JPH0373955A - Method of forming negative working image using photosensitive microcapsule - Google Patents

Abstract

PURPOSE: To obtain a method for forming a negative image from a photosensitive microcapsule by uniformly exposing a base body with ultraviolet ray after thoroughly exposing the base body with high-intensity ultraviolet ray into an image state, and then, photosetting photosettable composition which is not perfectly inverted as the result of an image exposure process. CONSTITUTION: The microcapsule includes a photosetting composition including light initiator. The photosetting composition is inverted, or comparatively desensitized when the composition is still more exposed with high-intensity radiation. First, the substrate is thoroughly exposed with the high-intensity ultraviolet ray in the image state, the photosettable composition in an exposure area is inverted, then, the composition is uniformly exposed with low-intensity ultraviolet ray so as to photoset the photosettable composition which is not perfectly inverted as the result of the image exposure process. Thus, due to the symmetrical behavior of the composition shown in the figure, the image is formed from the microcapsule which is partially, or perfectly inverted. Thus, the negative image is formed from the photosensitive microcapsule.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to negative working imaging methods using photosensitive microcapsules. More specifically, the present invention utilizes two steps of reversal development and exposure to actinic radiation to produce negative images from photosensitive microcapsules.

2. Description of the Prior Art A photosensitive imaging system using microencapsulated radiation-sensitive compositions has been developed by Trillion de Corporation (M.
U.S. Pat. No. 4,399,209 and U.S. Pat.
, 416,966 and U.S. Co-pending Application No. 320.643, filed January 18, 1982. These imaging systems are characterized by imagewise exposure of an imaging sheet having a microcapsule layer containing a photosensitive composition in the internal phase to actinic radiation. In the most typical embodiment, the photosensitive composition is a photopolymerizable composition comprising a polyethylenically unsaturated compound and a photoinitiator, encapsulated with a color forming precursor. Imagewise exposure hardens the internal phase of the microcapsules. Following exposure, the imaged sheet is subjected to a uniform breaking force by passing the sheet through a nip between a pair of pressure rollers.

U.S. Pat. No. 4,399,209 discloses a transfer system that combines an imaging sheet with a developer sheet before applying a destructive force to the imaging sheet. When passed through a pressure roller in contact with a developer sheet, the microcapsules rupture and imagewise release the internal phase, where the color former transfers to the developer sheet and reacts with the dried developer to form a colored form an image. The imaging system can be designed to reproduce monochrome or multicolor full-color images.

U.S. Pat. No. 4,440,846 discloses a so-called "self-contained" imaging system in which imaging agent and developer materials are placed on the same substrate. U.S. Patent No. 4.440.846
In the system according to the present invention, an imaging agent is encapsulated in a pressure rupturable capsule layer, and subsequent exposure and rupture of the capsule causes the imaging agent to contact and react with a developer to form an image on the substrate.

The image forming materials and image forming methods described in the above references are positive working in nature (ie, the produced image is an exact copy of the original image). It would be desirable to design an imaging system that uses photosensitive microcapsules that are negative working. In such a system, the image produced would be a perfect inversion of the original image, e.g.
It may be preferred to produce high quality negative images of originals such as microfilm and microfiche which are negative working originals.

Several methods have been proposed for generating negative images.

One method described in said publication is to include photosoftenable or photodepolymerizable materials in microcapsules. Although the system does produce negative images, it has been difficult to implement industrially.

Reversal imaging methods are well known in silver halide photographic systems. The method can take several forms, including bleach/re-exposure methods and transfer diffusion methods. The method does not use photopolymerizable microcapsules.

Another method of producing negative images is to utilize photopolymerizable compositions containing nitroaromatic compounds that can be converted to photoinhibitors. The resulting photoinhibitor acts to prevent photopolymerization of ethylenically unsaturated compounds capable of addition polymerization by free radical initiated chain growth reactions. The inhibitor is produced by exposing the composition to actinic radiation of a specified wavelength for a specified period of time. Such a system is disclosed in US Pat. No. 4,269,933.

In the case of photocurable or photopolymerizable systems, the portions of the photosensitive layer corresponding to the bright colored or opaque areas of the original are photocured, while the portions of the photosensitive layer corresponding to the light colored or transparent areas of the original are photocured. A negative image can be produced in which portions of the image are not substantially photocured.

