Manufacturing method for laminated glass for automobile windows

Abstract

This manufacturing method for laminated glass for an automobile window includes: a bending formation step in which two glass plates are heated and subjected to bending formation; and a lamination step in which the two glass plates which were subjected to bending formation are laminated with an intermediate film interposed therebetween. Following the bending formation step, a recessed surface of at least one glass plate of the two glass plates is cleaved.

Description

[Technical field]

[0001] The present invention relates to a method for producing laminated glass for automobile windows. [Background technology]

[0002] Automobiles are required to have safety performance not only from the viewpoint of protecting passengers but also from the viewpoint of protecting the body of a pedestrian in the event of a collision with the pedestrian. In response to such a requirement, for example, Patent Document 1 proposes a configuration in which, when a pedestrian collides head-on with an automobile and a downward impact is applied from the front to the periphery of the cowl louvers and the windshield glass, the connected cowl louvers and the windshield are separated, thereby ensuring the body protection performance of the pedestrian. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2017-213928 A Summary of the Invention [Problem to be solved by the invention]

[0004] According to recent accident investigations, it has been reported that when a cyclist or motorcycle rider crashes head-on into a car, the cyclist's body is more likely to collide with the car at a higher position than a pedestrian, i.e., the cyclist's body is more likely to collide with the windshield. Furthermore, due to the structure of recent automobiles with short front noses, pedestrians are also more likely to collide with the windshield. Therefore, window glass such as windshields is also required to improve the body protection performance for pedestrians and cyclists (hereinafter also referred to as pedestrians, etc.). Here, in order to improve the body protection performance of laminated glass for automobile windows such as windshields against pedestrians, etc., it is important that the glass sheets themselves absorb the impact by appropriately breaking during a collision, and that the interlayer film between the glass sheets also exhibits the functions of impact absorption and penetration prevention, thereby reducing the impact and damage to the bodies of pedestrians, etc.

[0005] However, it is known that glass sheets inherently have a strength distribution within their plane, and the strength of glass sheets is usually determined probabilistically based on the safety factor, breakage probability, etc. Therefore, even if the strength of the window glass as a whole is appropriate, there may be localized areas within the plane of the window glass where the strength is excessively high (hereinafter also referred to as high-strength areas), and when a pedestrian or the like collides into such a high-strength area, the window glass is not likely to break, so the window glass is unable to absorb the impact and the interlayer film is unable to perform its function, which may increase the possibility of injury to the human body.

[0006] In order to reduce the strength in the high strength region as described above, it is possible to reduce the strength of the automobile window glass as a whole by changing the composition or manufacturing method of the glass. However, in that case, the strength is also reduced in the region where the strength in the plane is relatively low, so there is a possibility that the robustness required for the automobile window glass cannot be secured. Therefore, there is a demand for automobile window glass with high safety performance in the event of a collision from the viewpoint of protecting the body of pedestrians, etc. as described above, by reducing or eliminating the region where the strength is excessively high and making the strength distribution in the plane as uniform as possible.

[0007] An object of one aspect of the present invention is to obtain a laminated glass for automobile windows that has the robustness required for automobile window glass and also has high performance for protecting pedestrians and other bodies in the event of a collision. [Means for solving the problem]

[0008] One aspect of the present invention is a method for producing laminated glass for automobile windows, comprising a bending step of heating and bending two glass sheets, and a lamination step of laminating the two bent glass sheets together via an interlayer film, wherein after the bending step, a concave surface of at least one of the two glass sheets is scratched. Effect of the Invention

[0009] According to one aspect of the present invention, it is possible to provide a laminated glass for automobile windows that has the robustness required for automobile window glass and also has high physical protection performance for pedestrians and the like in the event of a collision. [Brief description of the drawings]

[0010] [Figure 1] 1 is a front view of an automobile equipped with a laminated glass according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a cross-sectional view of the laminated glass shown in FIG. [Diagram 3] FIG. 1 is a flow diagram of an example of a method for producing laminated glass according to a first embodiment of the present invention. [Figure 4] FIG. 4 is a diagram for explaining scratching in the first embodiment. [Diagram 5] 1 is a cross-sectional view of a curved glass sheet cut in the conveying direction with a rotating brush in contact with the glass sheet; [Figure 6] FIG. 4 is a flow diagram of an example of a method for producing laminated glass according to a second embodiment of the present invention. [Figure 7] FIG. 11 is a diagram for explaining an example of damage in the second embodiment. [Figure 8] FIG. 4 is a flow diagram of an example of a method for producing laminated glass according to a third embodiment of the present invention. [Figure 9] FIG. 13 is a diagram for explaining an example of damage in the third embodiment. [Figure 10] FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] <Basic structure of laminated glass> The laminated glass 1 for automobile windows manufactured according to one embodiment of the present invention is used as a window glass for an automobile. Fig. 1 shows an automobile 100 equipped with the laminated glass 1 for automobile windows. In this example, the laminated glass 1 for automobile windows is glass installed in an opening (window) at the front of the vehicle body, that is, a windshield, but the laminated glass 1 for automobile windows according to this embodiment can also be used as window glass other than a windshield, for example, a side glass, a rear glass, or a roof glass.

[0012] Fig. 2 shows a partial cross-sectional view of the laminated glass for automobile windows 1 shown in Fig. 1. As shown in Fig. 2, the laminated glass for automobile windows 1 may be formed by bonding an exterior glass sheet 10 and an interior glass sheet 20 together via an interlayer film 30. As shown in Fig. 2, the exterior glass sheet 10 has a first surface 11 that is the surface facing the exterior of the vehicle and a second surface 12 that is the surface facing the interior of the vehicle, and the interior glass sheet 20 has a third surface 21 that is the surface facing the exterior of the vehicle and a fourth surface 22 that is the surface facing the interior of the vehicle.

