JPH0290148A - Image forming method - Google Patents

Abstract

PURPOSE:To obtain high color developing density even by a heat developing at low temperature and yet to maintain a good shelf life by exposing an copying material to light at 60-80 deg.C in a first process and fixing the part except the image forming part by photoirradiation. CONSTITUTION:The copying material is provided on a support with a photosensitive layer containing a diazo compound and a coupling component at least one of both microencapsulated, and capable of being heat developable, and the photosensitive layer is exposed in accordance with an original image to form a latent image on the layer. The part except this image forming part is fixed by the photoirradiation in the first process in the range of 60-80 deg.C, and the latent image is heat developed in the second process, by the color developing reaction of the diazo compound and the coupling component, and the contact between them is prevented by encapsulating at least one of both in a storage state at normal temperature, thus permitting fog to be prevented, and high color developing density to be obtained even at low temperature heat development without deteriorating a good shelf life.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a copying material containing a diazo compound (diazonium salt) encapsulated in microcapsules, which has a particularly good shelf life and high color development J even by low-temperature thermal development.
The present invention relates to a copying material capable of obtaining a high degree of strength and an image forming method therefor.

<Prior Art> There are three types of copying materials that utilize the photosensitivity of diazo compounds.

The first type is known as a wet development type, in which a photosensitive layer containing a diazo compound and a coupling component as main components is provided on a support, this material is superimposed on the original, and after exposure, it is developed in an alkaline solution. It is something to do. The second type is known as a dry development type, which, unlike the wet type, develops with ammonia gas. The third type is known as a heat-developable type, and includes a type that contains an ammonia gas generating agent such as urea that can generate 7-ammonium-7 gas when heated, or a type that contains trichloroacetic acid in the photosensitive layer. There are types that contain alkaline salts of acids that lose their acid properties when heated, and types that utilize higher fatty acid amides as coloring aids to activate diazo compounds and coupling components by heating and melting. .

In addition to maintenance problems such as the need for replenishing and discarding the liquid because the wet type uses a developing solution and the large size of the device, the wet type also has problems with maintenance, such as the fact that it is wet immediately after copying, making it difficult to apply reeds immediately. There are several problems, such as copy images that cannot withstand long-term storage. In addition, like the wet type, the dry type requires replenishment of the developer, requires gas absorption equipment to prevent the generated 7mm27 gas from leaking outside, and therefore requires larger equipment. There are also other problems such as the smell of 7mm smell immediately after copying. On the other hand, unlike wet and dry types, heat-developable types have the advantage of maintenance because they do not require a developer, but all conventional types require high developing temperatures of 150°C to 200°C. Moreover, if the temperature is not controlled to about ±10° C., insufficient development may occur or the color tone may change, resulting in a problem of increased equipment cost. Furthermore, the diazo compound used for such high-temperature development is required to have high heat resistance, but such compounds are often disadvantageous in forming high concentrations. Although many attempts have been made to develop at low temperatures (90° C. to 130° C.), they have the drawback of decreasing the shelf life of the material itself.

As described above, although the thermal development type is expected to have sufficient advantages in terms of maintenance compared to the wet and dry types, the current situation is that it has not yet become the mainstream of diazo copying systems.

Now, in order to obtain the desired color density by heating a material in which a layer containing a diazo compound, a coupling component, and a coloring aid is provided on a support, each component instantly melts, diffuses, and reacts by heating. It is necessary to generate a coloring pigment by If we design a material that can sufficiently develop color and obtain a high concentration even at low heating temperatures, there is always the possibility that this reaction will occur even while it is stored at room temperature before copying, resulting in white color. This appears as a phenomenon in which the bare skin becomes colored.

In order to solve this incompatible problem, the inventors of the present invention made extensive studies and found that a photosensitive layer containing a diazotized metal, a coupling component, and a coloring aid that can be heat-developable is provided on a support. We have discovered that one basic solution to this problem is to incorporate the diazo compound into microcapsules. However, this alone did not produce sufficient effects, and further investigation led to the present invention.

Accordingly, a first object of the present invention is to provide a copying material and an image forming method thereof that can obtain high color density even by low-temperature development.

A second object of the present invention is to provide an image forming method that allows assembly of an apparatus that is easy to maintain and inexpensive.

A third object of the present invention is to provide a copying material that has a good shelf life, that is, a low density of background coloring (fog) during storage before copying.

