CA2100061A1

CA2100061A1 - Lamellar polymeric body and method of production

Info

Publication number: CA2100061A1
Application number: CA002100061A
Authority: CA
Inventors: Walter J. Schrenk
Original assignee: Individual
Current assignee: Dow Chemical Co
Priority date: 1991-01-22
Filing date: 1991-12-18
Publication date: 1992-07-23
Also published as: AU1151392A; EP0647183A4; US5316703A; DE69130118D1; DE69130118T2; JP2993736B2; WO1992012857A1; EP0647183B1; MX9200263A; FI933294A0; US5217794A; ATE170455T1; JPH06506408A; CN1063449A; FI933294A; EP0647183A1; NO932637D0; KR930703147A

Abstract

A lamellar polymeric body which may be reflective and which contains no metals and method of making it are provided. The body can be fabricated and/or post-formed into a variety of parts without alteration of its appearance. The body (60) includes discontinuous layers of at least one polymeric material (62) within a matrix (64) of another polymeric material, which polymers differ in refractive index. The layers of the polymeric material may be either optically thick, optically thin, or optically very thin.

Description

~. ~

~ WO92/12~57 2 i ~ ~ ~ 6 ~ PC~/lJS91/0~97 LAMELLAR POLYMERIC BODY AND METHOD OF PRODUCTION

The pre~ent invention relates to a multilayered polymeric body of optically thick, thin, and/or very thin plate-like or ribbon-like 'ayer~ of one or more polymers within a matrix of another polymer, which body reflects light and can be fabricated to have a silvery or hued (that is, gold, copper, etc.~ metallic appearance, or a nonconventional hued (that is, blue, green) appearance, or even an iridescent appearance, ~nd to methods of producing such a polymeric body.
Conventional method~ for fa~rlcatlng reflectlve surfaaes include ~orming such ~urface~ of highly polished metala. Becau~e of the high cost~ and -~ 15 fabricating problems involved in using metal~, more recently fabricators have used plastic surfaces whlch contain thin coatings of metal thereon. ~hus, metal coated plastic articles are ~ow commonly found as ~oth decorative and functional items ln a number of industries. Such articles are used as brlght work for consumer appllan¢es such as rerrlgerators, dlshwashers, wa~hera, dry~r~ and radlo~. Th~se types Or artlclea are WOg2/12857 PCI/U~')l/0~597 ~ 2-alelo used by the automotive industry as head lamp refLectors, bezels, radio knobs and automotlve trim.
Typically, such metal coated plastlc artlcles are formed by electroplatlng or by the vacuum, vapor, or chemical deposition of a thin metal layer on the surface of the article. Additionally, such coatings are subject to the chipping and flaking of the metal aoatlngs as well as corroe~ion of the metal over time. If addltlonaL
protective layers must be applled over the metal coatlng to protect lt, additional labor and materlals costq are involved. Further, there may be environmental dispos2l problems with some metal deposition processes.
One such vacuum metallized deposition system to produce bright work and automotive decor~tive trim is taught by Eisenfeller in U.S. Patent Nos. 4,713,i~3, 4,431,711, and 4,407,871. That sysl;em depos ts minute specular islande~ of indium metal on a dielectric substrate. The metal is then encape~ulated in a ciear polymer.
The preparation of multilayler artlcles of polymers are known, as are methods and apparatu~e~ for making such article~. For example, such multilayered articles may be prepared utilizing multilayer coextrusion devices as descr.bed in commonly-a-~slgned U.S. Patent Noa. 3,773,882 and 3,884.606 to Schrenk.
Such devices are capable of ~lmultaneously extrudlng diverse thermoplastic polymeric mater!als ln continuous layer.~ having ubstantially uniform layer thicknesses.
Thé number of layer~ may be multiplled by the u3e of a device as de~cribed ln oommonl~J-a~aigncd U.S. Patent No.
3,759,647 to S¢hrenk et al.

2 1 ~'~ O 0 6 l P~/US91/0~5~7 Im et al., U.S. Patent No. 4,540,623, teache3 a multllayer laminated artlcle whlch lnclude3 a polycarbonate as one Or the alternatlng contlnuou3 layers. The article~ of Im, however, are lntended ts be transparent rather than reflectlve and to exhibit optical properties comparable to a pure polycarbo~ate polymer.
Alfrey, Jr. et al, U.S. Patent No. 3,711,176, teaches a multilayered highly reflective thermoplastLc body fabricated u~ing thin .Llm technique4. That i9.
the reflective thin film layers of Al~rey, Jr. relied on the conQtructive interference of light to produce reflec~ed visible, ultraviolet, or infrared portionQ of the elQctromagnetic spectrum. Such reflective thin films nave found use in decorative items 5ecause:of the iridescent reflective qualitie~ of the film.
The films of Alfrey, Jr. are extremely sensitive to thickness changes, and it is characteristic of 4uch films 'o exhibit streaks and spot~ of nonunlform color. Further, color reflecte~ by such ~lims !g dependent on the angle of incidence of llght lmpinglng on the film. Thus, ~uch films are not practlcal for uses which require uniformity of reflectivLty.
Moreover, such films are not practical ~o thermoform into articles where unlformity of light reflectance i9 needed as localized thinnins of the iayers during thermoforming cau~es alteratlons Ln the reflective 3 characteristic3 of the films.
Moreover, both the Alfr~y, Jr. et al rLlms and the multilayer rilms and articles made up sub~tantially contLnuou~ layer~ have ~ome llmltlng characteristlc4 inherent ln thelr con4tructlon. ~he ;

W092/12857 PCrtUS9l/09597 ~ C~3~3~ 4 continuous layer3 must adhere to themselve~ to hoLd ~he film together. Thi~ may necessitate the use of intervening adhesive layers which could adver3ely affect the optical properties of the fllm and certainly add to the overall thicknes~ of the film. Further, no gas or other fluid can be permitted at the interface between any of the layers as this may contribute to the delamination of the layers. Additionaily, each of the materials used in the layers exerts an ef~ect on the overall mechanical properties Or the film. For example, if one of the polymers used i9 brittle. the layer3 of brittle material will have an effect on ~ne overall properties of the multilayer film.
Accordingly, there remains a need in the art for a polymeric re~lective film, ~heet or body which can ~e fabricated into a variety of part~ and ~hich can exhibit a uniform reflective appearance or a silvery iridescent appearance over a range of processing conditions and part geometry. There is aiso ~ need for a polymeric reflective film or body wAich will ~old together even if some or all of the Lndividual layers do ~,~ not, there is a need for a body in which gas or other ~luid can be present at 'ayer interfaces without adversely affecting the optical and mechanical , .
properties of the body, and there is a need for a multilayer reflective body which has mechanical propertieq which are substantially independent o~ the mechanical propertles of at ieast some of the layers in the body.
The present lnvention meets those needs by providlng a lamellar reflective polymeric body containing no metals. and a method of makLnB that body which polymer-c body can be rabricated and/or po~t-,.. .
;,~

