JPH0222647A - Heat developable copying material - Google Patents

Abstract

PURPOSE:To obtain high color development density even by low temperature development by forming an interlayer containing a film-forming polymer binder and at least one of inorganic and organic pigments between a support and a photosensitive layer. CONSTITUTION:The interlayer containing the film-forming polymer binder A and at least one B of the inorganic pigment and the organic pigment in a weight ratio of 1:0-1:20, preferably, 1:3-1:10 is formed in a total amount of 1-15g/m<2>, preferably, 3-10g/m<2> between the support and the photosensitive layer, and at least one of a diazo compound and a coupling component is contained in microcapsules, and their shells are made of polyurea or poly-urethane, thus permitting high color development density to be obtained even by the low temperature development.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a copying material, particularly a heat-developable copying material that utilizes the photosensitivity of a diazo compound (diazonium salt). More specifically, the present invention relates to a high-quality heat-developable copying material with little density unevenness in copied images.

<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 ammonia gas by heating in the photosensitive layer, or a type that contains trichloroacetic acid in the photosensitive layer. There are types that contain an alkali salt of an acid that loses its properties as an acid when heated, and types that use a higher fatty acid amide as a coloring aid and activate the diazo compound and coupling component 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.
There are problems such as the smell of ammonia immediately after copying. On the other hand, unlike the wet and dry types, the thermal development type has the advantage of maintenance because it does not require a developing solution. Moreover, if the temperature is not controlled to about ±10° C., insufficient development or changes in color tone occur, resulting in an increase in 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. 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 side 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 is instantaneously melted and diffused by heating. It is necessary to react to produce a colored pigment. 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.

On the other hand, the color density of a heat-developable copying material is determined by the applied thermal energy and the amount of colorable components.

In particular, as the developing temperature is lowered, highly efficient heat transfer from the heating means and generation of a more uniform amount of coloring dye become essential requirements for obtaining high quality copy images. In other words, unevenness on the surface of the copying material may cause uneven heating in some areas, resulting in uneven formation of the amount of coloring dye, or unevenness in the surface of the support may cause unevenness in the amount of colorable components in some areas. Therefore, it is necessary to prevent density unevenness in the copied image due to non-uniform production of the amount of coloring dye after heating.

In the present invention, the microcapsules invented to achieve both shelf life and thermal sensitivity have the problem of being susceptible to the unevenness of the support surface as described above because they exist as fine particles in the membrane. In addition, in the case of paper supports, there is also the problem of non-uniformity due to penetration, and therefore it has not been possible to prevent density unevenness in copied images.

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 high-quality copying material with fewer image quality deterioration factors such as density unevenness.

A fourth 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 copying 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 was achieved by a heat-developable copying material characterized in that an intermediate layer containing a film-forming polymer binder and at least one of an inorganic pigment and an organic pigment is provided between the support and 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 polyurea and polyurethane. It is preferable.

The film-forming polymer binder used in the intermediate layer of the present invention includes water-soluble polymers and water-insoluble polymers, and may be used individually or in combination of two or more types.

Examples of water-soluble polymers include methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, starches, gelatin, gum arabic, casein, styrene-maleic anhydride copolymer hydrolyzate, ethylene-maleic anhydride copolymer hydrolyzate, and isobutylene. -Maleic anhydride copolymer hydrolyzate, vinyl acetate-maleic anhydride copolymer hydrolyzate, vinyl methyl ether-maleic anhydride copolymer hydrolyzate, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, silicon-modified polyvinyl alcohol , polyacryl 7mide, polyvinylpyrrolidone, sodium alginate, and the like.

As water-insoluble polymers, synthetic rubber latex or synthetic resin emulsion is generally used, such as styrene-butadiene rubber latex, 7-crylonitrile-butadiene rubber latex, methyl acrylate-butadiene rubber latex, polyvinyl acetate emulsion, Examples include polyacrylic emulsion, polyester emulsion, and polyurethane emulsion.

