KR20050097510A - System for labeling a substrate and method of labeling an optical disk - Google Patents

Abstract

Systems (10) and methods of labeling optical disk (14) recording media and other substrates using leuco dyes in an electromagnetic radiation sensitive composition are described. Leuco dyes containing isobenzofuranone are prepared in various compositions that include activators and radiation absorbers, and optionally non-leuco colorants, and/or a variety of carriers. The leuco dye compositions can be applied and prepared to achieve a desired visual effect upon development of the leuco dye.

Description

SYSTEM FOR LABELING A SUBSTRATE AND METHOD OF LABELING AN OPTICAL DISK}

The present invention relates generally to the use of leuco dyes. More specifically, the present invention relates to the use of black leuco dyes for labeling substrates.

Optical discs represent most of the market for storage of photographic, video and / or audio data as well as software data. Typically, optical discs contain data patterns thereon, such that they can be read from graphic displays printed on one or both sides of the disc and the other side of the disc. The data-readable side or data side of the disc is variably spaced depressions (which are referred to as pit) separated by an undepressed surface (which is referred to as a land). Spiral track). The low power laser is focused on the spiral track. The height difference between the pit and the land creates a phase shift in the reflection beam that can be measured and interpreted as available data. Various optical disc formats such as CD, CD-ROM, CD-R, CD-RW, DVD, DVD-R and DVD-RW are currently available. Other optical disc formats are also available.

To verify the contents of the optical disc, the printed pattern or graphic display information can be printed on the non-data side of the disc. The pattern or graphic display can all be decorated and can provide permanent information about the data content of the disc. Conventionally, commercial labeling has been achieved using screen-printing methods. This method can provide a wide range of label content, but due to the fixed costs associated with manufacturing stencils or combinations thereof and printing the desired pattern or graphic display, it is difficult to produce less than about 400 discs. Tends to be cost effective.

In recent years, the use of optical discs for data storage has been greatly increased in accordance with the demand for providing labels ordered by the consumer to reflect the contents of the optical discs. Labeling methods acceptable to most consumers are limited to pre-printed labels and handwritten descriptions, which can be attached to the disk but also negatively impact disk performance as they spin at high speeds.

Summary of the Invention

It is recognized that it would be advantageous to develop alternative systems and methods for labeling substrates such as optical disks.

In one embodiment, an optical disc according to an embodiment of the present invention may comprise an optical disc substrate coated thereon with an electromagnetic radiation sensitive composition. The electromagnetic radiation sensitive composition comprises a leuco dye capable of forming a black image upon development, wherein the leuco dye is an isobenzofuranone-containing dye. The electromagnetic radiation sensitive composition may also include an activator formed to react with the leuco dye. In addition, the electromagnetic radiation sensitive composition may include an electromagnetic radiation absorber mixed with or in thermal contact with a thermally active leuco dye under the influence of electromagnetic radiation sufficient to promote a reaction.

The invention also includes a system for labeling a substrate comprising an image data source, a substrate coated thereon with an electromagnetic radiation sensitive composition, and a radiation source for deploying the electromagnetic radiation sensitive composition. The electromagnetic radiation sensitive composition may comprise a leuco dye capable of forming a black image, such as an isobenzofuranone-containing dye, depending on the development. The composition may also include an activator formed to react with the leuco dye, and an electromagnetic radiation absorber mixed with or thermally contacted with the thermally active leuco dye under the influence of electromagnetic radiation sufficient to catalyze the reaction. The electromagnetic radiation source can be operatively connected with the image data source and can be formed to direct electromagnetic radiation for the electromagnetic radiation sensitive composition.

In another embodiment, a method for labeling an optical disc can include a series of steps. The first step comprises applying an electromagnetic radiation sensitive composition comprising the black leuco dye, an activator and an electromagnetic radiation absorber, which is an isobenzofuranone-containing dye, to the surface of the optical disc. The second step includes transferring the image data from the data source to an electromagnetic radiation source configured to produce electromagnetic radiation. The third step may include inducing color changes in at least a portion of the electromagnetic radiation sensitive composition to produce a visible image on the optical disc by exposure to electromagnetic radiation at a predetermined frequency, density, time and spot size. Can be.

Further features and advantages of the invention will become apparent from the following detailed description of the features of the invention in conjunction with the accompanying drawings.

