Patent Application
20240416625
The invention relates to a laminated glass for an automobile window, and to an automobile.
There is a need for a technology to reduce, when an automobile collides with a person such as a pedestrian, an impact on the person. For example, Japanese Unexamined Patent Application Publication No. 2017-213928 discloses a technology to reduce an impact on a person when an impact is applied around a cowl louver and a windshield, by separating the rear end of the cowl louver connected by a molding from the front end of the windshield.
A laminated glass for automobile windows, such as windshields, is required to break properly in order to reduce, when an automobile collides with a person such as a pedestrian, the impact on the person. For example, a laminated glass for automobile windows is required to have a head injury criterion (HIC) of a desired value or less. A laminated glass for automobile windows is also required to enable an occupant of the vehicle to see the outside of the vehicle through the laminated glass for automobile windows. An object of an aspect of the present invention is to reduce an impact on a person when an automobile collides with the person, while not obstructing the visibility of the outside of the automobile by the occupant of the automobile.
According to an aspect of the present disclosure, a laminated glass for an automobile window, the laminated glass including a first glass plate, an intermediate film, and a second glass plate in this order from outside of a vehicle to inside of the vehicle, is provided. A plurality of heterogeneous regions formed by a laser are provided in a vicinity of a surface of the first glass plate, a surface of the second glass plate, or the surfaces of the first glass plate and the second glass plate, the surfaces facing the inside of the vehicle, being spaced apart in a plane direction a ratio of a length in a thickness direction to a circle equivalent diameter in plan view of the heterogeneous regions is 2 or more and 1,000 or less.
According to another aspect of the present disclosure, a laminated glass for an automobile window, the laminated glass including a first glass plate, an intermediate film, and a second glass plate in this order from outside of a vehicle to inside of the vehicle, is provided. A plurality of heterogeneous regions formed by a laser are provided in a vicinity of a surface of the first glass plate, a surface of the second glass plate, or the surfaces of the first glass plate and the second glass plate, the surfaces facing the inside of the vehicle, being spaced apart in a plane direction, a ratio of a length in a longitudinal direction to a diameter of a cross section perpendicular to the longitudinal direction of the heterogeneous regions is 2 or more and 1,000 or less.
According to an aspect of the present disclosure, it is possible to provide a technology that reduces an impact on a person when an automobile collides with the person, while not obstructing the visibility of the outside of the automobile by the occupant of the automobile.
Other objects and further features of the present disclosure will be apparent from the following detailed description when read in conjunction with the accompanying drawings, in which:
In the following, embodiments will be described with reference to the drawings. In each of the drawings, the same or corresponding components are denoted by the same reference numerals, and the description thereof may be omitted.
The material constituting the first glass plate 10 and the second glass plate 20 (hereinafter also referred to together simply as glass plates) in the laminated glass 1 is preferably inorganic glass. Examples of the inorganic glass include soda lime silicate glass, aluminosilicate glass, borate glass, lithium aluminosilicate glass, borosilicate glass, and the like. The method of forming the glass plate made of the inorganic glass is not particularly limited, but the glass plate is preferably glass (float glass) formed by a float method, for example.
The glass plate used for manufacturing the laminated glass 1 may be unreinforced glass (raw glass). The unreinforced glass is glass obtained by molding molten glass into a plate shape and slowly cooling the molten glass, and is not subjected to a strengthening treatment such as an air-cooling strengthening treatment or a chemical strengthening treatment. By using the unreinforced glass, even when the glass cracks due to impact, the entire surface will not be shattered into small pieces, ensuring the visibility for the occupant even in the event of an accident.
The thickness of the first glass plate 10 and the second glass plate 20 may be the same or different from each other. The thickness of the first glass plate 10 may be 1.1 mm or more and 3.5 mm or less. The thickness of the second glass plate 20 may be 0.5 mm or more and 2.3 mm or less. The overall thickness of the laminated glass 1 may be 2.3 mm or more and 8.0 mm or less. The configurations (material constituting the glass plate, manufacturing method of the glass plate, and the like) of the first glass plate 10 and the second glass plate 20 may be the same or different from each other.
The material of the intermediate film 30 is not particularly limited, but is preferably a thermoplastic resin. Examples of the material of the intermediate film 30 include conventional thermoplastic resins such as plasticized polyvinyl acetal resin, plasticized polyvinyl chloride resin, saturated polyester resin, plasticized saturated polyester resin, polyurethane resin, plasticized polyurethane resin, ethylene-vinyl acetate copolymer resin, ethylene-ethyl acrylate copolymer resin, cycloolefin polymer resin, and ionomer resin. A resin composition containing a modified block copolymer hydride disclosed in Japanese Patent No. 6065221 can also be suitably used. Among these, the plasticized polyvinyl acetal resin is preferably used because of its excellent balance of various properties such as transparency, weather resistance, strength, adhesive strength, penetration resistance, impact energy absorption, moisture resistance, heat shielding, and sound insulation. The above-mentioned thermoplastic resin may be used alone or in combination of two or more. The term “plasticized” in the plasticized polyvinyl acetal resin means that it is plasticized by the addition of a plasticizer. The same applies to other plasticized resins.
