JPH0426098B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a photographic resin-coated paper, and more particularly to a photographic resin-coated paper which prevents poor appearance and poor photographic suitability due to poor dispersion of an inorganic blue pigment. In recent years, with the rapid development of photographic paper, resin-coated paper, in which both sides of a paper base are coated with polyolefin resin, has come to be used as a photographic support. The polyolefin resin layer on the side of the polyolefin resin-coated paper on which the photographic emulsion layer is coated contains white pigments such as titanium oxide, zinc oxide, and talc in order to provide high reflectance and hiding power. Blue for the purpose of visually making it look white.
It was common to include colored pigments such as magenta or purple. Ultramarine blue, which has excellent heat resistance, is known as a coloring pigment such as blue, magenta, or purple that is used to visually make it look white. However, when coated with a polyolefin resin containing ultramarine and white pigment, Aggregates of 50 to 500μ are generated due to poor dispersion.
As a support for photographic paper, the appearance was unfavorable. Furthermore, when photographic paper is manufactured by coating a silver halide photographic emulsion layer on such a support for photographic paper, there is a problem that desensitization of the emulsion and fogging occur around the ultramarine aggregates. It was hot. To this end, various methods have been attempted to improve the dispersibility of ultramarine blue in polyolefin resins. For example, when incorporating ultramarine blue into polyolefin resin, zinc stearate is used as a dispersant.
A method of adding surfactants such as metal soaps such as magnesium stearate and zinc palmitate, fatty acid amides such as stearic acid amide and arachidic acid amide, a method of using ultramarine whose surface is coated with a surfactant, In addition, a so-called masterbatch containing ultramarine at a high concentration in a polyolefin resin is prepared in advance, and this is diluted and mixed with a diluted resin to create a masterbatch whose ultramarine concentration is lower than the previous masterbatch but still higher than the final use concentration. Alternatively, a method is known in which the material is repeatedly prepared several times and then finally diluted and mixed with a diluted resin before use. However, even when these methods were used, although the ultramarine blue aggregates were somewhat reduced, the results were still not satisfactory. SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a photographic resin-coated paper which is free from poor appearance and poor photographic suitability due to ultramarine aggregates. As a result of intensive research by the present inventors, it is an object of the present invention to provide a photographic resin-coated paper in which the paper support is coated with a polyolefin resin containing ultramarine, in which the ultramarine is processed by an impact mill or/or a fluid energy pulverizer. It has been found that this can be achieved by containing ultramarine in the resin layer, which has been crushed by ultramarine and has a suspension electrical conductivity as defined below of 200 μ/cm or less. Ta. The ultramarine suspension electrical conductivity referred to here is defined as follows. Magnetic stirrer rotor in a 100ml beaker (sold by Universal Co., Ltd., length 45
A Teflon-coated rotor with a diameter of 8 mm) was installed, and 100 ml of distilled water (water temperature 21.5°C) was added, followed by 10.0 g of ultramarine blue. Subsequently, the beaker is placed on the stand of a magnetic stirrer (manufactured by Yamato Kagaku Co., Ltd., type MH-61). Then, the conductivity cell [manufactured by Toa Denpa Kogyo Co., Ltd., type CG-2001PL (O = 0.1)] of an electrical conductivity meter (manufactured by Toa Denpa Kogyo Co., Ltd., model CM-5B) was placed under the liquid level in the beaker. Place it in the liquid to the extent that the electrical conductivity can be measured (of course, do not touch the rotor),
To enable tracking of electrical conductivity values over time. After installation, start the magnetic stirrer and rotate the rotor at a rotational speed of 420 revolutions for 1 minute to stir the contents in the beaker to form an ultramarine suspension. Liquid temperature 21.5℃±0.5
Stir for 16 minutes while keeping at °C. Sixteen minutes after the start of stirring, the electrical conductivity of the ultramarine suspension is read and measured while stirring the suspension at a liquid temperature of 21.5°C. The electrical conductivity thus obtained is defined as the ultramarine blue suspension electrical conductivity in this specification. The present invention provides a photographic polyolefin resin-coated paper which is produced using a resin composition consisting of ultramarine blue and a polyolefin resin, and which has a remarkable reduction in aggregates due to poor dispersion of ultramarine blue and has good surface quality. It is particularly effective for Further, the photographic resin-coated paper of the present invention exhibits little fogging or desensitization when coated with a silver halide photographic emulsion, and is extremely suitable for silver halide photographic printing paper. The ultramarine used in the practice of the present invention includes pure blue, violet-blue, as long as the electrical conductivity of the suspension as referred to in this specification is 200μ/cm or less.