1 is a schematic diagram of a system for labeling a substrate in accordance with an embodiment of the present invention.

2A, 2B and 2C are cross-sectional views of a portion of an optical disc in accordance with some exemplary embodiments of the present invention.

Reference is made to the exemplary embodiments described in the drawings, in which specific terms are used herein to describe it. Nevertheless, it will be understood that it is not intended to limit the scope of the invention. Modifications and further modifications to the features of the inventions described herein, and those further applicable to the principles of the invention as described herein, which are possible to those skilled in the art and included herein, are deemed to be within the scope of the invention. Should be. In addition, before disclosing and describing particular embodiments of the invention, it should be understood that the invention is not limited to the specific methods and materials disclosed herein as may be modified to some extent. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting, as the scope of the invention is limited only by the appended claims and their equivalents.

In describing and claiming the present invention, the following terms will be used.

The singular forms “a”, “an” and “the” include plural objects unless the context clearly dictates otherwise. Thus, for example, reference to "a" leuco dye includes the reference to one or more of these materials.

As used herein, “optical disc” is meant to include audio, video, multimedia and / or software discs, which are machines readable by CD and / or DVD drivers and the like. Examples of optical disc formats include writable, recordable and rewritable discs such as DVD, DVD-R, DVD-RW, DVD + R, DVD + RW, CD, CD-ROM, CD-R, CD-RW, and the like. This includes. Other similar formats may also be included, such as future formats and similar formats.

As used herein, a "graphical display" can include any visible feature or image found on an optical disc. Typically, graphical displays are found primarily on one side of an optical disc, although not always.

As used herein, "data" is typically used to include non-graphical information contained on an optical disc that is digitally or otherwise included therein in view of the present disclosure.

As used herein, “isobenzofuranone-containing” refers to any compound comprising a subgroup of the following formula as suitable for use in the present invention.

As used herein, a "leuco dye" is a dye that is in a substantially colorless or white form prior to development and blackens upon exposure to heat. Color-change phenomena appear due to chemical change from thermal exposure, for example through oxidation.

The term "activator" refers to a composition that interacts or reacts with a leuco dye upon thermal introduction.

As used herein, “developing” or “developing” refers to the interaction or reaction of a leuco dye with another agent, such as an activator, to produce a visible composition having the desired color. The interaction is mostly thermally initiated but can also be physical in nature.

As used herein, "absorbent" generally refers to an electromagnetic radiation sensitive agent capable of generating heat upon exposure to electromagnetic radiation of a predetermined frequency. The predetermined frequency may vary from one absorbent composition to the next. When mixed or in thermal contact with the leuco dye and / or activator, the absorbent may be present in an amount sufficient to generate sufficient heat to at least partially develop the leuco dye in accordance with embodiments of the present invention. Typically, the development of the leuco dye can be derived from the interaction between the leuco dye and the activator composition.

The term "thermal contact" refers to the spatial relationship between an absorbent and a leuco dye-activator composition. For example, if the absorbent is heated by interaction with electromagnetic radiation, the heat generated by the absorbent should be sufficient to blacken the leuco dye through reaction with the activator. Thermal contact may include a very close proximity between the absorbent and the leuco dye, which enables heat transfer from the absorbent towards the leuco dye and / or activation. In addition, thermal contact can include, for example, the actual contact between the absorbent and the leuco dye in a mixture comprising very adjacent layers or both components.

A "carrier" or "carrier component" is defined to include additives and compositions that can be used with leuco dyes, absorbents and / or activators to form one or more layers on the surface of a substrate. Surfactants, polymers, UV curable materials and the like can be used as the carrier. The combination of the leuco dye and the absorbent may be within a conventional carrier or may be present as a separate carrier applied successively to the substrate. Additives such as colorants may be added to the carrier in some embodiments.

As used herein, “optical density” refers to the logarithm of the inverse of the reflectance, which is the ratio of reflected power to incident power.

Concentrations, amounts, and other numerical data can be provided herein in a range format. This range format is used only for convenience and brevity, and includes not only the numerical values explicitly quoted as a limitation of the range, but also the individual numerical values contained within the same range as each numerical value and subrange are explicitly quoted. It should be interpreted flexibly to include both values or subranges. For example, the size range of about 1 to about 200 μm may be explicitly stated concentration limits of 1 to about 200 μm, as well as individual concentrations such as 2 μm, 3 μm, 4 μm, and 10 to 50 μm, 20 To be interpreted to include subranges such as from 100 μm or the like.

