WO2008058115A2

WO2008058115A2 - Iridescent films with multiple reflection peaks

Info

Publication number: WO2008058115A2
Application number: PCT/US2007/083749
Authority: WO
Inventors: Steven Jones; Marc Giammatteo
Original assignee: Basf Corporation
Priority date: 2006-11-08
Filing date: 2007-11-06
Publication date: 2008-05-15
Also published as: KR20090083447A; JP2010509646A; EP2084020A2; WO2008058115A3; MX2009004924A; CA2669808A1; CN101553371A

Abstract

The invention is directed to laminated multilayered films which generate unique color via two distinct reflection peaks. Each multilayered iridescent film has a dominant wave length reflective band which is different from the other multilayered film laminated thereto. The present iridescent film may be used in flexible and rigid decorative packaging.

Description

IRIDESCENT FILMS WITH MULTIPLE REFLECTION PEAKS

FIELD

The present invention is directed to iridescent films with multiple reflection peaks having unique color and effects.

BACKGROUND

In general, this invention is directed to multilayer coextruded light- reflecting films which have a narrow reflection band due to light interference. When the reflection band occurs within the range of visible wavelength, the film is iridescent. Similarly, when the reflection band falls outside the range of visible wavelength, the film is either ultraviolet or infrared reflecting. Such multilayer films and methods by which they can be produced are known in the art. They are described, for instance, in U.S. Patents 3,565,985; 3,759,657; 3,773,882; and 3,801 ,429 and other patents.

The multilayer films are composed of a plurality of generally parallel layers of transparent thermoplastic resinous material in which the contiguous adjacent layers are of diverse resinous material whose index of refraction differs by at least about 0.03. The film contains at least 10 layers and more usually at least 35 layers and, preferably, at least about 70 layers.

The individual layers of the film are very thin, usually in the range of about 30 to 500 nm, preferably about 50-400 nm, which causes constructive interference in light waves reflected from the many interfaces. Depending on the layer thickness and the refractive index of the polymers, one dominant wavelength band is reflected and the remaining light is transmitted through the film. The reflected wavelength is proportional to the sum of the optical thickness of a pair of layers.

The quantity of the reflected light (reflectance) and the color intensity depend on the difference between the two refractive indices, on the ratio of optical thicknesses of the layers, on the number of layers and on the uniformity of the thickness. If the refractive indices are the same, there is no reflection at all from the interfaces between the layers. In multilayer iridescent films, the refractive indices of contiguous adjacent layers differ by at least 0.03 and preferably by at least 0.06 or more. For first order reflections, reflectance is highest when the optical thicknesses of the layers are equal, although suitably high reflectances can be achieved when the ratio of the two optical thicknesses falls between 5:95 and 95:5. Distinct color reflections are obtained with as few as 10 layers. However, for maximum color intensity it is desired to have between 35 and 1 ,000 or even more layers. High color intensity is associated with a reflection band which is relatively narrow and which has high reflectance at its peak. It should be recognized that although the term "color intensity" has been used here for convenience, the same considerations apply to the invisible reflection in the ultraviolet and infrared ranges.

The multilayer films can be made by a chill-roll casting technique using a conventional single manifold flat film die in combination with a feedblock which collects the melts from each of two or more extruders and arranges them into the desired layer pattern. The number of layers and their thickness distribution can be changed by inserting a different feedblock module. Usually, the outermost layer or layers on each side of the sheet are thicker than the other layers. This thicker skin may consist of one of the components which makes up the optical core; may be a different polymer which is utilized to impart desirable mechanical, heat sealing, or other properties; or may be a combination of these.

Some recent developments in the iridescent film are described in U.S. Patents Nos. Re. 31 ,780; 4,937,134; and 5,089,318. U.S. Patent Re. 31 ,780 describes using a thermoplastic terephthalate polyester or copolyester resin as the high refractive index component of the system. Formation of elastomeric interference films is described in U.S. Patent No. 4,937,134 in which all of the resinous materials are certain thermoplastic polyurethanes, polyester block amides or flexible copolyesters. U.S. Patent No. 5,089,318 discloses improved multilayer light-reflecting transparent thermoplastic resinous film of at least 10 generally parallel layers in which the contiguous adjacent layers are of diverse transparent thermoplastic resinous material differing in refractive index by at least about 0.03 and at least one of the resinous materials being an engineering thermoplastic elastomer resin. Conventional multi-nanolayered films designed for optical and decorative purposes possess uninterrupted layering of the color-generating polymer pairs. This design maximizes the transparency of the structure to facilitate constructive interference of incident light throughout the optical core.

