Method of making polyester film with a reduced iridescent primer layer

Patent metadata

Field	Value
Publication number	US-9937525-B2
Application number	US-201514795276-A
Country	US
Kind code	B2
Filing date	Jul 9, 2015
Priority date	Aug 2, 2011
Publication date	Apr 10, 2018
Grant date	Apr 10, 2018

Abstract

This invention relates to a highly optically clear, composite film having a predominantly thermoplastic polyester base layer and a primer layer of a polyester and polyurethane blend composition. The base layer preferably has an A/B/C layered structure with a substantially particle-free core layer B of polyester and outer layers A and C of polyester containing nonpolyester, organic and/or inorganic particles. The primer layer is preferably applied to the base layer from solution that is organic solvent-free and is crosslinked using a carbodiimide crosslinking agent. The primer layer and base layer composite can be laminated with a protective layer of primarily acrylic polymer for a solar control film. Various layers of the composite and solar control films can contain effective amounts of functional additives, such as UV light blockers. Polyurethane in the primer, especially in combination with crosslinking by the carbodiimide, provides the acrylic coated polyester base solar control film with notably reduced iridescence and durable adhesion between polyester and acrylic layers in moist and warm service conditions.

First claim

What is claimed is:

1. A method of making an optically clear reduced iridescent composite film comprising the steps of
(A) providing a dispersion comprising inversely synthesized aliphatic polyurethane particles of size in the range of about 1-100 nm and polyester binder particles of a polyester resin having a softening point lower than 100° C. dispersed in an aqueous medium comprising carbodiimide crosslinking agent dissolved in water,
(B) providing a base layer having a thickness in the range of about 1-500 μm comprising a core layer of polyester film and about 0.1 to 2 wt % of a UV light absorber,
(C) depositing a wet coating of the dispersion onto one side of the base layer,
(D) heating the base layer and wet coating effectively to (i) soften the polyester binder, (ii) evaporate substantially all volatile components of the aqueous medium, and (iii) activate the crosslinking agent, thereby creating a solidified primer layer in contact with the one side of the base layer, in which the wet coating on the base layer is present in an amount effective to produce a thickness of the solidified primer layer in the range of about 0.03-0.15 μm,
(E) providing a solution comprising acrylic polymer, a cure initiator, and an amount of organic solvent effective to dissolve the acrylic polymer,
(F) placing a uniformly thick solvent-wet coating of the solution onto a side of the solidified primer layer opposite the base layer, and
(G) heating the solvent-wet coating effectively to evaporate volatile components of the organic solvent,

so that an optically clear reduced iridescent composite film having a protective layer of solidified acrylic polymer in contact with the solidified primer layer is created, and which the optically clear reduced iridescent composite film has reduced iridescence as compared to a composite film prepared as above without the inversely synthesized aliphatic polyurethane particles.

2. The method of claim 1 in which the inversely synthesized aliphatic polyurethane particles are present in the solidified primer layer at a concentration effective to make the optically clear reduced iridescent composite film have a haze value of at most about 4%.

3. The method of claim 1 in which the base layer further comprises a first outer layer about 0.5-7 μm thick and comprising inorganic particles uniformly dispersed in a polyester matrix, in which the first outer layer is in direct contact with a side of the core layer.

4. The method of claim 3 in which the base layer further comprises a second outer layer about 0.5-7 μm thick and optionally comprising inorganic particles uniformly dispersed in a polyester matrix, in which the second outer layer is in direct contact with a side of the core layer opposite the side of the core layer in direct contact with the first outer layer.

5. The method of claim 1 in which the protective layer is effective to make the optically clear reduced iridescent composite film have a haze value of at most about 3%.

Assignees

• Toray Plastics America Inc

Inventors

• Paolilli Tracy
• Fitch John

Classifications

• G02B1/14

  Protective coatings, e.g. hard coatings · CPC title

• C08J7/0427

  with only one layer of a composition containing a polymer binder (with more layers C08J7/042) · CPC title

• B32B2307/40

  having particular optical properties · CPC title

• C08G18/797

  containing carbodiimide and/or uretone-imine groups · CPC title

• B32B27/18

  characterised by the use of special additives · CPC title