or if the bubbles are not hidden by the vehicle body, it is preferable to provide a second shielding layer to hide the bubbles from the inside of the vehicle.

The ceramic may also be made of various materials, for example, the following composition:
*1, Main components: copper oxide, chromium oxide, iron oxide and manganese oxide *2, Main components: bismuth borosilicate, zinc borosilicate

The ceramic can be formed by screen printing, but it can also be produced by transferring a firing transfer film onto a glass plate and firing it. When using screen printing, for example, the following can be used: polyester screen: 355 mesh, coat thickness: 20 μm, tension: 20 Nm, squeegee hardness: 80 degrees, mounting angle: 75°, printing speed: 300 mm/s. The ceramic can be formed by drying in a drying oven at 150°C for 10 minutes.

The shielding layer 7 can also be formed by laminating ceramics or by attaching a dark-colored resin shielding film.

2. Windshield manufacturing method
Next, a method for manufacturing a windshield will be described. First, a manufacturing line for a glass sheet will be described.

Here, the forming mold will be described in more detail with reference to Figures 4 and 5. Figure 4 is a side view of the furnace through which the forming mold passes, and Figure 5 is a plan view of the forming mold. As shown in Figure 5, the forming mold 800 has a frame-shaped mold body 810 that roughly matches the outer shape of both glass plates 1 and 2. Since the mold body 810 is formed in a frame shape, it has an internal space 820 that penetrates in the vertical direction inside. The peripheral parts of both flat glass plates 1 and 2 are placed on the upper surface of the mold body 810. Therefore, heat is applied to the glass plates 1 and 2 from a heater (not shown) arranged on the lower side through the internal space 820. As a result, both glass plates 1 and 2 are softened by heating and curved downward due to their own weight. In addition, a shielding plate 840 for shielding heat may be arranged on the inner peripheral edge of the mold body 810, which can adjust the heat received by the glass plates 1 and 2. The heater can also be installed above the mold 800, not just below it.

After the above-mentioned shielding layer 7 is laminated on the flat outer glass plate 1 and inner glass plate 2, the outer glass plate 1 and inner glass plate 2 are stacked and passed through the heating furnace 802 as shown in FIG. 4 while being supported by the forming mold 800. When heated to near the softening point temperature in the heating furnace 802, the glass plates 1 and 2 are curved downward on the inside from the periphery due to their own weight, and are formed into a curved shape. Next, the glass plates 1 and 2 are carried from the heating furnace 802 to the annealing furnace 803, where they are annealed. After that, the glass plates 1 and 2 are carried out of the annealing furnace 803 and allowed to cool.

Thus, when the outer glass plate 1 and the inner glass plate 2 are formed, the intermediate layer 3 is sandwiched between the outer glass plate 1 and the inner glass plate 2. Specifically, first, the outer glass plate 1, the first adhesive layer 32, the heat generating layer 31, the second adhesive layer 33, and the inner glass plate 2 are laminated in this order. At this time, the surface of the heat generating layer 31 on which the first bus bar 312 and the like are formed faces the second adhesive layer 33. In addition, the upper and lower ends of the heat generating layer 31 are arranged inside the notches 21 and 22 of the inner glass plate 2. Furthermore, the notches of the first and second adhesive layers 32 and 33 are aligned with the notches 21 and 22 of the inner glass plate 2. As a result, the outer glass plate 1 is exposed from the notches 21 and 22 of the inner glass plate 2. Next, each connecting material 41 and 42 is inserted between the heat generating layer 31 and the second adhesive layer 33 from each notch 21 and 22. At this time, low-melting-point solder is applied to each connection material 41, 42 as a fixing material 5, and this solder is placed on each bus bar 312, 313.

The laminate consisting of the two glass plates 1, 2, the intermediate layer 3, and the connecting materials 41, 42 is then placed in a rubber bag and pre-bonded at approximately 70-110°C while applying reduced pressure. Other methods of pre-bonding are also possible, including the following method. For example, the laminate is heated in an oven at 45-65°C. Next, the laminate is pressed with a roll at 0.45-0.55 MPa. Next, the laminate is heated again in an oven at 80-105°C, and then pressed again with a roll at 0.45-0.55 MPa. In this way, the pre-bonding is completed.

