US2687673A - Textile material having oriented fibers - Google Patents

Description

1 350-404 SR C SEARCH ROOM Aug. 31, 1954 P. BOONE 2,687,673

' TEXTILE MATERIAL HAVING ORIENTED FIBERS Filed April 4, 1949 6 Shuts-Shoot 1 IN VEN TOR -Ph/'//,0 Boone A T TORNE Y a- 31, 1954 P. BOONE 2,687,673

TEXTILE MATERIAL HAVING ORIENTED FIBERS Filnd April 4, 1949 6 Sheets$hut 2 J INVENTOR Phil/,0 Boone 9 BY Maw ATTORNEY 31, 1954 P. BOONE TEXTILE MATERIAL mwmc oammn FIBERS 6 Sheets-Sheet 3 Filed April 4, 1949 /N VENTOI? Phil/p Boone E) v 6&6].

A TTORNEY Aug. 31, 1954 P. BOONE TEXTILE MATERIAL HAVING ORIENTED FIBERS Filed April 4, 1949 6 Sheets-Sheet 4 /NVENTO/-? Phi/1,0 .Boone BY Fig. 33

A 7' TORNE Y P. BOONE TEXTILE MATERIAL HAVING ORIENTED FIBERS Filed April 4, 1949 Aug. 31, 1954 6 Sheets-Sheet 5 INVENTOIP -P/Il'h p BOO 7e 3 r A TTOPNEY Aug. 31, 1954 P. BOONE TEXTILE MATERIAL HAVING ORIENTED FIBERS Filed April 4. 1949 6 Sheets-Sheet 6 I'll. VIIIIIIIIIIIII;

--POWER SUPPLY VIII/III!) IN vE N TOR Philip B 0 one A TTORNEY Fig. 45

Patented Aug. 31, 1954 UNITED STATES PATENT OFFICE TEXTILE MATERIAL HAVING ORIENTED FIBERS 5 Claims.

This invention relates to light-altering materials and more particularly to light-modifyin bodies, areas, filaments, fabrics or the like for producing various color and other effects.

It is well known that birefringent or doublyrefracting substances or components in conjunction with light-polarizing means may be employed to resolve a mixture of light into its color components or to produce other visual effects. It is also known that rotatory-polarizing or optically active substances or elements may be employed with light-polarizing means for a generally related objective. The present invention contemplates the adaptation of the phenomenons of light polarization, double refraction and optical activity to the textile and related arts and the provision of filaments, fibers, yarns, fabrics and other areas of material capable of producing unusual and attractive color, pattern, luster and variable effects heretofore unknown thereto. Components of the invention may be extruded, twisted, folded, spun, coated, interlaced, interwoven, bonded; embedded or otherwise arranged in functional relation to provide various interference colors and other qualities. Filaments and yarns of the type to be described herein may readily be formed and woven together into fabrics and may also be interwoven with conventional filaments and yarns. In certain of the constructions, the interference colors and other effects may be produced by each body or filament alone, and in other constructions they may be produced through the coaction of a plurality of such bodies or filaments as, for example, through their cooperation in a fabric. Thus, a construction of the invention may broadly be considered as constituting a self-sufficient, relatively small body or a plurality of coacting bodies forming a larger body or area.

A wide range of uses for materials of the invention is contemplated inasmuch as their attractiveness and utility are unique, their manufacturing cost should not exceed that of known quality textile materials, and they may be produced by methods generally related to known methods or by the various methods set forth herein. While certain embodiments of the materials are adapted to produce interference effects through reflection of light, it is presently indicated that those forms which produce interference colors and other effects through transmittal of light will have greater acceptance and, accordingly, constructions of the latter type are in the preponderance among those described herein.

Both reflection and transmittal of light for the above-mentioned and other functions may also be performed by various of the examples as will presently be described. In other forms of the materials, reinforcing or supplementary color effects may be obtained by combining known materials such as conventional fibers and dyes therewith.

Among principal contemplated decorative and utilitarian uses for the materials are draperies, curtains, lamp shades, screens, wall panels, window shades, theatrical costumes and properties, and clothing portions and accessories. While the propensities of light-polarizing and doubly-refracting or optically active substances to coact for producing interference colors, and the unusual beauty of said colors have long been recognized, substantially no method has been developed heretofore for making the same available for widespread artistic and utilitarian uses. A principal application has been in the field of microscopy where doubly-refracting objects are examined under polarized light to provide interference color contrast of various regions of the object. Other applications such as may have occurred in the field of optics or elsewhere have been restricted to extremely narrow usage or have possessed limitations which have resulted in their finding little or no acceptance. The marked differences therefrom of products and methods of the invention in such considerations as form, performance and adaptability to significant esthetic and utilitarian uses of the general public are believed to substantiate an inventive concept which is inherently broad in scope.

Inasmuch as variation of orientation of components of the invention produces a variety of visual effects, it will be seen that their embodiment in the form of bodies such as filaments and fabrics offers a multiplicity of directions of orientation not similarly obtainable in other structures. For example, the width of materials of the invention may be as extensive as that of any presently known fabric, which is to say that it is limited only by the capacity of current or to-bedeveloped textile machinery. Continuous lengths of the materials may be formed similarly to other known filaments and fabrics. Functional arrangement of the components to obtain predetermined relative orientations thereof may be adapted to, or facilitated by known procedures of twisting, spinning, coating and stretching filaments and by substantially any type of weaving, knitting, braiding, netting or other known methods. The materials may be formed. to show qualities of drape and stretch in the manner of conventional textile materials and, accordingly, they may be in the form of assemblies capable of being deformed simultaneously in substantially all directions, curved as well as planar, without appreciably affecting inherent or relative orientation of the components.

With reference to the showing of light-polarizing birefringent and optically active components in the drawings, the vibration directions of the light-polarizing components are indicated therein while principal axes of birefringent and optically active components are generally intentionally omitted because they could be operatively represented in several directions depending upon the characteristics of the components. A principal axis of a birefringent or optically active component, relative to the drawings, may generally be considered, for purposes of illustration, as extending either transversely or longitudinally, or in both directions of said component unless otherwise indicated for producing a predetermined color or other effect, said direction or direction or directions providing a given angle of orientation thereof relative to a light-polariz ing component or components which provides an operative assembly. It is to be understood, however, that modifications of said relative orientation may exist and moreover that various crystalline aggregations forming structural patterns or a random disposition of anisotropic particles or the like may be bonded to or incorporated in the component or material to provide a plurality of optic axes extending in a plurality of functional directions.

It is an object of the present invention to provide novel materials having attractiveness and utility wherein a wide range of color and other effects are obtainable through means providing controlled interference of components of light.

Another object of the invention is to provide textile materials such as filaments, yarns, fabrics or the like wherein a wide and novel range of color and other effects may be obtained.

A further object of the invention is to provide components adapted to the production of interference colors and other effects either through their combination in bodies such as filaments or the like or in fabrics, or in both.

Still another object of the invention is to provide materials such as bodies, areas, filaments and fabrics or the like wherein light-polarizing and anisotropic or optically active components are combined in a predetermined manner for providing interference colors and other effects.

A still further object of the invention is to provide novel light-modifying bodies capable of contributing to or providing, of themselves, interference colors and other effects.

Another object of the invention is to provide light-modifying components of the character described which are generally adapted to employment in textile materials or the like.

A further object of the invention is to provide materials and components of the character described which may readily be manufactured at reasonable cost and which may have wide esthetic and utilitarian appeal and, accordingly, many new and significant uses.

Still another object of the invention is to provide materials of the charatcer described which are capable of producing interference colors and other effects through portions thereof enabling either transmittal or reflection of light, or both.

A still further object of the invention is to provide novel light-polarizing and birefringent ma.-

terials, and components of the same, which possess new and useful properties.

Another object of the invention is to provide novel materials and components of the character described which are capable of producing variable interference colors and other effects.

A further object of the invention is to provide various means for producing products of the invention.

Still another object of the invention is to provide general improvements in the construction of textile materials such as filaments, yarns, fabrics or the like to the end that appearance of such materials may be enhanced.

These and other objects of the invention will be apparent from the following description taken in connection with the accompanying drawings wherein like reference characters refer to like parts throughout the several views of which:

Figures 1 through 11 are side elevation views of different light-modifying bodies or filaments of the invention;

Fig. 12 is a perspective view of a light-modifying body or filament of the invention;

Fig. 13 is a perspective view of another lightmodifying body or filament of the invention;

Fig. 14 is a cross-sectional view of various forms of light-modifying bodies or filaments of the invention;

Figs. 15 through 17 are perspective views of various other light-modifying bodies or filaments of the invention;

Figs. 18 through 24 are cross-sectional views of various other light-modifying bodies or filaments of the invention;

Fig. 25 is a side elevation View of another lightmodifying body or filament of the invention;

Fig. 26 is a side elevation view, partly in crosssection and with parts broken away, of a lightmodifying body or filament of the invention which illustrates the direction or directions of a light ray relative thereto;

Figs. 2'7 through 30 are perspective views of various swatches of light-modifying fabrics of the invention;

Figs. 31 and 32 are cross-sectional views of light-modifying materials of the invention com prising combinations of film and other components;

Figs. 33 and 34 are perspective views of lightmodifying fabrics of the invention which are, respectively, laminated to a curved or spherical surface and embedded in a molded product;

Fig. 35 is a diagrammatic representation of apparatus for producing a product of the invention;

Fig. 36 is a diagrammatic repersentation of a modification of elements of Figs. 35 and 38;

Fig. 3'7 is a diagrammatic representation of a modification of elements of Fig. 35; and

Figs. 38 through are diagrammatic representations of various apparatus for producing products of the invention.