Purple, magenta, dark, medium, and light colors can all be used. Further, various particle sizes can be used, such as those having a particle size of 0.2 to 8 microns as measured by a light transmission method, and those having a water content of 2.0% or less, preferably 1% or less. Regarding their production methods, kaolin,
A raw material composition comprising soda carbonate, sulfur, a carbonaceous reducing agent, and, if necessary, silicic acid when producing ultramarine blue having magenta color as a color component, is mixed and pulverized. The mixed pulverized product is packed in a pot and fired at 700°C to 800°C with no air allowed. During cooling, some air is allowed to enter. After cooling, the fired product is washed with water, and further wet-pulverized by a wet ball mill or a vibration mill, using a continuous horizontal centrifuge or/and a vibrating double deck screen (for example, manufactured by Tokuju Kosho Co., Ltd.). TM−
100−2S, 325 mesh U, S, standard screen)
Wet classification is performed by passing the After that, the wet-pulverized classified product is passed through a centrifugal dehydrator, a vacuum filtration machine, or a filter press, dried with a dryer such as a band dryer, and further pulverized with a pulverizer to produce the product. However, in this specification, ultramarine whose suspension electric conductivity is 200 μ/cm or less is used in the water washing process of the fired product during the ultramarine production process or the water washing process separately provided to suit this purpose. It is produced by washing with water until an ultramarine blue having a suspension electrical conductivity as referred to herein of less than /cm is obtained. Water washing can be performed in various ways. For example, in the washing process of fired products or a separate washing process, if a filtration method is used, the ultramarine blue on or in the material can be washed away with running water, and if a washing tank is used, the ultramarine blue can be washed away in the tank. Some ultramarine blue or ultramarine blue suspended in a tank, or even ultramarine blue wrapped in wood and contained in a tank, can be washed with standing water or running water, especially running water in a manner that replaces the supernatant liquid. Further, water washing can be performed subsequent to the dehydration step of the ultramarine blue. That is, it is also possible to pass the initial mother liquor from the ultramarine suspension using a filter press, vacuum filtration machine, etc., and then wash the ultramarine cake in the filter press and the ultramarine cake on the material with running water. Furthermore, water washing can be performed by combining the various methods described above. Washing conditions such as washing time, water amount, and water pressure are determined by subjecting the ultramarine samples collected under a series of combination experimental conditions to subsequent regular manufacturing process treatments, such as at least subsequent treatments such as drying and pulverization. It can be determined by measuring the electrical conductivity of a suspension of the ultramarine pigment.
Furthermore, in order to further prevent ultramarine aggregates, the ultramarine in the present invention preferably has a suspension electrical conductivity of 150 μ/cm or less, particularly 100 μ/cm or less. More preferred. If the ultramarine blue obtained in this way has a suspension electrical conductivity of 200μ/cm or less,
Although it is effective in preventing the generation of ultramarine aggregates, the generation of ultramarine aggregates can be even more significantly prevented by using an impact mill or/and a fluid energy crusher to crush the ultramarine cake after drying in the above process. can do. That is, compression (e.g., roll crusher mill), percussion (e.g., hammer mill), or shear (attrition or rubbing) type (e.g., centrifugal roller mill) mills are used. When ultramarine blue is crushed after drying, the prevention of ultramarine aggregates from occurring is unsatisfactory. However, using an impact type crusher called an impact mill or/and a fluid energy crusher,
The generation of ultramarine agglomerates can be significantly prevented only when ultramarine having a suspension electrical conductivity as referred to herein of 200 μ/cm or less is crushed, but on the other hand, using an impact mill or/and a fluid energy crusher Even if the dried ultramarine blue is pulverized by drying, if the suspension electrical conductivity of the ultramarine blue as used herein is 200 μ/cm or more, the prevention of ultramarine aggregates from occurring is likely to be quite insufficient. This has led to the present invention. The impact mill used to carry out the present invention is a type of crusher that rotates a hammer in a case at high speed and performs crushing by impact action, and there are two types: fixed hammer type and swing hammer type. However, a repulsive crusher called a hammer crusher is not included. In particular, for carrying out the present invention, a swing hammer type in which the main shaft rotates at a particularly high speed of over several thousand revolutions per minute is preferable because it effectively prevents the generation of ultramarine agglomerates. In addition, from the viewpoint of better preventing the generation of ultramarine aggregates, a fluid energy crusher that is advantageously used in carrying out the present invention utilizes the energy of high-pressure gas to accelerate particles at high speed in an air stream. A type of pulverizer that performs pulverization by collision between each other and between particles and a wall,
This includes air mills, steam mills, etc.