For certain applications, it is desirable to maximize the reflection of the targeted wavelengths and minimize any transmission effects. This can be demonstrated with a lamination of a typical iridescent film onto a black substrate, whereupon the reflection colors are maximized. The effect, however, is limited to one surface. To attain identical effects on both surfaces requires another film being laminated to that surface, increasing the overall cost and complexity for this effect.

Prior art laminated films has also exaggerated poor color uniformity across the web and as a result poorly conceived colors have been produced. Other prior art used higher order films to create multiple refection peaks that are generally weaker than the first order peaks and are very difficult to control.

SUMMARY

The present invention is directed to laminated films that generate unique color via two distinct reflection peaks. These multiple peak iridescent films travel through the L*a*b* color space in unique ways, generating new and interesting colors. As the short wavelength reflection peak shifts blue, violet, and then clear (ultraviolet), a typical iridescent film will simply loose all color. With multiple reflection peaks the longer wavelength peak will continue to generate color as the short wavelength reflection peak disappears from view. By tailoring the reflection wavelength, combination colors such as magenta, gold, turquoise, etc. can now be generated with a single standard feed ring. DETAILED DESCRIPTION

The phrase "generally parallel layers" as used herein means that adjacent layers remain generally in the x-y plane and have minimal or no z direction shift. Multilayer coextruded iridescent film per se is known in the art. It is described in U.S. Patent Re 31 ,780 to Cooper, Shetty and Pinksy and U.S. Patents 5,089,318 and 5,451 ,449, both to Shetty and Cooper, all of which are incorporated herein by reference, and in other patents. The iridescent film is, as there described, a transparent thermoplastic resinous coextruded laminated film of at least 10 very thin layers, preferably at least about 35 layers and more preferably at least about 70 layers, each of which is usually in the range of about 30-500 nm and more preferably about 50-400 nm, with the layers being generally parallel and the contiguous adjacent layers being of different transparent thermoplastic resinous materials differing in refractive index by at least about 0.03, and more preferably, at least about 0.06. The outermost layers of the film constituting a skin, when present, are each at least about 5% of the total thickness of the film.

Any of the thermoplastic resinous material used to prepare iridescent film heretofore can be used in the present invention as long as the individual materials have the characteristics set forth above and likewise, the combination of selected resinous materials has the characteristics detailed above. Useful polymers for the film layers include polyesters, polyacrylates, polyethylene vinyl acetate, polyolefins, and polystryenes. For example, polyesters include polyethylene terephthalate, polybutylene terephthalate, glycol modified polyethylene terephthalate made from ethylene glycol, and cyclohexamedimethanol characterized by a refractive index of about 1.55 to 1.61 , and polyethylene naphthalate as disclosed in commonly assigned US Patent 6,475,608, incorporated herein by reference. A useful polyacrylate includes polymethyl methacrylate. Non-limiting examples of useful films include alternating layers of polybutylene terephthalate (hereinafter "PBT") and polymethyl methacrylate (hereinafter "PMMA"); alternating layers of polyethylene terephthalate (PET) and polymethyl methacrylate; alternating layers of polystyrene and ethylene vinyl acetate (hereinafter "EVA"); alternating layers of polyethylene naphthalate and polymethyl methacrylate; alternating layers of polyethylene terephthalate and ethylene methyl acrylate (hereinafter "EMA"); and alternating layers of polyethylene naphthalate and polymethyl methacrylate. The layers may be colored or tinted as taught by commonly assigned US Patent 5,451 ,449. Table 1 below sets forth additional polymers which can be used to form the films of this invention.