Inorganic or organic pigments used in the intermediate layer of the present invention include kaolin, calcined kaolin, talc, calcium carbonate, amorphous silica, barium sulfate, aluminum hydroxide, titanium oxide, waxite, urea-formalin, and powder,
Polyethylene water-soluble fine powder, polystyrene fine powder, etc. are included, and the oil absorption as specified by JIS-5101 is 40c.
Those having a whiteness of c/1009 or more are preferred, and among these pigments, those having a whiteness of 85% or more are more preferred.

In addition, waxes such as polyethylene wax, carnauba wax, paraffin wax, microcrystalline wax, fatty acid amide, metal soaps such as zinc stearate and calcium stearate, surfactants, etc. may be added to the intermediate layer as necessary. good.

The ratio of binder and pigment in the intermediate layer of the present invention is 0 to 1:20 by weight. Preferably it is in the range of 1:3 to 1:10, and the total coating amount is 1 to 159/m2%, preferably 3 to 1o9/m2.

When the coating amount is less than this, the effect is small, and when it is more than this, curling after development becomes large, which is not preferable.

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 diazo-7mino 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, A" represents a substituted or unsubstituted aromatic ring, and N
2 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-dimethyl 7-minobenzene, 4-diazo-1-methylbenzylaminobenzene, 4-diazo-1-ethylhydroxyethyl 7-minobenzene, 4-Diazo-1-diethylamino-3-methoxy
Sibenzene, 4-diazo-1-morpholinobenzene, 4
-Diazo-1-morpholino-2,5-dibutoxybenzene.

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

C, F2n+, C00H (n is an integer from 1 to 9), C.

F2m+, 5O3H (m is an integer of 1 to 9) L boron tetrafluoride, tetraphenylboron, hexafluorophosphoric acid,
Aromatic carboxylic acids, aromatic sulfonic acids.

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, phloroglucin, sodium 2,3-dihydroxynaphthalene-6-sulfonate, 1-hydroxy-2-naphthoic acid molyborinopropylamide, 1,5-
Dihydroxynaphthalene, 2.3-dihydroxynaphthalene, 2.3-dihydroxy-6-sulfanylnaphthalene, 2-hydroxy-3-naphthoic acid morpholinopropylamide, 2-hydroxy-3-naphthoic acid octyl 7mide, 2-hydroxy- 3-naphthoic acid 7nylide,
Pencylacetonilide, 1-phenyl-3-methyl-
5-pyrazolone, +-(2,4,6-drichlorophenyl)-3-7nilino 5-pyrazolone, 2-[3-α-
(215-di-tert-amylfe/xy)-butane7midobenz7mido]phenol, 2,4-bis-(benzoylaceto7mino)toluene, 1,3-bis-(pivaloyl7ceto7minomethyl)benzene These cups The ring 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,
Thiazoles, virols, pyrimidines, piperazines, guanidines, indoles, imidazoles, imidacillins, triazoles, molevorin,
Examples include nitrogen-containing compounds such as piperidines, 7midines, form 7midines, and pyridines. 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, alkoxy-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 having a melting point of 50°C to 150°C that is solid at room temperature 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 amides, 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.

Further, it is preferable to apply the diazo compound at 0.05 to 5.09/m2.

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-59-190
(See No. 886). In this case, the diazo compound, coupling component, and coloring aid are each 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 salts thereof, esters of unsaturated carboxylic acids and aliphatic polyhydric alcohols, amides of unsaturated carboxylic acids and aliphatic polyhydric amine compounds, and the like. 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 produced by preparing a coating solution for the intermediate layer of the present invention and a coating solution for the photosensitive layer containing a diazo compound, a coupling component, a basic substance, and other additives. Bar coating, blade coating, air knife coating, gravure coating, sequentially or simultaneously on the support of
It is applied by a coating method such as roll coating, spray coating, dip coating, curtain coating, etc. and dried to form an intermediate layer with a solid content of 1 to 159/m2 and a solid content of 2.5 to 309/m2.
A photosensitive layer is provided. 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.

