JPS5854380B2 - Photosensitized small bubble light and heat sensitive recording material - Google Patents

Description

Detailed Description of the Invention The present invention uses azobisnitrile as a photosensitive and heat-sensitive component,
This invention relates to a small foam photosensitive and thermosensitive recording material using anthracene as a photosensitizer.

Conventionally, small foam recording materials have been produced by uniformly dispersing, for example, diazonium salts or azide compounds in thermoplastic polymers.
It is known to coat this onto a support such as a plastic film or black paper.

In this small bubble-like photosensitive material, diazonium salt, etc. used as a photosensitizer in exposed areas decomposes when irradiated with ultraviolet rays, producing nitrogen gas.

At the stage of irradiation with light, this gas dissolves into the thermoplastic polymer layer and appears transparent and is indistinguishable from the unexposed areas, but when the polymer layer is heated, the polymer softens and at the same time decomposes. The produced nitrogen gas coalesces and expands into small bubbles, which have a refractive index different from that of the surrounding medium and scatter incident light.

When the image is subsequently irradiated with ultraviolet rays, the photosensitizer in the unexposed areas is decomposed and fixed, forming a light-scattering, small bubble-like recorded negative image.

However, this type of recording material has the disadvantage that the photosensitizer, such as diazonium salt, is unstable with respect to temperature and humidity and has a short shelf life.Furthermore, these photosensitizers are extremely sensitive to light, so these Recording materials using
It is necessary to always block external light from the time of manufacture to the time of development of the recording material, and very strict care is required in its management.

Furthermore, in order to obtain a recorded image using this type of recording material, a fixing process was always required after development.

For example, to obtain this positive image, first a latent image is formed by exposure, then a mild heat treatment is applied for a certain period of time to drive out the ultrafine particulate gas that forms the latent image from the material, and then the material is exposed again. Then, it was necessary to form a latent image at a position opposite to the previous latent image (that is, in the previously unexposed area), and finally, a heat development and fixing process had to be performed again to bubble the positive latent image.

Its operation is extremely complicated and lacks practicality.

The inventors of the present invention have repeatedly searched for various photosensitizers with the aim of solving the various drawbacks of the above-mentioned small bubble-like photosensitive recording materials. It has been found that it can be used as an agent, and a separate patent application has been filed for it (Japanese Patent Application No. 36295/1982).

The present invention uses azobisnitrile represented by the general formula [wherein R and R' represent the same or different linear or cyclic alkyl groups] or the formula as a small-foamed light- and heat-sensitive recording material. be.

Recording materials using azobisnitrile can be stored for long periods of time as azobisnitrile has excellent stability not only against temperature and humidity but also against light. Easy to handle.

For example, at temperatures below 70°C, almost no decomposition of azobisnitrile, which is used as a photo-thermosensitive agent, is observed, and even if it is heated to about 90°C for a short time, its photosensitivity hardly decreases.

Regarding light, there is almost no decrease in photosensitivity even if the product is left indoors for several days with only a fluorescent lamp as the light source, and even when irradiated with direct sunlight for about 30 minutes,
Note that there is no adverse effect on the desired photosensitivity.

Moreover, unlike conventional recording materials, there is no need to perform fixing treatment after exposure and development, and there is an advantage that not only negative images but also positive images can be easily formed by simply adjusting exposure conditions and heat development conditions as appropriate.

Therefore, the recording material of the invention can be advantageously used as a general copying material such as copy paper, and a photographic material for projection for use in appropriate devices such as overhead projectors and microreaders, and has particularly high light stability and shrinkage. When light with an intensity inversely proportional to the reduction area ratio is irradiated, as in the case of small-scale photography, it is possible to obtain clear recorded images with high resolution even if the exposure conditions are weakened. It is suitable as a photographic material.

However, the small foam photosensitive and thermosensitive recording material of the present invention
Since photosensitivity and thermal stability (i.e. storage stability of unexposed raw recording material) conflict with each other, it is suitable for reduced-scale photography such as microfilm, where low photosensitivity is not a practical problem. For example, when using a recording medium for duplication that is printed in close contact with the original film of the subject, that is, a tubular film, it takes a relatively long time to take a picture, so by further increasing the light sensitivity, the time to form a recorded image can be shortened. is desired.

Therefore, the present invention was achieved through repeated research in order to appropriately increase only the photosensitivity of azobisnitrile used as a photosensitive and heat-sensitive component without impairing its thermal stability.

That is, the present invention contains azobisnitrile represented by the general formula (wherein R and R' represent the same or different linear or cyclic alkyl groups) as a photosensitive component and a heat-sensitive component,
This is a photosensitized small-bubble light- and heat-sensitive recording material using anthracene as a photosensitizer.

