Method for making textured multilayer optical films

• US 20010011779A1
• Filed: 03/15/2001
• Published: 08/09/2001
• Est. Priority Date: 01/13/1998
• Status: Active Grant

• Current Assignee: 3M Innovative Properties Company (3M Company)
• Original Assignee: 3M Innovative Properties Company (3M Company)
• Inventors: Stover, Carl A.
• Granted Patent: US 6,808,658 B2
• Time in Patent Office: Days
• US Class Current: 264/1.7
• CPC Class Codes: B29C 48/08 flexible, e.g. films
• CPC Class Codes: B29C 48/21 the layers being joined at their surfaces
• CPC Class Codes: B29C 48/22 with means connecting the layers, e.g. tie layers or undercuts
• CPC Class Codes: B29C 48/495 Feed-blocks extrusion moulding of multi-component articles B29C48/16
• CPC Class Codes: B29C 48/71 for layer multiplication extrusion of multi-component articles B29C48/16
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree

Abstract

Methods and apparatuses are provided for the manufacture of coextruded polymeric multilayer optical films. The multilayer optical films have an ordered arrangement of layers of two or more materials having particular layer thicknesses and a prescribed layer thickness gradient throughout the multilayer optical stack. The methods and apparatuses described allow improved control over individual layer thicknesses, layer thickness gradients, indices of refraction, interlayer adhesion, and surface characteristics of the optical films. The methods and apparatuses described are useful for making interference polarizers, mirrors, and colored films that are optically effective over diverse portions of the ultraviolet, visible, and infrared spectra.

Claims

1. A method of making a textured multilayer optical film, said method comprising the steps of:

(a) providing at least a first and a second stream of resin;

(b) dividing said first and said second streams into a plurality of layers such that said layers of said first stream is interleaved with said layers of said second stream to yield a composite stream;

(c) passing said composite stream through an extrusion die to form a multilayer web in which each layer is generally parallel to the major surface of adjacent layers;

(d) casting said multilayer web onto a casting roll; and

(e) contacting said multilayer web by a micro-embossing roll to form a cast multilayer film.