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US2892383A - Light-polarizing process and product - Google Patents

Light-polarizing process and product Download PDF

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Publication number
US2892383A
US2892383A US595212A US59521256A US2892383A US 2892383 A US2892383 A US 2892383A US 595212 A US595212 A US 595212A US 59521256 A US59521256 A US 59521256A US 2892383 A US2892383 A US 2892383A
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solution
dye
light
sheet
film
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Vivian K Walworth
William H Ryan
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Polaroid Corp
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Polaroid Corp
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
    • G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C9/00—Stereo-photographic or similar processes
    • G03C9/04—Vectographic-image

Definitions

  • This invention relates to processes for providing improved dichroic dye light-polarizing means characterized by having one or more dichroic dyes which are predeterminedly distributed in each light-polarizing layer of said means and held fast therein by a basic nitrogen-containing dye mordant present in each said layer, and especially relates to processes providing light-polarizing means of this nature in the form of image-bearing film which carries dichroic dye images, and further relates to the products produced by said processes.
  • Objects of the invention are to provide improved processing treatment whereby to raise the dichroism of dichroic dye light-polarizing means of the character having one or more light-polarizing layers of a transparent, molecularly oriented, linear, high molecular weight, hydroxyl-containing, vinyl polymer which each contains a dye mordant comprising a basic nitrogen-containing compound and which have each been dyed with a dichroic dye, by subjecting each said layer to the action of a solution of at least one electrolyte of the character containing at least one ion from the class consisting of anions and cations selected from the lyotropic series and of greater activity in said series than barium or chloride; and further to provide processes of the character described for treatment of substantially uniformly dyed di chroic dye polarizers or for light-polarizing image-bearing films which may contain one or more monochromatic or multicolor dichroic dye images of a two-dimensional or stereoscopic nature.
  • Further objects of the invention are to provide improved processes for producing dichroic dye light-polarizing means of the character described as having one or more dyeable layers of oriented plastic material which each has a dye mordant of the character set forth dis persed therein and wherein each dyeable layer is predeterminedly dyed with at least one dichroic dye, following which each dyed layer is treated with a solution of at least one electrolyte of the character described; and to provide processes of this nature for producing a substantially uniformly dyed light-polarizing layer or one or more dichroic dye light-polarizing images of the char acter described in an image-bearing layer; as Well as to provide processes for producing dichroic dye lightpolarizing means wherein the polymer which provides each light-polarizing layer thereof is subjected to the action of a similar solution of at least one electrolyte at some stage prior to the predetermined dyeing of said layer, and wherein each said layer after being dyed is subjected to aftertreatment with said solution of said elecolyte.
  • a still further object is to provide light-polarizing products produced by processes of the character de scribed.
  • the invention accordingly comprises the several steps and the relation and order of one or more of such steps with respect to each of the others, and the products possessing the features, properties and the relation of elements which are exemplified in the following detailed disclosure, and the scope of the application of which will be indicated in the claims.
  • Figure 1 is a diagrammatic illustration showing the manner of forming stereoscopic pairs of superposed lightpolarizing dye images in molecularly oriented film stock by the application to each side of the film stock of a printing matrix which contains, as a relief image, one of a stereoscopic pair of images to be printed and which is wet with a dichroic dye solution;
  • Fig. 2 is a diagrammatic perspective view of a stereoscopic color print produced on the film stock by the procedure illustrated in Fig. l.
  • One practice for producing a light polarizer is to introduce a dichroic dye into a transparent, molecularly oriented, linear, high molecular weight, hydroxyl-containing, vinyl polymer of which a preferred example is polyvinyl alcohol.
  • a dichroic dye is adsorbed in a molecularly oriented plastic sheet of this nature, it
  • the present invention is concerned with techniques for providing improved light-polarizing products of the character heretofore set forth. To assist in the full understanding of the nature of these techniques and the improvements provided by their use, it seems desirable at the outset to point out the general nature of the products involved and the general manner by which dye polarizers are produced.
  • a suitable medium or stock in which superposed, light-polarizing stereoscopa ic leftand right-eye images may be formed is providedby the film stock or printing blank 30 illustrated in Fig. 1 as comprising a laminar structure having two thin and transparent surface layers 31 and 32 mounted upon the opposite sides of a transparent support 33.
  • the surface layers 31 and 32 are thin sheets of a transparent, molecularly oriented, high molecular weight, hydroxyl-containing, vinyl polymer of which a preferred example is polyvinyl alcohol, while the support 33 is any suitable transparent and substantially water-impermeable plastic such as cellulose acetate butyrate or cellulose triacetate.
  • Sheets 31 and 32 are prepared by conventional prac-- tices such, for example, as making a suitable casting composition of polyvinyl alcohol and into a sheet. Alternatively, the composition may be applied as a coating onto an already formed sheet of polyvinyl alcohol. Regardless are formed, they may be laminated by conventional means to the transparent support 33.
