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WO1988003667A1 - Materiau d'enregistrement comprenant un complexe d'azide metallique et des explosifs colorant-azide - Google Patents

Materiau d'enregistrement comprenant un complexe d'azide metallique et des explosifs colorant-azide Download PDF

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Publication number
WO1988003667A1
WO1988003667A1 PCT/US1987/002904 US8702904W WO8803667A1 WO 1988003667 A1 WO1988003667 A1 WO 1988003667A1 US 8702904 W US8702904 W US 8702904W WO 8803667 A1 WO8803667 A1 WO 8803667A1
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Prior art keywords
explosive
medium
dye
complex
azide
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PCT/US1987/002904
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English (en)
Inventor
Paul C. P. Thomson
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Optical Recording Corp
COHN RONALD D
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Optical Recording Corp
COHN RONALD D
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Publication of WO1988003667A1 publication Critical patent/WO1988003667A1/fr
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    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
    • G11B7/244—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising organic materials only
    • G—PHYSICS
    • G11—INFORMATION STORAGE
    • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
    • G11B7/00—Recording or reproducing by optical means, e.g. recording using a thermal beam of optical radiation by modifying optical properties or the physical structure, reproducing using an optical beam at lower power by sensing optical properties; Record carriers therefor
    • G11B7/24—Record carriers characterised by shape, structure or physical properties, or by the selection of the material
    • G11B7/241—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material
    • G11B7/242—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers
    • G11B7/244—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising organic materials only
    • G11B7/249—Record carriers characterised by shape, structure or physical properties, or by the selection of the material characterised by the selection of the material of recording layers comprising organic materials only containing organometallic compounds

Definitions

  • the present invention relates to the recording of binary information on laser recording media. More particularly, the invention relates to laser recording media containing thermal energy amplifying substances and the preparation of such media.
  • Some recording media including those that contain chemical dyes which change color in response to heat or light and those that are thin films or tapes which are perforated by pulses of intense laser light, do not require chemical development.
  • high-intensity lasers in order to generate enough energy to make recording marks.
  • the production of high-intensity laser light is much more expensive than the production of lower intensity laser light. It is, therefore, desirable to provide a recording medium which will record information when subjected to comparatively low intnnsity laser light.
  • Roberts refers to a recording film that comprises a substrate of an organic material coated with a material having heat-absorbing characteristics, such as carbon black particles, dispersed in a self-oxidizing binder such as nitrocellulose.
  • a material having heat-absorbing characteristics such as carbon black particles
  • nitrocellulose a self-oxidizing binder
  • the Roberts medium has a grain structure. This limits the resolution of the medium. Also, Roberts' use of a self-oxidizing binder further limits resolution and presents other problems.
  • Nitrocellulose is a poorly defined substance formed by treating cellulose with mixtures of nitric and sulfuric acid. Widely different nitrocellulose products are obtained by varying the source of cellulose, strengths of acids, temperature, time of reaction, and the acid cellulose ratio. Exact reproduction of a particular nitrocellulose has proven to be difficult due to the numerous variables in the reaction process. Thus, a medium of the type described by Roberts would be difficult to manufacture in commercial quantities due to uniformity and other quality control problems. This is undesirable as it is important that the media obtained from different batches possess a constant sensitivity to laser light in order to ensure that the spots generated are of uniform size and can be spaced closely to achieve maximum data density.
  • the described recording medium is a polymer material containing particles of reactant substance.
  • reactant particles are made by combining a metal reducing agent with an oxidizing agent such as barium chromate to form a thermite type mixture.
  • the reactant particles react exothermically upon exposure to laser light of sufficient intensity. This reaction chars the polymer material, thus creating dark areas which can be read by an optical digital scanner.
  • a polymer binder is charred.
  • the reactant particles utilized in Moore et al. will produce a grain structure similar to that of the Roberts media, thus limiting resolution.
  • Rubner U.S. Patent 4,287,294, discussed in context in more detail below, describes a photographic medium in which organic azides are used as photo-initiators.
  • de Bont et al. U.S. Patent 4,230,939, describes an information-recording element having a dye-containing auxiliary layer. It provides a transparent substrate, an auxiliary layer provided on the substrate, and a laser-reflective information recording layer provided on the auxiliary layer.
