JP2005227655A - Method for manufacturing heat developable photosensitive material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a heat developable material by which uneven drying is suppressed in a drying step when the heat developable material is manufactured by forming a photosensitive layer and a protective layer through the steps of: simultaneously applying a coating liquid for a photosensitive layer and a coating liquid for a protective layer on a support by a wet-on-wet process; and drying the coating liquids. <P>SOLUTION: In the method for manufacturing a heat developable photosensitive material having a photosensitive layer, on a support, formed by applying a coating liquid for a photosensitive layer containing an organic silver salt, a silver halide, a binder and a reducing agent and a protective layer, on the photosensitive layer, formed by applying a coating liquid for a protective layer, the viscosity of the coating liquid for a protective layer at a shear rate of 1 s<SP>-1</SP>and 25°C is 1.5-5 times that of the coating liquid for a photosensitive layer, and the photosensitive layer and the protective layer are formed through the steps of simultaneously applying the coating liquid for a photosensitive layer and the coating liquid for a protective layer on the support by a wet-on-wet process; and drying the coating liquids. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a photothermographic material, and more particularly, to a method for producing a photothermographic material in which drying unevenness generated in a drying process is suppressed.

  Conventionally, in the medical and printing plate making fields, waste liquids resulting from wet processing of image forming materials have been a problem in terms of workability. In recent years, reduction of waste processing liquids has been strongly desired from the viewpoint of environmental conservation and space saving. It is rare. Therefore, photothermographic materials capable of forming an image only by applying heat have been put into practical use and are rapidly spreading in the above fields.

  Photothermographic materials (hereinafter, also simply referred to as photothermographic materials) have been proposed for a long time. For example, U.S. Pat. Nos. 3,152,904 and 3,457,075; “Dry Silver Photographic Material” by Morgan, D.M. Morgan and B.M. “Thermal Processed SilverSystems” by Shely (Imaging Processes and Materials) Nebelte 8th edition, Sturges, Wall. Walworth), edited by A. Shepp, page 2, 1969) and the like.

  This heat-developable material is processed by a heat-development processing apparatus that forms an image by applying stable heat of 80 to 140 ° C. to a heat-developable material usually called a heat development processor. Since this heat developing material is characterized in that fixing is not performed, the silver halide and organic silver salt remaining in the unexposed portion remain in the heat developing material as they are without being removed. The present invention is directed to such a heat-developable material, and well-known liquid compositions and liquid preparation methods to be applied to the support are used.

  In the production of heat-developable materials, a method is known in which a photosensitive layer and a protective layer formed on the photosensitive layer and a protective layer formed on the photosensitive layer are coated simultaneously with the photosensitive layer in an undried state. No. 15173, US Pat. No. 5,849,363 and the like.

  For example, a slot coater or a slide coater is used for the simultaneous multilayer coating of the heat developing material. In the case of simultaneous multi-layer coating of heat development materials, generally, the coating wet film thickness is relatively thick, so the coating film is disturbed in the drying process, resulting in uneven drying, making it difficult to obtain a uniform coating film. There was a problem that there was.

  As a countermeasure against such unevenness in drying, for example, a fluorinated polymer composed of a fluorinated ethylenically unsaturated monomer and a polar ethylenically unsaturated monomer is included in the binder to reduce madaramura and coating abnormalities on the coating film surface. A technique is known (for example, refer to Patent Document 1). However, in the technique described in Patent Document 1, the physical properties of the surface may change depending on the amount of the fluorinated polymer added, which may cause a problem in the transportability in the subsequent process, and is not always a sufficient measure. Absent.

  Also, in order to minimize the formation of madara that occurs when the coating solvent is evaporated from the coating film coated on the support surface, a drying zone having a plurality of drying subzones is used. At least two drying apparatuses are known which perform drying under different controllable drying conditions, and have no physical barrier for forming a drying subzone (see, for example, Patent Document 2).

  However, in the technique described in Patent Document 2, when the conveyance speed is increased in order to increase productivity, the drying unevenness suppressing effect may not always be sufficient, and the photothermographic material according to the present invention is sufficiently compatible. is not.

  Also known is a method for producing a photothermographic material having an optimum coated surface by defining the viscosity of a coating solution for an image forming layer and a coating solution for a protective layer using polymer latex as a binder ( For example, see Patent Document 3.)

  However, the technique described in Patent Document 3 is a technique when a polymer latex is used as the binder, and when a material other than the polymer latex is used as the binder, it is not always a sufficient measure for preventing drying unevenness.