  • the layer 31 has its molecules so oriented that the transmission or polarizing axis of the layer will' be at 45 to the edge of the film stock 30, while the layer 32 has its molecules so oriented that the transmis-' sion or polarizing axis of the layer will also be at 45 to the edge of the film stock but will make an angle of with the transmission axis of the layer 31.
  • This preferred orientation for film stock is indicated by the arrows 41 and 42 in Fig. 2 which schematically illustrates film stock 30 after image formation therein.
  • the film stock 30 provides a transparent structure useful as motion picture film or cut film. Additionally, the film stock 30 may be mounted upon an opaque, nonpolarizing, refiecting base and used for the formation of light-polarizing reflection prints. Stereoscopic image pairs formed in the film stock 30 will be located in superposed relation to each other.
  • One general practice for carrying out image formation in film stock 30 is effected with conventionally prepared gelatin washoff relief printing matrices which are each provided with one or more appropriate relief records to be reproduced in a layer of the film stock, such for example as red, green and blue separation records of a three-color image to be reproduced.
  • Two sets of matrices are employed in stereoscopic reproduction of which a first set bears left-eye image records of each stereoscopic image pair to be printed in film 30, while the other set bears corresponding right-eye images.
  • the individual matrices of each set are dyed with a dichroic dye or dyes and are successively pressed into registered contact with the layer of the film stock 30 in which they are to reproduce an image by dye transfer.
  • the red, green and blue printing matrices are respectively used to print cyan, magenta and yellow component images by means of dye solutions of these colors which are imbibed therein and may be printed in the order just named.
  • FIG. 1 A convenient means for simultaneously printing on opposite sides of the film stock 30 is schematically illustrated in Fig. 1 wherein the film stock 30 with a righteye printing matrix and a left-eye printing matrix superposed on opposite sides thereof is shown as being passed between two rotating pressure-applying rolls 35 which cause the matrices to be pressed into intimate contact with the outer molecularly oriented layers 31 and 32 of the film stock.
  • Fig. 2 -A transparency or product resulting from the utilization of the procedure illustrated in connection with Fig. 1 is diagrammatically shown in Fig. 2 wherein film stock 30 is illustrated as containing a right-eye stereoscopic image 310 in the molecularly oriented layer 31 and a left-eye stereoscopic image 320 in the molecularly oriented layer 32. Image 310 is shown in full lines while image 320 is shown in dotted lines.
  • the product shown in Fig. 2 has been considered as derived from a pair of stereoscopic records of the letter H and, in accordance with the process heretofore described, may be considered as providing a fullcolor stereoscopic transparency.
  • Viewing is carried out by observing these light-polarizing images 310 and 320 through polarizing filters located in front of each eye of the observer with the transmission axes thereof positioned at 90 to each other. Additionally, the light-polarizing filters are so positioned with respect to the light-polarizing images in the film 30 that each has its respective polarizing axis crossed or at 90 to the polarizing axis of the image to be observed therethrough. In this way, each eye sees substantially only the image intended for it.
  • the printing of light-polarizing images in the film stock of this invention is in no way restricted to the employment of gelatin washoff relief matrices. Any other procedure may be employed.
  • the invention embraces the use of photomechanical printing plates or matrices such as halftone, line drawing and lithograph plates or matrices as means for printing images.
  • Photomechanical printing matrices may be used for printing dichroic dye images directly in undyed and oriented sheet stock which has been subjected to the pretreatment practices of this invention.
  • a photomechanical printing matrix may be used to print a resist'area on 'oriented'sheet stock which has been pretreated and substantially uniformly dyedinaccordance with the practices set forth herein, following which the dye, in portions of the stock uncovered by the resist, is bleached.
  • the polarizing and bleached nonpolarizing areas may be used for positive and negative image formation or vice-versa.
  • Photomechanical printing is carried out by applying the matrix, after it has been wet or inked with a dichroic dye or a resist, into pressure contact with the sheet stock.
  • the inventive concepts of this invention embrace sheet polarizing means broadly.
  • the layers 31 and 32 may be rendered light polarizing all over by substantially uniformly applying a dichroic dye to either or to both of said layers.
  • a sheet structure for conversion into a uniform density dye polarizer will comprise a transparent support such as the support 33 and an oriented layer such as the layer 31. Structures of this general nature and suitable for providing overall dichroic dye polarizers are disclosed in Patent No. 2,237,567.
  • the film stock 30 may be employed to provide two-dimensional light-polarizing dye images by limiting image reproduction to one of the layers 31 or 32, although in such event it is generally preferable to employ a structure comprising the support 33 and only one image-bearing layer.