TABLE 1

Polymer name Approximate

Refractive

Index

Poly(tetrafluoroethylene-co-hexafluoropropylene) 1.338

Poly(pentadecafluorooctyl acrylate) 1.339

Poly(tetrafluoro-3-(heptafluoropropoxy)propyI 1.346 acrylate)

Poly(tetrafluoro-3-(pentafluoroethoxy)propyl 1.348 acrylate)

Poly(tetrafluoroethylene) 1.35 (-1.38)

Poly(undecafluorohexyl acrylate) 1.356

Poly(nonafluoropentyl acrylate) 1.360

Poly(tetrafluoro-3-(trifluoromethoxy)propyl 1.360 acrylate)

Poly(pentafluorovinyl propionate) 1.364

Poly(heptafluorobutyl acrylate) 1.367

Poly(trifluorovinyl acetate) 1.375

Poly(octafluoropentyl acrylate) 1.380

Poly(pentafluoropropyl acrylate) 1.385

Poly(2-(heptafluorobutoxy)ethyl acrylate) 1.390

Poly(2,2,3,4,4,4-hexafluorobutyl acrylate) 1.392

Poly (trif I uo roethy I acrylate) 1.407

Poly(2-(1 ,1 ,2,2-tetrafluoroethoxy)ethyl acrylate) 1.412

Poly(trifluoroisopropyl methacrylate) 1.4177

Poly(2,2,2-trifluoro-1 -methylethyl methacrylate) 1.4185

Poly(2-(trifluoroethyoxy)ethyl acrylate) 1.419

Poly(trifluorochloroethylene) 1.42-1.43

Poly(vinylidene fluoride) 1.42

Poly(dimethylsilylene(poly(dimethyl siloxane)) 1.43

Poly(trifluoroethyl methacrylate) 1.437

Poly(oxypropylene) 1.4495

Polyvinyl isobutyl ether) 1.4507

Polyvinyl ethyl ether) 1.4540

Poly(oxyethylene) 1.4563

Polyvinyl butyl ether) 1.4563

Polyvinyl pentyl ether) 1.4581

Polyvinyl hexy ether) 1.4591

Poly(4-methyl-1 -pentene) 1.459-1.465

Cellulose acetate butyrate 1.46-1.49

Poly(4-fluoro-2-trifluoromethylstyrene) 1.46

Polyvinyl octyl ether) 1.4613

Polyvinyl 2-ethylhexyl ether) 1.4626

Polyvinyl decyl ether) 1.4628

Poly(2-methoxyethyl acrylate) 1.463 Poly(butyl acrylate) 1.4631

Poly(butyl acrylate) 1.466

Poly(tert-butyl methacrylate) 1.4638

Polyvinyl dodecyl ether) 1.4640

Poly(3-ethoxypropyl acrylate) 1.465

Poly(oxycarbonyl tetramethylene) 1.465

Polyvinyl propionate) 1.4665

Polyvinyl acetate) 1.4665

Polyvinyl methyl ether) 1.467

Poly(ethyl acrylate) 1.4685

Poly(ethylene-co-vinyl acetate) 1.47-1.50 (30%-20% vinyl acetate)

Cellulose propionate 1.47-1.49

Cellulose acetate propionate 1.47

Benzyl cellulose 1.47-1.58

Phenol-formaldehyde resins 1.47-1.70

Cellulose triacetate 1.47-1.48

Polyvinyl methyl ether) (isotactic) 1.4700

Poly(3-methoxypropyl acrylate) 1.471

Poly(2-ethoxyethyl acrylate) 1.471

Poly(methyl acrylate) 1.472-1.480

Poly(isopropyl methacrylate) 1.4728

PoIy(I -decene) 1.4730 Poly(propylene) (atactic, density 0.8575 g/cm.sup.3) 1.4735

Polyvinyl sec-butyl ether) (isotactic) 1.4740

Poly(dodecyl methacrylate) 1.4740

Poly(oxyethyleneoxysuccinoyl) 1.4744 (poly(ethylene succinate))

Poly(teradecyl methacrylate) 1.4746

Poly(ethylene-co-propylene) (EPR-rubber) 1.4748-1.48

Poly(hexadecyl methacrylate) 1.4750

Polyvinyl formate) 1.4757

Poly(2-fluoroethyl methacrylate) 1.4768

Poly(isobutyl methacrylate) 1.477

Ethyl cellulose 1.479

Polyvinyl acetal) 1.48-1.50

Cellulose acetate 1.48-1.50

Cellulose tripropionate 1.48-1.49

Poly(oxymethylene) 1.48

Polyvinyl butyral) 1.48-1.49

Poly(n-hexyl methacrylate) 1.4813

Poly(n-butyl methacrylate) 1.483

Poly(ethylidene dimethacrylate) 1.4831

Poly(2-ethoxyethyl methacrylate) 1.4833

Poly(oxyethyleneoxymaleoyl) 1.4840 (poly(ethylene maleate))