For a fuller understanding of the constructions of the present invention and their function, a preliminary consideration of certain of the basic optics involved is presented herein, with particular reference to the coacting properties of a plurality of light-polarizing elements; to the cooperation of birefringent and light-polarizing components; and to the interrelation of rotatory polarizing or optically active elements or substances and other light-polarizing means. It is intended that the theory or examples presented in conjunction therewith,

which must necessarily be limited, shall not be regarded as in any sense defining the scope of the invention, said theory and examples being merely for the purposes of illustration and for furthering an understanding of operation of constructions of the invention, presently to be described.

As one example related to the invention, let it be assumed that a pair of light-polarizing elements such as a pair of Nicol prisms or dichroic foils is arranged in optical alignment and that one of said elements may be rotated with respect to the other, the pair constituting a polarizer anl an analyzer. It is well known that when the vibration directions (vibration planes, polarizing directions or axes) of such elements are crossed at right angles, components of light transmitted by the polarizer are removed or extinguished by the analyzer, and that when the vibration directions of both elements are otherwise mutually disposed as, for example, parallel, components of light are transmitted by both elements, varying degrees of transmittal being obtainable between said parallel and crossed positions. Let it next be assumed that a birefringent component such as a crystal, a suitable foil, or the like, is positioned between the polarizer and analyzer, with its crystallographic or optic axis predeterminedly angularly disposed relative to the vibration directions of said polarizer and analyzer. A ray of light passing through the polarizer is plane polarized and thereby enters the birefringent component vibrating in a given direction. Upon entering the birefringent component, it is divided into two rays, an extraordinary ray and an ordinary ray, each of which vibrates in a direction substantially at right angles to the other and traverses the birefringent component with a different index of refraction and velocity, a different distance being traversed thereby and a phase difference being introduced therebetween.

Upon emergence from the birefringent component, both of the rays proceed substantially along a direct path to the analyzer, while continuing to vibrate at right angles. The direction of vibration of the rays depends primarily upon the angular relation existing between the polarizing (vibration) direction of the polarizer and the optic axis of the birefringent component. Upon entering the analyzer, the extraordinary ray may be said to be broken into two components vibrating substantially at right angles, one of which may be considered as an ordinary component which is absorbed or deviated to one side so as to no further be utilized and the other of which is transmitted as an extraordinary component vibrating in a given direction. The ordinary ray, emanating from the birefringent element is resolved by the analyzer into an ordinary component which is absorbed or deviated to render the same no longer functional, and an extraordinary component, vibrating in a direction similar to that of the firstnamed extraordinary component, which is also transmitted by the analyzer.

Thus, it may be said that two extraordinary components are selected and transmitted by the analyzer, vibrating in the same direction but with a phase difference therebetween because one derives from the ordinary ray and the other derives from the extraordinary ray between which a phase difference has been produced. as above described. In consequence, the two extraordinary components are adapted to interfere and the resultant of their interference may be transmitted light of a given intensity, extinction of light, one or more interference colors or other effects depending upon their phase relation or, in other words, depending substantially upon whether reinforcing or destructive interference occurs and to what extent.

The nature of the interference produced may be due to several factors or variables. Bearing in mind that the phase difference depends in general upon the difference between the velocities of the ordinary and extraordinary rays in the birefringent component, and that this difference varies for light of different wave lengths (of different colors) of the spectrum. it will be seen that a resultant interference color, or its diminution or extinction, relates to such variables as the nature of the light source, the retardation properties of the birefringent component, and the relative orientation of the optic axis of the latter with respect to the polarizing axes or directions of the polarizing components. It will be understood that the polarizing axes or vibration directions of polarizing components may have some other angular relation than 90 and may indeed be parallel, provided the optic axis of the birefringent component forms some suitable angle therewith, to produce interference colors.

The relative retardation of the ordinary and extraordinary rays may be altered throughout a wide range where the type of birefringent material employed permits variation of its thickness, where internal structural orientation thereof may be varied, and where the relation between the optic axis thereof and the directions of polarization of the polarizing components may be varied. If a choice of birefringent materials is possible a further variable is provided. Birefringent components of the invention may be varied in all of the above respects.

Where A equals the retardation of one ray with respect to the other (expressed in millimicrons or m where t equals the thickness of the birefringent element or substance; and where m and n2 equal the lesser and greater indices of refraction, respectively, of the two rays emergent from the birefringent element, we have the equation:

A=t(nzn1) The aforesaid two emergent rays have a difference in phase which may be termed P. This dilference equals the retardation divided by the wave length, or

Substituting the equivalent for A, as determined above, it follows that When the retardation is some whole multiple of a wave length, the components of light emerging from the analyzer are equal and opposite in phase and nullify one another. When the retardation consists of half wave length odd multiples, said components of light are equal and on the same side of the line of transmission and, therefore, are of a reinforcing nature. The re sultant equals the sum of the two components and.

the transmitted light is of maximum intensity.

Various birefringent substances or materials are known, some of which are classified as uniaxial and others as biaxial, both being termed anisotropic. In addition, other substances are designated as rotatory polarizing or optically active. The latter substances will also be considered as anisotropic herein, as components of light are rotated in opposite directions thereby and at different velocities. Materials or substances of each category may be employed in products of the invention, the choice depending upon constructional requirements and optical properties desired. Different forms of light polarization such as circular or elliptical polarization will not be treated upon at length herein since, although they occur in various stages of light modification involved in the invention, exhaustive consideration thereof is in no sense essential to an understanding of the optical interrelation of elements or the interference results obtainable.

In general, with other variables constant, it may be said that a. uniaxial birefringent material in conjunction with light-polarizing means permits extinction of light or the obtaining of complementary colors through alteration of the axial relationship of said material and means. while a combination of an optically active substance and polarizing means permits continuous color changes throughout the range of the spec trum by changing the axial relationship therebetween, even though other variables are held constant, the colors being rotated by different amounts. As employed herein, birefringent materials may be considered as substances, components, elements or the like, wherein a phase difference is produced in the general manner described in examples hereinbefore given, and optically active materials may be regarded as substances, elements, components or the like, wherein light is divided into two circularly polarized components thereof, the light vectors of which rotate at different velocities in opposite directions, light of different wave lengths being thus rotated by different amounts, and a resultant vibration plane being provided.

An extensive number of substances and materials are adapted to be employed in forming the bodies, areas, filaments, fabrics or the like of the invention, said substances and materials being of various degrees of suitability according to their properties and according to specific requirements. Among anisotropic materials which may be utilized in forming one or another of the components are the majority of vegetable fibers, animal fibers, mineral fibers and synthetic fibers. other fibers of a generally isotropic nature may also be combined therewith for such purposes as providing a support, an interconnection, an additional optical property or some other function. Among the vegetable fibers contemplated are cotton, flax, sisal and other of the seed hair, bast and structural groups. Animal fibers which may be employed comprise various hairs, furs, wool and silk. The mineral fiber asbestos may also be utilized. Synthetic materials comprising cellulosic, protein and polymer types may be employed to particular advantage and further materials either existing or to be developed, having birefringent, optically active, light-polarizing, fluorescent or other contributory properties may be incorporated in constructions of the invention. Substantially transparent rubber, latex or a synthetic as, for example, Butacite, manufactured by the E. I. du Pont de Nemours Company, Plastics Division, Arlington, New Jersey, maybe employed for special uses involving elasticity, or elasticity combined with variable birefringence. Certain of the above materials may be employed function- Glass and ally of themselves while others may coact to produce various effects or serve as carriers for various functional substances.

wherein filaments and fibers are employed, long continuous types constitute a preferred embodiment as will be apparent from the constructions shown and described, although short staple fibers and small bodies may serve special functions. Thus, synthetic materials of the cellulosic and polymer types may be considered as particularly adapted to employment for forming filament and fabric components of the invention as well as for coatings or the like which may be applied thereto, as will presently be described.