  • the molecular orientation of a plastic sheet is customarily carried out by stretching the sheet in the presence of heat and by'the application to the sheet of opposed tensional forces. As will be well understood, the result of such stretching is to cause orientation of the molecules of the sheet in a direction which is substantially parallel to the direction of application of the opposed stretching forces.
  • the degree of stretching imparted to a plastic sheet is conventionally measured by what is called the axial ratio which is a quantity determined by the ratio of the major axis to the minor axis of the ellipse appearing on the plastic sheet after the sheet is stretched and is derived as a result of the stretching of said sheet from a circle printed on the sheet before stretching.
  • the higher the axial ratio the higher the efficiency of the sheet as a light polarizer.
  • Axial ratios of 3 and greater are of a nature suitable for providing molecularly oriented sheet of high orientation.
  • Current production practices are consistently carried out to provide axial ratios of around 6 for molecularly oriented polyvinyl alcohol sheet.
  • the present invention is concerned with molecularly oriented plastic sheet stock which has an axial ratio of, or higher than, the value just noted.
  • One effect of stretching a plastic sheet is to cause the sheet to develop a resistance to dissolution in aqueous solution at given temperature.
  • this decreases in solubility of the plastic matcrial in aqueous solution is a function of the degree of its molecular orientation.
  • Such decrease in the solubility of the plastic material affects the ability of an aqueous solution to permeate a sheet of the same and, at least to some extent, affects the introduction of the desired quantity of a dichroic dye solution into the sheet, whereby the resulting product may lack the desired dye density.
  • the present invention proposes to treat the material of the sheet or layer to be dyed with a solution comprising a special reagent or combination of reagents adapted to render the material more readily receptive to dye which is introduced therein in aqueous solution.
  • This treatment is designed to promote dye transfer to a dyeable layer from a printing matrix or the introduction by other means of dye from an aqueous solution into a layer of dyeable material byincreasing the quantity'of dye removed from" the matrix or solu tion'and by'speeding"'up'the-rate'of'dye transfer or ini t'roduction.
  • a result of this treatment is to provide products having a dye density greatly increased over untreated products of this character.
  • pretreating reagent While such removal of a pretreating reagent is generally desirable, the need thereof is dependent upon a number of factors such as the reagent concentration of the pretreating solution, the presence in the pretreating solution of a reagent which will form surface scum or surface irregularities in or on the finished plastic sheet, the presence in the finished plastic sheet of a reagent which is adversely afiected by changes in the pH of the sheet brought about in the dyeing thereof, and the presence in dry sheet of a reagent capable of reacting with a solution which is used to wet the sheet prior to dyeing it as well as other and similar factors,
  • the invention includes the pretreatment of plastic material comprising the sheet when said material is in the form of flake whereby to render the material more receptive to an aqueous dye solution, followed by the conventional formation of the flake into a sheet.
  • the invention also contemplates the dyeing of the flake itself or the sheet formed thereof.
  • the specific practices of the illustrative examples of the invention suited for the pretreatment of plastic flake but, as will become apparent to the art, are subject to variation and simplification.
  • the invention contemplates the pretreatment of sheet stock, for example preformed sheets of polyvinyl alcohol, which are in oriented or unoriented condition.
  • sheet stock for example preformed sheets of polyvinyl alcohol, which are in oriented or unoriented condition.
  • the dyeing of a preformed sheet may take place prior or subsequent to the orientation of the sheet.
  • dichroic dye images are to be reproduced in sheet stock, it is generally preferable to orient the molecules of the image-bearing layers of the stock before the dyeing step is carried out.
  • a basic nitrogen-containing mordant is described in the application of William H. Ryan and Vivian K. Walworth, Serial No. 444,074, filed July 19, 1954, which discloses the use of basic nitrogencontaining mordants incorporated in molecularly oriented hydroxyl-containing vinyl polymers.
  • Other suitable mordants include the amino-containing polyethylenic compounds set forth in the application of Elkan R. Blout, William H. Ryan, Vivian K. Walworth and Howard C. Haas, Serial No.
  • the mordant may be introduced into the sheet material by including it in the casting composition from which the sheet is cast or otherwise formed. The sheet containing the mordant is then subjected to stretching to orient the molecules thereof. Alternatively, the mordant may be introduced into a preformed sheet, which has its molecules in oriented or unoriented condi tion, by the' imbibition into the sheet of an appropriate solution of the mordant.
  • a highly desirable result provided by pretreatment methods of the type described herein with respect to dyeing oriented plastic sheet, either alone or by combining these methods with a suitable mordant, is the limitation or restriction of lateral diffusion of a dye or dyes introduced to the sheet from a printing matrix so that the printed dye image formed in the oriented sheet or layer faithfully reproduces the fine detail of the matric image.
  • the requirements relating to resolution of dye images are particularly exacting where projection prints such as slides or motion picture prints are contemplated. In' producing prints through methods of the present invention as, for example, in the production of stereoscopic image pairs of the invention, image resolution in excess of 60 lines per mm. is readily obtained.
