JP2003280144A - Method for manufacturing base for photography, and the base for photography - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a base for photography which can apply gelatine undercoat layer coating liquid at a high speed to the base for continuously traveling photography and is free of coating unevenness, a defect in coating of an undercoat layer due to formation of an air bubble, and breaking of paper at a coater part. <P>SOLUTION: In the method for manufacturing the base 1 for photography, in which a resin coating layer containing mainly polyolefin resin is formed on both the surfaces of a sheet type base body and the gelatine coating liquid 7 is applied on the resin coating layer on the side where a photographic emulsion should be applied by an offset gravure coater to form the undercoat layer, an offset roll 4 is reversed in the rotating direction of a backup roll 2 as the traveling direction of the base and a gravure roll 5 is reversed in the rotating direction of the offset roll; and the offset roll and backup roll face each other at an interval larger than the thickness of the base and the backup roll to perform coating by a kiss reverse coating system wherein the offset roll abuts against the base on the backup roll. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a photographic support and a photographic support. To further explain,
The present invention is a method for producing a photographic support, which enables high-speed coating of a gelatin subbing layer coating liquid on a continuously running photographic support without uneven coating and a uniform undercoat layer profile. Further, there is no coating defect of the undercoat layer due to generation of bubbles, there is no paper break in the coater section, a method for producing a photographic support excellent in quality and operation, and a photographic support. is there.

[0002]

2. Description of the Related Art In recent years, a water-resistant photographic support obtained by coating both sides of a paper base with a polyolefin resin has been widely used as a photographic support. In such a water-resistant photographic support, since the polyolefin resin coating layer is hydrophobic, it is difficult for the processing liquid to permeate into the paper base portion in the photographic support during the developing and fixing process. In order to
Washing time and drying time are shortened, and since the processing liquid does not penetrate into the paper substrate, expansion and contraction of the photographic support is suppressed,
It has advantages such as improved dimensional stability.

However, in these water-resistant photographic supports, since the surface formed by the polyolefin resin coating layer is hydrophobic, a photographic emulsion layer containing highly hydrophilic gelatin as a binder is formed thereon. It is difficult to adhere firmly. Then, the surface of the hydrophobic polyolefin resin coating layer is activated by corona discharge treatment, flame treatment, chemical treatment, etc. to improve its adhesiveness, and then a photographic emulsion is applied to it. It was

However, the method of activating the polyolefin resin-coated surface as described above sometimes causes problems such as fog on the photographic emulsion.
Furthermore, even if the surface activation treatment is performed, there is a phenomenon that the activity of the obtained polyolefin resin coating layer surface decreases with time, so that when the photographic emulsion layer is coated after a long time has passed since the activation treatment, In some cases, the wettability and the adhesiveness to the emulsion became poor, and a product failure occurred in which the photographic emulsion layer was peeled off from the surface of the polyolefin resin coating layer during the development process.

In order to solve the above problems, in recent years, the surface of a polyolefin resin coating layer is once subjected to a surface activation treatment, then an undercoat layer is provided thereon, and a photographic emulsion layer is coated thereon. The method came to practical use. As the main component of the undercoat layer in this method, gelatin or a composition containing gelatin as a main component is known.

As described above, the subbing layer containing gelatin as a main component is generally used, but in recent years, with the increase in production of photographic supports or the cost reduction, high-speed processing of at least 150 m / min or more. Has increased, and various problems different from the conventional processing speed range have come to occur. That is, according to the conventional coating method, the higher the speed, the more rapidly the undercoat layer cannot be uniformly coated, resulting in unevenness. As a result, the undercoat layer and the photographic emulsion layer of the photographic support are Since the adhesiveness is partially weakened, the photographic emulsion layer may be peeled off from the photographic support during the development process, resulting in a fatal failure as a photographic printing paper product. Further, as a result of peeling off the photographic emulsion layer, the developing solution is contaminated, the life of the developing solution itself is shortened, and economically disadvantageous.

When a high speed coating process of a coating solution containing gelatin is carried out by a conventionally used rod blade coater, blade coater or air knife coater, the support itself cannot be uniformly supported by the rod or blade. It is impossible to uniformly apply a coating solution containing gelatin. In the case of forming the undercoat layer by the conventional rod coating method, it was attempted to obtain a uniform coating by increasing the concentration of the coating liquid and increasing the rod count, but this trial is not sufficient. It was disclosed in Japanese Patent Laid-Open No. 5-66159.

Further, when an air knife coater is used, whether it is low pressure or high pressure, high-speed coating processing, although there is a degree of difference, causes unevenness of a grain shape on the coating surface of the gelatin undercoat layer, It is very difficult to apply evenly. Further, the higher the speed, the more the gelatin coating solution will be scattered as fine water droplets, which is not only a problem in operation, but also the fine water droplets that have scattered will fall onto the surface of the support, and the water droplets will be dried while attached to the support. As a result, non-uniformity of the gelatin subbing layer is caused, and if there are many water droplets, coating failure may occur during emulsion coating, which is a very serious problem.

JP-A-5-61154 has a gelatin subbing layer containing gelatin as a main component, and the gelatin subbing layer has a gelatin concentration of 0.3% by mass or more and less than 2.0% by mass. Air pressure of gelatin solution of 500m
It is applied by a low pressure air knife coating method of maq or less,
Although a method of forming by drying is disclosed, a gelatin subbing layer having a uniform coating surface could not be obtained in the high-speed coating region.

