JPH0315046A - Production of photographic support - Google Patents

Abstract

PURPOSE:To obtain a support ensuring high sharpness for a photographic printed image, inhibiting the appearance of microgrit on the resin coated surface and having satisfactory surface quality by using a specified titanium dioxide pigment. CONSTITUTION:At least one side of a paper, synthetic paper or film base is coated with a resin compsn. consisting essentially of a titanium dioxide pigment and thermoplastic resin. The titanium dioxide pigment is produced by pickling titanium dioxide and treating the surfaces of the particles with metal oxide hydrate contg. at least Al atoms in the form of anhydrous metal oxide by 0.25-1.5wt.% of the amt. of the titanium dioxide and further contg. 0-0.4wt.% silicon dioxide. Sticking to die lips is hardly caused during coating and a support preventing the appearance of microgrit, having satisfactory surface quality and ensuring high resolving power for a printed image is obtd.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention provides a resin composition in which at least one surface of a paper, laminated paper or film substrate is composed of at least a titanium dioxide pigment and a thermoplastic street resin. The invention relates to a method for manufacturing a photographic support covered with a material, and more specifically, a method for producing a photographic support with high sharpness of photographic print images and with extremely little appearance of microgrit on the coated resin surface of the photographic support. This invention relates to a method for producing a photographic support of good quality.

Furthermore, the present invention relates to a method for producing a photographic support in which die lip stains are extremely less likely to occur when the substrate surface is coated with a resin composition comprising at least a titanium dioxide pigment and a thermoplastic resin.

[Prior art]

As a photographic support, so-called photographic resin-coated paper, in which at least one side of the substrate is coated with a resin composition consisting of at least a titanium dioxide pigment and a thermoplastic resin, is well known. For example, U.S. Patent No. 3,501
, 298, discloses a technique for a photographic support in which both sides of a paper substrate are coated with polyolefin resin. 1. Since rapid photographic processing was applied, photographic polyolefin resin-coated paper, in which both sides of a base paper for photographic paper are coated with polyolefin resin, has been mainly used as a support for photographic paper. , one of the surfaces facing the image form usually contains a titanium dioxide pigment in order to impart sharpness.

What are the titanium dioxide pigments conventionally contained in the resin layer on the image forming side of photographic resin-coated paper? Natase type and rutile type titanium dioxide pigments are known. Also,
A titanium dioxide pigment whose surface is not coated, or a titanium dioxide pigment whose surface is hydrated aluminum oxide as described or exemplified in JP-A-52-35625 and JP-A-57-108849; Titanium dioxide pigments coated with inorganic substances such as hydrous silicon oxide, as well as JP-A-52-35625 and JP-A-5
8-43734, Japanese Patent Publication No. 61-26552, etc., the surface of titanium dioxide particles is coated with an organic substance such as polyhydric alcohol or its derivative, polyorganosiloxane or its derivative. Titanium pigments are known.

On the other hand, when a particularly high sharpness of the printed image is required as a photographic support, several methods of making photographic resin-coated papers are also known. For example, (1) increasing the concentration of the titanium dioxide pigment contained in the resin layer, (2) using a rutile type titanium dioxide pigment as the titanium dioxide pigment contained in the resin layer, (3) Japanese Patent Publication No. 58-
As described in No. 43734, etc., when blending a titanium dioxide pigment into a resin layer, a surfactant typified by metal soaps such as zinc stearate, calcium stearate, and zinc palmitate is added; (4) resin. As the titanium dioxide pigment contained in the layer, it is known to use a so-called organically treated titanium dioxide pigment whose particle surface is coated with the above-mentioned organic substance.

However, these manufacturing methods for photographic resin-coated paper and the photographic supports obtained by these manufacturing methods have some serious problems such as insufficient sharpness for the purpose and other problems regarding photographic suitability and manufacturing suitability. The reality is that there are some problems, but the precepts that are satisfactory have not yet been achieved.

First, if the concentration of titanium dioxide pigment in the resin layer of thermoplastic resin-coated paper is increased, a photographic support with high print image sharpness can be obtained, but there are problems with photographic suitability and manufacturing suitability. Serious problems often arise. That is, when a thermoplastic resin composition containing a titanium dioxide pigment, particularly a polyolefin resin composition, is melt-extruded and coated onto a substrate in the form of a film from a slit die, a needle-like or icicle-like shape is formed at the tip of the die lip during short extrusion. There is a tendency for such adhesion or stains (hereinafter simply referred to as die lip stains) to occur, and to make matters worse, these die lip stains tend to grow larger and larger as the melt extrusion time progresses.

If this die lip stain occurs during melt extrusion coating, streaks may occur in the vertical direction on the surface of the manufactured thermoplastic resin-coated paper, or streak-like unevenness may occur due to uneven coating amount. When the film is removed, dirt adheres to the film and is coated, causing foreign matter to appear. Therefore,
The surface quality of the thermoplastic resin-coated paper is significantly impaired, making it completely unsuitable as a photographic support that requires excellent surface quality and having no commercial value. In addition, the only way to completely remove die lip stains that have occurred is to stop production and clean the die lip or replace the die, and cleaning or replacing it requires a great deal of effort and time. There was a problem in that it resulted in a significant decrease in sexual performance.

In the first place, due to strict quality requirements for the titanium dioxide pigment in the resin layer of photographic thermoplastic resin-coated paper, the surface of the titanium dioxide particles is coated with an inorganic substance such as hydrous aluminum oxide or hydrous silicon oxide. So-called inorganically treated titanium dioxide pigments are mainly used, and so-called untreated titanium dioxide pigments, which are not subjected to any surface treatment, are rarely used. However, when using inorganic-treated titanium dioxide pigments, the more highly inorganic the treatment, the more
The occurrence of die lip stains becomes significant. On the other hand, when an untreated titanium dioxide pigment is used, die lip stains are less likely to occur, but the resin layer suffers significant photodeterioration and is susceptible to discoloration over time.

In order to solve these problems, for example, Japanese Patent Laid-Open No. 57-108849 discloses a photographic support in which a titanium dioxide pigment whose surface is lightly treated with hydrous aluminum oxide is applied to titanium dioxide. ing. However, even with this technology, there was a problem in that die lip staining occurred to some extent when the titanium dioxide pigment in the thermoplastic resin composition was significantly increased in order to achieve high sharpness of the printed image. .

Second, when a rutile-type titanium dioxide pigment is used as the titanium dioxide pigment contained in the resin layer of thermoplastic resin-coated paper, the sharpness of the printed image is improved compared to when an anatase-type titanium dioxide pigment is used. Although a photographic support with a fairly high viscosity is obtained, other serious photographic suitability problems arise. That is, first, the image form of the photographic support or the resin surface containing the titanium dioxide pigment on the side has a yellowish tinge due to the rutile type titanium dioxide pigment, making it impossible to obtain a photographic support with clear whiteness. However, there was a problem in that it was not possible to obtain clear prints on a white background.

Next, a photographic support coated with a thermoplastic resin composition containing a rutile-type titanium dioxide pigment, particularly a polyolefin resin composition, is coated on the resin surface containing the titanium dioxide pigment on the image forming side. Minute foreign matter or tiny particles called microgrit? There was a problem in that there was a remarkable tendency for this to occur.

When micrografts occur in resin-coated paper used as a photographic support, serious photographic problems occur. That is, (1) When a person is photographed on a photographic paper using a resin-coated paper with black lifts as a photographic support, if microgrit appears in areas such as the face, the photograph has no commercial value.

In the first place, the method of incorporating titanium dioxide pigment into a thermoplastic resin, especially a polyolefin resin, is to prepare a so-called masterbatch in which the pigment is contained in the resin at a high concentration in advance, and then dilute it with a diluted resin to form the desired mixture. Usually, the pigments are diluted and mixed, or a so-called compound is prepared and used, in which the pigment is contained in the resin in the desired composition ratio from the beginning.