WO92/12857 2 ~( O ~ PCT/IJS~I/09597 formed into a variety of parts. In one embodiment Orthe invention, ~uch fabrlaation and/or po3t-forming can be accomplished without alteratlon Or lt3 un$form reflective appearance. The body comprl~es diqcontinuous layer~ of at least one polymeric material within a matrix Or another polymeric material which polymers differ in refractive index, The layers of the polymeric material may be either optically thlck, optically thln (that i9, iridescent interference 'ayers) or optically very thin. The optically thick layers are too thick to cauqe viqible lride~cent e~fect3 (1/isuaily perce ved as a variety of colors). whlle the very thin layer~ are too thin to cause such effects. The resulting ~ultilayered lamellar polymeric body, depending upon the layer thickne~es ~elected, may reflect ~ubstantially white light and exhibit a sllvery, metallic appearance, or may have band~ of iridescent color.
In another embodlment of tne nvent.on, where optical propertles are not important, ~he ~iscontinuous multilayer oonstructlon provides a number of advantageous mechanical proper~ies. Sucn ?roper~ies include high tensile propertie~ in one dlrection but lower in a direction tranqver~e to the discontinuou~
ribbon-like layers, the ability to tailor flexibility and ductility into the body, and the abllity to include overlapping gas barrier layers Lnto the multllayer constructlon.
3 The terms "rerlective", "rerlectivity", "reflectlon", and "refleotance" as used hereln re~er to total reflectance (that i~, ratlo of reflected wave energy to $ncldent wave energy) su~rlclently specular in nature ~uch that the polymeric body has a metallic appearance. ~he u~e of the~e term~ is $ntended to WO92/12857 PCT/US91/Og597 ~ 6 ~^

encompass semi-specular or dlffuse reflection such ag that of brushed metal and pewter. In general, reflectance measurement refers to reflectance of llght rays into an emergent cone wlth a vertex angle of 15 degree3 centered around the specular angle.
k specific intensity of reflectance, when used herein, i~ the inten~ity of reflection which occurs at a wavelength where negligible absorption of light occurs.
For example, a sllver appearing article refleot~
~ubstantially all visible wavelsngths, whereas the introduction of a dye to achieve other metallic hues will necessarily lower reflect.vity of the body at the ab~orbing wavelength~. Wavelengths unaffected by the dye will 5e reflected at essentially the same in~ensity a~ a non-dyed sample. and it is at these unaffected wavelengths to which the intensity of reflection is referring. Likewise, where opticaliy thin (tnat is.
iridescent) layers are present. the -eflectance referred to is the peak reflectance obse~ved.
ln accordance with one a~pe!ct of the present invention, a lamellar reflectl~/e polymerLc body of at least fir~t and ~econd diverse polymerlc material~ ls provided, the body having at least fir~t and second t major surfaces. The body includes a plurality of layers of the first palymeric material within a matrix of the second polymeric material, with layers of the first polymeric material having their major interfaces aligned 3 substantially parallel to the major surfaces of ~ne body.
The number of layer~ o~ the fir~t polymeric material in the body ls ~ufficient 3uch that at least 30 percent o~ light incident on the body i~ reflected. The f , .....

: , .

,. . .

, , , W092/12857 21 ~ ~ O ~;1 PCT/USs)1/095~7 individual layers of the first polymeric material in the body and those portions of the second polymeric materLal sandwiched between the indi~/idual layer~ of the fir~t polymeric material, have an optical ~hlcknes~ of not more than 0.09 micrometers ~that iq, are optically very thin), between 0.09 micrometers and 0.45 micrometers (that is, are optically thin), or not less than 0.45 micrometers (that is. are optically thick).
In a preferred embodiment of the invention, at least 75 percent of the lndlvidual layers of f3rst polymeric material and those portions of seconcl polymeric material sandwiched between the individual layers of first polymeric material have at iea~t an optical thickne~s of 0.45 micrometers or greater or 0.09 micrometers or less to produce a uniformly reflective, metallic appearing body. Alternatively, the individual layers of first polymeric material and por~ions of second polymeric materiai sandwiched therebe~ween should have an optical thickness such that no visiDly perceived iridescence ls reflected ~rom the 30dy. ~n another embodiment of the inventlon, a portion or all of the individual layer~ of fir~t polymeric materLal and second polymeric material sandwiched therebetween have optlcal 25 thicknesses in the range of from 0.09 micrometers to .!., 0.45 micrometers to produce a body which has a colored and/or silvery irldescent appearance.
The first and second poLymeric materials dlr~er 3 from each other in refractive index by at lea~t about 0.03, To increa~e the refractive index mi~match at the layer interfaoes, and thus increase the refleotance of the body, a fluid ~uch a~ air may be present at a , ~, ., , , ' ,, ' ' .

,, WO92/12857 PCT/US91/0~597 ~3f~

plurallty of the major interfaceq of the first and second polymeric materials.
In a preferred embodiment of the 'nvention, the body may comprise from iess than one hundred to sevsral thousand layers of the flrst polymeric material with alternating portion~ of the second polymeric material therebetween. Increasing the number of layers in the polymeric body has been found to increase its reflectivity (that is, the percentage of incident lLgh~
reflected from the body). Thus, by controllin~ the number of layers, the degree of reflectivity of the article may be controlled.
.

The reflective body of the present invention may be made up of two or more generally transparent polymer resins. The polymers u~ed in tAe practice of the present invention may be rigid or elastomerlc, or have ~arying degrees of flexibiiity. ~referred are thermoplastic resins wnich are eapable of oeing post formsd into a variety of shapes. For example, in one embodiment of the invention, the lrst ?olymeric material may be polymethyl methacrylate and the qecond polymeric material may be ~oly~tyrene.
Where the reflective body is used in a situation requiring ga~ impermeability, the first polymeric material may be a gas barrler materlal. ~he many overlapping layers in the body create an effective barrier to the passage of gase~. For example. qultable barrier layer materials such a~ copolymers of erhylene and vinyl alcohol, polyvinylidene chloride, nitrile po1ymers, and ryloos may be used In the multllayer Dody.

. . I
.,, I

"

WO92t12857 2 l ~ ~ 3 6 1 Pcrtus9l/0~5~7 _9_ The layers of the first polymeric material may be present in the form of elongated, flat, ribbon-llke layers which are substantially aont;Lnuous ln a fir~t plane parallel to one of the major 3urfaces of the body and discontinuous in a second plane transverse to the first plane. Alternatively, the layers of the flrst polymeric material may be present in the form of platelet-like layers which are substantially discontinuous along planes generally parallel and transverse to one Or the ma~or surfaces of the body.
In some embodiments of the invent-on it may be desirable to incorporate coioring agents such as dyes or pigments into one or more of the Lndividual lnterior layers of the polymeric body or into the continuous polymeric matrix oP the body. The coloring agenks may be selected to give the polymeric body a metallic appearance other than its normal silvery appearance ~uch as bronze, copper, or gold, for exampie.