Poly(n-propyl methacrylate) 1.484

Poly(3,3,5-trimethylcyclohexyl methacrylate) 1.485

Poly(ethyl methacrylate) 1.485 Poly (2-nitro-2-methylpropyl 1.4868 methacrylate) 1.4889 Poly(triethylcarbinyl methacrylate)

PoIy(1 , 1 -diethyipropyl methacrylate) 1.4889

Poly(methyl methacrylate) 1.4893 Poly(2-decyl-1 ,3-butadiene) 1.4899

Polyvinyl alcohol) 1.49-1.53

Poly(ethyl glycolate methacrylate) 1.4903

Poly(3-methylcyclohexyl methacrylate) 1.4947

Poly(cyclohexyl . alpha. -ethoxyacrylate) 1.4969 Methyl cellulose(low viscosity) 1.497

Poly(4-methylcyclohexyl methacrylate) 1.4975

Poly(decamethylene glycol dimethacrylate) 1.4990

Poly(urethanes) 1.5-1.6

PoIy(1 , 2-butadiene) 1.5000 Polyvinyl formal) 1.50

Poly(2-bromo-4-trifluoromethylstyrene) 1.5

Cellulose nitrate 1.50-1.514

Poly(sec-butyl .alpha.-chloroacrylate) 1.500

Poly(2-beptyl-1 ,3-butadiene) 1.5000 Polyjethyl .alpha.-chloroacrylate) 1.502

Poly(2-isopropyl-1 ,3-butadiene) 1.5028

Poly(2-methylcyclohexyl methacrylate) 1.5028

Poly(propylene) (density 0.9075 g/cm.sup.3) 1.5030

Poly(isobutene) 1.505-1.51 Poly(bornyl methacrylate) 1.5059

Poly(2-tert-butyl-1 ,3-butadiene) 1.5060

Poly(ethylene glycol dimethacrylate) 1.5063

Poly(cyclohexyl methacrylate) 1.5066

Poly(cyclohexanediol-1 ,4-dimethacrylate) 1.5067 Butyl rubber (unvulcanized) 1.508

Poly(tetrahydrofurfuryl methacrylate) 1.5096

Gutta percha (5) 1.509

Poly(ethylene) ionomer 1.51 poly(oxyethylene) (high molecular weight) 1.51-1.54 Poly(ethylene) (density 0.914 g/cm.sup.3) 1.51

(density 0.94-0.945 g/cm.sup.3) 1.52-1.53

(density 0.965 g/cm.sup.3) 1.545

PoIy(I -methylcyclohexyl methacrylate) 1.5111

Poly(2-hydroxyethyl methacrylate) 1.5119 Polyvinyl chloroacetate) 1.512 Poly(butene) (isotactic) 1.5125

Polyvinyl methacrylate) 1.5129

Poly(N-butyl-methacrylamide) 1.5135

Gutha percha (.alpha.) 1.514 Terpene resin 1.515

PoIy(1 ,3-butadiene) 1.5154

Shellac 1.51-1.53

Poly(methyl .alpha.-chloroacrylate) 1.517

Poly(2-chloroethyl methacrylate) 1.517 Poly(2-diethylaminoethyl methacrylate) 1.5174

Poly(2-chlorocyclohexyl methacrylate) 1.5179

PoIy(1 ,3-butadiene) (35% cis; 56% trans; 7% 1.5180 1 ,2-content)

Natural rubber 1.519-1.52 Poly(allyl methacrylate) 1.5196

Polyvinyl chloride) + 40% dioctyl phthalate 1.52

Poly(acrylonitrile) 1.52

1.5187

Poly(methacrylonitrile) 1.52 PoIy(1 , 3-butadiene) (high cis-type) 1.52

Poly(butadiene-co-acrylonitrile) 1.52

Poly(methyl isopropenyl icetone) 1.5200

Poly(isoprene) 1.521

Poly(ester) resin, rigid (ca, 50% styrene) 1.523-1.54 Poly(N-(2-methoxyethyl)methacrylamide) 1.5246

