JP2002143755A - Coating method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for coating a substrate with a coating material by using an extrusion diehead that can give a coating film having a thickness distribution uniform in the directions of conveyance and width and suffering little from film disturbance or the like due to external factors and has high coating stability. SOLUTION: In a method for coating a substrate supported and continuously conveyed by a backup roll by using a single-layer extrusion diehead, the diehead has a port for feeding a coating material and a pressure gauge. The difference between the measurements of pressures in wait and run states is 1-10 kPa.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating method for applying a coating material to a support which is held by a backup roll and is continuously transported by using an extrusion die head. The present invention also relates to a coating method capable of maintaining a uniform thickness distribution in a transport direction of a coating film and a direction (width direction) orthogonal to the transport direction.

[0002]

2. Description of the Related Art Conventionally, as a method used in a coating apparatus that can be used for photographic light-sensitive materials, an extrusion coating method requires little fluctuation due to evaporation of a coating liquid at the time of coating and mechanical precision is required. It is used because of its excellent film thickness distribution and coating stability. In general, a coating apparatus includes a so-called die head for supplying a coating liquid and a backup roll for uniformly holding the surface of a continuously running support in order to uniformly apply the solution to a body to be coated (hereinafter also referred to as a support). I have.

[0003] Conventionally, as a method of applying a coating solution to a continuously running belt-like support, dip coating, blade coating, air knife coating, wire block coating, gravure coating, reblock coating, reblock coating, and the like. A roll coating method, an extrusion coating method, a slide coating method, a curtain coating method, and an extrusion coating method for a support not held by a backup roll or the like are known. In these coating methods, in order to obtain a uniform dry film thickness in the width direction of the support, special consideration is given to the dimensional accuracy of the coating device and the coating is performed carefully.

[0004] In the above coating method, the extrusion coating method is widely used as a coating method with high accuracy in terms of uniformity of film thickness and smoothness of a coating film surface. The extrusion coating method is a method in which a coating liquid is extruded from a tip end of a slit of a die head and applied while forming beads on a continuously running support.The die head of the extrusion coating method combines two or more blocks, A supply port for supplying the coating liquid, a portion called a manifold for holding the supplied coating liquid in the width direction, and a slit for uniformly discharging the coating liquid from the manifold in the width direction. This is a coating method that enables single-layer to multi-layer coating depending on the number of blocks combined.
Since the coating apparatus for the extrusion coating method has high accuracy, it is necessary to pay close attention to the dimensional accuracy and assembly accuracy of the apparatus. In particular, a high-precision setting is required for the distance between the tip of the die lip for discharging the coating liquid and the support which is the object to be coated, and if the distance is too large, the coating becomes impossible. If it is too small, the entire amount of the coating solution supplied from the die will not be applied, and the film will not flow down to the specified thickness.

The extrusion coating method using the above-mentioned extrusion die head is disclosed in JP-A-56-95363 and JP-A-50-1426.
No. 43, a single layer coating method disclosed in JP-A Nos. 43-12390 and 46-236, and a multi-layer coating method disclosed in JP-A-46-236. Techniques are disclosed. These coating methods are methods in which the extrusion die head is usually applied to a support held by a backup roll while maintaining a clearance of usually 1 mm or less. In addition, various techniques have been known for a coating apparatus and a coating method for making the coating thickness distribution uniform in the width direction. For example, there is a technique related to the design of a die head as represented by Japanese Patent Application Laid-Open No. Hei 8-26679.
This defines the straightness in the width direction of the slit gap of the die head. Conventionally, it has been found that in a pre-metering type coating method such as extrusion coating, the distribution of the coating thickness in the width direction is dominated by the distribution of the discharge flow rate from the die head. For this reason, regarding the design of the die head, a technique for making the slit gap uniform in the width direction as described above, and a technique for preventing and correcting the distortion when the slit gap is distorted due to the influence of the coating liquid pressure or the like. Are known.

[0006] In order to obtain a uniform coating film, a coating method for measuring the coating pressure during coating and managing and controlling the coating pressure so as to fall within a certain range is conventionally known.

For example, JP-A-8-309270 discloses a method of applying a resin solution having a viscosity of 500 cp or more.
It is characterized in that the application pressure of the resin solution to the object is controlled to 350 mmAq or more. However, this method is applicable only in a specific case of applying a resin solution, and it is obvious that stabilizing the paint pressure during application is essential for application stabilization (obviously. ).