The intermediate film 30 may be a resin containing no plasticizer, such as an ethylene-vinyl acetate copolymer resin, for example. Examples of the polyvinyl acetal resin include a polyvinyl formal resin obtained by reacting polyvinyl alcohol (PVA) with formaldehyde, a polyvinyl acetal resin in a narrow sense obtained by reacting PVA with acetaldehyde, a polyvinyl butyral resin (PVB) obtained by reacting PVA with n-butyraldehyde, and the like. In particular, PVB is a preferred material because of its excellent balance of various properties such as transparency, weather resistance, strength, adhesive strength, penetration resistance, impact energy absorption, moisture resistance, heat shielding, and sound insulation. The above-mentioned resin may be used alone or in combination of two or more.
The intermediate film 30 may have either a single-layer structure or a multi-layer structure. The intermediate film 30 may have a function other than adhesion. For example, the intermediate film 30 may have one or more layers selected from a sound insulating layer, a colored transparent layer, an ultraviolet ray cutting layer, an infrared ray cutting layer, and the like.
The thickness of the intermediate film 30 may be 0.5 mm or more from the viewpoint of adhesion. The thickness of the intermediate film 30 may be 3 mm or less from the viewpoint of lightness and handleability. The thickness of the intermediate film 30 may be constant or may vary depending on the position.
The method of manufacturing the laminated glass 1 includes, for example, steps (a) to (c) below. (a) The first glass plate 10 and the second glass plate 20 are stacked together with the intermediate film 30 interposed therebetween to produce a laminate. (b) The laminate is housed in a container such as a rubber bag, and the inside of the container is heated while being depressurized, and the first glass plate 10 and the second glass plate 20 are bonded together with the intermediate film 30. The internal pressure of the container is, for example, −100 kPa to −65 kPa based on atmospheric pressure. The heating temperature of the container is, for example, 70° C. to 110° C. (c) The laminate taken out from the container is pressure-bonded at a pressure of 0.6 MPa to 1.3 MPa while being heated at 100° C. to 150° C. For the pressure-bonding, for example, an autoclave is used. The method of manufacturing the laminated glass 1 may be any general method and need not necessarily include the step (c) above.
As illustrated in
The first glass plate 10 and the second glass plate 20 are bent before the step (a). The bending is performed in a state where the glass is softened by heating. The heating temperature of the glass at the time of the bending is, for example, 550° C. to 700° C. The first glass plate 10 and the second glass plate 20 may be bent separately or stacked and simultaneously bent. The bending may include gravity forming or press forming, and may include both.
A shielding layer or a light shielding layer 40 may be provided on the peripheral edge of the laminated glass 1 for protecting a sealant or the like that adheres and holds the laminated glass 1 to the vehicle body (
As described above, the laminated glass 1 for automobile windows is required to break properly in order to reduce, when an automobile collides with a person such as a pedestrian or a cyclist, the impact on the person. For example, the laminated glass 1 is required to have a head injury criterion (HIC) of a desired value or less (for example, 1,000 or less, preferably 650 or less).
Here, a description will be given of how the laminated glass 1 cracks upon impact with a person. As illustrated in
In the laminated glass 1 according to the present embodiment, the first glass plate 10 and/or the second glass plate 20 have a plurality of heterogeneous regions formed spaced apart in the plane direction of the glass plate at a position in the vicinity of the surface facing the inside of the vehicle, that is, at a position on the surface facing the inside of the vehicle, or at a position inside the first glass plate 10 and/or the second glass plate 20 and a depth position close to the surface facing the inside of the vehicle. In other words, a plurality of heterogeneous regions are formed at intervals in the plane direction in a region close to the second surface F2 inside the first glass plate 10, and/or a plurality of heterogeneous regions (or heterogeneous phases) are formed at intervals in the plane direction in a region close to the fourth surface F4 inside the second glass plate 20. The heterogeneous regions in the present embodiment are formed by heterogenization by irradiation with laser beam (described later).
In the present specification, the term “heterogeneous region (or heterogeneous phase)” means a minute region in which glass is locally heterogenized in a glass plate, and the heterogenization means locally changing physical and/or chemical properties. In the present specification, the heterogeneous region may be a region in which one or more properties of virtual temperature, density, refractive index, stress, crystalline state, composition, ionic valence, and cavity formation are locally changed by irradiation with laser beam (described later). Therefore, the heterogenized region may be a region including cracks, dents, bubbles, and the like. Further, the heterogeneous region may be, for example, a region in which the virtual temperature is higher than the value before the heterogenization, specifically, a region in which the virtual temperature has changed by 30° C. or more from the value before the heterogenization. The virtual temperature can be evaluated by spectroscopic evaluation such as Raman spectroscopy or infrared spectroscopy. The heterogeneous region may be a region in which the refractive index is lower or higher than the value before the heterogenization, for example, a region in which the refractive index has changed by 0.1% or more with the value before the heterogenization being 100%.
