JPH01310347A - Thermal development type copying material - Google Patents

Abstract

PURPOSE:To make it possible to obtain the high color density of the title material, even in case of developing the material at a low temp. by mounting further a protective layer on a photosensitive layer which is capable of applying a thermal development to the material and contains a diazo compd., a coupling component and a color auxiliary agent. CONSTITUTION:The photosensitive layer contg. the diazo compd., the coupling component and the auxiliary agent is mounted on a supporting body, and further, the protective layer incorporated a latex having the min. film forming temp. of >=60 deg.C is mounted on the protective layer. And, any one of the diazonium compd. and the coupling component is enclosed in a microcapsule composed of a polyurethane or a polyurea. The copying material obtd. by the method as mentioned above, is exposed corresponding to an original, and a light irradiates a part except the image forming part of the copying material, followed by heating and developing the whole surface of the photosensitive layer. Thus, the high color density of the copying material is obtd., even in case of developing the material at the low temp.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a copying material, particularly a heat-developable copying material with high surface gloss and improved film surface strength.

<Prior Art> There are three types of copying materials that utilize the photosensitivity of diazo compounds. One 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 with an alkaline solution. The second type is known as a dry development type, which differs from the wet type in that development is performed using 7 ml 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 ammonia gas by heating in the photosensitive layer, and a type that contains 8990 nitrate acetic 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 developer as it uses a developer 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 make additions immediately. There are several problems such as copy images not being able to withstand long-term storage. In addition, like the wet type, the dry type requires replenishment of developer, requires gas absorption equipment to prevent the generated ammonia gas from leaking outside, and therefore requires larger equipment.
I have problems such as the smell of 7mm smell immediately after copying. On the other hand, unlike the wet and dry types, the heat-developable type has the advantage of maintenance because it does not require a developer, but all conventional types require a high developing temperature of 1506°C to 200°C. Moreover, if the temperature is not controlled to about ±+o'c, there will be insufficient development or changes in color tone, resulting in a problem of increased equipment cost. Further, the diazo compound used for such high-temperature development is required to have high heat resistance, but such compounds are often disadvantageous in forming a high J degree. Low temperature development (90°C to 130°C
) have been attempted, but 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 copying material is provided with a heat-developable photosensitive layer containing a diazo compound, a coupling component, and a coloring aid on a support. It was discovered that one basic solution is to contain at least one of the diazo compound or the coupling component in microcapsules. However, these microcapsules are easily destroyed by physical strain applied to the coating film, such as pressure, as is conventionally used in pressure-sensitive paper. There was still a need for ways to suppress the destruction of the capsules due to the dry shrinkage force of the coating film, which can occur during the process of coating and drying to obtain a product.

The destruction of microcapsules appears as a phenomenon of discoloration of the skin. Therefore, in order to maintain the quality of copied images necessary for copying materials, it is necessary to improve the coating film composition, increase surface gloss, improve image sharpness, and increase coating film strength. This would not have been possible without finding a way to prevent the capsule from rupturing.

Therefore, a first object of the present invention is to provide a copying material that can obtain high color density even by low-temperature development.

A second 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.

A third object of the present invention is to provide a copying material that has high image clarity and excellent long-term storage stability (small decrease in color density and small increase in background density when stored in bright and dark places). It is in.

A fourth object of the present invention is to provide a copying material with excellent water resistance, chemical resistance, and abrasion resistance.

A fifth object of the present invention is to provide a simple and easy-to-maintain image forming method that uses the copying material described above and combines a latent image formation process by exposure and a development process by heating.

Means for Solving the Problems> The above aspects of the present invention provide a recording material in which a heat-developable photosensitive layer containing a diazo compound, a coupling component, and a coloring aid is provided on a support, This has been achieved by a heat-developable copying material characterized in that a protective layer containing latex having a minimum film-forming temperature of 60° C. or higher is further provided on the photosensitive layer. At this time, at least one of the diazo compound and the coupling component is contained in the microcapsule, and the wall of the microcapsule is formed of at least one kind of polymer selected from polyurethane and polyurea. It is preferable.