Further, such a method for controlling the paint pressure is often applied in a coating method in which a die head is pressed against a free-span support different from the coating method using a backup roll as in the present invention. However, as described above, such a method of controlling only the paint pressure during application has a disadvantage that the paint pressure varies greatly depending on paint physical properties, application conditions, and the like, and thus must be set in accordance with each condition. is there.

In general, there is not much invention relating to the paint pressure during coating in a coating method in which a paint is applied to a support which is held by a backup roll and continuously transported by using an extrusion die head. Furthermore, it is rare in multilayer coating.

The inventors of the present invention provide a coating method in which a coating material is applied to a support held by a backup roll and continuously transported by using an extrusion die head.
Focusing on the paint pressure at the paint die head, and as a result of study, it was found that when there is a certain relationship between the paint pressure in the applied state and the paint pressure in the standby state, it is necessary to suppress the disturbance of the paint film due to external factors. It is possible to improve coating stability and improve coating quality, for example, by maintaining uniform thickness distribution in the transport direction of the coating film and the direction (width direction) perpendicular to the transport direction. That is what I found.

[0011]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to make it possible to maintain a uniform coating thickness distribution in the transport direction and the width direction, and to reduce the disturbance of the coating film due to external factors and to improve the coating stability. It is an object of the present invention to obtain a coating method for applying a paint by using an extrusion die head having a high density.

[0012]

The present invention is achieved by the following means.

1. In a coating method for applying a coating using a single-layer extrusion type die head on a support that is held by a backup roll and continuously transported,
The die head has a paint supply port for introducing the paint and a pressure gauge attached to the supply port, and a difference between pressure measurement values of the pressure gauge in a standby state and a coating state is 1 to 10 kPa. Coating method.

2. In a coating method for applying a coating using a single-layer extrusion type die head on a support that is held by a backup roll and continuously transported,
The die head has a paint supply port for introducing the paint and a pressure gauge attached to the supply port, and a value obtained by dividing a pressure measurement value in an application state by the pressure gauge by a pressure measurement value in a standby state by 1 is obtained. .2 or less.

3. In a coating method for applying a paint to a support held by a backup roll and continuously transported using a two-layer extrusion die head,
The die head has a paint supply port for introducing the upper and lower layer paint and a pressure gauge attached to each supply port, and the difference between the upper layer pressure measurement value in the standby state and the application state is 2 to 15 k.
A coating method, wherein the difference between the measured lower layer pressure in the standby state and the measured value of the lower layer pressure in the coating state is 0.5 to 12 kPa.

4. In a coating method for applying a paint to a support held by a backup roll and continuously transported using a two-layer extrusion die head,
The die head has a paint supply port for introducing upper and lower layer paint and a pressure gauge attached to each supply port, and the value obtained by dividing the upper layer pressure measurement value in the applied state by the upper layer pressure measurement value in the standby state Is 1.3 or less, and a value obtained by dividing the measured value of the lower layer pressure in the coating state by the measured value of the lower layer pressure in the standby state is 1.24 or less.

5. In a coating method for applying paint using a multilayer extrusion die head on a support that is held and continuously transported by a backup roll,
The die head has a plurality of paint supply ports for introducing each layer paint and a plurality of pressure gauges respectively attached to the plurality of paint supply ports, and a pressure measurement value in a standby state and a coating state in each supply port in the application state. A coating method, wherein a difference between a pressure measurement value and a value of an upper layer in an adjacent layer and a value of a lower layer are 10 kPa or less.

Extrusion (extrusion) coating requires relatively high paint viscosity (for example, 0.1 Pa · s to 10 Pa · s).
The paint of s) can be used, and as described above, it is known as a coating method with high accuracy in terms of uniformity of the film thickness and smoothness of the coating film surface.

In the present invention, in an extrusion (extrusion) coating apparatus having a backup roll,
The paint pressure at the paint supply port of the die head (in this case, the pressure applied to the paint at the narrowest point in the path through which the paint passes = the maximum value) is measured.