[0013] The material constituting the exterior glass plate 10 and the interior glass plate 20 (hereinafter, collectively referred to as glass plates) in the laminated glass 1 is preferably inorganic glass. Examples of inorganic glass include soda lime silicate glass, aluminosilicate glass, borate glass, lithium aluminosilicate glass, and borosilicate glass. The method for forming the glass plate made of inorganic glass is not particularly limited, but the glass plate is preferably formed by, for example, a float method. The glass plate may be unreinforced glass (raw glass). Unreinforced glass is glass obtained by forming molten glass into a plate shape and slowly cooling it, and is not subjected to a strengthening treatment such as air-cooling strengthening treatment or chemical strengthening treatment. By using unreinforced glass, even if the glass is broken by impact, the entire surface does not shatter into small pieces, and the visibility of the occupants can be secured even in the event of an accident.

[0014] The thicknesses of the exterior glass sheet 10 and the interior glass sheet 20 may be the same or different from each other. The thickness of the exterior glass sheet 10 may be 1.1 mm or more and 3.5 mm or less. The thickness of the interior glass sheet 20 may be 0.5 mm or more and 2.3 mm or less. Furthermore, the overall thickness of the laminated glass for automobile windows 1 may be 2.3 mm or more and 8.0 mm or less. The configurations of the exterior glass sheet 10 and the interior glass sheet 20 (materials constituting the glass sheets, manufacturing method of the glass sheets, etc.) may be the same or different from each other.

[0015] The material of the intermediate film 30, which is disposed between the vehicle exterior glass plate 10 and the vehicle interior glass plate 20 and bonds the vehicle exterior glass plate 10 and the vehicle interior glass plate 20, is not particularly limited, but is preferably a thermoplastic resin. Examples of the material of the intermediate film 30 include thermoplastic resins that have been used for various applications, such as plasticized polyvinyl acetal resins, plasticized polyvinyl chloride resins, saturated polyester resins, plasticized saturated polyester resins, polyurethane resins, plasticized polyurethane resins, ethylene-vinyl acetate copolymer resins, ethylene-ethyl acrylate copolymer resins, cycloolefin polymer resins, and ionomer resins. In addition, a resin composition containing a modified block copolymer hydrogenated product described in Japanese Patent No. 6065221 can also be preferably used. Among these, plasticized polyvinyl acetal resins are preferably used because they have an excellent balance of various performances such as transparency, weather resistance, strength, adhesive strength, penetration resistance, impact energy absorption, moisture resistance, heat insulation, and sound insulation. The above thermoplastic resins may be used alone or in combination of two or more. The term "plasticized" in the plasticized polyvinyl acetal resin means that the resin is plasticized by adding a plasticizer. The same applies to other plasticized resins.

[0016] The intermediate film 30 may be a resin that does not contain a plasticizer, such as an ethylene-vinyl acetate copolymer resin. Examples of the polyvinyl acetal resin include polyvinyl formal resin obtained by reacting polyvinyl alcohol (PVA) with formaldehyde, polyvinyl acetal resin in the narrow sense obtained by reacting PVA with acetaldehyde, and polyvinyl butyral resin (PVB) obtained by reacting PVA with n-butylaldehyde. In particular, PVB is a suitable material because it has an excellent balance of various properties such as transparency, weather resistance, strength, adhesive strength, penetration resistance, impact energy absorption, moisture resistance, heat insulation, and sound insulation. The above resins may be used alone or in combination of two or more kinds.

[0017] A shielding layer may be provided on the periphery of the laminated glass for automobile windows 1 to protect a sealant or the like that adheres and holds the laminated glass for automobile windows 1 to the vehicle body. The shielding layer may be formed, for example, by applying a ceramic color paste of a low brightness color such as black, gray, or brown, which contains a fusible glass frit containing a black pigment, and then firing the paste. The shielding layer may be formed on the periphery of one or more of the second surface 12, the third surface 21, and the fourth surface 22 (FIG. 2) of the laminated glass for automobile windows 1, preferably on the periphery of at least one of the second surface 12 and the fourth surface 22. The shielding layer may be provided over a range of 10 mm to 300 mm from the peripheral edge of the glass sheet.

[0018] 2, the laminated glass for automobile windows 1 may be curved as a whole or in part so as to be convex toward the exterior side of the vehicle. In this case, the exterior side glass sheet 10 and the interior side glass sheet 20 can be curved to a desired predetermined curvature in one direction or two directions by a bending forming process described later.

[0019] <Method of manufacturing laminated glass for automobile windows> The manufacturing method of the laminated glass for automobile windows according to the embodiment of the present invention may be roughly divided into a flat glass sheet preparation step of preparing two flat glass sheets cut into a desired shape, a bending step of heating and bending the two flat glass sheets, a cleaning step of cleaning the two bent glass sheets, and a bonding step of bonding the two bent glass sheets together via an intermediate film. In this embodiment, after the bending step, the concave surface of at least one of the two glass sheets is scratched. In this specification, "cracking" refers to a process of forming fine cracks (also called microcracks, fine cracks on the order of micrometers or less that cannot be visually recognized) on the surface of the glass sheet.

[0020] Conventionally, various safety-related properties and functions have been required for laminated glass for automobile windows, but the requirements are becoming greater. In particular, in recent years, importance has been attached not only to the viewpoint of passenger protection but also to the viewpoint of protecting the body of pedestrians (pedestrians, cyclists, etc.) when they collide. Laminated glass for automobile windows is also required to satisfy specific standards such as the Head Injury Criterion (HIC), on the premise that it has appropriate robustness as automobile window glass. For example, a HIC value of less than 1,000, preferably less than 650, may be required in a specific region of laminated glass for automobile windows. Here, in order to improve the body protection performance of pedestrians, etc. in the event of a collision, it is important that the region (high strength region) in laminated glass for automobile windows with excessively high strength is reduced or eliminated, and the distribution of strength over the surface direction is suppressed (the strength distribution is narrowed), that is, the strength within the surface is made as uniform or level as possible.

