WO1996009125A1 - Procede pour rendre reflechissants des films transparents - Google Patents

Procede pour rendre reflechissants des films transparents Download PDF

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Publication number
WO1996009125A1
WO1996009125A1 PCT/US1995/011957 US9511957W WO9609125A1 WO 1996009125 A1 WO1996009125 A1 WO 1996009125A1 US 9511957 W US9511957 W US 9511957W WO 9609125 A1 WO9609125 A1 WO 9609125A1
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WO
WIPO (PCT)
Prior art keywords
zns
film
transfer
layer
thickness
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US1995/011957
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English (en)
Inventor
Peter Cueli
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Crown Roll Leaf Inc
Original Assignee
Crown Roll Leaf Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Crown Roll Leaf Inc filed Critical Crown Roll Leaf Inc
Publication of WO1996009125A1 publication Critical patent/WO1996009125A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/24—Vacuum evaporation
    • C23C14/26—Vacuum evaporation by resistance or inductive heating of the source
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/06—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the coating material
    • C23C14/0623—Sulfides, selenides or tellurides
    • C23C14/0629—Sulfides, selenides or tellurides of zinc, cadmium or mercury
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/56—Apparatus specially adapted for continuous coating; Arrangements for maintaining the vacuum, e.g. vacuum locks
    • C23C14/562—Apparatus specially adapted for continuous coating; Arrangements for maintaining the vacuum, e.g. vacuum locks for coating elongated substrates
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/02—Details of features involved during the holographic process; Replication of holograms without interference recording
    • G03H1/0276—Replicating a master hologram without interference recording
    • G03H1/028—Replicating a master hologram without interference recording by embossing
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/0005—Adaptation of holography to specific applications
    • G03H2001/0055—Adaptation of holography to specific applications in advertising or decorative art