However, when preparing a masterbatch or compound by melt-kneading a thermoplastic resin and a titanium dioxide pigment using a normal melt-kneading machine such as a Banbury mixer kneader, relatively coarse dioxide is present in the thermoplastic resin. Aggregates of titanium pigment tend to be dispersed as they are without being dispersed in a fine state, resulting in the presence of coarse pigment particles in the masterbatch or compound. As a result, microgrit is generated on the surface of the photographic support, in which at least one surface of the substrate is coated with a resin composition comprising a pigment and a resin produced using the masterbatch or the compound. . As a result of our studies, we found that when a masterbatch or compound is prepared using a rutile-type titanium dioxide pigment, relatively coarse aggregates of the titanium dioxide pigment exist in the thermoplastic resin. It was found that the tendency to become dispersed is particularly remarkable, and as a result, the appearance of micrografts is frequent. Although the reason why the aggregates tend to be dispersed as they are is not clear, it is presumed that it depends to some extent on the properties of the rutile-type titanium dioxide pigment particles, especially on the properties related to their agglomeration.

Furthermore, as a completely new and surprising finding, it has been found that there is little correlation between the tendency of micrografts to appear in photographic thermoplastic resin-coated paper and the sharpness of printed images. Further, there was also the problem that micrografts are more likely to occur as the content of titanium dioxide pigment in the resin composition increases.

Thirdly, as a result of studies by the present inventors, when preparing a masterbatch or compound by melt-kneading a thermoplastic resin and a titanium dioxide pigment, zinc stearate, calcium stearate, palmi f. Even with the addition of surfactants such as metal soaps such as zinc oxide, the sharpness of printed images on photographic thermoplastic resin-coated paper produced using the masterbatch or the compound is virtually unchanged. It turns out that the problem is that it's not expensive.

In the first place, the purpose of the metal soap added to photographic thermoplastic resin-coated paper is to improve the peelability between the cooling roll of the melt extruder and the surface of the resin-coated paper when producing resin-coated paper by melt-extrusion coating. The goal is to improve. However, as a result of studies conducted by the present inventors, completely new and surprising findings regarding the effects of metal soaps in resin-coated paper were discovered. That is,
The concentration of metal soap added when preparing a titanium dioxide pigment masterbatch or compound in the resin layer of thermoplastic resin-coated paper is 1.5% by weight relative to the titanium dioxide pigment, and the concentration is 1.5% by weight in the resin composition. On the other hand, at 0.15% by weight, the sharpness of printed images on resin-coated paper increases, but at this content, peelability is poor and micrografts occur extremely frequently. If the content is in the range of .5 to 7.5% by weight, and 0.15 to 0.75% by weight relative to the resin composition, the generation of microgrit will decrease as the amount added increases. Although the release properties were also improved, it was found that the sharpness of the printed images on the coated paper was considerably lower, sometimes lower than without the metal soap.

Furthermore, when the content exceeds this level, the occurrence of micrografts does not decrease any further, and the sharpness of printed images on resin-coated paper gradually decreases with the amount added, and the generation of oil smoke increases, causing melting. It was found that the manufacturing suitability during extrusion coating was extremely poor. As mentioned above, is there a diacid in the resin layer of thermoplastic resin-coated paper? Even if a metal soap is added when formulating a titanium pigment, there is a problem in that a photographic support with high sharpness of printed images and good surface quality without the appearance of microgrit cannot be obtained.

Fourthly, as a result of study by the present inventors, even if so-called organically treated titanium dioxide pigment is used as the titanium dioxide pigment contained in the resin layer of photographic thermoplastic resin-coated paper,
It has been found that there is a problem in that the sharpness of printed images on the resin-coated paper is not substantially high at all. That is, in the resin layer of photographic thermoplastic resin-coated paper, a metal soap such as zinc stearate is added together with an organically treated titanium dioxide pigment.
When producing resin-coated paper, if it is added in an amount that exhibits sufficient releasability and reduces the appearance of black lift, the sharpness of the printed image of the resin-coated paper will be lower than when titanium dioxide pigments without organic treatment are used. It has been found that there is a problem in that it is almost the same level or only slightly higher than that of .

More specifically, in Russian Patent No. 975576,
As a titanium dioxide pigment that can be used in the production of photographic paper, there is a description of a rutile-type titanium dioxide pigment made through a pickling process after a baking process in its production process. However, the specification only states that it can be used in the production of photographic paper, and it is incorporated into the resin layer of photographic thermoplastic resin-coated paper for the purpose of the present invention. A photographic support with high sharpness of photographic print images and a good surface quality with very little appearance of microgrit, and with good releasability between the cooling roll and the resin-coated surface and with little die lip stain. There is no mention of providing an excellent manufacturing method for the support. One of the purposes of the titanium dioxide pigments described in Russian Patent No. 975,576 is to reduce their photographic activity. However, as for the titanium dioxide pigment blended into the resin layer of thermoplastic resin-coated paper, the difference between the case where a titanium dioxide pigment made through pickling treatment and the case where a titanium dioxide pigment made without pickling treatment is used is different. When the present inventors conducted a comparative study regarding the photographic activity, no difference was observed between the two. This means that calcium carbonate and ultramarine blue, which can be added to silver halide photographic emulsions or added to the adjacent hydrophilic colloid layer and have adverse photographic effects, can be added to the resin layer of photographic thermoplastic resin-coated paper. This is also understood from the fact that even if it is added, it has almost no effect on the silver halide photographic emulsion due to the protective effect of the resin.

Furthermore, one of the purposes of the monohytitane diacid pigments described in Russian Patent No. 975,576 is to reduce their optical activity. For this purpose, the titanium dioxide pigment described in the specification has a surface that contains Ti per titanium dioxide.
Hydrolyzable aluminum compounds in the form of 0.5 to 2% by weight of a titanium compound in the form of O2 or 0.5% by weight of a hydrolyzable aluminum compound in the form of 1 to 5% by weight of kl 20 s per titanium dioxide or Sio2. It is treated with a hydrous metal oxide using a hydrolyzable silicon compound of 5 to 3 times I1%. However, as titanium dioxide pigments to be blended into the resin layer of photographic thermoplastic resin-coated paper, those whose surfaces have been treated with a hydrated metal oxide in the form of a metal anhydride of 1.5 weight or more per titanium dioxide are used. Does it cause die lip stains when used? There was a problem in that the appearance of microgrit became remarkable. ! In addition, when using a titanium dioxide pigment whose surface has been treated with 0.5 weight or more of hydrous silicon oxide in the form of SiCh per titanium dioxide, the occurrence of die lip stains is extremely severe, and the appearance of black grit is also increased. There was a problem. As mentioned above, the titanium dioxide pigment described in the specification is used for photographic thermoplastic resin-coated paper.
It was inappropriate.

[Problem that the invention seeks to solve]

SUMMARY OF THE INVENTION Accordingly, a first object of the present invention is to provide a photographic print image with high sharpness and at least one side of a paper, paper or film substrate coated with a thermoplastic resin composition containing titanium dioxide pigment. It is an object of the present invention to provide a photographic support having a good surface quality with extremely little appearance of microgrit on the resin-coated surface, and a method for producing the same. A second object of the present invention is to provide a method for manufacturing a resin-coated paper-type photographic support with high sharpness and good surface quality, with good peelability between the cooling roll and the resin-coated surface, and with little die lip stain. It is to be.

[Means and effects for solving the problem] In order to solve the above-mentioned problem, the present inventors have made the following as a result of intensive study.
Paper, paper! Alternatively, at least one side of the film substrate is coated with a resin combination consisting of at least a titanium dioxide pigment and a thermoplastic resin, and the surface is coated with a titanium dioxide pigment. More than 0.25 weight in anhydrous metal oxide form per titanium; 1.
The titanium dioxide pigment is treated with a small amount of hydrous metal oxide that contains at least aluminum atoms and has a silicon dioxide content of 0.4 weight or less (including 0), and is The object of the present invention can be achieved by using a lutherite titanium dioxide pigment made through a pickling process in which the titanium dioxide pigment is washed in an acidic state after the cleaning process and before the surface treatment process with a hydrous metal oxide. It turned out that he would be punished.