[0021] In the manufacturing method of laminated glass according to the present embodiment, the strength of the glass plate and the laminated glass obtained by using the glass plate can be made uniform or leveled in the surface direction by scratching the surface of the glass plate after manufacturing. Although fine cracks are originally present on the surface of the glass plate after manufacturing, and the uneven distribution of these fine cracks is said to be the cause of the variation in the strength of automotive window glass, according to the manufacturing method of the present embodiment, it is considered that the strength of the region where the strength is excessively high (high strength region) can be reduced by introducing new fine cracks into the surface of the glass plate by scratching. On the other hand, the scratching in the present embodiment is a treatment that does not further reduce the strength of the region where the strength is relatively low, or hardly reduces it at all. Therefore, in the present embodiment, by performing scratching, the in-plane strength of the glass plate or the obtained laminated glass can be made uniform, and the strength required for automotive window glass is also maintained. As a result, it is possible to provide a laminated glass for automotive windows that has the necessary robustness as automotive window glass and also has the performance of ensuring the physical safety of pedestrians and the like even when they collide with it.

[0022] In the manufacturing method according to this embodiment, the scratching is performed after the bending process as described above. The bending process involves a temperature rise near the softening point of the glass sheet or above the softening point, so if the scratching is performed before the bending process, the shape of the fine cracks formed on the surface of the glass sheet may be deformed by heat, reducing the effect of the introduced cracks. In contrast, according to the manufacturing method of this embodiment in which the scratching is performed after the bending process, the shape of the introduced cracks is not deformed by heat, so the effect of the cracks at the time of introduction can be well maintained.

[0023] Furthermore, the above-mentioned damage is applied to at least one of the two bent glass sheets, the surface that faces the inside of the vehicle when the glass sheet is attached to the vehicle. When a pedestrian or the like collides with the windshield of the vehicle from the outside of the vehicle, the impact of the collision is transmitted in sequence from the first surface 11 of the exterior glass sheet 10, which is the outermost surface, to the fourth surface 22 (FIG. 2) of the interior glass sheet 20, which is the innermost surface. At this time, in the exterior glass sheet 10, a compressive stress against a compressive force that contracts the area occurs on the first surface 11, and conversely, a tensile stress against a tensile force that expands the area occurs on the second surface 12, so that the exterior glass sheet 10 is likely to start cracking from the second surface 12 on the inside of the vehicle. For this reason, it is preferable that the second surface 12 is appropriately susceptible to cracking in the event of a collision, that is, there is no or little high-strength region in which the strength is excessively high locally on the second surface 12. Similarly, when focusing on the interior glass sheet 20, a compressive stress against a compressive force that contracts the area occurs in the third surface 21, and a tensile stress against a tensile force that expands the area occurs in the fourth surface 22, so that the interior glass sheet 20 is likely to start cracking from the fourth surface 22 on the interior side of the vehicle. Therefore, it is preferable that the fourth surface 22 is appropriately susceptible to cracking during a collision, that is, there is no or little high-strength area in which the strength is excessively high locally in the fourth surface 22. Therefore, in this embodiment, from the viewpoint of protecting the bodies of pedestrians and the like during a collision, at least one of the second surface 12 on the interior side of the exterior glass sheet 10 and the fourth surface 22 on the interior side of the interior glass sheet 20 is scratched. Furthermore, if it is only one of the second surface 12 and the fourth surface 22, it is more preferable to scratch the second surface 12, which is more affected by the impact during a collision, and it is even more preferable to scratch both the second surface 12 and the fourth surface 22.

[0024] The second surface 12 and the fourth surface 22, which face the interior side when the laminated glass is attached to the body of an automobile, are concave, particularly in the case of a windshield, as shown in Fig. 2. Therefore, in this embodiment, by scratching the concave surface of at least one of the two bent glass sheets, it is possible to obtain a laminated glass in which at least one of the second surface 12 and the fourth surface 22 has been scratched.

[0025] (Manufacturing method according to the first embodiment) Fig. 3 is a flow diagram showing an example of the method for producing laminated glass for automobile windows according to embodiment 1. As shown in Fig. 3, this production method roughly comprises a flat glass sheet preparation step (S10), a bending forming step (S20), a cleaning step (S30), and a bonding step (S40).

[0026] The flat glass sheet preparation step (S10) may include, for example, manufacturing a long belt-shaped glass sheet by a float method, a roll-out method, or the like, slowly cooling the belt-shaped glass sheet, cutting out a blank sheet from the belt-shaped glass sheet, cutting the blank sheet into a desired shape, for example, the shape of a windshield, chamfering, and printing a shielding layer. The order of these steps may be partially changed, and some of the steps may be omitted or additional steps may be included.

[0027] The flat glass sheet obtained in the flat glass sheet preparation step (S10) is subjected to the bending step (S20). The bending step (S20) is a step of bending the flat glass sheet by heating it to near its softening point or above its softening point. The heating temperature of the glass during bending (S22) may be specifically 550°C or more and 700°C or less. The bending method is not particularly limited, and may be gravity bending in which the flat glass sheet is placed on a ring mold and the glass sheet is bent by its own weight in a heating furnace, or press bending in which the glass sheet is sandwiched and pressed between a ring mold (lower mold) and a press mold (upper mold), or a combination thereof. In the first embodiment, the bending step (S20) includes stacking two flat glass sheets that will later become laminated glass (S21) and bending (S22), but each of the two flat glass sheets that will later become laminated glass may be bent one by one. In that case, the step (S21) of overlapping the two flat glass plates is unnecessary.

[0028] The bending (S22) may be a single-bend bending in which a flat glass sheet is bent in only one direction, for example, only in the left-right or up-down direction of the automobile when the glass sheet is attached to an opening of the automobile, or a compound-bend bending in both the left-right and up-down directions. The radius of curvature of the glass sheet obtained by bending (S22) may be 200 mm or more and 30,000 mm or less. The radii of curvature of the exterior glass sheet 10 and the interior glass sheet 20 in the laminated glass for automobile windows 1 may be the same or different.