Different colors such as 5;ack, 51ue, red, yellow, white, and the iiks may also be used.
Typically, it is most desirable to use pigmented coloring agents in the interior layers to provide opaqueness and a two-sided mirror-like reflective quality and to use dyes for the continuous matrix portion of the body. Coloring agents may be u~ed in combination to provide desirable coloring and optical properties. For example. a pigmented whit0 coloring 3 agent may be used in an lnterior layer while a colored dye, such as blue, yellow, red. or green may be included - in the continuous polymerlc matr.~; to provlde a unlque re~lective colored effect.
;

W0~2/128S7 PCr/US~1/0~597 3~ ~ -10-Further, while in certain embodiments of theinvention the surface of the body Ls ~mooth to ~ive a highly reflective appearance, in some instanoes lt may be desirable to give the surface of the body a roughened or brushed appearance to simuLate a brushed metallic appearance. Further, a solvent may be used to etch the surface of the multilayer body to provide a matte or pewter look to the body. Additionally, the body may be embossed with a variety of patterns to provide deslrable optical effect~.
In another embodiment of the invention, the interior iayers of the re~lective body may include layers of two or more different polymers in a matrix of a third polymer. Thus~ a lamellar reflective ?olymeric body of at least first and second diverse polymeric materials is provided, the body having at least first and ~econd major surfaces. The body comprises a plurality of individual layers withir- a matrix of a third poiyme~ic material, with each individual layer comprising at least three or mors alt;ernating layers of the first and second polymeric ma~erial3 wlthln the matrix.
The alternating layers of the first and second polymeric materials have their major interfaces aligned substantially parallel to the major surfaces of the body, with the number of alternating 'ayers of the ~irst and second polymeric materials being sufficient such 3 that at lea~t 30 percent of light incident on the body i~ reflected. In a preferred embodlment, the lndivldual layer~ of the f!rst and se¢ond polymeric materlals have optical thicknesse~ of not more than 0.09 mlcrometers (that is. are optically very thinl, between 0.09 micrometers and 0.45 micrometers (tna~ is, are opticaily j .

WO92/12857 2 !~ a o ~ ~ 1 PCT/1JS~1/0~5~7 thin), or not less than 0.~5 mlcrometers (that i~, are optically thick). The first and second oolymerlc ', materials differ from each other ln refractlve lndex by at least about 0.03.
. . , In one alternative construction, at least 75 percent of the individual layer~ of the fir~t and ~econd polymeric material~ have an optical thickness of at lea~t 0~45 micrometers to produce a unlformly reflective, metalllc- appearing body. Zn another embodiment of the invention. a portlon or all of the individual layers of firqt polymeric material and second polymeric material sandwiched therebetween have optlcal thickne~es in the range of from 0.09 micrometers to 0.45 micrometer~ to produce a body which ha~ a colored ~nd/or ~ilvery irideqcent appearance.
Again, the ?olymers making up the variou~
layers of the body may be chosen to give the body ~pecific mechanical or optical properties. For exampie, the third polymeric material which makes up the continuous matrix may be e'astomerio to produce a flexible reflective body. Polymers may be ~elected to provide a reflective body which is post formable and/or thermoformable. Also, coloring agents ~uch a~ pigments or dyeq may be incorporated into one or more of the polymeric materials a~ previou~ly de~cribed.
Reflectivity of the body may be controlled by controlling the number of layers of polymers ln the body. Preferably, the body compriqes from le~s than one hundred to qeveral thou~and layers of the ~lrst and ~econd polymerlc materlal3.
Aga-in, in one variatlon of thl~ embodlment of ~he lnventlon, the iayer-~ of the r~ r~t and ~econd WO92/12857 PCr/lJS91/0~5~7 ~ ~s~ 12-polymeric materials are substantlall~ continuous in a first plane parallel to one of the ma,jor sur~aces of the body and discontinuous in a qecond pLane transverse to the first plane to form elongated ribbon-like elements.
In another variation, the layers of the first and -~econd polymeric materials are substantially discontinuous along planes parallel and transverse to one of the major surfaces of the body to form platelet-like elements.
The reflectlve polymeric body of the pre~ent invention may also be fabricated to act a~ a birefringent light polarizer which polarizes a broad band of the electromagnetic spectrum. The polarizer is fabricated of at least .irst and second diverse polymeric materials. with the body having at least first and 3econd major surfaces. ~he body includes a plurality of layers of the first po].ymer c material within a matrix of the second polymeric material, with the layer~ of the first polymeric maLter al having thei~
major interfaces aligned ~ubstantially parallel to the major sur~aces of the body.
The number of iayers of the rlrqt polymeric material is sufficient ~uch that at least 30 percent of light incident on the p,olarizer is reflected in the plane of polarization. The individual layers of the fir~t polymeric material and tho~e portions of the ~econd polymeric material sandwiched between indlvidual layers of the first polymeric material have an optical 3 thickne~s of not more than 0,09 micrometers or at least 0.45 micrometers, with the fir~t and aecond polymerlc materials dlfferlng from each other 'n refractlve lndex by at lea~t about 0.03 ln one plane of the polarizer.
In a preferred embodiment. the dL~ference in refractive index be~ween the ~irst and second polymeric materials W092/12857 2 1~ cr/us~)l/09597 is cau~ed by selecting polymer~ having differing ~tre~3 optical coefflcientq and then ~tretching tho3e materlal~
in a uniaxial direction to orlent the polymeric materials.
The unique arrangement of layers of diverse polymeric materials may also provide a useful body even where reflective properties are not required. The arrangement o~ discontinuouq layers of one polymer ln a continuouq matrix of another polymer permits the 0 fabrication of 50dies which have physlcal proper~ies which are controllable and substantially independent of the material~ u~ed for the discontinuouq layer.
Additionally, because of the continuou~ matrix of the 3econd polymer 3urrounding the layers. delamination of the fir~t and ~econd polymer~ at their re~pective interfaces doe~ not adversely affect the overall body;
cata~trophic delamination of the body does not occur.

Accordingly, for this embodiment of the invention, a lamellar polymer'c bocly of at least ~lr t and ~econd diverse polyme~ic materlal~ 1~ provlded, with the body having at least first and second major ~urfaces. The body include~ a plurality of layer~ of - 25 the firqt polymeric materi~al within a matrix of the second polymeric material. Further, the layer~ of the fir t polymeri¢ material are sub~tantlally dl~contlnuou~
along plane~ parallel and/or transverqe to one Or the major surfaces of the body to form platelet-like 3 element~. The layer3 of the fir~t polymeric material may have their major interfaces allgned substantlally parallel to the major surface~ of the body, although thi~ iq not nece~ary.