The rutile-type titanium dioxide pigment used in the practice of the present invention may be prepared by either the sulfuric acid method or the chlorine method, as long as it has been surface-treated with a specific amount of a hydrous metal oxide containing at least an aluminum atom and has been pickled. Although those produced by the method described above can also be used, from the viewpoint of designing the titanium dioxide pigment of the present invention, those produced by the sulfuric acid method are particularly preferred. In addition, the particle size is not particularly limited, but it is 0.04 μm to 0.5 μm when expressed as a number average in directional measurement using an electron microscope.
In terms of quality, especially the sharpness of the printed image, it is O. OSμm
The thickness is preferably about 0.2 μm.

As a typical method for producing the titanium dioxide pigment used in the practice of the present invention, the sulfuric acid method can be produced by the following steps.

Raw ore → Cooking/Extraction → Standing/Crystallization → Furnace filtration/Concentration → Hydrolysis → Washing → Calcining → Grinding/Sizing → Wet grinding/Classification → llm
→Surface treatment→Washing/drying→Final grinding→Titanium dioxide pigment. In the case of the sulfuric acid method, iron sulfate is usually crystallized from a solution of ilmenite treated with sulfuric acid, and the separated titanyl sulfate aqueous solution is hydrolyzed to form hydrous titanium oxide, which is then sintered to develop its pigment properties. be done. Hydrolysis of titanyl sulfate aqueous solution can be carried out by adding tetanyl sulfate solution to warm water to precipitate hydrous titanium oxide as seeds, or by using titanium water made by neutralizing titanyl sulfate or titanium tetrachloride. This can be done by a so-called external seeding method in which an oxide is added as a seed. In addition, in order to produce a luteal structure, the firing temperature is higher than that used to produce anatase structure, and sodium, potassium, zinc, etc. are added to promote the formation of the luteal structure during firing. It is carried out at 800 to 1100°C in the presence of a metal compound. Among these, the rutile-type titanium dioxide referred to in this specification is one in which 90% by weight or more, preferably 95% by weight or more of the crystal structure is converted to a rutile structure. On the other hand, in the case of the chlorine method, titanium dioxide particles are formed by vapor-phase combustion decomposition of titanium tetrachloride at high temperature in an oxygen atmosphere, and generally have a rutile structure, which can be produced by the following process. .

High purity ore or synthetic rutile → chlorination → separation/condensation → purification → preheating → calcination/decomposition → separation → crushing/sizing → wet crushing/
Classification → t+ → surface treatment → washing and drying → final grinding → titanium dioxide pigment.

The product produced by calcination or vapor phase calcination decomposition will hereinafter be referred to as titanium dioxide linker. Titanium dioxide linker is dry-pulverized using a centrifugal roller mill such as a Raymond mill or a fluid energy mill such as an air mill, and the pulverized material is suspended in water to form a titanium dioxide slurry, which is then wet-pulverized by being subjected to a wet ball mill or vibration mill. wet classification using a continuous horizontal centrifuge and/or passing through a vibrating double-deck screen (325 mesh U.S. standard screen), hereafter referred to as fines. A titanium dioxide slurry containing substantially no coarse particles of titanium dioxide is obtained. The fines, which are still in a slurry form from which coarse particles have been removed, are pickled in an acidic state, and then the surfaces of the titanium dioxide particles are treated with a specific amount of a hydrous metal compound containing at least aluminum atoms. P with filter press after surface treatment?・Titanium dioxide pigment is produced by washing with water and further pulverizing using an impact pulverizer or/and a fluid energy source.

The titanium dioxide pigment used in the practice of the present invention is typically produced by wet grinding and then pickling treatment. The method of pickling treatment is to add sulfuric acid to titanium dioxide slurry,
A format in which a mineral acid such as hydrochloric acid or nitric acid, preferably sulfuric acid, is diluted with water as necessary and added as a dilute mineral acid, for example, dilute sulfuric acid, and then washed with accumulated water and the supernatant liquid is discarded. Pickling can be carried out with running water by repeating it several times or by exchanging the supernatant liquid of the titanium dioxide slurry. The slurry concentration of titanium dioxide during pickling is preferably in the range of 100 t/t to 300 t/t, and the acidity of the slurry is preferably pH 3 or less, particularly pH 2 or less. The temperature of the slurry during pickling, that is, the pickling temperature, is preferably in the range of room temperature to 90°C, particularly in the range of 40°C to 80°C. In addition, the pickling time is preferably several times at intervals of 10 minutes to 2 hours when using a standing water method, and for over 2 hours when using a running water method. Yes.

The pickling conditions, such as acidity, pickling temperature, and pickling time, were determined under a series of combinations of experimental conditions. It can be determined by manufacturing a photographic resin-coated paper containing a titanium pigment and incorporating the titanium dioxide pigment into a thermoplastic resin layer, and measuring the number of microgrits appearing on the resin surface.

The titanium dioxide pigment used in the practice of the present invention is such that after pickling the titanium dioxide, the particle surface of the pigment is greater than 0.25 wt. %, contains at least aluminum atoms and has a silicon dioxide content of 0.4 weight φ or less (including 0)
It is produced by processing with hydrated metal oxide. If the amount of titanium dioxide treated on the surface is less than 0.25 φ, the weather resistance of the resin layer of the resin-coated paper containing the titanium dioxide pigment will not only deteriorate, but also the appearance of micrografts will increase, which is a problem. be. On the other hand, if the processing amount is 1.5 weight or more, die lip stains will occur significantly and the appearance of microgrit will also become noticeable, which is a problem. The preferred treatment amount ranges from 0.4% to 1.25% by weight, particularly preferably from 0.5% to 1.0% by weight, based on titanium dioxide in the form of anhydrous metal oxide. It is. Contains at least aluminum atoms and has a silicon dioxide content of 0.4
The hydrated metal oxide having a weight of less than 0 (including 0) is preferably surface-treated with hydrated aluminum oxide, and if necessary, a silicon dioxide content of less than 0.4% by weight,
Other hydrated metal oxides such as hydrated silicon oxide, preferably less than 0.25% by weight, or hydrated titanium oxide with a total amount of less than 1.5% by weight of anhydrous metal oxides, or The surface can also be treated with hydrous silicon aluminum oxide containing less than 0.4% by weight of silicon dioxide. In addition, as a method of treating the surface of titanium dioxide particles with a hydrous metal oxide, it is particularly preferable to pickle a titanium dioxide slurry and then adjust the pH of the titanium dioxide slurry to 5 or more, preferably 6 or more! 〈
After adjusting the pH to around 7, add a water-soluble aluminum salt to the titanium dioxide slurry, and if necessary, other water-soluble metal salts or water-soluble silicon compounds, and then change the pH in the slurry to obtain a slightly soluble hydrated aluminum oxide, If necessary, other poorly soluble oxide hydrates can be precipitated onto the titanium dioxide pigment for surface treatment. For example, a typical method for surface treatment in a reaction treatment tank equipped with a stirrer is to add a water-soluble alkaline solution such as caustic soda or potassium hydroxide to titanium dioxide slurry after pickling. 〇Adjust the pH to 7.0±1.0. Add an aluminate such as alkali aluminate to the pH-adjusted titanium dioxide slurry, and if necessary, add an aqueous solution of a water-soluble alkali such as caustic powder or potassium hydroxide, and then adjust the pH to the slurry that has become alkaline.
In order to reduce the amount of aluminum oxide and precipitate hydrated aluminum oxide on the surface of the titanium dioxide particles, the surface is treated by adding, for example, an aqueous solution of a mineral acid such as sulfuric acid or hydrochloric acid or a salt that exhibits an acidic reaction. p of titanium dioxide slurry after surface treatment
H is usually in the range of 7.0±1.0.

! Among alkali aluminates, sodium aluminate is particularly useful. ! In addition to the aluminate, the surface can be treated with other inorganic surface treating agents. In this case, it can be added at any stage before, during or after the addition of the aluminate, but it is particularly advantageous to add it before the addition of the aluminate. Inorganic surface treatment agents other than aluminate used for these surface treatments include silicon compounds such as alkali silicate and silicon tetrachloride, titanium compounds such as titanium tetrachloride, and zirconium, zinc, magnesium, manganese, etc. Various metal compounds and phosphoric acid compounds can be used.