A steam mill that utilizes the energy of superheated steam is particularly advantageous in that it particularly prevents the generation of ultramarine agglomerates. Furthermore, in order to exhibit the effects of the present invention even more markedly, an impact mill and a fluid energy crusher may be used together. Polyolefin resins used in the practice of the present invention include homopolymers such as low-density polyethylene, high-density polyethylene, polypropylene, polybutylene, and polypentene, and copolymers consisting of two or more of olefins such as ethylene-propylene copolymers. It is a mixture of various densities and melt viscosity indexes (melt index:
(hereinafter simply abbreviated as MI) can be used alone or in combination. In addition to white pigments such as titanium oxide, zinc oxide, talc, and calcium carbonate, the resin layer of the photographic resin-coated paper of the present invention contains stearic acid amide,
Fatty acid amides such as arachidic acid amide, fatty acid metal salts such as zinc stearate, calcium stearate, magnesium stearate, calcium palmitate, pigments and dyes other than ultramarine such as cobalt violet, antioxidants, fluorescent whitening agents, It is preferable to add various additives such as ultraviolet absorbers in appropriate combinations. In particular, the amount of titanium oxide added to the resin layer on the side of the resin-coated paper on which the photographic emulsion layer is coated is 5% by weight based on the resin layer.
A range of 20% by weight is preferred. In addition, the amount of ultramarine added to the resin layer in combination with a white pigment such as titanium oxide is 0.01% by weight based on the resin layer.
A range of from 1.0% to 1.0% by weight is preferred, and a range from 0.04% to 0.5% by weight is particularly preferred. The photographic resin-coated paper in the present invention is a paper or a synthetic paper base (hereinafter simply referred to as base paper) that normally runs.
It is manufactured by melt-extruding a resin composition containing a heated and melted titanium dioxide pigment onto the film through a slit die. When the resin is a polyolefin resin, the melt extrusion temperature is preferably 200°C to 350°C. Further, before coating the resin composition on the base paper, it is preferable to subject the base paper to an activation treatment such as a corona discharge treatment or a flame treatment. There is no particular limit to the thickness of the resin layer of resin-coated paper, but it is generally 5.
Extrusion coatings to a thickness of the order of microns to 50 microns are advantageous. In addition, in ordinary resin-coated paper in which both sides of the base paper are coated with resin,
The resin surface containing titanium dioxide pigment has a glossy surface, a matte surface, a silky surface, etc. depending on its use.
The opposite back surface is usually a matte surface, and if necessary, the front surface or both the front and back surfaces can be subjected to activation treatment such as corona discharge treatment or flame treatment. The base paper used in the practice of the present invention may be ordinary natural pulp paper, synthetic fiber, or so-called synthetic paper made by stiffening synthetic resin film.
Natural pulp paper based on wood pulp of softwood pulp, hardwood pulp, softwood hardwood mixed pulp is advantageously used. There is no particular restriction on the thickness of the base paper, but a base paper with good surface smoothness is preferred, and its basis weight is preferably 50 g/m ² to 250 g/m ² . The base paper mainly composed of natural pulp, which is advantageously used in carrying out the present invention, can contain various polymeric compounds and additives. For example, dry paper strength enhancers include cationized starch, cationized polyacrylamide, anionized polyacrylamide, carboxy-modified polyvinyl alcohol, gelatin, etc. Sizing agents include fatty acid salts, rosin derivatives, dialkyl ketene dimer emulsions, petroleum resin emulsions, etc. , ammonium salt of styrene-maleic anhydride copolymer alkyl ester, etc.
Pigments: clay, kaolin, calcium carbonate, barium sulfate, titanium oxide, etc. Wet paper strength agents: melamine resin, urea resin, epoxidized polyamide resin; Fixing agents: polyvalent metal salts such as aluminum sulfate, aluminum chloride, etc. , cationically modified polymers such as cationized starch, PH
As regulators, caustic soda, soda carbonate, hydrochloric acid, etc., as inorganic electrolytes, salt, mirabilite, etc. In addition, dyes, fluorescent brighteners, latex, etc. can be contained in appropriate combinations. The photographic resin-coated paper of the present invention can be provided with various silver halide photographic emulsion layers.