From such a situation, the photosensitive layer coating solution and the protective layer coating solution are applied simultaneously on the support, and the photothermographic layer and the protective layer are formed through a drying process. Development of a method for producing a heat-developable material that suppresses drying unevenness that occurs in the process is desired.
Japanese Patent Laid-Open No. 9-5925 Special table 2000-508050 gazette JP 2001-75228 A

  The present invention has been made in view of the above circumstances, and its purpose is to simultaneously apply a coating solution for a photosensitive layer and a coating solution for a protective layer on a support, and form a photosensitive layer and a protective layer through a drying step. Another object of the present invention is to provide a method for producing a heat-developable material that suppresses drying unevenness that occurs in the drying step of the heat-developable material produced.

  The object of the present invention has been achieved by the following constitution.

(Claim 1)
A photosensitive layer formed by coating a coating solution for a photosensitive layer containing organic silver, silver halide, a binder and a reducing agent on a support, and a coating solution for a protective layer is formed on the photosensitive layer. In the method for producing a photothermographic material having a protected layer,
The viscosity of the protective layer coating solution at a shear rate of 1 sec ⁻¹ and 25 ° C. is 1.5 to 5 times the viscosity of the photosensitive layer coating solution,
The photothermographic material, wherein the photosensitive layer and the protective layer are formed through a step of simultaneously applying the photosensitive layer coating solution and the protective layer coating solution on the support and drying them. Manufacturing method.

(Claim 2)
The viscosity of the protective layer coating liquid shear rate 1 sec ^-1, at 25 ° C., at 1.0~5.0Pa · sec, and the viscosity of the photosensitive layer coating liquid shear rate 1 sec ^-1, at 25 ° C., The method for producing a photothermographic material according to claim 1, wherein the production method is 0.2 to 1.0 Pa · sec.

(Claim 3)
A photosensitive layer formed by coating a coating solution for a photosensitive layer containing organic silver, silver halide, a binder and a reducing agent on a support, and a coating solution for a protective layer is formed on the photosensitive layer. In the method for producing a photothermographic material having a protected layer,
The photosensitive layer and the protective layer are formed through a step of simultaneously applying the photosensitive layer coating solution and the protective layer coating solution on the support, and a drying step after coating,
From the start of drying in the drying step until the amount of solvent in the coating film is reduced to 2/3 of the amount of solvent in the coating film immediately after coating, the average evaporation rate of the solvent is 0.2-2 g / m ² · A method for producing a photothermographic material, characterized in that it is sec.

(Claim 4)
4. The photothermographic material according to claim 3, wherein the drying step has an average evaporation rate of 0.5 to 3 g / m ² · sec from the start of drying to a point at which touch drying is possible. Method.

(Claim 5)
5. The heat according to claim 3, wherein the protective layer coating solution has a viscosity of 1.5 to 5 times the viscosity of the photosensitive layer coating solution at a shear rate of 1 sec ⁻¹ and 25 ° C. 6. A method for producing a development photosensitive material.

(Claim 6)
The viscosity of the photosensitive layer coating solution is 0.2 to 1.0 Pa · sec at a shear rate of 1 sec ⁻¹ and 25 ° C., and the viscosity of the protective layer coating solution is a shear rate of 1 sec ⁻¹ and 25 ° C. The method for producing a photothermographic material according to claim 5, wherein the production method is 1.0 to 5.0 Pa · sec.

  As a result of diligent studies to achieve the above-mentioned problems, the inventors formed a photosensitive layer and a protective layer by simultaneously applying a coating solution for a photosensitive layer and a coating solution for a protective layer on a support and drying them. When producing a heat developing material, it was found that drying unevenness generated in the drying process is more likely to occur in the heat developing material than in a general silver halide photographic light sensitive material produced by simultaneous multilayer coating.

  The following items were estimated as the main cause of unevenness in drying. 1) After coating each coating film for forming the photosensitive layer and the protective layer on the support, each coating film for forming the photosensitive layer and the protective layer transported to the drying process has a solvent. Since it is layered in a state of being included, when the drying air is blown on the coating film surface forming the protective layer in the drying process, the coating film surface moves and unevenness in the thickness of the coating film can occur. Uneven drying occurs. 2) By rapidly evaporating the solvent of the coating solution, the coating film is disturbed, resulting in unevenness and drying unevenness.