  • a dichroic dye there is meant a dye whose molecules possess the property of showing dichroism. In the practice of the invention, this property is displayed when said dye is incorporated in molecularly oriented plastic materials in that the resultant stained areas show dichroism.
  • dichroism is used herein to mean the property of differential absorption of the components of an incident beam of light depending upon the vibration directions of said components.
  • the optical density of each area of a light-polarizing image is a function of the vibration direction of light. incident thereon.
  • Light-polarizing images of the nature described are rendered not only in terms of density difference but in degree of light polarization and have low polarizing etficiency for light areas but high polarizing efliciency for dark areas.
  • a light-polarizing image is seen through a polarizer the axis of which is parallel to the polarizing axis of the image, it has extremely low contrast or may be totally invisible.
  • a polarizer whose axis is at right angles to that of the light-polarizing image, the image is seen at its normal contrast.
  • the pretreating and aftertreating reagents with which this invention is concerned are electrolytes, including aqueous solutions of one or more acids, or bases or salts.
  • a solution of one or more electrolytes there is meant an aqueous solution of one or more substances each of which dissociates in said solution to form ions having positive or negative charges.
  • the present invention cornprehendsthe use of inorganic as well as organic substances of the nature just set forth.
  • an electrolytic solution there is meant a solution of one or more electrolytes.
  • anions and/or cations present in a solution of an electrolyte to affect the characteristics or properties of hydrophilic colloids when in contact with a surface of the colloid, or when they have penetrated through said surface, is well recognized in the art.
  • one or more of the ions present in such a solution have beenemployed to affect the adsorption characteristics of surfaces in colloidal systems, to break up colloidal suspensions and to swell or dissolve hydrophilic polymeric material.
  • the literature abounds with. disclosures of the action of ions in the treatment of a variety of different materials and shows that certain ions are more effective in their action than are others.
  • the lyotropic series may mediately below:
  • first or upper line of the series represents anions arranged in ascending order of activity or effectiveness from left to right
  • second and lower line of the series represents cations arranged in ascending order of activity or effectiveness, as a colloid swelling agent, from left to right.
  • anions C10 and OH represent the maximum differences in effectiveness between the anions of the series
  • the cations K and H represent the maximum diiferences in effectiveness between the cations of the series.
  • emphasis is directed to the activity of ions in the lyotropic series in relation to the ability of the ions to swell colloids or to render colloids more penetrable to a liquid or a solution applied thereto after pretreatment with a solution containing at least one ion of the lytropic series.
  • lyotropic series appears in scientific literature, it is generally set forth in association with the explanation of some specific phenomena so that frequently the investigator or writer will include only ions which best illustrate his explanation. As a result, the series is not always set forth completely.
  • the lyotropic series is a compilation made from the following recent publications: Emil Ott, H. M. Spurlin and M. W. Graffiin, Cellulose and Cellulose Derivatives, part I, second edition, volume V of High Polymers, Interscience Publishers, Inc., New York, 1954-, and Ernest A. Hauser, Colloidal Phenomena, chapter 10, the Technology Press, M.I.T., Cambridge, Massachusetts, 1954.
  • the present invention is concerned with treatment by a solution of at least one electrolyte containing at least one ion, either an anion which has greater eifectiveness or activity than chloride or a cation which has a greater effectiveness or activity than barium in the lyotropic series. It may be noted that in carrying out the practices of this invention, it is unnecessary that both cations and anions of the just-noted order of eifectiveness be employed. The invention is successfully carried out where only one such ion results from the dissociation of the substance which provides the solution. It is also comprehended by the invention to utilize two or more ionizable substances at least one of which possesses one of the desired ions, while the other may or may not possess an ion that falls within the useful range of the lyotropic series.
  • activity is employed herein to indicate the ability of an ion (cation or anion) toswell hydrophilic colloids or to increase their penetrability to liquids subsequently brought into contact therewith.
  • ion cation or anion
  • increasing activity, greater activity and the like there is meant the ability of any ion in the lyotropic series to show increased effectiveness over any ion located below it in said series to swell a colloid as by causing said swelling to take place more rapidly and/ or to a greater degree.
  • Such meaning of these terms in regard to activity is also intended to include the ability of any ion in the lyotropic series to show an increased efiectiveness over any ion located at a lower position in the series and the ability of the, ion of higher position to place a hydrophilic colloid in a condition where liquids, applied thereto after pretreatment with a solution containing said ion of higher position, will more rapidly penetrate the colloid or penetrate it to a greater degree than if the colloid had been treated with a solution containing an ion of lower position in, saidseries.