[0029] After bending (S22), the bent glass sheet can be subjected to a cleaning step (S30). In the first embodiment, scratching (Sc) is performed in the cleaning step (S30). More specifically, the cleaning step (S30) includes separating (S31) the two glass sheets that were stacked in the bending step (S20), scratching (Sc), cleaning with a cleaning solution (S32), and drying (S33). It is preferable to cool the glass sheets before separating (S31) the two glass sheets.

[0030] In this embodiment, the scratching (Sc) can be performed, for example, by using a scratching tool (scratching means) to bring the scratching tool into contact with the surface of the glass plate and move it relative to the surface of the glass plate. In this embodiment, the scratching can be performed before cleaning with a cleaning liquid (S32) or as a cleaning step. Performing the scratching before cleaning with a cleaning liquid (S32) is preferable in that invisible glass powder that may be generated by the scratching can be removed by cleaning (S32).

[0031] The form of the scratching tool used is not particularly limited, but it is preferable that the scratching element is provided on the peripheral surface of the shaft, and the scratching element is brought into contact with the surface of the glass plate by moving or rotating the shaft relative to the glass plate, and can be moved relative to the surface of the glass plate. The scratching element may be a fiber or a fiber bundle, or a film or a sheet. The scratching tool may be, for example, a scratching tool (rotating brush, etc.) in which fibers are implanted on the peripheral surface of a rotatable shaft so as to extend radially when viewed in cross section. Alternatively, it may be a scratching tool (rotating flap) in which one or more sheet-like flaps are attached to the peripheral surface of a rotatable shaft. In addition, the sheet-like flap may be attached to a support that does not rotate, and the end of the sheet-like flap may be rubbed against the glass plate (non-rotating flap). The above-mentioned fiber or sheet, which is the scratching element, is preferably flexible. Furthermore, as another example, the scratching tool may be a form in which a film, sheet, disk, etc. is placed so that its surface faces the surface of the glass plate, and moved in the surface direction to rub the surface of the glass plate.

[0032] FIG. 4 shows a schematic diagram of the scratching by the scratching means 160 including one or more rotating brushes 161 as a scratching tool. FIG. 4 shows the scratching (Sc) before cleaning (S32) using a cleaning liquid, as viewed from above the equipment (vertically from above). As shown in FIG. 4, the bent glass sheets (bent glass sheets) G, G, ... are transported one by one in the transport direction Dt. In the example shown in FIG. 4, the transport means 150 is a conveyor having two conveyor belts that extend along the transport direction Dt of the glass sheet G and move along the transport direction Dt, but the transport means is not limited to the one shown in the figure. In the example shown in FIG. 4, the axial direction of the rotating brush 161 is arranged along the orthogonal direction Dv that is perpendicular to the transport direction Dt, but the orientation of the rotating brush 161 is not limited to the example shown in the figure. For example, the rotating brush 161 may be arranged so that the axial direction is along the transport direction Dt or oblique to the transport direction Dt.

[0033] 5 is a cross-sectional view (cross-sectional view of line II in FIG. 4) of the glass sheet G in contact with the rotating brush 161, cut along the conveying direction Dt. As shown in FIG. 5, the rotating brush 161 has brush fibers 161a radially planted from the circumferential surface of a shaft body 161b. The material of the fibers of the rotating brush 161 may be natural fibers (animal hair) or synthetic fibers (resin, etc.). When the brush fibers are made of resin or contain resin, specific examples of the resin include ultra-low density polyethylene, linear low density polyethylene, low density polyethylene, high density polyethylene, polypropylene, polystyrene, polyurethane, silicone resin, ethylene vinyl acetate (EVA), and olefin-based elastomers.

[0034] The rotating brush 161 is configured and arranged so that at least the tips of the embedded brush fibers 161a come into contact with the concave surface F2 of the curved glass sheet G to be scratched. The concave surface F2 of the glass sheet G is the surface that will become the second surface 12 of the exterior glass sheet 10 or the fourth surface 22 (FIG. 2) of the interior glass sheet 20 in the resulting laminated glass. The rotating brush 161 may have the same diameter overall along the axial direction of the rotating brush 161, or the diameter may vary depending on the position in the axial direction along the curvature of the curved glass sheet G. Furthermore, the axis itself may be curved along the curvature of the curved glass sheet G.

[0035] In the example shown in Fig. 4 and Fig. 5, the glass sheets G, G, ... are placed on the conveying means 150 so that the convex surface faces upward and the concave surface F2 faces downward, and therefore the rotating brush 161 is also arranged below the glass sheets G, G, ..., but the up-down orientation of the glass sheet G and the position of the rotating brush 161 are not limited as long as the concave surface F2 of the glass sheet is damaged by the scratching means 160. Therefore, the bent glass sheets G, G, ... conveyed after the bending process (S20) are arranged so that the convex surface faces downward and the concave surface faces upward, and the rotating brush 161 may be arranged above the bent glass sheet G. However, when scratching (Sc) is performed according to the example of Fig. 4 and Fig. 5, the up-down orientation of the glass sheets G, G, ... conveyed in a convex state after the bending process (S20) by gravity bending or the like is reversed, that is, the glass sheets are turned over.

[0036] In the manufacturing method according to the first embodiment (FIG. 3), the bent glass sheet after the above-mentioned scratching (Sc) is cleaned with a cleaning liquid (S32) and dried (S33).

[0037] Furthermore, as shown in Fig. 3, the glass plate that has been through the cleaning step (S30) is subjected to a lamination step (S40). In the lamination step (S40), the two glass plates that have been overlapped and bent in the bending step (S20) are laminated again via an interlayer film and combined (S41). Thereafter, the two glass plates are pre-pressurized under normal or reduced pressure (S42), and then are fully pressed under high temperature and high pressure (S43) to obtain the laminated glass 1 (Fig. 2).