  In order to prevent the occurrence of uneven drying, 1) the coating film for forming the protective layer coated on the coating film for forming the photosensitive layer has physical properties that are difficult to move even when blown with dry air. ) It has been found that it is effective to prevent the solvent from evaporating at a time from the start of drying until the coating film stops moving, and as soon as the present invention has been achieved.

  Drying unevenness generated in the drying process of the photothermographic material produced by simultaneously coating the photosensitive layer coating liquid and the protective layer coating liquid on the support and forming the photosensitive layer and the protective layer through the drying process. A method for producing a photothermographic material with reduced heat resistance can be provided, failure of the coating film surface is eliminated, and stable production is possible with a high yield rate.

  An embodiment according to the present invention will be described with reference to FIG. 1, but the present invention is not limited to this.

  FIG. 1 is a schematic view showing an example of a method for producing a heat-developable material including steps from coating to drying.

  In the figure, reference numeral 1 denotes a simultaneous multi-layer coater that is held by a back roll 2 and simultaneously applies a photosensitive layer coating solution for forming a photosensitive layer and a protective layer coating solution for forming a protective layer on a belt-like support 3 that is continuously conveyed. Indicates. The simultaneous multi-layer coater is not particularly limited, and examples thereof include known coaters such as curtain coaters, slot coaters, and slide coaters. Among these coaters, preferred coaters include a slide coater and a slot coater. This figure shows the case where a slide coater for three-layer simultaneous multilayering is used. Japanese Patent Laid-Open No. 2000-15173 has a detailed description of a simultaneous multilayer coating method using a simultaneous multilayer coater.

  Reference numerals 4a to 4c denote support rolls that support the conveyance (the conveyance direction is an arrow direction in the drawing) of the belt-like support 3a having a coating film that forms a photosensitive layer and a coating film that forms a protective layer. Reference numeral 5 denotes a drying apparatus for drying the belt-like support 3a having a coating film for forming a photosensitive layer and a coating film for forming a protective layer. The drying device 5 may be either an air mode drying type drying device that dries with heated air or an inert drying type drying device that dries with a heated inert gas. The drying device 5 has a drying zone in which drying boxes 501a and 501b that can individually control the drying conditions are continuously connected. More specifically, the area between the inlet 502 of the drying box 501a and the outlet 503 of the drying box 501b of the belt-like support 3a having the coating film for forming the photosensitive layer and the coating film for forming the protective layer is called a drying zone. Furthermore, in the present invention, the area from the inlet 502 of the drying box 501a to the outlet of the drying box 501a is referred to as a first drying zone, and the area from the inlet of the drying box 501b to the outlet 503 is referred to as a second drying zone.

  The number of drying boxes is not particularly limited, and can be appropriately changed depending on the coating film thickness of the belt-like support 3a having the coating film to be dried, the conveyance speed, the drying temperature, the amount of drying air, and the like. This figure shows the case where there are two drying boxes. Also, the length of the drying box may be different. In the case of this figure, the case where the drying box 501b is longer than the drying box 501a (the 2nd drying zone is longer than the 1st drying zone) is shown.

  Reference numerals 504a and 504b denote hot air supply headers which are hot air supply means for supplying hot air to the respective drying boxes 501a and 501b.

  Reference numerals 505a and 505b denote hot air exhaust ports disposed in the respective drying boxes 501a and 501b. Reference numerals 506a and 506b denote hot air supply ports provided in the hot air supply headers 504a and 504b. Reference numerals 507a and 507b denote hot air outlets provided in the hot air supply headers 504a and 504b. Reference numerals 508a and 508b denote control boxes for hot air sent from the hot air supply pipe 6, which have a heater and a cooler. Reference numerals 509a and 509b denote filters. Reference numerals 510a and 510b denote hot air supply fans that send hot air to the hot air supply headers 504a and 504b, and reference numerals 511a and 511b denote exhaust fans.

  The temperature of the warm air sent from the warm air supply pipe 6 by each warm air supply fan 510a, 510b is adjusted by each control box, dust is removed by each filter 509a, 509b, and each warm air supply header 504a, 504b. The supplied hot air is sprayed from the hot air blowing ports 507a and 507b onto the belt-like support 3a having the coating film, and the coating film is dried. 511b exhausts the drying apparatus 5 through the exhaust pipe 7.

  The hot air outlets 507a and 507b are formed by a punching plate or a slit nozzle in order to blow out substantially uniform drying air in the width direction. As the warm air supplied from the outlets 507a and 507b to the surface of the coating film, it is possible to appropriately select and use warm air heated from room temperature to about 120 degrees depending on the type of the coating film.