WO92/12857 ~ PCT/US~I/0~591 r~

For example ? the polymeric body may be fabricated ~o that the first polymerlo material 13 rubbery (or elastomeric) and the second polymerlc material is brittle. This results ln a polymerlc bod~
which has greater flexibility than one fabricated of the second polymeric material alone. Alternatively, both polymeric material~ may be elastomers. If the matrix polymer is ela3tomeric and the first polymeric material ,: i9 not, the body still posses~es elastomeric propertles.
Where the fir~t polymer is in the form Or dlqcontlnuou~
piatelet-like elements, the body retains elastomeric properties in all direction~.
The preqent invention also provides a ~ethod for the production of a lamellar reflective polymeric body compri~ing the stepq of providing a first 3tream of a first heat pla~tified polymeric mater al and a second ~tream of a 3econd heat ?lastlfied polymeric material, ; and encapsulating di3crete portions of the firqt polymeric material in the second polymeric material by coextruding the polymeric materiala to form a plurality of di~continuous ribbon-like layer~ of the flrst polymeric material within a matrix Or the second polymeric material to form the reflective polymerlc body. The discontinuou~ layers of the first polymeric l material are arranged to have their major interfaces ; aligned qubstantially parallel to the major ~urfaaes of the body such that at least 30 percent Or li~ht lncLdent on the body is re~lected. The indivldual layer-q of the first polymeric material in the body, and tho~e portions of the second polymeric material ~andwlched betwee~ the individual layers of khe flr~t polymerlc materlal, have an optical thicknes~ of not more than 0.09 micrometers~
between 0.09 micrometer.~ and 0.45 micrometer~. or not WO92/12857 2 ~ ~ ~ J (`, 1 PCT/US91/0~5~7 less than 0.45 micrometer~, and the firs., and ~eoond polymeric materials dlffer from eacn other in refractlve index by at least 0.03.
The ribbon-like layers may be further dlvided into a series of platelet-like layers to produce layers which are di3continuous in all major planar dimensions.
This step of dividing the ribbon~like layers into platelet-like layers may be acoomplished, for exa~ple, by pa~sing the ribbon-like layers through a reciprocating reed plate or valve.
In an alternate embodiment of the invention, method for the production of a lamellar reflectivP
polymeric body i9 provided comprising the steps o.
providing a first stream of a first heat ?lastified polymeric material and a second stream of a second heat plasti~ied polymeric material. The ?olymeric materials are coextruded to form alternatlng iayers of the ~irst 2~ and second polymeric materi~ls, and then Lndividual ones o~ the alternating layers of the ~irst and second polymeric materials are encapsulated Ln a thlrd polymeric materlal to form a plurality Or discontlnuous ribbon-like elements of the alternating layer~ of the first and second polymeric materials within a matrix of the third polymeric material to form the reflective polymeric body. The alternating layers of the rirst and second polymeric materials have their major inter~aces aligned substantially parallel to the major surfaces Or 3 the body ~uch that at least 30 percent Or light incident on the body is re~leoted, with the indlvidual layers Or the flrst and ,seoond polymerlc materlal~ having optlcal thicknes~es of not more than 0.09 mlorometers, or between 0.09 micrometers and 0.45 mlcrometers. or not les~ than 0.45 micrometers. The :~irst and second WO92/12~57 PCr/US~I/Og597 ~ l6-polymeric materials differ from each other ln refractive index by at least 0.03.
The ribbon-like elements may be ~urther dlvided into a series of platelet-like element3 to produce element~ which are discontinuous in all major planar dimensions. This may be accomplished by dividing the ribbon-like elements into platelet-like elements i~ by pa~sing tne ribbon-like elements through a reciprocatlng feed plate or valve.
In yet an additional embodiment oP the invention, a methGd for the production of a lamellar reflective polymeric ~ody is provided including the steps of, providing a first stream of a first heat plaqtified polymeric material and a second stream of a second heat plastified polymeric mal;erial. Alternat.ng ~lugs of the first and second polymeric materials are then fed to a flow passage where the slugq are .ormed into discontinuouq alternating layers of the first and -second polymeric materials due to the viscosities of the polymers flowing through the passage. Individual ones of the alternatlng layers oE the flrst and ~econd polymeric materials are then encapsulated in a third polymeric material to form a plurality of discontinuous ribbon-like elements of the alternating layers of first and second polymeric materials within a matrix of the third polymeric material to form the reflective polymeric body. The alternating layers of the first and 3 second polymerlc materlals have their major interfaces aligned substantially parallel to the major surface-q of the body ~ùch that, at lea3t 30 peroent Or llght incident or. the body ~ reflected, with the indlvidual layerY Or the first and second polymerLc materials having optical ~hicknes~es of not m.ore 'han 0.09 micrometers. 5etween WO9~/12857 ~ 3~ 1 P~l/US91/09597 0.09 micrometers and 0.45 micrometers, or not le~s than 0.45 micrometers. The first and second polymeric materials dlf~er from each other in refractiv~ index by at least 0.03.
The feeding alternating slugs of the first and second polymeric materials to a flow passage is accomplished by passing the first and qecond polymeric materials through a reciprocating ~alve. The ~requency of reciprocation of the valve i9 controlled to control 0 the SiZ9 of the alternating layer~.
Accordingly, it s an object of the pre~ent invention to provide ~ polymeric reflective film or body which will hold together even if some or all of the 5 individual layers do not, to provide a body in which gas or other fluid can be present at layer interfaces without adver ely affecting the opl;ical and mechanical properties of the body, and to provide a multilayer reflective body wnich has mechanical properties which -are substantially independent of the mechanical properties of at least some of the ayers ln the body.
Still further, it i5 an object of t;he present lnventLon to provide silvery or metallic appearing articles whlch ~5 do not use metal. These, and other object~ and advantages of the present invention will become apparent from the following detailed descriptlon, the accompanying drawings, and the appended claims.
Fig. 1 is a schematic repre~entation of the apparatus for preparing the polymer.c body of the pre~ent invention;

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WO ~2/12857 Pcr/~J~(3l/o~s~7 Fig. 2 ls a sectional side view of a die suitable for uqe in the preparatlon of the polymeric body of the present invention;
Fig. 3 is a perspective view of one embodiment of the polymeric body as it emerges from a sheeting die;
~ Fig. 4 i~ a sectional side view of a die ; ~uitable for use in the preparatlon of another embodiment of the polymeric body of the present invention;
Fig. 4A i~ a ~ectional view of the distortion of layer interfaces of the first and second polymers flowing in the pa~sages;
Fig. 5 iq a front view of the reciprocating feed plate taken along line 5--5 in Fig. 4;
Fig. 6 i~ a side 3ectional view of a die ~uitable for the production of yet another embodiment of the polymeric body of the ?re~ent invention;
i Figs. 7A - 7C are front views oP the reciprocating feed plate taken along llne~ A--A, B--B, : 25 and C--C in Fig. 6; and ,:, Fig. 8 is a perspective view of another embodiment of the polymeric body of the present invention as it emerges from a sheetlng die.
3 The pre~ent invention provides a hlghly reflective lamellar multilayer polymeric body made up of from le~s than a hundred to ~everal th~u~and layers of at lea~t one polymer wlthln a ~atrlx o~ another polymer, - which polymer~ differ from each other ln refractlve Lndex. The lndividual layer~ of the ?olymeric material WO92/12857 2 ~ ~ q '~ ~) 1 PC~/USg1/09597 , g have an optical thicknes3 of not more than 0.09 micrometers, between 0.09 micrometers and 0.45 micrometers, or not less than 0.45 miorometers, ~here the optical thickness i9 defLned a~ the product of the individual layer thickne~s time~ the refracti~e lndex Or the polymeric material which makes up that layer.
Thus, in its preferred form, the lamellar multilayer reflective polymeric body of the ?resent invention is made up of multiple optically thick and/or optically thin and/or optically very thln layers. For purpoYe~ of optical propertles, that l~. refleotance and tran~mittance, an optically thin fllm can be described as a film thinner than one wavelength of light at which the film will be applied. Thuq, for filmq to be used in the vi~ible wavelength band, a thin film i~ deqcribed in the literature as one whose ~hickness, D, ig less than about 0.5 micrometer or whose optical thickness, ND
` (where N iq the refractive index of the material) is less than about 0.7 micrometers. '~asicek, ODtics of Thin Films (?960) at pages '00 and 139.
,~ ~
Thin film layer article~ descrlbe lridescent interference films which rely on the con~tructlve optical interference of light to produce intense reflected light in the visible, ultraviolet, or infrared portions of the electromagnetic spectrum according to the equation:

~ m )(,V~D~+V~Do) ~" , ' ' , .