Definitions

  • the present invention relates to a method for making transparent
  • reflective films and products incorporating them such as, diffraction gratings, and, more particularly, to a method for applying a transparent, colorless,
  • transparent or semi-transparent films that are reflective when viewed at selected orientations. It should be noted at the outset that even very clear glass or plastic attenuates light to some degree and, in this respect, is not completely transparent. Similarly, a transparent, reflective film which appears transparent at some viewing angles and reflective at others is not completely transparent, but rather, semi-transparent.
  • transparent is intended to describe a condition that is perceived by the human eye, viz., the appearance of transparency and includes semi-transparency and transparency at selected viewing angles.
  • reflective films can be employed as a decorative wrapping paper or as product packaging, as well as for forming diffraction gratings and holograms.
  • Holograms have recently come into wide usage as decorative indicia due to the hologram's unique capacity to reconstruct three-dimensional images from a seemingly two-dimensional surface. Holograms are thus readily identifiable as such, even upon casual inspection, since non-holographic indicia do not create a three-dimensional virtual image. Diffraction gratings have also become popular given their capacity to embody bright, colorful, light-reflective patterns,
  • Diffraction grating patterns also have attributes that render them more suitable than holograms for decorative
  • Diffraction grating patterns are also suitable for viewing in diffuse lighting conditions, as opposed to illumination by a point source. These qualities have given rise to use of diffraction grating patterns on decorative sheet material, such as, gift wrapping and on other decorated products like greeting cards. It is, on the whole, less demanding to produce an acceptable diffraction grating patterned material than to produce acceptable holograms. This is due to the narrow optimum viewing parameters of holograms and to the graphic content of a hologram, viz., a 3D depiction of a real object or artwork.
  • a diffraction grating pattern may be an arbitrary 2D pattern with a very wide range of viewing angles. Because a hologram is visible in its entirety from a particular optimum viewing angle, the integrity (or lack thereof) of the pattern is immediately evident. In contrast, diffraction grating patterns are often partially viewable from many different perspectives. Accordingly, it may be harder to discern defects in diffraction grating patterns than in holograms.
  • the visual effect of holograms and diffraction gratings derive from substantially the same optical principles, however. While the respective methods for origination differ, the mass production of embossed holograms and diffraction gratings is essentially the same. This production method could be briefly described as embossing a
  • holograms or “diffraction gratings” that follow in this application are intended to refer to both unless specifically indicated otherwise.
  • Apparatus utilized to fabricate holograms and diffraction gratings are typically complex, expensive and require sophisticated personnel to operate. Accordingly, their production is a specialty which is engaged in by companies which are suitably equipped through substantial capital expenditures. Since holograms and diffraction gratings require sophisticated apparatus to make and have readily identifiable, visually perceptible attributes, they have become
  • holograms In the field of security holograms, it has been recognized that in order to utilize a distributed hologram over the surface of a substrate and, at the same time, avoid obscuring other indicia which appears thereon, the hologram must be at least partially transparent.
  • Mass-produced holograms are typically phase holograms embossed in optically clear thermoplastic film as a microtexture which is overcoated with a reflective layer.
  • an embossed phase hologram carrying a relief pattern on one surface having no reflective coating thereon. Instead, an air gap is maintained between the hologram and a supporting substrate to cause incident light to be reflected from the surface relief pattern. Since the refractive index of air is significantly
  • the aluminum dots are discontinuous, a viewer may view through the hologram, i.e., between the dots, to see indicia appearing below the discontinuous holographic pattern.
  • U.S. Patent No. 3,578,845 to Brooks suggests that the reflective layers of a hologram may be rendered partially transparent by varying the thickness thereof, namely, from 100 angstroms to 5 microns. Such a thin reflective layer achieves the desired transparency, as well as reflectivity.
  • playback tape incorporating a holographic relief pattern embossed thereon with a coating having an index of refraction which is different from that of the tape.
  • Hannan et al. suggests that the coating should be essentially transparent, sets forth a few examples and suggests general methods for applying the coating.
  • U.S. Patent No. 4,856,857 to Takeuchi et al. describes a transparent holographic effect enhancing layer laminated to a transparent hologram forming layer. The two layers have differing refractive index.
  • Takeuchi et al. suggests numerous potential materials for the hologram forming layer and for the holographic effect enhancing layer including ZnS and teaches that the effect enhancing layer can be applied by vapor deposition, sputtering, reactive sputtering, ion plating, electroplating and coating methods in general.
  • the foregoing techniques and products do, however, suffer from certain drawbacks. For instance, the air-gap phase hologram concept requires
  • the present application envisions the use of transparent/semi-transparent diffraction gratings for decorative and security purposes, e.g., on wrapping paper which permit visualization of an item wrapped therein while still exhibiting the decorative effect of the grating.
  • the present invention also contemplates a method for
  • a crucible with ZnS solids placing the crucible in a vacuum deposition chamber having a supply roll of the polymer film and a take-up roll; and evacuating the deposition chamber.
  • the crucible is then heated by induction to sublimate the ZnS solids into a vapor. After the ZnS vapor is present, the transfer of the film
  • the thickness of the ZnS layer is monitored and the rate of transfer of the film is adjusted to control the thickness of the ZnS layer.
  • FIG. 1 is an enlarged cross-sectional view of a film coated with a reflective layer and fabricated in accordance with an exemplary embodiment of the present invention.
  • FIG. 2 is a schematic depiction of a vacuum vapor deposition chamber during the coating of a microembossed substrate with a reflective
  • FIG. 1 shows a laminate 5 formed from a polymer film 10, such
  • the reflective layer 12 is a coating, e.g., ZnS, having a refractive index which differs from that of the film 10.
  • the film 10 is embossed along a portion 14 of the surface in contact with layer 12. This embossed portion 14 may represent either a holographic or diffraction grating micro-texture. Another portion 16 of
  • FIG. 1 thus illustrates that the present inventive method may be used to coat various types of films to yield various products, e.g., smooth films and films embossed with holograms and diffraction gratings.
  • the laminate 5 is substantially clear but reflective at selected viewing angles. As a result, the laminate 5 can function as a reflective wrap, diffraction grating or hologram while remaining transparent.
  • transparent diffraction gratings Assuming a commercially feasible method for producing transparent diffraction gratings at modest cost, they can be utilized for material intensive decorative purposes, e.g., in signage, for wrapping paper, or in product packaging, as well as for security purposes. Similarly, transparent, reflective polymer sheeting (webbing) without diffraction grating or holographic microtextures may be employed for wrapping, packaging and decorating. Having set forth certain of the functional attributes of a coated film in accordance with the present invention, the methods for fabricating it shall now be discussed with reference to FIG. 2.
  • the present invention employs a reflective layer 12 formed from tin tungsten oxide (SnWO4), zinc sulfide (ZnS), or a mixture of the two.
  • tin tungsten oxide SnWO4
  • ZnS zinc sulfide
  • the ratio can be about 80 % to about 99% by weight of tin tungsten oxide and about 20% to about 1% by weight of zinc sulfide, it being understood that the percentages of the two components of the resulting mixture should total 100%.