Negative images are obtained by using the inversion method.

The process is not disclosed for use with photosensitive microcapsules.

For photosensitive compositions, the sensitometric behavior is illustrated by the H&D curve. FIG. 1 is a typical H&D curve showing the behavior of a positive working system. As can be seen from FIG. 1, the density of the image decreases with increasing exposure. For comparison, the H&D curve of a photosensitive material showing reversal at the same exposure scale is shown in Figure 2. In this system, the H&D curve has two different parts,
i.e., a first "positive" region where the system is subject to behavior as shown in the figure, and a second "negative" region where the density of the image increases with increasing exposure.
Including area.

In the case of a system such as that shown in FIG. 2, a positive image or a negative image can be produced by manipulating the exposure intensity and exposure time.

If it is desired to produce a negative image, the process steps are controlled to use only the "negative" portion of the H&D curve.

For example, U.S. Pat. No. 3,380,825 discloses a reversal imaging method using a photocurable composition in the photosensitive layer. The method includes a first imagewise exposure under conditions such that a gaseous polymerization inhibitor depletes the actinic radiation-excited photoinitiator in the exposed area before any substantial polymerization occurs. The photosensitive layer is then shielded from the gaseous inhibitor during a second non-imagewise exposure to the same source of actinic radiation. Industrial-scale implementation of the zero-line method, in which polymerization occurred only in areas where the photoinitiator was not depleted by the first imagewise exposure, required the painstaking steps necessary to produce reversal images of excellent quality. Did not succeed due to cumbersome operations.

U.S. Patent Nos. 3,782,951 and 3,888;
No. 672 discloses a photopolymerizable method by which a reversal image can be obtained. This method uses an ethylenically unsaturated monomer, an organic polymeric binder, and an initiator system as
Includes the use of photopolymerizable compositions that include lophine dimers as well as hydrogen donor compounds.

The composition is subjected to a first intense imagewise exposure followed by a second non-imagewise less intense exposure. By using this method a negative image is generated.

The image is produced as a result of the first exposure step employing a so-called inversion phenomenon that deactivates the photopolymerizable composition in the imagewise exposed portions. The success of this method depends on five variables. These variables are the concentration of hydrogen donor compound, the concentration of lophine dimer, the concentration of ethylenically unsaturated monomer, and the concentration of organic polymeric binder, and the exposure intensity. Therefore, the production of a good negative image requires manipulation of the five variables mentioned above.

Therefore, a technical need exists to generate negative images by utilizing the inversion phenomenon in conjunction with photopolymerizable microcapsules.

Furthermore, when producing a copy image by utilizing a positive working system using photosensitive microcapsules, the background portion of the image-forming sheet is selectively exposed to light in order to avoid unnecessary image formation on the developer sheet. Negative working systems may be preferable to positive working systems since the imagewise exposure step that is required to produce the image appears to be necessary only in the areas where the image is to be produced; such a system is technically The system is particularly useful for producing photocopies from physical objects containing only original manuscripts. Direct recording systems utilizing photosensitive microcapsules and inversion phenomena have not been developed.

Accordingly, there is a need in the art for a direct recording copying system that utilizes photosensitive microcapsules.

The term "reversal time" refers to constant exposure (E) (where:
E = Intensity (■) x Time (T)), refers to the exposure time during which the photosensitive substance cannot yet reach Dsin;
For constant exposure (IXT), for exposure times longer than the reversal time, the photosensitive material follows reciprocity and shows no reversal.According to the invention, the increase in intensity for exposure times shorter than the reversal time is Provides a proportional increase in image density. reciprocity
ty) means that when the exposure increases, the image density decreases as a result of increased polymerization.

According to the present invention, a negative working image forming method using photosensitive microcapsules is provided. The final method preferably utilizes the inversion phenomenon.

According to the invention, a substrate containing photocurable microcapsules is exposed to actinic radiation twice. The first exposure is a short imagewise exposure step with high intensity. The high-intensity, short-duration exposure step is followed by a second overall exposure that serves to reverse or desensitize the photopolymerizable properties of the microcapsules in the exposed areas so that the internal phase of the microcapsules cannot be cured. Microcapsules that were not completely inverted as a result of the exposure process harden. Furthermore, due to the sensitometric behavior of the composition as shown in FIG.
It is possible to generate images from partially or fully inverted microcapsules.