In the prior art, extrusion is used.
In the applicator, the paint pressure during application is selected as a control (control) factor. The present invention is significantly different from the prior art in that: A) paint is introduced from the supply port at the same flow rate as during application during standby. Then, the measured value (pressure when the die head is separated from the backup roll and drips away) measured from the slit (the pressure measured value in the standby state: A), B) During coating (transporting the support) Then, a pressure measurement value (referred to as B) of the die head is moved to a predetermined position in the vicinity of the backup roll, and the relationship therebetween is defined, thereby keeping the coating thickness distribution in the transport direction and the width direction uniform. The present invention has been found to provide a coating method which can perform coating with high stability and little disturbance of the coating film due to external factors.

Generally, in the extrusion coating, the value of A (that is, the pressure during standby) is 10 kPa to 5 kPa.
About 100 kPa, and these are flow rate, the paint viscosity,
It changes depending on the slit interval of the die head and the like. Accordingly, the B (pressure at the time of application) is generally slightly higher than the value of the A (there is always B ≧ A), so it changes in the range of 10.1 kPa to 100 kPa, These also vary depending on the line speed, the gap between the lip and the support, the angle of the die head, the lip length, and the like. Therefore, in these ranges, appropriate conditions are selected and application is performed depending on what kind of paint is used.

In the present invention, under the conditions for performing such extrusion coating, first, the difference between the pressure measurement value B during coating and the pressure measurement value A in the standby state is defined as a value within a certain range. The feature is to obtain a high quality coating film. That is, in the prior art, only B is used as a control factor, but this greatly changes depending on the application conditions and the paint properties. Therefore, it is necessary to set this in accordance with each application condition and paint physical properties, and it is not a general control factor.

The present invention also differs greatly from the prior art in that B / A is used as a control factor. The value obtained by dividing B by A is a dimensionless value, but by controlling this value to a certain range, it is possible to cope with various application conditions and paint physical properties.

Further, even in the case of two-layer (multilayer) coating, the difference (BA) between the pressure measurement value during application in the upper layer and the pressure measurement value in the standby state, and the pressure measurement value during application in the lower layer and the standby state. The difference (BA) between the pressure measurement values in the state simultaneously satisfies the values in different ranges, and the pressure measurement value during application in the upper layer / the pressure measurement value in the standby state (B / A)
It is necessary that A) and the pressure measurement value during coating / the pressure measurement value B / A in the standby state in the lower layer each satisfy the range of not more than a certain value.

In the multi-layer coating (including two-layer coating), the relationship between adjacent layers can be defined as a characteristic feature of the multi-layer coating. Specifically, A and B measured in each layer can be defined. By defining the difference between the upper layer and the lower layer in a layer where the difference between adjacent layers is within a certain range (upper layer> lower layer), a good coating film can be obtained.

As described above, according to the present invention, not only the pressure during application but also the difference or ratio between the pressure during standby and the pressure during application is selected as a management (control) factor, thereby controlling (control).
There is an advantage that the factors are not largely affected by the paint properties and application conditions.

Therefore, the coating apparatus for carrying out the coating method of the present invention is characterized in that the pressure (= maximum value) applied to the paint at the point where the paint is supplied to the die head at the narrowest point in the passage of the paint at the paint supply port for introducing the paint. Pressure gauge is installed to detect the pressure in the standby state of the die head and the pressure during application, so that the measured pressure value and its difference and ratio are within a specified range. A mechanism that allows the die head to adjust a minute distance near the back roll to change the distance between the support held by the backup roll and the die head lip, or to change the angle of the die head, and an angle changing mechanism It has.

In the present invention, when a paint is applied to a support held by a backup roll and continuously transported by using a single-layer extrusion type die head, a paint supply port for introducing the paint of the die head is provided. The pressure applied to the paint at the point where the paint passes the narrowest (=
The pressure gauge attached to detect the maximum value) makes the difference between the pressure measurement value A in the standby state and the pressure measurement value B in the application state 1 to 10 kPa, thereby improving application stability and suppressing thickness fluctuation. Was found to be effective. That is, if the difference between A and B is too small, coating becomes unstable. Specifically, air may be swirled on the surface of the coating film to cause defects such as coating streaks and liquid breakage. On the other hand, if the difference between A and B is too large, the thickness of the coating film may fluctuate in the transport direction in response to fluctuations in the thickness of the support and fluctuations in tension.

Therefore, it is possible to avoid these problems by keeping the difference between A and B within this range.

