JPS6317778B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a laminated glass made by laminating thin glass sheets of 1.5 mm to 2.5 mm. Laminated glass is made by laminating two glass plates with a plastic interlayer film such as polyvinyl butyral film.
It is especially widely used as windshields for automobile windshields. For example, the standard laminated glass for automobiles is a combination of two glass plates with a thickness of about 2.5 mm to 5 mm. There has been a demand for the development of thin laminated glass for automobiles using thin sheet glass from the viewpoint of reducing the weight of automobiles and ensuring safety for occupants in the event of a collision. However, in the case of laminated glass made of laminated glass sheets of 2.5 mm or less, the impact on the edges of the laminated glass during manufacturing, transporting the laminated glass, or handling such as fitting it into a car window This often caused breakage, making it extremely difficult to handle and impractical. In order to overcome these difficulties, laminated glass, in which thin glass plates are strengthened and the tempered glasses are laminated, has also been proposed. However, for glass sheets of 2.5 mm or less, the currently common method of strengthening glass sheets by air cooling has the disadvantage that sufficient strengthening cannot be achieved due to insufficient cooling capacity. Therefore, when strengthening glass sheets of 2.5 mm or less, special strengthening methods such as ion exchange strengthening methods and liquid cooling strengthening methods must be used, which not only requires a huge amount of equipment but also takes time. In addition, it has the disadvantage that it is inconvenient to handle during strengthening, has a low yield, and therefore cannot rapidly produce inexpensive laminated glass on a mass production basis. The object of the present invention is to provide a laminated glass that does not have the above-mentioned drawbacks, can be mass-produced at low cost, and has characteristics that are optimal for automobile windshields. . As a result of research based on this purpose, the inventor has
Under normal conditions, the stress generated in the edge part due to impact during handling such as fitting is mostly 170Kg/cm ²
As a result of repeated experiments, statistics show that simply setting the planar compressive strength of the peripheral area to 200 kg/cm ² will have almost no problem in practical handling and will significantly reduce damage. I found it. The present invention is based on such knowledge, and the thickness of the two glass plates of laminated glass, which is made by laminating two glass plates with a plastic interlayer film, is 1.5 mm or more.
2.5 mm, and a plane compressive stress of 200Kg/cm ² to 350Kg/cm ² is formed at the periphery of the outer surface of each glass plate of the laminated glass. The plane tensile stress of the plane of the inner region is 80Kg/cm ² or less. According to the present invention, a plane compressive stress of 200 Kg/cm ² to 350 Kg/cm ² is applied to the periphery of the outer surface of the glass plate to improve the edge strength, so that when fitting the glass plate into an automobile window, Alternatively, damage during transportation can be significantly reduced. Moreover, since the laminated glass of the present invention has almost no cross-sectional strain in the thickness direction of the two glass plates, even if it breaks when used for the front window of a car, it will not be as strong as ordinary fully tempered glass. As there are no cracks in the entire surface, the driver's forward visibility can be secured. Furthermore, conventional air-cooling strengthening equipment cannot apply cross-sectional strain to the entire 1.5 mm to 2.5 mm glass plate by air-cooling strengthening, but conventional bending equipment cannot apply plane compressive strain only to the peripheral area. Alternatively, it can be carried out simply by improving the air-cooling reinforcement equipment, so that reinforcement can be carried out inexpensively, in large quantities, and easily. Furthermore, according to the present invention, two sheets can be bent and subjected to plane compressive stress at the same time by the method described below, which is not only advantageous in processing operations, but also makes it possible to narrow the desired shape when heated with one sheet. Even 1.5 mm to 2.5 mm thick glass plates, which are difficult to bend under their own weight, can be formed into a desired shape without the above-mentioned difficulties because two sheets are stacked and bent. Furthermore, since two glass plates are stacked to cool the peripheral area, there is less distortion in the cross-sectional direction of the glass plate, and it is possible to apply the desired plane compressive strain only to the peripheral area of the outer surface of the glass plate where strength is required. The shapes can be molded with high precision so that they match well when combined. The present invention will be explained in detail below. In the present invention, the two glass plates constituting the laminated glass have sufficiently satisfactory properties such as rigidity, flatness, secondary distortion, and strength, and can be used in various bending processes. 1.5mm that can be
A glass plate with a thickness in the range from 2.5 mm to 2.5 mm is advantageously selected. When the thickness of the glass plate is 2.5 mm or more, laminated glass increases rigidity and strength, making it difficult to break in a collision, so there is a possibility of serious injury due to impact, and collision safety is reduced. At the same time, if you try to apply strain to the periphery using the method described below, the strain may extend to the cross-sectional direction of the glass plate, increasing the strength, reducing collision safety and reducing the risk of damage in the event of breakage. This is undesirable because it makes it impossible to secure forward visibility. On the other hand, the thickness of the glass plate is 1.5mm
If it is below, it is unsatisfactory in terms of rigidity, flatness, secondary distortion, strength, etc., and cannot be used as a base glass for laminated glass. When such a glass plate is constructed into a laminated glass, a plane compressive stress in the range of 200 Kg/cm ² to 350 Kg/cm ² is applied at least to the periphery of the glass plate on the outer side. . At least on the outer periphery of the glass plate, the laminated glass plate should be able to protect the edges from impact during transportation or fitting into the window, and also have sufficient strength even after being fitted into the window. In order to hold the glass plate, it is necessary to apply a plane compressive stress of at least 200 Kg/cm ² or more to the peripheral area of about 1.5 cm from the edge of the glass plate. Furthermore, when the two glass plates used as base glass for the laminated glass are configured into a laminated glass,
The plane tensile stress formed on the inner surface of the glass plate adjacent to the peripheral area where the plane compressive stress is formed on the outer surface of each glass plate is