According to one aspect of the present invention, the process comprises a first coating having a microcapsule layer coated on at least one surface of the substrate.
the microcapsules comprising a substrate of a color former and a free radical addition polymerizable or crosslinkable compound and absorbing actinic radiation to initiate free radical polymerization or crosslinking of the polymerizable or crosslinkable compound. All photocurable products contain photoinitiators capable of generating free radicals. The photocurable composition is further characterized in that it reverses or proportionally desensitizes upon exposure to high intensity radiation. The substrate is first imagewise exposed to actinic radiation of sufficiently high intensity to cause reversal of the photocurable composition in the exposed areas and then uniformly exposed to actinic radiation of low intensity to produce an imagewise exposure. The photocurable composition that was not completely inverted as a result of the process is cured. The microcapsules then apply a uniform destructive force to create an image.

In another aspect, the invention relates to a method of producing full color images. The method includes forming a first photocurable composition comprising a first imaging agent and a first sensitivity associated with the first imaging agent on at least one of the front or back side of the substrate. a second group of microcapsules comprising a second imaging agent and a photocurable composition having a second sensitivity associated with the second imaging agent; and a third imaging agent; a third group of microcapsules comprising a photocurable &11 precept having a third sensitivity associated with the third imaging agent;
second and third photocurable compositions comprising a substrate having a coating that flips when exposed to high intensity radiation, the three microcapsules being exposed to three bands of sufficiently high intensity actinic radiation; selectively imagewise exposing the group to cause reversal of the photocurable composition in exposed areas, the three bands of actinic radiation corresponding to the first, second, and third sensitivities; uniformly exposing the substrate to actinic radiation to cure the photocurable composition within each of the three groups of microcapsules that did not completely invert as a result of the imagewise exposure step; and applying a uniform destructive force to the microcapsules in the presence of a developer material to generate an image.

It is therefore an object of the present invention to provide a method for producing negative images from photosensitive microcapsules.

Another object of the invention is to generate negative images from photosensitive microcapsules by exploiting the phenomenon of inversion.

Another object of the present invention is to produce a negative image by subjecting a substrate containing photosensitive microcapsules to two exposure steps: a short, high intensity imagewise exposure step, and a global uniform exposure step. .

Yet another object of the present invention is to utilize commercially available light sources, such as lasers, to briefly imagewise expose the photosensitive microcapsule layer.

Another object of the present invention is to generate resulting positive images from "negative image" originals such as photographic negatives, microfilm and microfiche.

Another object of the invention is to produce negative images from photosensitive microcapsules in a transfer imaging system.

Another object of the invention is to produce negative images from photosensitive microcapsules in a self-contained imaging system.

Yet another object of the present invention is to provide a method for making photocopies using a direct recording system.

These and other objectives will be readily appreciated and understood by those skilled in the art upon reference to the following detailed description of the preferred embodiments.

The sound of ゛ is suitable! ! While describing birch, specific terminology is used for clarity. It is to be understood that such terminology includes not only the recited embodiments, but also all technical equivalents that perform substantially the same function in substantially the same way to achieve the same result.

To begin the method according to the invention, the imaging sheet must be provided with an imaging sheet coated on one surface with a layer of microcapsules. The microcapsules contain a radiation curable composition and a photocurable composition that includes a photoinitiator. Photocurable compositions, such as photopolymerizable and photocrosslinkable materials, thicken or solidify upon exposure to radiation. An imaging agent is associated with the microcapsules.

Various radiation-sensitive materials, photoinitiators, and imaging agents can be used with the photographic materials of the present invention to produce negative images by the reversal process.

Ethylenically unsaturated organic compounds are useful radiation curable materials. These compounds contain at least 1 per molecule
ethylene end groups.

Typically these compounds are liquids. Polyethylenically unsaturated compounds having two or more ethylene end groups per molecule are preferred. An example of this preferred subgroup is trimethylolpropane triacrylate-1- (TMPT
A) and dipentaerythritol hydroxypentaacrylate) (1) Ethylenically unsaturated acid esters of polyhydric alcohols such as PIP^).

