MXPA99002320A - Medium membrane for glass lamin - Google Patents

Abstract

The object of the present invention is to provide an intermediate film for laminated glass that does not lead to the problem of poor appearance in its lamination with glass and that can be easily produced without remodeling the existing production equipment and which is superior in productivity. The present invention relates to intermediate film for laminated glass that is used in the manufacture of laminated glass by intercalating it between two glass sheets that are placed facing each other, comprising a section profile that decreases in thickness in the manner of a curve in the axial direction of the

Description

MEDIUM MEMBRANE FOR LAMINATED GLASS TECHNICAL FIELD The present invention relates to an intermediate film for laminated glass suitable for a protective screen and its application in an automotive windshield, a process for its production, a laminated glass incorporating said intermediate film for laminated glass, a roll of intermediate film for laminated glass and a method for its manufacture.

BACKGROUND OF THE INVENTION In the front part of a motor car, an airplane or the like, the so-called windscreen, also known as front glass, is used. The front glass is usually a laminated glass film consisting of two glass sheets placed face to face and an intermediate film for laminated glass interspersed between the glass sheets. In recent years the need has arisen, from safety considerations, for a car windshield, the information generated REF .: 29745 for instruments such as the speed and other movement data of a car, for example, that can be shown on the so-called head-height display (HUD) within the same visual field of the vehicle. Driver than the windshield. In relation to the HUD mechanism, many systems have been developed so far. In a typical system, the area of the HUD screen does not exist on the surface of the windshield glass but the driver perceives the reflection of the data as a virtual image in the same position (that is, within the same visual field) as the windshield. However, since the laminated glass of the windshield consists of two parallel sheets of glass, this system has the disadvantage that the driver has a double vision of the instrument screen. To overcome this disadvantage, U.S. Patent No. 5013134 discloses a technology for placing an intermediate film having a wedge-shaped angle within the windshield glass. U.S. Patent No. 5087502 discloses a wedge-shaped sheet and a method for its manufacture. In addition, US Patent No. 5639538 discloses a sheet that is uniform in thickness over at least 20% of its total area extending from any edge thereof and gradually decreases in thickness toward the midline and which is cut or cut. It divides around the middle line. Because those intermediate films for laminated glasses have a wedge shape in section, the technologies mentioned above have the disadvantage that compensating films are often produced in the lamination with the glass and therefore the efficiency is sacrificed. In addition, since the sheet is partially uniform in thickness and wedge-shaped in the remainder, the risk is high for the incidence of rejects due to poor appearance along the edge line between the uniform part in thickness and the part that has the wedge-shaped thickness profile in the rolling process. When such an intermediate film having a wedge-shaped profile is applied to the curved, curled front glass, it is common practice to press the intermediate film together with the surface configuration of the glass, thereby making the film uniform in thickness. As typically described in the Japanese Kokai Publication Hei-3-209210, it is known that by using an intermediate film having a wedge-shaped thickness profile with its retained shape for the front glass having a screen function at the height of the head, you can form a clear reflection image without causing a double vision. Meanwhile, any intermediate film having a wedge-shaped thickness profile is wound in the manner of a roll to form a cone due to non-uniform thickness and it is necessary to vary the angle of the core according to the length of the film that it's going to roll up In addition, because the resulting roll is conical, there is naturally a limit to the length of the film that can be wound by roll so that the efficiency of the roll transport decreases and roll instability makes handling difficult. When using a tapered core to roll up, the roll is cylindrical and stable but the length of the film that can be rolled per roll decreases further to sacrifice the transport efficiency. As an intermediate film that overcomes the above advantages, Japanese Kohyo Publication Hei-7-508690 discloses an intermediate film which is uniform in thickness at a given distance from any edge of the film and decreases in thickness symmetrically from the parts mentioned first towards the film. center of the film, thus allowing the film to be formed as a cylindrical roll with a constant radius. However, the intermediate film described in the publication Kohyo Japonesa Hei-7-508690 is so complicated in its sectional configuration, that it is not easy to manufacture it, and also has the disadvantage that it is possible that wrinkles occur in the central part of the thickness thin.