[0038] In the case of a wounding tool (rotating flap, non-rotating flap) equipped with the above-mentioned sheet-like flap different from the rotating brush 161, the material of the sheet-like flap may be synthetic resin (including plastic and foamed resin), natural material, etc. More specifically, the sheet-like flap may be in the form of a resin sheet formed by extrusion molding or the like, or a fiber structure formed by gathering fibers three-dimensionally or two-dimensionally, and may be felt, cloth (including woven fabric and knitted fabric), nonwoven fabric, paper, etc. When the sheet is made of resin or the material of the sheet contains resin, specific examples of the resin include ultra-low density polyethylene, linear low density polyethylene, low density polyethylene, high density polyethylene, polypropylene, polystyrene, polyurethane, silicone resin, ethylene vinyl acetate (EVA), and olefin-based elastomer.

[0039] At least the portion of the sheet-like flap that comes into contact with the glass plate may be smooth, or may have fine irregularities formed thereon, such as an arithmetic mean roughness Ra of 0.02 μm or more and 100 μm or less as specified in JIS B 0601-2013. Such fine irregularities may be inherent to the material (such as irregularities formed by the arrangement of fibers in a fiber structure). In addition, at least the portion of the surface or end face of the sheet-like flap that comes into contact with the glass plate may be roughened, or may be formed by attaching and fixing fine powder, or by kneading powder into the material such as resin during molding.

[0040] (Manufacturing method according to the second embodiment) FIG. 6 is a flow diagram showing an example of a method for manufacturing a laminated glass for automobile windows according to the second embodiment. The manufacturing method of the second embodiment shown in FIG. 6 includes the flat glass sheet preparation step (S10), the bending step (S20), the cleaning step (S30), and the lamination step (S40) similar to the manufacturing method according to the first embodiment (FIG. 3). However, as shown in FIG. 6, the second embodiment differs from the first embodiment in that the timing of scratching (Sc) is not performed before cleaning with a cleaning liquid (S32), but is performed together with cleaning with a cleaning liquid (S32). The other steps may be the same as those of the first embodiment. That is, the basic steps of the flat glass sheet preparation step (S10), the bending step (S20), the cleaning step (S30), and the lamination step (S40) in the second embodiment may be the same as those of the first embodiment.

[0041] In the cleaning step (S30), the two overlapping glass sheets are separated (S31), and then transported to a cleaning device (cleaning means) for cleaning with a cleaning liquid (S32). The cleaning means is not particularly limited as long as it is configured to remove dirt and the like attached to the surface of the glass sheet by pouring or spraying a cleaning liquid onto the surface of the glass sheet.

[0042] In the manufacturing method according to the second embodiment, in the cleaning with a cleaning liquid (S32), for example, an abrasive is mixed in the cleaning liquid in advance, and the pressure with which the cleaning liquid is sprayed onto the convex surface of the glass plate is adjusted to perform scratching. The above method using a cleaning liquid containing an abrasive is preferable in that it is possible to reduce the effort and cost required for scratching (Sc) by simply adding an abrasive to a commonly used cleaning means without introducing an additional scratching device.

[0043] The abrasive may contain inorganic powder or organic powder, or both, but inorganic powder is preferred because it has a high scratching effect. Examples of inorganic powder include cerium oxide, glass beads, titanium oxide, diamond, calcium carbonate, anhydrous silicic acid, sodium hydrogen phosphate, silicon nitride, silicon carbide, and aluminum oxide. Among these, cerium oxide is preferred because it has high hardness and a high scratching effect due to chemical reaction with glass. The above powders can be used alone or in combination of two or more. The median diameter (D50) of the powder used, measured by the method (wet) described in JIS Z 8825:2013, may be preferably 0.1 μm or more and 100 μm or less, more preferably 0.2 μm or more and 30 μm or less, and even more preferably 0.2 μm or more and 15 μm or less. When the powder particle size (median diameter) is 0.1 μm or more, the polishing effect can be improved and the uniformity of the in-plane strength distribution can be promoted. When the powder particle size (median diameter) is 100 μm or less, the occurrence of scratches that would impair the robustness required for the glass plate or the resulting laminated glass during the scratching treatment (Sc) can be avoided.

[0044] FIG. 7 shows a schematic cross-sectional view of an apparatus for performing cleaning (S32) with a cleaning liquid and scratching (Sc) used in the second embodiment. FIG. 7 is a cross-sectional view of the cleaning means 170 cut along the orthogonal direction Dv perpendicular to the conveying direction Dt. The cleaning means 170 has a space that is closed to a certain extent so that the cleaning liquid does not splash out to the outside, and one or more cleaning liquid jet nozzles 171, 171, ... may be provided inside. The cleaning liquid jet nozzles 171, 171, ... can jet the cleaning liquid containing the above-mentioned abrasive. The position of the cleaning liquid jet nozzles 171, 171, ..., the spread of the jetted cleaning liquid, etc. can be adjusted so that the cleaning liquid hits the entire concave surface F2 of the glass sheet G.

[0045] The cleaning liquid may refer to the main cleaning liquid containing a cleaning agent such as a surfactant, a rinsing liquid for removing the cleaning agent, or both. In this example, the abrasive may be contained in the main cleaning liquid together with the cleaning agent, or may be contained in the rinsing liquid. However, it is preferable that the surface of the curved glass sheet is finally rinsed with a rinsing liquid that does not contain an abrasive.

[0046] In this embodiment, the curved glass sheet G is transported in a convex state (with the concave surface facing downward) (FIG. 7). This embodiment is preferable in that the cleaning liquid is less likely to accumulate on the concave surface during cleaning (S32) using the cleaning liquid. If the cleaning liquid accumulates on the concave surface, the abrasive in the cleaning liquid tends to adhere to the surface of the glass sheet and remain there, and it tends to take a long time to dry the cleaning liquid, especially the rinsing liquid. However, according to this embodiment, the effort and time required for removing the remaining abrasive and drying it can be saved.

[0047] Furthermore, in this second embodiment, rather than incorporating an abrasive in the cleaning liquid beforehand as described above, the abrasive may be sprayed or applied to the concave surface F2 of the glass plate G, and then the cleaning liquid may be poured onto the concave surface F2 of the glass plate G or sprayed toward the concave surface F2.