The inversion phenomenon is not completely understood and is thought to involve a combination of interactions, as described in more detail below. Furthermore, the reversal phenomenon differs significantly between photosensitive compositions. Some compositions invert in a very short time, and some of them have a time too short to be useful for this technique, while other compositions have long inversion times. The strength of the internal phase exhibiting the zero inversion phenomenon that can be shown and used in the present technology is mainly the type of monomer used in the internal phase, and the type and concentration of the photoinitiator used in the internal phase.

At present it is necessary to create photocurable compositions with relatively long reversal times and in particular to determine the initiator from the group of known free radical initiators by trial and error.

Photoinitiator systems suitable for use in the present invention include ionic dye-counterion compounds described in European Application Publication No. 0233587. A preferred class of ionic dye counterions are cationic dye borates and more particularly cyanine dye borates. Typically the borate is a triphenyl alkyl borate, such as triphenylbutyl borate.

Other dye complexes such as rose bengal iodonium as well as rose bengal biryllium complexes can also be used.

Examples of other photoinitiators with potential utility in the present invention include diarylketone derivatives, quinones, benzoin alkyl ethers, alkoxyphenyl ketones, 0-acylated oxyiminoketones, polycyclic % enones, and benzophenone substituted products, xanthones,
One can choose among thioxanthones, chlorosulfonyl and chloromethyl polynuclear aromatics, chlorosulfonyl and chloromethyl heterocyclics, chlorosulfonyl and chloromethylbenzophenones and halogenated compounds such as fluorenones and haloalkanes. In many cases, it is advantageous to use the photoinitiators in combination with imaging photoinitiators.

The initiator containing the ionic dye complex may preferably contain an autooxidizing agent. Suitable examples include N,N-dialkylanilines as described in the European application.

A variety of imaging agents can be used with radiation curable compositions. For example, images can be formed by the interaction of color formers and color developers of the type commonly used in the carbonless paper industry. moreover,
Images can be formed by color-forming interactions between chelating agents and metal salts, or by the reaction of oxidation-reduction pairs, many of these methods being investigated for use in pressure-sensitive carbonless papers. . Alternatively, oil-soluble dyes can be used and images can be formed by transfer to plain or treated paper. The internal phase itself has unique imaging capabilities. For example, it is known that many of the toners used in electrophotographic recording methods adhere selectively to imaged portions of imaging sheets that are exposed and developed as in the present invention.

Furthermore, the imaging agent can be provided on the microcapsule wall inside the microcapsule, or on the same layer as the microcapsule or in a different layer outside the microcapsule. In the latter case, the internal phase captures the imaging agent (eg, by dissolution) upon release from the microcapsules and transports it to the developer layer or accompanying developer sheet.

Typical color precursors useful in the above embodiments include colorless electron donating compounds. Typical examples of such color formers include lactones, lactams, sulfones,
There are substantially colorless compounds having an ester or amide structure, such as spiropyran, triarylmethane compounds, bisphenylmethane compounds, xanthine compounds, fluorans, thiazine compounds, spiropyran compounds, and the like.

Crystal Violet Lactone and Copikem X, IV and X I (H4l
ton-Davis Chemical Co.) are often used alone or in combination with the power generation precursors of the present invention, such as commercially available cyan, magenta, and yellow color formers.

The discrete-walled microcapsules used in the present invention can be produced using known encapsulation techniques, including conservation, interfacial polymerization, polymerization of one or more monomers in oil, and the like.

Representative examples of suitable wall-forming agents include gum arabic, polyvinyl alcohol, and carboxymethyl cellulose.
2,800,457); resorcinol formaldehyde wall-forming agents (see Hart et al., U.S. Pat. No. 3,755,190); isocyanate wall-forming agents (Vassiliades, U.S. Pat. No. 3,914,5);
(see No. 11); isocyanate-polyol wall-forming agent (
U.S. Pat. No. 4,001,140 to U.S. Pat. , No. 4,087,376,
and melamine formaldehyde resins and hydroxypropyl cellulose (Shackle, commonly assigned U.S. Pat. No. 4,089,802);
025,455). Particularly preferred are melamine formaldehyde capsules.

The average size of the microcapsules used in the present invention typically ranges from about 1 to 25 microns.