Next, it was found that defining the ratio of A and B was effective in suppressing thickness fluctuation in the direction perpendicular to the transport direction. That is, it is effective to set the value of B / A to 1.2 or less. If this ratio is too large, the thickness of the coating film in the direction perpendicular to the transport direction (width direction) may fluctuate sensitively to the fluctuation of the thickness of the support or the fluctuation of the tension as described above. Therefore, when the content is not more than the above value, this problem is less likely to occur, and improvement in coating quality can be expected.

This effect can be applied to each of the upper layer and the lower layer even in the two-layer (multi-layer) coating, and has a paint supply port for introducing the upper and lower layer paints respectively. When applying the paint using a two-layer extrusion die head to which is attached, if the pressure value is read by a pressure gauge attached to a paint supply port for introducing each of the upper and lower paint layers, the upper layer is read. The difference between the pressure measurement value A in the standby state and the pressure measurement value B in the application state is also the pressure measurement value A in the standby state in the lower layer.
And the difference (BA) between the measured upper layer pressure in the standby state and the applied state is 2 to 15 kPa, and the lower layer in the standby state and the applied state. When the difference (BA) between the measured pressure values is 0.5 to 12 kPa, the effect of the present invention is achieved.

In the above two-layer extrusion die head, the value obtained by dividing the measured upper layer pressure in the coated state by the measured upper layer pressure in the standby state is 1.3 or less, and the lower layer pressure in the coated state is less than 1.3. When the value obtained by dividing the pressure measurement value by the lower layer pressure measurement value in the standby state is 1.24 or less, the effect of the present invention is obtained.

Thus, in the two-layer coating, the coating stability of each layer can be improved and the thickness fluctuation can be suppressed.
(However, it has been found that the range of values to be taken is different from the case of single layer coating because the range of values to be taken is two layers.) Further, in the multilayer coating (including two layers coating), each A Research has shown that the difference between B and B affects each other. It is clear that suppressing the difference between the layers can be expected to suppress the thickness fluctuation of each layer due to the mutual influence between the layers. Was.

That is, when a paint is applied using a multilayer extrusion die head, each of the pressure measurement values measured by a pressure gauge attached to each of a plurality of paint supply ports for introducing the paint of each layer of the die head. The difference between the value A in the supply port in the standby state and the value B in the application state is
In an adjacent layer, the difference between the value in the upper layer and the value in the lower layer needs to be 10 kPa or less. Incidentally, this value is “upper layer> lower layer”.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a coating method according to the present invention will be specifically described with reference to the drawings.

FIG. 1 is a schematic sectional view showing a part of an apparatus for performing the coating method of the present invention. The unwinding and winding sections of the support, the drying chamber, and the like are omitted. 1 is a backup roll, 2 is a support, 3 is a single-layer extrusion die head, 4 is a pressure gauge, 5 is a filtration device, 6 is a liquid sending means, 7
Denotes a paint storage tank, and 8 denotes a liquid receiving chamber, in which the received paint is collected or treated as waste liquid. Note that the arrow in the figure indicates the transport direction. Although any pressure gauge may be used as the pressure gauge indicated by 4, a high-precision one is preferably used. FIG. 1 shows a state during coating.

Normally, coating is performed by feeding a predetermined amount of paint to the die head in a state where the three die heads are separated from the one backup roll and waiting (this state is called a standby state). After the cleaning is performed, the support is transported at a predetermined speed, and the coating is applied to the support by moving the die head to a predetermined position near the backup roll (this state is referred to as a coating state).

FIG. 2 is a schematic cross-sectional view of a standby state when a predetermined amount of paint is supplied to the die head during the standby state (standby state).
FIG. 3 is a schematic cross-sectional view of a coated state. The paint pressure measured in FIG. 2 is P, and the pressure measured in FIG.
Then, P ′ ≧ P. As described above, the die head has a small distance change near the back roll between the support held by the backup roll and the die head lip portion, and the die head has a shape such that the difference and the ratio fall within the specified ranges. An adjusting mechanism for changing the angle and an angle changing mechanism are provided.