Among the synthetic materials contemplated for various specific uses are viscose and acetate rayons, regenerated cellulose, nitrocellulose, ethyl cellulose, cellulose acetate, vinyl acetate, nylon, vinyl chloride, vinylidene chloride, polyethylene, polyvinyl acetaL polyvinyl alcohol and other materials, said materials being treated or modified as may be required to provide special characteristics. Certain of these materials are known as adapted to be formed into birefringent and light-polarizing elements through various treatments involving their subjection to stretching operations, applications of fields of force, stain. dye. acid and heat treatments or the like. For example, ethyl cellulose, regenerated cellulose, and polyvinyl alcohol may be stretched, under suitable conditions of temperature or in conjunction with softening agents, and preferably set to provide birefringent materials as, for example, to provide a material wherein a high degree of substantially uniform crystalline or molecular orientation is accomplished throughout the material, said material having, generally, an optic axis consistently extending in a predetermined direction.

Various controls may be employed for obtaining predetermined diameters or thicknesses of filaments or other components of the invention. For example, in extrusion processes'it is known that the rate of delivering materials to a spinneret, the rate of drawing materials away therefrom, and the amount of stretch applied thereto may all be controlled to regulate diameters of filaments. If, for example, a filament is drawn to four times its original length, it may be reduced to substantially one-half its original diameter. Certain of the materials may be cold drawn and others may be stretched in a softened condition, as provided by applications of heat or softening agents. Various forms of spinnerets or extrusion orifices relating to diameter and con tour of extruded filaments are well known.

Materials of the above-mentioned type, which may readily be stretched and elongated and thereby have their thicknesses and internal structure oriented as, for example, to acquire a certain birefringence, are adapted to be formed into bodies or filaments, orto be employed as coatings therefor of the type contemplated herein. After such bodies or filaments are formed, they may readily be joined with other components such as light-polarizing bodies or filaments through constructions of the invention to provide a predetermined relation of optic and light-polarizing axes. It will be understood that in addition to providing predetermined characteristics of birefringence in filament components of the invention, such qualities as tensile strength, flexibility, durability, resistance to shrinkage or the like may be varied therein, the stretching process generally improving tensile strength and flexibility and increasing birefringence.

The properties of birefringent materials relating to theobtaining of various predetermined colors will now be considered more specifically, and, for purposes of illustration, one of the aforementioned general types of such materials which may be embodied in constructions of the invention will be utilized. Accordingly, let it be assumed that a plurality of such bodies, as, for example, monofilements or coagulated multifilaments, uniformly stretched (of constant birefringence), but of predeterminedly different thicknesses are arranged in progressive order of thickness, side by side, between any suitable light polarizers crossed at 90. Let it also be assumed that the optic axes of the filaments are all disposed at a predetermined angle relative to the vibration directions of the light polarizers, for example, at 45, that white light is employed and that the filaments and polarizers are fixed as to axial relation.

The relation of retardation, phase difference and wave length has been described hereinbefore. In accordance therewith, the field of view surrounding the filaments will appear dark and, assuming certain thicknesses of the filaments, the thinnest filament may, for example, appear bluegray and other filaments, in order of increased thickness, may appear, respectively, white, yellow, orange, orange-red, deep red, violet, indigo, blue, blue-green, green, et cetera. The relationship between interference colors due to monochromatic light and white light should be considered. If monochromatic light is substituted for the white light source, that filament which is of such thickness as to provide a retardation of A will cause the vibration components to be equal and opposite and cancel one another out, the filament appearing as a dark band. All filaments which provide a retardation which is a whole multiple of x cause a similar operation. Conversely, if the filaments provide retardations at odd multiples of /2 maximum intensity will occur because the vibration components are equal and in the same phase.

Interference colors due to White light are a subtraction of all of the various wave lengths of the spectrum from white. Assuming, in view of the foregoing, that monochromatic light produces dark bands for different thicknesses of hirefringent materials and maximum intensities at intervals intermediate thereof, the difference between the wave lengths at the opposite ends of the spectrum is such that the first dark band for violet occurs almost in the first position of maximum intensity for red. For violet, the band is approximately 410 m As the wave length for red is approximately 700 m the maximum intensity for red occurs at 350 m or 7\. When the thickness and double refraction provide a retardation of 410 m no violet is present in the interference color. Since the maximum intensity for red occurs at or 350 m the percentage intensity at 410 m would be:

X l= 83 percent )\r tropic substance wherein orientation, as obtained for example through stretch, is held uniform. If this constant is substituted in the equation a straight line curve is the result in an interference color chart. If various thicknesses are assumed, the corresponding retardation A may be determined directly. If the normal sequence of colors is known, it is possible either to predict the color of the substance of a given thickness or to ascertain the thickness of the substance having a given interference color, provided the axial relation of the substance is such that 1Z2n1 is a maximum.

In an interference color chart, interference colors with A less than 550 m are said to belong to the first order. Violet (A=550 m belongs at the boundary of the first order. From violet A=550 m l to violet A=1128 m the colors belong to the second order. From violet A=1128 m, to violet A=1652 m the colors belong to the third order. Above the fourth order, colors are not easily separated. The colors at the end of the first order and at the beginning of the second order are the most striking and brilliant. At the end of the fourth order they merge into one another, forming tints of green and pink tending toward grayish white. These colors are distinct from the blue gray, white and yellowish white of the lower first order. Identification of the order of a given color may be determined by using a mica plate or the like capable of increasing or decreasing retardation of an area by about A A (sodium light). Such an increase or decrease in the lower first or second orders produces a set of colors entirely different from that occasioned by a similar change in higher orders. For example, in the case of a first-order yellow A= l00 In an increase of 175 my. will result in violet A=575 m and a decrease of the same amount will produce white A=225 m l. The same increase or decrease in retardation above the fourth order would produce little perceptible change.

It will be understood that stretching of a filament of the type considered herein, or micellular orientation as obtained through extrusion of a filament from a die or orifice, or both, may be employed to provide a filament having a predetermined birefringence. It will further be understood that increases in stretch produce increases of birefringence and decreases in thickness, said increases of birefringence generally exceeding accompanying decreases in thickness so that resultant increases in retardation properties of the filament occur and the interference colors capable of being produced when the filament is positioned between crossed polarizers may commence in the first order and proceed through second and third orders, et cetera. The exact characteristics for any material may readily be ascertained and the birefringence and retardation properties thereof be charted. For example, a filament of polyvinyl alcohol of .003" thickness may be stretched and set under suitable conditions of heat so as to acquire a birefringence of approximately 0.013 and a reduced thickness of approximately .002". When formed into a composite structure such as that shown in Fig. 3, namely, when positioned between light-polarizing components so that a principal axis of the birefringent filament is disposed at 45 relative to polarizing directions crossed at a second order blue may be provided. A second filament of similar initial thickness may be stretched to acquire a birefringence of approximately 0.029 and a reduced thickness of approximately .0015" and, when similarly employed with polarizing components, may provide a second order reddishpurple. Lesser and greater stretches of said filament could be employed to provide, respectively, first or third and higher order interference colors. The interference color obtained through a given amount of stretching depends upon the hirefringence per unit thickness produced in a given material and, accordingly, different materials may be differently elongated to obtain a given interference color.

Light-polarizing components of the nature contemplated herein may be of any type having properties which contribute satisfactorily to the functional qualities required thereof in a given construction of the invention. Such qualitie involve the production of colors and other effects and the adaptability of the constructions to be employed in or to constitute products of the type contemplated as, for example, a filament, fabric or other area of material. Several known lightpolarizing treatments or substances, such as those identified with various synthetic plastic materials may appropriately be employed or modified for use in forming light-polarizing components or portions of structures of the invention. A list of such light-polarizing materials is presented hereinafter. Presently-known polarizing materials are suitable for employment in constructions of the invention but it is also considered that the invention comprehends the development of other polarizing materials insofar as they are employed in similar constructions or serve in similar functional capacities.

Polarizing components of the type comprehended herein are considered as possessing such light-polarizing characteristics or properties that they are capable of coacting to produce interference colors or the like when employed with substantially any birefringent or optically active component or substance having retardation or other properties adapted to coact with polarizing means for producing perceptible interference colors orthe like. Thus the weakest partial polarizing means which can be employed may be said to be that which, when crossed at 90, is capable of coacting with a birefringent or optically active substance or component to produce a perceptible color or colors substantially at the end of the first order and at the beginning of the second order of spectra. The strongest or most complete type of polarizing means which may so be employed is that which, when polarizing axes thereof are crossed at 90, produces extinction of light. The most complete type of polarizer, when employed with anisotropic materials, is particularly adapted to provide the most brilliant interference colors. Partial polarizers and polarizers providing more than 99% extinction, formed of synthetic plastic materials are well known. Thus effective lightpolarizing substances and components of the type contemplated herein may be considered as comprising a range extending from a relatively weak partial polarizer which transmits components of light vibrating in a plurality of directions, although preferentially in a given direction, to a polarizer which may substantially absorb all components of light excepting those vibrating in a given direction. It will be apparent that polarizers intermediate of said extremes may be employed. The well-known Judd unit of color difference may be employed in determining the weakest perceptible color obtainable with a partial polarizer, as above described, and may also be used in determining different interference colors produced.