For example, silver chloride, silver bromide, silver chlorobromide, silver iodobromide,
A silver chloroiodobromide emulsion layer can be provided. Also,
A multilayer silver halide photographic constituent layer can be provided by containing a color coupler in the silver halide photographic emulsion layer. As the binder for these silver halide emulsion layers, in addition to ordinary gelatin, hydrophilic polymeric substances such as polyvinylpyrrolidone, polyvinyl alcohol, and polysaccharide sulfate ester compounds can be used. Further, the above-mentioned silver halide emulsion layer can contain various additives. For example, sensitizing dyes include cyanine dyes and merocyanine dyes, chemical sensitizers include water-soluble gold compounds and sulfur compounds, and anti-capri agents or stabilizers include hydroxy-triazolopyrimidine compounds and mercapto-heterocyclic compounds. Hardeners such as formalin, vinyl sulfone compounds, aziridine compounds, coating aids such as benzene sulfonate, sulfosuccinate salts, anti-staining agents, dialkylhydroquinone compounds, etc., development accelerators, etc.
Hydroquinone, phenidone, etc., ultraviolet absorbers, benzotriazole compounds, etc., fluorescent whitening agents, sharpness-improving dyes, antistatic agents, PH
In addition to the regulator, a water-soluble iridium compound, a water-soluble rhodium compound, etc. can be contained in an appropriate combination when the main component and dispersion of silver halide is carried out. Further, on the back side of the photographic resin-coated paper in the present invention, that is, on the support surface opposite to the side on which the photographic constituent layer, often the silver halide photographic constituent layer, is coated, anti-curl, antistatic, A coating layer consisting of a hydrophilic colloid layer called a back coat layer can be provided for the purpose of preventing adhesion and slipping. Such a back coat layer may contain a binder, a protective colloid, a curing agent, an antistatic agent, a surfactant, a matting agent, a latex, and the like. Next, in order to explain the present invention more specifically,
An example will be described. [Example 1] An ultramarine fired product produced by firing a mixture consisting of kaolin, diatomaceous earth, soda ash, sulfur, and a charcoal reducing agent is dry-pulverized, and the crushed product is suspended in water to obtain an ultramarine suspension. It was clarified into a liquid, pre-washed with water using a decantation method, further wet-pulverized in a wet ball mill, and wet-classified using a continuous horizontal centrifuge to produce an ultramarine slurry substantially free of coarse ultramarine particles. Thereafter, the initial mother liquor of the ultramarine slurry was passed through a filter press, and the ultramarine cakes in the filter press were subsequently washed with water under predetermined water washing conditions until ultramarine pigments with electrical conductivities listed below were obtained, respectively. did. Thereafter, the ultramarine cake was dried and further ground in a swing hammer type impact mill with a quantitative feeder, and the electrical conductivity of the suspension as referred to in this specification was 360μ/cm, 260μ/cm, 200μ/cm,
Six types of ultramarine pigments with values of 150 μ/cm, 100 μ/cm, and 50 μ/cm were produced, respectively. The particle sizes of these ultramarine pigments are determined by the light transmission method.
It is in the range of 0.3μ to 1μ. Thus, 70 parts by weight of low density polyethylene (MI=7, density 0.923 g/cm ³ ), 30 parts by weight of titanium dioxide pigment.
parts by weight, 1.0 parts by weight of ultramarine blue pigment and 1.5 parts by weight of zinc stearate at 150°C using a Banbury mixer.
The mixture was thoroughly kneaded to obtain a masterbatch consisting of the six kinds of ultramarine pigments and the titanium dioxide pigment. On the other hand, a mixed stock of 50 parts by weight of hardwood bleached kraft pulp and 50 parts by weight of softwood bleached sulfite pulp was prepared using Canadian Standard, Freeness 310.
ml, and further added to 100 parts by weight of pulp, 3 parts by weight of cationized starch, 0.2 parts by weight of anionized polyacrylamide, 0.4 parts by weight of alkyl ketene dimer emulsion (as ketene dimer content), and 0.4 parts by weight of polyaminopolyamide epichlorohydrin resin. A paper with a basis weight of 160 g/m ² was made.