The slit portion of the die head refers to a narrow gap as shown by 3a in FIG. 3 for uniformly spreading the paint in a direction (width direction) orthogonal to the transport direction. The lip portion of the die head refers to a portion facing the backup roll as shown by 3b in FIG. Normally, the gap value of the slit portion of the die head is designed to be an optimum value according to the paint and the application conditions, but a value between 0.1 mm and 1.5 mm is generally selected. In addition, the length of each lip portion is usually 0.1.
Between 2 mm and 5 mm, but preferably between 0.3 mm and
Between 2 mm. The paint supply port is a portion for introducing paint into a manifold portion inside the die head as shown by 3c in FIG. 3, and is usually provided at one location in the center of the die head in the direction orthogonal to the transport direction. The manifold portion is located between the paint supply port and the slit portion as shown by 3d in FIG. 3 and serves as a buffer.

FIG. 4 shows an example of the case of multi-layer coating.
It is a figure showing an example of a layer extrusion type die head. In this case, the pressure is measured in the same manner as in the case of a single layer. Also in this case, the distance between the support held by the backup roll and the die head lip portion is changed, and the angle of the die head is changed so that the difference and the ratio between P ′ and P in each layer fall within the specified ranges. change. In addition, when the arrow in FIG.
a is a supply port for the upper layer and 4b is a supply port for the lower layer.

Further, suppose that P 'and P in the upper layer of FIG.
Is defined as U, and the difference between P 'and P in the lower layer is defined as L (however, as shown above, P is the pressure measured at the time of standing down and P' is the pressure measured during coating) U> L Becomes As described above, the distance between the backup roll and the die head lip portion is changed or the angle of the die head is changed so that the difference falls within the specified range.

In the coating method according to the present invention,
The coating can be performed under reduced pressure by using the liquid receiving chamber 8 in FIG. 1 as a decompression chamber. Further, the coating method of the present invention can also be applied to coating on a support on which a part of the coating constituent layers has been previously coated.

By performing the coating using such a method, it is possible to increase the stability when applying the coating material, and it is also possible to increase the uniformity of the thickness of the coating film after drying. .

In the present invention, the type of the support used for applying the coating material is not limited, and paper, a plastic film, a metal sheet and the like can be used. Examples of the paper include resin-coated paper and synthetic paper. Examples of the plastic film include a polyolefin film (eg, a polyethylene film, a polypropylene film, etc.), a polyester film (eg, a polyethylene terephthalate film, polyethylene 2,
6-naphthalate film, etc.), polyamide film (eg, polyetherketone film), cellulose acetate film (eg, cellulose triacetate film), and the like. In addition, an aluminum plate is representative of a metal sheet. The thickness of the support used is not particularly limited.

There are no particular restrictions on the paints that can be used in the present invention. For example, paints for photothermographic materials, paints for general and industrial silver halide photosensitive materials, paints for various undercoat layers, and paints for thermosensitive materials Examples thereof include a liquid in which a paint or a polymer material is dissolved in an organic solvent, water, or the like, a pigment dispersion, a colloidal dispersion, and the like.

[0046]

EXAMPLES Hereinafter, the effects of the present invention will be described specifically with reference to examples, but the present invention is not limited to these embodiments.

<< Preparation of Subbed Support >> A commercially available biaxially stretched and heat-fixed support having a width of 500 mm and a thickness of 100 μm and a polyethylene terephthalate (hereinafter abbreviated simply to PET) film of 8 W / m ² · min. Is applied to one surface with the following undercoating coating solution a-1 so as to have a dry film thickness of 0.8 μm, and dried to form an undercoating layer A-1.
On the other side, the following undercoating coating solution b-1 is applied so as to have a dry film thickness of 0.8 μm, and dried to form an undercoating layer B
It was set to -1.

<Undercoating Coating Solution a-1> A copolymer of butyl acrylate (30% by mass), t-butyl acrylate (20% by mass), styrene (25% by mass), and 2-hydroxyethyl acrylate (25% by mass) Combined latex liquid (solid content 30%) 270 g (C-1) 0.6 g Hexamethylene-1,6-bis (ethylene urea) 0.8 g Finished to 1 liter with water.

<Undercoating Coating Solution b-1> 270 g of a copolymer latex liquid (solid content: 30%) of butyl acrylate (40% by weight), styrene (20% by weight), and glycidyl acrylate (40% by weight) 1) 0.6 g Hexamethylene-1,6-bis (ethyleneurea) 0.8 g Make up to 1 liter with water.