Next, the main bonding is performed. The pre-bonded laminate is subjected to the main bonding in an autoclave, for example, at 8 to 15 atmospheres and 100 to 150°C. Specifically, the main bonding can be performed, for example, under conditions of 14 atmospheres and 135°C. Through the above pre-bonding and main bonding, both adhesive layers 32, 33 are bonded to the glass plates 1, 2 with the heat generating layer 31 sandwiched between them. In addition, the solder of the connecting members 41, 42 melts, and the connecting members 41, 42 are fixed to the bus bars 312, 313. In this way, the laminated glass according to this embodiment is manufactured. Note that curved windshields can also be manufactured by other methods, for example, by pressing.

<3. How to use the windshield>
The windshield configured as described above is attached to the vehicle body, and furthermore, connection terminals are fixed to each of the connection members 41, 42. When electricity is then passed through each of the connection terminals, a current is applied to the heating wire 314 via the connection members 41, 42 and each of the bus bars 312, 313, causing heat generation. This heat generation can defog the surface of the windshield on the inside of the vehicle or melt ice on the surface on the outside of the vehicle.

<4. Features>
As described above, according to this embodiment, the following effects can be obtained.

(1) As described above, the shielding layer 7 covers the entire outer edges of both bus bars 312, 313 and their vicinity, and at least covers the steps between the outer edges of both bus bars 312, 313 and the base material 311 and their vicinity. Therefore, bubbles that occur at the steps between the bus bars 312, 313 and the base material 311 can be hidden by the shielding layer 7. Therefore, even if bubbles are generated, they can be seen from outside the vehicle.

(2) Furthermore, the generation of bubbles can be suppressed by adjusting the thickness of the busbars 312, 313, the heating wire 314, and the base material 311. For example, an example of a windshield having an intermediate film 3 configured as follows will be described. In the following example, a heat generating layer 31 is disposed between both adhesive layers 32, 33 as shown below. The values in the table indicate thickness. Note that the busbars 312, 313 and the heating wire 314 are integrally formed and have the same thickness. Also, the appearance in the table below is a photograph of the vicinity of the busbar.

In Reference Examples 1 to 4, the heat generating layer 31 does not have a base material 311, but a step occurs between the busbars 312, 313 and the heating wire 314 and the adhesive layers 32, 33, so that air remains during manufacturing and bubbles occur. In Reference Examples 1 and 2, the bubbles are not noticeable, but in Reference Examples 3 and 4, the bubbles are noticeable and the range is wide. Therefore, in Reference Examples 3 and 4, although the busbars 312, 313 can be covered with the shielding layer 7, if the range of the bubbles is wide, the shielding layer 7 must also be widened. Therefore, it is preferable that the thickness of the busbars 312, 313 and the heating wire 314 is 30 μm or less. When the base material 311 is provided, a step occurs due to the thickness of the base material 311 in addition to the busbars 312, 313 and the heating wire 314, so the thickness of the heat generating layer (functional layer) 31 as a whole is preferably in the range of 5 to 200 μm, including the case where the thickness of the busbars 312, 313 is increased by an additional member. Furthermore, if the functional layer includes, for example, a film with a dimming function, the thickness is preferably in the range of 5 to 500 μm.

(3) The inventor discovered that when a voltage is applied to the heating wire 314 to heat the laminated glass, flickering occurs on objects outside the vehicle when the outside of the vehicle is viewed through the laminated glass. After investigating the cause of this, it was discovered that the heat from the heating wire 314 changes the refractive index of the resin layer in the vicinity, causing distortion. It was then discovered that the flickering occurs due to this change in refractive index.