BRIEF DESCRIPTION OF THE INVENICON The present invention, developed in view of the prior art, aims to provide an intermediate film for laminated glass that does not give rise to problems of poor appearance in its lamination with glass and that can be easily produced without remodeling of the equipment. existing production and that is superior in productivity. A further object of the present invention is to provide an intermediate film roll for laminated glass that overcomes the disadvantages of conventional intermediate film rolls for laminated glass and, as such, is easy to handle and contributes to transport efficiency and a process for its production. The present invention is directed to an intermediate film for laminated glass comprising forming laminated glass by sandwiching between two glass sheets that are placed face to face, and comprising a sectional profile that decreases its thickness transversely in the manner of a curved shape. The present invention is further directed to an intermediate film for laminated glass comprising forming the laminated glass by intercalation between two sheets of * glass facing each other and comprising a sectional profile having a continuum of arcs having or more radii different The present invention is further directed to a process for producing the intermediate film for laminated glass, which comprises feeding a starting composition for the intermediate film for the laminated glasses by means of a production equipment comprising an extruder, an extrusion die, a first cooling pressure roller and a second cooling pressure roller, and both rollers have respectively controlled separations in the predetermined manner. The present invention is further directed to a laminated glass obtained using the intermediate film for laminated glass of the present invention. There is no particular limitation on the kind of glass that can be used for the laminated glass of the present invention. For example, it can be an inorganic glass such as flotation glass or an organic glass such as polycarbonate glass. The roll of intermediate film for laminated glass of the present invention comprises the winding of two strips of an intermediate film for laminated film that increases in thickness transversely from one edge to the other edge as it is wound in superimposition one on the other with its edge of a strip that is thinner in thickness which is aligned with its edge of the other strip that is greater in thickness. The process for producing a roll of intermediate film for laminated glass that increases in thickness of the film from one edge to the other edge in the axial direction of the present invention comprises the winding of two continuous strips of an intermediate film in superimposition one on the another with its edge a strip that is thinner in thickness which is aligned with its edge of the other strip that is greater in thickness.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic of the production equipment for producing the intermediate film for laminated glass of the present invention. Fig. 2 is a schematic cross-sectional view showing the first cooling pressure roller in the above equipment for the production of the intermediate film for laminated glass according to this invention. Fig. 3 is a schematic cross-sectional view showing the second cooling pressure roller in the equipment for producing the intermediate film for laminated glass of the present invention. Fig. 4-1 is a sectional view showing the intermediate film for laminated glass produced by the production process of the intermediate film for laminated glass of the present invention. Fig. 4-2 is a sectional view showing the intermediate film for laminated glass produced by the production process of the intermediate film for laminated glass of the present invention. Fig. 5 is a sectional view showing an intermediate film having the wedge-shaped thickness profile. Fig. 6 is a sectional view showing an intermediate film having the wedge-shaped profile. Fig. 7 is an elementary sectional view showing an example of the roll of the intermediate film for laminated glass according to this invention. Fig. 8 is a sectional view -elementary of an intermediate film having a wedge-shaped thickness profile. Fig. 9 is a perspective view showing the extrusion die for use in the production of an intermediate film having a wedge-shaped thickness profile.

Fig. 10 is a sectional view showing the conventional roll.

BRIEF DESCRIPTION OF THE REFERENCE NAMES 1. - extruder 2.- extrusion die for molding 3.- first cooling pressure roller 4.- second cooling pressure roller 5.- auxiliary equipment 11.- core 12.- intermediate film 13.- extrusion die 131. - resin hole DESCRIPTION OF THE INVENTION Considering that it is a transparent thermoplastic resin, there is no particular limitation in the material for the intermediate film for the laminated glass of the present invention. For example, such conventional materials as the polyvinyl butyral resin, the polyurethane resin and the ethylene-vinyl acetate copolymer resin can be employed.

The intermediate film for the laminated glass of the present invention is characterized by its unique sectional profile, and such intermediate film for laminated glass is sandwiched between two sheets of glass. Thus, said sectional profile is such that the thickness of the sheet decreases in a curved manner in the axial direction thereof. In addition said profile comprises a continuum of arcs having two or more different radii. The term "decreases in the manner of a curve" means that the intermediate film for laminated glass gradually decreases in thickness along a curvature in the axial direction thereof. The term arc means a part in the circumference of a circle. The term "two or more arcs" means that said continuum consists of a plurality of arcs and excludes the case in which the continuum consists of a single arc, and a plurality of arcs differ in radius. That plurality of arcs that differ in radius means that the radius of the arc of one arc is different from the radius of another arc. Although arcs of the same arc radius may exist between said plurality of arcs, the case in which all arcs are equal in the radius of the arc is excluded. The proportion of the number of arcs that differ in radius to the total number of arcs is preferable as much as possible. The continuum of such arcs means a continuous arrangement of arcs. In other words, due to the existence of the continuity of arcs, such arcs exist in a partially superposed relation between the adjacent circles. Unlike the conventional intermediate film for laminated glasses, the intermediate film for laminated glasses having the above profile is free from the disadvantage that a compensation film often arises in the lamination process with the glass. Furthermore, compared to the prior art film which is partially uniform in thickness and wedge-shaped in the remaining part, the intermediate film for the laminated film of the present invention does not cause the problem of poor appearance along the line of the edge in the part of the uniform thickness and the part that has a wedge-shaped thickness profile in the process of lamination with the glass. The process for producing the intermediate film for the laminated glass of the present invention will now be described in detail, with reference to the accompanying drawings.