Subsequently, the undercoat layer A-1 and the undercoat layer B-1
A corona discharge of 8 W / m ² · min is applied to the upper surface of the lower layer, and a lower layer upper layer coating solution a-2 is applied on the lower layer A-1 so as to have a dry film thickness of 0.1 μm. As the lower pulling upper layer A-2,
On the undercoat layer B-1, an undercoat upper layer coating solution b-2 is applied as an undercoat upper layer B-2 having an antistatic function so as to have a dry film thickness of 0.8 μm. The body was made.

<Coating solution a-2 for lower undercoat> Gelatin 0.4 g / m ² Mass (C-1) 0.2 g (C-2) 0.2 g (C-3) 0.1 g Silica particles ( (Average particle size: 3 μm) 0.1 g Finish to 1 liter with water.

<Lower Coating Upper Layer Coating Solution b-2> (C-4) 60 g Latex liquid containing (C-5) as a component (solid content: 20%) 80 g Ammonium sulfate 0.5 g (C-6) 12 g Polyethylene glycol ( (Weight average molecular weight: 600) 6 g Finished to 1 liter with water.

[0053]

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[0054]

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(Heat Treatment of Support) In the above-mentioned undercoat drying step of the undercoated support, the support was heated at 140 ° C. and then gradually cooled.

(Coating of Back Layer Surface) A back layer paint having the following composition was coated on the above-prepared undercoat layer B-2 using a single-layer extrusion die head (application width: 480 mm) as shown in Table 1. Under the conditions, coating was performed so that the dry film thickness became 3.5 μm. The application was performed at a support traveling speed of 30 m / min, and the drying was performed at 60 ° C. for 5 minutes.

<Coating Solution on Back Side> Cellulose acetate (10% methyl ethyl ketone solution) 15 ml / m ² dye-B 7 mg / m ² dye-C 7 mg / m ² Matting agent: monodispersity 15% average particle size 10 μm monodisperse Silica 30 mg / m ² C ₉ H ₁₇ —C ₆ H ₄ —SO ₃ Na 10 mg / m ²

[0058]

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[0059]

[Table 1]

Each of the conditions in Table 1 was 2000 m
Each coating was performed, and the number of occurrences of a change in the coating thickness in the transport direction and the number of coating breaks or streaks were visually observed. The variation in the thickness of the coating film in the transport direction is a so-called step unevenness, in which the number of those which can be visually confirmed is counted, and the number of times that the coating film is broken or the coating streak is visually observed is counted. According to this, when the value of the applied state pressure measurement value-standby state pressure measurement value (BA) exceeds 10 and is large, a change in coating film thickness occurs in the transport direction. Film breakage or coating streaks occurred. According to the present invention, a good coated product could be obtained without any coating defects.

Further, only the measured pressure in the standby state and the measured pressure in the coating state were changed as shown in Table 2, and the coating was performed under the same other conditions. A sample of the coated product 1000 m after the start of coating was collected, and the film thickness was measured by the following method.

In each sample of the coated product, 100 small pieces were sampled arbitrarily from the entire width of the coating, the small pieces were embedded in methacrylic resin, and the cross section was cut out as a thin piece having a thickness of about 50 μm with a diamond cutter. An image was taken with an electron microscope, the film thickness of the coating layer was actually measured, and the standard deviation (%) of each measured value was evaluated as the coating film thickness variation in the direction perpendicular to the transport direction of each sample.

[0063]

[Table 2]

From Table 2, according to the present invention, it was possible to obtain a good coated product having a coating film thickness variation in the direction perpendicular to the transport direction of 5% or less.

<< Coating of Photosensitive Layer Side and Preparation of Photothermographic Material >> (Preparation of Photosensitive Emulsion) <Preparation of Silver Halide Emulsion> 7.5 g of inert gelatin and 10 mg of potassium bromide were dissolved in 900 ml of water, and the temperature was adjusted. After adjusting the pH to 35 ° C. and 3.0, 74 g of silver nitrate was used.
Of potassium bromide and potassium iodide in a molar ratio of (98/2) with 370 ml of an aqueous solution containing
370 ml of an aqueous solution containing 1 × 10 ^-6 mol of (NO) Cl ₅ ] salt per mol of silver and 1 × 10 ^-4 mol of rhodium chloride salt per mol of silver was obtained by a controlled double jet method while maintaining the pAg at 7.7. Was added. Thereafter, 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added, and the pH was adjusted to 5.0 with NaOH.
Cubic silver iodobromide grains having an average grain size of 0.06 μm, a monodispersity of 10%, a variation coefficient of the projected diameter area of 8%, and a [100] face ratio of 87% were obtained. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant and desalting treatment, and then adjusted to pH 5.9 and pAg 7.5 by adding 0.1 g of phenoxyethanol to obtain a silver halide emulsion. Next, the obtained silver halide emulsion was chemically sensitized with chloroauric acid and inorganic sulfur.