  • This auxiliary layer or activating layer includes a laser light-absorbing dye.
  • laser light is incident on and passes through the transparent substrate, traverses and is partly absorbed by the auxiliary layer, is then reflected against and partially absorbed by the information recording layer, again traverses and is partly absorbed by the auxiliary layer and ultimately leaves the element on the side of the substrate.
  • the resultant temperature increases in the laser incident areas of the auxiliary layer and the information recording layer cause melting and hole formation in the information recording layer and in the auxiliary layer.
  • the auxiliary layer may also include an endothermal material (i.e. a material capable of conversion via exothermal decomposition into thermal energy and pressure build-up) namely a polymeric endothermal material such as nitrocellulose or nitroglycerine-nitrocellulose mixtures which are used as explosive binders for the dye in the auxiliary layer.
  • Picrates for example the picric acid salt of the dye used in the auxiliary layer, are also suggested. However, none is specifically exemplified.
  • a recording medium matrix with a photosensitive material that includes a selected metal azide complex explosive material and a compatible, appropriately light absorptive dye.
  • the explosive material exhibits a suitably rapid exothermic decomposition at conditions achievable in localized areas under laser radiation of a wavelength and intensity commonly encountered in optical recording equipment, to cause ablation of the photosensitive layer and hence leave optically detectable indicia.
  • the material also has the added benefit that the metal azide complex is more readily solubilized, and is solubilized to a greater extent, than a discrete azide compound.
  • the recording medium includes an appropriately light absorptive dye compound having an explosive group chemically associated therewith, bonded to the dye molecule ionically or covalently, optionally through a transition metal azide complex.
  • the explosive group is an azido group.
  • Dye compounds having explosive azido groups ionically bonded thereto, i.e. having azido counter-ions (N 3 -) can be prepared from available ionic dyes, by replacement of their normal anions (commonly but not exclusively halogen, perchlorate, etc.) with azide anion by processes of ion exchange, in a manner which does not significantly change the absorption characteristics of the dye molecule.
  • Dye compounds having explosive azido groups non-ionically bonded thereto can be prepared from available dyes containing in their molecular structure replaceable chemical groups non-ionically bonded to the dye molecule skeleton, by chemical substitution processes which do not significantly change the absorption characteristics of the dye molecule.
  • Dye compounds having a transition metal azide compound bound thereto to provide the explosive group in the molecule of the complex may be prepared by reaction of an amino group containing dye with a transition metal azide, e.g. cupric azide. In each case, in use, the light radiation absorbed by the dye is converted by the dye to thermal energy which causes the chemically associated explosive group to decompose exothermically, to create optically detectable indicia in the recording media .
  • a significant advantage of this embodiment is that the dye compound having explosive azide compounds bonded thereto is more readily solubilized and is solubilized to a greater extent than discrete azide compounds and dye mixtures.
  • a solubility improver which is a substance to enhance the compatibility of metal azide and dye and which by its nature reduces the inner sensibility of the recording medium, is not required.
  • One particularly preferred example of explosive materials containing suitable materials for use in the present invention is transition metal azide complexes, especially those having explosion temperatures above about 100° C and below about 350° C, and which are capable of giving significant energy output on explosive decomposition.
  • the photosensitive material suitably includes a molecular dispersion of a metal azide complex.
  • a matrix proves to be a very precise recording medium.
  • the additional heat energy and gases liberated during the reaction are sufficient to create a void or hole in the photosensitive material.
  • the dye portion of such molecule absorbs the light energy and is heated, to cause the explosive groups in the heated volume of the medium and associated with the dye molecule predictably to react exothermically, and thereby create a void or hole in the photosensitive material.
  • a particularly advantageous medium according to the present invention includes a substrate material which is coated with a photosensitive material, and a protective transparent covering which overlies the photosensitive material.
  • the photosensitive material is a solid solution which includes a metal azide complex and a dye. When a beam of light is directed at such a medium, light energy is absorbed by the dye which in turn transfers thermal energy to the azide. The azide explosively reacts, liberating heat and nitrogen and creates a void or a hole in the photosensitive material.
  • the void has different optical characteristics than the surrounding material which contains the dye and thus can be read by an optical scanner (i.e. the void may be a dark spot on a light background, or for a reflective substrate, a light spot on a dark background).