Means for Solving Problems> The above object of the present invention is to provide a heat-developable photosensitive layer containing a diazo compound and a coupling component, at least one of which is encapsulated in microcapsules, on a support. A first step of exposing the copying material to light corresponding to the image of the original to form a 5-alternate image on the photosensitive layer and fixing the area other than the image forming area by irradiating light, followed by heating and developing. The present invention has been achieved by an image forming method comprising a second step, wherein the first step is exposed at a temperature range of 60°C to 80°C. At this time, the wall of the microcapsule is preferably made of a polymer material formed around the core material by polymerization after emulsifying the core material of the microcapsule, and the polymer material is selected from polyurethane and polyurea. at least 1
Preferably, it is formed by seeds.

Effects> The copying material and image forming method of the present invention make it possible to lower the heat development temperature while maintaining a good shelf life. By containing at least one of the diazo compound and the coupling component involved in the coloring reaction in the microcapsules, they are prevented from coming into contact with each other during storage at room temperature, thereby preventing the occurrence of fog. Furthermore, as a result of the study, the present inventors focused on reducing the heat development temperature.
It was discovered that uniformly heating the entire photosensitive layer before the heat development process to a temperature that does not cause color reaction is extremely effective in lowering the developing temperature or shortening the developing time.

Furthermore, as a result of continuing studies to meet the purpose of the present invention of simple and inexpensive maintenance, the inventor discovered that the above effects could be similarly obtained by controlling and utilizing the heat generation of the exposure section light source. I came up with an invention.

The diazo compound and the coupling component contained in the photosensitive layer of the present invention develop color when they come into contact with each other when heated, and the diazo compound decomposes when exposed to light of a specific wavelength before the coloring reaction. Photodegradable compounds are used.

The photodegradable diazo compound as used in the present invention mainly refers to aromatic diazo compounds, and more specifically refers to aromatic diazonium salts, diazosulfonate compounds, and diazoamino compounds. It is generally said that the photodecomposition wavelength of a diazo compound is its maximum absorption wavelength. Also, the maximum absorption wavelength of diazo compounds ranges from around 200 nm to 70 nm, depending on their chemical structure.
It is known that it changes to about 0 nm. (“Photodecomposition and chemical structure of photosensitive diazonium salts” by Takahiro Tsunoda and Ao Yamaoka, Journal of the Photographic Society of Japan 29 (4) pp. 197-205 (
1965)) That is, when a diazo compound is used as a photodegradable compound, it is decomposed by light of a specific wavelength depending on its chemical structure. Furthermore, by changing the chemical structure of the diazo compound, the hue of the dye after the reaction can be changed even when the same coupling component is used for the coupling reaction.

A diazo compound is a compound represented by the general formula ArN2X. (In the formula, Ar represents a substituted or unsubstituted aromatic ring%
N2 represents a diazonium group, and x represents an acid anion. ) In the present invention, a multicolor heat-developable copying material can be obtained by using diazo compounds having different photodecomposition wavelengths or different photodecomposition rates.

Specific examples of the diazo compound used in the present invention include the following examples.

4-Diazo-1-dimethyl 7-minobenzene, 4-diazo-2-butoxy-5-chloro-1-dimethylaminobenzene, 4-diazo-1-methylbenzylaminobenzene, 4-diazo-1-ethylhydroxyethyl 7-minobenzene , 4-diazo-1-diethylamino-3-methoxybenzene, 4-diazo-1-morpholinobenzene, 4-
Diazo-1-morpholino-2,5-dibutoxybenzene.

4-Diazo-1-tolylmercapto-2,5-jethoxybenzene, 4-diazo-1-piperazino-2-methoxy-5-chlorobenzene, 4-diazo-1-(N,N
-dioctyl7minocarbonyl)benzene, 4-diazo-1-(4-tert-octylphenoxy)benzene, 4-diazo-1-(2-ethylhexanoylpiperidino)-2゜5-dibutoxybenzene, 4 -Diazo-1-
(2゜5-G ter t-7 Milphenoxy α
-butanoylpiperidino)benzene, 4-diazo-1-
(4-methoxy)phenylthio-2,5-jethoxybenzene, 4-diazo-1-(4-methoxy)benzamide-2,5-jethoxybenzene.

4-Diazo-1-pyrrolidino-2-methoxybenzene Specific examples of the acid that forms a diazonium salt with the above diazo compound include the following examples.

c,,F,,C0OH (r+ is an integer from 1 to 9), C1F
2-+, IS Oy H (m is an integer of 1 to 9), boron tetrafluoride, tetraphenylboron, hexafluorophosphoric acid, aromatic carboxylic acid, aromatic sulfonic acid.