The titanium dioxide pigment used in the practice of the present invention has a suspension electrical conductivity of 60 μ'07 cm or less after surface treatment in order to effectively prevent microgrit in photographic resin-coated paper containing the pigment. It is preferable to manufacture the product by washing it with water until it becomes solid. The electrical conductivity of a suspension of titanium dioxide pigment herein is defined as follows.

Place a magnetic stirrer rotor (manufactured by Universal Co., Ltd., length 45 mm, diameter 8 mm, Teflon coated rotor) in a 100-volume beaker, add distilled water Loom/(water temperature 21.5°C), and then Titanium dioxide pigment 1 0. Add Of. After the addition, the beaker is placed on the stand of a magnetine stirrer (manufactured by Yamato Kagaku Co., Ltd., type MH-61). After that, an electrical conductivity meter (manufactured by Toa Denpa Kogyo Co., Ltd., model CM-
5 B) conductivity cell [manufactured by Toa Denpa Kogyo Co., Ltd., type CG-2001PL (6L = 0.1): place l below the liquid level in a beaker to the extent that the electrical conductivity of the liquid can be measured (of course, the rotor (so as not to touch the electrical conductivity) and place it in the liquid so that the electrical conductivity value can be tracked over time. After installation,
Start the magnetic stirrer and turn the rotor for 1 minute.
Rotate at a rotational speed of 20 revolutions to stir the contents in the beaker to form a titanium dioxide pigment suspension, and bring the titanium dioxide pigment suspension to a liquid temperature of 21.5°C ± 0.5°C. Keep stirring for 16 minutes. Sixteen minutes after the start of stirring, the electrical conductivity of the titanium dioxide pigment suspension is read and measured at a liquid temperature of 21° C. (temperature compensation) while stirring the suspension. The electrical conductivity thus obtained is defined as the titanium dioxide pigment suspension electrical conductivity in this specification.

The electrical conductivity of the suspension advantageously used in the practice of the invention is 6.
For titanium dioxide pigments with a particle diameter of 0 μt7/cm or less, after surface treatment, the initial mother liquor is filtered using a filter press, and then the titanium dioxide pigment is washed with running water in the filter press.
It is produced by washing with water until a titanium dioxide pigment with a suspension electrical conductivity of less than 60μ77/cm is obtained. Washing conditions such as washing time, amount of water, and pressure of water were determined by subjecting the titanium dioxide cake collected under a series of combined experimental conditions to subsequent processing of drying and pulverization to obtain a titanium dioxide pigment. It can be determined by measuring the electrical conductivity of the suspension. Water washing can be carried out in the filter press by using running water, such as using the reaction solution containing titanium dioxide after surface treatment as it is, or resuspending the filter cake in the tank and replacing the accumulated water or supernatant liquid. It can be done together with or separately. Furthermore, from the viewpoint of further preventing microgrit, the titanium dioxide pigment used in the practice of the present invention preferably has a suspension electrical conductivity of 55 μσ/cm or less, and particularly preferably 50 μσ/cm or less! Yes.

The titanium dioxide pigment used in the practice of the present invention has the advantage that the titanium dioxide cake can be washed with water to more effectively prevent microgrit staining in photographic resin-coated papers containing the pigment, and to increase the sharpness of printed images. After drying, it is advantageously produced by comminution in a fluid energy mill. As the fluid energy mill, a steam mill such as a micronizer is particularly preferred, but an air mill can also be used in combination. It is especially preferable to carry out the first stage of pulverization using an impact pulverizer such as a hammer mill, and then perform the second stage of pulverization using a fluid energy mill, before pulverizing using a fluid energy mill. Yes.

The titanium dioxide pigment used in the practice of the present invention is, of course,
If necessary, various organic treatments with triethanolamine, trimethylolpropane, fatty acid metal salts, organoborisiloxane, etc. may be performed.

Thermoplastic resins used in the practice of the present invention include polyolefins, polystyrene, polyvinyl chloride, polyacrylic esters, linear polyesters, such as polyethylene tere-7-thalerate, polycarbonates, polyamides, such as nylon, cellulose esters, polyacrylonitrile, etc. Any resin can be used as long as it is capable of coating a resin film on the base paper, such as homopolymers or copolymers, such as ethylene-vinyl acetate copolymers and mixtures thereof, but in particular polyolefins, polystyrene, polyethylene tere-7-thale, Thermoplastic resins such as polycarbonate are preferred, and polyolefin resin is particularly advantageous in terms of extrusion coating properties, good adhesion to base paper, and cost. Polyolefin resins that can be used in the present invention include polyolefins such as low-density polyethylene, high-density polyethylene, polypropylene, polybutene, and polybentene. Copolymers consisting of two or more polymers or olefins such as ethylene-propylene copolymers, and mixtures thereof, with various densities and melt viscosity indexes (hereinafter simply referred to as MI), either singly or You can use a mixture of them. In addition, when the resin has a multilayer structure, resins with different properties can be used, such as using a resin with an MI of 5 to 20 as the outermost layer, and a resin with an MI of 2 to 10 as the resin in the lower layer. .

The method for incorporating the titanium dioxide pigment into the resin composition of the support for sacred photographs used in the practice of the present invention is to prepare a so-called masterbatch in which the titanium dioxide pigment is previously contained in a thermoplastic resin at a constant concentration. , use them by diluting and mixing them with a diluent resin to the desired proportion, or use titanium dioxide face f! It is usual to prepare and use a so-called compound in which a desired composition ratio of the compound is contained in a thermoplastic resin from the beginning. To produce these masterbatches and compounds, Banbury mixers, kneaders, mixed wire extruders, two-roll kneaders, three-roll kneaders, etc. are usually used, but Banbury mixers and mixed wire extrusion modes are advantageous. used for. Further, two or more types of these various crosstalk devices may be used in combination.

In addition, in order to further prevent microgrit in the photographic resin-coated paper of the present invention and to improve releasability during the production of the resin-coated paper, fatty acid metal salts are added during the preparation of the titanium dioxide pigment masterbatch or compound. It is preferable to add fatty acid metal salts to the resin layer of photographic resin covering paper. These fatty acid metal salts include:
Examples include zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, zirconium octylate, sodium palmitate, calcium palmitate, and sodium laurate. The amount added is in the range of 0.1 weight to 50 weight φ for titanium dioxide pigment, and 0.0 weight for resin composition containing titanium dioxide pigment.
The range of 1% by weight to 5% by weight is preferable.

If the content of titanium dioxide contained in the resin layer of the photographic resin-coated paper used in the present invention is 5 weight or less relative to the resin, the sharpness of the printed image will be insufficient for use as a photographic support. On the other hand, if it exceeds 40% by weight and 8%, the fluidity decreases and the extrusion properties deteriorate, and die lip stains become noticeable, which is undesirable.The range of 9% to 25% by weight is particularly preferable.

The resin layer of the photographic resin-coated paper according to the present invention preferably contains an antioxidant in order to more effectively prevent die lip stains from occurring during the production of the coated paper.

These antioxidants include phenolic and amine-based antioxidants as long as they do not cause any problems when applied to photographic resin compositions! Although various antioxidants such as antioxidants or phosphate esters can be used, they have no adverse effect on the photographic emulsion layer and can more effectively prevent die lip stains7, lj
Among these, hindered phenol antioxidants are particularly preferred. Advantageously used hindered 7-enol antioxidants include, for example, 1,3,5-trimethyl-2.4.6-}lis(3.5-di-tcrt-butyl-4-hydroxypenzyl)benzene. , tetrakis [methylene (3.5-di-tert-butyl-4-hydroxy-hydrocinnamate)] methane, octadecyl-3.5-di-tert-butyl-4-hydroxy-hydrocinnamate), 2,2 ',2N-tri,l:3,
5-di-tert-p-5'-l-4-hydroxyphenyl)flopionyloxy]ethyl isocyanurate,
1,3.5-}lis(4-tert-butyl-3-hydroxy-2,6-dimethylpenzyl)in cyanurate, tetrakis(2,4-di-tert-butylphenyl)4,4'-bi7enylenedi Phosphite, 4,4'-thiobis-(6-tert-petite/L/-Q-cresol), 2,2l-thiobis-(
6-tert-4-methylphenol),
Tris(2-methyl-4-hydroxy-5-t
ert-butyl-7enyl)butane, 2,2'-methylene-bis(4-methyl-6-tert-butylphenol), 4,4'-methylene-bis(2,6-di-tert-butylphenol), 4.4'- Ptylidene bis(3-methyl-6-tert-butylphenol), 2,6-di-tert-butyl-4-methylphenol, 4-hydroxy-methyl-2,6-di-te
Examples include rt-butylphenol, 2,6-di-tert-butyl-4-n-butylphenol, and the like. Furthermore, two or more kinds of antioxidants may be used in combination depending on the properties of the antioxidants.