It is preferably 80Kg/cm ² or less. If 80
If there is a plane tensile stress of Kg/cm ² or more, the laminated glass will be more likely to break when an impact is applied to its outer surface, reducing safety and making it unsatisfactory from a practical standpoint. In particular, in curved laminated glass, if the outer surface of the convex glass plate has a plane tensile stress of 80 kg/cm ² or more, it becomes more likely to break. The above 80Kg/ ^cm2 or less plane tensile stress inside the periphery is the plane compressive stress of the periphery 350
It can be obtained by controlling the amount to be less than Kg/cm ² . This is because plane compressive stress in the peripheral area is only applied to the very peripheral area within 15 mm of the glass plate, especially within 10 mm.
This is because, for example, in a glass plate of 0.7 m ² or more, the plane tensile stress corresponding to the plane compressive stress can be suppressed to 80 Kg/cm ² or less. It has been mentioned that when constructed into laminated glass, a plane compressive stress of 200 Kg/cm ² to 350 Kg/cm ² is formed in the periphery of the surface facing the outside of each glass plate. 200Kg/cm ² ~ on the periphery of the inner surface of each glass plate, that is, the surface in contact with the plastic interlayer film.
A plane compressive stress of 350 Kg/cm ² may be applied. The above-mentioned glass to which plane compressive stress is applied to the peripheral portion is optimally manufactured by the following method. For example, two glass plates are placed one on top of the other with an anti-fusing agent interposed therebetween, and placed on a bending die prepared to bend the two sheets into a desired shape. Next, the glass plate is placed in a heating furnace, heated to 590°C to 605°C, and bent into a shape according to the bending die using its own weight. Next, when cooling this heated glass plate, the slow cooling range temperature is between 450°C and 550°C at 90°C/min.
Air is blown from above and below or from the sides of the periphery of the two stacked glass plates so that the glass plates are cooled at a cooling rate of 130°C/min, preferably 100°C/min to 120°C/min, or Alternatively, the glass plate may be transferred to a cooling chamber or the heated glass plate may be taken out of the heating furnace and allowed to cool. By doing this, 200Kg/cm ^{2 ~} is applied only to within 15mm of the outer periphery of the two glass plates.
A plane compressive stress of 350Kg/cm ² can be applied, and a plane tensile stress of 80Kg/cm ² or less can be applied to the inside of the periphery. In addition, slow cooling range temperature 450℃~550℃
If the cooling rate is below 900℃/ ^min between
Also, if the cooling rate is higher than 130℃/min, the plane tensile stress generated in the center of the glass part cannot be suppressed to less than 80Kg/ ^cm2 , and in some cases, the glass plate may warp or deform. This occurs, making it impossible to obtain a material suitable for laminated glass. If the glass plate is rapidly cooled using this method, there will be no cross-sectional strain in the thickness direction of the glass plate, and only plane compressive stress will be applied to the periphery, making it the ideal glass plate for automobile front laminated glass. can provide something. The two reinforced glass plates at the periphery are placed with their plane compressive stress surfaces facing outward.
A plastic interlayer film such as a polyvinyl butyral film or a polyurethane interlayer film is sandwiched between them to prepare a laminated glass assembly. Next, this laminated glass assembly is prepared and integrated by a conventional laminated glass assembly bonding method. For example, place the laminated glass assembly in a pre-crimping bag and reduce the pressure to 500 to 650 mmHg.
Heat to 80-90℃ and pre-compress. Next, the pre-compressed laminated glass assembly is placed in an autoclave and heated to 120 to 145°C under a pressure of 12 to 14 kg/cm, held for about 15 to 30 minutes, and then main pressure bonding is performed to bond the glass plate and plastic. A laminated glass is manufactured by bonding and integrating the interlayer film. Example Thickness 2.0 cut to dimensions of 633 mm long x 1342 mm wide
We prepared 11 sets consisting of two mm glass plates.
Two of each set of glass plates were stacked and placed on a bending mold for self-weight bending, and the temperature near the outlet was measured at A in Table 1.
Place each glass plate in a heating furnace set to various temperatures as shown in the column, heat the glass plate to 590°C to 605°C, and bend it under its own weight into the desired shape. Next, the temperature near the entrance of the heated two-ply glass plate was adjusted to B in Table 1.
The periphery of each glass plate was cooled at various cooling rates as shown in column C of Table 1 in the slow cooling temperature range of 450°C to 550°C. This produced a plane compressive stress. The results of measuring the planar compressive stress (indicating the average value of several points) in the peripheral area of each glass plate are shown in column D of Table 1. In addition, this plane compressive stress only extended to an area of 10 mm from the periphery. Furthermore, the results of measuring the plane tensile stress at the center of each glass plate are shown in the right column of Table 1. In this way, two glass plates were stacked one on top of the other, and a 0.76 mm thick polyvinyl butyral film was sandwiched between the two glass plates, each of which had a planar compressive stress applied to its periphery, with the plane compressive stress generating surface facing outward. The laminated glass pre-assembly is made by stacking, which is then placed in a pre-crimping bag and the pressure is reduced to 600 mmHg, heated to 85°C, and the laminated glass pre-assembly is pre-bonded. Next, this was placed in an autoclave, heated to 130℃ under a pressure of 13Kg/cm ² , and held for 20 minutes to perform main pressure bonding to bond the glass plate and polyvinyl butyral membrane, and integrate them. manufactured glass. The bottom column of Table 1 shows the results of a static pressure load test conducted on 11 sets of laminated glass made under various conditions in this way. In addition, Comparative Example 1 in Table 1 is a laminated glass in which two glass plates with a thickness of 2.5 mm and which are not subjected to plane compressive stress at the peripheral part are laminated with a polyvinyl butyral film of 0.76 mm according to the above method as in the present invention. be. This 2.5mm glass plate
Laminated glass made of 0.76PVB-2.5mm glass plates has been considered to be the limit of practical thickness until now, but the laminated glass of the present invention has a static pressure load resistance of the same level or higher than this. is recognized. In addition, Comparative Example 2 is a glass plate 2 in which plane compressive stress is not applied to the periphery of the plate having a thickness of 2.0 mm as in the present invention.
It is a laminated glass made by laminating sheets of glass with a 0.76 mm polyvinyl butyral film according to the method described above.