  • the photosensitive material of the invention thus does not utilize "grains” but rather includes homogeneously dispersed molecules of the metal azide and the absorbing dye. Because there are no "grains", the medium has very high resolution.
  • Some patents describe photographic media which form an image by the decomposition of organic azides. The images are formed by mechanisms that do not utilize heat released during decomposition.
  • the metal azide organic complexes of the present invention have different characteristics from uncomplexed metal azides. Certain organic azides have been previously used as cross-linking agents, dye couplers, or initiators for polymerization. For example, in U.S. Patent No. 4,287,294 of Rubner, organic azides are used as photo-initiators.
  • the organic azide in the Rubner patent absorbs the radiant energy and transfers this energy to an olefxnically unsaturated polymer which initiates further polymerization or cross-linking.
  • This is distinct from the present invention in which a void is created by heat and gas given off as a metal azide reacts exothermically.
  • the photosensitive material in the present invention is ablated, in contrast with the charring of the polymeric binder which occurs in the method of Moore et al.
  • One object of this invention is to provide a digital recording medium which is able to utilize comparatively low intensity laser light as a recording source.
  • Another object of the invention is to provide a digital recording medium which, after being recorded upon, will provide high resolution when read by an optical scanner.
  • Another object of this invention is to provide a digital recording medium which, after being recorded upon, will provide a high signal to noise ratio when read by an optical read-out device.
  • FIG. 1 is a block diagram of an analog to digital optical recording system capable of producing a permanent record on the recording medium of the present invention
  • FIG.s 2 and 3 are side, cross section views of recording media according to the present invention.
  • a typical device for recording a binary data pattern by means of a radiant energy source, particularly a pulsed light source.
  • the system includes a recorder unit 10 having its input connected to an audio-visual analog signal source 12, such as a microphone or television camera.
  • This analog input signal 23 is applied to the input of an analog-to-digital signal converter 24 provided in the recorder unit 10 and which produces a digitally encoded electrical output signal 26.
  • the output of the analog-to-digital signal converter 24 may be directly connected to an electrical optical digital signal recorder 28 through an amplifier 29 if it is desired to record the digital signal in real time simultaneously as it is generated. However, it may be desirable temporarily to store the digital signal 26 on the magnetic tape or other memory device of a digital computer 30 and to record such signals later at a more convenient time.
  • the electrical to optical digital signal recorder 28 converts the digital electrical signal into a digital light signal and records such light signal by scanning a pulsed light beam 40 of small spot size on a photosensitive recording medium to produce a track of digitally encoded spots which can be less than one micron in diameter.
  • the spots are transparent in an opaque background, thus providing the ones and zeros of a binary code.
  • the recording medium is supported, in a fashion which may be conventional, for movement in a path perpendicular to the optical axis and is mechanically coupled to a recording medium positioning mechanism 44 adapted for moving the medium to produce the track of digitally encoded spots.
  • the recording medium positioning mechanism 44 may include a drive motor (not shown) which is energized selectively in response to signals transmitted by the optical digital signal recorder 28.
  • the recording medium 42 of the present invention includes a matrix interspersed with one or more explosives such as metal azide complexes or dye-azide compounds, which are stable when exposed to light of first level of intensity, but which react exothermically when exposed to light at a second, higher level of intensity.
  • explosives such as metal azide complexes or dye-azide compounds
  • such a recording medium is shown as an active or recording layer 50 of photosensitive material, normally including a metal azide complex and a dye, or a dye-azide compound, on a smooth surface of a substantially transparent substrate 54. Binders are not necessary when using dye-azide compounds.
  • the active layer 50 can be a composite of two or more layers with a complex metal azide and dye in separate layers of the composite.
  • a protective layer 56 may, optionally, be provided over the active layer 50 so that the protective layer 56 and substrate 54 protect opposite sides of the active layer from dust and other physical contaminants.
  • a thin reflective coating could be included on a surface 58 of the active layer 50 to reflect incident radiation 40a back into the active layer.
  • FIG. 3 shows a closely related embodiment for use with a beam 40b of incident radiation directed toward an active layer 60 rather than a substrate layer 64.
  • any protective layer 66 would be substantially transparent.
  • a reflective layer it would best be located between the active layer 60 and the substrate 64.