  • a suitable and preferred ratio is 90% by weight of tin tungsten oxide and 10% by weight of zinc sulfide.
  • FIG. 2 shows a vacuum deposition chamber 18 containing a web feed roll 20, a first guide roll 22, a second guide roll 24 and a take-up roll 26.
  • Vacuum deposition chambers of this type are commercially available.
  • a reflective layer 12 of zinc sulfide may be formed on a web 10 of embossable film, e.g., MYLAR brand polyester, as it is advanced through the vacuum deposition chamber 18 at a vacuum of
  • the web 10 of polymeric material which may be smooth or embossed with a holographic or diffraction grating microtexture, passes in close proximity to a carbon crucible 28 containing cubes or pills 30 of ZnS.
  • the crucible 28 and the ZnS cubes 30 are heated to approximate temperatures of 1200 and 1000 degrees C, respectively, by an induction heater 32.
  • Coating the web in accordance with the present invention's parameters results in a layer of zinc sulfide having a thickness in a range of from about 1,000 angstroms to about 2,000 angstroms.
  • the deposition chamber 18 is provided with an observation port
  • An aspect of the present invention is the recognition that a web with a suitable thickness of ZnS has a different appearance from one which has an inappropriate thickness. More specifically, the thickness of the ZnS coating effects the color of the web due to thin film interference. At thicknesses below 1,000 Angstroms, there is inadequate reflectivity. For thicknesses of 1,000
  • the web appears reflective but almost colorless. Beyond 2,000 Angstroms, the web exhibits the colors of the rainbow with the particular color depending upon the thickness of the ZnS coating. This coloring effect is particularly noticeable when the web being coated, e.g., as shown in FIG. 2, is illuminated by a light source 36 such as a white fluorescent tube.
  • a light source 36 such as a white fluorescent tube.
  • the web which has been coated with a reflective layer, has a mirrored appearance.
  • the operator can visualize the light 36, preferably a white fluorescent tube having a width approximating or exceeding that of the web, as a reflection in the mirrored web.
  • the reflected image of the fluorescent tube appears white.
  • the bulb appears colored, e.g., yellow or violet.
  • the coating process must be very precise. For example, it is usually preferable for the transparent reflective layer to be colorless as well as transparent reflective.
  • the present invention provides a means of achieving a reflective layer that is colorless by monitoring the thickness of the coating.
  • the present inventive method may be performed by first establishing the proper temperature of the induction crucibles (@ 1200 degrees Centigrade) that generates a sufficient rate of sublimation of the ZnS cubes 30 and resultant gas density to coat a web passing thereby at a commercially feasible rate of at least 60 ft./min. This temperature is maintained throughout the coating of the web.
  • the thickness of the ZnS coating is determined primarily by controlling the web speed over the sublimating compound. The proper coloration and ZnS thickness for the coated web can therefor be achieved
  • a densitometer 38 may be employed to monitor the coating process by electro-optically measuring the optical density or transmissivity of the coated web. Densitometers of this type can be obtained from Custom Fabrication & Services Co., Inc. of Bloomfield, Connecticut. Increasing the thickness of the ZnS coating decreases transparency and thus the densitometer may be used to measure the thickness of the coating by measuring how much light passes through the web. Any indication of excess thickness of the reflective coating signals that a compensating increase in web speed is required. Conversely, a high transparency indicates that the web speed should be decreased. With respect to ZnS coatings, it has been observed that densitometer instruments of this type are far more sensitive to light absorption
  • the form of the ZnS i.e., the size of the particles, the method for heating them, as well as, the temperature and the rate of web advance are all critical to successful commercial production. It should first be understood that in order to be commercially feasible, the costs of production of a product must be controlled. With respect to coating an embossed web with ZnS, the factors having a large impact on cost are throughput, waste and energy expended. In order to be commercially expedient, throughput must be at least 60 ft. per min. Each reduction in throughput results in a corresponding cost increase. Energy input is another large contributor to cost of a product.
  • the sublimation of ZnS requires a lot of "clean" and expensive energy, i.e., electrical power, it is essential that the duration of energy use be minimized.
  • the sublimation must be relatively even, i.e., if the vapor density fluctuates, the constantly moving web will be coated to varying
  • the form of the ZnS is important to the operation of the method
  • the degree of comminution effects the surface area sublimating, the rate of sublimation, the weight of the individual particles and their resultant stability when subjected to the expansion of gases resulting from sublimation.
  • the rate of sublimation is increased due to the small size of the individual particles and increased overall surface area, however, the small particles tend to pack together closely such that the sublimation occurring at lower levels in a charge generates gases that force the upper layer particles up and out of the crucible in which they are contained.
  • powdered ZnS blows itself out of the crucibles.
  • a much larger volume of ZnS must be sublimed as compared to a metal, such as Aluminum, for forming a reflective layer.
  • a metal such as Aluminum
  • approximately 6 kilograms of ZnS is required to coat a 24" wide X 15,000' roll of substrate web.
  • about 1 pound of Aluminum is required to coat a similar web with Aluminum metal.
  • the quality of the reflective layer is far less critical for smooth reflective films and diffraction gratings than for holograms due to the unitary, integrated composition of a hologram as compared to a fragmented diffraction grating pattern or the absence of a pattern. This has an impact on the degree of precision of coating thickness required for the respective products. In general, however, holograms diffraction gratings and unpatterned film are maximized by a ZnS thickness of about 2,000 Angstroms.
  • An important aspect of the present inventive method is to deposit
  • Optimal thickness is that thickness which is minimum while still providing acceptable optical properties. It has been observed that coating thicknesses in excess of 2,000 Angstroms exhibit color rather than being colorless. Thicker layers do have the beneficial effect of
  • a thickness between 1,000 and 2,000 angstroms is optimal to provide acceptable reflective effects without a significant loss of transparency. Furthermore, a thickness of about 2,000 angstroms is achievable in accordance with the foregoing technique at a web rate of about 500 ft./min. and an energy
  • a reflective layer 32 may be formed in accordance with the above-described process from tin tungsten oxide on a web of embossable film, e.g., MYLAR, by advancing the web through a vacuum deposition chamber held at a vacuum of approximately 10 '5 Torr and at a feed rate in a range of from about 50 feet/minute to about 250 feet/minute.
  • the tin tungsten oxide is
  • a reflective layer 32 may be formed in accordance with the above described process from a mixture of tin tungsten oxide and zinc sulfide, on a web of embossable film, e.g., MYLAR, by advancing it through a vacuum deposition chamber at a vacuum of approximately 10 '5 Torr and at a feed rate
  • the zinc sulfide/tin tungsten oxide mix is evaporated onto the mylar film at a temperature of approximately 1000 degrees C.
  • Tin tungsten oxide Tin tungsten oxide, zinc sulfide, and mixtures thereof are
  • diffraction gratings, transparent reflective film and phase holograms fabricated in accordance with the present invention may be mass produced rapidly and without extensive processing, environmental
  • the present invention provides a method for producing transparent reflective films, holograms and diffraction grating materials on a commercially feasible basis, as can be appreciated from the following example.
  • a roll of polyester material having dimensions 24 inches by 15,000 ft. was loaded onto the feed roll of a induction vapor deposition chamber