Fig. 1 is a schematic view showing typical production equipment for use in the production process of the intermediate film for laminated glass of the present invention. This production equipment comprises an extruder 1, an extrusion die 2, a first cooling pressure roll 3, a second cooling pressure roll 4 and an auxiliary equipment 5. The thermoplastic resin to be used as the material for the intermediate film for the laminated glass of the present invention is provided in the extruder 1 and was supplied in the molten state to the extrusion die 2. The molten resin, extruded in the form of sheet or sheet of this extrusion die 2, is passed through of the first cooling pressure roller 3 and further through the second cooling pressure roller 4, and finally it is wound in a fixing device. Fig. 2 shows the mechanism of action of the first cooling pressure roller 3. This first cooling pressure roll 3 is adjusted to provide a space that varies gradually from one axial end to the other, and pressures not similar to the axial ends of the roll are applied. Due to the deflection of the pressure roller in response to the applied pressures, the thickness of the film of the thermoplastic resin can be varied transversely in a continuum of arcs having two or more radii. Fig. 3 shows the mechanism of action of the second cooling pressure roller 4. This second cooling pressure roller has a separation with a gradient substantially corresponding to the transverse thickness of the thermoplastic resin film which is molded from the first cooling pressure roller and has a uniformly patterned surface. As both axial ends of the second cooling pressure roller 4 are subjected to different pressures that are not below predetermined levels, an intermediate film for laminated glass having a uniformly patterned surface can be produced. Thus, the extruded thermoplastic resin of the extrusion die is guided to the first cooling pressure roll which is arranged to have a different spacing between the two axial ends of the front roll. Different pressures are applied to said axial ends of the first cooling pressure roller respectively, whereby the resulting deflection of the roller causes the resin film to assume a wedge-shaped thickness profile in the axial direction. The film is additionally applied to the second cooling pressure roller which is arranged at a different spacing between its two axial ends and different pressures are applied to the axial ends of the roller, whereby the film is provided with a section profile which it decreases in thickness in the manner of a curve and, at the same time, it is uniformly embossed in the axial direction thereof. By the aforementioned process, the intermediate film for laminated glass of the present invention can be obtained. As mentioned above, the intermediate film for laminated glass of the present invention greatly contributes to the windshield HUD function, and the laminated glass that can be obtained using such an intermediate film for laminated glass also falls within the scope of the present invention. The roll of intermediate film for laminated glass of the present invention will now be described in detail. The material for the intermediate film for the laminated glass of the present invention is not particularly restricted but includes those materials that are conventionally used for this purpose. Thus, for example, the polyvinyl butyral resin, the ethylene vinyl acetate copolymer and the polyvinyl chloride resin can be mentioned. In this aspect of the present invention the way of increasing the thickness of the intermediate film from one edge to the other in the axial direction can be linearly incremental, ie the so-called wedge-shaped profile, or it can be increased in thickness in the manner of a curve. ~ - The ratio of change in thickness of the intermediate film is preferably from about 0.1 to 0.7 mm per meter of its width. For use as HUD, the preferred ratio of change in the thickness of the intermediate film to laminated glass is about 0.2 to 0.3 mm per meter of its width. In addition, the two intermediate film strips for laminated glass can be the same or different in the ratio of change in their thickness. The preferred thickness of the intermediate film for the laminated glass is approximately 0.3 mm in the minimum thickness position and approximately 1 mm in the maximum thickness position. If the thickness of the intermediate film for laminated glass is less than 0.3 mm, the penetration resistance of the laminated glass will be insufficient and, in addition, a relax in the film will be created under its own weight during production. On the contrary, if it exceeds 1 mm, the penetration resistance will be excessive and the disadvantage will be unavoidable in relation to the cost. Continuous intermediate film strips for the laminated glass each increased in thickness from one edge to the other in the axial direction, by adjusting the extrusion orifice of each die according to the desired film thickness or by passing the extruded strips between a pair of rolls to control the shape and / or the separation of the desired film. Where necessary, the intermediate film for laminated glass with a colored band can be provided, either locally or through its area, and such a color band can be provided by co-extrusion of a colored resin or by printing the necessary pattern on the intermediate film extruded. In the production method of an intermediate film roll for laminated glass of the present invention, two strips of the intermediate film can be extruded for laminated glass either from a single extruder or from two extruders. When two extruders are used, the two strips of the intermediate film for laminated glass do not have to be extruded concurrently but the two strips can be respectively formed into rolls and then superposed one on the other. As an alternative, an intermediate film strip for laminated glass is extruded and placed in a conical manner and the other strip is extruded and wound onto the rolls of the first strip. As a further alternative, the second intermediate film strip for laminated glass can be extruded and rolled into the superimposition or superposition of the roll of the first strip before while the latter continuously rolls up from its roll to provide a cylindrical roll. The roll of the intermediate film for laminated glass of the present invention comprises the winding of two strips of intermediate film for laminated glass, each increasing the thickness in the axial direction thereof from one edge to the other as it is rolled in overlap one in the other with its edge of a strip that is greater in thickness being aligned with its edge of the other strip that is thinner in thickness. Therefore, the resulting roll has a substantially cylindrical profile that is easy to transport and handle. In the production method of an intermediate film roll for laminated glass of the present invention, two continuous strips of an intermediate film for laminated glass are rolled in overlap one on the other with their edge of a strip that is greater in thickness being aligned with its edge of the other strip which is thinner in thickness, resulting in a roll which is a cylindrical roll with a substantially constant radius and as such, can be easily handled and transported. Fig. 7 is a schematic cross-sectional view showing an exemplary roll of intermediate film for laminated glass of the present invention. Referring to FIG. 7, the reference number 11 represents a core in which the intermediate film for laminated glass is wound to provide the roll of the present invention. The reference number 12 represents an intermediate film which, as best seen in FIG. 8, has a thickness profile that increases in thickness in the axial direction thereof from one edge to the other. As shown, two intermediate film webs 12, 12 each having such wedge-shaped thickness profile are overlapped one on top of the other with its edge of a strip 12 which is thinner in thickness and aligned with its edge. the other strip 12 that is greater in thickness. The intermediate film 12 having said wedge-shaped profile can be produced, for example by using an extrusion die 13 having a resin hole 131 with its edge of one which is greater than the other edge in thickness as shown in FIG. Fig. 9. In the roll of intermediate film for laminated glass of the present invention shown in Fig. 7, two continuous strips 12, 12 of the intermediate film each having such wedge-shaped thickness profile are overlapped one on top of the other with its edge of a strip 12 which is thinner in thickness being aligned with its edge of the other strip 12 that is greater in thickness. Therefore, the resulting roll is a roll having a substantially cylindrical profile that is easy to transport and handle. Preferred embodiments of this invention have been described above with reference to the drawings but many changes and modifications can be made by those skilled in the art without departing from the appended claims. For example, the core 11 does not always have to be employed in winding the intermediate film for laminated glass.