The most common substrates for imaging sheets according to the present invention are transparent films or paper sheets, which can be industrial pressure sensitive base papers, or cast-coated paper sheets, which can be special grade papers such as Colom paper. . The latter two papers are preferred when using microcapsules having a diameter of about 1 to 5 microns, since their surfaces are smooth and therefore do not easily embed the microcapsules into the fibers of the base paper. . Transparent and translucent substrates such as polyethylene terephthalate can also be used in the present invention. Another preferred substrate for microcapsules is aluminized mylar (PUT). Microcapsules can be placed on either the front side, the back side, or both the front and back sides of the transparent substrate to create an imaging sheet.

To initiate the reversal effect, the substrate is briefly imagewise exposed to high intensity radiation. Exposure conditions will vary depending on the nature of the photocurable composition. If the exposure intensity is not high enough, the composition can polymerize instead of inverting. The exposure can include wavelengths in the ultraviolet, visible, and infrared spectral regions. Therefore, the radiation source and exposure time must be selected to reverse the photosensitivity & 11th precept. Typical exposure intensity is 200
0ergs/cta” exceeds 101,000er/c
m" to 32,000 ergs/cm". Furthermore, exposure times range from a few microseconds to a few seconds. In a preferred embodiment, a commercially available laser or other high intensity light source emitting light in the ultraviolet or visible spectrum is used as the light source for the first exposure step.

As a result of the first imagewise exposure, inversion or desensitization occurs in the portions of the substrate exposed to radiation. More specifically, microcapsules that receive sufficient imagewise exposure do not harden and become uncurable.

In the present invention, a number of theories have been proposed regarding the zero inversion phenomenon, where inversion can only occur if the photocurable composition contains a photoinitiator and a polymerizable monomer.

Although not wishing to be bound by any particular theory, imagewise exposure by short high intensity radiation exposure results in the photoinitiator being depleted in the microcapsules before the monomers have a chance to polymerize. It is assumed that stopping occurs at a faster rate than the propagation of the part. Another theory posits that polymerization inhibitors or radical scavengers are created within the microcapsules.

Furthermore, it has been discovered that by optimizing the concentration and amount of monomer and initiator, radiation source and exposure time, the photosensitive composition can be somewhat or completely reversed. Looking at the H&D curve of Photosensitivity & 11 Precepts, which is reversed, the image density decreases with exposure until the reversal region of the curve is reached (i.e., until the reversal region is reached, the image density is inversely proportional to the exposure), on the H&D curve. In the inversion region, as seen in , the image density is directly proportional to the amount of exposure received (i.e., the density increases with increasing exposure), and since exposure is a direct product of intensity and time, there is no inversion (
i.e., complete polymerization) to reversal (i.e., complete termination)
The radiation source or exposure time can be selected to produce any image density in the reversal region over . In areas where there is some reversal of the photosensitive material, it is assumed that some reversal results from some, but not complete, depletion of the initiator.

The substrate is then uniformly exposed to actinic radiation to cure any photocurable &[l acid that was not completely inverted. Any light source capable of polymerizing non-imagewise exposed microcapsules can be used.

The exposure can include wavelengths in the ultraviolet, visible, and infrared spectral regions. In a preferred embodiment, a tungsten halogen white light source may be utilized.

The length of the uniform exposure step is selected to complete photopolymerization of the portions that are not completely inverted.

After a uniform exposure step, a uniform destructive force is applied to the microcapsules on the substrate in the presence of a developer material to destroy the microcapsules and form a reversal image, if the image forming agent is not a dye or a pigment. The developer material is selected to react with the imaging agent to form an image. Examples of color developers useful in connection with embodiments using the color precursors are clay materials such as acid clay, activated clay, attapulgite, etc.; organic acids such as tannic acid, gallic acid, methyl gallate, etc. ; Acidic polymers such as phenol formaldehyde resin, phenolacetylene condensation resin, condensate of formaldehyde and organic carboxylic acid having at least one hydroxyl group; zinc salicylate, tin salicylate, zinc 2-hydroxynaphthenate, 3.5-diter metal salts of aromatic carboxylic acids such as zinc t-butylsalicylate;
For example, US Patent No. 3,672,935;
732.120 and 3,737,410)
, zinc carbonate, etc., and mixtures thereof. A suitable type of gloss capable developer is described in commonly assigned U.S. Application No. 073,036, filed July 14, 1987.

A developer material can be placed on a support separate from the imaging sheet, thereby forming a transfer image coating system. In such systems, an imaging sheet and a developer sheet are brought into contact in the presence of a uniform destructive force to transfer the imaging agent to the developer sheet and form an image on the developer sheet.