Conventionally, when latex is used as a recording material, a binder with a minimum film forming temperature (MFT) of 20°C or less has been used to improve coating film strength and water resistance. . This is because a continuous film of latex must be formed during application, drying, or during storage, and for this purpose it is necessary to use a material with a low MFT.

However, since a large strain was applied to the capsule of the present invention during this film-forming process, the contents oozed out from the capsule and a coloring reaction occurred, resulting in skin discoloration. The present inventors have arrived at the present invention as a result of intensive studies to solve this problem.

The copying material of the present invention has a minimum film forming temperature of 60°C in advance.
Either the above latex is added to the protective layer coating solution and applied at the same time as the photosensitive layer is applied, or the photosensitive layer is applied and then the protective layer is applied after drying. Manufactured by At this time, an intermediate layer may be provided between the photosensitive layer and the protective layer, if necessary, as long as it meets the purpose of the present invention. This coating and drying process is the same as when manufacturing normal thermal recording paper.
The surface temperature of coated paper is 50℃ to prevent fogging.
Since drying is controlled to be as follows, latex with an MFT of 60°C or higher in the protective layer cannot form a unique continuous film and remains as white fine particles of 0.1 to 0.3μ. Therefore, no distortion occurs due to film formation.

In the present invention, a copying material manufactured through a process of coating and drying is first exposed to light corresponding to the image of the original to form a latent image on the photosensitive layer, and at the same time, areas other than the image-formed area are fixed by light irradiation. In other words, the background of the copy material (non-image area)
There are no longer any diazo compounds capable of color reaction.

In the present invention, an image is formed by developing the photosensitive layer after exposure by heating the entire surface, but if the temperature during this heating is set above the MFT of the latex of the present invention, a continuous film peculiar to latex can be formed at the same time as development. You can make it happen. In this process, the color of the background layer due to distortion no longer occurs.

In the present invention, as a means for heating the entire surface of the photosensitive layer, for example, a thermal pen, a thermal head, an infrared ray, a high frequency, a heat block, a heat roller, etc. can be used. The heating temperature at this time needs to be higher than the MFT of the latex used, and is preferably 60°C or higher and 180°C or lower. If it is below 60°C, a continuous latex film will not be formed, and if it is above 180°C, it will not meet the purpose of low-temperature development of the present invention.

Various types of fluorescent lamps, xenon lamps, mercury lamps, etc. are used as light sources for exposure in the present invention, and the fact that this emission spectrum almost matches the absorption spectrum of the diazo compound used in the copying material is that This is preferable because it allows efficient optical fixation.

Examples of the latex with an MFT of 60°C or higher used in the present invention include SBR, MB, which is obtained by a known polymerization method.
Synthetic rubber latex such as R, MSB, NE3R, CR, IR and polybutadiene.

Examples include emulsion latexes such as vinyl acetate emulsions, vinyl acetate-ethylene emulsions, and acrylic acid ester emulsions, vinyl chloride latexes, and the like.

As mentioned above, the glass transition temperature of these polymer latexes is required to be 60° C. or higher.

In the above polymer latex, SBR latex contains styrene-butadiene, MBR latex contains methyl methacrylate and butadiene, MSB latex contains methyl methacrylate, styrene and butadiene, SBR latex contains 7-crylonitrile and butadiene, CR latex uses chloroprene, IR latex uses isoprene, polybutadiene latex uses butadiene, vinyl acetate emulsion latex uses vinyl acetate, and vinyl acetate-acrylic emulsion uses vinyl acetate and acrylic esters (methyl, ethyl, butyl, 2-ethylhexyl, etc.) as the main raw material. however,
In addition to these main raw materials, the following monomers that can be copolymerized with these can also be used to improve the physical properties of the resulting polymer latex, and the polymer latex improved using these materials is also subject to the present invention. It goes without saying that it can be used as a polymer latex for the invention.