The azobisnitrile used in the present invention is that of the earlier invention, that is, represented by the above general formula CI) or formula [■], in which R and R' are specifically the same or Compounds that are different are methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, and cyclopropyl groups.

Representative compounds thereof include azobisisobutyronitrile and azobiscyclohexanenitrile.

These azobisnitrile are usually 3300 to 3 soo
The absorption of the azo group becomes remarkable with light having a wavelength around A, and in particular, with light having a wavelength around 3450 nm, the azo group has an absorption peak.

Therefore, it has the property of being decomposed by light including this wavelength to generate nitrogen gas.

Moreover, it has the feature that it similarly decomposes to generate nitrogen gas even when heated to 100° C. or higher.

The recording material of the present invention utilizes the photo-thermal sensitivity peculiar to azobisnitrile.

Among these, those having excellent thermal stability and relatively low photosensitivity, such as azobisisobutyronitrile and azobiscyclohexanenitrile, can be particularly preferably used.

When anthracene is added to these, the storage stability at room temperature is particularly enhanced, and a recording side slope having appropriate photosensitivity can be obtained.

This device not only does not require a special external light shielding device such as a darkroom, but also eliminates the need for a special external light shielding device such as a darkroom, as long as there is no long-term exposure to external light between the time of producing the recording material and the time of development. Exposure time is greatly shortened, which is particularly meaningful from a practical point of view.

It is surprising that a photosensitizer such as anthracene exerts a high degree of effect on substances such as azobisisobutyronitrile and azobiscyclohexanenitrile, which have relatively high decomposition energy and are in solid solution phase. It is the right thing to do.

On the other hand, among the azobisnitriles, those that have excellent photosensitivity but relatively low thermal stability include 2,2'-azobis-2,4-dimethylvaleronitrile, 2,2'-azobis-2-inbutyro, 4-methyl- Recording materials made by adding, for example, anthracene to something like valeronitrile have even more photosensitivity, so they must be stored in a cool, dark place from the time they are manufactured until the time they are developed to block external light. Although it is practically inconvenient, it can be useful for some purposes because it significantly improves photosensitivity.

The amount of anthracene used in the present invention is 3 to 100 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of azobisnitrile as the photosensitive and heat-sensitive component.

If the amount of anthracene added is too small, a sufficient photosensitizing effect will not be achieved, and if it is too large, there will be a tendency for the recording material to bleed.

Further, the usage amount of other compounds having anthracene as a basic structure is also the same as that of the anthracene.

The small foam light and heat sensitive recording material of the present invention, which uses azobisnitrile as a light and heat sensitive agent and anthracene as a sensitizer, is generally used in the form of a thin film using a suitable organic polymer compound as a medium. .

This film is usually prepared by dissolving or dispersing at least one azobisnitrile and the above photosensitizer in a suitable solvent solution of the above-mentioned polymeric medium, and then applying it on a support such as a plastic film or paper according to a conventional method. It can be applied by a coating method, a casting method, etc., or it can be formed by a suitable film forming method such as a calendar method, an extrusion method, etc. according to a conventional method.

Various types of organic polymer compound media can be used as long as they can be formed into a film in a transparent state.

Typical examples include polymethacrylic resins, polyester resins, cellulose acetate resins, appropriate polymeric compounds such as crosslinked products of polymeric polyols and polyisocyanate resins, polyvinyl chloride resins, polyvinylidene chloride resins, polyolefins, and others. Examples include mixtures of the above resins and copolymers of the respective monomers constituting the resins.

In the present invention, about 2 to 70% by weight of azobisnitrile, preferably about 10 to 40% by weight, and anthracene are added to a secondary organic polymer compound, and azo and sumitrile 1 are added as described above.
3 to 100 parts by weight, preferably 5 to 5 parts by weight
By blending with 0 parts by weight, the desired recording material is obtained.

If the amount of azobisnitrile blended is too small, it will be difficult to obtain a clear recorded image with the resulting recording material, and if it is too large, the compatibility with the organic polymer compound will be poor and bleeding will occur easily.

In addition, a wide variety of solvents can be used when producing a film by a casting method, such as ethyl acetate, methylene chloride, methyl ethyl ketone, other esters, alcohols, aromatics, and halogenated hydrocarbons. etc. can be exemplified.

Further, the recording material of the present invention includes the above-mentioned azobisnitrile,
In addition to anthracene and the organic polymer compound medium, various additives such as plasticizers, lubricants, antistatic agents, etc. can be added according to conventional methods.

In addition, for example, when producing a film by a casting method, a wide variety of supports can be used, such as polyethylene terephthalate, polyolefin resins, polyamide resins, etc. Transparent film bases such as resins and cellulose triacetate, and opaque bodies such as paper, glass, plates, and metal plates can be used.

