JPH042174B2 - - 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 inorganic coloring pigments. 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 dioxide, zinc oxide, and talc in order to provide high reflectance and hiding power. It was common to include colored pigments such as blue, magenta or violet to give a visually white appearance (sometimes referred to as blueing). 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.
Methods of adding surfactants such as metal soaps such as magnesium stearate and zinc palmitate, and fatty acid amides such as stearic acid amide and arachidic acid amide are known. However, even when these methods were used, although the ultramarine blue aggregates were slightly reduced, they were still not to a satisfactory degree. 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, the object of the present invention is to provide a photographic resin-coated paper in which the paper support is coated with a polyolefin resin containing ultramarine, in which the ultramarine blue is surface-treated with silica or with a zinc compound. It has been found that this can be achieved by incorporating it into the resin layer. 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 Furthermore, the photographic resin-coated paper of the present invention exhibits little fogging or desensitization, especially when coated with a black-and-white 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, purple-blue, purple, magenta, and deep-colored ultramarine that has been surface-treated with silica or a zinc compound. Any type of color can be used, such as white color, medium color color, light color color, and even a combination of two or more of these. The ultramarine in the present invention may be obtained by subjecting the commercially available ultramarine itself to silica surface treatment or surface treatment with a zinc compound. It's advantageous. In other words, in terms of the production method, a raw material composition containing kaolin, soda carbonate, sulfur, a carbonaceous reducing agent, and, if necessary, silicic acid in the case of producing ultramarine having a magenta color as a color component, is mixed. Shattered. 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 calcined product is washed with water and further wet-milled by a wet ball mill or vibration mill, using a continuous horizontal centrifuge or/and a vibrating double deck screen (e.g. 325 mesh US, 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 belt dryer, and then pulverized with a pulverizer to produce products. However,
It is advantageous for the ultramarine blue in the present invention to be surface-treated with silica after wet classification during the above manufacturing process. Its treatment amount, calculated in the form of _SiO2 , is usually 0.2-20% by weight, preferably 0.5-20% by weight, based on the ultramarine amount. If the amount is less than 0.2% by weight, the covering power of silica against ultramarine blue will not be sufficient and no effect can be expected, while if it exceeds 20% by weight, the pigment concentration will be unnecessarily reduced, which is not preferable. In the subsequent process, according to the above manufacturing process, it is passed through a filter such as a centrifugal dehydrator, dried with a dryer such as a belt dryer, and further pulverized using an impact mill or a fluid energy pulverizer. Manufactured by 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. Air mills and steam mills, which are types of pulverizers that perform pulverization through collisions between particles and between particles and walls, can be used, but steam mills that use the energy of superheated steam prevent the generation of ultramarine aggregates. From this point of view, it is particularly advantageous. Furthermore, in order to exhibit the effects of the present invention even more markedly, it is preferable to use an impact mill and a fluid energy crusher in combination. Further, the surface treatment of ultramarine blue with a zinc compound is carried out as follows. That is, ordinary ultramarine powder is dispersed in an aqueous medium, and one or more zinc compounds such as zinc chloride, zinc hydroxide, zinc oxide, zinc sulfate, zinc nitrate, zinc acetate, zinc citrate, etc. are mixed. Treat it with something. A typical aqueous medium is water, but an appropriate amount of another aqueous solvent such as methyl alcohol, ethyl alcohol, acetone, etc. may be added thereto as appropriate. Normally, about 1 to ultramarine
Add 10 times the amount, preferably about 4 to 6 times the amount of aqueous medium and stir well to uniformly disperse the mixture into a slurry. At this time, dispersion can be promoted by adding a dispersant or using ultrasonic waves. A zinc compound is gradually added to the uniformly dispersed slurry in the form of a solid or an aqueous solution while stirring well. The surface treatment amount of zinc compound for ultramarine is 0.2 to 10% by weight as zinc, preferably 0.5 to 10% by weight.