While, in general, the more completely lightpolarizing components may constitute a preferred embodiment, certain constructions of the invention may advantageously employ so-called partially light-polarizing components or a plurality of such partially light-polarizing components in superposed or optically aligned relation to provide more fully light-polarizing components. It is believed that certain light-polarizing aspects of the invention are such as to involve novel processes and products which will presently be described. It will be understood that partial polarizers may be employed to provide dilute colors through their property of transmitting unpolarized as well as polarized components of light. In general, it may be said that polarizing components of the invention are of types possessing such light-polarizing properties, form and arrangement in the constructions as to contribute effectively to the production of interference colors and other efiects of acceptable quality relative to the uses intended.

Light-polarizing components of the type contemplated herein may appropriately be formed of substances providing a neutral polarization of light, that is, they may polarize light substantially impartially throughout the spectrum of, for example, white light, or they may be formed of substances providing light-polarization throughout a predetermined restricted band or bands of Wave lengths. It is contemplated that certain of the light-polarizing components may employ light-polarizing, or light polarizing and other substances, enabling their transmittal of polarized light predominantly of certain wave lengths. For example, a polarizing treatment may provide a red, a blue or some other color in the polarizing component whereby the polarizer transmits vibrations of said color preferentially. Or, some tint, dye or the like may be added to the polarizing component or be provided in a coating or in another component associated therewith to provide a predominant color characteristic in a light-modifying body or filament of the invention. Where coacting light-polarizing and birefringent or optically active components are employed for producing interference colors of given characteristics, said provision of a dye, tint or the like may be utilized to provide,

in effect, a blend with interference colors or a I reinforcement of the same. Where said coacting light-polarizing and anisotropic components produce substantially white light said provision of a dye, tint or the like may be utilized for providing a dominant color while the interference resultant is employed for producing a high luster effect. It will be understood that fabrics or other materials comprising polarizing components and such tints or dyes may be formed so that light emanating therefrom will predominantly be colored light as provided by said tints or dyes. It is further to be understood that fabrics or other materials comprising polarizing and birefringent or optically active components and such tints or dyes may be formed so that light emanating therefrom will predominantly be colored light as provided by said tints or dyes, or some blend thereof with interference colors, if so desired.

Referring to the drawings, Fig. 1 illustrates a composite light-modifying body l2, such as a fragmentary portion of a composite filament comprising a light-polarizing core component l4, of any suitable cross-sectional shape as, for example substantially cylindrical, having a direction of polarization or vibration direction generally indicated by double-headed arrow 16, and a Z twist or spiral of one or more birefringent filament components [8, of a suitable cross-sectional shape, such as substantially round or fiat, formed around the core. It may be assumed that the structural orientation of the birefringent filament components I8 is substantially longitudinal of said components and that the direction or plane of a principal axis of said filament components forms a predetermined angle with said polarizing direction l6 of the core as, for example, an angle of 45.

It will be noted that the thickness of core 14 is appreciably greater than that of each filament l8, and, accordingly, because filaments l8 provide a relatively thin layer around the core, a functional superposition of birefringent twist and light-polarizing core is presented substantially throughout the composite body when it is viewed from any position radially thereof. It is to be assumed that core I6 is of a predetermined diameter and has predetermined light-polarizing properties. It is also to be understood that birefringent components 18 have predetermined diameters and preferably similar internal structural orientation and are of such thickness as to provide a predetermined retardation and phase difference between ordinary and extraordinary rays transmitted thereby.

Wherever a twist of components is shown herein, the number and thickness of said components are contingent upon the relative thickness of the core and the angle at which the twist is to be wound around the core. Unless otherwise specified, either an S or a Z twist may be employed. Light incident twist [8 passes through the same to core M. It is plane polarized by core 14 and the transmitted components again enter twist l8, at a side remote from the area of incidence, and a difference of index of refraction between said components occurs in the manner hereinbefore described. Composite filament i2 is adapted to be employed with other filaments of similar or other characteristics in an assembly such as a fabric. In said fabric, filament [2 may serve as a cooperative or coacting body with another light-polarizing means in the production of interference colors or other effects. Core component [4 may appropriately be formed as a monofilament or a multifilament of extruded, coagulated substantially parallel strands of a suitable synthetic plastic material which has been treated to serve as a light polarizer.

Filament components l8 may be formed of any suitable birefringent material such as one of the materials hereinbefore described. It is to be assumed that the materials employed in composite body or filament l2 and in all of the constructions herein are suitably treated to provide satisfactory characteristics of tensile strength, resistance to shrinkage and other qualities which may be required of a fabric or other area of material of a type contemplated.

Fig. 2 represents a composite filament 20 of the same general type as that of Fig. 1 comprising core component 22, having a light-polarizing axis or direction 24 and an external layer of birefringent filament components 26. Composite filament 20 differs from filament l2, however, in

14 I that birefringent layer 26 is formed of an S twist. The composite filaments of Figs. 1 and 2 may advantageously be combined in a fabric as, for example, one filament serving as the warp and the other as the weft or filling, said arrangement enabling, for instance, crossed polarizing components and parallel birefringent components, as provided by said warp and filling. It will thus be seen that filaments of the warp and filling coact to produce interference colors or the like.

Fig. 3 shows a composite light-modifying body or filament 28 comprising a birefringent core com ponent 30 formed of one or a plurality of coagulated filaments of the type hereinbefore described, the structural orientation of said core preferably being substantially longitudinal thereof and a predetermined generally uniform direction of the optic axis thus being established throughout said core component. A twist or spiral of one or more light-polarizing filament components 32, having a direction of polarization or vibration direction in dicated by double-headed arrow 34, is formed around core component 30. Core 30 may preferably be substantially cylindrical in shape and twist components 32 may preferably be generally cylindrical or fiat in shape although other shapes may be employed. It will again be observed that core component 30 is of considerably greater diameter than twist components 32 and thus provides a superposed functional relation of components when viewed from any position generally radially of the core. The angle at which twist components 32 are formed around core 30 provides a predetermined angular relation between polarizing direction 34 and the optic axis of core component 30. It may be assumed that core 33 comprises a predetermined thickness of birefringent material contributing to a given retardation and phase difference between transmitted light components. From a radial viewing position and looking through composite filament 28, it will be apparent that portions of polarizing twist 32 which are located generally diametrically opposite one another, on opposite sides of the core, are crossed at angles depending upon the angle of twist, and that when crossed at as generally indicated in Fig. 3, one of the preferred angular relationships therebetween exists. It will further be apparent that a birefringent component is provided in the form of core 30 havin its internal orientation, and accordingly its optic axis, angularly disposed relative to said crossed polarizing directions, said angular relation being generally indicated as 45, which constitutes one of the preferred angular relationships between the optic axis and polarizing axes. Light rays incident any given surface portion of twist 32 are plane polarized in passing through the same, are resolved into ordinary and extraordinary rays having a phase difference by core 30, and are transformed into componentsvibrating in a given plane by the opposite portion of twist 32 whereby an interference color is produced. Composite body or filament 28, accordingly, is a self-sufiicient unit for producing interference colors and other effects and may be employed in a fabric as, for example, the warp, substantially conventional transparent filaments being suitably employed as filling or vice versa.

Fig. 4 illustrates a composite light-modifying body or filament 36 having a twist of substantially fiat, ribbon-like components 33 formed around a core component 40. The twist may consist of light-polarizing components and the core comprise a birefringent component, or the twist may be formed of birefringent components and the core consist of a light-polarizing component. Composite filament 36 may thus function either in the manner of the filaments of Figs. 1 and 2, or similarly to that of Fig. 3. It will be apparent that use of ribbon-like component 38 permits a decrease in the angle of twist without a proportional increase in the diameter of filament 36. If desired, the twist could be overlapped to provide different thicknesses of a birefringent layer.

In Fig. 5, a composite light-modifying body or filament 42 which may be altered dimensionally to vary interference colors or the like is shown. As a preferred embodiment, composite filament 42 may be regarded as generally similar to that of Fig. 3 as to the relation of components, with a twist of light-polarizing filament components 44 having vibration, directions 46 formed around a birefringent core component 48. However, core component 48 is formed of a suitable elastic material, such as a transparent rubber, latex or a synthetic elastic material of the type above-described so that, upon stretching said core component as indicated by the arrows, its thickness may be altered and different retardation properties may, accordingly, be acquired thereby. In a modified form, core 48 could serve as an elastic light-polarizing component and twist 44 could be in the form of elastic birefringent components, preferably bonded to the core whereby, upon stretching filament 42, and thus probably rendering the core slightly less efficient as a polarizer, twist 44 would be stretched obliquely with respect to its axis and both thickness and direction of internal orientation thereof would be altered, thus afiecting its properties relating to the production of interference colors as hereinbefore described. In a less preferred modification of the first-named elastic embodiment, the twist may also be bonded to the core, provided a suitable elastic polarizing material is used. The firstnamed embodiment, which is preferred, provides a self-sufficient unit for variably producing interference colors and, accordingly, it may be combined with substantially transparent conventional elastic or essentially nonelastic filaments to form a stretchable fabric wherein the color and light transmission may be varied by stretching and relaxing the same. The second-named or less preferred embodiment would require combination with another light-polarizing means.