Metal halides (zinc chloride, cadmium chloride, tin chloride)
etc.) The coupling components used in the present invention are those that form a dye by coupling with a diazo compound in a basic atmosphere, and include so-called active methylene compounds having a methylene group next to a carbonyl group, phenol derivatives, naphthol derivatives, etc. The following are specific examples:

Resorcin, FOO Glucine, Sodium 2,3-dihydroxynaphthalene-6-sulfonate, 1-Hydroxy-2-naphthoic acid Morifolinobil 7mide, 1.5-
Dihydroxynaphthalene, 2.3-dihydroxynaphthalene, 2.3-dihydroxy-6-sulfanylnaphthalene, 2-human Oxy-3-naphthoic acid morpholinopropylamide, 2-human Oxy-3-naphthoic acid octyl 7mide, 2- Hydroxy-3-naphthoic acid anilide, pencylacetonilide, 1-phenyl-3-methyl-5
-pyrazolone, 1- (2,4,6-dolichloro-O-phenyl)-3-7nilino-5-pyrazolone, 2-[3-α-
(2,5-di-tsrt-7milphenoxy)-butanamidobenz7mido]phenol, 2,4-bis-(benzoyl7cetamino)toluene, 1,3-bis-(pivaloyl7cetaminomethyl)benzene The coupling components can be used alone or in combination of two or more, and any hue can be obtained as required.

A coloring aid may be added to the copying material of the present invention for the purpose of controlling the coloring reaction. As one of the color development aids of the present invention, it is preferable to add a basic substance as necessary for the purpose of making the system basic during thermal development and promoting the coupling reaction.

As these basic substances, used are sparingly water-soluble or water-insoluble basic substances, and substances that generate alkali upon heating.

Basic substances include inorganic and organic ammonium salts,
organic amines, amides, urea and thiourea and their derivatives,
Examples of nitrogen-containing compounds include thiazoles, virols, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidacillines, triazoles, morpholines, piperidines, amidines, form 7 midines, and pyridines. It will be done. Two or more of these basic substances can be used in combination.

In addition, the color development aid of the present invention contains phenol derivatives, naphthol derivatives, flukoxy-substituted benzenes, flukoxy-substituted naphthalenes, human O
Oxy compounds, amide compounds, and sulfonamide compounds can be added. It is thought that these compounds lower the melting point of the coupling component or the basic substance, or improve the heat permeability of the microcapsule wall, resulting in a high degree of color J.

The coloring aids of the present invention also include thermofusible substances.

The heat-melting substance is a substance that is solid at room temperature and has a melting point of 50°C to 150°C and melts by heating, and is a substance that dissolves a diazo compound, a coupling component, or a basic substance. Specific examples of these compounds include fatty acid 7mide, NWL converted fatty acid 7mide, ketone compounds, urea compounds, esters, and the like.

Microcapsules containing the diazo compound or coupling component of the present invention are disclosed in, for example, JP-A-59-190
It can be prepared by the method described in No. 886. The polyurea and polyurethane that form the walls of the microcapsules can be obtained by polymerizing the corresponding monomers by the method described above. , 01 to 0.3. In addition, the diazo compound is 0.05
It is preferable to apply the coating at a rate of ~5.09/m2.

The microcapsules containing the diazo compound of the present invention contain a diazonium salt and the same or different compounds that react with each other to produce a polymeric substance in a nonaqueous solvent with a boiling point of 40°C or more and 95°C or less at normal pressure. After dispersing and emulsifying the dissolved solution in a hydrophilic protective colloid solution, the system is heated while reducing the pressure in the reaction vessel to distill off the non-aqueous solvent and move the wall-forming substance to the oil droplet surface. Substantially solvent-free microcapsules produced by proceeding with a polymer production reaction by polyaddition and polycondensation to form a wall film are particularly preferred in terms of achieving a good shelf life.

In the present invention, the coupling component is 0.1 to 30 parts by weight, and the base pillar substance is 0.1 to 30 parts by weight per 1 part by weight of the diazo compound.
．． It is preferable to use it in a proportion of 1 to 30 parts by weight.

The diazo compound, coupling component, basic substance, and other color development aids that are not encapsulated in the microcapsules used in the present invention are preferably used after being solidly dispersed together with a water-soluble polymer using a sand mill or the like. Preferred water-soluble polymers include water-soluble polymers used when preparing microcapsules (for example, JP-A-59-190
(See No. 886). In this case, each of these compounds is added in an amount of 5 to 40% by weight based on the water-soluble polymer solution. Preferably, the dispersed particle size is 10 microns or less.