The content of the antioxidant in the photographic resin composition is in the range of 5 to 1000 ppm by weight, and the content of the antioxidant in the resin composition is in the range of 10 to 500 ppm. More preferably, it is in the range of 20 to 300 ppm. Even if the amount of antioxidant is less than 5 ppm,
If it is more than 10,000 ppm, die lip stains are likely to occur, and if it is more than 10,000 ppm, the adhesion between the base paper and the resin layer will deteriorate and the casing will not be good. However, as a method for incorporating an antioxidant into the resin composition, it is possible to use a so-called compound in which the antioxidant is pre-contained in the thermoplastic resin to be used, or it is possible to use a so-called compound in which the antioxidant is pre-contained in the thermoplastic resin to be used, or to add an oxidant to a relatively high concentration. An appropriate amount of a resin containing an antioxidant may be used, or an antioxidant may be added when producing a resin composition using a crosstalk machine. Furthermore, depending on the type and content of the antioxidant used, the above methods may be combined as appropriate.

In the resin layer of the photographic resin-coated paper of the present invention, it is preferable to contain a fluorescent agent in order to improve the yellow tinge caused by the rutile-type titanium dioxide pigment and provide excellent whiteness. Various fluorescent agents such as na7talene type, stilbene type, theophene type, and coumarin type can be used as such fluorescent agents. Bis(benzoxazolyl)naphthalene compounds and/or bis(benzoxazolyl)stilbene compounds with substituents are preferred from the viewpoint of heat resistance, lead-out resistance, weather resistance, stability in photographic processing solutions, etc. is preferable. Specific examples of the na-7talene fluorescent agent and stilbene fluorescent agent that are advantageously used include those represented by the following formula.

・・・・・・(J) As a method of incorporating these fluorescent agents into a thermoplastic resin composition, when producing a master bunch or compound of titanium dioxide pigment, the fluorescent agent is incorporated. A masterbatch or compound consisting of a titanium dioxide pigment, a fluorescent agent, a thermoplastic resin, and a dispersant such as a fatty acid metal salt can be prepared and incorporated into the resin composition.

1. In the case of a polyolefin resin composition, a low molecular weight polyolefin that has a softening point lower than that of the main polyolefin resin and is solid at room temperature or/and a fluorescent agent premixed with a dispersant such as a fatty acid metal salt is used as the main polyolefin. A fluorescent agent masterbatch in which the fluorescent agent is dispersed can be prepared and incorporated into the resin composition. The content of the fluorescent agent in the resin composition is determined from the overall viewpoints of whiteness, resin processability, heat resistance, lead-out resistance, weather resistance, etc. 1 txi/rr? ~s Omy/
rr? The range is particularly good! shi< is 0.5 ryi/
The range is from rd to 10 lessons.

The resin layer on the image forming side of the photographic support according to the present invention preferably contains 9 to 25% by weight of the rutile titanium dioxide pigment according to the present invention. In the case of the resin-coated paper of the above structure, the lower resin layer may or may not contain a titanium dioxide pigment. In addition to titanium dioxide pigments, preferably fatty acid metal salts, antioxidants, and fluorescent agents, the resin layer also contains white pigments such as zinc oxide, Merck, calcium carbonate, and fatty acids such as stearic acid amide and arachidic acid amide. Organic silicone compounds such as amides and polyorganosiloxanes, blue pigments and dyes such as cobalt blue, navy blue, ultramarine blue, cerulean blue, and 7-thalocyanine blue, magenta pigments and dyes such as cobalt violet, fast violet, and manganese violet, and tinuvin. 320, P Nupin 326,
It is preferable to add a suitable combination of various additives such as an ultraviolet absorber such as Tinuvin 328 (trade name of Teva Geigy).

The photographic support produced according to the present invention is produced by a so-called extrusion coating method in which a heated and melted thermoplastic resin, preferably a polyolefin resin, is cast onto a moving substrate such as paper, synthetic paper or film. Usually both sides are coated with resin. In that case, in the case of a multi-layer structure,
The outermost resin layer on the front side and the inner resin layer of the photographic support are successively coated and then extrusion coated using the Wayuru tandem extrusion coating system or the outermost resin layer. It is preferable to use a so-called co-extrusion coating system in which multi-layer extrusion coating is performed simultaneously with the inner resin layer and the inner resin layer. Furthermore, before coating the substrate with the resin, it is preferable to subject the substrate to an activation treatment such as a corona discharge treatment or a flame treatment. The surface of the emulsion side of the photographic support has a glossy surface or a surface of JP-A-55-2 which does not affect the gloss of the surface of the photographic paper when it is made into photographic paper.
It has a finely rough surface, a matte surface, a silky surface, etc. as described in No. 6507, and the back surface is usually a matte surface, and if necessary, the front surface or both the front and back surfaces are subjected to activation treatment such as corona discharge treatment or flame treatment. can be administered. Further, after the activation process, a subbing process as described in JP-A-61-84643 can be performed.

There are no particular limitations on the thickness of the resin layers on the front and back sides of the resin-coated paper, but it is generally advantageous to extrusion coat the paper to a thickness of about 10 to 50 microns.

Substrates used in the practice of the present invention include natural pulp paper whose main component is ordinary natural pulp, mixed paper consisting of natural pulp and synthetic fibers, synthetic fiber paper whose main component is synthetic fibers, The substrate of the polyolefin resin-coated paper for photographic paper may be any of synthetic resin films such as polystyrene and polypropylene, so-called synthetic paper, or films such as cellulose acetate, polyethylene terephthalate, and polycarbonate. Natural pulp paper (hereinafter simply (referred to as base paper) is particularly preferably and advantageously used.

Examples of the pulp constituting the base paper preferably used in the practice of the present invention include JP-A-58-37642 and JP-A-60-37642.
No. 67940, JP-A-60-69649, JP-A-61
Although it is advantageous to use appropriately selected natural pulps, such as those described or exemplified in No. 35442,
If necessary, fibers other than natural pulp may be used.

Natural bulp has been subjected to conventional bleaching treatments such as chlorine, hypochlorite, and chlorine dioxide bleaching, as well as alkali extraction or alkali treatment and, if necessary, oxidative bleaching treatment using hydrogen peroxide, oxygen, etc., and combinations thereof. Wood valves of softwood pulp, hardwood pulp, softwood hardwood mixed pulp are advantageously used, and also kraft pulp,
Various materials such as sulfite halp and soda pulp can be used.

The base paper preferably used in the practice of the present invention can contain various sizing agents, polymer compounds, and additives during the preparation of paper stock slurry.

The sizing agent that can be advantageously included in the base paper preferably used in carrying out the present invention includes fatty acid metal salts and/or fatty acid metal salts.
and fatty acids, alkyl ketene dimers, alkenyl casings or alkyl succinic anhydrides, JP-A-54-147211
Eboxidized higher fatty acid amide described in JP-A No. 1983-
Examples include organic fluoro compounds described in No. 109343.

Examples of sizing agents that can be advantageously incorporated into the base paper used in the practice of the present invention include fatty acid metal salts that are fixed to the pulp with water-soluble aluminum salts such as aluminum chloride, aluminum sulfate, and polyaluminum chloride. Alternatively, sizing agents such as alkyl ketene dimer or a combination of alkyl ketene dimer and eboxidized higher fatty acid amide can be mentioned, which are fixed in the pulp with or without the use of water-soluble aluminum salts or water-soluble aluminum salts. can. The fatty acid metal salt or trigram and fatty acid preferably have 12 to 22 carbon atoms,
The amount added is preferably in the range of 0.5 to 4.0 weight per bone dry weight of pulp. In addition, the amount of water-soluble aluminum salt added as needed is in the range of 1/20 to 4/1, especially 1/10 to 4/1, based on the solid weight of the sizing agent.
A range of 1/1 is preferred. Further, the alkyl ketene dimer is preferably one in which the alkyl group has 8 to 30 carbon atoms, preferably 12 to 18 carbon atoms. Alkyl ketene dimer is usually commercially available as an emulsion thereof, and a specific example is Acopel 36 manufactured by
There are 0XC, etc. The amount added is 0.2 to 4.0 as alkyl ketene dimer per absolute dry weight of pulp.
Weight ranges are preferred.