In the present embodiment, the heterogeneous region is formed at a position close to the surface, among the surfaces of the glass plate, facing the inside of the vehicle on which cracking occurs first when the laminated glass 1 receives an impact from the outside. Therefore, the heterogeneous region serves as a starting point of cracking, making it easier for the glass plate to start cracking, thereby facilitating proper cracking of the laminated glass 1. In addition, because a plurality of heterogeneous regions 50 are provided in the vicinity of the surface facing the inside of the vehicle and spaced apart in the plane direction, a surrounding compressive stress generated against the tensile stress in the heterogeneous region 50 appears on the surface (the surface facing the inside of the vehicle), and a continuous tensile stress is generated over the entire surface between the compressive stresses appeared on the surface, thereby reducing the strength of the surface as a whole and making the surface susceptible to cracking. Therefore, even when an automobile collides with a person, the laminated glass 1 can absorb the impact by cracking, and the impact sustained by the person can be reduced. In the present embodiment, the difference in the plane stress value between the heterogeneous region and the peripheral region in the surface facing the inside of the vehicle (the second surface F2 and/or the fourth surface F4) of the glass plate can be 0.2 MPa or more and 20 MPa or less.
In the present embodiment, as long as the heterogeneous regions are formed in either of the first glass plate 10 and the second glass plate 20, the effect that the laminated glass 1 can break properly as described above can be obtained. However, when the heterogeneous regions are formed at least in the side of the second glass plate 20 that is not in contact with the intermediate film 30 and is exposed to the outside (the inside of the vehicle), the laminated glass 1 can be effectively weakened. Further, when the heterogeneous regions are formed in both of the first glass plate 10 and the second glass plate 20, each of the first glass plate 10 and the second glass plate 20 is likely to crack from the inside of the vehicle, so that the laminated glass 1 as a whole is likely to break properly and cracks are likely to develop in the thickness direction, which is preferable.
A pitch P1 of the first heterogeneous regions 51, 51, . . . is preferably 1 mm or more and 200 mm or less, more preferably 10 mm or more and 100 mm or less, and still more preferably 20 mm or more and 100 mm or less. The pitch P1 is a distance between the center position of one first heterogeneous region 51 and the center position of another first heterogeneous region 51 arranged closest to each other. The pitch P1 may be constant over the transparent region 5 or may vary depending on the position, and in the latter case, the pitch P1 is an average value. By setting the pitch P1 to 1 mm or more, it is possible to minimize the phenomenon that the first heterogeneous regions 51, 51 are too close to each other and the compressive stress generated on the surface is continuously distributed in the plane direction, causing the glass plate to be less susceptible to cracking. By setting the pitch P1 to 200 mm or less, the starting point of the cracking are suitably distributed on the surface facing the inside of the vehicle (the second surface F2) of the first heterogeneous regions 51, 51, . . . , and the laminated glass 1 is likely to break properly when an impact is applied to the laminated glass 1 from the outside of the vehicle.
A pitch P2 of the second heterogeneous region 52 is similar to the pitch P1 of the first heterogeneous regions 51, 51, . . . , and may preferably be 1 mm or more and 200 mm or less, more preferably 10 mm or more and 100 mm or less, and still more preferably 20 mm or more and 100 mm or less. The effect of setting the pitch P2 of the second heterogeneous region 52 to 1 mm or more and 200 mm or less is also similar to the effect regarding the surface facing the inside of the vehicle with respect to the pitch P1.
The heterogeneous region 50 may or may not extend to the surface facing the inside of the vehicle (the second surface F2 or the fourth surface F4) of the glass plate in which the heterogeneous region 50 is formed. That is, the heterogeneous region 50 may or may not appear on the surface facing the inside of the vehicle. However, it is preferable that the heterogeneous region 50 is in contact with the surface facing the inside of the vehicle or the heterogeneous region 50 appears on the surface facing the inside of the vehicle, from the viewpoint that the starting point of the cracking is likely to occur on the surface facing the inside of the vehicle and tensile stress is likely to occur on the surface facing the inside of the vehicle. Meanwhile, from the viewpoint of ensuring the robustness of the laminated glass 1 during normal use without collision, it is preferable that the heterogeneous region 50 does not appear on the surface facing the inside of the vehicle depending on the shape and size of the heterogeneous region 50.