As shown in FIG. 1, a system for labeling a substrate having a black leuco dye thereon, generally indicated at 10, according to the present invention is presented. In this embodiment, the system can simultaneously write to the image plane 12 of the optical disc 14 and collect and / or write data to the data plane 16 of the optical disc. The optical disc substrate 18 is shown in a first orientation, with the image plane 12 facing upward. The motor 20 and the support member 22 are provided to spin and support the optical disk 14.

According to the invention, the image is digitally stored on an image data source 24. This image information can be generated using any number of commercially available image software programs. The image is then rasterized or spiralized and delivered to the labeling electromagnetic radiation source via signal processor 26. This process generally involves digitizing the image data to correspond to the spiral passage that matches the passage and then digitizing the electromagnetic radiation source to the image plane of the optical disc during spin. In one embodiment, the labeling electromagnetic radiation source is an emission device 28a and an optional label detection device 30a facing the image plane 12 of the spin optical disc 14 having the leuco dye composition 32 thereon. . In addition, the optional second emitting device 28b and the second detecting device 30b face the data plane 16 and are arranged for simultaneous operation of reading and / or writing. Data may be generated, used and / or stored at the data source 34. In one embodiment, data can be written by sending it to the second emitting device 28b via the signal processor 26. Each emitter and detector set is located on a first sled 36a and a second sled 36b, respectively. Further, the first sled 36a and the second sled 36b respectively follow the first track 38a and the second track 38b. In this embodiment, a single solenoid 40 appears to act to move both the first sled 36a and the second sled 36b simultaneously and to collect information in unison. However, this is not essential.

In other embodiments, each sled may take a form independent of the other. In such embodiments, the use of two solenoids or other mechanical or electrical structures can be implemented for independent function. In addition, other embodiments are possible, such as the use of a single track and solenoid combination as is acceptable in conventional CD-R / CD-W drives. The same emitter and diode combination is used to read and write data, after which the disk is inverted and the black image is developed using the leuco dye of the present invention.

The present invention generally relates to labeling substrates using certain black leuco dyes. As shown in Figures 2A, 2B and 2C, the optical disc, generally represented as 14, comprises a substrate 18 having several coatings. Substrate 18 is generally used for structural supports and has a data face 16 and a label face 12. The substrate 18 may be made of any suitable material, such as polycarbonate for optical discs, or other polymeric material. The data layer 42 is generally formed by sputtering or other known processes and may contain any known material that can create, maintain, and / or simulate pits and lands corresponding to specific data. Thus, although a single data layer is presented, it is understood that multiple layers may be used, for example, for a writable and / or rewritable format. As such a material (ROM) for permanent use, a writable or rewritable format is well known to those skilled in the art. These materials include, but are not limited to, aluminum, cyanine, phthalocyanine, metallized azo dyes and photosensitive compounds in the polymer binder in the dye layer. For example, rewritable optical discs typically include quaternary phase-change alloys that exhibit various reflective properties in amorphous and crystalline states. The data layer may also contain colorants that do not affect the data storage performance of the data layer. The composition is readable or writable with respect to the data face 16 of the optical disc 14.

The black leuco dyes and activators of the present invention can be applied to optical discs made in a number of ways and that are data readable or writable. For example, as shown in FIG. 2A, an electromagnetic radiation sensitive composition 44 containing a black leuco dye, an activator, an electromagnetic radiation absorber and a carrier can be prepared. The carrier may be a surfactant and / or polymeric material such as Almacryl® T-500, polyacrylates, polyvinylalcohols, cellulose esters, polyvinyl pyrrolidines, polyethylene, polyphenols or polyphenolic from monomers and oligomers Esters, polyurethanes, and the like. The electromagnetic radiation sensitive compositions of the presented embodiments not only provide leuco dye and activator functions, but also are used to protect the upper surface of the disc, thereby imparting several additional components such as lubricants, surfactants, and moisture resistance. Materials) can also be added to provide mechanical protection against electromagnetic radiation sensitive compositions.