Examples of polymer compounds that can be advantageously incorporated into the base paper preferably used in the practice of the present invention during the preparation of the paper stock slurry include cationic wet paper strength agents, cationic, anionic or amphoteric paper strength agents. As the cationic wet paper strength enhancer, polyamine polyamide epichlorohydrin resin is preferable, and the amount added is in the range of 0.05 to 4.0% by weight, especially 0.15% by weight, based on the dry weight of the pulp.
The range of 1.5% by weight to 1.5% by weight is preferable. As a specific example, Deitsuku Hercules (Koshi-made Kaimen 5 5 7
H, Kaimen S-25, Evinox P-130, etc.

Examples of cationic, anionic or amphoteric paper strength enhancers include cationic starch described or exemplified in Japanese Patent Publication No. 60-17103, cationic polyvinyl alcohol described or exemplified in Japanese Patent Application No. 62-49699, Cationic polyacrylamide described or exemplified in No. 57-185432 and JP-A No. 57-197539,
Anionic polyacrylamide described or exemplified in Japanese Patent Publication No. 62-23119 and Japanese Patent Publication No. 62-31118,
Examples include amphoteric polyacrylamide described or exemplified in JP-A-61-37613 and JP-A-59-31949, and vegetable galactomannan as described or exemplified in JP-A-59-125731.

The amount of these additions is 0.05 to 0.05 to the dry weight of the bulb.
A range of 8% by weight, particularly a range of 0.15 to 4% by weight is preferred.

In addition, the base paper preferably used for carrying out the present invention includes:
Various additives can be included when preparing the paper stock slurry. Fillers include clay kaolin, calcium carbonate, barium sulfate, magnesium silicate, titanium oxide, etc. pH regulators include caustic soda, soda carbonate, etc.
As a coloring pigment, a coloring dye, and a fluorescent whitening agent, JP-A-54-
No. 147033, patent application No. 1983-37555, patent application No. 1983
The materials described or exemplified in No. 3-96516 may be contained in appropriate combinations.

Various water-soluble polymers, antistatic agents, and additives can be added to the base paper preferably used in the practice of the present invention by spraying or tab size pressing. Examples of water-soluble polymers include similar powder polymers, polyvinyl alcohol polymers, gelatin polymers, polyacrylamide polymers, and cellulose polymers as described or exemplified in Japanese Patent Application No. 63-96516, and as antistatic agents. Alkali metal salts such as sodium chloride and potassium chloride described or exemplified in No. 63-96516,
Alkaline earth metal salts such as calcium chloride and barium chloride, colloidal metal oxides such as colloidal silica, organic antistatic agents described or exemplified in JP-A-58-82242, latex, x-r /I/ ') 'x
7) Petroleum tat emulsion carbon, styrene-acrylic acid monoacrylic acid ester copolymer, styrene-acrylic acid monobutadiene copolymer, ethylene-vinyl acetate copolymer, sterene-maleic acid monoacrylic acid Latex such as ester copolymer, clay as a pigment,
Kaolin, Merck, barium sulfate, titanium oxide, etc., p
As the H regulator, it is advantageous to contain hydrochloric acid, phosphoric acid, citric acid, caustic soda, soda carbonate, and other additives such as the above-mentioned color pigments, color dyes, and optical brighteners in appropriate combination.

For the production of the base paper preferably used in the practice of the present invention, commonly used paper machines such as a Fourdrinier paper machine and a circular net paper machine are used.
It is advantageous to employ suitable papermaking methods, such as those described or exemplified in JP-A-60240 and JP-A-61-284762. There are no particular restrictions on the thickness of the base paper, but after papermaking, the base paper may be calendered as described or exemplified in JP-A-58-37642 and JP-A-60-126397. I like the moat, its basis weight is 40υ back ~ 250 t/rr? Preferably.

The photographic support used in the present invention can be coated with various back coat layers for antistatic purposes, curl prevention, and the like. 1. For the back coat layer,
No. 20, Special Publication No. 57-9059, Poetry Publication No. 57-539
No. 40, Special Publication No. 5B-56859, % Kai Sho 59-21
Inorganic antistatic agents, organic antistatic agents, hydrophilic binders, latexes, curing agents, pigments, surfactants, etc. described or exemplified in No. 4849, JP-A-58-184144, etc. can be contained in appropriate combinations. .

The photographic support in the present invention can be coated with various types of photographic structures, and can be used for color photographic paper, black and white photographic paper, typesetting photographic paper, copying photographic paper, reversal photographic material, and silver salt. It can be used for various purposes such as diffusion transfer negatives and positives, and printing materials. For example, silver chloride, silver bromide, silver chlorobromide,
A silver iodobromide or silver chloroiodride emulsion layer can be provided. A multilayer silver halide constituent layer can be provided by incorporating a color coupler in the silver halide photographic emulsion layer.

Further, a silver salt diffusion transfer image-receiving layer can be provided by containing physical development nuclei. As the binder for these photographic structure layers, in addition to ordinary gelatin, hydrophilic polymeric substances such as polyvinylpyrrolidone, polyvinyl alcohol, and polysaccharide sulfate ester compounds can be used. Also,
The photographic bottom layer described above can contain various additives.

For example, sensitizing dyes such as cyanine dyes and merocyanine dyes; chemical sensitizers such as water-soluble gold compounds and sulfur compounds; anti-capri agents or stabilizers such as hydroxy monotriazolopyrimidine compounds and mercapto heterocyclic compounds; Hardeners include formalin, vinyl sulfone compounds, aziridine compounds, etc. Coating aids include benzenesulfonate, sulfosuccinic acid ester salts, anti-staining agents, dialkylhydroquinone compounds, and other optical brighteners. A suitable combination of water-soluble iridium, water-soluble rhodium compounds, etc. can be contained in the silver halide during production and dispersion of silver halide.

The silver halide photographic material according to the present invention can be exposed to light as described in "Photographic Light-sensitive Materials and Handling Methods" (Kyoritsu Shuppan, written by Goro Miyamoto, Photographic Technology Course 2), depending on the photographic material.
Processes such as development, stopping, fixing, bleaching, stabilization, etc. are carried out, and in particular, multilayer silver halide color photographic materials that undergo one-bath bleach-fixing treatment after color development are CD-[[, CD-ill
/ (the above two compounds are trade names of Kodak Co.), droxychrome (trade name of May and Peker Co.), and any other crude drug color developer can be used for processing. Benzyl alcohol, thallium salt,
A development accelerator such as phenidone may also be included. In addition, it is also possible to process with a developer substantially free of benzyl alcohol. A useful one-bath bleach-fix solution is a solution of a metal salt of an aminobocarboxylic acid (e.g., a ferric complex salt such as ethylenediaminetetraacetic acid, propylenediaminetetraacetic acid, etc.), and as a fixing agent, sodium thiosulfate, Ammonium thiosulfate and the like are useful. Such a bleach-fix solution can contain various additives. For example, desilvering accelerators (e.g., U.S. Pat. No. 3,512
．． mercaptocarboxylic acids described in No. 979, mercapto heterocyclic compounds described in Belgian Patent No. 682,426), antifouling agents, pH adjusting or pH buffering agents, hardening agents (e.g. sulfuric acid). Various compounds such as magnesium, aluminum sulfate, potassium alum, etc.), surfactants, etc. can be contained in combination. Although such single bath bleach-fix solutions may be used at a variety of pHs, a useful pH range is from pH 6.0 to 8.0.

〔Example〕

Next, in order to explain the present invention more specifically, examples will be presented.