[Table] In the static pressure load test, as shown in Figure 3, the laminated glass was placed on two support rods near the edges of the laminated glass with the convex portion facing upward. A 1Kg hammer was placed one after another on the laminated glass, and the load at the time the laminated glass plate broke was measured. Of the prototypes in Table 1, prototype numbers No. 1 and No.
4. Figure 4 shows the results of measuring the stress distribution diagram around the periphery of the glass plate No. 10.
In the figure, solid line A is No. 4, dotted line B is No. 1, -
The dashed dotted line shows the stress distribution curve for each prototype No. 10. The vertical curve indicates the stress value and the horizontal axis indicates the distance from the edge of the glass plate. As is clear from Fig. 4, the plane compressive stress in the peripheral area of the glass plate is within 10 mm from the edge of the glass plate, and the plane compressive stress forming area of the glass plate where the plane compressive stress is formed in this peripheral area. The plane tensile stress generated on the inner surface is 80 Kg/cm ² or less, and furthermore, it is recognized that the stress is 0 inside this region.

[Brief explanation of the drawing]

FIG. 1 shows a glass plate with plane compressive stress applied to the periphery, which is used in the laminated glass of the present invention.
FIG. 2 shows a cross-sectional view of the laminated glass of the present invention,
FIG. 3 shows the method of a static pressure load test, and FIG. 4 is a distribution diagram of plane stress in the peripheral area of the laminated glass of the present invention. 1: Glass plate, 2: Planar compressive stress area at the periphery, 3: Plastic interlayer film, 4: Stainless steel, 5: Laminated glass, 6: Support rod.

Claims (1)

[Claims] 1 Planar compressive stress of 200 Kg/cm ² to 350 Kg/cm ² is formed in the peripheral area of the glass plate within 1.5 cm from the edge of the glass plate, while the inner area adjacent to the peripheral area where this planar compressive stress is formed The plane tensile stress of 80
Kg/cm ² or less, two glass plates with a thickness of 1.5 mm to 2.5 mm are stacked facing each other with the surfaces on which plane compressive stress is formed facing outward, with a plastic interlayer interposed between them. Laminated glass featuring: