Cold-formed laminates
The principles and embodiments of the present disclosure relate generally to complexly curved laminates made from a complexly curved substrate and a flat substrate, such as automotive window glazings, and methods of cold forming complexly-curved glass products from a curved substrate and a flat substrate. In one or more embodiments, the laminate includes first complexly-curved glass substrate with a first surface and a second surface opposite the first surface, a second complexly-curved glass substrate with a third surface and a fourth surface opposite the third surface with a thickness therebetween; and a polymer interlayer affixed to the second convex surface and third surface, wherein the third surface and fourth surface have compressive stress values respectively that differ such that the fourth surface has as compressive stress value that is greater than the compressive stress value of the third surface.
1. A laminate comprising:
a first complexly-curved glass substrate comprising a first surface, a second surface opposite the first surface, and a first thickness therebetween;
a second complexly-curved glass substrate comprising a third surface, a fourth surface opposite the third surface, and a second thickness therebetween; and
a polymer interlayer affixed to the second surface and the third surface, wherein:
the laminate has a thickness in a range from 1.8 mm to 5.85 mm,
the second substrate is formed of an aluminosilicate glass composition,
the first complexly-curved glass substrate is hot-formed and curved along at least a first axis with a first radius of curvature of 5 m or less and a second axis with a second radius of curvature of 5 m or less,
the second complexly-curved glass substrate is cold-formed against the first complexly-curved glass substrate via the polymer interlayer at a temperature that is 200° or more below a softening point of the second complexly-curved glass substrate such that a peripheral portion of the second complexly-curved substrate exerts a compressive force against the polymer interlayer and a central portion of the second complexly-curved substrate exerts a tensile force against the polymer interlayer, and
one of:
the second complexly-curved glass substrate is chemically strengthened and comprises a surface compressive stress of 300 MPa or greater, and
the second complexly-curved glass substrate is thermally strengthened and comprises a fictive temperature of at least 500° C.
2. The laminate of claim 1 , wherein the first complexly-curved glass substrate comprises a soda lime glass or an alkali-containing borosilicate glass.
3. The laminate of claim 1 , wherein the polymer interlayer comprises a thickness that is greater than or equal to 0.3 mm and less than or equal to 2.0 mm, wherein the polymer interlayer comprises polyvinyl butyral, ethylene-vinyl acetate, an ionomer, a polyvinyl chloride copolymer, or a thermoplastic polyurethane.
4. The laminate of claim 1 , further comprising a uniform distance between the second surface and the third surface.
5. The laminate of claim 1 , wherein the laminate comprises a radii of curvature in a range from about 2 meters to about 2.5 meters along a minor axis of the laminate and a radius of curvature in a range from about 4 meters to about 5 meters along a major axis of the laminate.
6. The laminate of claim 1 , wherein the first thickness is more than two times the second thickness.
7. The laminate of claim 1 , wherein the second complexly-curved glass substrate is chemically strengthened.
8. The laminate of claim 1 , wherein the laminate comprises a windshield, a backlight, a sunroof, a fix-mounted roof panel, or a sidelight.
9. The laminate of claim 1 , wherein the second complexly-curved glass substrate is fusion-formed and comprises an as-formed Ra surface roughness that is less than 0.3 nm.
10. The laminate of claim 9 , wherein the first complexly-curved glass substrate is float-formed and comprises an as-formed Ra surface roughness that is greater than or equal to 0.6 nm and less than or equal to 0.7 nm.
11. The laminate of claim 1 , wherein the first complexly-curved glass substrate is thermally strengthened and comprises a fictive temperature of at least 500° C.
12. The laminate of claim 1 , wherein a portion of the laminate containing the central portion does not exhibit visible optical distortion, wherein optical distortion is evaluated according to ASTM Standard C1036-06.
13. The laminate of claim 12 , wherein the peripheral portion exhibits detectable levels of optical distortion, but the optical distortion is covered by a decoration band disposed on the peripheral portion.
14. The laminate of claim 12 , wherein the first thickness is greater than or equal to 1.6 mm and less than or equal to 3.85 mm.
15. The laminate of claim 14 , wherein the second thickness is greater than or equal to 0.5 mm and less than or equal to 1.4 mm.
16. A laminate comprising:
a first complexly-curved glass substrate comprising a first surface, a second surface opposite the first surface, and a first thickness therebetween;
a second complexly-curved glass substrate comprising a third surface, a fourth surface opposite the third surface, and a second thickness therebetween; and
a polymer interlayer affixed to the second surface and the third surface, wherein:
the laminate has a thickness in a range from 1.8 mm to 5.85 mm,
the second substrate is formed of an aluminosilicate glass composition,
the first complexly-curved glass substrate is hot-formed and curved along at least a first axis with a first radius of curvature of 5 m or less and a second axis with a second radius of curvature of 5 m or less,
the second complexly-curved glass substrate is cold-formed against the first complexly-curved glass substrate via the polymer interlayer at a temperature that is 200° or more below a softening point of the second complexly-curved glass substrate such that a peripheral portion of the second complexly-curved substrate exerts a compressive force against the polymer interlayer and a central portion of the second complexly-curved substrate exerts a tensile force against the polymer interlayer, and
a portion of the laminate containing the central portion does not exhibit optical distortion that is visible to the naked eye as a result of cold-forming, wherein optical distortion is evaluated according to ASTM Standard C1036-06.
17. The laminate of claim 16 , wherein:
the first thickness is greater than or equal to 1.6 mm and less than or equal to 3.85 mm, and
the second thickness is greater than or equal to 0.5 mm and less than or equal to 1.4 mm.
18. The laminate of claim 16 , wherein the peripheral portion exhibits detectable levels of optical distortion, but the optical distortion is covered by a decoration band disposed on the peripheral portion.
19. The laminate of claim 16 , wherein one of:
the second complexly-curved glass substrate is chemically strengthened and comprises a surface compressive stress of 300 MPa or greater, and
the second complexly-curved glass substrate is thermally strengthened and comprises a fictive temperature of at least 500° C.
20. The laminate of claim 19 , wherein the first complexly-curved glass substrate comprises a soda lime glass or an alkali-containing borosilicate glass.