[0048] Whether the cleaning liquid contains an abrasive in advance as described above, or the cleaning liquid is used after an abrasive is applied to the surface of the glass plate, the spray pressure of the cleaning liquid may be 0.2 MPa or more and 2 MPa or less.

[0049] In the second embodiment, the cleaning liquid may be poured or sprayed, and the wounding tool as described in the first embodiment may be used.

[0050] (Manufacturing method according to the third embodiment) FIG. 8 is a flow diagram showing an example of a method for manufacturing a laminated glass for automobile windows according to the third embodiment. The manufacturing method of the third embodiment shown in FIG. 8 has the same flat glass sheet preparation step (S10), bending step (S20), cleaning step (S30), and lamination step (S40) as the manufacturing method according to the first embodiment (FIG. 3) and the manufacturing method according to the second embodiment (FIG. 6). However, as shown in FIG. 8, the third embodiment differs from the first embodiment and the second embodiment in that the timing of scratching (Sc) is not the cleaning step (S30) but the subsequent lamination step (S40). Other points may be the same as the second embodiment and the third embodiment. That is, the basic steps of the flat glass sheet preparation step (S10), bending step (S20), cleaning step (S30), and lamination step (S40) in the third embodiment may be the same as the first embodiment and the second embodiment.

[0051] The lamination step (S40) includes, as described above, laminating two curved glass sheets with an interlayer film therebetween (S41), pre-pressing them under normal pressure or reduced pressure (S42), and then heating and pressing them to perform full pressure bonding (S43). The pre-pressing (S42) may be a process for removing air from between the glass sheets and the interlayer film before the full pressure bonding (S43) to enhance the adhesion between the glass sheets. In this embodiment, the pre-pressing (S42) can be performed, for example, by nipping a laminate consisting of two curved glass sheets laminated with an interlayer film between a pair of nip rollers to remove air that may be contained between the glass sheets.

[0052] 8, in the manufacturing method according to the third embodiment, the scratching (Sc) can be performed simultaneously with the preliminary pressure bonding (S42). Therefore, the scratching (Sc) can be performed without introducing additional equipment, and therefore the effort and cost required for scratching can be reduced.

[0053] FIG. 10 shows an example of a preliminary pressure-bonding means 180 using a nip roller. More specifically, FIG. 10 shows a state in which a laminate 1a, which is formed by laminating the vehicle exterior glass sheet 10 and the vehicle interior glass sheet 20 curved in the bending process (S20) with an intermediate film 30 interposed therebetween, is conveyed in a conveying direction Dt while being sandwiched between a pair of nip rollers 181 and 182. There may be only a pair of nip rollers, or a plurality of nip rollers may be formed in the conveying direction Dt as shown in FIG. 10. The nip pressure of the nip rollers may be 0.2 MPa or more and 0.6 MPa or less. In this embodiment, of such a pair of nip rollers 181 and 182, a scratching function may be imparted to the surface of the roller 181 that contacts the concave surface (corresponding to the fourth surface 22 in FIG. 2) of the laminate 1a.

[0054] The nip roller 181 may include, for example, a shaft body 181b and a pressure body 181a attached around the shaft body 181b, and the nip roller 182 may similarly include a shaft body 182b and a pressure body 182a attached around the shaft body 182b. In the example shown in FIG. 10, both of the pressure bodies 181a and 182a may be formed of an elastic material such as rubber, and fine irregularities may be formed on the surface of the pressure body 181a having a scratching function. Such fine irregularities can be formed by roughening the surface of the pressure body 181a, adhering and fixing a fine powder to the surface of the pressure body 181a, or wrapping a sheet having a roughened surface around the surface of the pressure body 181a. The degree of roughness of the resulting roughened surface will vary depending on the type of glass plate to be scratched, the size and shape of the glass plate, etc., but may be an arithmetic mean roughness Ra of 0.02 μm or more and 100 μm or less as specified in JIS B 0601-2013.

[0055] In the example shown in FIG. 10, the laminate 1a is transported in a downwardly convex orientation, that is, with the concave surface of the laminate 1a facing upward. As described in the second embodiment, in the cleaning step (S30), the concave surface of the curved glass sheet faces downward to prevent the cleaning liquid from accumulating. Therefore, when performing the preliminary pressure bonding (S42) in the arrangement shown in FIG. 10, it is preferable to reverse the upside down of the curved glass sheet or the laminate, that is, turn it over, after the cleaning step (S30) and before the preliminary pressure bonding (S42). However, the preliminary pressure bonding (S42) may be performed with the concave surface of the laminate 1a facing downward. In that case, the nip roller 181 having a scratching function is arranged below the laminate 1a.

[0056] Further, the nip roller 181 may be a roller that contacts the entire laminate 1a, but may have a configuration in which a plurality of separated pressure-bonding bodies 181a, 181a, ... are arranged on a shaft 181b in the axial direction of the shaft 181b as shown in Fig. 1. This increases the degree of freedom of movement of the separated pressure-bonding bodies 181a, 181a, ... relative to each other, so that they can follow the curvature of the laminate 1a along the orthogonal direction Dv.

[0057] After the preliminary pressure bonding (S42) is completed, the laminate 1a is subjected to the main pressure bonding (S43). The main pressure bonding (S43) is performed by heating the laminate 1a at a temperature of 100° C. to 150° C. under a pressure of 0.6 MPa to 1.3 MPa. For example, an autoclave can be used for the main pressure bonding (S43).

[0058] The scratching (Sc) performed in the manufacturing method according to the first to third embodiments is a process for making the strength of the glass sheet more uniform in the plane. Therefore, it can be said that this scratching process (Sc) is a process for suppressing the distribution or variation of the strength of the flat glass sheet in the plane. In other words, it can be said that it is a process for adjusting the distribution of strength values ​​(fracture stress or bending strength) measured in a plurality of regions in the plane of the glass sheet so as to narrow the distribution. In addition, the scratching performed in the manufacturing method according to this embodiment can maintain a strength that satisfies sufficient robustness as window glass. Therefore, for example, when the surface of the glass sheet is divided into a plurality of regions, the strength of each region is measured, and the frequency distribution of the strength is obtained, the result is that the distribution region with high strength is shifted in the direction of low strength by the scratching process, and the position of the distribution region with low strength does not change much.