It is 10% by weight. If the amount is less than 0.2% by weight, the coating power of zinc on the ultramarine blue will not be sufficient and the effect cannot be expected, while if it exceeds 10% by weight, the pigment concentration will be undesirably reduced. The ultramarine surface treated with zinc in this way may be simply dried and then finished, but it is best to bake it at about 110 to 250°C, preferably about 200°C for 0.5 to 24 hours, particularly preferably about 3 to 7 hours. It is particularly effective against desensitization fog. The subsequent pulverization and finishing are performed by an impact mill, a fluid energy pulverizer, or a combination thereof, as in the case of ultramarine treated with silica. Polyolefin resins used in the practice of the present invention include homopolymers such as low-density polyethylene, high-density polyethylene, polypropylene, polybutene, 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 (hereinafter simply referred to as MI) that can be used alone or in combination. In addition to white pigments such as titanium dioxide, 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 dioxide added to the resin layer on the side of the resin-coated paper on which the photographic emulsion layer is coated is preferably in the range of 5% to 20% by weight based on the resin layer. Further, the amount of ultramarine added to the resin layer in combination with a white pigment such as titanium dioxide is preferably in the range of 0.01% to 1.0% by weight based on the resin layer, particularly
A range of 0.04% to 0.5% by weight is 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 a film through a slit die. When the resin is a polyolefin resin, the melt extrusion temperature is preferably 200°C to 350°C. Furthermore, 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 the front surface or both the front and back surfaces can be subjected to activation treatment such as corona discharge treatment or flame treatment if necessary. 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 from 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 include clay, kaolin, calcium carbonate, barium sulfate, titanium dioxide, etc. Wet paper strength agents include melamine resin, urea resin, epoxidized polyamide resin, and fixing agents include polyvalent metal salts such as aluminum sulfate and aluminum chloride. , cationically modified polymers such as cationized starch, etc.
As a pH regulator, caustic soda, soda carbonate, hydrochloric acid, etc., as an inorganic electrolyte, common salt, mirabilite, etc. In addition, dyes, fluorescent whitening agents, 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. In the present invention, especially when a black and white silver halide photographic emulsion is coated, there is little fogging or desensitization, making it extremely suitable for silver halide photographic printing paper. 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, in most cases the silver halide photographic constituent layer, is coated, anti-curl, antistatic, etc. 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. This was preliminarily washed with water using a decantation method, wet-pulverized using 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 ultramarine slurry was placed in a surface treatment tank, and sodium silicate was added to the ultramarine on a dry basis in an amount of 0.2, 0.5, 2.0, 5.0, 10, 20, and 40% by weight, calculated in the form of _SiO2 . Seven kinds of ultramarine slurries each having been subjected to silica surface treatment with an aqueous solution were obtained. Each of these was passed through a filter press and washed with water, and the ultramarine wet cake was dried using a belt dryer, and then ground using a swing hammer impact mill with a quantitative feeder. Obtained. (Samples Nos. 1 to 7) Next, apart from this, ultramarine blue pigments were obtained by the same procedure as that for the silica surface treatment described above, except that the silica surface treatment was not performed. (Sample No. 8) Thus, 70 parts by weight of low density polyethylene (MI = 7, density 0.92 g/cm ³ ), 30 parts by weight of titanium dioxide pigment, 1.0 parts by weight of ultramarine pigment and 1.5 parts by weight of zinc stearate were mixed in a Banbury mixer. The mixture was thoroughly kneaded at 150° C. to obtain masterbatches each consisting of the eight kinds of ultramarine pigments and titanium dioxide pigment. On the other hand, a mixed stock of 50 parts by weight of bleached hardwood kraft pulp and 50 parts by weight of bleached softwood 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 paper was dried at 110°C and then impregnated with an impregnating solution consisting of 3 parts by weight of carboxy-modified polyvinyl alcohol, 0.05 parts by weight of a fluorescent brightener, 0.002 parts by weight of blue dye, 0.2 parts by weight of citric acid and 97 parts by weight of water. 25
After impregnating the paper with g/m ² , drying with hot air at 110°C, and calendering at a linear pressure of 90 kg/cm, both sides of the paper 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 ³ , MI=5) and low density polyethylene (density 0.92 g/cm ³ , 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 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 amounts of silica surface treatment 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 for black and white was coated thereon and developed, after which desensitization and occurrence of fog were examined. The results obtained are shown in Table 1.