  • one or more subbing layers can be provided between the substrate and the active layer or between the protective layer and the active layer for the purposes described below. Such subbing layers must be substantially transparent if they are located in. the path of the incident beam.
  • a recording medium comprises a photosensitive layer which includes an explosive material, particularly a metal azide complex, and a dye.
  • the dye absorbs laser light, efficiently converting the light to heat which is transferred to the metal azide complex.
  • the metal azide complex reacts exothermically, when initiated by heat from the dye, to amplify the energy from an incident radiation beam.
  • the explosive material is preferably one which gives a high velocity of escaping gases on decomposition.
  • the exothermal reaction of the metal azide complex causes a heat build up and the formation of a visible mark or spot in the medium.
  • Cupric, lead, and silver azide complexes are well suited since they react highly exotherically and yet can easily be incorporated in a recording medium.
  • Transition metal azides complexes, especially cupric azide complexes, constitute the most preferred class of explosive compounds for use in this embodiment of the present invention.
  • the medium may be formed by depositing a layer containing the metal azide complex on a substrate material from a solution thereof followed by spin-drying. Alternatively. the metal azide complex may be applied directly by vapor deposition.
  • a typical medium according to the invention will have an active layer of photosensitive material that is 0.05-2.0, preferably 0.05-0.15 microns thick.
  • the metal azides used in this embodiment of the present invention are explosive complexes of such metal azides.
  • the use of such explosive complexes shows significant advantages over the use of the metal azide itself in many instances. It can adjust the explosion temperatures into the desired range of 100-350°C (preferably 150-250°C). Most importantly, however, it permits adjustment and suitable arrangement of the solubility of the explosive material, in desired solvents, in which the selected dye is also soluble, to allow ease and safety of manufacture of these materials by deposition of the active layer on the substrate from solution.
  • Transition metal azide compounds will form complexes with chemical groups (ligands) containing atoms having one or more spare electron pairs.
  • ligands chemical groups
  • a suitably explosive metal azide complex may be formed.
  • not all amine ligand metal azide complexes produce suitably explosive materials.
  • the most preferred metal azide for use in the complexes in the compositions of the present invention is cupric azide
  • the suitably explosive complexes will be further discussed and exemplified with reference to cupric azide complexes, but it is to be understood that in many cases analogous complexes with other transition metal azides, particularly lead azide and silver azide, can be formed.
  • cupric azide forms a variety of complexes with nitrogen containing ligands, it is convenient to divide such complexes into two general classes, namely: non-ionic, where the copper atom is complexed with two azide groups and one or two amine groups
  • non-ionic complexes of the general structure [Cu(N 3 ) 2 (Amine) 2 ] suitable for use in the present invention are:
  • di-(methylamine) diazidocopper 180-190 di(n-propylamine) " " 187 di(ethylenediamine) " " 210 di(pyridine) " " 205 di(3-methylpyridine) " “ 207-215 di(2,6-dimethylpyridine) " 202-203 di(2,4,6-trimethylpyridine) " 198-202 di(iso-quinoline) " " 197-200
  • non-ionic complexes of the general structure [Cu(N 3 ) 2 (Amine)] suitable for use in the present invention are: Complex Explosion Temperature °C
  • Examples of ionic complexes of the general structure [Cu(N 3 ) 4 ] 2- [Amine H+ ]2 suitable for use in the present invention are: Complex Explosion Temperature °C
  • di-(dimethylammonium) tetraazido cuprate 210 di-(N-butylammonium) tetraazido cuprate 178-180 di-(iso-butylammonium) tetraazido cuprate 203 di-(piperidinium) tetraazido cuprate 200-205
  • Examples of ionic complexes of the general structure [Cu(N 3 ) 3 ]- [Amine H + ] suitable for use in the present invention are:
  • Examples of ionic complexes of the general structure [(N 3 ) 2 Cu(N 3 )Cu(N 3 ) 2 ]- [Amine H] + suitable for use in the present invention are:
  • a further class of suitable explosives is the cobalt and nickel hydrazine complexes, for example cobalt azide hydrazine complex of formula:
  • an explosive material should be a primary explosive as opposed to a secondary explosive, and should have an explosion temperature in the approximate range 100°C-350°C, and preferably 150°C-250°C. It should have a reasonable degree of solubility in at least one organic or inorganic solvent, preferably an oxygenated organic solvent. It should be capable of generating significant amounts of heat on decomposition.