Further, as an obstacle for high-speed coating processing, since the coating liquid constituting the undercoat layer contains gelatin as a main component, bubbles are very likely to occur, and the higher the speed, the worse the operability. It is to be. Although this foam can be removed to some extent by a device such as a defoamer, it cannot be completely removed, and a quality failure occurs on the surface of the gelatin subbing layer, and when a photographic emulsion layer is provided in this part, Adhesion between the photographic support and the photographic emulsion layer becomes insufficient, and in the worst case, the photographic emulsion layer may peel off from the photographic support in the automatic processor, which may cause a serious malfunction. Not only that, but also the quality of the product is adversely affected.

In Japanese Patent Laid-Open No. 2-189542, a support is extruded from a slit-shaped orifice at a low coating speed of about 100 m / min in order to prevent bubbles from being mixed in the coating solution of the gelatin subbing layer. A method of coating to provide a gelatin subbing layer is disclosed. However, although there is no circulation of the gelatin coating solution, in the high coating speed range, the collision between the extruded coating solution and the support traveling at high speed may cause fine water droplets or bubbles, which may cause product quality failure. Even if the slit orifice coater was adjusted, it could not be eliminated at all.

As another coating method, there is a direct gravure coating method. However, since the direct gravure method is a method of transferring the coating liquid in the cell, it has a drawback that the shape pattern of the cell remains on the coating surface. In the high-speed coating region, this problem cannot be expected to be improved simply by improving the leveling by adjusting the concentration and viscosity of the coating liquid. As mentioned above,
Japanese Patent No. 66519 discloses that a gelatin subbing layer is formed by applying a gelatin solution having a gelatin concentration of 4.0% by mass or more, but less than 10% by mass using a gravure roll of 360 lines or more and drying. Although the method is disclosed,
Even with the gravure coating method using such a fine gravure roll, it was not possible to obtain a gelatin subbing layer having a uniform coated surface in the high speed region.

Further, although the offset roll coating method is an excellent coating method capable of obtaining a smooth coating surface, it requires skill in adjustment and that the film thickness changes due to a slight change in viscosity. Furthermore, in the offset reverse coating method, when the profile of the support is non-uniform, contact with the support occurs between the roll gaps, and a catch occurs,
There is a risk that the paper will be cut and the roll will be damaged at the same time.

From these facts, it is known that there is a kiss coat coating system as a coating system which enables precise coating, and good coating surface quality can be obtained. JP-A-13-
334190 is a small-diameter reverse coating roll having a doctor blade, which faces the running direction of the coating base material.
There is a description of a coating device that arranges a backup roll under the reverse coating roll, but since there is a doctor blade immediately before the contact point between the coating base material and the roll, the coating liquid is scraped off with the doctor blade. The coating stripes generated at this time are directly transferred to the coating base material, and even in a low-speed coating area, as time increases, and as the coating speed increases, bubbles and liquid splashes in the coating liquid at the liquid raising part by the backup roll. It occurred and it was not possible to obtain a uniform coating surface quality. In addition, although the reverse kiss gravure coater is described in Japanese Patent Publication No. 11-51137, this also produces bubbles in the coating liquid when the liquid is raised, as described above.
It is not possible to obtain a uniform coating surface by transferring to the support without the bubbles disappearing. Furthermore, because of the direct coating method, the cell shape pattern of the gravure roll and the stripes generated on the gravure roll remain unchanged. Transferring to the support resulted in remarkable coating unevenness and coating streaks.

[0015]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention relates to a method for producing a photographic support and a photographic support. More specifically, the present invention is a method for producing a photographic support, which enables high-speed coating of a gelatin subbing layer coating solution on a continuously running photographic support without uneven coating and A method for producing a photographic support having a uniform profile, no coating defects in the undercoat layer due to the generation of bubbles, no paper breaks in the coater section, and excellent quality and operation, and a photographic support. The purpose is to provide.

[0016]

Means for Solving the Problems The inventors of the present invention have found the following inventions as a result of extensive studies to solve the above problems. That is, the invention of claim 1 provides a resin coating layer containing a polyolefin resin as a main component on both surfaces of a sheet-shaped substrate,
In the method for producing a photographic support, a subbing layer is provided by coating a gelatin coating solution containing gelatin as a main component on the resin coating layer on the side where the photographic emulsion is to be coated with an offset gravure coater. The offset roll is reversed with respect to the backup roll rotation direction, which is the direction of the backup roll, with a gap of at least the thickness of the support between the backup roll and the offset roll, and the support or backup just before contacting the surface of the backup roll. The method for producing a photographic support is characterized in that the photographic support is coated on the support immediately after being separated from the surface of the roll by a kiss reverse coating method in which the offset roll comes into contact.

According to a second aspect of the invention, the distance from the contact point between the support and the offset roll to the contact point between the support and the backup roll is within 100 mm, and the photographic support according to claim 1 It is a body manufacturing method.

According to a third aspect of the present invention, the ratio of the surface speed of the gravure roll to the surface speed of the offset roll (surface speed of gravure roll / surface speed of offset roll) is 1.
2. The method for producing a photographic support according to claim 1, wherein the gelatin coating solution is applied so that it becomes 0 or less.

The invention of claim 4 is characterized in that the offset gravure coater is a method for applying a gelatin coating solution using a closed doctor.
It is a method for producing the photographic support described.

A fifth aspect of the present invention is the method for producing a photographic support according to the fourth aspect, further comprising a sliding device for sliding the closed doctor in the width direction of the gravure roll. .