[Table] From Table 1, it can be seen that in the resin-coated paper containing ultramarine (sample No. 8) without silica surface treatment in the polyethylene resin layer, many ultramarine aggregates were generated, and desensitization fog occurred. It was completely unsuitable for use as a photographic resin-coated paper. On the other hand, ultramarine (sample No. 1 to
Resin-coated papers containing ultramarine blue aggregates and desensitization fog were well prevented in the resin-coated papers containing ultramarine blue (Samples No. 2 to No. 7) with a silica surface treatment amount of 0.5 to 40% by weight.
7), the generation of ultramarine agglomerates and desensitization fog are better prevented, and it is found that this is preferable as a photographic resin-coated paper. However, the resin-coated paper containing ultramarine blue (sample No. 7) with a silica surface treatment amount of 40% by weight had a poor bluing effect, and could only have a poor appearance as a photographic resin-coated paper. Example 2 Regarding the ultramarine blue of Example 1, Samples No. 2 and No. 8,
The experiment was carried out in the same manner as in Example 1, except that the ultramarine blue obtained by pulverizing with each of the crushers listed in Table 2, note 2 was used instead of the ultramarine blue used in Example 1. The results obtained are shown in Table 2.

[Table] From Table 2, as can be seen from Example 1, the resin-coated paper with a silica surface treatment amount of 0.5% by weight and containing ultramarine crushed by an impact mill has the following properties:
Although it is suitable as resin-coated paper for photography, resin-coated paper containing ultramarine that is produced by using a steam mill instead of an impact mill, or a combination of an impact mill and a steam mill, may also cause ultramarine aggregates and desensitization. It can be seen that this is even better prevented. On the other hand, ultramarine that has not been subjected to silica surface treatment and has been milled using an impact mill may be desensitized, although the number of ultramarine aggregates will be reduced even if a steam mill or a combination of an impact mill and a steam mill are used. On the contrary, the fogging tended to increase, indicating that the paper was unsuitable as a photographic resin-coated paper. Example 3 Ultramarine powder was added to a surface treatment tank filled with water in advance and stirred well to form an ultramarine slurry.
Six kinds of pigment slurries each having been subjected to zinc surface treatment with an aqueous zinc chloride solution to a concentration of 10 and 20% by weight were obtained. Incidentally, the subsequent steps were carried out in the same manner as in Example 1. However, for the ultramarine blue (sample No. 17) that was not subjected to surface treatment, the ultramarine blue powder was used as it was. The results obtained are shown in Table 3.

[Example 4]

Regarding the ultramarine of Example 3, Samples No. 12 and No. 17,
The experiment was carried out in the same manner as in Example 3, except that the ultramarine blue obtained by crushing with each of the crushers described in Table 4, Note 4 was used instead of the ultramarine blue used in Example 3. The results obtained are shown in Table 4.

【table】

[Table] From Table 4, it can be seen from Example 3 that the resin-coated paper with a zinc surface treatment amount of 0.5% by weight and containing ultramarine crushed by an impact mill had the following properties:
Although it is suitable as resin-coated paper for photography, resin-coated paper containing ultramarine that is produced by using a steam mill instead of an impact mill, or a combination of an impact mill and a steam mill, may also cause ultramarine aggregates and desensitization. It can be seen that this is even better prevented. On the other hand, if the ultramarine is not subjected to zinc surface treatment and is ground using an impact mill, the number of ultramarine aggregates will be reduced even if a steam mill or a combination of an impact mill and a steam mill are used. The paper fog showed a tendency to increase, and it was found that the paper was unsuitable as a photographic resin-coated paper.

Claims (1)

[Claims] 1. A photographic resin-coated paper in which a paper support is coated with a polyolefin resin containing ultramarine blue, characterized in that the ultramarine blue has been surface-treated with silica or a zinc compound.