That is, monomers that can be copolymerized with the main raw material of each of the polymer latexes mentioned above include the following, but these are just examples, and there are other monomers that can be copolymerized with the main raw material. All monomers can be used. These monomers for improving physical properties may be copolymerized with polymer latex in advance, or in some cases, they may be copolymerized with water-soluble vinyl monomers in the presence of polymer latex. You may. Such monomers include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, crotonic acid, conjugated diolefins such as butadiene, isoprene, chlorobrene, styrene, methyl Aromatic vinyl compounds such as styrene and α-methylstyrene, methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, and 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, and butyl acrylate. , acrylic acid esters such as 2-ethylhexyl acrylate, 7-crylonitrile, ethylene-based nitrile compounds such as methacrylonitrile, β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, acrylic 7mide, methacryl 7 Mido, N-methylolacryl 7mido, N-methylolmethacryl 7mido, N
- wood-philic monomers such as butoxymethylacrylamide, glycidyl acrylate, glycidyl methacrylate, vinyl acetate, vinyl chloride, vinylidene chloride, and the like.

For example, in the case of SBR latex made from styrene-butadiene, if the amount of bound styrene is 80% or more, the MFT will be 60° C. or more, which can be the latex targeted by the present invention.

Furthermore, in the case of acrylic latex, it is possible to easily obtain an MFT of 60° C. or higher by copolymerizing with a polymer having a high T9 such as polymethyl methacrylate.

By selecting the type of monomer to be bonded and adjusting its ratio, the desired MFT can be easily achieved at 60°C.
or more latex can be obtained.

The amount of latex used in the present invention is about 3% to 80% by weight of the solid content of the protective layer, preferably about 5% to 50% by weight.

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 down 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)) In other words, when a diazo compound is used as a photodegradable compound, its chemical structure It is decomposed using light of a specific wavelength depending on its structure. Furthermore, by changing the chemical structure of the di7zo compound, it is possible to change the hue of the dye after the reaction 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, A r l represents a substituted or unsubstituted aromatic ring, N2 represents a diazonium group, and X represents an acid 7 ion.) In the present invention, the photolysis wavelength is different or the photolysis rate is different. By using diazo compounds having different values, a multicolor heat-developable copying material can be obtained.

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-dimethyl 7-minobenzene, 4-diazo-1-methylbenzyl 7-minobenzene, 4-diazo-1-ethylhydroxyethyl 7-minobenzene , 4-diazo-1-diethyl 7 minnow 3-methoxy
Sibenzene, 4-diazo-1-morpholinobenzene, 4
-Diazo-1-morpholino-2,5-dibutoxybenzene.

4-Diazo-1-tolylmercapto-2,5=diethoxybenzene, 4-diazo-1-piperazino-2-methoxy-5-chlorobenzene, 4-diazo-1-(N,N
-dioctyl7minocarponyl)benzene, 4-diazo-1(4-tart-octylphenoxy)benzene,
4-Diazo-1-(2-ethylhexanoylpiperidino)-2゜5-dibutoxybenzene, 4-diazo-1-(
2゜5-di-tert-7milphenoxyα-butanoylpiperidino)benzene, 4-diazo-1-(4-methoxy)phenylthio-2,5-jethoxybenzene,
4-diazo-1-(4-methoxy)benz7mido2,
5-Jethoxybenzene, 4-diazo-1-piOlisino-2-methoxybenzene Specific examples of acids that form diazonium salts with the above-mentioned diazo compounds include the following.

c,, F2n+1COOH (n is an integer from 1 to 9), C4
F2M+ISOcoH (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 component used in the present invention is one that forms a dye by coupling with a diazo compound in a basic atmosphere, and includes so-called active methylene compounds having a methylene group next to a carbonyl group, phenol derivatives, There are naphthol derivatives, and specific examples include the following.

Resorcinol, phloroglucin, sodium 2,3-dihydroxynaphthalene-6-sulfonate, 1-hydroxy-2-naphthoic acid morifolinobuchipil 7mide, 1,5-
Dihydroxynaphthalene, 2.3-dihydroxynaphthalene, 2.3-dihydroxy-6-sulfanylnaphthalene, morpholinopropyl 2-hydroxy-3-naphthoate 7mide, octyl 2-hydroxy-3-naphthoate 7mide, 2-human O xy-3-naphthoic acid anilide, benzoyl 7cetonylide, 1-phenyl-3-methyl-5
-pyrazolone, 1-(2,4,6-drichlorophenyl)-3-7nilino-5-pyrazolone, 2-[3-α-
(2,5-di-tart-amylphenoxy)-butanamidobenzamide]phenol, 2,4-bis-(benzoyl7ceto7mino)toluene, 1,3-bis-(pivaloylacetaminomethyl)benzene These coupling components can be used alone or in combination of two or more, and any hue can be obtained as required.