As schematically illustrated in
A length L in the thickness direction of the heterogeneous region 50 (
A maximum circle equivalent diameter D (
A ratio (L/D) of the length L in the thickness direction to the maximum circle equivalent diameter D of the heterogeneous region 50 may be 2 or more and 1,000 or less, preferably 2.5 or more and 500 or less, more preferably 2.5 or more and 100 or less, still more preferably 3 or more and 100 or less, still more preferably 5 or more and 100 or less, and particularly preferably 10 or more and 50 or less. When the value (L/D) of the heterogeneous region 50 is 2 or more, the effect that the laminated glass 1 can break properly at the time of collision can be improved. When the value (L/D) is 1,000 or less, the robustness as an automobile window in normal use without collision can be ensured. Moreover, the visibility of the outside by the occupant of the automobile 100 is not obstructed.
Further, the length Li of the heterogeneous region 50 in the longitudinal direction (
A diameter Di of the cross section perpendicular to the longitudinal direction of the heterogeneous region 50 (
The aspect ratio of the heterogeneous region 50, that is, the ratio (Li/Di) of the length Li in the longitudinal direction to the diameter Di may be 2 or more and 1,000 or less, preferably 2.5 or more and 500 or less, more preferably 2.5 or more and 100 or less, still more preferably 3 or more and 100 or less, still more preferably 5 or more and 100 or less, and particularly preferably 10 or more and 50 or less. When the value (aspect ratio) of the (Li/Di) of the heterogeneous region 50 is 2 or more, the effect that the laminated glass 1 can break properly at the time of collision can be improved. When the value of the (Li/Di) is 1,000 or less, the robustness as an automobile window can be ensured during normal use without collision. Moreover, the visibility of the outside by the occupant of the automobile 100 is not obstructed.
In the example illustrated in
The longitudinal direction of the elongated heterogeneous region 50 may be parallel to the thickness direction (the normal direction when the glass plate is curved) as illustrated in
From the viewpoint of effective weakening of the laminated glass 1, the longitudinal directions of the plurality of heterogeneous regions 50 may preferably be aligned parallel to the thickness direction or to the normal direction. From the viewpoint of improving the visibility of outside of the automobile by scattering external light incident on the heterogeneous regions in various directions, the longitudinal directions of the plurality of heterogeneous regions 50 may preferably not be aligned but may be different, and more preferably the angle θ may be distributed within a range of more than 0° and 60° or less. As another example, from the viewpoint of ensuring the visibility by making the heterogeneous regions themselves less visible, the longitudinal directions of the elongated heterogeneous regions 50 may be parallel to the horizontal direction when assembled in the automobile. Further, the longitudinal directions may also be parallel to the direction along the line of sight toward the laminated glass 1 from the eye position of the occupant, in the state of being assembled to the automobile. Accordingly, the size of the heterogeneous regions in the view of the occupant can be minimized, thereby reducing the influence on the visibility.
In the heterogeneous region 50 in which the cracks 50c are formed around the central heterogeneous portion 50a, the length L in the thickness direction of the heterogeneous region 50 may be the length from the surface facing the inside of the vehicle of the glass plate to the deepest position where the cracks 50c extend, and the circle equivalent diameter D of the heterogeneous region 50 in plan view may be the diameter of the smallest circle in which the range in which the cracks 50c extend is contained in plan view.
The central heterogeneous portion 50a is a portion directly formed by laser irradiation for forming the heterogeneous region 50, and may have a diameter Da close to the laser irradiation diameter. In contrast, the cracks 50c may be formed during or immediately after the central heterogeneous portion 50a is formed by laser irradiation. When the central heterogeneous portion 50a is a recess, the recess may be an ablation portion formed by laser ablation.
The circle equivalent diameter Da in plan view of the central heterogeneous portion 50a, that is, the diameter of a circle having the same area as the area of the central heterogeneous portion 50a in plan view, may be preferably 10 μm or more and 200 μm or less, and more preferably 20 μm or more and 100 μm or less. The length La in the thickness direction of the central heterogeneous portion 50a may be preferably more than 0 μm and 200 μm or less, and more preferably 5 μm or more and 50 μm or less. The ratio (La/Da) may be preferably 1 or less, and more preferably 0.8 or less. The lower limit of (La/Da) is not particularly limited, but (La/Da) may be more than 0, and for example, 0.05 or more.
The position in the thickness direction (depth position) of the heterogeneous region 50 is preferably 0 μm or more and 200 μm or less from the surface facing the inside of the vehicle. The depth position refers to a length from the surface facing the inside of the vehicle to an end of the heterogeneous region 50 near the surface facing the inside of the vehicle, in the thickness direction. When the depth position is 0 μm, the heterogeneous region 50 reaches the surface facing the inside of the vehicle. When the heterogeneous region 50 reaches the surface facing the inside of the vehicle, it is preferable because it can perform its function better on the surface of the glass plate and promotes proper cracking at the time of collision.
One or more of the following may be the same or different between the first heterogeneous region 51 and the second heterogeneous region 52: shape, the length L in the thickness direction, the maximum circle equivalent diameter D, the length Li in the longitudinal direction and the diameter Di of the heterogeneous region itself, and the tilt angle θ and the distribution states thereof.
