Plastic glass

• US 20030001301A1
• Filed: 07/02/2001
• Published: 01/02/2003
• Est. Priority Date: 07/02/2001
• Status: Active Grant

• Current Assignee: Schefenacker Vision Systems USA Incorporated (The Sumi Motherson Group)
• Original Assignee: Schefenacker Vision Systems USA Incorporated (The Sumi Motherson Group)
• Inventors: Settier, Roger, Duroux, Bernard
• Granted Patent: US 6,638,454 B2
• Time in Patent Office: Days
• US Class Current: 264/40.5
• CPC Class Codes: B29C 2045/0079 applying a coating or covering
• CPC Class Codes: B29C 2045/5635 Mould integrated compression drive means
• CPC Class Codes: B29C 2045/567 Expelling resin through the gate
• CPC Class Codes: B29C 2945/76006 Pressure
• CPC Class Codes: B29C 2945/76257 cavity
• CPC Class Codes: B29C 2945/76391 Mould clamping, compression of the cavity
• CPC Class Codes: B29C 2945/76575 end position
• CPC Class Codes: B29C 2945/76732 Mould
• CPC Class Codes: B29C 2945/76869 Mould clamping, compression of the cavity
• CPC Class Codes: B29C 45/561 Injection-compression moulding
• CPC Class Codes: B29C 45/77 of velocity or pressure of moulding material
• CPC Class Codes: B29D 11/00596 Mirrors
• CPC Class Codes: B29K 2995/0026 Transparent
• CPC Class Codes: B29L 2011/0058 Mirrors
• CPC Class Codes: B60R 1/082 using a single wide field mirror or an association of rigidly connected mirrors

Abstract

A method of manufacture of high optical quality transparent plastic for use as a mirror or glass substitute.

Claims

1. A process for producing plastic materials suitable for use as a vehicle mirror comprising:

(a) providing an injection mold machine having a cavity therein for forming of a transparent plastic article simulating glass, said mold including a pressure sensing and regulating apparatus;

(b) closing the mold and injecting a clear plastic material into the mold using a portion of the mold to pressurize the mold material back into the injection port; and

(c) substantially maintaining the mold at a predetermined pressure wherein internal stress in said plastic material is substantially reduced for optimizing optical properties of said plastic material to be substantially similar to glass for mirrors.

2. The process of claim 1 wherein a first portion of said mold includes a mold cavity;

and a second portion is adapted for pressurizing said cavity after molten plastic is injected therein.

3. The process of claim 2 wherein the second portion includes a piston for forcing molten plastic back through the injection port.

4. The process of claim 3 wherein said back pressure from said second piston is held on the chamber for a period of time of from about 0.01 to about 60 seconds.

5. The process of claim 3 wherein said plastic is allowed to cool under while said pressure is applied for a predetermined time.

6. The process of claim 5 wherein a second piston is used for controlling pressure.

7. The process of claim 5 wherein the predetermined time is from about 10 to about 50 seconds.

8. The process of claim 1 wherein the pressure is maintained in the cavity at greater than about 900 barr.

9. The process of claim 1 wherein the pressure is maintained in the cavity from about 1000 to about 1800 barr.

10. The process of claim 1 wherein the pressure is maintained in the cavity at from about 1000 to about 1200 barr.

11. The process of claim 9 wherein the temperature is maintained at about 80°

C.-120°

C. for a time period of from 18 to 25 seconds at pressure.

13. The process of claim 12 wherein a first portion of said mold includes a mold cavity;

and a second portion is adapted for pressurizing said cavity after molten plastic is injected therein.

14. The process of claim 13 wherein the second portion includes a second pressure adjustment control piston operatively connected to said mold cavity piston for forcing molten plastic back through the injection port.

15. The process of claim 12 wherein said pressure is maintained in the mold for a time of from about 0.01 to about 60 seconds.

16. The process of claim 15 wherein said plastic is allowed to cool under while said pressure is applied for a predetermined time.

17. The process of claim 12 wherein a second piston is used for controlling pressure.

18. The process of claim 16 wherein the predetermined time is from about 10 to about 50 seconds.

19. The process of claim 12 wherein the pressure is maintained in the cavity at from about 1000 to about 1900 barr.

20. The process of claim 12 wherein the pressure is maintained in the cavity at from about 1000 to about 1200 barr.

21. The process of claim 12 wherein the temperature is maintained at about 80°

C.-120°

C. for a time period of from 18 to 25 seconds at pressure.

22. The process of claim 12 wherein a reflective material is formed on a surface of said transparent plastic article for forming a mirror.

12. A process for producing plastic materials suitable for use as a vehicle mirror comprising:

(a) providing an injection mold machine having a cavity therein for forming of a transparent plastic article simulating glass, said mold including a pressure sensing and regulating apparatus and control for monitoring and controlling injection molding parameters of pressure and volume;

(b) closing the mold and injecting an initial volume of a clear plastic material in to the mold using a portion of the mold to force from about 20% to about 60% of the mold material back into the injection port; and

(c) substantially maintaining the mold at a predetermined pressure of greater than about 900 barr for reducing shrinkage and internal stress in the plastic material for optimizing optical properties of said plastic material to be substantially similar to glass for mirrors.