The composite body or filament 50 of Fig. 6 may be considered as illustrating any of the lightmodifying bodies of Figs. 1 through with an additional layer or twist formed thereabout. For example, it may consist of a birefringent core component 52, a twist of light-polarizing filament components 54 having a polarizing direction 56 formed around the core, and a twist of substantially transparent surfacing components 58 formed around components 54. Surfacing twist 58 may, for example, be colorless and contribute to an appearance of whiteness of a fabric in which the filaments are woven when light is reflected from the fabric. Or, twist 58 may comprise a transparent dye or tint for providing reflection of colored light and for coacting with core 52 and twist 54 so that interference colors produced by the latter will be modified by the color of twist 58 and a different resultant color will be obtained. Where core 52 and twist 54 produce a substantially white interference color, twist 58 may be employed to provide some other color which is dominant. Twist 58 may also be utilized to fur- 16 nish a desired surface texture and, accordingly, may be twisted more irregularly than shown. Furthermore, twist 58 may be of a material adapted to receive a desired surfacing treatment which, for example, may be applied to a fabric in which the filament is incorporated.

Twist layers 54 and 58 may, however, each consist of partial polarizers, preferably superposed so that their polarizing directions extend similarly, the two layers reinforcing one another to provide more complete polarization of light. If twist components 54 and 58, as partial polarizers, serve said curnulative function, it will be apparent that certain materials which are capable of producing only partial polarization of light but which have other advantages such as availability, low cost and adaptability to textile uses may be employed for the purpose. If, alternatively, composite body or filament is considered as comprising a light-polarizing core 52 and a birefringent layer or twist 54 formed therearound such as shown in Figs. 1 or 4, doubleheaded arrow 56 may be regarded as a direction of internal orientation of the birefringent layer and external twist 58 may be considered as a surfacing layer of the general type above described, and either isotropic or predeterminedly anisotropic for providing some desired retardation in conjunction with birefringent layer 54. In constructions of the invention involving twists, spins, plies, braids or the like, bonding or fusing of inner superposed surface portions of the components may be desirable to reduce a loss of transmitted light by reflection at said inner surfaces.

Fig. '7 shows a composite light-modifying body or filament 60 having a core component 62, an S twist 64 formed around the core, and a Z twist 65 formed around twist 64. Filament may comprise at least any of the constructions described rclative to Fig. 6 and illustrates an external reverse twist 56 formed on an underlying twist. Certain structural advantages of combinations of s and Z twists are well known in the textile art. In addition, it will be seen that different angles of twist of layers 64 and 66 may be used for different interference effects if said layers are both birefringent. Double-headed arrow 68 may be regarded as indicating either a polarizing direction of a light-polarizing layer or a direction of internal orientation of a birefringent layer, according to the interpretation of the construction.

Fig. 8 represents a light-modifying body or filament 18 comprising components 12 and 14 which are twisted together. Component 12 may suitably have light-polarizing properties, a po-- larizing direction thereof being indicated by double-headed arrow 16, and component 14 may be composed of a suitable birefringent material having a predetermined optic axis. The angle at which said components are twisted together is predetermined as, for example at 45. superposed portions of the components provide a combination of light-polarizing and birefringent materials such that filament 10 may be employed in a fabric, in conjunction with other polarizing means, to produce interference colors. Fig. 8 may also be considered as representing a ply of filaments as, for example a ply of any of the filaments described herein with a preferably transparent filament whereby the desirable features of a ply construction which are known in the textile art may be achieved. It will be understood, however, that where the light-modifying filament of said ply is of a type for coacting with another light-modifying filament in a fabric (1. e. warp and filling) that an oblique orientation of said ply filament exists which must be considered with respect to the orientation of the coacting filament. Fig. 8 could also advantageously represent a ply wherein both of the filaments comprise a polarizing core and at least one of the filaments comprises a birefrigent covering as, for example, 2. ply of the filament of Figs. 1 and 2. Said ply would provide a self-sufficient structure for producing interference colors.

Fig. 9 illustrates a fragment of an orientable body 18, suitable for conversion into an oriented body portion 18 which may be employed as, or, in turn, converted into a birefringent component or a light-polarizing component or entity. Body portions 18 and 18 may, for example, be in the form of a substantially flat ribbon or strip, or a substantially round or other form of filament. Said portions may, appropriately, be composed of a suitable plastic material such as polyvinyl alcohol, regenerated cellulose or some other material of the type hereinbefore described. Body portion 18 may be considered as in a generally unoriented condition or to be partially oriented as, for example, in a direction longitudinally of its long axis. To achieve a modified orientation in portion 18, body portion 18 is twisted at a predetermined angle with respect to its long axis, and is then stretched longitudinally under suitable conditions of environment, preferably while undergoing movement in the direction of arrow 80, stretch occurring in a predetermined twisted or folded portion thereof generally represented as between a and a. Said stretching of the twisted portion provides an overall orientation therein substantially in the direction of double-headed arrow 82. After leaving the zone a, a, wherein the stretching occurs, the body is untwisted or unfolded and the untwisted portion 18' possesses an oblique orientation in a direction such as that represented by double-headed arrow 84. It will be apparent that the direction 84 is primarily de pendent upon the angle at which body 18 is twisted or folded although other factors may be involved.

Two or more bodies of the type of body 18 may be twisted together and a similar procedure to that above described may be utilized to provide oblique orientation therein, it being apparent that the method of stretch employed should be such as not to permanently bond the bodies together. Body portion 18' may subsequently be treated as, for example, while held taut, to remove any fold marks therein. Furthermore, assuming the above-described stretch of the material to have been less than said material is adapted to undergo, a further longitudinal stretch may be applied to portion 18 without appreciably disrupting the oblique structural orientation therein, it being apparent that the primary oblique orientation is well established in the material. Treatments of heat or other suitable softening agents may be applied to the material in conjunction with the above-described methods to facilitate the same. Subsequent treatments for hardening, insolubilizing, coating or otherwise treating the material may be applied thereto such as applications of heat, boric acid or coatings hereinafter described.

In its condition of oblique orientation, body 18 may be employed in any of various capacities where a birefringent material having said blique orientation would prove useful. For example, it may be utilized as a birefringent component in various of the constructions described herein. Assuming body 18 to have such composition or characteristics that when it is stretched it acquires light-polarizing properties, or may subsequently be treated to acquire said properties, it will be seen that a polarizing body having a predetermined oblique light-polarizing direction may thus be formed. In the form of a polarizer, body 18 may also be employed as a polarizing component of the present invention having oblique orientation of its polarizing direction. It will be evident that the plurality of oblique orientation angles which may be provided in birefringent and polarizing components, as above described, when added to longitudinal directions of orientation obtainable by known methods of stretch or other processes, and reverse directions of twist hereinbefore described, offer substantially any relative disposition of optic axes and light-polarizing directions. Other constructions and methods relating to orientation of components will also be described herein. It is to be understood that the above language relative to twisting body 18 is also intended to cover the coiling, folding, spinning or otherwise shaping of the same to achieve a substantially similar arrangement thereof during the stretching process. Alternatively, said twisting or the like may be performed, simultaneously within the portion undergoing stretch.

Fig. 10 illustrates a light-modifying body 86 comprising a twist of light-polarizing components 88 formed around a birefringent core component 90. While said twist is shown as composed of generally flat, ribbon-like components, said components may be substantially round or of some other shape. Fig. 10 is primarily intended to illustrate a possible relation of various axes which may exist in a body or filament of the invention. For example, diametrically opposed light-polarizing portions are shown as having polarizing directions 92 and 94 which are crossed at with respect to one another. Birefringent core component 90 is represented as having a direction of structural orientation 96 and principal axes 98 and I00 which are disposed substantially at 45 with respect to the polarizing directions 92 and 94.

Fig. 11 illustrates a light-modifying body I02 comprising a plurality of braided components I04, I06, and I08, any two of which may appropriate1y be formed of a light-polarizing core having a layer of oriented birefringent material formed thereabout. The third of said component may suitably have merely light-polarizing properties although a birefringent layer of predetermined orientation could also be formed thereupon. Assuming but two birefringent layers, as above described, one of said layers would appropriately be of an 8 type and the other of a Z type. The double-headed arrows H0, H2 and H4 indicate the polarizing directions of said components I04, I06 and I08. Accordingly, braided body I02 comprises a plurality of superposed functional light-polarizing and birefringent areas for producing interference colors wherein are comprised light-polarizing portions and interposed birefringent portions of alternately different thickness having suitable axial directions for coacting with one another. In accordance with the abovedescribed construction, the principal axes of superposed birefringent portions may extend in a similar direction. As shown in Fig, 9 and presently to b amplified, birefringent components having a different relation therebetween may be employed. Where the third component also has a birefringent layer formed thereabout, it will be apparent that the above-described alternately different thickness of interposed birefringent portions may not necessarily exist. The construction of Fig. 11 may also be employed for other obvious purposes as, for example, whenever it is desired to provide an angular relation of one or more components with respect to the longitudinal direction of a body.