In other embodiments, the electromagnetic radiation absorber may be applied in separate layers relative to the leuco dye layer, wherein the individual layers are located on the substrate before and after the leuco dye. 2B shows a leuco dye layer 46 containing a black leuco dye and an activator in a suitable carrier. This composition is formed in the data layer 42 and may cover only the entire surface or only a portion of the optical disc 14. In the embodiment shown in FIG. 2B, the absorbent layer 48 may be formed (using absorbent in the carrier) as a separate layer, which covers at least a portion of the optical disc. Thus, the leuco dye layer 46 and the absorbing layer 48 combine to make up the electromagnetic radiation sensitive composition. In one embodiment, for the leuco dye composition 46 that develops as desired on the optical disk surface, the absorber layer 48 is formed at least in close proximity to the same site of the optical disk 14 as the leuco dye layer 46. Can be. This provides an optical disc having an absorbent layer 48 in thermal contact with the leuco dye layer 46. If the two layers are not actually in contact but close enough to cause thermal activation of the leuco dye, the layers may be considered to be in thermal contact. The optional passive protective layer 50 can be formed to add mechanical protection to the leuco dye layer 46 and the absorbent layer 48. The protective layer can be substantially transparent or translucent to allow sufficient electromagnetic radiation to pass through, thereby allowing the electromagnetic radiation sensitive composition to develop.

In another embodiment of the invention, FIG. 2C shows an optical disc 14 having a substrate 18, a data layer 42 and a first protective layer 52. The electromagnetic radiation sensitive composition layer 42 comprises a leuco dye, an activator, an electromagnetic radiation absorber and carrier (s) having an absorbent and a leuco dye with the activator in a separate layer or mixed together as described above. It can be prepared to. The first protective coating layer 52 protects the data layer 42 as is conventional for commercially available writable and rewritable optical discs. The second protective coating layer 56 protects the electromagnetic radiation sensitive composition layer (s) 54. Such protective coatings can be coatings including lacquers, UV coats or polymer films.

In each of the embodiments and equivalent embodiments listed in the figures, the black leuco dye suitable for use in the present invention is an isobenzofuranone-containing dye. Generally, leuco dyes are substantially colorless and exist in the form of lactone-closed rings. Such dyes include leuco fluorane dyes such as 3-di-n-pentylamino-6-methyl-7-anilinofluorane, 3-di-n-butylamino-6-methyl-7-anilinofluorane, 3 -(n-ethyl-n-isopentylamino) -6-methyl-7-anilinofluorane and 3-pyrrolidino-6-methyl-7-anilinofluorane. Corresponding chemical structures are as follows.

Leuco dyes containing halides such as isobenzofuranone leuco dyes may also be used in the present invention. The halide-containing isobenzofuranone leuco dye is tetra-halide composition 1 (3H) -isobenzofuranone, 4,5,6,7-tetrachloro-3,3-bis [2- [4-dimethylamino) Phenyl] -2- (4-methoxyphenyl) ethenyl], which has the following structure.

Depending on heat-induced oxidation, protonation, ring-opening, etc. in the presence of an activator, the isobenzofuranone-containing leuco dyes cited above can form black dyes with high optical density. Although a wide range of compositions are suitable for use in the present invention, the electromagnetic radiation sensitive composition may contain less than about 60% by weight of leuco dyes and activators, preferably about 40% by weight. These ranges are exemplary only and other weight ranges may be used differently depending on the desired image properties and other considerations. An activator to leuco dye weight ratio of about 1: 4 to 4: 1 typically provides sufficient results, and a ratio of about 2: 1 can also be used.

As stated, the interaction between the leuco dye and the activator causes a chemical change in the leuco dye, which changes the color of the leuco dye from substantially white or colorless to substantially black. In general, chemical changes in leuco dyes occur with the application of a certain amount of heat. Suitable activators for the present invention can be selected by those skilled in the art. Some non-limiting examples of suitable activators include phenol, carboxylic acid, Lewis acid, oxalate complex, succinate acid, zinc stearate, and combinations thereof.

As an amount of heat is provided by the electromagnetic radiation absorber, matching of the electromagnetic radiation frequency and intensity to the absorber used can be achieved to optimize the system. While other weight ranges may be required depending on the activity of the particular absorbent, the absorbent may typically be present in the electromagnetic radiation sensitive composition in an amount of about 0.001 to about 10 weight percent. Examples of frequencies that can be selected include infrared light, visible light, ultraviolet light, or a combination thereof.