EXAMPLES The following examples illustrate the present invention in greater detail and those examples in no way define the scope of the present invention.

Example 1 Using the production equipment shown in Fig. 1, an intermediate film for laminated glass was produced under the following conditions.

Extrusion matrix Slot width: 1300 mm Matrix temperature: 180 ° C First cooling pressure roller Roller effective length: 2000 mm Temperature: 40 ° C Second cooling pressure roller Effective roller length: 2000 mm Separation of roll: 0.47 mm The sectional configuration of the intermediate film for laminated glass produced is shown in Figs. 4-1 and 4-2. The thickness profile and radii of the arc of this intermediate film for laminated glass are shown in Table 1. The intermediate film according to Example 1 had a thickness profile comprising a continuum of arcs having two or more different radii.

[Table 1] Comparative Example 1 Using the same production equipment that was used in Example 1, an intermediate film having the wedge-shaped thickness profile illustrated in Fig. 5 was produced. Here, the respective separations of the first cooling pressure roller and the second cooling pressure roller were adjusted so that the gradient (a) of the thickness profile in the axial direction was approximately equal to the gradient (a) according to Example 1. The thickness profile is shown in Table 2. The intermediate films for laminated glass of Example 1 and Comparative Example 1 were compared with (a) of each with respect to the compensation weight per 100 meters. The data of the respective weights are given in Table 3.