  • Some examples of other substances which provide suitable solutions for pretreatment and aftertreatment purposes are as follows: sodium thiocyanate, lithium nitrate, potassium mercuric acid-chloride, sulfamic acid, triethanolamine, monoethanolamine, ammonium hydroxide, zinc salicylate, boric acid, ammonium thiocyanate, lithium iodide, calcium chloride, potassium iodide, trisodium phosphate, strontium iodide and sodium iodide.
  • pretreating practices contemplated by this invention involve the processing steps of absorbing a pretreating solution into sheet stock or the plastic material thereof, followed by the partial or complete drying thereof, and may include the removal of at least a part of the pretreating reagent or reagents from the plastic material as, for example, by means of a water rinse carried out before drying.
  • These practices are subject to variations within the specified limits, depending upon the concentration and character of the reagent or reagents of the pretreating solutions, the physical form of the plastic material operated upon, the time sequence of subsequent processing to convert the pretreated plastic material into one of the types of dichroic dye polarizing means heretofore mentioned, and other similar considerations.
  • pretreatment of preformed sheet stock which is itself in oriented or unoriented condition is initiated by immersing the stock in the aqueous solution of the reagent, or by flowing said solution onto the stock or otherwise bringing the solution into contact therewith.
  • Pretreatment of the material from which the sheet stock is to be subsequently formed is carried out by wetting said material with the pretreating solution as by immersion therein preparatory to forming the flake into oriented sheet stock.
  • Treatment of the plastic material with a solution of one or more appropriate electrolytes may be carried out over a wide temperature range, i.e., from 32 F. to 120 F. and higher with aqueous solutions having a reagent concentration of from 0.5 to 30% and for time periods of from 30 seconds to five minutes.
  • treatment time is decreased with increase in temperature and also by employment of a high concentration of the electrolyte or electrolytes employed, although the treatment time will be influenced by other factors such as the order of activity of the ions provided by the pretreating solution and the axial ratio of the sheet stock undergoing treatment in instances where oriented sheet is treated.
  • pretreated sheet stock which is in a dry condition is to be preferentially dyed by means of an aqueous dye solution transferred thereto from a printing matrix brought into contact therewith. It is desirable to wet the sheet stock before pressing the printing matrix thereon and preferably to wet the stock with a solution of one or more reagents which improvedye transfer. If the reagent or reagents. of the pretreating solution are of a character which will not 'form' stantially to completion.
  • pretreating reagent or reagents A similar situation exists when the same reagent is used in a pretreating solution and in a prewetting solution and the reagent is one which produces no undesired effects. In addition, in some instances where the pretreating reagent is used in low concentration, deleterious elfects, which may be caused thereby, will be so minimized that it may also be possible to omit rinsing the pretreated plastic material prior to the drying thereof.
  • Neutralization following pretreatment with sodium hydroxide is effected by contact of the sheet or the material thereof with an 0.5 to 1% solution of acetic acid for about one minute at room temperature. Following neu-' tralization, the sheet stock or the material thereof is again rinsed in water. In instances where neutralization treat ment is omitted, only one water rinse will be carried out.
  • pretreating solution from sheet stock or the plastic material thereof is by drying.
  • the sheet may be dried by a warm air blast and if it has been subjected to rinsing prior to drying, rinse water may 'be blown off the sheet With an air knife or otherwise removed as by a squeegee. While removal of excess liquid from the surface of the sheet as by reagent in solution in said liquid, it will be realized that such treatment primarily serves to facilitate drying and can, of course, be omitted.
  • oriented sheet or film stock such as that shown in Fig. 1, may take place either prior to pretreatment or after pretreatment.
  • preformed sheet material or the plastic flake from which the sheet is formed is being pretreated, it is generally unobjectionable, as pointed out, to subject the pretreated sheet or flake to rinsing followed by a drying operation which may be carried out substantially to completion.
  • oriented sheet stock which has been pretreated may be stored for extended periods prior to the dyeing thereof. This characteristic of the sheet stock is credited to the ability of the stock to retain the beneficial properties imparted thereto by pretreatment.
  • dichroic dye images of about the same desired degree of quality as regards maximum dye density, resolution and dichroisrn have been printed on oriented film stock which is of the character illustrated in Fig. 1 and which has either been-held in storage for several months after its pretreatment, or which is used immediately following pretreatment.
  • the film stock referred to in each of these examples is of the character of the film stock 30 of Fig.1 which includes layers in oriented condition and which is employable as motion picture film or cut film for the production of stereoscopic dichroic dye images.
  • the individual steps in each specific example of pretreatment are numbered consecutively.
  • EXAMPLE II Wet oriented film stock four minutes with 2% calcium thiocyanate solution at about 120 F.
  • EXAMPLE III Wet oriented film stock four minutes with zinc chloride solution at about 120 F.
  • EXAMPLE IV Wet oriented film stock four minutes with lithium chloride solution at about 120 F.