According to a sixth aspect of the present invention, a resin coating layer containing a polyolefin resin as a main component is provided on both surfaces of a sheet-like substrate, and gelatin containing gelatin as a main component is formed on the resin coating layer on the side where the photographic emulsion is to be coated. In a photographic support provided with an undercoat layer by coating the coating solution with an offset gravure coater, the offset roll is reversed with respect to the backup roll rotation direction, which is the running direction of the support, and between the backup roll and the offset roll. Is applied by a kiss reverse coating method in which the offset roll is in contact with the support immediately before contacting the surface of the backup roll or the support immediately after being separated from the surface of the backup roll with a space equal to or larger than the thickness of the support. The undercoat layer has a coating amount of 100 mg in terms of solid content.
/ M ² or more, which is a photographic support.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below with reference to the drawings.

First, an outline of the kiss reverse coating method used in the present invention will be described. The kiss reverse coating method of the present invention is a coating device as shown in FIG. 1 or 2. That is, the coating liquid 7 applied to the gravure roll 5 from the liquid supply pan 6 is quantified by scraping off the excess coating liquid with the doctor blade 8.
And is transferred to the offset roll 4 that rotates in the opposite direction. Gelatin coating liquid 7 transferred to offset roll 4
Is transferred and applied to the support 1 which runs and contacts the opposite direction of the offset roll 4. At that time, a space equal to or larger than the thickness of the support 1 is provided between the backup roll 2 and the offset roll 4, and immediately after the support 1 or the surface of the backup roll 2 immediately before contacting the surface of the backup roll 2. Is applied to the support 1 by the kiss reverse coating method in which the offset roll 4 contacts.

The first object of the present invention is to provide a photographic support which is capable of high-speed coating of a gelatin coating liquid in the coating of the gelatin coating liquid, has no uneven coating, and has no paper break at the coater. Although it is a manufacturing method, according to our research, when applying a gelatin coating solution using a usual reverse offset gravure coating method in which a support is in pressure contact with an offset roll via a backup roll, It was found that when the pressure support has thickness unevenness, a uniform gap in the width direction cannot be maintained, and coating unevenness occurs. This coating unevenness rarely occurs in the low-speed coating area of 150 m / min or less, but begins to occur remarkably at higher coating speeds, and becomes more remarkable as the speed increases. Further, since the support is in contact with the offset roll in a pressure state in the opposite direction via the backup roll, if the thickness of the support is uneven, the roll may break due to paper breakage. There was also.

As a result of our study, it was found that it is effective to apply the reverse offset gravure coating method, and the kiss reverse coating method in which the offset roll and the backup roll have a distance equal to or larger than the thickness of the support. When the backup roll is installed away from the offset roll, it is found that the support has flapping, and this causes uneven coating.For uneven coating caused by the flapping of the support, high-speed coating is performed. It turns out that the more you do it, the more prominent it appears. Therefore, in order to solve these problems, we use the reverse offset gravure coating method, in which the offset roll and the two backup rolls are spaced apart from each other by a distance equal to or larger than the thickness of the support and It has been found that it is effective to apply the kiss reverse coating method in which the offset roll comes into contact with the support immediately before coming into contact with the surface or the support immediately after being separated from the surface of the backup roll.

According to the present invention, by using kiss reverse,
Even if there is unevenness in the thickness of the support, it is in contact with the offset roll with a comparatively low contact force, so there will be no paper breakage, but the distance between the backup roll and the offset roll must not be greater than the thickness of the support. must not. The coating liquid plays the role of a lubricant, and the paper does not break even when the support comes into contact with the roll, but if you press it narrower than the thickness of the support or if the support has uneven thickness, the I will make paper.

In the present invention, in order to eliminate coating unevenness due to flapping of the support, the offset roll contacts the support immediately before contacting the surface of the backup roll or the support immediately after leaving the surface of the backup roll. It is applied by the kiss reverse application method. When the offset roll and the backup roll are installed at a distance, the more they are separated, and the higher the speed of coating is, the more noticeable the flapping of the support, which causes uneven coating. I will end up.

Further, according to the present invention, since the offset roll is applied by the kiss reverse coating method to the support immediately before contacting the surface of the backup roll or the support immediately after being separated from the surface of the backup roll, the offset roll is applied. The contact portion (width of contact) of the support can be made sufficiently small. If the contact area is large, the contact width between the support and the offset roll will be wide, and the coating solution will accumulate in that area, causing the coating solution to swim, which causes coating streaks and uneven coating. Easier to do.

As a specific distance between the backup roll and the offset roll in the present invention, the distance from the contact point between the support and the offset roll to the contact point between the support and the backup roll is preferably within 100 mm.

Regarding coating unevenness other than that caused by flapping, for example, even when the support has thickness unevenness, the wrap angle between the support and the offset roll (the portion where the support and the offset roll are in contact), By finely adjusting the contact pressure and the like, it is possible to obtain a coating layer with good surface accuracy without coating unevenness. Further, the same fine adjustment as above can be applied to a substrate which is easily scratched to obtain a coating layer with good surface accuracy.

The pre-measuring method of the gelatin coating solution in the present invention is not particularly limited, and a metering blade, a metering rod or the like may be appropriately used depending on the liquidity of the solution and the coating conditions. Alternatively, pre-weighing may be performed only with a gravure roll. However, when pre-measurement is performed with a metering blade or a metering rod, a streak of the coating liquid may occur, and therefore pre-measurement is preferably performed on a gravure roll. The scratched streaks generated on the gravure roll are leveled and disappear by the time the coating liquid is transferred to the offset roll and further transferred to the support.