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, 7mide, urea and thiourea and their derivatives,
Examples of nitrogen-containing compounds include thiazoles, pyrroles, 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 coloring aids of the present invention include phenol derivatives, naphthol derivatives, flukoxy-substituted benzenes, alkoxy-substituted naphthalenes, hydroxy compounds, amide compounds, sulfonamide compounds can be added. These compounds are thought to lower the melting point of the coupling component or the basic substance, or to improve the thermal permeability of the microcapsule wall, resulting in a high color density.

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

The heat-melting substance is a substance that is normally solid 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 acids 7
Examples include mido, N-substituted fatty acid 7mido, ketone compounds, urea compounds, and esters.

Microcapsules containing the diazo compound and coupling component of the present invention are disclosed in, for example, JP-A-59-190886.
It can be prepared by the method described in No. Furthermore, the purpose of the present invention is to create microcapsules that are substantially free of solvent by dissolving a diazo compound or a coupling component together with a capsule wall-forming monomer in a low-boiling non-aqueous solvent, and distilling off the solvent while carrying out a polymerization reaction. It is preferable to use The polyurea and polyurethane that form the walls of the microcapsules can be obtained by polymerizing the corresponding monomers by the method described above. It is determined to be between .01 and 0.3.

Moreover, it is preferable to apply the diazo compound at a rate of 0.05 to 5.0 q/m'.

In the present invention, the coupling component is 0.1 to 30 parts by weight and the basic 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 contained 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-59-19
(See No. 0888). In this case, the diazo compound, coupling component, and coloring aid are each added in an amount of 5 to 40 times the center of gravity of the water-soluble polymer solution.

Preferably, the dispersed particle size is 10 microns or less.

A free radical generator (a compound that generates 'tE leaving groups when irradiated with light) used in photopolymerizable compositions may be added to the copying material of the present invention for the purpose of reducing yellowing of the background after copying. I can do it. Examples of free radical generators include aromatic ketones, quinones, benzoin, benzoin ethers, 7
Examples include zo compounds, organic disulfides, and 7-syloxime esters. The amount to be added is 1 diazo compound
It is preferable that the amount of the J-free group generating agent is 0.01 to 5 parts based on the weight part.

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 particularly 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, pyrophosphoric acid, etc. can be added.

The copying material of the present invention can be prepared by preparing a coating solution containing a diazo compound, a coupling component, a basic substance, and other additives, and applying the coating solution onto a support such as paper or a synthetic resin film by bar coating, blade coating, or air knife coating. The photosensitive layer is coated and dried by a coating method such as coating, gravure coating, roll coating, spray coating, or dip coating to form a photosensitive layer having a thickness of 2.5 to 309/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.

In the present invention, materials for the protective layer that can be used in combination with latex with an MFT of 60°C or higher include various water-soluble (elbow fat, water-based emulsion, solvent-soluble type (elbow fat, water-soluble resin) Examples of aqueous emulsions include polyvinyl alcohol, starch, casein, gelatin, hydroxyethyl cellulose, methyl cellulose, polyvinyl bi-Olidone, styrene-maleic anhydride copolymer salt, and aqueous emulsions such as polyacrylic ester, polymethacrylic ester, polyvinyl acetate, Examples include vinyl acetate copolymers and vinyl chloride copolymers, and commonly known solvent-soluble 1i resins such as polystyrene, polymethyl methacrylate, polyethyl methacrylate, polyester, and ethyl cellulose can be used.

In addition, calcium carbonate, aluminum hydroxide, silica, kaolin, etc. are added to the protective layer to prevent stickiness.
It is also possible to add various pigments such as talc, clay, zinc oxide, titanium oxide, starch, and urea-melamine resin fine powder.

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. 58-136492, a paper with a density of 0.99/2 as described in JP-A-58-69091 cm
' Paper with an optical contact rate of 15% or more, Canadian standard freeness (JIS
Paper made from valves beaten to 400 cc or more with P8121) to prevent coating liquid from seeping in, JP-A-5
8-65695, the glossy side of a 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. Paper improved on can also be used.