W092/12857 PCT/~JS91/0~597 ~ 20-where m is the reflected wavelength in nanometers, N
and N2 are the refractive indlces of the alternatLng polymers, D1 and D2 are the thickness of the respectlve layers of polymerq in nanometers, and m is the order of reflection (m=1,2,3,4,5). This is the equation for light incident normal to the surface of the film. For other angles of incidence, the equation will be modlfled to take into acoount the angle. a~ ls known ln the art.
Each solution of the equation determines a wavelength at which an inten~e reflection, relative to surrounding region~ expected. The intenslty of the reflection i~ a function of the "f-ratio" where, f VIDI
(N~DI+N.tD~ ) By proper qelection of the .f-ratio, one can exercise ome degree of control over the intensity of reflection of the variou~ higher order reflections. For example, first order visible ref1ections of violet (0.38 micrometer wavelength) to red (0.68 micrometsr wavelength) can be obtained with layer optical thicknesses between about 0.075 - 0.25 micrometers.
Iridescent films may also be designed to reflect viqible light at higher order reflectances, although at lower intensities.
A~ can be seen, such thin fllm polymeric bodies are 3trongly dependent upon film (and individual layer) thickness to d?termine reflected wavelength. Such thin films are extr~mely sensitlve to thicknesq changes, and lt is characterl~tic of such thin rilms to exhlblt nonuniform 3treak3 and 3pot3 Or color. Thus, ror certain embodiment-q of the lnYention which utilize optically thin layers, the body will exhlbl~ colored or WO9~/12857 2 ~i O ~ 1 Pcrtus91/o9s97 qilvery iride3cence. 3y designing the layer thlcknesses so that there i9 a gradient in optical thicknesse~
across the layers, a broad-band refle¢tlng, ~i1very iridescent polymeric body may be produced.
In other embodiments of the invention, the multilayer bodies are designed so that they do not display the vivid iridescence which i9 displayed when u~ing optically thin layers. The u~e Or layers ~oo thick or too thin to ¢ause iridescence, alone or ln combinatior with each other result in a re~lection which i~ essentially silver and non-iridescent. This silvery appearance i~ due to nigher order reflections from the thick and/or very thin layers being ~o clo~ely spaced that the human eye perceives the reflection to be essentially non-iridescent.
The optical thickness range which i9 avoided by this embodiment of the invention is A/4 < nd ~ A5/4 where~ A= approximately 0.38 mlcrometers, n 5 re~ractlve index of the polymer, and d - physical thlckne~s of the layer in micrometers. Thuq, in the practice of thi~
embodiment of the invention, a sub~tantlal majority -Or the thick layers have an optical thickne~s (nd) of greater than A5/4, whlle a substantial majority of the very thin layers have an optlcal thickness of les~ than 30 h/4.
. Articles made in accordance with this embodlment Or the lnventlon exhlblt a ul1~rorm ~ilvery reflectlve appearance. The reflective characterl~tics " , . t ,'' , ' . :

/
.

WO92/12857 ~ ~ PCT/US91/~597 . -22-of the multilayer bodie~ of this embodiment of the invention are governed by the following equation:

R=- kr _ xlO0 (l~(k-l)r) where R is the amount of reflected light (percent), k iY
the number of thick film layers, and r =[(Nl-N2)/~N
N2)]2. See Vasicek, optic~_or Thin Film~ (1960) at pages 69-70.
Thi~ equation nd cates that the inten~ity of the reflected light, R, Ls a function only of r and k, where r and 1< are defined as above. As a cloYe approximation, R is a function only of the refractive index mismatch of the two ?olymer component~ and the total number of layer interfaces. Thi~ relationship contrast3 greatly with that of opticaily thin film articles whose reflectivity is highly sensitivs to layer ; thickness and angle of view.
Thus, the refiected wavelength of light ~rom thiY embodiment of the multilayer polymeric body o~ the pre~ent ln~ention 1Y independent of both indLvldual layer and total structure thickness over a wlde processing range. Uniformity of rerlection is inherent in the design o~ the body. Moreover, a gradient of layer thlcknesses through the thlckne~ of the body is neither detrimental nor advantageou to the appearance of the body as long as a substantial majorlty o~ the ind$vidual layers of the polymers malntains an optlcal thickness equal to or greater than about 0.45 mi¢rometer~ or equal to or less than 0.09 mlcrometer~.
ThL~ again contrast~ with the optlcally thin ~ilm e=bodiment oE the inventlon whioh refleot~ broad or : ' WO92/12857 21~ ~ (J~ 1 PCTtUS91/0~5~7 narrow bandwidthq depending upon layer thickne.qs gradient.
The preferred coextrusion proces~ for 1, fabricating the polymeric bodies of the present invention may introduce layer thickness variations both through the thickness of the body and in the plane of individual layers. Variation in layer thicknesses of each polymeric component ¢an be as much a~ 300 percent or more. However, useful reflective bodle~ and articles 0 may be made even with such wide variations as long as a substantial majority of the layerq have an optical thickness of not more than 0.09 micrometers or not less than 0.45 micrometers. With this condition met, there i an absence of viqibly perceived inter~erence color3 ~', reflected from bodies and articles of this embodiment of the present invention.
,~ The absence of the iridescent interference colorA i~ somewhat subjective to the human eye.
However, we have found that about 75 percent of the layer~ in the body should have optical thlcknesses greater than a . 45 miorometers or less than 0.09 micrometers to obtain the broad band, visually uniform reflectance of substantially all wavelengths (white ,~ light) which characterizes this embodiment of the presént inventlon. A minority of about 25 percent or fewer of the layers having optical thicknesses ln the i range of 0.1 to 0.45 micrometers have been found to have 3 inter~erence reflection~ of a sufflcient,ly low intensity ' , 50 that the body wlll have e~sentlally no visibly ,oerceLved lride~cence.
The reflective polymerLc bodie9 Or the pre9ent invention become more highly reflective Or incident i, ', "

WO92/12~57 PCr/US~1/0~597 2 ~ r;~ 6 ~ -24-light (that is, transmit less light) as the number of layers is increased. Preferably. 'che number o~ layers is sufficient to produce an article whLch will reflect at least 30 percent Or the incident light, for tho~e wavelengths for which there is negligible ab~orption.
Reflectances below about 30 percent are not ~ufficient to be readily observed. If it is desired to u3e the reflective polymerio body of the pre~ent inventLon a~ a mirror, adding additional layers will increa~e the reflectance of the body to 50 percent or higher to produce a qilvery, mirror-like appearance.
The reflectivity of the bodies is alqo dependent upon the difference in refractive index between the two polymers used. That is, the greater the difference in refractive index, the greater the reflectivity of the body. Accordingly, it can be qeen that the reflective nature of the polymeric bodies may be controlled by the selection of polymers having differing refractive indices and by fabricating the body to have additional layers.
The reflective multllayered polymeric bodie~ of the pre-~ent invention may comprise alternatlng layers of a wide variety of generally transparent thermoplastic materials. Suitable thermoplastic reqins, `Y along with repre~entative refractive indlceq, whlch may be used in the practice of the pre~ent lnvention include, but are not limited to: perfluoroalkoxy re~ins - 3 (refractive index _ 1.35), polytetrafluoroethylene (1.35), fluorinated ethylene-propylene copolymers (1.34), ~lllcone resin~ (1.41), polyvlnylLd~ne fluoride (1.42), polychlorotrlfluoroethylens (1.42), epoxy re~inq (1.45), poly(butyl acrylate) (1.46), poly(4 methylpentene-1) (1.46), poly(vinyl acetate) (1.47), ~ ' .