[0059] More specifically, when the distribution of strength of the concave surface of the bent glass sheet before and after scratching (Sc) is obtained, the reduction rate R of the average value of the top 20% of the strength distribution of the concave surface of the bent glass sheet due to scratching (Sc) is U20 is 10% or more, preferably 20% or more, and the reduction rate R of the average value of the bottom 10% of the strength distribution of the concave surface of the bent glass sheet due to the damage (Sc) is L10 The damage can be made so that the damage is 30% or less, preferably 20% or less. Decrease rate R U20 (%)={(fb U20 -fa U20 ) / fb U20}×100 fb U20 : Average value of the top 20% of the strength distribution of the concave surface before damage fa U20 : Average value of the top 20% of the strength distribution of the concave surface after damage Decrease rate R L10 (%)={(fb L10 -fa L10 ) / fb L10}×100 fb L10 : Average value of the bottom 10% of the strength distribution of the concave surface before damage fa L10 : Average value of the bottom 10% of the strength distribution of the concave surface after damage The method for measuring the above strength is not particularly limited as long as the measurement conditions are the same before and after the scratching, but it can be measured and calculated by a method using R30 in accordance with ISO1288-5 (2016) described below. In this embodiment, since the fracture stress of the curved region is measured, the predetermined formula described in the ISO is not used, but an approximation formula is derived by stress measurement, and the fracture stress value can be obtained by substituting the measured value into the approximation formula. In the following, the fracture stress of the concave or convex surface is measured and calculated in the same manner using the approximation formula.

[0060] In this manner, the scratching process (Sc) in this embodiment can be performed so that the average value of the top 20% or more of the intensity distribution is significantly reduced, i.e., the number of areas with excessively high intensity is reduced, and the average value of the bottom 10% or less of the intensity distribution, i.e., the intensity of the low-intensity areas, is not excessively low or the number of such areas is not excessively increased.

[0061] Furthermore, when the distribution of the strength of the concave surface before and after the scratch (Sc) was calculated, the average of the top 20% of the strength distribution of the concave surface before the scratch (fb U20 ) and the average of the top 20% of the strength distribution of the concave surface after damage (fa U20 ) difference (fb U20 -fa U20 ) is 50 MPa or more, preferably 70 MPa or more, and the average (fb L10 ) of the bottom 10% of the strength distribution of the concave surface after damage (fa L10 ) difference (fb L10 -fa L10 ) is 30 MPa or less, preferably 20 MPa or less.

[0062] In addition, when the strength distribution was calculated for the concave surface of the scratched glass plate and the convex surface on the opposite side that was not scratched, the average of the top 20% of the strength distribution on the convex surface (fx U20 ) and the average of the top 20% of the concave intensity distribution (fv U20 ) and the difference (fx U20 -fv U20) is 50 MPa or more, preferably 70 MPa or more, and the average (fx L10 ) and the average of the bottom 10% of the intensity distribution on the concave surface (fv L10 ) and the difference (fx L10 -fv L10 ) is 30 MPa or less, preferably 20 MPa or less.

[0063] In the method according to ISO1288-5 (2016), the glass plate to be tested is placed on a support ring having a predetermined diameter, and a load is gradually increased from above the support ring using a load ring having a predetermined diameter smaller than the support ring, and the load at the time of breakage is measured. The load is applied from the opposite side of the surface to which the strength is to be determined. Then, from the measured values ​​obtained, the fracture stress value is calculated based on the predetermined formula described in ISO1288-5 (2016). Here, to calculate the strength distribution within the surface, the glass plate is cut and divided into a predetermined size, and the fracture stress can be measured for each divided area. In this case, the size of the glass after division (cutting out) is not particularly limited, but may be 60 mm to 300 mm x 60 mm to 300 mm. In addition, the number of divided samples for calculating the strength distribution may be preferably 30 or more, more preferably 50 or more. In the above measurement and calculation, the predetermined formula described in the above ISO is not used, and an approximation formula is derived by stress measurement, and then the fracture stress value can be calculated by substituting the measured value into the approximation formula.

[0064] <Laminated glass for automobile windows> Another embodiment of the present invention may be a laminated glass obtained by the above-mentioned production method. More specifically, the laminated glass for automobile windows is formed by bonding an exterior glass plate 10 and an interior glass plate 20 via an interlayer 30, and may satisfy one or more of the following conditions 1 to 3 when the exterior surface of the exterior glass plate 10 is designated as a first surface 11, the interior surface of the exterior glass plate 10 is designated as a second surface 12, the exterior surface of the interior glass plate 20 is designated as a third surface 21, and the interior surface of the interior glass plate 20 is designated as a fourth surface 22 (FIG. 2).

[0065] Condition 1: The average value of the top 20% of the intensity distribution on the first surface 11 (S1 U20) and the average value of the top 20% of the intensity distribution of the fourth surface 22 (S4 U20 ) and the difference (S1 U20 -S4 U20 ) is 50 MPa or more, preferably 70 MPa or more, and the average value (S1 L10 ) and the average value of the bottom 10% of the intensity distribution of the fourth surface 22 (S4 L10 ) and the difference (S1 L10 -S4 L10 ) is 50 MPa or less, preferably 30 MPa or less. Condition 2: The average value of the top 20% of the intensity distribution on the first surface 11 (S1 U20 ) and the average value of the top 20% of the intensity distribution on the second surface 12 (S2 U20 ) and the difference (S1 U20 -S2 U20 ) is 50 MPa or more, preferably 70 MPa or more, and the average value (S1 L10 ) and the average value of the bottom 10% of the intensity distribution on the second surface 12 (S2 L10 ) and the difference (S1 L10 -S2 L10 ) is 50 MPa or less, preferably 30 MPa or less. Condition 3: The average value of the top 20% of the intensity distribution on the third surface 21 (S3 U20 ) and the average value of the top 20% of the intensity distribution of the fourth surface 22 (S4 U20 ) and the difference (S3 U20 -S4 U20 ) is 50 MPa or more, preferably 70 MPa or more, and the average value (S3 L10 ) and the average value of the bottom 10% of the intensity distribution of the fourth surface 22 (S4 L10 ) and the difference (S3 L10 -S4 L10 ) is 50 MPa or less, preferably 30 MPa or less.