Furthermore, the inventor found that the above-mentioned flickering occurs when the temperature of the heating wire 314 and its surroundings exceeds approximately 60°C. Therefore, the inventor found that flickering can be prevented by setting the heat generation amount per unit of the heating wire 314 to 2.0 W/m or less when a voltage of 13.5 V is applied between the bus bars 312 and 313 so that the temperature of the heating wire 314 and its surroundings does not exceed approximately 60°C. Therefore, in the windshield according to this embodiment, when a voltage of 13.5 V is applied between the bus bars 312 and 313, the heat generation amount per unit length of each heating wire 314 is set to 2.0 W/m or less, so that the temperature of the heating wire 314 and its surroundings can be kept to approximately 60°C or less, and as a result, flickering can be prevented when looking outside the vehicle through the windshield.

(4) Regarding the heating wire, for example, in the case of a windshield that requires a heat generation amount of 464 W/ ^m2 for an area of 1180 mm wide and 958 mm long at a voltage of 13.5 V, the heating wire can be set as shown in FIG. 10.

The shape of the heating wire 314 to satisfy the above heat generation amount is as shown in Reference Examples 5 to 16 in FIG. 10. However, the pitch of the heating wire 314 is required to be 1.25 mm or more according to the above-mentioned regulations, so it is preferable to adopt the heating wires of Reference Examples 15 and 16. Therefore, taking this pitch into consideration, it is preferable that the line width of the heating wire 314 is 10 μm or more.

When the voltage is 48 V under the same conditions as in FIG. 10, the heating wires can be set as shown in FIG. 11. In this case, in order to prevent flickering, it is preferable that the heat generation per unit length of each heating wire is 2.0 W/m or less. Also, the pitch is preferably 4.0 mm or less. Under such conditions, it is preferable to adopt the heating wires of Reference Examples 17 to 19 and 21. In that case, it is preferable that the line width of the heating wire is approximately 10 μm or less, and more preferably 8 μm or less.

(5) Both bus bars 312, 313 and the heating wire 314 are made of the same material, so that the linear expansion coefficients of both bus bars 312, 313 and the heating wire 314 are the same. This has the following advantages. If both bus bars 312, 313 and the heating wire 314 are made of different materials, the linear expansion coefficients will be different. For example, if these components are made separately and fixed, there is a possibility that problems will occur, such as the heating wire peeling off from the bus bars due to severe environmental changes such as heat cycle testing, and the two glass sheets that make up the laminated glass will lift up from each other. However, if both bus bars 312, 313 and the heating wire 314 are made of the same material as in this embodiment, such problems can be prevented.

(6) Both bus bars 312, 313 and the heating wire 314 are integrally formed, so that poor contact between them and therefore poor heat generation can be prevented. The detailed explanation of poor heat generation is as follows. Generally, when a glass plate is heated for anti-fogging purposes, it is required to control the current value so that the upper limit of the heating temperature is, for example, 70 to 80°C in order to prevent the occurrence of glass cracks. In contrast, if there is localized heat generation due to the contact resistance as described above, it is necessary to control the current value by setting that part as the upper limit of the heating temperature. As a result, there is a problem that the heating wire cannot be controlled so that it generates sufficient heat overall. However, with the above configuration, localized heat generation can be prevented, and the heating wire can also be controlled so that it generates sufficient heat overall.

(7) In the above embodiment, two connecting members 41, 42 are used to connect each bus bar 312, 313 to an external terminal. However, it is also possible to use a wider bus bar, for example, by preparing a wider bus bar, cutting off unnecessary portions of the bus bar, and exposing portions of the bus bar from the cutouts 21, 22, as a substitute for the connecting members. However, doing so may cause localized heat generation at the corners of the cut bus bar. In contrast, in the present embodiment, separate connecting members 41, 42 are fixed to each bus bar 312, 313, so that such localized heat generation can be prevented.

5. Modifications
Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and various modifications are possible without departing from the spirit of the present invention. In addition, the following modified examples can be appropriately combined.