Fig. 12 shows a light-modifying component II6 which is adapted to polarize light passing therethrough and which may have a light-polarizing direction H8 or some other light-polarizing direction or directions. Component I I6 is adapted to polarize light which passes therethrough, substantially impartially in any direction. The component I I6 may be formed of a suitable transparent material I20 having portions I22 adjacent the surface thereof which may be rendered light-polarizing by any suitable means, or I20 may represent a substantially isotropic core material or a non-functionally oriented material which is not adapted to be rendered light polarizing and I22 may represent a light-polarizing layer formed around said core. Polarizing portion or layer I22 may appropriately be composed of a partial polarizer whereby light passing through component IIG may be polarized to a desired degree by passing through substantially opposite areas of layer I22 and be d ubly D tially polarized to achieve a more complete polarization. If deisred, portion I20 may be lightpolarizing throughout, it being obvious that physically thicker synthetic polarizers should, in

.generaLlhave less density to equal the performance of thinner polarizers.

In another construction relating to Fig. 12 component IIB may comprise a light-polarizing portion having a direction of polarization extending differently from that of double-headed arrow II8 as, for example, portion I20 may be formed as described relative to Fig. 9 and any predetermined oblique orientation may be provided therein. In said construction, portion I22 may represent either a polarizing portion of I20 adjacent the surface or a protective coating for an underlying polarizing portion. It is to be understood that a protective coating may be applied to a surface of any of the components described herein or to layers formed thereupon.

In another modification of Fig. 12, component H6 may comprise an isotropic or a non-functionally oriented transparent core I20 and a lightpolarizing coating I22 formed around only a part of its circumference as, for example to one side of dotted lines D, b, said partial coating being provided after incorporation of component I I6 in a fabric, as will presently be described. In still another modification, component II6 may comprise an isotropic or non-functionally oriented core I20 and a layer I22 composed of an optically active substance comprising, for example, suitable oriented minute crystals of a rotatory, polarizing type, for example, sulphate of strychnia, sulphate of aethylendiamin, sodium chlorate, or a suitable rotatory polarizing amorphous solid such as may be formed from an optically active solution, for example, tartaric acid. An additional protective coating (not shown) or a stabilizing treatment of the optically active layer I22 would probably be required in the lastnamed modification. Although component H6 is represented as of cylindrical shape, it may have some other shape, as hereinbefore described. Light-polarizing properties of component I I6 may 20 be provided by any of the well known methods involving stretching, applying predetermined fields of force thereto, rubbing, treating with a stain, a gas or an acid, applying heat thereto, or by some other method.

Fig. 13 illustrates a light-modifying component I24 which is adapted to serve in a birefringent capacity and which may comprise a birefringent core I26 and a protective coating I28 or a substantially isotropic core I25 and a birefringent coating l28. The last-named form would permit a relatively thin birefringent portion relative to the overall thickness of the component. Many suitable birefringent materials would, however, permit their use as filament components without a protective coating thereon. Although component I24 is represented as round in crosssection, it could be of some other shape as, previously described. A birefringent component could also be formed as a hollow rod or tube to reduce the thickness of the material while providing a relatively large outside diameter, said thickness contributing to a predetermined phase difference between transmitted components of light when employed with polarizing means.

Fig. 14 illustrates a plurality of cross-sectional shapes in which various constructions of the invention, such as light-polarizing and birefringent components, may be formed. Choice of the same depends upon the interference effects and other characteristics desired in the fabric or other material. Type 4 constitutes a preferred embodiment for general use in the constructions described herein because it is radially uniform and provides consistency, as between components, of one of the variables, namely, that of thickness which relates to the production of interference colors. Type 5 has already been described as particularly adapted to use as a form of twist. Other forms may be employed where a predetermined selection of other variables, hereinbefore described, permits slight alterations of thickness of birefringent components without appreciably varying the interference colors produced. Where functional components are in the form of coatings, it will be understood that said coatings may be substantially uniformly distributed over irregular or other carriers therefor such as types I, 2 and 3. Similar considerations are pertinent relative to polarizing components. Forms of components represented by types I, 2 and 3 may also be employed where unevenness of interference effects and/or texture are desired. It will be understood that shapes other than those shown may also be employed.

Figs. 15, 16 and 17 illustrate various forms of composite light-modifying bodies or filaments comprising core components and surrounding layers coated thereupon. Subcoats therefor may also be employed, as required. Functionally, said bodies are substantially similar to bodies and filaments previously described, having a twist formed around a core.

In Fig. 15, a composite light-modifying body or filament I30 is shown comprising a core component I32 and a coating component I34 surrounding said core. Core I32 may appropriately represent a light-polarizing component having a predetermined polarizing direction such as I36, and coating I34 may be formed of a suitable birefringent or optically active material having a predetermined direction of orientation such as I38 which provides a suitable angular relation of its principal axis relative to polarizing direction I36, or, if preferred, comprising a random disposition of birefringent r optically active particles. The oblique direction I36 may be obtained as through employment of a light-polarizing element of the type described with respect to Fig. 9 as a core, or by a method presently to be described. Coating I34 may then be applied and orientation thereof achieved by stretching the composite body or by applying a field of force to said coating as, for example, while applying the coating or thereafter. The functional optical relation of polarizing and birefringent components having a relative disposition of their axes similar to that above-described has been described hereinbefore. Accordingly, body or filament I30 may be employed in conjunction with a similar filament, as in a fabric, whereby said filaments are capable of coacting to produce interference colors. Or, body or filament I30 may be employed with any suitable polarizing means for providing interference colors.

Filament I30 of Fig. 15 may also represent a light-polarizing layer I34 having a polarizing direction I38 surrounding a birefringent core I32 having a direction of orientation I36. Light, in passing through the filament is intercepted by two polarizing portions having parallel directions of polarization and by a birefringent portion having an optic axis angularly disposed relative thereto, interposed between the polarizing portions, an arrangement adapted to produce interference colors. Alternatively, core I32 may comprise optically active rather than birefringent properties.

In Fig. 16, a composite light-modifying body or filament I40 comprising a core component I42 and a coating component I44 surrounding said core is shown. Core I42 may comprise a lightpolarizing material having a polarizing direction I46 and coating I44 may suitably be formed of a birefringent material having a direction of orientation I48, or, alternatively, coating I44 may comprise an optically active material. As a modification, core I42 may comprise a birefringent material having a direction of orientation I46 and coating I44 may comprise a spirally oriented coating having a polarizing direction I 48. As described relative to a twist, a spiral orientation formed around a core provides crossed polarizing axes transversely of the core. The significance of said arrangement of components relative to production of interference colors has been described hereinbefore.

Fig. 17 shows a composite light-modifying body or filament I50 comprising a core component I52, a coating component I54 surrounding said core, a second coating component I56 surrounding coating I54, and a third coating component I58 surrounding coating I56. Core I52 comprises light-polarizing material having a polarizing direction such as I60. Coating I54 comprises an optically active substance which is preferably predeterminedly oriented with respect to polarizing direction I60, but which may consist of areas or particles disposed at random. Coating I56 comprises light-polarizing material having a polarizing direction I62, and coating I58 represents a protective surfacing material. Composite filament I50 is adapted, of itself, to produce interference colors in a manner hereinbefore described. Filaments of Figs. 15, 16 and 17 could comprise both cores and coatings which are elastic to produce effects generally similar to those described with respect to Fig. 5.

Fig. 18 represents, in cross-section, a composite light-modifying body I64 of substantially flat or 22 ribbon-like form comprising a light-polarizing layer I66 having a predetermined polarizing direction, and a superposed layer I68 formed thereupon or bonded thereto comprising an optically active substance. At least portions of the optically active substance are so oriented with respect to said polarizing direction as to coact with light-polarizing layer I66 and to rotate components of plane polarized light entering the optically active substance from the polarizing layer. Plane polarized light incident layer I68 from an external source (not shown) may be rotatorily polarized by the optically active substance and resolved into interference colors by polarizing layer I66.

Fig. 19 illustrates, in cross section, a composite light-modifying body I10 of substantially fiat or ribbon-like form comprising a light transmitting layer or core I12 and a surrounding layer or coating I14. Core I12 may comprise an optically active substance and coating I14 may comprise a light-polarizing material having a predetermined light-polarizing direction. At least portions of said substance are so oriented with respect to said polarizing direction as to coact with the light-polarizing material and to rotate components of plane polarized light entering core I12 from coating I14. In turn, a substantially opposite portion of coating I14 serves as an analyzer for the rotated components to provide interference colors. Alternatively, core I12 may comprise light-polarizing material and coating I14 may comprise an optically active substance, the optical properties of such a construction being similar to those of Fig. 18 excepting that rotatory polarization occurs for light passing through the body from a source either above or below the same, as positioned in the drawing.