When the glass plates 10 and 20 constituting the laminated glass 1 are float glass, the heterogeneous regions 50, 50, . . . are preferably formed in the vicinity of the surface (hereinafter referred to as bottom surface) that was in contact with molten metal, for example, molten tin or molten tin alloy at the time of manufacture, among the two main surfaces of the glass plate 10. This point will be described below.
The float method is a method of forming molten glass by floating it on molten metal such as molten tin in a float bath. Here, the bottom surface that was in contact with the molten tin contains tin in the vicinity of the surface, while the top surface, which is the main surface on the opposite side of the bottom surface, that was not in contact with the molten tin contains almost no tin. On the top surface that contains almost no tin, ion exchange reaction between sodium ions in the glass and hydrogen ions in the outside air proceeds, and a surface hydration layer is gradually formed. Because the hardness of the surface hydration layer is low, the fragility of the top surface decreases over time, and cracks are less likely to form and grow. Therefore, even when the heterogeneous regions 50, 50, . . . are formed on the top surface side, the fracture strength increases over time. As a result, it may be difficult for the laminated glass 1 to initiate cracking when a person such as a pedestrian collides with an automobile, and the function of protecting a person may not be sufficient. In contrast, on the bottom surface containing tin, the ion exchange reaction between hydrogen ions and sodium ions is inhibited by the effect of tin, which is an asymmetric ion, and the formation of the surface hydration layer is difficult to proceed. Therefore, by forming the heterogeneous regions 50, 50, . . . in the vicinity of the bottom surface, the fracture strength does not readily change over time, and the function of protecting a person can be maintained for a long period of time.
From the above, in the present embodiment, it is desirable to form the heterogeneous regions 50, 50, . . . in the vicinity of the bottom surface containing a large amount of tin. In the manufacturing of the laminated glass 1, it is preferable that the glass plates 10 and 20 are arranged so that the surfaces facing the inside of the vehicle (the second surface F2 and the fourth surface F4) respectively become the bottom surfaces. In addition, in the bottom surface containing a large amount of metal such as tin, the light absorption particularly in the UV region is significantly improved. Therefore, when the heterogeneous regions 50, 50, . . . are formed, by performing the laser irradiation from the bottom surface side, there is also an advantage that the processing can be performed with lower energy irradiation.
The bottom surface that contains a large amount of tin and the top surface that contains almost no tin can be discriminated by measuring the tin concentration on both surfaces using, for example, a tin surface measuring instrument TinCheck manufactured by Bohle Ltd. On the bottom surface, a tin containing layer having a thickness of 5 to 15 μm can be detected by quantitatively measuring the tin concentration using an X-ray fluorescence method or an EPMA method.
When obtaining the distribution of the strength (fracture stress) (calculation method will be described later) of the surface facing the inside of the vehicle (the second surface F2 and/or the fourth surface F4) of the glass plate of the laminated glass 1 obtained according to the present embodiment, the maximum value of the strength may be preferably 350 MPa or less, and more preferably 250 MPa or less. The minimum value of the strength may be preferably 60 MPa or more, and more preferably 80 MPa or more. When the maximum value is 350 MPa or less, the laminated glass 1 is likely to crack at the time of collision, and the effect of reducing the impact on a person can be improved. When the minimum value is 60 MPa or more, the destruction of the laminated glass 1 by flying gravel can be decreased.
As described above, the heterogeneous regions 50, 50, . . . are formed using a laser. Because the laser beam has a high directivity or convergence property and can irradiate a small spot diameter (diameter at a focusing position), the heterogeneous region 50 can be formed with a precise size and arrangement by locally heating a minute region.
The laser beam LB is emitted under a condition that the inside of the glass plate can be focused. More specifically, the laser beam LB is emitted under a condition that the inside of the first glass plate near the second surface F2 and/or the inside of the second glass plate near the fourth surface F4 can be focused. Accordingly, the inside of the glass plate is preferentially heated, and a minute region inside the glass plate can be heterogenized to form the heterogeneous region.
In the emitting of the laser beam LB, nonlinear absorption may be used or linear absorption may be used. When the nonlinear absorption is used, the photon density may be 1×108 W/cm2 or more and 1×1014 W/cm2 or less. In the nonlinear absorption, multiphoton absorption occurs. The probability of the multiphoton absorption in the nonlinear absorption dramatically increases with higher photon density. For example, the probability of two-photon absorption is proportional to the square of the photon density. In the case of the nonlinear absorption, by selecting a wavelength with small linear absorption, it is possible to selectively absorb light only in the condensing section, so that the heterogeneous region 50 is readily formed deep inside the glass plate.