<5.1>
The heating layer 31 can be formed in various shapes. For example, a sheet-like heating layer 31 having both bus bars 312, 313 and a heating wire 314 formed on a substrate 311 can be prepared in advance, cut appropriately, and then arranged between the two glass plates 1 and 2. Therefore, for example, if the edges of the glass plates 1 and 2 are curved, the edges of the substrate 311 can be curved accordingly. In addition, the heating layer 31 does not need to completely match the shape of the glass plates 1 and 2, and can be arranged only in the area where the anti-fogging effect is desired, so that it can be formed in various shapes, such as a shape smaller than the glass plates 1 and 2. The glass plates 1 and 2 can also be formed in various shapes other than a perfect rectangle.

In the above embodiment, both bus bars 312, 313 and the heating wire 314 are arranged on the base material 311, but it is sufficient that at least the heating wire 314 is arranged. Therefore, for example, both bus bars 312, 313 can also be arranged between both adhesive layers 32, 33.

In addition, the intermediate film 3 may be configured such that, for example, the adhesive layers 32, 33 are not provided, and a base material 311 supporting the bus bars 312, 313 and the heating wire 314 is disposed between the two glass plates 1, 2. In this case, the base material 311 serves as an adhesive layer.

<5.2>
The configuration of the heating wire 314 is not particularly limited, and various configurations are possible. This will be described with reference to Fig. 8. The example in Fig. 12 differs from the above embodiment mainly in the arrangement of the busbars and the heating wires, so only the different parts will be described below, and the same components will be denoted by the same reference numerals and description thereof will be omitted.

As shown in FIG. 12, in this example, the multiple heating wires 6 are arranged in parallel to connect both bus bars 312, 313. Each heating wire 6 is composed of three parts and two folded parts. That is, the first part 61 extends from the first bus bar 312 to a position close to the second bus bar 313, the second part 62 extends upward from the lower end of the first part 61 via the first folded part 64 to a position close to the first bus bar 312, and the third part 63 extends downward from the upper end of the second part 62 via the second folded part 65 and is connected to the second bus bar 313. The multiple heating wires 6 thus formed are arranged at a predetermined interval in the left-right direction of both bus bars 312, 313.

In the above example, each heating wire 6 can be lengthened by providing folded sections 64, 65 to each heating wire. This makes it possible to reduce the amount of heat generated by each heating wire 6.

The shape of the heating wire 6 is not particularly limited. In this embodiment, the heating wire 6 is formed to have two folded portions 64, 65, but it is also possible to provide three or more folded portions and further increase the length of the heating wire 6 extending between the two bus bars 212, 213.

<5.3>
In order to lengthen each heating wire 314, a relay bus bar as shown in Fig. 13 may be provided. This point will be described in detail.

9, in this windshield, the first bus bar 312 is disposed on the left side of the bottom edge 12 of each glass plate 1, 2, and the second bus bar 313 is disposed along the right side of the bottom edge 12. In addition, a strip-shaped first relay bus bar 71 is provided on the left side of the top edge 11 of the glass plates 1, 2, a strip-shaped second relay bus bar 72 is provided between the first and second bus bars 312, 313 on the bottom edge 12, and a strip-shaped third relay bus bar 73 is provided on the right side of the top edge 11 of the glass plates 1, 2. The first relay bus bar 71 is disposed in a position opposite the first bus bar 312 and the second relay bus bar 72, and is formed to have approximately the same length from the left end of the first bus bar 312 to near the center of the second relay bus bar 72. The third relay busbar 73 is disposed in a position opposite the second relay busbar 72 and the second busbar 313, and is formed to have approximately the same length from the left end of the first busbar 312 to near the center of the second relay busbar 72.

The heating wires 6 are each composed of four parts. That is, the heating wires 6 are each composed of a first part 601 connecting the first bus bar 312 and the first relay bus bar 71, a second part 602 connecting the first relay bus bar 71 and the second relay bus bar 72, a third part 603 connecting the second relay bus bar 72 and the third relay bus bar 73, and a fourth part 604 connecting the third relay bus bar 73 and the second bus bar 313. The first parts 601 extend upward from the first bus bar 312 in approximately parallel relation and are connected to the left half of the first relay bus bar 71. The second parts 602 extend downward from the right half of the first relay bus bar 71 in approximately parallel relation and are connected to the left half of the second relay bus bar 72. The third portions 603 extend generally parallel to each other from the left half of the second relay bus bar 72 toward the top and are connected to the third relay bus bar 73. The fourth portions 604 extend generally parallel to each other from the right half of the third relay bus bar 73 toward the bottom and are connected to the second bus bar 213.