  • Example I the neutralization step and the second rinse step of Example I are employed in instances where solution 3 in the just foregoing is used for pretreatment purposes. Furthermore, in regard to solution 3, sodium carbonate is employed therein because it may be advantageously employed to toughen an oriented polyvinyl alcohol film due to its ability to precipitate polyvinyl alcohol from aqueous solution.
  • the oriented sheet stock after pretreatment is ready for dyeing.
  • dichroic dye images are to be printed in oriented film stock, such as the film stock 30' of Fig. 1, it is generally desirable to wet the film stock, as the provision of film stock in a wet condition assures good overall contact between the surface being printed and the relief printing matrix pressed thereon.
  • a 5% solution of sodium acetate or an aqueous solution of sodium benzoate and sodium sulfate wherein the sodium benzoate has a concentration of 1% and the sodium sulfate of 4% and other alkali metal salts of weak organic acids.
  • Application of a prewetting solution is carried out by dipping the sheet therein for a period of from a few seconds to one or two minutes at temperatures ranging from room temperature up to F.,. after which excess solution is removed from the surface to be dyed preparatory to the dyeing step.
  • Other prewetting solutions are disclosed in the copending joint applications of William H. Ryan and Vivian K. Walworth, Serial Nos. 431,341 and 431,396, both filed on May 21, 1954.
  • dichroic dye images are formed in the pretreated oriented film stock by appropriate direct cotton dyes transferred thereto from printing matrices which are pressed into contact with the film stock and which have aqueous dye solutions imbibed therein.
  • pretreated and oriented sheet stock is to be uniformly dyed to provide a uniform density dichroic dye polarizer, there are no problems as to printing matrix contact so that prewetting treatment prior to dyeing is generally unnecessary and dye imbibition may be carried out without this preliminary step.
  • direct cotton dyes of an essentially elongated structure may be named as suitable for forming light-polarizing images in molecularly oriented plastic materials, and especially molecularly oriented polyvinyl alcohol.
  • Dyes of this nature are set forth in the previously mentioned patents.
  • suitable dyes mention may be made of Niagara Sky Blue 6B (Cl. 518), Azoform Brilliant Blue G (Cl. 516) and Erie Fast Green CGB ((3.1. 589) for cyan; Solantine Red 8BL (C.I. 278), Solantine Pink 4131. (C1. 353) for magenta; and Solantine Yellow 4GL (Prototype 53), Stilbene Yellow 3GA (Cl. 622) and Solantine Orange 46 (Prototype 578) for yellow. Further reference to other suitable dyes appears in the examples which subsequently follow.
  • This aftertreatment of mordanted film stock is carried out by contacting the dyed stock with a solution containing ions within the named range of the lyotropic series much in the same manner as the pretreatment of the undyed but oriented stock.
  • a specific example of aftertreatment follows:
  • Example I When sodium hydroxide solution is employed in aftertreatment, the neutralization step of Example I is generally unnecessary. Also, it is noted that it is unnecessary to subject unmordanted sheet stock to aftertreatment since the benefits derived thereby are substantially negligible.
  • aftertreatment reagents which may produce undesired etfects, such, for example, as by forming a scum on the surface of the printed film or by making the film stick.
  • rinsing following aftertreatment is not always necessary as, for example, in instances where the concentration of the aftertreatment solution is sufficiently low or the reagent or reagents used therein are of a nature which will cause no deleterious effects.
  • the aftertreatment solution possesses a reagent concentration which is considerably lower than the concentrations given for sodium hydroxide pretreatment solutions.
  • a low concentration of active reagents in aftertreatment solutions is desirable so as to make it possible to easily remove them after the solution has carried out its function.
  • any of the pretreatment solutions named in Examples I through V are suitable for use as aftertreatment solutions, although it is preferable to employ a lower concentration of the reactive ingredient or ingredients named.
  • aftertreatment solutions employ an active reagent concentration of from about 0.5% to and are employed at temperatures ranging from about 70 F. to 120 F. Time periods for aftertreatment are influenced by the concentration of the treating solution and by temperature.
  • each strip comprising film stock of the nature of the film stock 30 of Fig. 1 and having oriented layers of polyvinyl alcohol 31 and 32, with each image-bearing layer having an axial ratio of 6 or more.
  • EXAMPLE VIII This example sets forth the effect of pretreatment on the density ratio of unmordanted oriented film stock.
  • the Erieform Violet 2R in Example VIII is a dye made by the National Aniline Division of Allied Chemical & Dye Corporation.
  • EXAMPLE X This example sets forth the effect of pretreatment on the maximum dye density of both mordanted and oriented film stock and unmordanted and oriented film stock.
  • a mordant provides a means for readily obtaining a highly satisfactory reso lution for motion picture projection purposes.