Further, the synthetic resin film used as the support in the present invention can be arbitrarily selected from known materials that are dimensionally stable and less deformed by heating during the development process. Examples of such films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polycarbonate, cellulose derivative films such as cellulose triacetate film, polystyrene film, polyolefin film such as polyethylene pyrene film, polyolefin film such as polyethylene, and polyimide film. , these can be used alone or in combination. The thickness of the support used is 20 to 200 microns.

<Effects of the Invention> As detailed above, the copying material of the present invention has a MF of 760°C.
Since the above latex is contained in the protective layer, a film unique to latex covers the surface after heat development, increasing scratch resistance and water resistance, and increasing the gloss of the surface, resulting in high quality images with high sharpness. I was able to obtain a certain image. Moreover, since the capsule of the present invention is prevented from being damaged by physical distortion during the latex film formation process, it has become possible to achieve the above characteristics while maintaining a good shelf life.

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 diisocyanate 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 the mixture was heated to 60° C. while stirring. After 2 hours, a capsule liquid containing a diazo compound in the core substance was obtained.

Next, 10 parts of 2-hydroxy-3-naphthoic acid 7nylide 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 with 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
59/m2) using a coating bar to dry weight 10
Copying material A was prepared by applying the coating at a coating density of 9/m2 and drying at 50°C for 1 minute.

On the other hand, a coating solution for the protective layer is prepared by mixing 100 parts of 5% polyvinyl alcohol and 5 parts of a 40% calcium carbonate dispersion, and is coated on copying material A with a dry weight of 2.
Copying material B was prepared by applying the coating using a coating bar so as to give c+/m2 and drying at 50° C. for 1 minute.

In addition to the above coating solution for the protective layer, MFT was added to 45% by weight at 0°C5.
A solution containing 6 parts of E3R latex (containing 60% bound styrene) was prepared and coated on copy material A in the same manner as copy material B to prepare copy material C. Similarly, SBR latex (bonded styrene 83
%), and copy material E was prepared using methyl methacrylate latex with an MFT of 100°C.

Test manuscript on copy materials A-H (a circle with a diameter of 3 cm painted uniformly black on tracing paper with a 2B pencil)
was placed on top and exposed to fluorescent light. At this time, a fluorescent lamp whose emission spectrum has a maximum value at 420 nm was used. Next, an image was formed by heating for 3 seconds using a heat block heated to 120°C. In the same way,
Heat block temperatures of 100°C and 1160°C were also tested. In addition, to test the shelf life, the sample was stored at 40'C, 90% RH for 24 hours, exposed to light in the same manner, and developed at 120°C. 60”02 at 30%RH
A 4-hour storage test was also conducted. The density of the colored part and the background part of the sample obtained in each test was measured using a Macbeth A meter.

Table 1 shows the results of tests at different heating temperatures, and Table 2 shows the results of the pre-copy storage test.

As shown in Table 1, an increase in color density was observed by optical density measurement due to the increased surface gloss due to the latex film. Furthermore, an increase in skin density was observed in latex with low MFT.

The * mark in the table indicates a sample tested as a comparative example for the present invention.

~that's all~

Claims (1)

[Claims] 1) A recording material in which a heat-developable photosensitive layer containing a diazo compound, a coupling component, and a coloring aid is provided on a support, and a protective layer is further provided on the photosensitive layer. A heat-developable copying material characterized by: 2) The heat-developable copying material according to claim 1, wherein a latex having a minimum film-forming temperature of 60° C. or higher is added to the protective layer. 3) At least one of the diazo compound and the coupling component is contained in the microcapsule,
2. The heat-developable copying material according to claim 1, wherein the walls of the microcapsules are made of at least one polymer selected from polyurethane and polyurea. 4) A step of exposing the copying material according to claim 1 to light corresponding to the image of the original to form a latent image on the photosensitive layer, and fixing the area other than the image forming area by light irradiation, and the exposure step. An image forming method comprising the step of subsequently heating and developing the entire surface of the photosensitive layer of the copying material.