In the linear absorption, one-photon absorption occurs at an arbitrary position in the thickness direction of the glass plate depending on the photon density. The one-photon absorption is proportional to the photon density. In addition, the intensity of the laser beam LB is attenuated according to Lambert-Beer's law. That is, when the intensity of the laser beam LB changes from I0 to I while the laser beam LB travels a distance E (unit [cm]) through the glass plate, the equation I=I0×exp (−α×E) is established, where the absorption coefficient of the glass plate is α (unit [cm−1]). From the viewpoint of absorbing the laser beam LB inside the glass plate, it is preferable to irradiate the laser beam LB so that the absorption coefficient α is more than 0 and less than 100. In the case of the linear absorption, even for colored glass, for example, the size and shape of the heterogeneous region 50 can be readily controlled by appropriately selecting the absorption coefficient α. In the case of the linear absorption, the heterogeneous region appearing on the surface of the glass plate is readily formed.
The wavelength of the laser beam LB, although it depends on the composition or the like of the glass plate included in the laminated glass 1, is preferably such that the laser beam LB can be at least partially transmitted so that the inside of the glass plate can be heated as described above. More specifically, the wavelength of the laser beam LB may be 250 nm or more and 5,000 nm or less, and preferably 310 nm or more and 3,000 nm or less. In the above wavelength range, the absorption coefficient α can be set in an appropriate range, and the presence or absence of ablation, the degree of ablation, and the like can be adjusted.
Examples of the light sources of the laser beam include near-infrared lasers such as Yb fiber lasers (wavelength: 1,000 nm or more and 1, 100 nm or less), Yb disk lasers (wavelength: 1,000 nm or more and 1, 100 nm or less), Nd:YAG lasers (wavelength: 1,064 nm), and high-power semiconductor lasers (wavelength: 808 nm or more and 980 nm or less). The light sources of the laser beam may be UV lasers (wavelength: 310 nm or more and 360 nm or less), green lasers (wavelength: 510 nm or more and 540 nm or less), Ho:YAG lasers (wavelength: 2,080 nm), Er:YAG lasers (2, 940 nm), lasers using mid-infrared parametric oscillators (wavelength: 2, 600 nm or more and 3,450 nm or less), and the like. An LD pumped solid state (diode pumped solid state, DPSS) laser combined with a wavelength conversion element may be used.
The laser beam LB may be emitted using a pulse oscillation method or a continuous oscillation method. The pulse oscillation method is preferable from the viewpoint of reducing unintended damage to the vicinity of the irradiation portion. The operation mode of the pulse is not particularly limited, but a burst pulse mode is preferable because high-output irradiation can be performed and the irradiation time can be shortened. In the case of the pulse oscillation method, a nanosecond pulse laser, a picosecond pulse laser, a femtosecond pulse laser, or the like can be used.
Other conditions for laser beam irradiation may be 0.0001 ns or more and 100 ns or less, a pulse energy of 10 μJ or more and 1,000 μJ or less, a number of irradiations of 1 or more and 1,000 times or less, and a repetition frequency of 1 kHz or more and 10,000 kHz or less. The irradiation angle of the laser beam (the angle with respect to the direction normal to the main surface of the glass plate at the irradiation position) can be set to an irradiation angle corresponding to the tilt angle θ (
When the heterogeneous regions 50, 50, . . . are formed, the laser beam is intermittently irradiated to a plurality of predetermined positions while moving the relative position of the laser beam LB to the laminated glass 1. For example, the laser beam irradiation device 300 can be scanned in the plane direction while fixing the position of the laminated glass 1. In this case, it is preferable to use a scanner (scanning device) such as a galvano-scanner or a polygon scanner. Because the irradiation position of the laser beam LB can be arbitrarily changed three-dimensionally by using the scanning device, it is possible to reliably irradiate the laser beam LB at a predetermined position even on a curved glass plate, for example.
When forming the heterogeneous regions on both the first glass plate 10 and the second glass plate 20, the laser beam LB is scanned over the transparent region 5 to form the first heterogeneous regions 51, 51, . . . in the first glass plate 10, and then the laser beam LB is scanned over the transparent region 5 again to form the second heterogeneous regions 52, 52, . . . in the second glass plate 20. The formation order of the first heterogeneous regions 51, 51, . . . and the second heterogeneous regions 52, 52, . . . may be reversed.
The scanning of the laser beam LB required to obtain the laminated glass 1 as the final product is one time, and the heterogeneous regions may be formed in both the first glass plate 10 and the second glass plate 20. In this case, during one scanning, the laser beam LB is condensed at two or more different positions in the optical axis direction, that is, both in the first glass plate 10 and the second glass plate 20. Specifically, it is preferable to condense and irradiate the laser beam LB using a multifocal lens or a multifocal diffractive optical element. Thus, the time required for the scanning of the laser beam LB can be shortened. This method is suitable for obtaining a configuration (
As illustrated in
In the laminated glass 1 according to the present embodiment, ablation by the laser beam may occur, and for example, as described with reference to
In the laminated glass 1 according to the present embodiment, the arithmetic mean roughness Ra of the roughness curve specified in JIS B 0601-2013 of the second surface F2 of the first glass plate 10 and the fourth surface F4 of the second glass plate 20 can be 0.1 nm or more and 1,000 nm or less at least in the transparent region 5.