Thus, the light and heat sensitive recording material of the present invention comprises a polymer film formed uniformly containing azobisnitrile as a light and heat sensitive agent and anthracene as a photosensitizer, and a support. can get.

The light and heat sensitive recording material of the present invention can be advantageously used as copying paper, projection film, etc., generally in the form of a light and heat sensitive agent-containing resin film coated on a suitable support as described above. However, if necessary, it is also possible to peel off only the resin film formed on the support to create a single layer film, or to create a three or more layer film with a protective layer provided on the resin film. It is.

Furthermore, the recording material of the present invention can also be formed into a single-layer film by using a calendaring method, an extrusion method, etc. from a composition containing a photosensitive and heat-sensitive agent and its medium. It can be made into two or three layers depending on the support and protective layer described above.

Note that azobisnitrile, which is used as a photosensitive and heat sensitive agent in the present invention, has excellent thermal stability and is not likely to decompose at temperatures below 70°C. There is no need to perform cooling or the like, and it is even possible to slightly heat the film in order to improve its solubility when it is dissolved in a solvent together with a polymer compound and a film is produced by a casting method.

There is no particular restriction on the thickness of the recording material film of the present invention, but if it is too thin, the heat absorption effect during heat development may be reduced, making it difficult to obtain a preferable bubble-like recorded image.

In this case, as described above, it may be used as it is coated on the support, or a protective layer may be provided as the uppermost layer.

To obtain a negative image using the recording material of the present invention, the following operations may be performed.

That is, the recording material of the present invention is exposed together with a subject whose image area is colored (non-transparent) and whose non-image area is made of a material that transmits light.

As the light source, any of various light sources including light with a wavelength around 3450 (3300 to 3800) can be used, such as sunlight, a mercury lamp, a high-pressure mercury lamp, a carbon arc lamp, a xenon lamp, and the like.

Furthermore, for exposure, it is possible to use not only direct projection of light from a light source onto the recording material, but also reflected light or condensed light using a convex lens or the like.

Regarding the exposure time, the azobisnitrile in the portion of the recording material corresponding to the non-image area of the recording material is almost completely decomposed to generate nitrogen gas, but this nitrogen gas is used as a medium in an extremely fine state. It is preferable that the recording material remains completely transparent while remaining dissolved in the resin.

If the exposure time is too short or the exposure intensity is too weak, even if the photosensitizer of the present invention is used, azobisnitrile will not be sufficiently decomposed and nitrogen gas will be generated, making it difficult to form a clear image.

Furthermore, if the exposure is too strong, nitrogen gas generated by decomposition will be dissipated outside the recording material, making it difficult to obtain a clear negative image.

In the present invention, heat development treatment is then performed.

As the heating source used here, any of various conventionally known heat sources such as hot gas, hot liquid, hot roll, hot press, high frequency, etc. can be used.

In order to obtain a clearer image, a far-infrared heater that can instantaneously heat the inside is suitable.

The heat development temperature and time using the heat source may be appropriately determined depending on the type and amount of azobisnide 1,1 and the polymer compound medium used as the recording material, the thickness of the recording material, and the like.

If the heating conditions are too strong, the azobisnitrile present in the unexposed portions of the recording material may form small bubbles due to rapid thermal decomposition.

Nitrogen gas generated during exposure by the heat development is combined and expanded to form countless small bubbles that can be seen with the naked eye, thus obtaining a negative image in which the small bubble portions have light scattering properties.

Further, in order to make the negative image obtained as described above clearer, it is preferable to shorten the time from the start of exposure to the start of development as much as possible.

Although the azobisnitrile in the portion corresponding to the image area of the negative image obtained by the above method remains undecomposed, in the present invention there is no need to fix this portion by re-exposing or the like.

In other words, the azobisnitrile in this part gradually decomposes due to external light, etc., but the extremely fine nitrogen gas that is generated dissipates directly into the atmosphere without expanding or coalescing into bubbles. Therefore, countless small bubbles that can be observed with the naked eye are not formed on the material surface, and there is no risk of light scattering occurring at all.

The recording material of the present invention can also form a positive image with a simple operation similar to the formation of the above-mentioned negative image.

In other words, in order to obtain a Bonn image, the above exposure should be extended for a longer time or the exposure intensity should be increased to first decompose all the azobisnitrile in the area corresponding to the non-image area and remove the generated nitrogen. The gas is dissipated into the atmosphere in the extremely fine state as described above.

The recording material thus obtained, which remains completely transparent to the naked eye, is then heated with a heating device, such as a far-infrared heater, for a longer period of time than is required to obtain a negative image.

By this heating, the azobisnitrile present in the unexposed areas of the recording material is thermally decomposed to generate nitrogen gas, which is foamed by continued heating to form countless small bubbles on the surface of the recording material.