  • monochromatic as well as multicolor stereoscopic dichroic dye images have been consistently produced by the practices of this invention which utilize a mordant to provide images having a resolution approaching 70 lines per mm. While it is difficult to obtain the desired minimum acceptable resolution'without the use of a mordant, it may be observed that monochromatic-andmulticolor dichroic dye images providing stereoscopic pairs'having a resolution closely approaching 60 lines per mm. have been consistently produced by the practices of this invention in oriented and unmordanted film stock. Stereoscopic dichroic dye images of a resolution lower than 60 lines per mm. are, of course, highly useful in the production of prints and transparencies which are to be viewed by hand and not projected.
  • a process for producing light-polarizing means of improved dichroism comprising the steps of forming into a film a transparent, linear, high molecular weight, hydroxyl-containing, vinyl polymer having distributed therein a basic nitrogen-containing dye mordant, orienting the molecules of said film, dyeing said polymerwith at least one solution of a dichroic direct cotton dye, and, after dyeing said film, absorbing thereinto a solution of at least one electrolyte,-the ions of which include at least one ion of the class consisting of anions and cations selected from the lyotropic series and of greater activity in said series than barium and chloride, whereby the density ratio of said light-polarizing means is raised appreciably over that of light-polarizing means formed by a similar process excepting the step of treating said film with said electrolyte solution.
  • a process for producing stereoscopic pairs of dichroic dye images of improved dichroism comprising the steps of forming two layers of a transparent, linear, high molecular weight, hydroxyl-containing, vinyi polymer having distributed substantially.uniformly therein a basic nitrogen-containing dye mordant,
  • each image of saidastereoscop c image pair is a multicolor image comprising cyan, magenta and yellow component images.
  • each'said layer comprises polyvinyl alcohol.
  • a process for producing light-polarizing means of improved dichroism having at least one molecularly oriented layer containing a dichroic dye so as to be rendered light-polarizing comprising the steps of forming into a dyeable film a transparent, linear, high molecular weight, hydroxyl-containing, vinyl polymer having distributed thereina basic nitrogen-containing dye mordant, orienting the molecules of said film in one direction, laminating said'film toa supportnig sheet material, dyeing said film'with at least one solution of a dichroic direct cotton dye to render said film light-polarizing wherever dyed, and absorbing into said dyed film a solution of at least one electrolyte, the ions of which include at-least one ion of the class consisting of anions and cations selected from the lyotropic series and of greater activity in said series-than barium and chloride, the density ratio of said light-polarizing means being substantially higher than that of light-polarizing means formed by a similar process, but which is devoid of said step
  • a process for producing dichroic dye images the steps of providing, a layer of a dyeablematerial comprising a transparent, linear, high molecular weight, hydroxylcontaining, vinyl polymer which has the molecules thereof in a substantially. oriented condition and which con tainsa basic nitrogen-containing dye ,mordant therein,
  • each said layer of a hydroxyl-containing vinyl polymer is additionally subjected to the action of at least one electrolyte absorbed into said polymer at a time prior to the printing of an image of said stereoscopic pair upon each of said layers, following which each of said layers is rinsed and dried, said solution of said electrolyte used in pretreating each said layer prior to the printing of a dichroic dye image thereupon being substantially similar to said solution of said electrolyte absorbed into each said layer after the dyeing thereof in that the ions of said electrolyte include at least one ion of the class consisting of anions and cations selected from the lyotropic series and of greater activity in said series than barium and chloride.
  • a light-polarizing product showing a high density ratio comprising a film of a molecularly oriented, transparent, linear, high molecular weight, hydroxyl-containing, vinyl polymer, a basic nitrogen-containing dye mordant distributed substantially uniformly throughout said film, and at least one dichroic direct cotton dye carried by at least a portion of said film to render said portion light-polarizing, said film having had imbibed thereinto, after the dyeing thereof with said dye, a solution of at least one electrolyte, the ions of which include at least one ion of the class consisting of anions and cations selected from the lyotropic series and of greater activity in said series than barium and chloride, whereby the density ratio of the light-polarizing portion of said product is substantially higher than that of a light polarizer formed, respectively, from a similar hydroxyl-containing vinyl polymer, a similar dye mordant and a similar dye but which has had no solution of an electrolyte imbibed thereinto.
  • each image of said stereoscopic image pair is a monochromatic dye image.
  • each image of said stereoscopic image pair is a multicolor dye image.
  • each image of said stereoscopic image pair is a multicolor image comprising cyan, magenta and yellow component images.
  • each said film comprises polyvinyl alcohol.
  • each of said pair of films has additionally had absorbed thereinto, prior to the printing thereon of one of said stereoscopic pair of light-polarizing dye images, a solution of an electrolyte, following which each said film has been rinsed and dried, said electrolyte solution being similar to that imbibed into said layer after the dyeing thereof in that the ions of each of said electrolyte solutions include at least one ion of the class consisting of anions and cations selected from the lyotropic series and of greater activity in said series than barium and chloride.