As described above, the heterogeneous region 50 in the laminated glass 1 according to the present embodiment may be a region including the central heterogeneous portion 50a and the cracks 50c formed around the central heterogeneous portion (
Here, the formation of the cracks in the heterogeneous region 50 having the cylindrical central heterogeneous portion 50a as an example will be described with reference to
Thus, because the laminated glass 1 includes the cracks 50c arising from the central heterogeneous portion 50a, the initiation of cracking at the time of collision between an automobile and a person is further promoted, and the effect that the laminated glass 1 can break properly can be improved.
According to an embodiment of the present invention, a method of manufacturing a glass plate for an automobile window is provided. The method includes: forming a plurality of heterogeneous regions by a laser in a vicinity of a surface of the glass plate in the glass plate, the surfaces facing the inside of the vehicle, being spaced apart in a plane direction, wherein a ratio of a length in a thickness direction to a circle equivalent diameter in plan view of the heterogeneous regions is 2 or more and 1,000 or less.
According to an embodiment of the present invention, a method of manufacturing a laminated glass for an automobile window, the laminated glass comprising a first glass plate, an intermediate film, and a second glass plate in this order from outside of a vehicle to inside of the vehicle, is provided. The method includes: forming a plurality of heterogeneous regions by a laser in a vicinity of surfaces of the first glass plate and/or the second glass plate, the surfaces facing the inside of the vehicle, being spaced apart in a plane direction, wherein a ratio of a length in a thickness direction to a circle equivalent diameter in plan view of the heterogeneous regions is 2 or more and 1,000 or less.
According to an embodiment of the present invention, a method of manufacturing a laminated glass for an automobile window, the laminated glass comprising a first glass plate, an intermediate film, and a second glass plate in this order from outside of a vehicle to inside of the vehicle, is provided. The method includes: forming a plurality of heterogeneous regions by a laser in a vicinity of surfaces of the first glass plate and/or the second glass plate, the surfaces facing the inside of the vehicle, being spaced apart in a plane direction, wherein a ratio of a length in a longitudinal direction to a diameter of a cross section perpendicular to the longitudinal direction of the heterogeneous regions is 2 or more and 1,000 or less.
In the method of manufacturing a laminated glass for an automobile window, the forming of the heterogeneous regions may be performed after the first glass plate and the second glass plate are overlapped with each other via the intermediate film. In this case, the irradiation conditions of the laser beam, particularly the wavelength of the laser beam, are adjusted such that the absorption of the laser beam in the first glass plate and/or the second glass plate is larger than the absorption of the laser beam in the intermediate film. According to the method, when the first heterogeneous regions 51, 51, . . . are formed in the first glass plate 10 and the second heterogeneous regions 52, 52, . . . are formed in the second glass plate 20, the displacement of the plates in a plan view can be prevented.
Furthermore, in the method of manufacturing a laminated glass for an automobile window, the laser beam may be irradiated after the first glass plate and the second glass plate irradiated with the laser beam are bent. Accordingly, it is possible to prevent the shape and size of the heterogeneous regions 50, 50, . . . from being affected in the bending process and the function of the heterogeneous regions 50, 50, . . . from becoming non-uniform depending on the positions in the plane direction.
Experimental data will be described below. In the following experimental examples, Examples 1 to 5 are examples, and Example 6 is a comparative example.
A glass sample (100 mm×100 mm×2 mm thickness) was cut out from a glass plate having a composition of soda-lime silicate glass obtained by the float method in the same manner as in a commonly used mass production process, and laser irradiation was performed at one location in the center of the plane of the glass sample from the top surface side. Thus, one heterogeneous region was formed in the vicinity of the bottom surface of the glass sample. Table 1 presents laser irradiation conditions. In the irradiation conditions, “number of irradiation” is the number of times of the laser irradiation. “angle of irradiation” is an angle with respect to the direction normal to the top surface (Example 1) or the bottom surface (Examples 2 to 5) of the glass plate at the irradiation position. When the irradiation angle is 0°, it means that the laser is irradiated in the direction normal to the incident plane (the top surface or the bottom surface). In Example 1, the heterogeneous region was formed by laser irradiation at an irradiation angle of 0°.
The laser processing apparatus used for laser irradiation consists of a laser beam irradiation device (LD pumped solid state laser) and a galvano-scanner as a scanning device. The laser processing apparatus capable of irradiating laser beams at various angles was used although the apparatus itself is fixed in position. The aperture and working distance of the lens were set so that the spot diameter of the laser beam on the glass plate surface was 32 μm in 1/e2 diameter.