  Reference numeral 8 denotes a coating liquid supply unit. Reference numeral 801 denotes a tank of a coating auxiliary coating solution used in the lowermost layer in order to stabilize the coating, and the coating auxiliary coating solution in the tank is sent to the coater 1 through a liquid feeding pipe 801b by a liquid feeding pump 801a. Reference numeral 802 denotes a tank for the photosensitive layer coating solution. The photosensitive layer coating solution in the tank is sent to the coater 1 by the liquid feed pump 802a via the liquid feed pipe 802b. Reference numeral 803 denotes a tank for the protective layer coating liquid, and the protective layer coating liquid in the tank is sent to the coater 1 by the liquid feed pump 803a via the liquid feed pipe 803b.

  Each coating solution sent to the coater 1 has the coating auxiliary coating solution as the lowermost layer, the photosensitive layer coating solution is placed on the coating auxiliary coating solution, and the protective layer coating solution is placed on the photosensitive layer coating solution. In this state, the slide surface 101 flows down and is applied onto the belt-like support, and the solvent evaporates and dries by the drying device 5 to form a photosensitive layer and a protective layer on the belt-like support. Reference numeral 9 denotes a roll-shaped heat development material obtained by winding a heat-development material having been dried and having a photosensitive layer and a protective layer formed on a belt-like support in a roll shape around a core 901.

  In the drying zone, after applying the photosensitive layer coating solution and the protective layer coating solution, warm air controlled to a set temperature is sent to the drying chamber to evaporate the solvent in the coating film and dry the coating film. At this time, the coating film surface is disturbed by the warm air, causing a phenomenon of uneven thickness of the coated film, which may cause uneven drying. Although the drying unevenness is in the direction of suppression by weakening this warm air, the weaker it is, the slower the drying becomes, and it becomes necessary to lengthen the processing time of the drying zone. In this case, the drying zone is required to be long, resulting in an increase in equipment cost, and a problem that the productivity is lowered by reducing the conveyance speed. In particular, fine film thickness unevenness that does not normally cause a problem in a photothermographic material is often manifested by development, and the required accuracy for coating film uniformity is extremely high.

  The method for producing a photothermographic material of the present invention is a method for suppressing drying unevenness due to warm air, and will be described below with specific means.

The viscosity of the protective layer coating solution according to the present invention is 1.5 to 5 times the viscosity of the photosensitive layer coating solution at a shear rate of 1 sec ⁻¹ and 25 ° C. If it is less than 1.5 times, when the coating solution for the protective layer is applied, the coating film is easy to flow, and it is not possible to obtain sufficient protection against disturbances such as spraying of dry air and vibration accompanying conveyance. Unevenness is likely to occur on the surface, which is not preferable. In the case of exceeding 5 times, the photosensitive layer is easy to move against disturbances such as spraying of dry air and vibration accompanying conveyance, and the photosensitive layer does not become a uniform coated surface, which is not preferable.

  That is, the method for producing a photothermographic material of the present invention makes it difficult to be affected by disturbance by performing simultaneous multi-layer coating with a balance in which the viscosity of the coating solution for the protective layer is higher than the viscosity of the coating solution for the photosensitive layer. It is characterized by prevention.

The viscosity of the photosensitive layer coating solution according to the present invention is preferably 0.2 to 1.0 Pa · sec at a shear rate of 1 sec ⁻¹ and 25 ° C. If it is less than 0.2 Pa · sec, depending on the type of the coating solution for the photosensitive layer, sedimentation of the dispersed particles in the coating solution for the photosensitive layer may occur, and stable coating may not be possible. When exceeding 1.0 Pa · sec, depending on the type of the coating solution for the photosensitive layer, streak defects or the like are likely to occur during coating, and the coating property may be impaired.

The viscosity of the protective layer coating solution according to the present invention is preferably 1.0 to 5.0 Pa · sec at a shear rate of 1 sec ⁻¹ and 25 ° C. If it is less than 1.0 Pa · sec, depending on the type of the coating liquid for the protective layer, when the coating liquid for the protective layer is applied, the coating film tends to flow, and is susceptible to disturbances such as blowing dry air, Drying unevenness may occur. When the pressure exceeds 5.0 Pa · sec, the pressure loss during feeding of the coating liquid for the protective layer becomes large, and equipment such as pressure-resistant liquid feeding equipment is required, and the equipment may be too expensive.

  In addition, a viscosity shows the value measured using the Rheometrics Far East Co., Ltd. RFS fluid spectrometer.