Fig. 20 shows, in cross-section, a composite light-modifying body I16 of substantially fiat or ribbon-like form comprising three functional layers I18, I and I 82. Said layers may be effectively bonded to one another or may consist of a central layer I80 having coatings I18 and I82 applied to both sides, or a central layer I80 having a coating I18 applied to one side and a layer I82 bonded to the other side. The central layer may comprise light-polarizing material and the superposed layers may, accordingly, comprise an optically active substance or substances or, alternatively, the central layer may comprise an optically active substance and the superposed layers may, accordingly, comprise light-polarizing material. At least portions of the optically active substance are so oriented with respect to a polarizing direction of the polarizing material as to produce interference colors. The optical properties of the two constructions are generally similar to those of Fig. 19.

Fig. 21 illustrates, in cross-section, a twist of transparent filament components I84 bonded to a transparent core I86 by a transparent bonding substance I88 such as vinyl acetate or methyl methacrylate. The bondin substance I88 may serve several functions. For example, it may be adapted to prevent slippage of the layer of filaments around the core during a twisting process and/or after incorporation in a fabric. Or, it may serve as a barrier to prevent a dye, stain or the like, from penetrating to underlying portions of the filaments I84 or to the surface of core I86. The first-named function applies to any of the twist constructions shown herein, and the second-named function would apply when twist I84 is a light-polarizing component. A twist adapted to be treated to become light-polarizing could thus be stained, dyed or the like upon exposed portions only, thereby reducing the polarizing portions through which light would pass. A slight diffusing property of bonding substance I88 could be provided therein, in special instances where a small diffusion of interference colors is desired. Relative to the general subject of selectively treating certain components of composite products of the invention with a dichroic fluid, a conventional dye or another substance, the construction of Fig. 21 serving as an example, it will be understood that twist I84 could be fused, coagulated or otherwise bonded to core I86, or that said core could, for example, be of a material nonreceptive to the fluid, or selectively receptive to the dye, et cetera.

Fig. 22 illustrates, in cross-section, the employment of a suitable transparent subcoat I63 between surfaces of a composite light-modifying body of the invention as, for example, between a core I92 and a coating I94. The subcoat may serve as a bonding agent or provide an intervening substance of predetermined refractive index to improve transmission or reflection of light rays relative to said body.

Fig. 23 shows, in cross-section, a light diffusing coating I96 applied to a surface portion of a lightmodifying body I98 of the invention, said coating being applied, for example, similarly to a method, presently to be described, of applying a light-polarizing fiuid to a fabric.

Fig. 24 shows, in cross-section, a composite light-modifying body or filament 200 comprising a spirally oriented coating or twist of filament components 202 formed around a preferably isotropic core 204, said coating or twist being birefringent and potentially light-polarizing and providing a predetermined crossed orientation of transversely opposite portions thereof. A protective coating 206 is formed upon a portion of twist or coating 202, it being assumed that said protective coating has been thus formed after filament 200 has been incorporated in a fabric. Coating 206 may be either temporary or permanent and, if the latter, it is transparent. If temporary, it is' adapted to be dissolved by a suitable organic or inorganic substance. Coating 206 is impermeable to a light-polarizing treatment such as a dye or stain. Upon application of a light-polarizing treatment to the fabric, exposed portions of coating or twist 202 are rendered light-polarizing while portions thereof covered by protective coating 206 are unaffected by said treatment. protective coating 206 may be dissolved if adapted thereto, as above described. A construction providing a light-polarizing portion and birefringent portion radially superposed therewith is thus formed, the optic axis of the birefringent portion being predeterminedly angularly disposed relative to the light-polarizing direction.

Alternatively, coating 206 may be a permanent reflecting or semi-reflecting coating so that at least part of the light entering the polarizing and birefringent portions is reflected substantially reversely along its path. In a construction where light passes through polarizing and birefringent layers to a reflecting surface and is thus reflected, the birefringent layer serves functionally twice, and the polarizing layer serves both as a polarizer and analyzer. Core 204 may also have predetermined anisotropic properties for coacting with said birefringent portions of coating or twist 202. In another modification, core 204 may be omitted After the light-polarizing treatment,

24 entirely and layer 202 may then consist of a twist of one or more components, or a spin of a plurality of components. Where layer 202 is in the form of a coating, several methods of providing an oblique or spiral orientation thereof will presently be described.

Fig. 25 represents a side view of a composite light-modifying body or filament 20I of a type described with respect to Fig. 24 and comprises 2. preferably substantially isotropic core 205 and a twist of birefringent components 203 formed. around the core, said twist being adapted to become light-polarizing when suitably treated. A transparent bonding substance, impervious to a light-polarizing treatment such as a stain or dye, may suitably exist between the core and twist, or the twist may be shrunk tightly upon the core. Directions of orientation of portions of the twist at opposite sides of the core are generally indicated by double-headed arrows 208 and 2 I 0. Core 205 may have predetermined anisotropic properties as stated with respect to Fig. 24. Filament MI is adapted to be employed in a fabric as, for example the warp, with a similar filament forming the filling. A plurality of filaments 20I may thus be incorporated in a fabric prior to a polarizing treatment thereof. After the fabric is formed, it may be treated with a coating substance for providing a protective coating over inner facing surfaces of warp and filling in the manner described relative to Fig. 24. Or, inner facing surfaces may be temporarily or permanently bonded together so as to be shielded from a light-polarizing treatment. The polarizing treatment, accordingly, affects exposed surfaces of the filaments only and birefringent portions are provided, interposed therebetween. The relation between optic axes of the birefringent portions and polarizing directions of polarizing portions is adapted to produce interference colors. The relation between birefringent and lightpolarizing axes may be altered by varying the twist angles of warp and filling filaments and by use of S and Z twists. Use of filaments having an oblique orientation such as that described relative to Fig. 9 may also be employed for further varying the relation of axes, or a combination of said variables may be employed.

Further referring to the above, a twisted monofilament or multifilament or a plurality of twisted filaments, as shown in Fig. 8, could similarly be incorporated in a fabric and subjected to a lightpolarizing treatment thereafter, provided the filament or filaments are birefringent and adapted to become light-polarizing when treated therefor. Light polarizing treatments of a fabric, which obviate the necessity of coating or bonding inner surfaces of filaments such as those set forth relative to Figs. 8 and 25, will presently be described. Self-sufficient bodies or filaments of the type hereinbefore described for producing interference colors may also be treated for providing their light-polarizing properties after incorporation in a fabric, provided transparent filaments crossed therewith in the fabric are substantially nonreceptive to the polarizing treatment.

Fig. 26 shows a composite light-modifying body or filament 2I2, partly in cross-section and with parts broken away. The filament is of a type previously described and may thus comprise a birefringent core 2M and a twist of light-po larizing components 2I6, having a direction of polarization 2I8, formed thereabout. Fig. 26 illustrates the transmittal of light relative to a filament of the invention wherein, for example, may exist an assembly of components having similar refractive indices or a core with a slight- Ly higher refractive index than the twist. Where desired, adjacent surfaces may be bonded, fused or coagulated together, as at 220, to insure optical contact of said surfaces, a bonding substance preferably having a similar refractive index to that of twist and/or core components, for maximum transmittal of light. For providing reflection of light at various surfaces, materials of different refractive index may be employed as, for example, a core having a lower refractive index than the twist. Bonding substances of appropriate refractive index may also be employed for the purpose as well as semi-reflecting coatings or the like.

Fig. 27 illustrates a swatch of a light-modifying fabric of the invention wherein self-sufficient filaments 222 for producing interference colors are employed with preferably transparent filaments 224 of any desired type. Filaments 222 may be of any of the forms described hereinbefore which are capable, of themselves, of producing interference colors and other effects and are shown having crossed polarizing axes 226, although such a relation of axes is merely illustrative. Filaments 224 may have various optical properties for coacting with filaments 222 or for otherwise contributing to the overall appearance of the fabric as, for example, they may be tinted. strongly reflecting, fluorescent or have some other functional characteristic. Moreover, they may provide some other desired characteristic of the fabric such as a texture effect, fire resistance, stability, strength or the like.

Fig. 28 represents a swatch of a light-modifying fabric of the invention wherein filaments 228 and 230 are of a type previously described which coact, as warp and filling, to produce interference colors and other effects. Accordingly, said filaments may comprise a light-polarizing core and a birefringent layer formed thereabout. Doubleheaded arrows 232 and 234 generally indicate the polarizing directions of warp and filling, respectively.