[0066] The strengths under Conditions 1 to 3 above may be fracture stresses measured by a method conforming to ISO1288-5 (2016) by applying a load from the surface opposite to the surface for which the strength distribution is to be obtained. When measuring the strengths of the second surface 12 on the interior side of the exterior glass sheet 10 and the fourth surface 22 of the interior glass sheet 20, the exterior glass sheet 10 and the interior glass sheet 20 are separated from each other in a laminated glass state and the interlayer 30 is removed before measurement. Of the measurements performed under Conditions 1 to 3 above, when determining the value under Condition 1, the strength can be measured without the need to destroy the laminated glass structure.

[0067] By satisfying one or more of the above conditions 1 to 3, it is possible to obtain a laminated glass in which both areas with excessively high strength and areas with excessively low strength are reduced or eliminated within at least one of the second surface 12 and the fourth surface 22, that is, a laminated glass in which the strength within the surface is uniform and which also has sufficient strength as window glass. Therefore, according to this embodiment, it is possible to provide a laminated glass for automobile windows which can appropriately break and absorb the impact when it receives an impact from outside the vehicle, thereby ensuring the physical protection performance of pedestrians, etc. even when a pedestrian, etc., is hit from outside the vehicle, and which also has sufficient robustness as an automobile window glass.

[0068] Among the above conditions 1 to 3, it is preferable that at least condition 2 is satisfied. When condition 2 is satisfied, the strength of the second surface 12, which is most susceptible to impact when the laminated glass receives an impact from outside the vehicle, is uniformized, and areas with excessively high strength are reduced or eliminated. This allows the laminated glass to break appropriately and improves the impact absorption effect, thereby further improving the body protection performance of pedestrians and the like in the event of a collision with a pedestrian and the like.

[0069] The laminated glass for automobile windows according to this embodiment may be a laminated glass for automobile windows 1 (FIG. 2) in which an exterior glass sheet 10 and an interior glass sheet 20 are joined via an interlayer 30, and the average value of the top 20% of the fracture stress distribution in the transmission region, measured by a method conforming to ISO1288-5 (2016) while applying a load from the exterior of the vehicle, is 500 MPa or less, preferably 450 MPa or less. In this specification, the transmission region refers to the portion of the laminated glass for automobile windows excluding the shielding layer formed on the laminated glass for automobile windows.

[0070] Although the present invention has been described based on specific embodiments, the present invention is not limited to the above-mentioned embodiments. In addition, the individual configurations included in the above-mentioned embodiments can be combined.

[0071] This application claims priority to Japanese Patent Application No. 2021-071145, filed on April 20, 2021, the entire contents of which are incorporated herein by reference. [Explanation of symbols]

[0072] 1. Laminated glass 10. Vehicle exterior glass panel 11 Page 1 12 Side 2 20. Interior glass panel 21 Page 3 22 Page 4 30 Interlayer 100 Automobiles 150 Means of transport 160 Damaging means (first embodiment) 161 Rotating Brush 161a Brush fiber 161b Shaft body 170 Cleaning methods 171 Injection Nozzle 180 Pre-crimping means 181 Nip roller with scratching function 182 Nip roller 181a, 182a Crimp body 181b, 182b shaft body F2 Concave surface of curved glass sheet Dt Transport direction Dv: Orthogonal to the conveying direction G bent glass sheet

Claims

1. A method for producing laminated glass for automobile windows, comprising: a bending step of heating and bending two glass sheets; and a lamination step of laminating the two bent glass sheets together via an interlayer film, the method for producing laminated glass for automobile windows further comprises scratching the concave surface of at least one of the two glass sheets after the bending step.

2. 2. The method for producing a laminated glass for an automobile window according to claim 1, wherein the scratching is carried out by bringing a scratching tool into contact with the concave surface of the at least one glass sheet and moving the scratching tool relatively to the concave surface.

3. A cleaning step of cleaning the two bent glass sheets after the bending step and before the bonding step is included; The method for producing a laminated glass for an automobile window according to claim 1 or 2, wherein the scratching is carried out before the bonding step.

4. A cleaning step of cleaning the two bent glass sheets after the bending step and before the bonding step is included; The method for producing a laminated glass for an automobile window according to claim 1 or 2, wherein the scratching is carried out in the cleaning step.

5. The method for producing a laminated glass for an automobile window according to claim 4, wherein the scratching is carried out by spraying a cleaning liquid containing an abrasive.

6. 5. The method for producing a laminated glass for an automobile window according to claim 4, wherein the scratching is carried out by applying an abrasive to the concave surface of at least one of the glass plates and then cleaning the concave surface with a cleaning liquid.

7. 5. The method for producing a laminated glass for an automobile window according to claim 4, wherein in the cleaning step, the concave surface of the at least one glass plate faces downward.

8. The method for producing a laminated glass for an automobile window according to claim 1 or 2, wherein the concave surfaces of the two glass plates are scratched.

9. The lamination step includes a preliminary pressure-bonding step of preliminarily bonding the laminate obtained by laminating the two glass plates via an interlayer film under normal pressure or reduced pressure to obtain a preliminary pressure-bonded body; and a final pressure bonding step of performing final pressure bonding of the pre-bonded body under high temperature and high pressure to obtain a laminated glass, The method for producing a laminated glass for an automobile window according to claim 1 or 2, wherein the scratching is performed by scratching a concave surface of the laminate in the preliminary pressure-bonding step.

10. The preliminary pressure-bonding is performed by a plurality of rollers that sandwich the laminate, The method for producing a laminated glass for an automobile window according to claim 9, wherein a surface of the roller facing the concave surface of the laminate is roughened.

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