In the method for producing a heat developing material of the present invention, the viscosity of the protective layer coating solution is 1.5 to 5 times higher than the viscosity of the photosensitive layer coating solution, more preferably the viscosity of the protective layer coating solution is the shear rate. 1 sec ^-1, at 1.0~5.0Pa · sec at 25 ° C., and the photosensitive layer coating solution viscosity shear rate 1 sec ^-1 of, by the 0.2~1.0Pa · sec at 25 ° C. The following effects can be obtained.

  By making the viscosity of the coating solution for the protective layer to which the hot air is directly sprayed higher than the viscosity of the coating solution for the photosensitive layer, the coating layer does not impair the coating properties such as coating muscle failure, and the protective layer is caused by disturbance such as the blowing of warm air. By preventing the disturbance of the coating film forming the film, the coating film forming the lower photosensitive layer is prevented from being disturbed and can be uniformly dried.

  Furthermore, in the drying zone, hot air is blown onto the multilayer coating film in which the coating film for forming the photosensitive layer and the coating film for forming the protective layer are blown, whereby the solvent in the coating film evaporates, and the photosensitive layer and the protective layer are protected. A layer is formed. Even at this stage, each coating film is disturbed by the evaporation speed of the solvent from each coating film, which is one of the causes of drying unevenness. In particular, at the stage of starting drying, the coating film contains a large amount of solvent, so that it is easy to flow. If the solvent is suddenly evaporated at this stage, each coating film is disturbed and drying unevenness is likely to occur. For this reason, it is sufficient to evaporate the solvent gently in order to prevent drying unevenness. However, the milder the drying, the longer the drying time, and the longer the processing time of the drying zone becomes. In that case, it becomes necessary to lengthen the drying zone, resulting in an increase in equipment cost or a decrease in productivity by reducing the conveyance speed.

  The method for producing the heat-developable material of the present invention is a method for suppressing drying unevenness due to evaporation of the solvent from the coating film, and will be described below with specific means. Normally, the drying zone has a structure in which a plurality of drying chambers are connected in series as shown in FIG. 1, and it is possible to set a hot air supply amount and a temperature condition for each drying chamber.

As a means relating to the evaporation of the solvent in the method for producing the heat-developable material of the present invention, the solvent evaporation rate is particularly slowed at the drying start stage, which contains a large amount of solvent, and the coating film is easy to flow and weak in disturbance resistance. Unevenness of drying can also be suppressed by increasing the evaporation rate of the solvent from the initial stage at the stage where the evaporation film is difficult to flow and the resistance to disturbance becomes strong. Specifically, in the drying zone, from the start of drying until the amount of solvent in the coating film is reduced to 2/3 of the amount of solvent in the coating film immediately after coating, the solvent evaporation rate is 0.2-2 g / This is a method of m ² · sec.

If it is less than 0.2 g / m ² · sec, it is effective in preventing drying unevenness, but by reducing the transport speed and performing drying, it is necessary to reduce production efficiency or lengthen the drying zone, resulting in equipment costs. Increase, which is not preferable.

If it exceeds ² g / m ² · sec, the coating film is disturbed due to evaporation of the solvent, and drying unevenness occurs, which is not preferable.

  By preventing the turbulence of the coating film accompanying the evaporation of the solvent at the start of drying by slowing the evaporation rate of the solvent at this stage, which contains a large amount of solvent and the coating film flows easily and the disturbance resistance is weak. It has become possible to prevent the occurrence of drying unevenness.

As another preferred means relating to the evaporation of the solvent in the method for producing the heat-developable material of the present invention, the solvent evaporation rate is particularly slowed at the drying start stage, which contains a large amount of the solvent and the coating film is easy to flow and the disturbance resistance is weak, It is also possible to increase the evaporation rate of the solvent at a stage where the solvent evaporates to some extent and the coating film does not flow easily and resistance to disturbance becomes strong. Specifically, during the drying process, the average evaporation rate of the solvent is 0.2 to 2 g from the start of drying until the solvent amount in the coating film is reduced to 2/3 of the solvent amount in the coating film immediately after coating. / m and ² · sec, the average evaporation rate of the solvent to dry tack can point from the start of drying it is preferable to 0.5 to 3 g / m ² · sec. If the average evaporation rate of the solvent up to the touchable point is less than 0.5 g / m ² · sec, it is effective in preventing drying unevenness, but the production efficiency is reduced by reducing the transport speed and drying. Or it may be necessary to lengthen the drying zone, resulting in an increase in equipment costs. When the average evaporation rate of the solvent up to the point at which the touch can be dried exceeds 3 g / m ² · sec, the coating film may be disturbed due to evaporation of the solvent, and drying unevenness may occur.