. , f , WOg2/12857 2 ,L ~ n o ç; 1 PCr/US~ 5~7 ethyl oellulose (1.47), polyformaldehyde (1.48).
polyisobuty:L methacrylate (1.48), polymethyl a¢rylate (1.48), polypropyl methacrylate (1.48), polyethyl methacrylate (1.48), polyether blook amide (1.49), polymethyl methacrylate (1.49), cellulose acetate (1.49), cellulose propionate (1.49), cellulose acetate butyrate (1.49), cellulose nitrate (1.49), polyvinyl butyral (1.49), polypropylene (1.49), polybutylene (1.50), ionomeric reqin3 quch as Surlyn (trademark) (1.51), low den~ity polyethylene (1.51), polyacrylonitrile (1.51), polylsobutylene (1.51)~
thermoplastic polyester~ such a~ Ecdel (trademark~
(1.52), natural rubber (1.52), perbunan (1.52), polybutadiene (1.52), nylon (1.53), polyacrylic imides 1~ (1.53), poly(Yinyl chloro acetate) (1.54), polyvinyl chloride (1.54), high density polyethylene (1.54), copolymer~ of methyl methacrylate and styrene (1.54), tran~parent acrylonitrile-butadiene-styrene terpolymer (1.54), allyl diglycol resin (1.55), blends of polyvinylidene chloride and polyvinyl chloride suah as Saran resins (trademark) (1.55), polyalpha-methyl qtyrene (1.56), ~tyrene-butadLene latexe~ such as Dow 512--K (trademark) (1.56), polyurethane (1.56), neoprene (1.56), copolymers of qtyrene and acrylonitrile ~uch a~
Tyril reqin (trademark) (1.57), copolymers of styrene and butadiene (1.57), polycarbonate (1.59), other thermoplastlc polyeqters ~uch as polyethylene terephthalate and polyethylene terephthalate glycol (1.60), poly~tyrene (1.60), polyimide (1.61), polyvinylidene cnloride (1.61), polydichlorostyrene (1.62), poly~ulPone (1.63), polyether qul~one (1.65), and polyetherlmlde (1.663. The re~ractive lndlces reported above may vary somewhat at difrerent wavelengths. For example, the refractlve index of W092/12857 PCT/US~I/0')597 ~ 26-polycarbonate i9 somewhat greater for llght ln the blue region of the ~pectrum and .~omewhat lower for light In the red region of the spectrum.
Copolymers of the above resins are also useful such as hydrolyzed ethyiene vinyl acetate, styrene and hydroxy ethylacrylate, styrene and maleic anhydride, qtyrene-butadiene block copolymers, ~tyrene and methyl methacrylate, and styrene and acryllo acid. Other useful polymeric materialq include polyetheretherketones, 0 polybutene, maleic anhydride grafted polyolefin~ such as Admer (available from Mitsui Chemicals) and Plexar (available ~rom Quantum Chemicals), and copoiymers of ethylene and ~inyl acetate such a CXA (available lrom du Pont). The latter three polymers are particularly useful aq adhe~ive layers to bond other polymeric layers together in the multilayer construction.
A condition for the selection of the polymers to make up the layers and matrix of 'he body i~ 'hat the polymerq ~eleated have refractlve lndloeq whlcn differ ` from each other by at lea~t about 0.03. Further. the polymers ~hould be compatible in proces~ing temperatures ~o that they may be readily coextruded.
Multilayer bodie~ in accordance with the preqent invention are mo~t adYantageously prepared by employing principle~ ~imilar to those de~cribed ~n U.S.
Patent Nos. 3,565,985, 3,759,647, 3,773,882, and 3,884,606, with respect to multilayer aoextru~ion, the disclosures of which are incorporated herein by reference. Such device3 are capable Or provldlng ~ubStantially contLnuou.~ multilayered, ~imultaneou~ly ~`
, ., .
' .

~ . W092/12857 PCr/US9l/09597 -2 ~JJ~l extruded thermopla~tic materials having controllable layer thicknesses.
An apparatus for carryLng out one embodLment of - the process of the present lnventlon Ls illu3trated irl , 5 Fig. l. There, an apparatus 10 for the preparation of ; the multilayer polymeric body of the present invention is depicted. Apparatus lO includes, in cooperative combination, first, second, and optional thlrd source~
o~ heat plastified polymerlo resins for extruders ll, -` 12, and 13, respectively. Optional third source af polymer resin is used when lt is desired that the ~lrst and second polymers adhere to each other in the final polymeric body. Thus, a "glue" layer of a third polymer may be interpo~ed between the fir~t and second poiymers aq explained in further detail below.
` Extruders 11, 12, and 13 discharge the heat plastified polymeric resins into conduits 14, 15, and 16, respectively. A coextrusion feedblock die 17 is in operative combination with conduits l4, '5, and 16 and receives first, seoond, and optional third heat plastified streams therefrom. Dle 17 deflnes an extrusion orifice 18 from which Ls~ues a compo~ite stream of polymeric material having ribbon-like layers ; of a fir~t polymeric materLal embedded within a matrix of a second poLymeric material. Optionally, the flrst and second polymerq may be adhered together by a "glue"
layer of a third polymer.
From orLfice 18, the comDosLte ~tream passes optionally through a mechanlcal manipulating sectLon 20 which ~erves to rearrange the sriglnal ribbon layer~ in a matrix composite stream into a stream havlng more than the original number of rLbbon layerq as taught in the :, .
. . , , WO92/12857 PCT/~S~1/0~597 ~ ~ -28-aforementioned U.S. Patent Nos. 3,565,985 and 3,759,647, Additional manipulatLng sections may be arr~nged ln 3erie~ to further multiply the number of layers Ln the stream.
The number of additional ribbon iayer~ created using the manipulation devices of the aforementioned patents is determined by the number of rlbbon layers divided by the layer-dividing vane in those devlces.
Ribbon layers not cut by the dividing vane are not multiplied. This i~ in contrast to a ~ub~tantially continuou3 multilayer con~tr~ction in which all layers are cut by the dividing vane. The interfacial area of each ribbon is increa~ed in the lateral spreading region the mechanical manipulating devices. For each layer multiplication ~tage, the width of the ribbon layers is doubled and the thickness is halved, for poiymers having reasonably matched vi~cosities. Where the ribbon layers have a higher visco~ity than the matrix polymer. there will be a correspondingly lesser change in the shape of the ribbon layers after manipuiation.
The multilayered stream Ls t;hen passed lnto a ~haping die 22 which is so constructed and arranged that ~treamlined flow i9 maintained therein. Such an extrusion die is described in U.S. Patent No. 3,557,265, the di~closure of which i9 incorporated by reference heréin. While a ~heet or film forming dLe 22 is illu~trated, it will be appreclated by those ~killed in 3 the art that a forming die of any desired confLguration may be u~e to extrude not only fllms and sheets, but also other profLles and ~h~pe~.
The conflguration of the shaplng die can Yary and can be ~uch a~ to reduce the thickne~ of each Or WO92/12857 2~ 0 0~ 6 1 Pcr/vs~l/0~5~7 the ribbon~ e layers. The precise degree of reduction in thickness of the ribbon-like layer~ dellvered from the mechanical orientLng ~ection. the conflguratlon of the die. and the amount of mechanlcai worklng of the body after extrusion are all factors which affect the ~ thickne~s of the individual layers in the final body.
:,`
Fig. 2 depicts schematically a sectlonal view of die 17 ~uitable for the production oE the polymeric body of the present invention. Die 17 comprises a die 0 body 30 defining a first inlet plenum 32 Ln operative communication with a first polymer source through conduit 14. Die body 30 also de~ines a second or intermediate polymer plenum 34 in operative communication with a second polymer source through conduit 15. An optional third plenum 36 is defined by die body 30 and i~ in operative communication with an optional source of polymer through conduit 16. Where an adhe~ive layer is desired to bond together the first and second polymers, the adhesive polymer is supplied to second plenum 311, while the ~econd polymer i~ supplied from conduit 16 to optional third plenum 36. Remote from inlet plenum 32, discharge plenum 38 terminates ln discharge orifice passage 18.
;
A first dividing means 40 i~ di~posed between ~, inlet plenum 32 and ~econd plenum 34. A ~econd dlvidLng means 42 i~ di~po~ed between second plenum 34 and thlrd plenum 36. An optional third dividing means is disposed ~ 3 between third plenum 36 and discharge plenum 38. First ; dividing means 40 has a plurality of passages 46 which provid~ communlcation between Lnlet plenum 32 and a location withln seoond dlvldlng means 42. The passages ' , .
..