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Cited By (9)

* Cited by examiner, † Cited by third party
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US3241960A (en) * 1961-10-24 1966-03-22 American Optical Corp Method for making vectographs
US3244582A (en) * 1961-07-04 1966-04-05 Kuhl Georg Walter Light transmitting construction and process for its manufacture
US3249432A (en) * 1960-08-22 1966-05-03 Polaroid Corp Novel photographic processes
US3475248A (en) * 1965-12-06 1969-10-28 Du Pont Method of thermoplastic film manufacture
US3531351A (en) * 1967-05-01 1970-09-29 Polaroid Corp Preparation of light-polarizing film
US3545998A (en) * 1968-03-28 1970-12-08 Polaroid Corp Lower aliphatic alcohol treatment of light polarizing film
US3853675A (en) * 1970-12-30 1974-12-10 Rue T Int Ltd De Materials adapted to exhibit varying visual appearances
US20070202265A1 (en) * 2006-02-24 2007-08-30 Essilor International ( Compagnie Generale Generale D'optique) Process for Manufacturing a Polarized Poly(thio)urethane Optical Lens
US20090306293A1 (en) * 2007-02-09 2009-12-10 Seung Ae Kim Polarizer Having Excellent Durability, Polarizing Plate and Methods of Producing the Polarizer and the Polarizing Plate

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US2236061A (en) * 1937-05-27 1941-03-25 Du Pont Method of making films, threads, and the like
US2359735A (en) * 1939-12-16 1944-10-10 American Cyanamid Co Dyeing of polyvinyl halide-acetate copolymer fibers and fabrics
US2373035A (en) * 1939-05-27 1945-04-03 Polaroid Corp Light polarizing image and process of manufacture
US2387914A (en) * 1944-02-17 1945-10-30 Technicolor Motion Picture Imbibition printing
US2445555A (en) * 1945-04-16 1948-07-20 Polaroid Corp Light-polarizing polyvinyl sheet containing polyvinyl compoundboric acid complex
US2454515A (en) * 1938-10-29 1948-11-23 Polaroid Corp Light-polarizing sheet of molecularly oriented transparent linear high polymer dyed with dichroic substance and process of manufacture
US2612079A (en) * 1948-05-12 1952-09-30 American Optical Corp Process of making light polarizers

Patent Citations (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2236061A (en) * 1937-05-27 1941-03-25 Du Pont Method of making films, threads, and the like
US2454515A (en) * 1938-10-29 1948-11-23 Polaroid Corp Light-polarizing sheet of molecularly oriented transparent linear high polymer dyed with dichroic substance and process of manufacture
US2373035A (en) * 1939-05-27 1945-04-03 Polaroid Corp Light polarizing image and process of manufacture
US2359735A (en) * 1939-12-16 1944-10-10 American Cyanamid Co Dyeing of polyvinyl halide-acetate copolymer fibers and fabrics
US2387914A (en) * 1944-02-17 1945-10-30 Technicolor Motion Picture Imbibition printing
US2445555A (en) * 1945-04-16 1948-07-20 Polaroid Corp Light-polarizing polyvinyl sheet containing polyvinyl compoundboric acid complex
US2612079A (en) * 1948-05-12 1952-09-30 American Optical Corp Process of making light polarizers

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3249432A (en) * 1960-08-22 1966-05-03 Polaroid Corp Novel photographic processes
US3244582A (en) * 1961-07-04 1966-04-05 Kuhl Georg Walter Light transmitting construction and process for its manufacture
US3241960A (en) * 1961-10-24 1966-03-22 American Optical Corp Method for making vectographs
US3475248A (en) * 1965-12-06 1969-10-28 Du Pont Method of thermoplastic film manufacture
US3531351A (en) * 1967-05-01 1970-09-29 Polaroid Corp Preparation of light-polarizing film
US3545998A (en) * 1968-03-28 1970-12-08 Polaroid Corp Lower aliphatic alcohol treatment of light polarizing film
US3853675A (en) * 1970-12-30 1974-12-10 Rue T Int Ltd De Materials adapted to exhibit varying visual appearances
US20070202265A1 (en) * 2006-02-24 2007-08-30 Essilor International ( Compagnie Generale Generale D'optique) Process for Manufacturing a Polarized Poly(thio)urethane Optical Lens
US20090306293A1 (en) * 2007-02-09 2009-12-10 Seung Ae Kim Polarizer Having Excellent Durability, Polarizing Plate and Methods of Producing the Polarizer and the Polarizing Plate
US8609764B2 (en) * 2007-02-09 2013-12-17 Lg Chem, Ltd. Polarizer having excellent durability, polarizing plate and methods of producing the polarizer and the polarizing plate

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