In the above example, three relay bus bars 71 to 73 are provided between the first bus bar 312 and the second bus bar 313, and multiple heating wires 6 arranged in parallel through these are configured to connect the first bus bar 312 and the second bus bar 313. Therefore, the length of the heating wire 6 between the first bus bar 312 and the second bus bar 313 can be increased. This makes it possible to reduce the amount of heat generated in each heating wire 6.

In this example, both bus bars 312, 313 are arranged along the lower side 12, but they can also be arranged along the upper side 11. That is, as shown in FIG. 9, both bus bars 312, 313 and the three relay bus bars 71 to 73 can be arranged in upside-down positions. The number of relay bus bars is not particularly limited, and two or four or more can be provided, as long as both ends of the heating wire pass through all the relay bus bars and are connected to the first bus bar 312 and the second bus bar 313.

<5.4>
Also, adjacent heating wires 314 can be connected to each other by at least one bridge. This allows current to flow through the adjacent heating wire 314, for example, even if one heating wire 314 is broken. The position and number of bridges are not particularly limited. The shape of the bridge is also not particularly limited, and various shapes can be used, such as an obliquely extending bridge or a corrugated bridge. The bridge can be made of the same metal material as the heating wire 314 and formed integrally with the heating wire 314.

<5.5>
There are no particular limitations on the shape of the connecting members 41, 42 or the configuration of the cutouts 21, 22 of the inner glass plate 2. For example, a small cutout portion approximately the same thickness as the connecting members 41, 42 may be formed in the inner glass plate 2, and the connecting members 41, 42 extending from the respective bus bars 312, 313 may be folded back at this cutout portion and attached to the surface of the inner glass plate 2. In this way, it is possible to prevent the connecting members 41, 42 from protruding in the planar direction from the end of the laminated glass.

<5.6>
The shape of the glass plates 1 and 2 is not particularly limited, and does not necessarily have to be rectangular as long as the upper side 11, the lower side 12, the left side 13, and the right side 14 can be clearly identified. Furthermore, each of the sides 11 to 14 may be a straight line or a curved line.

<5.7>
In the above embodiment, the bus bars 312, 313 are arranged along the upper and lower edges of the glass plate, respectively. However, the bus bars may also be arranged along the left and right edges of the glass plate so that the heating wires extend in the left-right direction.

<5.8>
In the above embodiment, the heat generating layer 31 is provided as the functional layer according to the present invention, but a functional layer having other functions may also be provided. For example, an infrared reflective film, a light control film, a crime prevention sheet, a color film, a film for a head-up display, etc. may be provided. Even when such a functional layer is provided, if a step is formed between the adhesive layers 32 and 33, there is a risk of bubbles being generated as described above, so it is necessary to cover the step with the shielding layer 7.

In particular, when an infrared reflective film is used as the functional layer 31, the edges of the film may react with the plasticizer and discolor. Therefore, even when such a functional layer 31 is provided, discoloration can be prevented by the shielding layer 7.

Films such as infrared reflective films, light control films, security sheets, and color films can cause wrinkles, especially at the edges of laminated glass, depending on the stretching of the film. Even in such cases, the wrinkles can be blocked by the shielding layer 7.

<5.9>
The shape of the shielding layer 7 is not particularly limited, and it may be formed along the peripheral edge of the laminated glass as in the above embodiment, or it may be positioned so as to cover at least the step between the heating layer 31 and the adhesive layers 32, 33.

<5.10>
In the above embodiment, the laminated glass of the present invention is applied to a windshield of an automobile, but it can also be applied to a side window or a rear window. In addition, it is not limited to an automobile, but can also be applied to other vehicles such as a train, window glass of a building, etc.