A free radical generator (a compound that generates free radicals when irradiated with light) used in photopolymerizable compositions can be added to the copying material of the present invention for the purpose of reducing yellowing of the background after copying. . As free radical generators, aromatic ketones,
Examples include quinones, benzoin, benzoin ethers, azo compounds, organic disulfides, and acyloxime esters. The amount of the free radical generator to be added is preferably 0.01 to 5 parts by weight per 1 part by weight of the diazo compound.

Similarly, for the purpose of reducing yellowing, a polymerizable compound having an ethylenically unsaturated bond (hereinafter referred to as a vinyl monomer) can be used.

Vinyl monomers have at least one ethylenically unsaturated bond (vinyl group, vinylidene group, etc.) in their chemical structure.
It is a compound that has the chemical form of a monomer or a prepolymer. Examples thereof include unsaturated carboxylic acids and their salts, esters of unsaturated carboxylic acids and aliphatic polyhydric alcohols, and 7-mides of unsaturated carboxylic acids and aliphatic polyhydric amine compounds. The vinyl monomer is used in an amount of 0.2 to 20 parts by weight per 1 part by weight of the diazo compound.

It is preferable that the free radical generator and the vinyl monomer are contained in microcapsules together with the diazo compound.

In the present invention, in addition to the above materials, citric acid is used as an acid stabilizer.
Tartaric acid, oxalic acid, boric acid, phosphoric acid, birophosphoric acid, etc. can be added.

The copying material of the present invention is prepared by preparing microcapsules containing a diazo compound or a cambling component, and a coating solution containing a basic substance and other additives, and applying the coating solution onto a support such as paper or a synthetic resin film. coating, blade coating,
The photosensitive layer is coated and dried by a coating method such as air knife coating, gravure coating, roll coating, spray coating, dip coating, or curtain coating to form a photosensitive layer having a thickness of 2.5 to 30 q/m2. The copying material of the present invention may have a laminated structure in which the diazo compound, coupling component, base, etc. may be contained in the same layer as described in the above method, or may be contained in separate layers. You can also do it. It is also possible to provide an intermediate layer on the support as described in Japanese Patent Application No. 177,669/1980, and then coat the photosensitive layer.

As the support of the present invention, any filter paper support used for ordinary pressure-sensitive paper, thermal paper, dry or wet diazo copying paper, etc. can be used, as well as neutral sizing agents such as alkyl ketene dimer. Neutral paper with a pH of 6 to 9 (described in Japanese Patent Application No. 55-14281) sized by paper with an optical surface roughness of 8μ or less and a thickness of 30 to 150μ as described in JP-A No. 58-138492, a paper with a density of 0.99/n as described in JP-A-58-69091 cm
Paper with optical contact rate of 15% or more under 3M, JP-A-5
Canadian Standard Freeness (JIS) as described in No. 8-69097
P8121) Paper made from pulp beaten to 400cc or more to prevent coating liquid from seeping in, JP-A-58
-65695, the glossy side of base paper made by a Yankee machine is used as the coating surface to improve the color density and resolution, and the base paper described in JP-A-59-35985 is subjected to corona discharge treatment to improve coating suitability. Improved paper can also be used.

Further, the synthetic resin film used as a support in the present invention can be arbitrarily selected from known materials that do not deform even when heated during the development process and have dimensional stability. Examples of such films include polyester films such as polyethylene terephthalate and polybutylene terephthalate, cellulose derivative films such as cellulose triacetate films, polystyrene films, polypropylene films, and polyolefin films such as polyethylene. Can be used. The thickness of the support is 20 to 200
μ is used.

The following method is preferred for forming an image on the copying material of the present invention. In the first step of performing exposure corresponding to the image of the original to form a latent image on the photosensitive layer and fixing areas other than the image forming area by light irradiation, the light source for exposure may be a fluorescent lamp, a xenon lamp, a mercury lamp, etc. is used, and it is preferable that the emission spectrum substantially matches the absorption spectrum of the diazo compound used in the copying material, since it is possible to efficiently stabilize the light in areas other than the image forming area. 6 of the present invention
An example of a method for exposing to light in a temperature range of 0°C to 80°C is to wrap copying material overlapping a document directly around a fluorescent lamp, expose it, and then convey it. The temperature inside the glass tube is cooled by controlling it by forced air, or by inserting various light sources into a transparent glass tube, wrapping the glass tube with the copy material overlapping the original, exposing it to light, and then transporting it. Methods such as controlling by blowing air are preferably used.