[Table 2] [Table 3] Comparative Example 2 Using the same production equipment that was used in Example 1, an intermediate film having the wedge-shaped profile illustrated in Fig. 6 was produced. Here, the respective separations of the first and second press rolls The cooling profile was adjusted so that the gradient (a ") of the thickness profile in the axial direction was substantially equal to the gradient (a) according to Example 1. The thickness profile is shown in Table 4. Xa intermediate film for The laminated glass of Example 1 and the intermediate film for laminated glass of Comparative Example 2 were used respectively in combination with flat glass sheets of 3.00 mm each to make a laminated glass Laminated glass manufactured using the intermediate film for laminated glass of the laminated glass. Comparative Example 2 was found to have been deformed.

[Table 4] Example 2 Using a plasticized polyvinyl butyral resin and a biaxial extruder and the matrix shown in Fig. 9, a first intermediate film strip having a wedge-shaped profile was produced. As shown in Fig. 8, this intermediate film for laminated glass had a thickness of 0.76 mm at one edge and a thickness of 0.8 mm at the other edge. Concurrently, using biaxial extruder and the same matrix as illustrated in Fig. 9, a second intermediate film strip having the same wedge-shaped thickness profile as the first strip was extruded. As shown in Fig. 7, the two anterior strips of intermediate film were overlapped one on the other with their edge of a strip that is thinner in thickness being aligned with its edge of the other strip that is greater in thickness and rolled up concurrently in a cylindrical core, 200 mm in outside diameter, for a total of 150 turns to provide a cylindrical roll with a constant diameter of 730 mm.

Comparative Example 3 The procedure of Example 2 was repeated to produce two intermediate film strips having the same wedge-shaped thickness profile. As shown in Fig. 10, the two strips were wound in superimposition or overlapping on a cylindrical core, 200 mm in outer diameter, with its edge of a strip, which is thinner in thickness being aligned with its edge of the another strip that is thinner in thickness for a total of 300 turns. The resulting roll was a conical roll that had a diameter of 660 mm at one end and 790 mm in diameter at the other end.

According to this invention described above, an intermediate film for laminated glass can be obtained with a greater proportion of decrease in thickness in the axial direction compared with the conventional intermediate film having a wedge-shaped thickness profile, ensuring an improved contact with glass, without incidence of poor appearance and without requiring remodeling of existing equipment.

This intermediate film for laminated glass is very suitable for screen purposes at the height of the head. The roll of intermediate film for laminated glass of the present invention consists of two strips of an intermediate film for laminated glass having a wedge-shaped thickness profile in the axial direction as it is rolled in overlapping one on the other with its edge. a strip that is thinner in thickness that is aligned with its edge of the other strip that is greater in thickness, with the result that the resulting roll is a cylindrical roll with a substantially constant radius that is easy to handle and transport. In the production method of an intermediate film roll for laminated glass of the present invention, two strips of an intermediate film for laminated glass are rolled in overlap one on the other with its edge of a strip that is thinner in thickness than is aligned with its edge of the other strip that is greater in thickness, with the result that the resulting roll is a cylindrical roll with a substantially constant radius that is easy to handle and transport. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (7)

1. - An intermediate film for laminated glass that is used in the manufacture of laminated glass by intercalating it between two glass sheets that are placed facing each other, characterized in that it comprises a section profile that decreases in thickness in the manner of a curve in the axial direction of the same.

2. - An intermediate film for laminated glass used in the manufacture of laminated glass by intercalation of the same between two glass sheets that are facing each other, characterized in that it comprises a section profile comprising a continuous of arcs having two or more different radios.

3. - A method of producing an intermediate film for laminated glass according to claims 1 or 2, used in the manufacture of laminated glass, characterized in that it comprises feeding a starting composition for the intermediate film to a production equipment having an extruder , an extrusion die, a first cooling pressure roll and a second cooling pressure roll, wherein both cooling pressure rolls have the distances or separations controlled according to the sectional profile of the intermediate film to be produced .

4. - The production method of an intermediate film for laminated glass according to claim 3, characterized in that different pressures are applied to the axial ends of the first and second cooling pressure rollers to cause the deflection of the rollers and thus reduce the respective separations in the manner of a curve in the axial direction.

5. - A laminated glass characterized in that it comprises the intermediate film for laminated glass according to claim 1 or 2.

6. - A roll of intermediate film for laminated glass that increases in thickness of the film from one edge to the other edge of the axial direction, characterized in that it comprises winding two continuous strips of an intermediate film in superimposition or overlapping one on the other with its edge of a strip that is thin in thickness that is aligned with its edge of the other strip that is greater in thickness.

7. - A method for the production of an intermediate film roll for laminated glass that increases in thickness of the film from one edge to the other edge of the axial direction, characterized in that it comprises winding two continuous strips of an intermediate film in superimposition or overlap one on the other with its edge of a strip that is thin in thickness that is aligned with its edge of the other strip that is greater in thickness.