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Laminated Bodies (AREA)

Abstract

Un procédé pour rendre refléchissants des films transparents (5) consiste à appliquer sur un film de polymère (10) du ZnS (12), à partir d'un ensemble de creusets (30) en carbone contenant des cubes ou des pastilles de ZnS. Les creusets (30) sont chauffés par induction, pour former un dépôt sur le film dans une chambre (18) sous vide renfermant une bobine d'alimentation (20) en film de polymère et une bobine de réception (26). Les cubes de ZnS subissent une sublimation à une vitesse adaptée à la vitesse de défilement du film pour assurer une épaisseur de revêtement sur les films incolores de 1000 à 2000 Å. L'épaisseur de la couche de ZnS sur le film est surveillée par observation visuelle de la couleur ou par la transmissivité, et la vitesse de défilement du film est adaptée à l'épaisseur souhaitée pour la couche de ZnS.
PCT/US1995/011957 1994-09-22 1995-09-19 Procede pour rendre reflechissants des films transparents Ceased WO1996009125A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US31043594A 1994-09-22 1994-09-22
US08/310,435 1994-09-22

Publications (1)

Publication Number Publication Date
WO1996009125A1 true WO1996009125A1 (fr) 1996-03-28

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PCT/US1995/011957 Ceased WO1996009125A1 (fr) 1994-09-22 1995-09-19 Procede pour rendre reflechissants des films transparents

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109468591A (zh) * 2019-01-10 2019-03-15 合肥市辉耀真空材料有限责任公司 一种真空蒸镀工艺制备幻彩反光膜的方法

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4045125A (en) * 1974-06-27 1977-08-30 Etat Francias Band filters for use in protective glasses
US5107791A (en) * 1987-12-17 1992-04-28 Toyo Ink Manufacturing Co., Ltd. Process for the manufacture of deposition films and apparatus therefor
US5184848A (en) * 1989-08-31 1993-02-09 Dai Nippon Insatsu Kabushiki Kaisha Hologram calendar

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4045125A (en) * 1974-06-27 1977-08-30 Etat Francias Band filters for use in protective glasses
US5107791A (en) * 1987-12-17 1992-04-28 Toyo Ink Manufacturing Co., Ltd. Process for the manufacture of deposition films and apparatus therefor
US5184848A (en) * 1989-08-31 1993-02-09 Dai Nippon Insatsu Kabushiki Kaisha Hologram calendar

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109468591A (zh) * 2019-01-10 2019-03-15 合肥市辉耀真空材料有限责任公司 一种真空蒸镀工艺制备幻彩反光膜的方法

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