These countless small bubbles are sufficiently visible to the naked eye and are large enough to reflect or refract light, so this portion has light scattering properties and forms a positive image.

This no longer requires any subsequent fixing treatment.

When forming the above positive image, there is no problem if the exposure conditions are strong, but in the unlikely event that some azobisnitrile remains in the exposed area even after exposure, it is preferable to It is best to leave the film for a certain period of time to completely dissipate the remaining nitrogen gas, and then heat and develop it.

In addition, when creating a positive image using the recording material of the present invention, it is of course possible to create a positive image using a method according to the prior art or other well-known methods.

As described above, the recording material of the present invention can be easily formed into negative and positive images by appropriately selecting the intensity of exposure, the time from exposure to development, and the intensity of heating during development. The fact that a positive image can be obtained by such an operation is completely inconceivable from conventional photosensitive materials using diazonium salts and the like.

In addition, by using this recording material, it is particularly useful not only as a microfilm but also as a contact recording medium for duplication (duplicate film), and by appropriately increasing or decreasing the amount of photosensitizer used, Not only does it have the advantage that it can be applied to other appropriate applications and has an extremely wide range of use, but it can also be expected to significantly shorten the image formation time and bring about great benefits.

Although the method of creating negative images and positive images by the transmission method has been described above, the recording material of the present invention is not limited to this, and similarly clear images can be obtained by the reflection method, etc. When applying the reflection method, there is an advantage that ordinary books, literature, etc. can be copied as they are.

Examples are given below to explain the present invention in more detail.

Example 1 5 grams of cellulose triacetate and 41 grams of cellulose diacetate were mixed with 120 grams of methylene chloride. and 36.35 f of a tetrahydrofuran solution in which 1.352 of anthracene was dissolved, and 4 f of azobisisobutyronitrile.
．． 24.5 P of an acetonitrile solution containing No. 51 was added to each, and the mixture was stirred to become uniform.

The thus obtained liquid was applied onto a cellulose triacetate film with a thickness of 100 μm using a tabletop coater, and the film was left to dry for 8 minutes in a thermostatic drying machine at 70° C.

Then, the light and heat sensitive recording material of the present invention was obtained by leaving it in a dark place overnight.

The thickness of this recording body was 120 μm.

On the light-sensitive and heat-sensitive recording material obtained as described above, a document made of a material in which the image area is colored (non-transparent) and the non-image area transmits light is superimposed as a subject, and an IKW high-pressure mercury lamp is used as a light source. Exposure was performed for 30 seconds at a distance of 2.5 CrrL from the light source.

Next, the recording material was left in a dark place overnight to completely dissipate into the air fine nitrogen gas that was invisible to the naked eye and was generated in the portion of the recording material corresponding to the non-image area of the original.

Next, the recording material was heated to a far infrared heater (800W x 1
When heat developed for 6 seconds at a distance of 10 CrIL),
A clear positive image appeared.

Comparative Example 1 A heat-sensitive photosensitive material having a thickness of 120 μm was obtained in the same manner as in Example 1 except that anthracene was not included.

The exposure time was 8 minutes in order to obtain a positive image as clear as in the example.

Example 2 Using the same recording material as used in Example 1, exposure was carried out for 15 seconds in the same manner.

The document was then immediately heated and developed for 4 seconds using a far-infrared heater, and a negative image of the original appeared.

Comparative Example 2 Using the same recording material as used in Comparative Example 1, Example 2
In order to obtain a negative image of the same level of clarity using the same operation as above, an exposure time of 4 minutes was required.

Example 3 Using the same recording material as used in Example 1, the same subject was superimposed and exposed for 30 seconds at a distance of 2.5 CrIL from the light source using a 1K1f high-pressure mercury lamp as a light source.

Next, the recording material was left in a dark place overnight, and then the entire surface was exposed to light for 90 seconds at a distance of 2.5 cn'L from the light source using the same high-pressure mercury lamp as the light source, and then immediately exposed to light using a far-infrared heater (soowxi book). When heat-developed for 6 seconds at a distance of 10 minutes, a clear positive contact image was obtained.

Comparative Example 3 Using the same recording material as used in Comparative Example 1, Example 3
In order to obtain a close-contact image with a positive image of similar clarity, the first exposure time was 8 minutes, and the subsequent full-surface exposure time was 15 minutes.

Claims (1)

[Scope of Claims] 1. Azobisnitrile represented by the general formula [in which R and R propensities or different chain or cyclic alkyl groups are shown] or the formula is used as a photosensitive/heat-sensitive component, and anthracene is A photosensitized small-foamed light- and heat-sensitive recording material, characterized in that it contains a photosensitizer.