A second object of the present invention is to provide a method for producing a photographic support having a uniform profile with very little variation in the film thickness in the width direction when the gelatin coating solution is applied at a high speed. However, as a result of our investigation, the cause of the non-uniform film thickness profile in the width direction is
It became clear that there was instability of the bead of the coating liquid formed between the gravure roll and the offset roll. That is, as shown in FIG. 5, which is an enlarged view of the portion where the bead of the coating liquid is formed, the coating liquid 7 raised by the gravure roll 5 is transferred to the offset roll 4 at a certain ratio and transferred. The coating liquid that did not exist remains on the gravure roll 5 and is recovered.
Bead 1 of the coating liquid between the offset roll 4 and the
6 is formed. At this time, what is important is the coating line 17, and if the coating line 17 stably exists at the same position in the width direction, the film thickness profile becomes uniform, and the position of the coating line 17 varies in the width direction. If so, the film thickness profile becomes non-uniform. As a result of our study, in order to keep this coating line constant, the surface speed ratio of the gravure roll 5 and the offset roll 4 (surface speed of the gravure roll 5 / surface speed of the offset roll 4) is set to 1.0 or less. It has become clear that The surface velocity ratio is preferably in the range of 0.9 to 0.6, 0.8
The range of to 0.7 is more preferable. This surface velocity ratio is 1.
If it is larger than 0, the coating line is not stable and the film thickness profile in the width direction becomes non-uniform. Although the lower limit is not particularly set, it is preferably 0.6 or more from the viewpoint of actual workability.

The third object of the present invention is at least 15
It is an object of the present invention to provide a method for producing a photographic support that does not generate bubbles and is free from coating defects in the production in a high-speed region of 0 m / min or more. Therefore, if a continuous operation operation is performed for a long time by a liquid raising system such as the normal liquid supply pan 6, bubbles will inevitably be generated in the liquid supply pan 6. Liquid pan 6
Since the gelatin subbing coating solution inside is usually circulated and a new solution is added to replenish it, it is necessary to attach a defoaming device to eliminate bubbles, but remove it completely. Was not possible, and a sufficient defoaming effect was not obtained.

This foam is small immediately after the start of the coating operation and has no particular problem, but when the circulation is started, the generation of the foam may increase depending on the coating time, the coating speed and the concentration of the coating liquid. I know. The bubbles are lifted by the gravure roll 5 and transferred to the support 1 without disappearing even between the offset rolls 4. For this reason, in order to operate stably at high speed, a means to prevent bubbles is a major issue, and as a result of our study, high-speed coating was achieved by changing the closed doctor to a liquid attachment method attached to the offset gravure coater 4. It became clear that bubbles during processing can be significantly reduced. FIG. 3 shows an example of the offset gravure coater of the present invention provided with the closed doctor 9.

Further, a schematic view of the closed doctor is shown in FIG. 4 and will be briefly described. The coating liquid 7 is circulated at the time of coating, but since it is not an open system of the liquid supply pan as shown in FIGS. 1 and 2, it is difficult for air to enter so that no bubbles are generated in the coating liquid. That is, the coating liquid 7 is surrounded by the gravure roll 5 and the steel blades 14 and 15 of the doctor fixing body 11, the coating liquid 7 is a closed system, and bubbles are generated in the coating liquid 7. There is almost no. Therefore, as a result of using the closed doctor of the present invention, the occurrence of bubbles in the circulation system almost disappears even during high-speed coating processing,
It does not affect the quality of the coated surface of the gelatin subbing layer.

When using a closed doctor,
The excess coating liquid of the gravure roll is scraped off with a steel blade and a certain amount of the coating liquid is transferred to the offset roll, but the gelatin coating liquid that is transferred from the gravure roll to the offset roll due to the difference in the pressing state in the width direction of the blade. If there is a difference in the amount in the width direction or if the tip of the steel blade is clogged with foreign matter, coating streaks will occur on the gravure roll, which will be transferred to the support as it is. Application stripes may appear on the undercoat layer of the body. As a means for eliminating the occurrence of such coating streaks due to the closed doctor, a sliding device for sliding the closed doctor in the width direction of the gravure roll is provided, so that the coating amount profile in the width direction is made uniform. Moreover, the quality and operation can be remarkably improved by removing foreign matter at the tip of the steel blade. Further, by sliding, the wear of the steel blade is made uniform, the life of the steel blade is extended, and it is advantageous in terms of cost.

An example of a closed doctor equipped with a sliding device will be described with reference to FIG. An arm 20 is attached to the closed doctor 9 and is connected to the motor 19 at a wheel 18 portion. As the wheel 18 rotates, the arm 20 slides left and right, and the closed doctor 9 slides accordingly. The driving means is not particularly limited, but a motor, a hydraulic piston or the like is used. The preferable sliding cycle is not particularly limited, but is preferably 40 to 120 times / minute, and 60 to
100 times / minute is more preferable. The amplitude is not particularly limited, but the range of 10 to 60 mm is preferable and 20 to 40 mm
Is more preferable. Both can be used under appropriate operating conditions depending on the specifications.

The fourth object of the present invention is to provide a support in which the coating amount of the undercoat layer is 100 mg / m ² or more in terms of solid content, but the ordinary reverse offset gravure coating method is a thin film coating method. It is suitable for work, but not suitable for multilayer coating. Since the present invention uses the kiss reverse coating method, it is possible to adjust the contact pressure between the support and the offset roll and the holding angle, whereby a large amount of gelatin coating liquid is applied (multilayer coating). It will be possible. Further, the multilayer coating of the undercoat layer can be performed by selecting the engraving shape and depth of the gravure roll.