The glass sample after laser irradiation was put into an electric heating furnace, and heat treatment was performed at 658° C. for 200 seconds as a heat treatment equivalent to the commonly performed bending process.
Glass samples of Examples 2 to 5 were obtained in the same manner as in Example 1 except that the laser irradiation conditions were changed as presented in Table 1 (including that the incident plane of the laser was set to the bottom surface). In Example 5, a heterogeneous region was formed by laser irradiation at an irradiation angle of 28.00°. Thus, a heterogeneous region in which the axial direction was tilted by 17.78° with respect to the direction normal to the glass plate surface was obtained.
A glass sample was obtained in the same manner as in Example 1 except that the laser irradiation was not performed.
Heterogeneous regions formed in the vicinity of the bottom surface of the glass samples of Examples were photographed from the side of the bottom surface where the heterogeneous regions were formed using a digital microscope VHX-6000 manufactured by Keyence corporation. The diameter Di of the heterogeneous regions was determined based on the photographed images. Further, the contour of the heterogeneous regions in the cross section cut in the thickness direction of the glass plate was determined by one-dimensional analysis using a laser microscope VK-X3000 manufactured by Keyence corporation, and the length Li of the heterogeneous regions was determined based on the analysis. In Examples 1 to 4, because the heterogeneous regions are not tilted, the length Li in the longitudinal direction of the heterogeneous regions is the same as the length L in the thickness direction, and the diameter Di of the cross section perpendicular to the longitudinal direction of the heterogeneous regions is the same as the circle equivalent diameter D in plan view. The results are presented in Table 1.
Ten glass samples (100 mm×100 mm×2 mm thickness) manufactured as described above were prepared, and the strength of each glass sample was measured as fracture stress (MPa). The fracture stress was measured by R30 in accordance with ISO 1288-5 (2016). Specifically, using a support ring of 60 mm diameter and a load ring of 12 mm diameter, a load was applied by the load ring at a load speed of 0.3 mm per minute, and the fracture load was measured. The load was applied from the top surface side of the glass plate with the load ring arranged on the top surface side. The fracture stress was obtained using the equation described in ISO 1288-5 (2016). The results are presented in Table 1.
The maximum value and the minimum value were recorded from the data of strength of the above ten glass samples, and the average value was calculated and recorded.
As presented in Table 1, in Examples 1 to 5 in which the heterogeneous regions were provided having the shape in which the ratio (Li/Di) of the length to the diameter is 2 to 1,000, the maximum value of the fracture stress was 350 MPa or less, and the minimum value was 60 MPa or more. In contrast, in Example 6 in which the heterogeneous regions were not provided, the maximum value of the fracture stress was over 350 MPa.
A glass sample (300 mm×300 mm×2 mm thickness) was cut out from a glass plate having a composition of soda lime silicate glass obtained by the float method, and laser irradiation was performed from the top surface side (Example 1) or from the bottom surface side (Examples 2 to 5). The irradiation was performed intermittently at 81 points scattered in a square grid pattern of 30 mm pitch. The laser irradiation conditions were as presented in Table 1. The glass sample after the laser irradiation was put into an electric heating furnace, and heat treatment was performed at 658° C. for 200 seconds as a heat treatment equivalent to the commonly performed bending process.
Two glass samples subjected to the laser irradiation and the heat treatment were laminated with an intermediate film (PVB resin) interposed therebetween in such a manner that the bottom surfaces of the glass samples face the same direction (so that the bottom surfaces of both glass samples face upward) and pressed together to form a laminated glass. A laminated glass sample was obtained in which a glass sample having a thickness of 2 mm, an intermediate film having a thickness of 0.76 mm, and a glass sample having a thickness of 2 mm were laminated. In Example 6, a laminated glass sample was obtained in the same manner as in Examples 1 to 5 except that the laser irradiation was not performed.
The obtained laminated glass was installed at a position 400 mm away from the evaluator with the surface facing the inside of the vehicle of the glass plate facing the evaluator's face. The visibility of the image on the opposite side of the laminated glass (outside of the vehicle) under natural light was evaluated. The evaluation criteria were as follows.
The evaluation of each Example is presented in Table 1.
According to the above, it has been found that the laminated glasses for automobile windows of Examples 1 to 5, in which a plurality of heterogeneous regions formed by a laser are provided in a vicinity of the surfaces of the first glass plate and/or the second glass plate, the surfaces facing the inside of the vehicle, being spaced apart in a plane direction, can provide a technology that reduces an impact on a person when an automobile collides with the person, while not obstructing the visibility of the outside of the automobile by the occupant of the automobile.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2022-032932 | Mar 2022 | JP | national |
The present application is a continuation application of International Application No. PCT/JP2023/007860, filed Mar. 2, 2023, which claims priority to Japanese Patent Application No. 2022-032932 filed Mar. 3, 2022. The contents of these applications are incorporated herein by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2023/007860 | Mar 2023 | WO |
| Child | 18817130 | US |
