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Thermoforming system for masked polymers

a technology of thermoforming system and masking polymer, which is applied in the direction of application, chain saw, manufacturing tools, etc., can solve the problems of difficult removal of adhesive bonding agent difficult application of masking, and difficult removal of adhesive bonding agent completely from the substrate surface, etc., to achieve energy saving, reduce thermoforming temperature, and superior optical clarity

Inactive Publication Date: 2005-03-10
PERCYS PERFORMANCE PLASTICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

"The present invention is a thermoforming system for masked polymer substrates that is energy efficient, minimizes thermoforming temperatures, and produces a product with superior optical clarity. The system uses a temperature-resistant, non-stick coating applied to a sheet of thermoformable polymer substrate material. The coated sheet is positioned on a flexible platen over a mold and heated until the polymer reaches a thermoforming temperature and softens. The platen is then lowered to stretch over and cover the mold. The heat is withdrawn and a second platen is lowered over the sheet to urge it into conformance with the mold. The non-stick coating prevents adhesion of the masked polymer sheet to the platen surfaces. The system can be used with existing polymer film masking and rapidly cures to form a non-stick surface."

Problems solved by technology

Thermoformable polymers are not abrasion resistant.
Such masking is difficult to apply and an adhesive composition must be employed to bond the paper to the polymer sheet.
Adhesive bonding agents are incompatible with many polymer compositions and may chemically interact with the polymer, altering the surface of the sheet, for example, with pitting or blistering.
Adhesive bonding agents may be also be difficult to remove completely from the substrate surface when the masking is removed.
Adhesively bonded protective masking is not suitable for use during thermoforming and must be removed prior to the application of heat to the polymer substrate in order to avoid melting the adhesive into the substrate.
Once the protective masking is removed, the surfaces of the polymer sheet are exposed to damage from abrasion and scratching inflicted by the hard surfaces of the mold during thermoforming.
In addition, static electricity may cause the unmasked polymer surfaces to become contaminated with dust and grit during thermoforming and incidental handling.

Method used

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  • Thermoforming system for masked polymers
  • Thermoforming system for masked polymers
  • Thermoforming system for masked polymers

Examples

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Effect test

example 1

[0035] A polycarbonate sheet was subject to a thermoforming process according to the method of the invention to produce a curved automotive windshield free of surface marking, as follows:

[0036] Coating:

[0037] A sheet 12 of 9030 grade polished Lexan® polycarbonate produced by General Electric Structural Products, Mt. Vernon, Ind. was employed as a substrate. Both surfaces of the polycarbonate sheet were factory laminated by General Electric with a 0.002 inch thick protective laminate 14 of sign grade adhesive-free polyethylene. Black Pitt-Therm 97-724, a heat resistant silicone produced by PPG Architectural Finishes, was thinned 5.6:1 by weight with Varnish Makers and Painters Naptha (petroleum spirits) to produce a coating mixture. A 0.002 inch thick coating 16 was applied to both laminated surfaces of the polycarbonate sheet by spraying.

[0038] Thermoforming Equipment:

[0039] A modified model 406XX PVI Thermoformer, produced by Plasti-Vac, Inc. of Charlotte N.C. was used. The mac...

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Abstract

In a thermoforming system for masked polymer substrate sheets, a temperature resistant, non-stick coating is applied to a sheet of a polymer substrate material. The coated sheet is positioned on a flexible platen positioned over a mold having a predetermined shape. Heat is applied until the polymer reaches a thermoforming temperature and softens, whereupon the platen is lowered to stretch over and cover the mold. When the sheet begins to conform to the mold, the heat is withdrawn and a second platen is lowered over the sheet to urge it into conformance with the mold. The temperature resistant coating can be applied over an existing polymer film masking, and rapidly cures to form a non-stick surface which prevents adhesion of the masked polymer sheet to the platen surfaces.

Description

BACKGROUND OF INVENTION [0001] 1. Field of the Invention [0002] The present invention is concerned with a system for thermoforming masked polymer substrates. [0003] 2. Description of the Related Art [0004] Transparent and selectively transparent thermoformable polymeric synthetic resin compositions are employed to form a variety of products such as lenses, windows, housings and a wide-variety of containers and coverings. These polymer compositions are particularly well-suited for automotive use because they provide glass-like optical clarity yet are substantially lighter in weight and offer greater crash safety. High polymer thermoplastic compositions such as polycarbonate, present a superior substrate for molded windshields and windows for vehicles of all types, for example, racing cars, motorcycles, all terrain vehicles, automobiles, heavy equipment, boats and aircraft, as well as for skylights and windows used in conventional housing and mobile homes. [0005] The clear polymer sub...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): B29C51/02B29C51/08B29C51/14B29C51/28
CPCB29C51/02B29C51/28B29C51/14B29C51/08Y10T428/31551Y10T428/31935Y10T428/31511Y10T428/31786Y10T428/31544Y10T428/31663
Inventor PERCIVAL, JEFFREY D.
Owner PERCYS PERFORMANCE PLASTICS
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