:

W092/12857 Pcr/us~l/o~5~7 ~r~ 30-46 may be either round, square, or rectangular ln cross section and arranged in either rows or ~taggered arrays.
Second dividing means 42 has a piural-ty af passages 48 which provide communication between SeConG
plenum 34 and a location within optional third dividing means 44. Again, the passages may be either round, square, or rectangular in cross section, and may be arranged in either rows or staggered arrays. Optlona third dividing means 44 al30 has a plurality of passages 0 50 which provide communication between third plenum 36 and discharge plenum 38.
ln operation of the die depicted in Fig. 2, a first heat plastified polymeric resin is supplied through conduit 14 into inlet plenum 32. From ?lenum 32, the polymeric material flows through passages 46 and is discharged within passages 48. A second heat plastified polymeric resin is supplied through conduit : 20 15 into intermediate plenum 34. The second polymer flows through pa-~ages 48 around th~ discharge points of the first polymeric material and eneapsulates the ribbons of the first polymer in a continuous matrlx.

Where an intermediate "glue" or adhesive layer is desired, the adhesive polymer is supplied through conduit 15 into intermedLate plenum 34, and the seaond heat plastifled polymer is supplied through conduit 16 into third plenum 36. In this embodiment, the -qecond polymer flows around and encapsulates ribbons of the first polymer, now coated with a layer of an adheslve polymer, and encap~ulate~ the two ln a continuous matrix.

WO92/12857 ~l 0 ~ 6 l Pcr/us~l/09591 By maintaining the total sxtrusion rate ~o that turbulence does not occur in the plenums, a oomposite stream made up of multiple ribbon-~ike layers of a first Dolymer in a continuous matrix of a ~econd polymer i3 formed and discharges through orifice 18. After further optional mechanical manipulation in section 20 to further increa~e the number of layers as previously described, the composite polymer stream is discharged through shaplng die 22 to form a polymeric body as illu~trated in Fig. 3.
As shown in Fig. 3, the polymeric body 60 includes a plurality of layers of a first polymeric material in the form of sub~tantially continuous ribbons 62 embedded in a matrix 64 of a second polymer. As shown, the ribbon~ are substantially continuous in a ~irst plane parallel to a major horizontal ~urface of the body and are discontinuous in a plane tran verse thereto. The cross sectional shape and dimensions of the ribbon~ 62 are determined by the relative flow rate~, the flow patterns within the manipulating ~ection, and the ~haping dle a~ well as the vi9coslty and elasticity of the polymers and l;heir lnterfaclal ten~ion.

~.~
Spreading flow in the manipulating ~ection or within the ~haping die increases the width Or the ribbons and decreases their thickness. Veloclty profiles within the dies and layer multlplication 3 sections Or the apparatus may affec~ the shape of the edges of the ribbon~.
In a preferred embodiment oP the inventlon, a reflective multilayered polymerlc body l~ produced whlch reflect~ at least 30 percent af the light incident ,, , W092/12857 Pcr/us~l/o~5~7 ~ 3 -32 thereon. The thicknesseQ of the layers of first polymeric material and tho3e portions of the 3econd polymeric materlal sandwiched bstween layers cr the first polymeric material are controlled ~o that the individual layers of first polymeric material and portions of second polymeric material therebetween have an optical thickness of not more than 0.09 mLcrometers, optical thicknesses between 0.09 micrometers and 0.45 ~icrometer~, or optical thicknes~es not less than 0.45 micro~eters. The fir3t and second polymeric material have refractive indices which differ by at least 0.03 In another embodiment of the invention, the ribbons 62 themQelves may comprise a microlayer ~tructure of alternating fir~t and second polymeric materialQ, with the individual layers having opt~cal thickne~iQes of not more than 0.09 micrometers, between 0.09 micrometers and 0.45 micrometers, or not le~s than 0.45 micrometer~ as desired. The fir~t and second polymeric material have refractive indice~ which differ by at lea3t 0.03. In this embodiment of the lnvention, the polymeric body will comprlse muLtiple overlapp~ng layers of ribbons having layer~ of alternating rlr~t and ~econd polymeric material~ embedded in a matrix o~ a third polymer. The microlayer stream may be created by i using the techniques taught in the aforementloned U.S-Patent NOQ . 3, 565, 985, 3, 759, 647, 3, 773, 882, and 3, 884, 606 .
3 The controlled ribbon-like morphology of the polymeric body of the present inventlon, whether comprLs~ng ribbon~ o~ ~ingle polymers or multllayered ribbon~, re3ults in a ~tructure havLng many useful ani~otropic propertie~. Becau~e the many overlapplng ribbons are continuou~ in the extru~ion dlrection of 'he WO9~/12857 2 l ~ ~ O n ~1 Pcr/vs~1/o~)ss7 body, but dlscontinuous in the transver~e dlrection, tensile properties of the body may be hlgh in the extrusion direction but lower ln the transver~e direction i~ suitable polymer.s are seleoted. If ribbons are made from liquid cry~talline polymers such a~ those polymers available from Celanese Corporation under the designation Vectra~ very high tensile properties in the extru~ion direction are obtained, Further, the matrix polymer embedding the rlbbons prevents catastrophic delamination.
In a further embodiment of the invention illustrated in Fig. 4, where like reference numerals repre~ent like elements, a polymeric body having r.bbons ~hich are lamellar in cross section may also be produced by po3itioning a reciprocating valve or feed plate 70 ahead of fir~t dividing means 40 in die body 30.
Reciprocating ~eed plate 70 comprises a serie~ of alternating holes 72 and slots 74 as best seen in Fig.
5. Holes 72 are in communication with the first polymer stream in plenum 32. Slot~ 74 are in communication with the second polymer stream enterLng Lntermediate plenum 34 through conduit 76. A~ feed pia~e 72 i9 reaiprocated (by conventional means not ~hown) back and forth, passages 46 are alternately fed "~lugs" of the fir~t and second polymer. Because Or the ViQCoYity Or the polymer3, there will be a parabolic veloclty profile within pas~ages 46 which will dLstort the interfaces between the polymers into a layered ~tructure as shown in Fig. 4A. Frequency Or the reciprocation of feed plate 70 may be u3ed to con~rol strlatlon thlckne~a.
The~e layered ribbons may then be encapsulated wlthln a continuou~ matrix of ~econd polymer as descrlbed above.