The absorbent may be formed to be in a thermally conductive relationship with the isobenzofuranone-containing leuco dye. For example, the absorbent may be located in the same layer as the isobenzofuranone-containing leuco dye as part of the mixture, or may be present in separate layers. Thus, the absorbent may be mixed with or in thermal contact with the leuco dye composition. In one embodiment of the invention, the absorbent may be applied to the substrate in individual adjacent layers before and after applying the leuco dye composition as a layer. In one embodiment, the choice of activator can also be considered such that any light absorbed within the visible range does not negatively affect the graphical display or appearance of the undeployed leuco dye. Although inorganic compounds may be used, the absorbent may be an organic compound, typically including but not limited to infrared absorbers, ultraviolet absorbers and visible light absorbers. More particularly, examples of absorbents suitable for use in the present invention include, but are not limited to, metal complex IR dyes, indocyanine green, heterocyclic compounds, and combinations thereof. Metal complex IR dyes such as dithiolein metal complexes having the following formulas may be used.

Where

M is a transition metal,

R1 to R4 may be lower alkyl or aryl groups.

Indoaniline metal complexes such as the compounds of the following formulas may also be suitable.

Where

M is Ni, Cu or other transition metal,

Each R may independently be H, lower alkyl and / or aryl.

Some commercial IR absorber compounds, such as IR780 and IR783 (Aldrich Chemical Company) and dithiophenylidene compounds (Syntec 9/1 and Syntec 9/3), respectively, presented below are also described herein. Can be used for

Other suitable absorbents may be used in the present invention and are well known to those skilled in the art and are described, for example, in "Infrared Absorbing Dyes", Matsuoka, Masaru, ed., Plenum Press (1990) ( ISBN 0-306-43478-4), and ["Near-Infrared Dyes for High Technology Applications", Daehne, Resch-Genger, Wolfbeis, Kluwer Academic Publishers (ISBN 0-7923-5101-0)]. . Certain activators and absorbers discussed herein are individual compounds, and such activity may also be provided by a constituent group of leuco dyes that incorporate activation and / or radiation absorbing action within the leuco dye molecule.

According to another aspect of the invention, the black isobenzofuranone leuco dye may be developed under conditions exposed to certain types of electromagnetic radiation, including electromagnetic radiation generated using a laser. Lasers that generate radiation within the visible, infrared and ultraviolet frequencies are available. For example, lasers having a frequency of about 650 to about 815 nm are readily commercially available.

The conditions under which the leuco dyes of the present invention can be varied can be varied. For example, one of them can change the electromagnetic radiation frequency, heat flux and exposure time. Variables such as spot size and laser power also affect any particular system design and can be selected based on the desired result. In these variables, the electromagnetic radiation source may apply electromagnetic radiation to the electromagnetic radiation sensitive composition in accordance with image data sources and information received from the signal processor. In addition, the leuco dye and / or activation concentration and proximity to each other may also vary.

Although the leuco dye of the present invention can be developed using a laser using 15 to 100 mW power, lasers with power outside this range can also be used. The spot size may be determined in consideration of the electromagnetic radiation source and may be about 1 to about 200 μm, although smaller or larger sizes may also be used. In one embodiment, radiation spot sizes of about 10 to about 60 μm may also be used. In a further aspect, a spot size of 20 × 50 μm can provide a good balance between resolution and deployment speed.

The thermal flux may vary, and in one embodiment is a variable that may be about 0.05 to 1 J / cm 2 and in a second embodiment about 0.05 to 0.4 J / cm 2. Thermal fluxes within these ranges result in less than about 1000 microseconds / dot in some embodiments, less than about 500 microseconds / dot in other embodiments, and less than 100 microseconds / dot in another embodiment. Allow.

To illustrate an example where these variables may be provided together in a single embodiment, a leuco dye composition and activator by using a spot size of 20 × 50 μm, a 35 mW laser and 100 microseconds (exposure) / dot for about 20 minutes Standard CD image surfaces containing can be developed. Optical densities of about 1.4 or more can also typically be achieved. One skilled in the art can adjust these parameters to achieve various resolutions and deployment times.