The obtained wet paper was dried at 110°C, and then 3 parts by weight of carboxy-modified polyvinyl alcohol, 0.05 parts by weight of a fluorescent brightener (Blancophor: manufactured by Bayer AG), and a blue dye (Diamirror Turkish Blue B:
0.002 parts by weight of Mitsubishi Kasei Corporation), ^0.2 parts by weight of citric acid, and 97 parts by weight of water. After the treatment, both sides thereof were subjected to corona discharge treatment to produce a base paper for photographic resin-coated paper. Next, apply high-density polyethylene (density
A 1:1 mixture of 0.96 g/cm ² , MI=5) and low density polyethylene (density 0.92 g/cm ² , MI=5) was coated to a thickness of 30μ using a melt extrusion coater at a resin temperature of 330°C. did. Next, 30 parts by weight of a masterbatch consisting of the ultramarine blue pigment and titanium dioxide pigment described above and high-density polyethylene (density 0.96) were applied to the surface of the base paper.
g/cm ³ , MI=5) and 50 parts by weight of low-density polyethylene (density 0.92 g/cm ³ , MI=5) was coated to a thickness of 30μ at a resin temperature of 330°C. Then, polyethylene resin-coated papers containing ultramarine blue with different suspension electrical conductivities were produced. At that time, the surface of the polyethylene containing ultramarine blue 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 surface of the polyethylene resin-coated paper thus obtained was observed, and the number of ultramarine aggregates generated on the polyethylene resin surface was visually counted. Further, the surface of the polyethylene resin-coated paper containing the ultramarine blue was subjected to a corona discharge treatment, and a silver halide photographic emulsion was coated thereon and developed, after which desensitization and generation of capri were examined. The results obtained are shown in Table 1.

[Example 2]

Example 1 Ultramarine blue was crushed by the following crusher and has a suspension electrical conductivity of 180 μ/cm as referred to in this specification.
It was manufactured in the same manner. (a) Repulsion hammer crusher (for comparison) (b) Centrifugal roller mill (for comparison) (c) Swing hammer impact mill (invention) (d) Steam mill (invention) (e) Swing hammer impact mill Grinding in a mill and then pulverizing in a steam mill (invention) The same procedure as in Example 1 was carried out except that the ultramarine thus obtained was used in place of the ultramarine used in Example 1. The particle diameters of these ultramarine pigments are determined by a light transmission method and are in the range of 0.5μ to 1.5μ for the comparative examples, and in the range of 0.25μ to 1μ for those of the present invention. The results obtained are shown in Table 2.

[Table] From Table 2, it can be seen that the resin-coated paper of the present invention containing ultramarine crushed by an impact mill or/and a fluid energy mill can well prevent the generation of ultramarine aggregates and desensitization fog, and can be used as a support for photographs. It is clear that it is good for the body.

Claims (1)

[Scope of Claims] 1. A photographic resin-coated paper in which the paper support is coated with a polyolefin resin containing ultramarine blue, wherein the ultramarine blue has a particle size determined by a light transmission method by being crushed by an impact mill or/and a fluid energy crusher. 0.2μ~
8μ, and the ultramarine blue has a suspension electrical conductivity defined below of 200μ/cm or less. Suspension electrical conductivity: Place the rotor of a magnetic stirrer in a 100ml beaker and add distilled water.
Add 100ml (water temperature 21.5℃) and continue with 10.0g of ultramarine.
Add. Subsequently, the beaker is placed on the stand of a magnetic stirrer. After that, the conductivity cell (θ = 0.1) of the electrical conductivity meter was placed under the liquid level in the beaker, without touching the rotor, to the extent that the electrical conductivity of the liquid could be measured. Make it possible to track conductivity values. After installation,
Start the magnetic stirrer and turn the rotor to 1.
It rotates at a rotational speed of 420 revolutions per minute to stir the contents in the beaker to form an ultramarine suspension.While maintaining the liquid temperature at 21.5℃±0.5℃,
Stir for a minute. Sixteen minutes after the start of stirring, the electrical conductivity of the ultramarine suspension is read and measured while stirring the suspension at a liquid temperature of 21.5°C. 2. The photographic resin-coated paper according to claim 1, wherein the impact mill is a swing hammer type. 3. The photographic resin-coated paper according to claim 1 or 2, wherein the fluid energy crusher is a steam mill.