The support can be made of a transparent film such as polyethylene terephthalate or polyethylene terephthalate.

Alternatively, the developer material can be placed on the same side as the microcapsule layer to form a self-contained sheet. In this construction, the substrate is coated with a first developer material followed by a second coat of developer material.
coated with a photosensitive microcapsule coating. Alternatively, the microcapsules and developer material can be mixed and coated as a single layer as readily understood in the art.

By carrying out the above method, a negative image is produced on the substrate. The photosensitive microcapsules of the imaging sheet that correspond to the white or transparent areas of the original image have released their contents, while the microcapsules that correspond to the dark areas of the original image have not released their contents, as a result of which the image is generate.

The inventors have further discovered that the inversion phenomenon can be influenced by the following parameters, and thus by controlling the parameters the process conditions can be modified. For example, by changing process parameters, the time span over which the imagewise exposure step is carried out can be changed.

The inventor has discovered that by increasing the temperature of the photosensitive material,
It has been discovered that the inversion time can be increased by lengthening the zero time width to make the inversion more easily occur.

In method a, which uses a heating step before the imagewise exposure step, the substrate must be cooled to approximately ambient conditions before the uniform exposure step. Cooling of the substrate can be accomplished by any means known in the art, such as fans.

The inventors have further discovered that monomer composition can affect reversal time. Although not wishing to be bound by any particular theory, the inventors hypothesize that the internal layer viscosity of the microcapsules may be related to the inversion time. The inventors have discovered that when using monomers with low viscosity, the inversion time tends to be longer (and thus the composition is more likely to be inverted) than when using monomers with high viscosity. For example, if you use TMPTA as the raw monomer and want to increase the inversion time of the system to facilitate the inversion process, you would add a polymerizable monomer of lower viscosity than TMPTA to the system. Alternatively, if short inversion times were desired, high viscosity monomers would be added to the internal phase. Preferably, the photocurable compositions used in the present invention exhibit reversal times ranging from a few nanoseconds to a few seconds.

Since the invention can be advantageously used to provide a negative working system, it can be used to produce direct recording copies. This is particularly advantageous when copying original documents that contain a limited amount of visible material on the sheet, such as typed text. In a preferred embodiment, the imagewise exposure is carried out using a laser as the source of actinic radiation. Since the laser path can be carefully controlled by methods well known in the art (eg, computer control), this provides an extremely useful method.

This is especially true if the image to be reproduced contains predominantly white or transparent areas. According to the method of the invention,
The corresponding area of the substrate is subjected to a simple general exposure step to harden the microcapsules.

The invention can be used to produce monochrome or full color images. The full-color image system is based on U.S. Patent No. 4,576.891 and European Patent Application No. 022.
No. 3587 and British Patent No. 2.113,860. These systems use an imaging site with three groups of microcapsules containing cyan, magenta, and yellow color precursors, respectively. As explained in more detail in the references cited above, each group of microcapsules is primarily sensitive to a different wavelength band that allows the microcapsules to be exposed individually with minimal crosstalk. In the panchromatic system, cyan,
Magenta and yellow forming photosensitive microcapsules are sensitive to red, green and blue light respectively.

According to the invention, each of the three groups of microcapsules contains a reversible photocurable composition. moreover,
The composition selected for each microcapsule group is sensitive to different wavelength bands.

To generate a full-color image, each group of microcapsules is imagewise exposed to high-intensity radiation.
An inversion is caused in each image exposure portion. This requires exposure to three different wavelengths, each wavelength corresponding to the sensitivity of the photocurable composition selected for the corresponding set of microcapsules. The three different wavelengths can be provided by one broad band radiation source or three independent monochromatic radiation sources. In a panchromatic system, it is envisioned that green, blue and red lasers are used in the short exposure step. These methods rely on image processing techniques well known in the art. Furthermore, it is expected that high intensity white light sources containing at least three bands of actinic radiation can be used for short-term exposures.

After a short exposure, the substrate is subjected to a uniform exposure step to harden any microcapsules that were not completely inverted. The substrate is then contacted with a developer material to rupture the microcapsules in the presence of the developer material and produce an image.

The invention is further illustrated by the following non-limiting examples.

EXAMPLE 1 The composition below was encapsulated in melamine formaldehyde microcapsules and coated onto 3 mil polyethylene terephthalate film.