Fig. 29 illustrates a swatch of a light-modifying fabric wherein filaments 236 may appropriately be of the type shown in Fig. 28. Filaments 236 may, for example, be employed as warp in which event the filling 238 may suitably be composed of substantially transparent filaments such as filaments 224 of Fig. 27, previously described. A fabric of this type may be employed with an external source of polarized light for producing interference colors. If filling 238 is birefringent, alternate crossings of the filaments will provide portions having different retardation properties which will produce different interference colors from other portions. Two fabrics of the type shown in Fig. 29 could be bonded together, with either a parallel or angular relation of the polarizing directions thereof, to provide a composite fabric for producing interference colors. Filaments 236 may have polarizing directions 240 or I another direction, as hereinbefore described.

Fig. 30 shows a swatch of a light-modifying fabric with warp and filling comprising coacting filaments 242 and 244 having light-polarizing cores and birefringent surrounding layers for producing interference colors. The warp and/or filling also comprise preferably transparent elastic filaments 246. When the fabric is stretched as, for example, on the bias, the axial relation between filaments 242 and 244 is altered, providing different interference color effects and different transmission of light according to differences in the angular relation of said axes. Alternatively, filaments 242 and 244 may be lightpolarizing, without birefringent coatings, for altering light transmission only, in which instance a tint or dye may be incorporated therewith for providing a constant color to light of variable intensity. It will be apparent that elastic filaments 246 may also thus be tinted or dyed. Elastic light-modifying filaments of the type described relative to Fig. 5 may also be employed in the fabric of Fig. 30 in place of either filaments 244 or 246, or both.

Figs. 31 and 32 illustrate light-modifying bodies or filaments of types described herein, which are associated with a film or other component or components to form composite structures. In Fig. 31, a plurality of said light-modifying bodies 252, capable of producing interference colors, are formed into a fabric or the like with a plurality of preferably transparent filaments 254 and said fabric is bonded by a transparent adhesive substance 256 to a film component 258. Film component 258 may be of a relatively nondeformable type or may have pronounced qualities of drape. Said film component may be transparent, translucent, diffusing, dyed or have some other quality according to the intended use of the structure. Alternatively, film 258 may be in the form of a fabric or some other material having generally similar optical qualities to those described relative to the film. In another modification filaments 252 and 254 may be of the type, above described, which coact to provide interference colors In a further modification, at least one of filaments 252 and 254 may comprise a lightpolarizing core and a. layer of birefringent or optically active material and film 258 may comprise light-polarizing properties, the polarizing axes of the filaments and film being suitably oriented. In still another modification, film 258 could comprise both light-polarizing and birefringent or optically active properties while at least one of filaments 252 and 254 could be light polarizing. Other modifications will readily be apparent in view of various constructions described herein. The fabric may be embedded in a transparent film or laminated between film components. In the last named form, the lightmodifying bodies could be self-sufficient for producing interference colors or could be merely birefringent or optically active bodies, the film components being at least light-polarizing.

Fig. 32 shows a plurality of light-modifying bodies 250, having self-sufficient or coacting properties of the type described herein,.bonded by a transparent substance 262 to a film component 264. Said bodies may be oriented, as generally indicated, or may be disposed at random on the surface of the film. Substantially all of the modifications described relative to Fig. 31, omitting those requiring filaments 254, are applicable to the construction of Fig. 32. It will be apparent that filaments of the present invention may be severed to form short staple fibers or abbreviated bodies for use in conjunction with a fabric, film or other material, in the general manner above described. Accordingly, they may be bonded to or embedded in various materials for many purposes where the production of interference colors is an objective. It is also to be understood that other fabric constructions comprising filament components of the invention may be incorporated with film materials. The invention also contemplates the provision of an artificial fabric formed of a film-like material comprising light-polarizing and birefringent or optically active components having principal and polarizing axes suitably disposed relative to one another for producing interference colors in the manner described herein. Said material could be formed of thin laminae or could readily be formed by the method described relative to Figs. 9 and 35. The artificial fabric could comprise an embossed, etched, printed, flocked or otherwise treated surface to generally resemble a fabric, or it might have a laminated or embedded netting or the like, or other internal structure for providing a substantially similar resultant. The interference colors, which would generally be visible, could be extinguished wherein such constructions provided opaque lines of demarcation, or could be differently visible, due to diffraction or other effects, where transparent or translucent lines of demarcation were provided. The artificial fabric could have pronounced qualities of drape or be relatively nondeformable, according to desired characteristics thereof.

Figs. 33 and 34 illustrate the adaptability of light-modifying fabrics of the type described herein to be draped in various contours substantially without affecting the orientation of their light-modifying components. Fig. 33 represents such a fabric 266 laminated to a spherical surface 268. Fig. 34 illustrates a draped fabric 210 of said type embedded in a molded transparent plastic body 212 or the like. The double-headed arrows indicate the presence of vibration directions of light-polarizing materials rather than any specified direction thereof. Where the fabrics are draped, so that curved areas thereof are formed, various merging interference effects will be visible to an observer while viewing said areas from any position, said effects relating to gradations of color and luster and being unobtainable in any conventional fabric. As employed in Fig. 34, a fabric of the invention may be deformed according to the requirements of a molded product for producin interference colors therein. The fabric may also serve to strengthen the product in a known manner.

Fig. 35 is a diagrammatic representation of apparatus for forming a light-modifying body of the type shown in Fig. 9. Means such as a spool 214 releasably holds a supply of a filament, strip or ribbon of orientable transparent plastic material 216. The material 216 is of a type adapted to be rendered birefringent after undergoing stretch, or to be converted into a polarizer when stretched. Or. material 216 could be of a preliminarily treated type which is adapted to be converted into a polarizer by a stretching process. The material is drawn between preferably freely rotatable pressure rollers 218 and is then twisted or folded in a given direction and to a predetermined degree as by twisting or folding means 280. It then passes, in twisted or folded form between powered pressure rollers 282 and is subjected to softening means, as required. such as heat-applying means 284. Thereafter, it passes between powered pressure rollers 286, which rotate at a predeterminedly greater speed than rollers 282, so that the twisted or folded material is predeterminedly stretched in the area between rollers 282 and 286, internal orientation being longitudinal of the twisted material as a whole, as shown in Fig. 9. After leaving rollers 286, the material is untwisted or unfolded by untwisting or unfolding means 281 and an oblique orientation, as indicated by double-headed arrow 288, is provided therein. The material is then drawn between pressure rollers 290, which may appropriately be powered to rotate at a more rapid speed than rollers 286, to take up the slack of material 216 produced by untwisting the same. The material is then taken up by means such as powered spool 292. Instead of being drawn from spool 214, the material may be supplied from an extruder 294, shown diagrammatically in Fig. 36, said extruder being suitably positioned to the left of dotted line 0-0 (Fig. 35). Alternatively to passing from rollers 290 to take-up spool 292, the material may be directed to a coating device 296 (Fig. 3'1), said device being suitably positioned to the right of dotted line d--d (Fig. 35). Element 296 may appropriately comprise guide rollers 298 and 299 and a container 300, holding a suitable coating substance 302 which, after its application to material 216, is adapted to be rendered birefringent by stretching means 304, 306, and 308, which are similar in function to means 282, 284, and 286 but which may apply a different stretch to the coated material as, for example, a lesser stretch. The material is then taken up by means 310. It will be understood that if material 216, as supplied to coating device 296, is of a form whereby the first stretching procedure performed by elements 282, 284 and 286, or said procedure plus a lightpolarizing treatment, render the material polarizing, that the coating and stretching means of Fig. 37 complete a continuous process of forming a body, such as a strip or filament, comprising a light-polarizing component having an oblique orientation, with a birefringent layer having, for example, longitudinal orientation, coated upon the light-polarizing component. Said light-polarizing treatment could be provided by means 362 of Fig. 39, presently to be described.

Further relative to Fig. 35, if a body such as a strip or filament comprising an obliquely oriented central portion or core with a polarizing layer having a different orientation formed thereupon is desired, a modification of Fig. 35 for forming the same is as follows. Material 216 is rendered birefringent with an oblique orientation by twisting and stretching means of Fig. 35, already described. Means of Fig. 3'1, inserted at d-d of Fig. 35, may be assumed to provide a coating of potentially light-polarizing substance 302 upon material 216, which is hardened sufficiently for stretching upon leaving tank 300. The coated body is stretched by means 304, 306, and 308 to a degree which does not disrupt the oblique orientation of material 216 but which provides a generally longitudinal orientation of coating 302. Polarizing treatment means, such as means 362 of Fig. 39, may then be employed prior to taking up the body upon means 3 l0. Alternatively, material 216 may be supplied to coating device 296 either after said oblique orientation has been provided therein or without having been subjected to the twisting and untwisting means, namely, with means 280 and 281 removed from the apparatus, in which latter instance material 216 would have a longitudinal orientation. Coating 302 could consist of either of the aforesaid types of orientable material which are adapted to be oriented when hardened and stretched. By spreading the position of the elements, twistin and untwisting means 280 and 281 could, respectively, be repositioned before and after stretching means 304, 306 and 308. Accordingly, material 216 would be provided with a given orientation, as above described, and the coating there-

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