Poly(2,3-dimethylbutadiene) (methyl rubber) 1.525

Polyvinyl chloride-co-vinyl acetate) (95/5-90/10) 1.525-1.536

Poly(acrylic acid) 1.527

PoIy(1 ,3-dichioropropyl methacrylate) 1.5270 Poly(2-chioro-1-(chloromethyl)ethyl methacrylate) 1.5270

Poly(acrolein) 1.529

PoIy(I -vinyl-2-pyrrolidone) 1.53

Hydrochlorinated rubber 1.53.-1.55

Nylon 6: Nylon 6,6: Nylon 6, 10 (moulding) 1.53 (Nylon-6-fiber: 1.515 transverse,

1.565 in fiber direction)

Poly(butadiene-co-styrene) (ca, 30% styrene) 1.53 black copolymer

Ethylene/norbornene copolymer 1.53 Poly(cyclohexyl .alpha.-chloroacrylate) 1.532

Poly(2-chloroethyl .alpha.-chloroacrylate) 1.533

Poly(butadiene-co-styrene) (ca, 75/25) 1.535

Poly(2-aminoethyl methacrylate) 1.537

Polyjfurfuryl methacrylate) 1.5381 Proteins 1.539-1.541 Poly(butylmercaptyl methacrylate) 1.5390

PoIy(I -phenyl-n-amyl methacrylate) 1.5396

Poly(N-methyl-methacrylamide) 1.5398

Cellulose 1.54 Polyvinyl chloride) 1.54-1.55

Urea formaldehyde resin 1.54-1.56

Poly(sec-butyl . alpha. -bromoacrylate) 1.542

Poly(cyclohexyl .alpha.-bromoacrylate) 1.542

Poly(2-bromoethyl methacrylate) 1.5426 Poly(dihydroabietic acid) 1.544

Poly(abietic acid) 1.546

Poly(ethylmercaptyl methacrylate) 1.547

Poly(N-allyi methacrylamide) 1.5476

PoIy(I -phenylethyl methacrylate) 1.5487 Poly(vinylfuran) 1.55

Poly(2 -vinyltetrahydrofuran) 1.55

Polyvinyl chloride) + 40% trictesyl phosphate 1.55

Epoxy resins 1.55-1.60

Poly(p-methoxybenyl methacrylate) 1.552 Poly(isopropyl methacrylate) 1.552

Poly(p-isopropylstyrene) 1.554

Poly(chloroprene) 1.554-1.558 Poly(oxyethylene)-.alpha.-benzoate-.omega. -methacrylate) 1.555

Poly(p, p'-xylylenyl dimethacrylate) 1.5559 PoIy(I -phenylallyl methacrylate) 1.5573

Poly(p-cyclohexylphenyl methacrylate) 1.5575

Poly(2-phenylethyl methacrylate) 1.5592

Poly(oxycarbonyloxy-1 ,4-phenylene-1 -propyl 1.5602 butylidene-1 ,4-phenylene) PoIy(I -(o-chlorophenyl)ethyl methacrylate) 1.5624

Poly(styrene-co-maleic anhydride) 1.564

PoIy(I -phenylcyclohexyl methacrylate) 1.5645

Poly(oxycarbonyloxy-1 ,4-phenylene-1 ,3-dimethyl- 1.5671 butylidene-1 ,4-phenylene) Poly(methyl .alpha.-bromoacrylate) 1.5672

Poly(benzyl methacrylate) 1.5680

Poly(2-phenylsulfonyl)ethyl methacrylate) 1.5682 poly(m-cresyl methacrylate) 1.5683

Poly(styrene-co-acrylonitrile) (ca, 75/25) 1.57 Poly(oxycarbonyloxy-1 ,4-phenyleleneisobutylidene- 1.5702

1 ,4-phenylene)

Poly(o-methoxyphenyl methacrylate) 1.5705

Poly(phenyl methacrylate) 1.5706

Poly(o-cresyl methacrylate) 1.5707 Polyjdiallyl phthalate) 1.572 Poly(2,3 -dibromopropyl methacryate) 1.5739

Poly(oxycarbonyloxy-1 ,4-phenylene-1 -methyl- 1.5745 butylidene-1 ,4-phenylene)

Poly(oxy-2,6-dimethylphenylene) 1.575 Poly(oxyethyleneoxyterephthaloyl) (amorphous) 1.5750

(poly(ethylene terephthalate)) (crystalline fiber: 1.51 transverse; 1.64 in fiber direction)