As the support of the present invention, any paper support used for ordinary pressure-sensitive paper, thermal paper, dry or wet diazo copying paper, etc. can be used, and in addition, neutral sizing agents such as alkyl ketene dimers can be used. Sized neutral paper with a pH of 6 to 9 (described in Japanese Patent Application No. 14281/1983), which satisfies the relationship between Steckigt sizing degree and metric basis weight described in Japanese Patent Application Laid-open No. 116687/1982, and has Bekk smoothness. 90 seconds or more paper, paper with an optical surface roughness of 8μ or less and a thickness of 30 to 150μ as described in JP-A-58-138492, density 0.9 g/cm as described in JP-A-58-89091
Paper with an optical contact ratio of 3 or less and an optical contact ratio of 15% or more, JP-A-5
Canadian Standard Freeness (JIS) as described in No. 8-69097
P8121) Paper made from valves beaten to 4000C or higher 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 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 films, polystyrene films, polypropylene films, polyolefin films such as polyethylene, and polyimide films. It can be used alone or in combination. The final thickness of the support used is 20 to 200 .mu.m.

The following method is preferred for forming an image on the copying material of the present invention. In the process of forming a latent image on the photosensitive layer by exposing it to light corresponding to the image of the original, and fixing areas other than the image forming area by light irradiation, various fluorescent lamps, xenon lamps, mercury lamps, etc. are used as the light source for exposure. It is preferable that the emission spectrum substantially matches the absorption spectrum of the diazo compound used in the copying material, since areas other than the image forming area can be efficiently optically fixed. Further, in the step of heating and developing the entire photosensitive layer of the material, a thermal pen, a thermal head, an infrared ray, a high frequency, a heat block, a heat roller, etc. can be used as the heating means.

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 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 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
5q/m2) using a coating bar to dry weight 10
Copying material A was prepared by applying the coating to a coating density of 9/m2 and drying at 500C for 1 minute.

On the other hand, an interlayer-coated paper for copying material 8% C was made using the above-mentioned high-quality paper.

Copying material daily paper: using calcined kaolin as pigment, 80
part was dispersed in a homogenizer with 160 parts of a 0.5% aqueous solution of sodium hexametaphosphate.

A coating solution obtained by adding 10 parts of 48% styrene-butadiene latex to 60 parts of this dispersion has a solid content of 69 parts m2.
Apply it and let it dry.

Copying material C paper: An intermediate layer-coated paper was prepared in the same manner as above, except that in the intermediate layer for copying material B, slight calcium carbonate was used instead of calcined kaolin.

Using the above paper, copy material B in the same manner as copy material A.
%C was created.

A test original (a circle with a diameter of 3 cm painted uniformly black on tracing paper with a 2B'#Q brush) was placed on copy materials A to C and exposed to light from a fluorescent lamp. At this time, a fluorescent lamp with an emission spectrum having a maximum value of 420 nm was used. Next, an image was formed by heating for 3 seconds using a heat block heated to 120°C. Similarly, the heat block was tested at temperatures of 100°C and 160°C. 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. 60'030%RH
We also conducted a 24-hour storage test. The densities of the colored parts and background parts of the samples obtained in each test were measured using a Macbeth densitometer.

In addition, for image quality evaluation, copying materials A to C were passed through a heat roller adjusted to 90° C. without being exposed overlappingly with a test original to make a solid sample, and density unevenness was observed. Table 3 shows the results of visual observation.

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

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

As can be seen from Tables 1 to 3, the copying material provided with the intermediate layer of the present invention maintains a good shelf life, obtains high color density even through low-temperature thermal development, and achieves high image quality without density unevenness. was recognized as doing so.

~that's all~

Claims (1)

[Scope of Claims] 1) A copying material in which a heat-developable photosensitive layer containing a diazo compound, a coupling component, and a coloring aid is provided on a support, in which a photosensitive layer is provided between the support and the photosensitive layer. A heat-developable copying material comprising an intermediate layer containing a film-forming polymer binder and at least one of an inorganic pigment and an organic pigment. 2) 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 polyurea and polyurethane. 3) 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.