W09~/12857 PCT/US91/09597 , ~, In another embodiment of the in~ention illu~trated in Fig. 6, where like reference numerals refer to like elements, the fir~t polymeric materlal may be made to be discontinuous in all major planar directions of the body, producing layers of platelet-like elements in a continuous matrix of a second polymer. As shown in Fig. 6, a stationary feed plate 70 iq po~itioned at the outlet end of pa~ages 48.
Reciprocating feed plate 73 (shown in Flg. 7B) i9 po~itioned behind stationary feed plate 70.
Reciprocating feed plate 73 compri~es a 3erLes of staggered openings which alternately communicate with -either the encapqulated tubes of polymer from holes 72 or polymer from slots 74 in feed plate 70. A stationary plate 78 (shown in Fig. 7C), having rows of holes 80 is located behind reciprocating feed plate 73.
.
A first polymer is fed from plenum 32 into passages 46 and then encapsulated by a ~econd polymer introduced through conduit 15 into intermediate plenum 34. At the outlet end of pa~sages 48, rows of the first - polymer encapsulated within the second polymer are alternately ~paced between slots communlaatlng wlth a third polymer source, where the thi;rd polymer may be the same a~ or different from the second polymer. As shown in Figs. 7A - 7C, stationary feed plate 70 comprises alternating rows of holes 72 and vertical slots 74.
Hole~ 7? communicate with the fir~t polymer stream encapsulated in the second polymer whlle slots 74 communLcate with a source of third polymer (which can be the same as the ~econd polymer):through condult 76.
Flow of the polymer through reciprocat1ng plate 73 produceq alternating "~lug~" of encapsulated first polymer with a second or thlrd polymer.

--WO92/12857 ~1 ~ a ~ ~ l P~r~u~91~0~)5g7 - _35_ These discontinuou~ slug~ then flow through manipulating ~ection 20 where the number of layers ls further multiplied, or dlrectly to ~haplng dle 22. ~he first polymer is deformed into discontlnuou~ platelet-like elements within a matrlx polymer. The encapsulating layer of the second polymer acts a~ a lubricating boundary layer so that the first polymer maintains substantially plug flow through the system, The resulting polymeric body ls lllustrated ln Fig. 8, with many layers of overlapping platelets 82 of the first polymer contalned within a matrix 84 of the second polymer. As can be seen, the platelets are discontinuou~ along planes both parallel to and transverse to the major surfaces of the body.
The controlled platelet-like morphology produced by this embodiment of the invention has ~everal utilitles. Where the polymeric body produced is one which is reflective, light is reflected from the many interface~ of the overlapping platelets much like the scales of a silvery appearing fish.
Imperfect adhesion between the first and seoond polymers does not necessarily adver~ely affect the physical or optical properties of the body. For example, a polymeric reflective body prepared from a polystyrene (R.I. 1.59) matrix which contains platelets of polymethyl methacrylate (R.I. 1.49) does not catastrophically delaminate even though in a laminate - having continuous layers of the two polymers. moderate flexing wlll produce delaminatlon. Because of the contir.uous matrix of the ~eeond polymer, the body maintains its lntegrLty~

~YO92/12857 PCr/USgl/095~7 , Further, air, or other ~ases or liquids, may be introduced into the polymer melt formlng the platelet~
When cooled, such gases or liquid~ will come out of solution at the interface between the plateletA and the matrix polymer to provide a very large refractive index mismatch (R.I. air = 1.00). If the matrix polymer is - elastomeric, the polymer making up the platelets can be nonelastomeric and yet the polymeric body will ~till possess elastomeric propertie~ in all directions. The polymer used to form the platelets may be one which i9 a barrier to gases and/or liquids. The many layers of overlapping platelets may provide and excellent barrier to gases because of the tortuous path to gas permeation.
The platelets can themseives be multilayered either by feeding a microlayer stream of alternating layers of diver3e polymers into plenum 32 or by positioning reciprocating feed plates or valves, as shown in Fig. 4 and Fig. 6, at both the inlet and outlet ends of passage3 46. The method o~ the present invention uniquely provides for controlled placement and dispersion of one component ln a continuous matrix of another. The size and placement of the platelet~ ls managed by the mechanical means described above.

. ..
While certain representative embodiments and details have been shown for purposes of illuqtrating the invention, it will be apparent to those skilled in the art that various changes in the methods and apparatus 3 disclosed herein may be made without departing from the scope of the lnvention, whlch is defined in the appended claim~.
"

Claims

1. A lamellar reflective polymeric body of at least first and second diversepolymeric materials, said body having at least first and second major surfaces, the body comprising a plurality of discontinuous layers of said first polymeric material within a matrix of said second polymeric material, and wherein said discontinuous layers of said first polymeric material have their major interfaces aligned substantially parallel to the major surfaces of said body, the number of layers of said first polymeric material being sufficient such that at least 30% of light incident on said body is reflected, the individual layers of said first polymeric material in said body, and those portions of said second polymeric material sandwiched between said individual layers of said first polymeric material, having an optical thickness of not more than 0.09 micrometers, between 0.09 micrometers and 0.45 micrometers, or not less than 0.45 micrometers, and wherein said first and second polymeric materials differ from each other in refractive index by at least about 0.03.

2. A lamellar polymeric body of at least first and second diverse polymeric materials, said body having at least first and second major surfaces, the body comprising a plurality of layers of said first polymeric material within a matrix of said second polymeric material, and further wherein said layers of said first polymeric material are substantially discontinuous along planes parallel and/or transverse to one of said major surfaces of said body.

3. Alamellar polymeric as claimed in Claims 1 or 2 in which said polymeric material forming said matrix is elastomeric.

4. Alamellar polymeric as claimed in any of Claims 1-3 in which said first, second and polymeric matrix materials are elastomeric.

5. A lamellar polymeric body as claimed in any of Claims 2-4 in which at least a portion of the layers of said first polymeric material have an optical thickness of between 0.09 micrometers and 0.45 micrometers and produces a colored, iridescent body.

6. A lamellar polymeric body as claimed in any of Claims 1-5 wherein said layers of said first and second polymeric materials are substantially continuous in a first plane parallel to one of said major surfaces of said body and discontinuous in a second plane traverse to said first plane.

7. A lamellar polymeric body as claimed in any of Claims 1-6 wherein said layers of said first and second polymeric materials ate substantially discontinuous along planes parallel and traverse to one of said major surfaces of said body.

8. A lamellar polymeric body as claimed in Claim 2 in which at least 75 percent of said individual layers of first and second polymeric materials have an optical thickness of at least 0.45 micrometers.

9. A lamellar polymeric body as claimed in Claim 1 in which a fluid is present at a plurality of said major interfaces of said individual layers,

10. A lamellar polymeric body as claimed in Claim 1 in which said first polymer material is a gas barrier material.