Polyvinyl benzoate) 1.5775 poly(oxycarbonyloxy-1 ,4-phenylenebutylidene-1 ,4- 1.5792 phenylene)

PoIy(1 ,2-diphenylethyl methacrylate) 1.5816

Poly(o-chlorobenzyl methacrylate) 1.5823

Poly(oxycarbonyloxy-1 ,4-phenylene-sec-butylidene- 1.5827 1 ,4-phenylene)

Poly(oxypentaerythritoloxyphthaloyl) 1.584

Poly(m-nitrobenyl methacrylate) 1.5845

Poly(oxycarbonyloxy-1 ,4-phenyIeneisopropylidene- 1.5850 1 ,4-phenylene) Poly(N-(2-phenylethyl)methacrylamide) 1.5857

Poly(4-methoxy-2-methylstyrene) 1.5868

Poly(o-methylstyrene) 1.5874

Poly(styrene) 1.59-1.592

Poly(oxycarbonyloxy-1 ,4-phenylenecyclohexylidene- 1.5900 1 ,4-phenylene)

Poly(o-methoxystyrene) 1.5932

Poly(diphenylmethyl methacrylate) 1.5933

Poly(oxycarbonyloxy-1 ,4-phenyleneethylidene-1 ,4- 1.5937 phenylene) Poly(p-bromophenyl methacrylate) 1.5964

Poly(N-benzyl methacrylamide) 1.5965

Poly(p-methoxystyrene) 1.5967

Hard rubber (32% S) 1.6

Poly(vinylidene chloride) 1.60-1.63 Polyjsulfides ("Thiokol") 1.6-1.7

Poly(o-chlorodiphenylmethyl methacrylate) 1.6040

Poly(oxycarbonyloxy-1 ,4-(2,6-dichloro)phenylene- 1.6056 isopropylidene-1 ,4-(2,6-dichloro)phenylene))

Poly(oxycarbonyloxybis(1 ,4-(3,5-dichiorophenylene)) 1.6056 Poly(pentachiorophenyl methacrylate) 1.608

Poly(o-chlorostyrene) 1.6098

Poly(phenyl . alpha. -bromoacrylate) 1.612

Poly(p-divinylbenzene) 1.6150 The multilayer films are usually made by a chill-roll casting technique in which melts of the thermoplastic resinous material from two or more extruders are collected by a feedblock which arranges them into a desired layered pattern. The very narrow multilayer stream flows through a single manifold flat film die with the layers simultaneously spread to the width of the die and thinned to the final die exit thickness. The number of layers and their thickness distribution can be changed by using a different feedblock module. Suitable feedblocks are described, for instance, in U.S. Patent Nos. 3,565,985 and 3,773,882. The feedblocks can be used to form alternating layers of either two components (i.e. ABAB . . . ); three components (ABCABCA . . . or ACBACBC . . . ) or more. Usually, the outermost layer or layers on each side of the sheet is thicker than the other layers so as to form a relatively thick skin. The resinous material used to form the skin may be one of the components which makes up the optical core, or a different polymer which is utilized to impart a desirable mechanical, heat sealing or other property, or a combination of these. Preferably, the present film is made by a process diclosed in US Patent 3,801 ,429, incorporated herein by reference.

In accordance with the present invention, iridescent films with unique color effects are achieved by laminating together at least two multilayered optical stacks as described above, in which each of the optical stacks is characterized as having one dominant wave length band which is reflected from the film. Accordingly, the iridescent film of the present invention is characterized as having at least two reflection peaks. While two multilayered optical stacks having distinct reflection peaks can be used to form the laminate film of this invention, it is further within the scope of this invention to laminate three or more multilayered optical stacks, each of which has a distinct reflection peak. In accordance with this invention, the multilayered optical stacks each have a distinct reflection peak which differs from the reflection peak of the other multilayered stack or stacks by at least 25nm. Differences in the wavelengths of the reflection peaks of each multilayered stack which form the laminate of this invention can also be at least about 50nm, 75nm, 100nm, and up to 300nm or more.