Trimethylenepropane triacrylate 100 parts Cyanine borate photoinitiator 2 parts Diisopropyldimethylamine 6 parts Cyan color former
Part 6 Death Module N-10
The coated substrate was heated to 50°C. The substrate was then placed at a distance of about 19 cm from 3
A 60 watt tungsten halogen light source was imagewise exposed for 4 seconds through a 30 step light density wedge to permanently lack reciprocity in the high intensity regions (
i.e., capsules were produced that terminated faster than they polymerized. The optical density wedge was removed and the substrate was rapidly quenched to ambient conditions using a cooling air gun. The substrate was uniformly exposed to a fluorescent/black light source for an additional 12 seconds. This low intensity exposure polymerized the capsules that did not invert on the first exposure.

A uniform destructive force was applied to the substrate in the presence of the developer sheet.

The generated image was a negative image of the original image.

Although the invention has been described in detail and with reference to preferred embodiments, it will be obvious that modifications and changes can be made without departing from the scope of the appended claims.

The embodiments of the present invention are as follows.

1. A method for producing an image-forming sheet capable of producing a reversal image including the following steps: A substrate having one surface coated with a microcapsule layer is prepared, and the microcapsules contain (i) an image-forming agent and (ii) a photocurable composition comprising a free radical addition polymerizable or crosslinkable compound and a photoinitiator, the photoinitiator absorbing actinic radiation to bond the polymerizable or crosslinkable compound; the photocurable composition is capable of generating free radicals that initiate free radical polymerization or crosslinking of the compound, and the photocurable composition is one that reverses upon exposure to high intensity radiation; imagewise exposing the substrate to actinic radiation of high intensity to cause inversion of the photocurable m-acid in the exposed portion; and uniformly exposing the substrate to actinic radiation to perform the imagewise exposure step. Curing the photocurable composition that did not result in complete inversion.

2. The method of 1 above, wherein the photoinitiator comprises an ionic dye-reactive counterion compound.

3o The method of the above second method, wherein the ionic dye-reactive counterion compound is a cationic dye-porate anion compound.

4. The substrate can be photocured by heating it to a temperature higher than ambient temperature! 2. The method of claim 1, comprising an additional step of increasing the conversion time of the compound acid.

5. The method of claim 1, wherein said imagewise exposing step comprises exposing said substrate to light emitted from a laser.

6. The method according to 5 above, wherein the photocurable composition is sensitive to visible light.

7. The imagewise exposure step exposes the substrate to approximately 2000 erg.
2. The method of claim 1, comprising exposing to actinic radiation having an intensity greater than 1.

8. An image generation method comprising the following steps: A first substrate coated with a microcapsule layer on at least one surface is provided, and the microcapsules contain (i) an image forming agent and (ii) a free radical addition polymerizable material. or a photocurable composition comprising a crosslinkable compound and a photoinitiator, the photoinitiator absorbing actinic radiation to initiate free radical polymerization or crosslinking of the polymerizable or crosslinkable compound. the photocurable composition is capable of generating free radicals, and wherein the photocurable composition reverses upon exposure to high intensity radiation; causing a reversal of the photocurable composition in portions; uniformly exposing the substrate to actinic radiation such that the photocurable composition did not completely revert as a result of the imagewise exposure step; providing a second substrate coated with a developer material on one surface, the developer material reacting with the imaging agent to form an image on the second substrate; applying a uniform destructive force to the microcapsules in the presence of the developer material to imagewise transfer the image forming agent to the second substrate, thereby producing an image thereon;

9. 9. The method of claim 8, wherein the photoinitiator comprises an ionic dye-reactive counterion compound.

10. The method according to 9 above, wherein the ionic dye-reactive counterion compound is a cyanine dye-boric acid ester anion compound.

11. The high intensity radiation is at least about 2000 erg
8. The method according to 8 above, wherein the method is ``s/cra''.

12. The method according to 8 above, wherein the photocurable composition is sensitive to visible light.

13. A method for producing a full color image comprising the following steps: A photocurable composition having a first imaging agent and a first sensitivity associated with the first imaging agent on at least one of the front or back sides. a first microcapsule containing a substance; a second microcapsule containing a substance;
a second microcapsule comprising an imaging agent and a photocurable composition having a sensitivity associated with the second imaging agent; and a third imaging agent and a photocurable composition associated with the third imaging agent. a third photocurable composition having a third sensitivity;
the first, second,
and a third photocurable composition that reverses upon exposure to high intensity radiation.