The sheet-shaped substrate of the present invention may be any paper substrate generally used for photographic printing paper.
For example, in addition to natural pulp paper, synthetic pulp paper, mixed paper of natural pulp and synthetic pulp, various laminated papers can be used. These paper substrates may be blended with additives such as sizing agents, fixing agents, paper strength enhancers, fillers, antistatic agents, pH adjusters, pigments and dyes which are generally used in papermaking. In addition, surface sizing agents, surface paper strength agents,
An antistatic agent may be applied on the surface.

A polyolefin resin coating layer is formed on both the front and back surfaces of this substrate. The polyolefin resin can be selected from α-olefin homopolymers such as polyethylene and polypropylene, α-olefin copolymers and mixtures of various polymers thereof. Particularly preferred polyolefin resins are low density polyethylene, high density polyethylene, and mixtures thereof.

It is already known to add various additives such as a white pigment, a colored pigment, a fluorescent whitening agent, an antioxidant and a dispersant to a polyolefin resin, and also in the present invention, the addition of various additives to the photographic emulsion layer. These additives can be added to the surface polyolefin coating layer to be applied.

As the sheet-like substrate, various synthetic papers, films and the like can be used in addition to the above-mentioned paper substrate mainly made of natural pulp. Further, a sheet-shaped substrate coated with an electron beam curable resin, or a composite obtained by coating with a combination of an electron beam curable resin and a polyolefin resin melt extrusion is also used for the support for photographic printing paper of the present invention. You can do it.

The thickness profile of the photographic support used in the present invention is not particularly limited as long as it is within the range of the quality required for a general photographic support. The difference between the maximum thickness and the minimum thickness in the width direction of the support is preferably 20 μm or less, and 10
More preferably, it is less than or equal to μm.

In the support of the present invention, the activation treatment applied to the surface polyolefin coating layer before coating the subbing layer or to the gelatin subbing layer includes corona discharge treatment, flame treatment, activation Chemical treatment or low temperature plasma treatment can be selected as required.
A gelatin subbing layer is formed on the surface polyolefin resin coating layer thus activated.

The gelatin used in the gelatin subbing layer of the present invention may be of any type as long as it does not adversely affect the photographic emulsion layer coated on the gelatin subbing layer. For example, gelatin may be extracted from bone or extracted from skin. The gelatin extraction method may be an acidic method or an alkaline method. Furthermore, there is no particular limitation on the physical properties of gelatin, and for example, its jelly strength may be at a level generally used as an undercoat layer, and its viscosity is generally the same as that of an undercoat layer. It may be the same as that used for.

The gelatin subbing layer of the present invention contains gelatin as a main component as described above. In addition, if necessary, a hardener, a surfactant, a thickener, a white pigment and a matte. Additives such as agents, antifoaming agents, antistatic agents, antifoggants and the like may be included.

The hardener which can be used in the coating liquid for forming the gelatin undercoat layer of the present invention is not particularly limited, but for example, an inorganic hardener such as chrome alum or an aldehyde type hardener, N. -Methylol, and acetal hardener,
Epoxy hardener, aziridine hardener, mucohalogen acid hardener, active halogen hardener, dichloro-S-triazine hardener, active olefin hardener, metasulfonic acid ester hardener, or active ester hardener. There are organic hardeners such as film agents.

The surfactant that can be used in the coating solution for forming the gelatin undercoat layer of the present invention is not particularly limited, but for example, in addition to natural products such as saponin, higher fatty acid alkali metal salts and alkylsulfates. Anionic surfactants such as alkyl sulfonates and sulfosuccinates, cationic surfactants such as higher amine halogenates, alkyl vinylidyl halides and quaternary ammonium salts,
There are nonionic surfactants such as polyethylene glycol alkyl ethers, polyethylene glycol fatty acid esters, and surfactants such as amino acids.

Examples of the thickener that can be used in the coating liquid for forming the gelatin undercoat layer of the present invention include natural substances such as casein, starch and natural gas, as well as cellulose derivatives such as carboxymethyl cellulose and water-soluble substances such as polyvinyl alcohol. A polymer or the like can be used.

White pigments usable in the gelatin subbing layer of the present invention include titanium dioxide, barium sulfate, calcium sulfate, barium carbonate, calcium carbonate, white alumina, zinc oxide, silica white, antimony trioxide, titanium phosphate. and so on.

Examples of the defoaming agent usable in the coating solution for forming the gelatin undercoat layer of the present invention include methyl alcohol, ethyl alcohol, octyl alcohol, cyclohexanol, other higher alcohols, ethylene glycol, and span. Other non-ionic activators and silicone defoamers are available.

In forming the gelatin subbing layer of the present invention, it is not always necessary to carry out a low temperature coagulation treatment after coating the coating liquid and before drying, but it may be carried out. Further, the surface of the gelatin subbing layer obtained by coating and drying by any of these methods may be subjected to the activation treatment as described above.

The gelatin-containing coating liquid to be coated with the offset gravure coater used in the present invention is not particularly limited, but the gelatin concentration is preferably in the range of 0.1 to 15% by mass, and 1.0 to 5 is preferable. 0.0 mass% is more preferable. When the gelatin concentration is lower than 0.1% by mass, not only the drying load on the dryer becomes large and the economy becomes poor, but also coating unevenness is likely to occur at the time of high-speed processing. Adhesiveness with and deteriorates, which adversely affects photographic suitability. On the other hand, when the gelatin concentration exceeds 15% by mass, since the viscosity of the coating solution is high due to the high viscosity, it becomes difficult to uniformly coat it on the support, and the increase in temperature due to the temperature decrease. Due to stickiness, uneven coating is likely to occur, and gelation is easily caused, which makes management of the coating solution extremely difficult, and there are many operating problems and it is difficult to maintain quality. Not at all.