In addition, in the second step of heating and developing the entire surface of the photosensitive layer of the material, the heating means may include a thermal pen, a thermal head,
Infrared rays, high frequency waves, heat blocks, heat rollers, etc. can be used.

As described above in detail, the present invention has realized a copying material and an image forming method that have a good shelf life and can provide high color density even when subjected to low-temperature thermal development. The temperatures in the first and second heating steps are arbitrarily determined depending on the characteristics of the materials used, such as the diazo compound and coupling components, and the development conditions.
In the exposure process, the temperature at which the recorded image formation reaction does not occur is 60°C.
The temperature is preferably from 80°C to 80°C, and in the second heating step, the minimum temperature necessary for the recorded image forming reaction to occur is preferably from 80°C to 150°C. In addition, it is preferable that the recording material is kept warm between the first step and the second step. If the recording material is not kept warm, the recording material is transferred from the first step to the second step within 60 seconds. Preferably, the recording material is moving.

EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples.

<Example> 3.45 parts of 1-morpholino-2,5-dibutoxybenzene-4-diazonium hexafluorophosphate, xylylene diinocyanate and trimethylolpropane (3.45 parts)
: 1) 18 parts of the adduct were added to a mixed solvent of 6 parts of tricresyl phosphate and 5 parts of ethyl acetate, and dissolved by heating. This diazo compound solution was mixed with an aqueous solution containing 5.2 parts of polyvinyl alcohol dissolved in 58 parts of water, and emulsified and dispersed at 20°C to obtain an emulsion having an average particle size of 2.5 μm. 100 parts of water was added to the obtained emulsion and heated to 60°C while stirring, and after 2 hours, a capsule liquid containing the diazo compound in the core substance was obtained.

Next, 10 parts of 2-hydroxy-3-naphthoic acid anilide and 10 parts of triphenylguanidine were added to 200 parts of a 5% polyvinyl alcohol aqueous solution and dispersed in a sand mill for about 24 hours to obtain a dispersion having an average particle size of 3 μm.

To 50 parts of the capsule solution of the diazo compound obtained as described above, 50 parts of a dispersion of a coupling component and triphenylguanidine and 10 parts of a 40% calcium carbonate dispersion were added to prepare a coating liquid. Spread this coating solution on smooth high-quality paper (7
5c+/m2) using a coating bar to dry weight 1
Copying material A was prepared by coating at a concentration of 0 g/m2 and drying at 50°C for 1 minute.

A fluorescent lamp with a diameter of 55 mm with a maximum emission spectrum of 420 nm was used in the exposure section, and the copying material was wrapped around it at an angle of 270° and exposed and conveyed.
An apparatus for heating and conveying copying material by wrapping it around a 2700 mm heat roller was created. A path of 300 mm was provided between the exposure section and the heat development section. Wind at a constant temperature is always forced to the tube wall of the fluorescent lamp in the exposed area, and the temperature of the tube wall can be controlled by the temperature of this wind.

An image was formed on the above copy material using the above apparatus.

Copy material A was overlaid with a test original (a circle 3 cm in diameter painted uniformly black on tracing paper with a 2B lead lid) and exposed. At this time, the illuminance of the fluorescent lamp is set to lOmW.
/am2 (Illuminance meter IJVD-4 manufactured by Ushio Electric Co., Ltd.
05PD), and the conveyance speed was set to 30 mm/sea. Fluorescent tube wall temperature: 50℃, 60℃, 70℃
, 80℃, 90℃, and set the heat roller temperature to 1.
Images were formed at temperatures of 00°C, 120°C, and 140°C. Table 1 shows the results of measuring the colored area and background area using a Macbeth J meter. Similar test at 40℃90%RH3
The test was also carried out on copying materials after being stored for several days, and the results are shown in Table 2.

According to Tables 1 and 2, by using the image forming method of the present invention, it is possible to reduce the heat development temperature by approximately 20°C to 40°C while maintaining a good shelf life as a copying material. I understand that there is something.

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Claims (1)

[Claims] A copying material provided with a heat-developable photosensitive layer containing a diazo compound and a coupling component, at least one of which is encapsulated in microcapsules, on a support is exposed to light corresponding to the image of the original, and the photosensitive layer is exposed to light corresponding to the image of the original. An image forming method comprising a first step of forming a latent image on the layer and fixing the area other than the image forming area by irradiation with light, and a second step of developing by heating, wherein the first step is 60℃～
An image forming method characterized by exposing at a temperature range of 80°C.