  • the energy supplied by the incident laser radiation on making the optical record should be at least doubled by the thermal decomposition or explosion of the explosive material, and preferably is increased by at least 10 fold. It is further preferred that the granularity of the explosive material, and all other materials, in the photosensitive layer should be small, preferably less than 0.1 micron, to provide images of high optical resolution.
  • the photosensitive layer will also include a dye to facilitate absorption of energy from the energy source and conversion of the radiant energy into thermal energy.
  • the dye should be selected for its ability to absorb energy.
  • the dye In the case of a medium to be written by a laser beam, the dye should be selected to absorb light at the wavelength of the irradiating light. The dye efficiently absorbs the incident radiation of the laser, and converts the radiant energy to thermal energy to trigger the decomposition of the explosive material.
  • the recording media in accordance with the present invention, can be used in conjunction with light radiation in the infrared, visible or ultraviolet regions, emanating from suitable laser sources emitting in those regions. It is only necessary to choose a dye which has strong absorption characteristics at the wavelength of the chosen laser radiation. Suitable such dyes are known for use with laser radiation in the ultraviolet (250-350 nm) range, the visible (350-750 nm range) and the infrared (750-1150 nm) range.
  • a large number of dyes are suitable for use in conjunction with the metal azide recording medium. Those dyes which efficiently absorb the irradiating light and are soluble in suitable solvents are ideal. It is preferable to choose an explosive material and a dye which are significantly soluble in the same solvent or in mutually compatible organic solvents.
  • Useful dyes will be readily determinable by those skilled in the art, bearing in mind the wavelength of the selected laser for recording purposes. Identification of available dyes by their chemical class and structure, along with their radiation absorption characteristics, can be made from the available scientific literature.
  • the dyes erythrosin, erythrosin B, sudan III, rhodamine 6G and rose bengal are examples of suitable dyes.
  • useful dyes for the present invention will be found among the infrared dyes of the polymethine class, the squarylium class, the quinone class, and the metal complex class.
  • dicarbocyanines and tricarbocyanines are particularly preferred.
  • infrared dyes for use in the present invention, in connection with infrared low-intensity laser radiation sources (750-1100 nm):
  • HITC iodide or perchlorate
  • Squarylium dyes for example:
  • the chosen dye contains one or more amine groups
  • it may be chemically bonded- to the transition metal azide compound, so that the dye functions as the ligand of the complex.
  • the explosive group is part of the same molecule as the dye with consequent ease of energy transfer there between. Examples of such complexes are discussed below.
  • the photosensitive material may be formed to include the dye in at least two ways.
  • the metal azide complex and dye can be applied as separate, but adjacent layers or can be intimately mixed in a single layer.
  • a two layer system for example, one can first form a layer consisting of a metal azide complex dispersed in a polyethylene glycol binder.
  • a dye can then be applied as a coating using a 2% solution in methanol.
  • a solution of rose bengal can be poured on a metal azide complex layer, which is then spun at 1900 RPM until dry.
  • the resulting photosensitive material is a homogeneous red layer with an absorption coefficient of about 1.5 at 514 nm.
  • IR 125 dye has been used to form plates sensitive at 830 nm.
  • the IR 125 dye is made into a 2% solution in methanol and coated on a metal azide complex/binder layer. The coated material is spun at 1900 RPM until dry, and a clear green photosensitive material results. Such material has a broad absorption band covering the 750-850 nm region of the spectrum.
  • photosensitive material can be used to manufacture media which are sensitive to the output of semiconductor lasers operating in this wavelength region.
  • a medium would operate without a dye if the incident radiant energy was of a wavelength absorbed by the metal azide complex or by an adjacent binder material or subbing layer.
  • suitable choice of the organic ligand attached to the metal complex will facilitate absorption of the laser radiation, by having the organic ligand itself act as the dye.
  • a second embodiment of the invention provides a recording medium useful for the same or similar purposes, and including an appropriately light absorptive dye having one or more explosive groups chemically associated therewith.
  • the group may be ionically or covalently bonded to the dye molecule, in a manner which does not significantly adversely affect its light absorptive properties.
  • the explosive group is an azide (N 3 -) group or azido group (-N 3 ) respectively.