The gelatin subbing layer of the present invention is required to secure the adhesiveness between the gelatin subbing layer and the emulsion layer without adversely affecting the photographic emulsion layer. Therefore, the mass after drying is 30 mg / m ^2. It is preferable to apply the above 4
It is more preferably 0 to 300 mg / m ² . Thirty
If it is more than 0 mg / m ² , not only the economical efficiency becomes poor, but also the adhesiveness between the photographic emulsion layer and the gelatin subbing layer may become weak. Will disappear.

Regarding the range of the wet coating amount profile of the undercoat layer of the present invention, the range of the fluctuation of the wet coating amount in the width direction is within 10% of the target value for both the maximum value and the minimum value. Is preferred. Profile deflection range is 1
When it is more than 0%, when the photographic emulsion layer is coated on the undercoat layer and exposed and developed at a half density, unevenness of the same profile as the undercoat layer occurs on the emulsion layer.

On the surface of the backing resin layer of the photographic support in the present invention, various back coat layers are applied for the purpose of preventing static charge after the activation treatment such as corona discharge treatment and flame treatment. You can In addition, the backcoat layer includes JP-B-52-1820, JP-B-57-9059, JP-B-57-53940, and JP-B-58-56859.
JP-A-59-214849, JP-A-58-18414
Inorganic antistatic agents, organic antistatic agents, hydrophilic binders, latexes, curing agents, pigments, surfactants, etc. described or exemplified in No. 4 can be appropriately combined and contained.

In the production method using a closed doctor of the present invention, the engraving pattern of the gravure roll used for forming the gelatin undercoat layer is not particularly limited, but a trapezoidal lattice type is preferably used. To be
As shown in FIG. 3, the closed doctor forms a closed space filled with the coating solution by the doctor blade so that air is not mixed into the coating solution, and the doctor blade scrapes off the excess coating solution. There is also. Therefore, due to continuous operation, the doctor blade is in constant contact with the gravure roll and is therefore worn. In the case of a trapezoidal engraved grid pattern, its volume does not change significantly due to wear, and the gelatin-containing coating liquid is filled. does not change. Other engraving patterns include pyramid-shaped carved quadrangular pyramids, diagonal-shaped carved triangular or semi-circular grooves in a spiral shape, etc. It can be appropriately used depending on the operability of the.

The size of the shape of the gravure roll used in the present invention is not particularly limited, but it is preferable to use a gravure roll having an engraving pattern of 85 to 300 lines / inch. If you have a fine engraving pattern that exceeds 300 lines, 150m of coating liquid containing gelatin as the main component
Unevenness is likely to occur during high-speed coating of at least 1 minute / minute,
That is, the uniformity of the obtained coated surface is poor and is not suitable.
On the contrary, when a gravure roll having an engraving pattern of less than 85 lines is used, the surface shape pattern of the gravure roll is transferred to the offset roll, resulting in coating unevenness, that is, the obtained coating surface is inferior in uniformity. Becomes unsuitable.

Similarly, the engraving depth of the gravure roll is not particularly limited, but is 30 μm to 120 μm.
A range of m is preferred. If it is less than 30 μm, the amount of liquid cannot be sufficiently secured during high speed coating, resulting in non-uniformity.
Further, if it exceeds 120 μm, the engraving pattern of the gravure roll comes to be transferred, which is not practical.

The material of the offset roll used in the present invention can be used without particular limitation as long as it is a commonly used material. For example, ethylene propylene diene rubber, urethane rubber, a copolymer of butadiene and acrylonitrile, etc. are used.

The diameter of the gravure roll and the offset roll of the present invention is not particularly limited, but is 200 mm to 400 m.
mφ is preferable, and 250 mm to 350 mmφ is more preferable.

[0062]

The present invention will be described in detail below with reference to examples, but the contents of the present invention are not limited to the examples shown below.

Examples 1 to 8 1) Production of photographic support 0.4 mass part of alkyl ketene dimer emulsion (as ketene dimer content), 4 mass parts of cationized starch, and anion per 100 mass parts of LBKP pulp. 0.3 parts by weight of polyacrylamide, 0.4 parts by weight of polyamide epichlorohydrin resin, an appropriate amount of fluorescent whitening agent, and blue dye are added to the back surface of a base paper having a basis weight of 170 g / m ² and subjected to corona treatment to obtain a low density. Polyethylene resin (Density 0.92g / c
m ³ ; MFR = 4.0 g / 10 minutes) 50 parts by mass, high-density polyethylene resin (density 0.97 g / cm ³ ; MFR =
7.0 g / 10 minutes) 2 parts of a resin composition consisting of 50 parts by mass
Melt extrusion coating was performed at 300 ° C. with a coating amount of 8 g / m ² . Then, the surface is subjected to corona treatment, and low density polyethylene resin (density 0.92 g / cm ³ ; MFR = 8.5 g / 10
Min) 47.5% by mass, anatase type titanium dioxide content 50% by mass surface-treated with aluminum hydroxide (0.75% by mass of Al ₂ O ₃ relative to titanium dioxide) and zinc stearate 2. 20 parts by weight of a master batch of titanium dioxide pigment consisting of 5% by weight, low-density polyethylene resin (density 0.92 g / cm ³ ; MFR = 4.5 g / 10
Min) 65 parts by mass and high-density polyethylene resin (density 0.9
7 g / cm ³ ; MFR = 7.0 g / 10 min) 15 parts by mass of a resin composition at a coating amount of 30 g / m ² at 300 ° C.
Melt-extrusion coated with a photographic support (average thickness 220μ
m, maximum thickness: 235 μm, minimum thickness 205 μm).