The manner in which each of the multilayer films are laminated or otherwise attached to each other can vary and can be accomplished by methods well known in the art of lamination. Thus, for example, the multilayered optical stacks may be formed continuously as previously described and the separately formed optical stacks may be combined at a common feedblock while still in a molten state. Alternatively, the multilayered optical stacks can be formed separately, cooled, and then laminated into the multilayered films of this invention by means of a transparent adhesive, placed between the individual stacks. Transparent adhesives are well known in the art and include urethanes, epoxies, and acrylics. The particular adhesive does not form a part of the present invention so long as the adhesive is transparent and does not adversly affect the reflection peaks of the laminated films. A problem with forming multilayered films with distinct colors is the color uniformity of the individual optical stacks that are used to create the combination colors. Iridescent combination colors are very sensitive to variation in any of the optical stacks that generate the individual reflection peaks. Slight changes can result in very different reflection colors. Color uniformity of each optical stack is important in achieving the desired combination color. The development of single peak iridescent reflection films with uniform color allow the realistic combination of two or more distinct reflection peaks to create new iridescent colors that could not be created before, with the resultant combination color having satisfactory color uniformity across the entire web width. Methods of achieving color uniformity across the web are known and presently in practice. Orientation of the films both uniaxally and biaxially as well as heat treatment of the multilayer films have been used to improve color uniformity. Particularly useful films that can be used to form the laminated films of this invention are manufactured by Tejin- Dupont Films, Tokyo, Japan under the tradename Tetoran MLF. Utility: The present invention may be used in flexible and rigid decorative packaging. Flexible decorative packaging includes but is not limited to wrapping paper, ribbons, and bows. Rigid decorative packaging includes but is not limited to cosmetic and personal care containers such as for skin care products such as facial mask, UV protective lotion, liquid soap, and antimicrobial product; hair care products such as shampoo, conditioner, hair spray or fixative, and hair colorant; makeup products such as nail polish, mascara, eye shadow, and perfume; shaving cream, deodorant, baby oil, and dental products. The present film may also be used in printed and laminated board for use in packaging. The present invention may also be used in graphic applications such as book covers. The present film may also be used in vertical form and fill packaging which is a type of packaging equipment which feed the packaging film into a shaped area where it can be heat sealed in any of several ways and the package is then filled with something and sealed shut. The dimensions of the finished package are determined by the width of the film fed into the machine and the length of the bag is controlled by the speed and frequency settings at the sealing head. Numerous items may be packaged into a finished iridescent film pouch or bag in this way. The present film may also be used in fashion accessories such as sequins and threads. The present film may also be used in picture frame profile wrapping. Also, the present invention may be sized reduced in some manner to form glitter particles. These particles are of various size and shape depending on the application. The size ranges from very small, approximately .004", to larger particles.

The present film may also be used as a label for various containers. Such containers include but are not limited to cosmetic and personal care containers such as for skin care products such as facial mask, UV protective lotion, liquid soap, and antimicrobial product; hair care products such as shampoo, conditioner, hair spray or fixative, and hair colorant; makeup products such as nail polish, mascara, eye shadow, and perfume; shaving cream, deodorant, and baby oil. The containers may contain effect pigments such as titanium dioxide coated mica; iron oxide coated mica; iron oxide coated titanium dioxide coated mica as disclosed in commonly assigned US Patent 4,146,403 to Louis Armanini et al.; iron oxide or titanium dioxide coated glass as disclosed in commonly assigned US Patent 5,753,371 to William J. Sullivan et al.; platy metal oxides as disclosed in commonly assigned US Patent 5,611 ,851 to Carmine DeLuca et al.; bismuth oxychloride effect pigments as disclosed in commonly assigned US Patents 6,572,695, 6,579,357, and 6,582,507 to Paul Cao; optically variable pigments as disclosed in commonly assigned US Patents 6,325,847 and 6,440,208 to James D. Christie et al.; the dielectric reflectors of US Patent 6,132,873; substrates coated with silicon dioxide and then iron oxide or titanium dioxide; and substrates coated with titanium dioxide or iron oxide and then silicon dioxide; all incorporated herein in their entireties; FIREMIST® pearlescent pigments (comprise calcium sodium borosilicate and titanium dioxide) commercially available from BASF Catalysts LLC; MAGNAPEARL® 1000 pearlescent pigment (comprises 70-80 weight percent mica and 20-30 weight percent titanium dioxide,) commercially available from BASF Catalysts LLC; MAGNAPEARL® 1100 pearlescent pigment (comprises 67-75 weight percent mica, 0.2-2.0 weight percent tin oxide, and 25-31 weight percent titanium dioxide) commercially available from BASF Catalysts LLC; MAGNAPEARL® 2100 pearlescent pigment (comprises 56.5-64.5 weight percent mica, 0.2-2.0 weight percent tin oxide, and 35.5-41.5 weight percent titanium dioxide) commercially available from BASF Catalysts LLC; and platy titanium dioxide commercially available from BASF Catalysts LLC. The present invention may also be used on a colored substrate including a transparent container filled with colored liquid.