  • Dye compounds having explosive groups ionically bonded to the dye molecule skeleton i.e. ionic dyes with azide (N 3 -) counterions
  • ionic dyes with azide (N 3 -) counterions can be prepared from known, available ionic dyes by replacement of the counterion thereof (commonly but not exclusively halogen, per ⁇ hlorate, perfluoroborate and the like) by ion exchange with azide, e.g. by use of sodium or potassium azide.
  • the azide ions retain their thermal instability character in such molecules, and the decomposition thereof is readily triggered by the heat generated when the dye portion of the molecule is irradiated, to effect the desired change in optical characteristics of the recording medium in the locality of the incident radiation.
  • dye-explosive counterion compound shows significant advantages over the use of separate dye compounds and explosive compounds, in that the intimate association of the dye portion and explosive portion in the same molecule leads to a more efficient and rapid energy transfer to trigger the explosive decomposition.
  • dye-explosive counterion compounds can be deposited onto the substrate in a single layer, from solution, and without the necessity of the use of a binder material. Consequently, potential problems of the interference of the binder substance in the energy transfer from the dye to the explosive group are avoided.
  • Rhodamine 6G having normally a chloride counterion.
  • the chloride counterion is replaced with azide counterion, thus:
  • the same process can be adopted to convert a wide range of other ionic dyes to their azide counterion form, for use in this embodiment of the present invention. Further, the process is not limited to azide counterions. Other explosive ions such as fulminates, picrates and azide/diazonium ions can also be employed in ionic dye-explosives of this aspect of the invention.
  • This embodiment of the invention may also provide a recording medium useful for the same or similar purposes, and including an appropriately light absorptive dye having one or more explosive groups covalently bonded to the dye molecule.
  • the explosive group e.g. azido group
  • Such a transfer of energy from the dye to the explosive group is particularly efficient in such a system, since the absorptive dye portion and the explosive portion are bonded together in the same molecule, through covalent bonds.
  • Such materials can be applied to the substrate by simple coating from solution. No binder is required to maintain them in place on the substrate so that there is no loss of energy to the binder material in the operation of the optical recording process.
  • Dyes containing explosive groups of this covalent type can be prepared.
  • An example is an amino-substituted benzothiazole compound, which can be reacted firstly with glutaconic dialdehyde anil, then with nitrous acid and then with sodium azide, to effect substitution of covalently bonded azido group onto the molecule in place of amine, thus*:
  • the invention may also provide a recording medium useful for the same or similar purposes, and including an appropriately light sensitive dye-transition metal azide explosive complex in which the dye is the ligand in the transition metal azide-complex explosive.
  • Such complexes were referred to above.
  • a great many of the dyes with absorption characteristics rendering them useful in the present invention also contain amine groups which provide free electron pairs.
  • Cupric azide for example, will, therefore, bond to such a dye (utilizing a dative covalent linkage) substantially in the same manner as the cupric azide will form complex explosives materials with amine compounds disclosed previously.
  • dye complexes may be formed, e.g. of general formula
  • R and R are H, CH 3 , etc.
  • Such a complex retains the absorptive characteristics of the dye and the explosive decomposition property of the azide groups, and permits ready transfer of energy from the dye portion to trigger explosive decomposition of the azide.
  • any nonporous material with a smooth surface can be used as a substrate to support the photosensitive material.
  • Glass plates of 0.060", 0.090" and 0.250" thickness have been used as have polymethylmethacrylate (PMMA), polyester, polyacetate sheets and polycarbonate sheets or films.
  • Substantially transparent materials would be required if it is desired to record by directing the incident beam through the substrate, as in the embodiment of Fig. 2.
  • polished metal plates or any reflective or clear plastic could be used as a substrate.
  • Glass or a polymeric material, such as those listed above, can be plated with a material, such as gold or aluminum, to provide a substrate with a reflective surface on which to adhere the photosensitive layer.
  • a metal azide layer can be formed directly on any smooth surface, in many instances it is advantageous to provide a subbing layer between the photosensitive layer and the substrate.
  • the subbing layer can improve the bonding of' the photosensitive layer to some substrates and may have one or more additional uses.
  • a subbing layer may serve to reduce the surface tension of the solution, resulting in a thin homogeneous coating.
  • a subbing layer can also provide a smooth and receptive surface on which to apply the photosensitive material.