Example 1 A rutile-type titanium dioxide linker produced according to the manufacturing process of rutile-type titanium dioxide pigment by the sulfuric acid method described in the main text of the specification was crushed and sized, and then wet-pulverized and classified to obtain coarse particles of dioxide. A titanium dioxide slurry substantially free of titanium was obtained. This slurry was placed in a pickling treatment tank, and then diluted sulfuric acid was added to the slurry until the pH of the slurry was 1.0.
, 2.0 and 4.5, respectively. on the other hand,
A control sample was prepared without adding dilute sulfuric acid. Pickling is carried out using the standing water method, and the slurry temperature during pickling is 45℃.
The pickling time was 30 minutes for one pickling with pooled water, and this was repeated three times for pickling.

The pH of the slurry was then adjusted to about 9 with sodium hydroxide.
．． 2, and after heating the slurry to about 70°C,
Adding an aqueous sodium aluminate solution or/and an aqueous sodium silicate solution to titanium dioxide on a dry basis in an amount calculated in the form of AL20 s or/and S i02 and calculated in the weight amount listed in Table 1, Then, it was held for 30 minutes. In addition, when performing surface coating treatment with hydrous titanium oxide, before increasing the pH of titanium dioxide slurry with sodium hydroxide, add Ti to dry standard titanium dioxide.
An amount of aqueous titanyl sulfate solution calculated in the form of O2 was added in an amount of weight according to Table 1.

? Then, the pH of the slurry was adjusted to 7.20 by adding polysulfuric acid.
The slurry was further aged for 2 hours. After ripening,
The initial mother liquor of the titanium dioxide slurry surface-treated with a hydrous inorganic oxide is filtered through a filter press, and then the titanium dioxide cake in the filter press is washed with running water, as defined in the text of the specification for titanium dioxide pigments. The suspension was washed with water under predetermined washing conditions in a housing with an electrical conductivity of 45 μU/cm.

Thereafter, the titanium dioxide cake is dried, impact-pulverized with a hammer equipped with a quantitative feeder, and further finely pulverized with a steam mill to produce titanium dioxide pigments of the present invention and non-inventive titanium dioxide pigments listed in Table 1. did.

Thus, low density polyethylene (MI=7, density 0.9
70 parts by weight of titanium dioxide pigment, 30 parts by weight of titanium dioxide pigment, and 1.5 parts by weight of zinc stearate were thoroughly kneaded at 150° C. using a Banbury mixer to obtain the above titanium dioxide pigment master patches.

On the other hand, a mixed paper stock of 50 parts by weight of bleached hardwood kraft pulp and 50 parts by weight of bleached softwood sulfite pulp was beaten to a Canadian ● Standard ● freeness of 310 m, and for 100 parts by weight of pulp, 3 parts by weight of cationized starch and anionic 0.2 parts by weight of polyacrylamide, alkyl ketene dimer emulsion (as ketene dimer content)
0.4 parts by weight of polyaminobolyamide and 0.4 parts by weight of chlorohydrin resin were added to form paper having a basis weight of 160η.

The obtained wet paper was dried at 110°C, and then 3 parts by weight of carboxy-modified polyvinyl alcohol and 0.0 parts of optical brightener were added.
5 parts by weight, blue dye 0.002 parts by weight, 0 citric acid
．． 25tβ of an impregnating solution consisting of 2 parts by weight and 97 parts by weight of water.
Impregnated, dried with hot air at 110°C, and further Ic linear pressure 9
After supercalendering at 0 Vcm, both surfaces thereof were subjected to corona discharge treatment to produce a base paper for photographic resin-coated paper.

Next, apply high-density polyethylene (density 0.9
A 1:1 mixture of 60 f shoulder, MI=s) and low density polyethylene (density 0.923 f/cd, MI=5) was coated to a thickness of 30μ using a melt extrusion coater at a resin temperature of 330°C. . Next, the masterbatch 30 of the titanium dioxide pigment described above is applied to the surface of the base paper! parts, high-density polyethylene (density 0.960η'm, MI=5)2
A resin composition containing 0 parts by weight and 50 parts by weight of low-density polyethylene (@0.923η times, MI=5) was coated at a resin temperature of 330°C to a thickness of 30μ, and the present invention and the present invention Polyethylene resin coated papers containing non-inventive titanium dioxide pigments were each produced. At that time, the surface of the polyethylene containing titanium dioxide pigment was processed into a completely flat glossy surface, and the surface quality of the back polyethylene was processed into a paper-like matte surface.

The number of microgrits generated on the polyethylene resin coating surface containing the titanium dioxide pigment of the thus obtained polyethylene resin-coated paper was visually counted.

In addition, die lift stain was measured as follows.

Using a screw extruder with an extrusion port diameter of 65 mm and a melt extruder with a T-die of 750 mm width, the melt temperature was 320 mm.
After melt-extruding for 2 hours at a temperature of 10° C. and a screw rotation speed of 10 rpm, the number of stains generated on the die lip was counted and measured.

Next, in order to measure the sharpness of printed images, color photographic paper was produced using the above-mentioned photographic resin-coated paper as a support. First, a puff coat layer of 0.1/m'' was coated on the back side of photographic resin-coated paper with a dry weight ratio of colloidal silica:styrene acrylic latex = 1:1 after corona discharge treatment. After corona discharge treatment on the front resin surface containing titanium dioxide pigment of resin-coated paper for printing, there is a blue-sensitive emulsion layer containing a yellow-coloring coupler, an intermediate layer containing a color mixing preventive agent, a green-sensitive emulsion layer containing a magenta-coloring coupler, and an ultraviolet-ray emulsion layer containing a yellow coloring coupler. A color photographic paper was obtained by providing an ultraviolet absorbing layer containing an absorber, a red-sensitive emulsion layer containing a cyan color-forming coupler, and an i-layer.Each color-sensitive emulsion layer had a salt odor equivalent to 0.6 f/rr? with silver nitrate. In addition to gelatin, which contains silver halide and is necessary for the production, dispersion, and film formation of silver halide, appropriate amounts of anticapri agents, sensitizing dyes, coating aids, hardeners, thickeners, and appropriate amounts of filter dyes, etc. including.

A resolution capchart is closely attached to the obtained color photographic paper,
A test sheet was obtained by exposure to green light and color development. This test sheet was measured with a microdensitometer and calculated using a personal computer according to a conventional method to calculate the sharpness of the magenta layer image using CTF (Con
trust TransferFunction;
The sharpness of the printed image on the photographic resin-coated paper was determined by determining the contrast transfer function (contrast transfer function). Note that the larger the CTF value, the higher the sharpness of the printed image.

The results obtained are shown in Table 1.

(Left below) ? As can be seen from Table 1, as the titanium dioxide pigment in the resin layer of the resin-coated paper, the surface contains more than 0.25% by weight and less than 1.5% by weight in the form of metal anhydride per titanium dioxide. It is treated with a hydrated metal oxide that contains at least an aluminum atom and has a silicon dioxide content of 0.4 weight or less (including 0), and is treated with a hydrated metal oxide after the firing step in the titanium dioxide pigment manufacturing process. Photographic supports in the present invention (samples A1 to &7) using titanium dioxide pigments made through a pickling process in which the titanium dioxide pigments are washed in an acidic state before the surface treatment process with metal oxides are as follows:
It can be clearly seen that this is an excellent photographic support with very little die lip staining during production, significantly preventing the formation of microgrit, and high resolution of printed images.

On the other hand, it can be seen that the photographic supports other than those of the present invention (samples A8 to A14) each have their own problems. That is, when anatase type titanium dioxide pigment is used (sample boiling 14
), the resolution of the printed image is low, and when a rutile-type titanium dioxide pigment that has not been subjected to pickling treatment (Sample 9), micrografts occur extremely frequently.

In addition, when the surface was treated with 1.5 weight or more of hydrated metal oxide in the form of anhydrous metal oxide per titanium dioxide (sample AIO, A12) and in the form of Si02 per titanium dioxide, When using a surface treated with 0.5% by weight or more of hydrous silicon oxide (sample A 11,
In A13), there is a significant occurrence of die lip stains, and there is also a tendency for microgrit to increase. Furthermore, when the surface was treated with less than 0.25 weight of hydrated metal oxide in the form of anhydrous metal oxide per titanium dioxide (sample A8) - HCL type) after 120 hours of irradiation. The sample surface turns yellow and weather resistance is poor, which is a problem.