Other changes can also be implemented, including adding non-leuco colorants to impart additional desired colors to the image. For example, the use of opacifier pigments or other non-leuco colorants can be used to provide a background color to the optical disc. The non-leuco colorant may be an electromagnetic radiation sensitive composition layer (which may include an activator layer and a leuco dye layer, or a mixture of two layers in a single layer, so long as the development of the leuco dye does not migrate negatively), or May be added to the protective layer (s). A portion of the black leuco dye may then be developed to produce a black image with a colored background. Examples of milking agents include calcium carbonate, titanium dioxide and other known milking agents. In addition, examples of other non-leuco colorants include dyes or other pigments. That is, if a colored background is required that remains independent of the leuco dye development, then the bleach pigment, other pigments and / or dyes may be mixed in the carrier to impart the desired color.

In preparing black-forming leuco dyes, such dyes may be prepared in solutions that are transparent or translucent. Any suitable carrier (eg, surfactant) that is miscible with the particular black leuco dye selected can be used. If the black leuco dye is made in solution form, it may be desired to underprint the colored coating over at least a portion of the substrate under the leuco dye solution. The selective colored coating produces a background color that can be seen below the solution layer. This colored coating may contain various non-leuco colorants such as other pigments and / or dyes. Alternatively, non-leuco colorants can be added to the data layer to produce the desired background color. With dispersion, the activator can be mixed into the solution or coated onto the substrate before and after the solution is coated thereon. If the background color is preprinted, such coatings and compositions can be applied to the substrate using any of a variety of known techniques, such as screen-print, spin coating, sputtering or spray coating. After each coating is applied, it can be dried continuously.

Example 1

The solution was dissolved by dissolving about 5 g of polished 4-benzyloxy benzoate containing 0.05% IR783 activator powder in 15.3 g of a UV curable mixture of acrylate monomer and oligomer (available under the trade name Nor-Cote CDG000 UV-lacquer). Formed. Next, 2'-anilino-3'-methyl-6 '-(dibutylamino) fluorane (Nagase Co., Ltd.) having the following formula and having an average particle size of less than about 5 μm. BK-400 leuco dye available from)) was added to the solution.

As activator, 1.9 g of pure bisphenol-A having an average particle size of less than about 5 μm was added to the solution. The solution was made into a fine paste and screen printed to a thickness of about 7 μm on the substrate to form an imaging medium. The coating on the medium was then UV cured with a mercury lamp.

The resulting leuco dye-containing layer was developed with a 45 mW laser at 780 nm. An exposure time of about 20-100 μs produced marks of about 20 μm × 45 μm. The unfolded image was created without intermediate prints and showed high optical density.

Example 2

About 2 g of dibenzyl oxalate powder was heated and melted to about 85 ° C., which was sufficient to melt the powder. To the molten powder was added 20 g of a phenol, 4,4'-sulfonylbis [2- (2-propenyl) activator (available under the trade name TG-SA) of the formula and 1.2 g of IR absorber IR780.

The resulting composition was cooled and ground to fine powder. Next, 1.8 g of the ground fine powder was dissolved in 15.3 g of Nor-Cote CDG000 UV-lacquer as a carrier to form a solution. 15 g of a black leuco dye ((2-anilino-3-methyl-6 '-(N-ethyl-N-isoamylamino) fluorine) of the following formula available from Nagase Co., Ltd. under the trade name S-205. Was added to the solution.

The black leuco dye had an average particle size of less than about 5 μm. In addition, 2.0 g of pure bisphenol-A having an average particle size of less than about 5 μm was added to the solution to form a mixture. The mixture was made into a fine paste and screen printed to a thickness of about 7 μm on the substrate to form an imaging medium. The coating on the medium was then cured using ultraviolet radiation from a mercury lamp.

The leuco dye was then developed using a 45 mW laser at 780 nm on the resulting coated substrate. An exposure time of about 60-100 μs produced marks of about 20 μm × 45 μm. A flattened image was produced without intermediate prints, and a high optical density image was produced.

Example 3

Indocyannine green (1.5 g of 10% solution) in deionized water was thoroughly mixed with 50 g of screen-print paste available from Savoir Fair, Novato, Calif. Under the trade name LASCAUX to form a paste mixture. . Approximately half of the paste was combined with 17 g of the ground black leuco dye (S205 as in Example 2). The leuco dye was ground to an average particle size of less than 5 μm in water slurry as before and dried to about 50% solids. The paste mixture and leuco dye were mixed thoroughly on a roller mill. The remaining portion of the paste mixture was then combined with 33 g of benzyl 4-hydroxybenzoate and mixed thoroughly. Benzyl 4-hydroxybenzoate was prepared by grinding the particles to an average particle size of less than 11 μm and drying to about 50% solids. The resulting combined mixture was then roll-milled to homogenize the components and reduce the average particle size. The resulting mixture was measured with an average fineness of less than 2 μm. The viscosity of the mixture was also measured at 50,000-160,000 cps at 1 rpm, where the curve slope for 10 rpm / 1 rpm was greater than 5.0. The mixture was screen coated on one side of the CD and dried in vacuo at 45 ° C.