The coefficient of variation of monodispersity and projected diameter area is
It was calculated by the following equation. Monodispersity = (standard deviation of particle size) / (average value of particle size) × 1
00 Coefficient of variation of projected diameter area = (standard deviation of projected diameter area)
/ (Average value of projected diameter area) × 100 <Preparation of Na behenate solution> 32.4 g of behenic acid, 9.9 g of arachidic acid and 5.6 g of stearic acid were dissolved in 945 ml of pure water at 90 ° C. Next, 98 ml of a 1.5 mol / L aqueous sodium hydroxide solution was added while stirring at a high speed. Then, after adding 0.93 ml of concentrated nitric acid, 5
The solution was cooled to 5 ° C. and stirred for 30 minutes to prepare a sodium behenate solution.

<Preparation of Preform Emulsion of Silver Behenate and Silver Halide> 15.1 g of the above silver halide emulsion was added to the above sodium behenate solution, and the pH was adjusted to 8.1 with a sodium hydroxide solution. 147 ml of a 1 mol / L silver nitrate aqueous 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 grains having an average grain size of 0.8 μm and a monodispersity of 8%. After forming the flocs of the dispersion, remove the water,
After performing water washing and water removal six more times, the emulsion was dried to prepare a preform emulsion.

<Preparation of photosensitive emulsion> Polyvinyl butyral (average molecular weight: 30
00) in methyl ethyl ketone (17% by mass) 544
g and 107 g of toluene were gradually added and mixed, and then dispersed with a media disperser at 27.6 MPa to prepare a photosensitive emulsion.

<Preparation of Photosensitive Layer Coating> Photosensitive emulsion 240 g Sensitizing dye-1 (0.1% methanol solution) 1.7 ml Pyridinium bromide perbromide (6% methanol solution) 3 ml Calcium bromide (0.1% 1.7 ml Antifoggant-2 (10% methanol solution) 1.2 ml 2- (4-chlorobenzoyl) benzoic acid (12% methanol solution) 9.2 ml 2-mercaptobenzimidazole (1% methanol solution) 11 ml Tribromomethylsulfoquinoline (5% methanol solution) 17 ml Developer-1 (20% methanol solution) 29.5 ml

[0070]

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<Preparation of Surface Protective Layer Paint> Acetone 35 ml / m ² methyl ethyl ketone 17 ml / m ² cellulose acetate 2.3 g / m ² methanol 7 ml / m ² phthalazine 250 mg / m ² 4-methylphthalic acid 180 mg / m ² tetrachlorophthale Acid 150 mg / m ² Tetrachlorophthalic anhydride 170 mg / m ² Matting agent: Monodispersity 10% Average particle size 4 μm Monodisperse silica 70 mg / m ² C ₉ H ₁₇ —C ₆ H ₄ —SO ₃ Na 10 mg / m ² <Coating method on photosensitive layer side> The above-prepared photosensitive layer paint and surface were coated on the undercoat layer A-2 of a 500 mm wide PET film support coated with the back layer under the coating condition No. 8 in Table 2. The protective layer paint was applied under the conditions shown in Table 3 using an extrusion die head (application width 480 mm) as shown in FIG. , The photosensitive layer coating, the conditions to be 2 g / m ² as silver coverage, also the surface protective layer coating, dry film thickness was coated under the condition to be 2.5 [mu] m. In addition, the running speed of the support was 30 m / min, and the drying was 6
Performed at 0 ° C. for 10 minutes.

[0072]

[Table 3]

Each of the conditions in Table 3 was 2000 m
Each coating was performed, and the number of occurrences of a change in the thickness of the coating film in the transport direction and the number of occurrences of coating film breakage or coating streaks were visually observed. According to this, the value of BA is 12 in the lower layer.
When the upper layer was larger than 15, the thickness of the coating film fluctuated in the transport direction. When the thickness was smaller than 0.5 in the lower layer and smaller than 2 in the upper layer, the coating film was broken or streaked. According to the present invention, a good coated product could be obtained without any coating defects.