Example 2 Example 1 was carried out in the same manner as in Example 1, except that the following composition was used as the resin composition for the front side containing titanium dioxide pigment of resin-coated photographic paper.

1. As an antioxidant, tetrakis[methylene (3,
Low-density polyethylene (MI=7, density 0.918 f/aA) with methane added in the amount shown in Table 2 (MI=7, density 0.918 f/aA) 0 parts by weight, 50 parts by weight of the same rutile-type titanium dioxide pigment as Sample &2 and Sample Boiled 9 listed in Table 1, and 2.5 parts by weight of zinc stearate were thoroughly kneaded at 150°C using a Pamperley mixer. A master patch of titanium dioxide pigment containing antioxidants was created.

Next, master x f26 of the above titanium dioxide pigment
Parts by weight, high density polyethylene (density 0.9602/1,
? vII=5) and 54 parts by weight of low-density polyethylene (density 0.923 t/d, MI=5) were blended and used as the front resin composition.

The results obtained are shown in Table 2.

The difference between Example 1 and Example 2 is that the titanium dioxide pigment concentration in the resin layer is different. The titanium dioxide pigment concentration in the resin layer in Example 1 is 9% by weight, and the concentration in Example 2 is 13% by weight. Comparison of results in Table 1 and Table 2 (comparison of sample J1≦2 and sample Todoroki 15 and sample A9 and sample 12
3), it is clearly seen that when the titanium dioxide pigment concentration in the resin layer is increased, the resolution of the printed image is significantly increased, which is preferable (ix), and the occurrence of die lip stains is increased. However, as understood from the results in Table 2, as a preferred embodiment of the present invention, by adding an appropriate amount of an antioxidant to the resin composition containing the rutile titanium dioxide pigment of the present invention, It can be seen that the formation of die lip stains is well prevented. The amount added is preferably in the range of 10 to 500 ppm based on the resin composition! It is particularly preferably in the range of 20 to 300 ppm,
On the other hand, it can be seen that die lip contamination actually increases when it exceeds 10001)I)m. As described above, the photographic support according to the present invention to which an appropriate amount of antioxidant is added can be manufactured using a die-free method. There are very few precautions to keep from getting dirty.
It is clearly seen that this is an excellent photographic support in which the occurrence of black lift was significantly prevented and the resolution of the printed image was significantly high.

Example 3 Antioxidant used in Example 2 Tetrakis [methylene (3
．． Octadecyl-3.5-di-tert-butyl-4-hydroxy-hydrocinnamate)
5-di-tert-butyl-4-hydroxy-hydrocinnamate, 2. 2', 2'-tris[3,5-di-tert-butyl-4-hydroxy-7enyl]probionyloxy]ethyl isocyanurate case or 1,3
．． 5-}Squirrel (4-tert-petitroux3-
The same procedure as Example 2 was carried out except that hydroxy-2,6-dimethylbenzyl)in cyanurate was used. As a result, we have obtained an excellent photographic support that has very little die lift staining during the production of the photographic support, significantly prevents the generation of microgrit, and has a significantly high resolution of printed images. Ta.

? Example 4 Example 2 was carried out in the same manner as in Example 2, except that the following composition was used as the resin composition for the front side containing titanium dioxide pigment of resin-coated photographic paper.

As an antioxidant, 1,3,5-}IJs(4-tert-butyl-3-hydroxy-2,6-dimethylbenzyl)in cyanurate was added in advance to 50 ppm in the resin composition on the front side. Compounded low density polyethylene (MI = 7, density 0.918ψtA
), 50 parts by weight of the rutile-type titanium dioxide pigment of Sample Todoroki 2 listed in Table 1, and 2.5 parts by weight of zinc stearate were thoroughly kneaded at 150°C using a Pamperley mixer to obtain a titanium dioxide pigment. Created a master patch. 0.28 parts by weight of the fluorescent agent (G) described in the main text of the specification and 0.28 parts by weight of zinc stearate were thoroughly mixed in advance, and the mixture was used to prepare a titanium dioxide pigment master patch. 40 parts by weight of the same low-density polyethylene was thoroughly kneaded at 135° C. using a lab blaster to form a fluorescent agent master patch.

Next, the master patch 26 of the titanium dioxide pigment described above is applied.
parts by weight, fluorescent agent master patch 2.2 parts by weight, high density polyethylene (density 0.9605'/d, MI=5) 20
Weight parts and low density polyethylene (density 0.923 t/
cwt, MI=5) by blending 52.8 parts by weight,
It was used as a resin composite on the front side.

As a result, during the production of photographic supports, the formation of die lip stains is extremely small, the occurrence of microgrit is significantly prevented, and therefore the surface quality is good and the resolution of printed images is significantly high. Furthermore, an excellent photographic support having high brightness and extremely high whiteness was obtained.

Example 5 Instead of the fluorescent M(G) used in Example 4, fluorescent agents (A) to (F) or (H) to (K) described in the main text of the specification were used.
The same procedure as in Example 4 was carried out except that .

As a result, an excellent photographic support similar to that of Example 4 was obtained.

〔Effect of the invention〕

According to the present invention, during the production of photographic supports, the generation of die lip stains is extremely small, the generation of microgrit is significantly prevented, and therefore the surface quality is good and the resolution of printed images is significantly high. An excellent resin-coated paper-type photographic support can be provided. Furthermore, according to the present invention, die lip stains are extremely less likely to occur during the production of photographic supports.
In addition, it is an excellent resin-coated paper type for photography that prevents the occurrence of micrografts and therefore has good surface quality, and the resolution of the printed image is significantly high.In addition, the brightness and whiteness are extremely high. It can provide support.

-607-

Claims (12)

[Claims] (1) In a method for producing a photographic support in which at least one surface of a paper, synthetic paper or film substrate is coated with a resin composition comprising at least a titanium dioxide pigment and a thermoplastic resin, the surface of the substrate is coated with a resin composition comprising at least a titanium dioxide pigment and a thermoplastic resin. contains at least aluminum atoms in an amount of more than 0.25% by weight in the form of anhydrous metal oxide and less than 1.5% by weight per titanium dioxide, and not more than 0.4% by weight as silicon dioxide (
0), and the titanium dioxide pigment is washed in an acidic state after the firing step in the titanium dioxide pigment manufacturing process and before the surface treatment step with the hydrous metal oxide. A method for producing a photographic support characterized by using a rutile titanium dioxide pigment produced through an acid washing process. (2) The method for producing a photographic support according to claim 1, wherein the hydrated metal oxide is hydrated aluminum oxide. (3) The method for producing a photographic support according to claim 1 or 2, wherein the titanium dioxide pigment is pulverized using a fluid energy mill. (4) The method for producing a photographic support according to claim 3, wherein the fluid energy mill is a steam mill. (5) The method for producing a photographic support according to claim 1, 2, 3 or 4, wherein the thermoplastic resin is a polyolefin resin. (6) The method for producing a photographic support according to claim 5, wherein the polyolefin resin is a polyethylene resin or a modified polyethylene resin. (7) The method for producing a photographic support according to claim 1, 2, 3, 4, 5 or 6, wherein the resin composition contains a higher fatty acid metal salt. (8) The method for producing a photographic support according to claim 1, 2, 3, 4, 5, 6 or 7, wherein the resin composition contains an antioxidant. (9) The method for producing a photographic support according to claim 8, wherein the antioxidant is a hindered phenolic antioxidant. (10) Claim 1, wherein the resin composition contains a fluorescent agent.
, 2, 3, 4, 5, 6, 7, 8 or 9. (11) The method for producing a photographic support according to claim 10, wherein the fluorescent agent is a bis(benzoxazolyl)naphthalene compound having a substituent or/and a bis(benzoxazolyl)stilbene compound having a substituent. (12) Claims 1, 2, 3, 4, wherein the rutile titanium dioxide pigment contained in the resin composition is 9 to 25% by weight;
5, 6, 7, 8, 9, 10 or 11.