1 Outer glass plate 2 Inner glass plate 3 Intermediate layer 31 Heat generating layer (functional layer)
311: Base material 312: First bus bar 313: Second bus bar 314: Heating wire

Claims (10)

an outer glass sheet having a first side and a second side opposite the first side;
An inner glass plate arranged opposite the outer glass plate and having substantially the same shape as the outer glass plate;
an interlayer disposed between the outer glass sheet and the inner glass sheet;
a shielding layer formed on a surface of the outer glass sheet;
Equipped with
The intermediate film is
An adhesive layer;
A functional layer supported by the adhesive layer,
a first bus bar at least a portion of which extends along the end of the first side;
a second bus bar at least a portion of which extends along the end of the second side;
a plurality of heating wires arranged to connect the first bus bar and the second bus bar;
Equipped with
the plurality of heating wires are connected in parallel to the first bus bar and the second bus bar as electrodes;
The voltage applied to both bus bars is less than 20 V;
The width of the surface of the heating wire on the adhesive layer side is equal to or greater than the thickness of the heating wire,
The cross-sectional shape of the heating wire is trapezoidal.
A functional layer;
Equipped with
At least a part of an outer periphery of the functional layer has an inner portion located inside an outer periphery of the outer glass plate,
The functional layer is
a part of an outer circumferential edge of the first bus bar and a part of an outer circumferential edge of the second bus bar constitutes the inner portion,
the shielding layer is formed so as to cover both bus bars and the vicinities of their peripheral edges,
The width of the heating line is 7 to 30 μm,
The thickness of the heating wire is 5 to 30 μm.
Laminated glass. an outer glass sheet having a first side and a second side opposite the first side;
An inner glass plate arranged opposite the outer glass plate and having substantially the same shape as the outer glass plate;
an interlayer disposed between the outer glass sheet and the inner glass sheet;
a shielding layer formed on a surface of the outer glass sheet;
Equipped with
The intermediate film is
An adhesive layer;
A functional layer supported by the adhesive layer,
a first bus bar at least a portion of which extends along the end of the first side;
a second bus bar at least a portion of which extends along the end of the second side;
a plurality of heating wires arranged to connect the first bus bar and the second bus bar;
Equipped with
the plurality of heating wires are connected in parallel to the first bus bar and the second bus bar as electrodes;
The voltage applied to both bus bars is 20 to 50 V,
The width of the surface of the heating wire on the adhesive layer side is equal to or greater than the thickness of the heating wire,
The cross-sectional shape of the heating wire is trapezoidal.
A functional layer;
Equipped with
At least a part of an outer periphery of the functional layer has an inner portion located inside an outer periphery of the outer glass plate,
The functional layer is
a part of an outer circumferential edge of the first bus bar and a part of an outer circumferential edge of the second bus bar constitute the inner portion,
the shielding layer is formed so as to cover both bus bars and the vicinities of their peripheral edges,
The width of the heating line is 1 to 10 μm,
The thickness of the heating wire is 5 to 30 μm.
Laminated glass. The laminated glass according to claim 1 or 2, wherein the shielding layer is located on the surface of the outer glass sheet facing the interlayer film. The laminated glass according to any one of claims 1 to 3, further comprising a second shielding layer provided on the surface of the inner glass sheet opposite the interlayer film. The laminated glass according to any one of claims 1 to 4, wherein the shielding layer is formed around the entire outer peripheral edge of the outer glass sheet. The laminated glass according to any one of claims 1 to 5, wherein the shielding layer is disposed between the outer glass sheet and the interlayer film. The laminated glass according to claims 1 to 6, wherein the thickness of the functional layer is 5 to 200 μm. The functional layer further includes a support layer that supports the bus bars and the heating wire,
8. The laminated glass of claim 1, wherein the support layer is in contact with the adhesive layer. The laminated glass according to any one of claims 1 to 8, wherein the bus bars are formed by laminating multiple metal layers. 10. The laminated glass according to claim 1, wherein the heating wire has a heat value of 2.0 W/m or less.