Further, only the measured pressure in the standby state and the measured pressure in the coating state were changed as shown in Table 4, and the coating was performed under the same other conditions. A sample of the coated product 1000 m after the start of coating was collected, and the film thickness was measured by the following method.

In each sample of the coated product, 100 small pieces were sampled arbitrarily from the entire width of the coating, the small pieces were embedded in methacrylic resin, and the cross section was cut out as a 200 μm-thick slice with a diamond cutter. Photographs were taken with a microscope, the thickness of the coating layer was actually measured, and the standard deviation (%) of each measured value was evaluated as the coating thickness variation in the direction perpendicular to the transport direction of each sample.

[0076]

[Table 4]

From Table 4, according to the present invention, it was possible to obtain a good coated product in which the variation in the coating thickness in the direction perpendicular to the transport direction was less than 5% for both the upper and lower layers.

Further, only the measured pressure in the standby state and the measured pressure in the coating state were changed as shown in Table 5, and the coating was performed under the same other conditions. A sample of the coated product 1000 m after the start of coating was collected, and the film thickness was measured in the same manner.

[0079]

[Table 5]

From Table 5, it can be seen that according to the present invention, the variation in the coating thickness in the direction perpendicular to the transport direction can be reduced for both the upper and lower layers.

[0081]

EFFECTS OF THE INVENTION An extrusion type in which the disturbance of the coating film due to external factors can be suppressed and the thickness distribution in the transport direction of the coating film and in the direction perpendicular to the transport direction (width direction) can be kept uniform. A coating method using a die head was obtained.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a part of an apparatus for performing a coating method of the present invention.

FIG. 2 is a schematic sectional view of a standby state.

FIG. 3 is a schematic cross-sectional view of a coating state.

FIG. 4 is a diagram showing an example of a two-layer extrusion die head.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 backup roll 2 support 3 single layer extrusion die head 4 pressure gauge 5 filtration device 6 liquid feeding means 7 paint storage tank 8 liquid receiving chamber 3a die head slit 3b die head lip 3c paint supply port 3d manifold 4a upper layer Supply port 4b Supply port for lower layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G03C 1/74 G03C 1/74

Claims (5)

[Claims] 1. A coating method for applying a paint to a support held by a backup roll and continuously transported by using a single-layer extrusion die head, wherein a paint supply port through which the die head introduces the paint is provided. An application method, comprising a pressure gauge attached to a supply port, wherein a difference between a pressure measurement value of the pressure gauge in a standby state and a pressure measurement value of the pressure gauge in an application state is 1 to 10 kPa. 2. A coating method for applying a paint to a support held by a backup roll and continuously transported by using a single-layer extrusion type die head, wherein the die head has a paint supply port for introducing the paint. A coating method comprising: a pressure gauge attached to a supply port, wherein a value obtained by dividing a pressure measurement value in an application state by the pressure gauge by a pressure measurement value in a standby state is 1.2 or less. . 3. A coating method for applying a coating to a support held by a backup roll and continuously transported by using a two-layer extrusion type die head, wherein the die head supplies a coating material for introducing upper and lower layer coatings. With a pressure gauge attached to the port and each supply port, the difference between the upper layer pressure measurement in the standby state and the coating state is 2 to 15 kP
a, wherein the difference between the lower layer pressure measurement values in the standby state and the application state is 0.5 to 12 kPa. 4. A coating method for applying a coating to a support held by a backup roll and continuously transported by using a two-layer extrusion type die head, wherein the die head supplies a coating material for introducing upper and lower layer coatings. Having a pressure gauge attached to the mouth and each supply port, wherein a value obtained by dividing the measured upper layer pressure in the applied state by the measured upper layer pressure in the standby state is 1.3 or less, and A value obtained by dividing the measured lower layer pressure by the measured lower layer pressure in a standby state is 1.24 or less. 5. A coating method for applying a coating to a support held by a backup roll and continuously transported by using a multilayer extrusion die head, wherein the die head supplies a plurality of coatings for introducing each layer coating. A plurality of pressure gauges respectively attached to the mouth and the plurality of paint supply ports, and a difference between a pressure measurement value in a standby state and a pressure measurement value in a coating state in each supply port is higher in an adjacent layer. Wherein the difference between the value of the layer to be formed and the value of the layer to be formed on the lower side is 10 kPa or less.