  • a subbing layer which functions as an insulating layer, between the reflective layer and the active layer, and, in some cases, between the active layer and the protective layer.
  • this is a polymeric layer.
  • Polymethylmethacrylate and polycarbonate layers have been used satisfactorily.
  • Refractory materials such as silicon dioxide and zinc sulphide have also been used satisfactorily.
  • a subbing layer of the proper thickness will serve to maximize the reflection through a recorded spot on such a substrate due to constructive interference of the incoming and reflected beam, thus maximizing the signal to noise ratio (SNR) of the medium.
  • SNR signal to noise ratio
  • Gelatin, PMMA, polycarbonate and PVA are examples of materials suitable for use as subbing layers. Layers of such materials have been solvent coated from water solutions, a toluene solution in the case of PMMA, or a toluene methylene chloride solution in the case of polycarbonate. Any plastic or refractory material may serve as a subbing layer if it has the proper optical, thermal, and solvent characteristics.
  • a cover layer can be provided over the recording layer to protect the recording layer from scratches and to keep dust from the focal plane.
  • Successful cover layers have been made of PMMA, PVA, polycarbonate, silicone rubber, and glass.
  • the PMMA was solvent cast from a toluene solution.
  • the PVA was cast from a water solution.
  • the polycarbonate was solvent cast from a toluene/methylene chloride solution.
  • the silicone rubber (RTV) was polymerized in place from a liquid monomer, and the glass was adhered to the recording layer using an optical adhesive.
  • Cover layers of greater thickness (5/1000 - 47/1000 inch) comprising extruded polycarbonate sheet, cast PMMA sheet and glass have been laminated to the recording layer using optically transparent UV-curable adhesives.
  • the cover layer should be substantially transparent to the incident radiant energy beam. Recording with laser light has been performed through layers of each of the above materials. To protect the cover layer from scratching, an abrasion-resistant UV-curable coating 5-25 microns thick is used.
  • a beam of high-intensity radiant energy such as laser light, is directed toward the medium as shown in Fig. 2 or 3. Radiant energy is absorbed by the photosensitive material, particularly any dye that is present, until there is sufficient energy to activate the exothermic decomposition of the metal azide complex.
  • Cupric azide o-toluidine complex can be formed in bulk, dissolved in aqueous ammonia, mixed with a binder and solvent coated to form a homogeneous layer on a substrate. Subsequent coating with an appropriate dye dissolved in solvent renders the layer sensitive to laser radiation of choice.
  • Polycarbonate of thickness 10/1000 inch is metallized with 1000 Angstroms of aluminum.
  • a spacer layer of polymethylmethacrylate 0.01-0.05 microns thickness is spin coated onto the metal layer from a PMMA/toluene solution.
  • a binder layer 0.1-0.5 micron thick, consisting essentially of 8 ml 2% aqueous polyethylene glycol and 2 ml cupric azide o-toluidine/complex dissolved in ammonium hydroxide is spin coated onto the spacer layer.' The ammonia evaporates during spin coating, leaving a layer of polyethylene glycol containing a dispersion of cupric azide o-toluidine complex.
  • U.V. curable adhesive is spin coated onto the dye layer, and then a transparent substrate (PC) of thickness 10/1000 inch to 47/1000 inch is laminated under pressure to the multilayer and U.V. cured.
  • the laminated material so prepared acted satisfactorily as an optical recording medium, using incident low intensity laser radiation from a semi-conductor laser diode.
  • Rhodamine 6G chloride dye 1 g is dissolved in 20 ml 1:1 mixture of acetone and methanol. 0.2 g sodium azide is dissolved in 2 ml water, and added slowly to the stirred, dry solution and stirred for a further 10 minutes to room temperature. Sodium sulphate is then added to dry the solution. After filtration, the solvent is removed under vacuum leaving green crystals of Rhodamine 6G azide.
  • This compound can be solvent coated onto a suitable substrate, without a binder, to provide an optical recording material according to the invention.
  • a substrate was formed by metallizing a polycarbonate film (4"x3"), having a thickness of 10/1000 inch with 1000 Angstroms of aluminum.
  • a spacer layer of polymethyl methacrylate (PMMA) of a 0.01 - 0.05 micron thickness was spin-coated at 600 RPM onto the metallized polycarbonate from a 1% solution of PMMA in tolulene.