Then, after subjecting the back resin surface to corona treatment,
Consisting of gelatin: silica dioxide matting agent (average particle size 2.0 μ) = 3: 1 as dry mass, to gelatin 15
A binder coating liquid containing a mass% of an epoxy hardener, an appropriate amount of a coating aid, and an inorganic antistatic agent was applied as a gravure roll-coat.
And the wet coating amount was adjusted to 20 g / m ² using a wire bar, and the coating amount was adjusted to dry at 130 ° C. air temperature with a hot air tunnel dryer.

Subsequently, the resin surface on the front side of the support was subjected to corona discharge treatment until the resin-coated paper was wound up,
1.5 g of gelatin, 0.3 g of a 10 mass% methanol solution of butyl paraoxybenzoate, sulfosuccinic acid-2-
5% by mass of ethylhexyl ester salt methanol and water
A kiss reverse coating method as shown in FIG. 1 which has a liquid supply pan so that a wet coating amount is 4.0 g / m ² of an undercoating coating liquid containing 0.45 g of a mixed liquid and adjusted to 100 g with water. (Gravure rolls, offset rolls, backup rolls all have a diameter of 300 mmφ) were applied on-machine at the distance between the contact points of the offset roll and the backup roll shown in Table 1 and the coating speed to obtain a photographic support.

Comparative Examples 1 to 5 The same procedure as in Example 1 was carried out except that the on-machine coating was carried out at the distance between the contact points of the photographic support, the offset roll 4 and the backup roll 2 and the coating speed shown in Table 1. . In addition, Comparative Examples 1, 3, and 5 were performed by a reverse offset gravure coating method without using a kiss method.

First, each test method and evaluation method used for evaluation of the product in these Examples or Comparative Examples will be briefly described below.

[Evaluation of Liquid Properties of Gelatin Coating Liquid] The liquid properties of the gelatin coating liquid were evaluated as follows. The operation was continuously carried out for 120 hours, and the liquid properties of the gelatin coating solution circulating in the system were visually observed and evaluated. The evaluation criteria are as follows. ⊚: Very good in operation with no bubbles or liquid splashes. ◯: Bubbles and liquid splashes are seen, but there is no practical problem. B: Some amount of bubbles and liquid splashes, but practically lower limit. X: Very large amount of bubbles and liquid splash, which is a problem in practical use.

[Evaluation of coating surface quality of undercoat layer] The support for photographic printing paper thus obtained was immersed in a 0.5% by mass aqueous solution of a dye at 25 ° C. for 10 seconds to prepare a support for photographic printing paper. After thoroughly washing with water, four sensitive evaluations were carried out by visually observing the quality of the coated surface according to the coloring state of the coated surface, and a comprehensive evaluation was performed by combining them. The evaluation criteria are as follows. (1) Non-uniformity A state in which there is uneven density without being dyed uniformly. It shows that the gelatin coating amount is non-uniform. (2) A state in which there are stripes of uneven light and shade in the running direction of the streak support. It shows that the gelatin coating amount is non-uniform in the width direction of the support. (3) A state in which streaky actual dyed portions are confirmed in the running direction of the blank support. There must be a part of the support that is not coated with gelatin. (4) A state in which an uncolored portion is present in some parts of the cissing. Whether the coating liquid is poor in wettability with the polyethylene resin coating layer and is repelled,
There is no gelatin coating layer with bubbles popping out when dried.

[Evaluation of Film Thickness Profile of Undercoat Layer] A wet coating amount profile in the width direction of a photographic support during production was measured with a moisture meter to evaluate unevenness of the film thickness profile. I went. The evaluation criteria are as follows. ⊚: Good with no profile unevenness. ◯: There is slight unevenness in the profile, but there is no practical problem. Δ: Profile unevenness is rather large, and is a practical lower limit. X: The profile has large unevenness, which is a practical problem.

The results obtained are shown in Table 1.

[0072]

[Table 1]

As is clear from Table 1, the method for producing a photographic support of the present invention in which the support immediately after being separated from the surface of the backup roll is coated by the kiss reverse coating method in which the offset roll is in contact It is understood that this is a method for producing a photographic support which is excellent in terms of operation. In the kiss reverse coating method of the present invention, it is understood that the shorter the contact point, the better the surface quality. The distance of this contact is determined by conditions such as processing speed, but if the distance is long, the support will flap and uneven coating or streaking will occur.
It is understood that the value within mm is preferable. Further, the slower the processing speed, the better the coated surface quality, and the less the generation of bubbles in the coating liquid. Comparative Example 1 of the reverse offset gravure coating method, which does not use the kiss coating method, had a remarkable occurrence of coating streaks and had no product value. Further, Comparative Examples 3 and 5 could not be manufactured because the support and the roll contacted each other and the paper was cut during the operation.

Examples 9 to 12 The same procedure as in Example 2 was carried out except that the ratio of the surface speeds of the gravure roll and the offset roll shown in Table 2 and the coating speed were changed.

Comparative Examples 6 and 7 (Comparative Example to the Invention of Claim 3) The same procedure as in Example 2 was carried out except that the ratio of the surface speeds of the gravure roll and the offset roll shown in Table 2 and the coating speed were changed.

The results obtained are shown in Table 2.