  The finger-dryable point is a point at which the solvent in the coating film evaporates to some extent and can be contacted with a finger, and changes depending on the type of coating film, the content of the solvent, and the thickness of the coating film.

  By prescribing the evaporation rate of the solvent from the start of drying to the point at which touch drying is possible within the above range, it becomes possible to prevent uneven drying due to the disturbance of the coating layer accompanying the evaporation of the solvent from the coating film. However, it became possible to produce a more stable heat developing material.

  In this way, it contains a lot of solvent, the coating film is easy to flow, and the resistance to disturbance is weak. This prevents the coating film from being disturbed due to evaporation of the solvent especially at the start of drying, and prevents the coating film from being disturbed due to evaporation of the solvent throughout the drying process. It became possible to prevent the occurrence of unevenness.

  Note that the evaporation rate of the drying process can be performed according to an estimation method according to “MODERN COATING AND DRYING TECHNOLOGY” by Edward Cohen and Edgar Gutoff, for example. The evaporation rate of each drying chamber can also be measured by sealing the wet coating film at the inlet and outlet of each drying chamber in the drying zone and sampling to change the weight.

  The photothermographic material according to the invention is not particularly limited in the coating solution used for the photosensitive layer and the non-photosensitive protective layer. For example, JP-A Nos. 2003-156814, 2003-156913, 2003-140292, 2003-131343, 2003-131335, 2003-098627, 2003-098622, 2003-029371, 2002-296732, 2002-268178, 2002-040593 Things.

  Hereinafter, although an example is given and the concrete effect of the present invention is shown, the mode of the present invention is not limited to this.

Example 1
According to the method shown below, a coating solution for a photosensitive layer and a coating solution for a protective layer containing an organic silver component were prepared.

<Coating solution for photosensitive layer>
<< Preparation of silver halide emulsion A >>
After dissolving 7.5 kg of inert gelatin and 10 g of potassium bromide in 900 L of water to adjust the temperature to 35 ° C. and pH to 3.0, bromide with a molar ratio of (98/2) to 370 L of an aqueous solution containing 74 kg of silver nitrate 370 L of an aqueous solution containing 1 × 10 ⁻⁶ mol of potassium, potassium iodide and [Ir (NO) Cl ₅ ] salt per mol of silver and 1 × 10 ⁻⁶ mol of rhodium chloride per mol of silver was added to pAg 7.7. Added by the controlled double jet method. Thereafter, 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added, the pH was adjusted to 5 with NaOH, the average particle size was 0.06 μm, the monodispersity was 10%, the projected diameter An emulsion containing cubic silver iodobromide grains having an area variation coefficient of 8% and a [100] face ratio of 87% was obtained. The emulsion was coagulated and precipitated using a gelatin flocculant and desalted, and then 100 g of phenoxyethanol was added to adjust the pH to 5.9 and pAg of 7.5 to obtain a silver halide emulsion. Further, the obtained silver halide emulsion was chemically sensitized with chloroauric acid and inorganic sulfur to obtain silver halide emulsion A.

  The coefficient of variation of the monodispersity and the projected diameter area was calculated by the following equation.

Monodispersity (%) = (standard deviation of particle size) / (average value of particle size) × 100
Variation coefficient of projected diameter area (%) = (standard deviation of projected diameter area) / (average value of projected diameter area) × 100
<< Preparation of Na behenate solution >>
In 945 L of pure water, 32.4 kg of behenic acid, 9.9 kg of arachidic acid, and 5.6 kg of stearic acid were dissolved at 90 ° C. Next, 98 L of a 1.5 mol / L sodium hydroxide aqueous solution was added while stirring at high speed. Next, 0.93 L of concentrated nitric acid was added, and the mixture was cooled to 55 ° C. and stirred for 30 minutes to obtain a sodium behenate solution.
(Preform emulsion preparation)
15.1 kg of the above silver halide emulsion A was added to the above sodium behenate solution, and the pH was adjusted to 8.1 with a sodium hydroxide solution. Then, 147 L of a 1 mol / L silver nitrate solution was added over 7 minutes, and the mixture was further stirred for 20 minutes. Water-soluble salts were removed by ultrafiltration. The resulting silver behenate was a grain having an average grain size of 0.8 μm and a monodispersity of 8%. After forming the floc of the dispersion, water was removed, water was washed 6 times, water was removed and dried, and then 544 kg of a methyl ethyl ketone solution (17% by mass) of polyvinyl butyral (average molecular weight 3000) and 107 kg of toluene. Was gradually added and mixed, and then dispersed at 27.6 MPa with a media disperser to prepare a preform emulsion.