  • Solution 1 and Solution 2 were prepared as outlined below and to 1.3g of Solution 2 was added 0.5g of Solution 1. The mixture was mixed briefly, filtered and spin-coated onto the PMMA layer of the substrate at 600 RPM to form a card.
  • the sensitivity of the coating to writing with an 830 nm laser was increased by 1.9 times over the sensitivity of a card having IR- 125 dye alone.
  • Copper sulfate in the amount of 2.5g (10 -2 mole) in 50 ml water was mixed with 1.4g sodium azide (2.15 x 10 -2 mole) in 100 ml water. The precipitate was filtered and washed with water. The filtered copper azide was dissolved in a methanolic ammonia solution (16% NH 3 ) containing 1.2g ethylene diamine (2.0x10 -2 mole). The total weight of the solution was 44.4g or 3.15% in Cu (N 3 ) 2 . The solution was concentrated to 5.1% by evaporation of the excess volatiles in a stream of nitrogen. To redissolve some precipitated Cu (N 3 ) 2 , methanolic ammonia was added (5.1g). The resulting solution was 4.2% in Cu(N 3 ) 2 .
  • Example 5 Using the same procedure as in Example 5, 1.3g of the solution of IR-125 (Solution 2 in Example 5) was mixed rapidly with 15 drops of the 7% stock solution of Cu(N 3 ) 2 - diethylenetriamine to form a mixture solution. After filtration, a substrate similar to that of Example 5 was spin-coated with the mixture solution at 600 RPM. The sensitivity of the coating to writing with an 830nm laser was increased by 1.75 times.
  • Solutions 1 and 2 were prepared as outlined below. To 5g of Solution 2 was added lg of Solution 1. After fast stirring and immediate filtration, the resultant solution was spin-coated onto a substrate similar to that of Example 5 at 2000 RPM. The sensitivity of the coating to writing with an 830nm laser was increased by 1.4 times.
  • Solution 1 was prepared in the same manner as Solution 1 in Example 7.
  • Solution 2 was prepared as outlined below.
  • IR-125 dissolved in methanol was added 2g of a 10% solution of polyethylene imine 1200 (Virginia Chemicals) in methanol and lg of a 2% solution of nonylphenolethoxylate (NPl) in methanol.
  • polyethylene imine 1200 Vanginia Chemicals
  • NPl nonylphenolethoxylate

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Optical Record Carriers And Manufacture Thereof (AREA)
  • Non-Silver Salt Photosensitive Materials And Non-Silver Salt Photography (AREA)

Abstract

Matériau d'enregistrement (42) utilisant un composé explosif et un colorant. Le colorant est choisi de façon à absorber une radiation lumineuse incidente (40) émise par une source laser et à chauffer, déclenchant une explosion du composé explosif dans le voisinage de la radiation lumineuse incidente, et former dans le matériau d'enregistrement (42) des indices que l'on peut détecter optiquement. Dans une forme d'exécution, l'explosif est un complexe d'azide d'un métal de transition tel qu'un complexe azide cuprique-amine. Dans d'autres formes d'exécution, le colorant est modifié de façon telle qu'un groupe azide instable thermiquement lui soit associé chimiquement, afin de grouper dans une même molécule la capacité d'absorption du colorant et le caractère explosif. Les mises en oeuvre de l'invention permettent d'obtenir une solubilité améliorée du matériau explosif dans le colorant.
PCT/US1987/002904 1986-11-07 1987-11-09 Materiau d'enregistrement comprenant un complexe d'azide metallique et des explosifs colorant-azide Ceased WO1988003667A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US92802786A 1986-11-07 1986-11-07
US928,027 1986-11-07

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WO1988003667A1 true WO1988003667A1 (fr) 1988-05-19

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5278023A (en) * 1992-11-16 1994-01-11 Minnesota Mining And Manufacturing Company Propellant-containing thermal transfer donor elements
US6027849A (en) * 1992-03-23 2000-02-22 Imation Corp. Ablative imageable element

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6027849A (en) * 1992-03-23 2000-02-22 Imation Corp. Ablative imageable element
US5278023A (en) * 1992-11-16 1994-01-11 Minnesota Mining And Manufacturing Company Propellant-containing thermal transfer donor elements

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