Process forming a shaped laminate

• US 5,529,654 A
• Filed: 06/18/1990
• Issued: 06/25/1996
• Est. Priority Date: 06/18/1990
• Status: Expired due to Fees

• Current Assignee: Solutia Incorporated (Eastman Chemical Company)
• Original Assignee: Monsanto Company (Bayer AG)
• Inventors: Kavanagh, Dean L., Simon, Robert H. M.
• Primary Examiner(s): ENGEL, JAMES J
• Application Number:
  US07/539,256
• Time in Patent Office: 2,199 Days
• Field of Search: 156/99, 156/102, 156/103, 156/104, 156/105, 156/106, 156/229, 156/382, 156/285, 264/544
• US Class Current: 156/229
• CPC Class Codes: B29C 51/36 specially adapted for vacuum forming , Manufacture thereof
• CPC Class Codes: B29C 55/023 using multilayered plates or sheets
• CPC Class Codes: B29C 71/02 Thermal after-treatment B29C71/0063 and B29C71/0072 take precedence
• CPC Class Codes: B29K 2029/00 Use of polyvinylalcohols, polyvinylethers, polyvinylaldehydes, polyvinylketones or polyvinylketals or derivatives thereof as moulding material
• CPC Class Codes: B29K 2067/00 Use of polyesters or derivatives thereof, as moulding material
• CPC Class Codes: B32B 17/10009 characterized by the number, the constitution or treatment of glass sheets
• CPC Class Codes: B32B 17/10871 in combination with particular heat treatment
• CPC Class Codes: B32B 17/10889 shaping the sheets, e.g. by using a mould B32B17/10816 takes precedence
• CPC Class Codes: B32B 17/10981 Pre-treatment of the layers
• CPC Class Codes: B60J 1/02 arranged at the vehicle front , e.g. structure of the glazing, mounting of the glazing on windscreen mounted antenna wire H01Q1/1271

Abstract

A process for forming a shaped laminate for use in a safety glazing such as a vehicle window or the like which comprises lightly bonding at least one flexible, transparent, thermoplastic carrier layer having one or more adherent functional performance layers or coatings on its surface to at least one layer of ptasticized polyvinyl butyral to form a premolding composite, stretching the composite to impart compound curvature thereto and form a shaped, shrinkable laminate, subjecting the shaped laminate to elevated temperature while constraining its edges to relieve stresses in the carrier layer, and cooling the shaped laminate while maintaining its edges constrained.

Claims

1. A process for forming a shaped laminate for use in a safety glazing such as a vehicle window or the like which comprises:

a) encapsulating a flexible, transparent, carrier layer of biaxially orientated polyethylene terephthalate having a multilayer solar radiation control or electrically conductive stack on its surface within layers of plasticized polyvinyl butyral to form a premolding composite;

b) clamping a section of the premolding composite along its margins to constrain its edges against movement;

c) heating the premolding composite within the clamped margins to shaping temperature;

d) stretching the heated composite against the surface of a shaping mold to impart compound curvature thereto and form a shaped, shrinkable laminate;

e) heating the shaped, shrinkable laminate to a temperature above the shaping temperature while its edges are constrained to relieve stresses in the laminate developed during step d; and

f) cooling the stress-relieved, shaped laminate while maintaining its edges constrained.

2. The process of claim 1 wherein the temperature of the shaped, shrinkable laminate reached in step e) is about the temperature of the laminate during autoclave forming of the safety glazing.

3. In the preparation of a safety glazing such as a windshield or the like, having compound curvature using a laminate which includes a carrier layer having a functional coating with properties enhancing performance of the safety glazing, a method reducing wrinkling of the carrier layer in the safety glazing comprising the steps of:

a) lightly bonding a transparent, thermoplastic carrier layer having one or more adherent functional performance layers or coatings on its surface to at least one layer of plasticized polyvinyl butyral to form a premolding composite;

b) stretching the composite to impart compound curvature thereto and form a shaped, shrinkable laminate;

c) subjecting the shaped laminate to elevated temperature while constraining its edges against movement to relieve stresses in the carrier layer;

d) cooling the shaped laminate while maintaining its edges constrained;

e) associating the shaped laminate containing the stress-relieved carrier layer with at least one transparent rigid panel of matching shape; and

then

f) subjecting the shaped laminate and rigid panel to elevated temperature and pressure to strongly bond the shaped laminate to at least one rigid panel and form a delamination-resistant safety glazing substantially free of wrinkles in the carrier layer.

4. The process of claim 3 wherein step e) includes applying the shaped laminate against the surface of the at least one rigid panel while deairing the interface between the shaped laminate and said rigid panel.

5. The process of claim 3 or 4 wherein the shaped laminate in step e) is interposed between two rigid panels.

6. The process of claim 5 wherein the rigid panels are glass.

7. The process of claim 6 wherein the temperature in step f) does not exceed the temperature of the laminate reached in step c).

8. A process for forming a shaped laminate for use in a safety glazing such as a vehicle window or the like which comprises:

a) joining at least one flexible, transparent, thermoplastic carrier layer having one or more adherent functional performance layers or coatings on its surface with at least one layer of plasticized polyvinyl butyral to form a premolding composite;

b) clamping a planar section of the premolding composite along its margins adjacent a functioning heater to constrain its edges against movement and to increase the temperature within the clamped margins of at least the carrier layer to shaping temperature;

c) drawing the composite including the heated carrier layer within the clamped margins against the surface of an adjacent mold having compound curvature to form a shaped laminate including the carrier layer having matching compound curvature and rendered shrinkable from induced stresses developed during said drawing;

d) holding the shaped laminate which includes the shrinkable carrier layer against the mold surface under the influence of the functioning heater while the margins remain clamped to raise the temperature of the shrinkable carrier layer above the shaping temperature to relieve said stresses; and

e) cooling the shaped laminate containing the stress relieved carrier layer while holding said shaped laminate in surface contact with the mold surface.

9. The process of claim 8 wherein the carrier layer in step a) is biaxially stretched polyethylene terephthalate film.

10. The process of claim 9 wherein the polyethylene terephthalate film is heat set before carrying out step a).

11. The process of claim 8 or 9 wherein the one or more adherent performance layers or coatings comprise a multilayer solar radiation control or electrically heatable stack.

12. The process of any of claims 10, 3 or 8 wherein the thickness of the carrier layer is about 0.0005 to 0.008 inch.