The leuco dye was then developed on CD by using a 45 mw laser at 780 nm for a 280 microsecond exposure time. The image printed on the CD showed a high optical density black mark of about 25 μm × 50 μm and had a green background.

It is to be understood that the above-referenced arrangements illustrate the application of the principles of the present invention. Many modifications and alternative arrangements may be devised without departing from the spirit and scope of the invention, but the invention is shown in the drawings. And described above in connection with exemplary embodiment (s) of the invention. It will be apparent to those skilled in the art that various changes may be made without departing from the principles and concepts of the invention as disclosed in the claims.

Claims (15)

An optical disc comprising an optical disc substrate coated thereon with an electromagnetic radiation sensitive composition, the optical disc comprising: (A) a leuco dye, which is an isobenzofuranone-containing dye, wherein the electromagnetic radiation sensitive composition is capable of forming a black image upon development; (b) an activator formed to react with the leuco dye; And (c) a thermally active electromagnetic radiation absorber mixed with or in thermal contact with the leuco dye, which is thermally active under the influence of electromagnetic radiation sufficient to catalyze the reaction. The method of claim 1, Optical disc, in which the absorbent is mixed with leuco dye and thermally active under the influence of electromagnetic radiation. The method of claim 1, An electromagnetic radiation absorber is included in the first layer, and a leuco dye and an activator are included in the second layer, wherein the second layer is in thermal contact with the leuco dye as the absorber is activated by electromagnetic radiation relative to the first layer. Optical disks configured to be. The method of claim 1, Optical disc in which electromagnetic radiation is present in the form of a laser. The method of claim 1, The optical disc, wherein the electromagnetic radiation sensitive composition further comprises a non-leuco colorant. a) image data source; b) a leuco dye, which is an isobenzofuranone-containing dye, capable of forming a black image upon development of i); ii) an activator formed to react with the leuco dye; And iii) a substrate coated with an electromagnetic radiation sensitive composition comprising a thermally active electromagnetic radiation absorber mixed with or in thermal contact with the leuco dye, the thermally active electromagnetic radiation absorber under the influence of electromagnetic radiation sufficient to promote the reaction; And c) an electromagnetic radiation source operatively connected to said image data source and configured to apply electromagnetic radiation to said electromagnetic radiation sensitive composition. The method of claim 6, Wherein the electromagnetic radiation source is in the form of a laser source capable of producing a thermal flux of 0.05 to 1.0 J / cm 2. The method of claim 6, Black images have an optical density of at least 1.3. The method of claim 6, Wherein the substrate has a colored layer underprinted under the electromagnetic radiation sensitive composition. The method of claim 6, The system is an optical disc. As a method of labeling an optical disc, a) applying an electromagnetic radiation sensitive composition comprising an isobenzofuranone-containing dye, a black leuco dye, an activator and an electromagnetic radiation absorber to the surface of the optical disk; b) transferring image data from the data source to an electromagnetic radiation source configured to produce electromagnetic radiation; And c) inducing a color change in at least a portion of the electromagnetic radiation sensitive composition to produce a visible image on the optical disc by exposure to electromagnetic radiation at a predetermined frequency, intensity, time and spot size. The method of claim 11, A method of labeling an optical disc, wherein the electromagnetic radiation sensitive composition is formed of adjacent layers comprising a leuco dye-containing layer and an absorbent-containing layer. The method of claim 11, Delivering the image data comprises digitizing the data to correspond to a spiral passage that matches a passage along an electromagnetic radiation source with respect to the top surface of the optical disk when spinning. The method of claim 11, The method of labeling an optical disc, wherein the electromagnetic radiation sensitive composition further comprises a non-leuco colorant. The optical disc, system or method according to any one of claims 1 to 14, wherein the leuco dye is selected from the group consisting of the following formulas. And