[0077]

[Table 2]

As is clear from Table 2, in Examples 9 to 12 of the present invention in which the speed ratio between the gravure roll and the offset roll was 1.0 or less, the coating surface quality and the film thickness profile of the undercoat layer were good. However, in Comparative Examples 6 and 7 in which the speed ratio of the gravure roll and the offset roll was more than 1.0, the coating surface quality showing relatively fine coating unevenness was good, but the film thickness profile of the undercoat layer was Became insufficient. Comparative Example 6 in which the film thickness profile of the undercoat layer is poor,
In Nos. 7 and 7, unevenness in density was observed when the emulsion layer was exposed and developed at a half density after being coated, and had no product value.

Examples 13 to 17 The same procedures as in Example 2 were carried out except that the liquid supply method, the coating speed, and the coating amount of the undercoat layer were as shown in Table 3.

Examples 18 to 21 Under each condition of Examples 14 to 17, the undercoat layer was applied by sliding the closed doctor at an amplitude of 30 mm at a cycle of 60 times / minute. In addition, Examples 18 to 21 are evaluated when continuously operated for 48 hours from the time of evaluation of Examples 1 to 17.

Comparative Examples 8 to 16 (Comparative Example to the Invention of Claim 4) The same procedure as in Example 2 was carried out except that the liquid supply method and the coating speed were as shown in Table 3. In Comparative Examples 14 to 16, a direct kiss reverse coating method using a liquid supply pan was used as the liquid supply method.

The results obtained are shown in Table 3.

[0083]

[Table 3]

As is clear from Table 3, the present invention using a closed doctor system as a liquid supply method can provide a photographic support excellent in coating surface quality. As a liquid supply method,
In the case of using the liquid supply pan and the fountain system, when the coating speed was higher than 150 m / min, the surface quality of the coating was deteriorated, and repelling caused by bubbles in the coating liquid occurred. Further, these phenomena tended to become more prominent as the coating speed increased. In the case of using the direct gravure kiss reverse method as the coating method, the coating streaks caused by the streaks generated on the gravure roll were remarkable and had no product value. Further, as in Examples 15 and 16, the photographic support of the present invention was a photographic support capable of heavy coating with a gelatin coating solution. The surface quality after emulsion coating was slightly improved by double-coating with the gelatin coating solution. Further, in Examples 18 to 21 in which the closed doctor was slid to perform the operation, it was found that the coating lines were improved despite the fact that the operation time was longer than the other Examples. The life of the blade was about 3 times or more longer than that of the blade without sliding and could be used.

[0085]

INDUSTRIAL APPLICABILITY According to the present invention, in a method for producing a photographic support, a gelatin subbing layer coating solution can be applied at high speed to a continuously running photographic support without causing uneven coating.
The undercoat layer has a uniform profile, and there is no coating defect in the undercoat layer due to generation of bubbles, no paper breaks in the coater section, a method for producing a photographic support excellent in quality and operation,
And a photographic support can be provided.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a kiss reverse coating method used in the present invention.

FIG. 2 is a schematic view showing an example of a kiss reverse coating method used in the present invention.

FIG. 3 is a schematic view showing an example of the kiss reverse coating method of the present invention equipped with a closed doctor.

FIG. 4 is a schematic view showing an example of a closed doctor.

FIG. 5 is an enlarged view of a portion where a bead of the coating liquid is formed.

FIG. 6 is a schematic view showing an example of a closed doctor equipped with a sliding device.

[Explanation of symbols]

1 Photographic support 2 backup roll 3 paper rolls 4 offset rolls 5 Gravure roll 6 liquid supply pan 7 coating liquid 8 Metalling device 9 closed doctor 10 Doctor fixing body 11 base blade 12 doctor axis 13 Doctor shaft fixing knob 14 Steel blade 15 Steel blade 16 beads 17 Application line 18 wheels 19 motor 20 arms

Claims (6)

[Claims] 1. An offset gravure coater in which a resin coating layer containing a polyolefin resin as a main component is provided on both surfaces of a sheet-like substrate, and a gelatin coating liquid containing gelatin as a main component is applied to the resin coating layer on the side where a photographic emulsion is to be coated. In the method for producing a photographic support in which an undercoat layer is provided by coating with, Apply the kiss reverse coating method in which the offset roll abuts on the support immediately before contacting the surface of the backup roll or the support immediately after separating from the surface of the backup roll with a space more than the thickness of the body. A method for producing a characteristic photographic support. 2. The method for producing a photographic support according to claim 1, wherein the distance from the contact point between the support and the offset roll to the contact point between the support and the backup roll is 100 mm or less. 3. The ratio of the surface speed of the gravure roll to the surface speed of the offset roll (surface speed of gravure roll / surface speed of gravure roll /
2. The method for producing a photographic support according to claim 1, wherein the gelatin coating solution is applied such that the surface speed of the offset roll) is 1.0 or less. 4. The method for producing a photographic support according to claim 1, wherein the offset gravure coater is a method for applying a gelatin coating solution using a closed doctor. 5. The method for producing a photographic support according to claim 4, further comprising a sliding device for sliding the closed doctor in the width direction of the gravure roll. 6. A sheet-like substrate is provided on both sides with a resin coating layer containing a polyolefin resin as a main component, and a gelatin coating liquid containing gelatin as a main component is offset gravure on the resin coating layer on the side to be coated with a photographic emulsion. In a photographic support provided with a subbing layer coated by a coater, the offset roll is reversed with respect to the backup roll rotation direction, which is the running direction of the support, and the thickness of the support is between the backup roll and the offset roll. With an undercoat layer applied by the kiss reverse coating method in which the offset roll is in contact with the support immediately before contacting the surface of the backup roll or the support immediately after separating from the surface of the backup roll with the above interval. there are, copy the coating amount of the undercoat layer, characterized in that it is in solid content 100 mg / m ² or more Use support.