<Preparation of coating solution for photosensitive layer>
Using the above-described preform emulsion, photosensitive layer coating solutions having different viscosities as shown in Table 1 were prepared according to the formulations shown below and designated as AD. The viscosity value was a value at 25 ° C. with a shear rate of 1 sec ⁻¹ , and the change in viscosity was adjusted by the amount of methyl ethyl ketone when the photosensitive layer coating solution was prepared. The viscosity was measured using an RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd.

(Prescription of coating solution for photosensitive layer)
Preform emulsion 240kg
Sensitizing dye-1 (0.1% methanol solution) 1.7 L
Pyridinium Promide Perbromide (6% methanol solution) 3L
Calcium bromide (0.1% methanol solution) 1.7L
Antifoggant-1 (10% methanol solution) 1.2L
2- (4-Chlorobenzoylbenzoic acid (12% methanol solution))
9.2L
2-mercaptobenzimidazole (1% methanol solution) 11L
Tribromomethylsulfoquinoline (5% methanol solution) 17L
Developer-1 (20% methanol solution) 29.5L

<Preparation of coating solution for protective layer>
As shown in Table 2, coating solutions for protective layers having different viscosities were prepared according to the formulations shown below and designated as a to i. The viscosity value was a value at a shear rate of 1 sec ⁻¹ and 25 ° C., and the change in viscosity was adjusted by the amount of methyl ethyl ketone. The viscosity was measured using an RFS fluid spectrometer manufactured by Rheometrics Far East Co., Ltd.

(Preparation of coating solution for protective layer)
Methyl ethyl ketone 52L
Cellulose acetate 2.3kg
Methanol 7L
Phthalazine 250g
4-methylphthalic acid 180g
150 g of tetrachlorophthalic acid
170 g of tetrachlorophthalic anhydride
Matting agent: 10% monodispersion average particle size 4 μm monodispersed silica
70g
_{C 9 H 19 -C 6 H 4} -SO 3 Na 10g
The preparation amount of the coating solution for the photosensitive layer and the coating solution for the non-photosensitive protective layer was prepared according to the coating amount, with the above-mentioned preparation amount as one unit.

<Coating / Drying>
Table 3 shows the coating solution for the photosensitive layer and the coating solution for the protective layer prepared in order on the support using a polyethylene terephthalate support having a width of 500 mm, a thickness of 175 μm, and a length of 100 m using the coating and drying apparatus shown in FIG. As shown, heat-developable materials were prepared by simultaneous multi-layer application using a slide coater for simultaneous application of three layers under the conditions of an application speed of 20 m / min and an application width of 460 mm. In addition, when performing simultaneous multilayer coating, the coating auxiliary coating solution was simultaneously coated on the lowermost layer. The drying apparatus has a first drying zone of 10 m and a second drying zone of 20 m, and has a total length of 30 m. The air is blown from the slit nozzle in the drying apparatus, the nozzle pressure in both zones is 50 Pa, the temperature of the drying air is 70 ° C., and the average evaporation rate of the solvent is about 4.0 g / m ^{2 in} all zones.・ It was sec. The supply flow rate of each coating solution was adjusted so that the photosensitive layer had a dry coating amount of 18 g / m ² and the protective layer had a dry coating amount of 2 g / m ² .

(Preparation of coating auxiliary coating solution)
VITEL PE2200 (polyester manufactured by Shell) 0.3% by mass
BL-5Z (polyvinyl butyral manufactured by Sekisui Chemical Co., Ltd.) 10.0% by mass
(Evaluation)
Table 3 shows the results obtained by visually observing streak defects and drying unevenness on the coating surface from the start of application to the end of application on the obtained samples 101 to 111 and evaluating with the following evaluation ranks.
Evaluation rank of streak defects on coating surface ○: Almost no streak defects and commercialization level ○ △: Scratch defects are confirmed to be extremely weak, but commercialization tolerance level △: Streaks defects are confirmed to be weak, but commercialization tolerance level △ ×: Level of streak defect confirmed slightly strong and impossible to make a product ×: Level of streak defect strongly confirmed and impossible to make a product Evaluation rank of dry unevenness on coating surface ○: Almost dry unevenness Product level ○ △: Drying unevenness is confirmed to be extremely weak, but commercialization acceptable level △: Drying unevenness is confirmed to be weak, but commercialization acceptable level Δ ×: Drying unevenness is confirmed to be slightly strong, resulting in a product Unacceptable level ×: Level at which drying unevenness is strongly confirmed and cannot be made into a product

  The effectiveness of the present invention was confirmed.