The three types of microcapsules are selectively and imagewise exposed to three bands of actinic radiation of sufficiently high intensity to cause reversal of the photocurable composition in the exposed areas, and the three bands of actinic radiation three bands corresponding to said first, second, and third sensitivities, wherein said substrate is uniformly exposed to actinic radiation, and said three bands are not completely reversed as a result of said imagewise exposure step; and applying a uniform destructive force to the microcapsules in the presence of a developer material to produce an image.

14. The method according to 13 above, wherein the three image forming agents include a cyan color former, a yellow color former, and a magenta color former.

15. The imagewise exposure step exposes the microcapsules to 3
16. The method according to 15 above, comprising exposing the method to radiation emitted from two lasers.

16. The method according to 15 above, wherein the three lasers include a first laser that emits red light, a second laser that emits green light, and a third laser that emits blue-violet light.

17. The method of claim 14, wherein the three bands of actinic radiation are provided by a high intensity white light source.

[Brief explanation of drawings]

Figure 1 shows positive working photosensitivity &1I7i! This is the H&D curve of the object. FIG. 2 is an H&D curve of a photosensitive composition showing positive image and negative image forming properties. FIG, 1 FIG, 2 (4 others) to>E

Claims (1)

[Claims] 1. A method for producing an image-forming sheet capable of producing a reversal image, which includes the following steps: A substrate whose one surface is coated with a microcapsule layer is prepared, and the microcapsules ( a photocurable composition comprising: i) an imaging agent; and (ii) a free radical addition polymerizable or crosslinkable compound and a photoinitiator, the photoinitiator absorbing actinic radiation to the photocurable composition is capable of generating free radicals that initiate free radical polymerization or crosslinking of the polymerizable or crosslinkable compound, and the photocurable composition reverses when exposed to high intensity radiation. , imagewise exposing said substrate to actinic radiation of sufficiently high intensity to cause reversal of said photocurable composition in exposed areas, and uniformly exposing said substrate to actinic radiation to cause said Curing the photocurable composition that has not completely reversed as a result of the imagewise exposure step. 2. The method of claim 1, comprising the additional step of heating the substrate above ambient temperature to increase the reversal time of the photocurable composition. 3. An image generation method including the following steps: A first substrate coated with a microcapsule layer on at least one surface is provided, and the microcapsules contain (i) an image forming agent and (ii) a free radical addition polymerizable material. or a photocurable composition comprising a crosslinkable compound and a photoinitiator, the photoinitiator absorbing actinic radiation to initiate free radical polymerization or crosslinking of the polymerizable or crosslinkable compound. the photocurable composition is capable of generating free radicals, and wherein the photocurable composition reverses upon exposure to high intensity radiation; causing a reversal of said photocurable composition in a portion; uniformly exposing said substrate to actinic radiation to remove said photocurable composition that has not completely reversed as a result of said imagewise exposure step; curing the article; providing a second substrate coated with a developer material on one surface, the developer material reacting with the imaging agent to form an image on the second substrate; applying a uniform destructive force to the microcapsules in the presence of the developer material to imagewise transfer the imaging agent to the second substrate to form an image thereon; 4. A method of producing a full color image comprising: a photocurable composition having on at least one of the front side or the back side a first imaging agent and a first sensitivity associated with the first imaging agent; a first microcapsule containing a substance; a second microcapsule containing a substance;
a second microcapsule comprising an imaging agent and a photocurable composition having a sensitivity associated with the second imaging agent; and a third imaging agent and a photocurable composition associated with the third imaging agent. a third photocurable composition having a third sensitivity;
the first, second,
and a third photocurable composition that reverses upon exposure to high intensity radiation. The three types of microcapsules are selectively and imagewise exposed to three bands of actinic radiation of sufficiently high intensity to cause reversal of the photocurable composition in the exposed areas, and the three bands of actinic radiation three bands corresponding to said first, second, and third sensitivities, wherein said substrate is uniformly exposed to actinic radiation, and said three bands are not completely reversed as a result of said imagewise exposure step; and applying a uniform destructive force to the microcapsules in the presence of a developer material to produce an image.