The present film may also be used in heat lamination to paperboard and other substrates. In this process, the film may be fed as a complete web into a nip, where under heat and pressure the film may be permanently adhered to a second substrate such as paperboard. This method offers a cost effective substitute for lamination processes requiring the use of adhesives to form the interlayer bond.

EXAMPLES Example 1

The combination of a multilayer coextruded light-reflecting film with a red interference color having a peak wavelength at 610nm and a multilayer coextruded light-reflecting film with a violet interference color having a peak wavelength at 440nm were laminated together with a water-based urethane adhesive to generate iridescent magenta. It is not possible to have a magenta colored film with one peak wavelength.

Example 2 The combination of a multilayer coextruded light-reflecting film with a red interference color having a peak wavelength at 610nm and a multilayer coextruded light-reflecting film with a green interference color having a peak wavelength at 540nm were laminated together with a water-based urethane adhesive to generate an iridescent gold.

Example 3

The combination of a multilayer coextruded light-reflecting film with a green interference color having a peak wavelength at 540nm and a multilayer coextruded light-reflecting film with a violet interference color having a peak wavelength at 440nm were laminated together with a water-based urethane adhesive to generate a shade of turquoise.

The above examples resulted from lamination of two commercially available iridescent films. Optical modeling was also conducted to demonstrate the utility of this invention. The following examples resulted from using TFCaIc to model possible laminated structures.

Example 4 (Modeled) This model is optically equivalent to taking a multilayer coextruded light- reflecting film with a red interference color having a peak wavelength of 610nm and combining it with an iridescent film with a peak wavelength of 650nm. Here, the generated shade is also red, but the combined film has a higher chroma than the single peak film.

Example 5 (Modeled)

This model is optically equivalent to taking a multilayer coextruded light- reflecting film with a green interference color having a peak wavelength of 540nm and combining it with an iridescent film with a peak wavelength of 750nm. Here, the generated shade is also green at normal incidence because the second peak is off in the IR region. Unlike the single peak green film that goes colorless after passing violet at higher incident angles, the combined films have extended color travel that goes closer to red.

Example 6 (Modeled)

This model is optically equivalent to taking a multilayer coextruded light- reflecting film with a violet interference color having a peak wavelength of 440nm and combining it with an iridescent film with a peak wavelength of 700nm. Here, the generated shade is also violet at normal incidence because the second peak is off the IR region. Unlike the single peak violet film that quickly goes colorless at higher incident angles, the combined film color travels through red, orange and yellow.

Claims

What is claimed is:

1. An iridescent film with multiple reflection peaks.

2. The iridescent film of claim 1 comprising at least two multilayered optical stacks wherein each of the optical stacks is characterized as having one dominant wave length band which is reflected from the film.

3. The iridescent film of claim 2 wherein each of the optical stacks has a distinct reflection peak which is different from the reflection peak of the other optical stack or stacks by at least 25 nm.

4. The iridescent film of claim 3 wherein each of the optical stacks has a distinct reflection peak which is different from the reflection peak of the other optical stack or stacks by at least 50 nm.

5. The iridescent film of claim 4 wherein each of the optical stacks has a distinct reflection peak which is different from the reflection peak of the other optical stack or stacks by at least 100 nm.

6. The iridescent film of claim 5 wherein each of the optical stacks has a distinct reflection peak which is different from the reflection peak of the other optical stack or stacks by at least 300 nm.

7. The iridescent film of claim 2 wherein the multilayered optical stacks are combined at a common feedblock while still in a molten state.

8. The iridescent film of claim 2 wherein the multilayered optical stacks are formed separately, cooled and then laminated into the iridescent film by means of a transparent adhesive, placed between the individual stacks.

9. The iridescent film of claim 8 wherein the transparent adhesive is selected from the group consisting of urethanes, epoxies and acrylics.