Example 2
When the sample 105 of Example 1 was produced, the amount of solvent in the coating film in the first drying zone was reduced to 2/3 of the amount of solvent in the coating film immediately after coating (1 of the total amount of solvent immediately after coating). As shown in Table 4, the average evaporation rate up to the touch-drying point in the entire drying process in which the coating speed and the drying conditions were changed so that / 3 was evaporated) and the drying conditions in the second drying zone were changed. Except for the above, heat-developable materials were produced in the same manner as in Example 1, and Samples 201 to 207 were obtained. The average evaporation rate of the solvent in the first and second drying zones was adjusted by the temperature of the drying air and the blowing nozzle pressure of the drying air.

(Evaluation)
Regarding the obtained samples 201 to 207, the drying unevenness of the coating film surface was visually observed in the same manner as in Example 1 from the start of application to the end of application, and the results of evaluation with the same evaluation rank as in Example 1 are shown in Table 4. .

  The effectiveness of the present invention was confirmed.

It is the schematic which shows an example of the manufacturing method of the heat developable material including a drying process from application | coating.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coat for simultaneous multi-layers 3 Band-shaped support body 5 Drying apparatus 501a, 501b Drying box 502 Inlet 503 Outlet 504a, 504b Hot air supply header 505a, 505b Exhaust port 506a, 506b Hot air supply port 507a, 507b Hot air outlet port 508a50 Control box 6 Hot air supply pipe 7 Exhaust pipe 8 Coating liquid supply section 801, 802, 803 Tank 9 Roll-shaped heat developing material

Claims (6)

A photosensitive layer formed by coating a coating solution for a photosensitive layer containing organic silver, silver halide, a binder and a reducing agent on a support, and a coating solution for a protective layer is formed on the photosensitive layer. In the method for producing a photothermographic material having a protected layer,
The viscosity of the protective layer coating solution at a shear rate of 1 sec ⁻¹ and 25 ° C. is 1.5 to 5 times the viscosity of the photosensitive layer coating solution,
The photothermographic material, wherein the photosensitive layer and the protective layer are formed through a step of simultaneously applying the photosensitive layer coating solution and the protective layer coating solution on the support and drying them. Manufacturing method. The viscosity of the protective layer coating liquid shear rate 1 sec ^-1, at 25 ° C., at 1.0~5.0Pa · sec, and the viscosity of the photosensitive layer coating liquid shear rate 1 sec ^-1, at 25 ° C., The method for producing a photothermographic material according to claim 1, wherein the production method is 0.2 to 1.0 Pa · sec. A photosensitive layer formed by coating a coating solution for a photosensitive layer containing organic silver, silver halide, a binder and a reducing agent on a support, and a coating solution for a protective layer is formed on the photosensitive layer. In the method for producing a photothermographic material having a protected layer,
The photosensitive layer and the protective layer are formed through a step of simultaneously applying the photosensitive layer coating solution and the protective layer coating solution on the support, and a drying step after coating,
From the start of drying in the drying step until the amount of solvent in the coating film is reduced to 2/3 of the amount of solvent in the coating film immediately after coating, the average evaporation rate of the solvent is 0.2-2 g / m ² · A method for producing a photothermographic material, characterized in that it is sec. 4. The photothermographic material according to claim 3, wherein the drying step has an average evaporation rate of 0.5 to 3 g / m ² · sec from the start of drying to a point at which touch drying is possible. Method. 5. The heat according to claim 3, wherein the protective layer coating solution has a viscosity of 1.5 to 5 times the viscosity of the photosensitive layer coating solution at a shear rate of 1 sec ⁻¹ and 25 ° C. 6. A method for producing a development photosensitive material. The viscosity of the photosensitive layer coating solution is 0.2 to 1.0 Pa · sec at a shear rate of 1 sec ⁻¹ and 25 ° C., and the viscosity of the protective layer coating solution is a shear rate of 1 sec ⁻¹ and 25 ° C. The method for producing a photothermographic material according to claim 5, wherein the production method is 1.0 to 5.0 Pa · sec.

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