JPH0138293B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing a photographic thermoplastic resin composition, and more particularly to a method for producing a photographic thermoplastic resin composition containing extremely little micro grit. The term "microgrit" as used herein refers to minute foreign matter or minute grains that appear on the surface of the coated resin in photographic resin-coated paper in which at least one side of the paper or synthetic paper base is coated with a resin composition. . There are various causes of microgrit, but for example, the formation of microgrit that appears on photographic resin-coated paper manufactured by melt-extruding photographic thermoplastic resin onto at least one side of a paper or synthetic paper substrate using a melt extruder. This is because (1) the thermoplastic resin itself tends to generate a lot of gel, and (2) the temperature cannot be maintained at the appropriate temperature when the molten resin is extruded from the melt extruder through the die into a film. , if the flow is uneven, (3) if the screen attached to the breaker plate in the melt extruder is dirty, (4) if there are cracks in the parel liner in the melt extruder, (5) if the melt Examples include cases where the extruder is insufficiently kneaded, but these can often be resolved relatively easily by skilled engineers. However, the most difficult countermeasure against microgrit is when microgrit occurs in photographic resin-coated paper in which the paper or synthetic paper substrate is coated with a resin composition consisting of at least a thermoplastic resin and a pigment. In the first place, the method of incorporating pigments into a thermoplastic resin, preferably a polyolefin resin, is to prepare a so-called master batch in which pigments are contained in a resin at a high concentration in advance, and then dilute and mix them with a diluent resin to a desired ratio. Ordinarily, a so-called compound is prepared and used, in which a desired composition ratio of pigment is contained in a resin from the beginning. However, when preparing a masterbatch or compound by melt-kneading a thermoplastic resin and a pigment using an ordinary melt-kneading machine such as a Banbury mixer or a kneader, relatively coarse resin particles are present in the thermoplastic resin. However, there is a tendency for pigment particles to be dispersed as they are, rather than being dispersed in a fine state, resulting in the presence of undispersed pigment particles in the masterbatch or compound. As a result, microgrit is deposited on the resin side of a photographic resin-coated paper in which at least one side of the paper or synthetic paper substrate is coated with a resin composition comprising a pigment and a resin produced using the masterbatch or the compound. will occur. The occurrence of microgrit in resin-coated papers used as photographic supports causes serious photographic defects. That is, when a person is photographed on a photographic paper having a resin-coated paper containing microgrit as a photographic support, if microgrit appears in areas such as the face, the photograph has no commercial value. By the way, titanium dioxide pigments are usually used as pigments contained in the resin layer on the emulsion-coated side of resin-coated paper used as photographic supports because they have excellent whiteness, mildness, resolution, etc. This is well known. Resin-coated papers for photography are also already known, for example as disclosed in US Pat. It is well known that the resin layer contains a titanium dioxide pigment, a colored pigment, a fluorescent whitening agent, and the like. Another type of photographic resin-coated paper is a resin composition containing a white pigment such as titanium dioxide, whose paper base is polymerized and cured by electron beam irradiation, as disclosed in JP-A-57-30830. Photographic resin-coated papers coated with are also known. However, for photographic resin-coated paper in which at least one side of the paper or synthetic paper substrate is coated with a resin composition comprising at least a titanium dioxide pigment and a resin, a masterbatch or compound of the titanium dioxide pigment as described above may be used. When manufactured by using the resin-coated photographic paper, as mentioned above, there is a tendency for a large number of microgrits to be generated on the resin surface of the photographic resin-coated paper due to undispersed pigment, that is, titanium dioxide pigment in this case. There was a serious problem. Accordingly, an object of the present invention is to provide a photographic thermoplastic resin-coated paper containing a titanium dioxide pigment in the resin layer and having a good surface quality, in which the generation of microgrit is completely suppressed or not generated at all. . As a result of intensive research by the present inventors, an object of the present invention is to provide a photographic thermoplastic resin composition comprising at least a thermoplastic resin and a titanium dioxide pigment, in which the resin pressure defined in the specification is 20Kg/
It has been found that this can be achieved by applying a photographic thermoplastic resin composition of less than cm ² to photographic thermoplastic coated paper in the form of a so-called masterbatch or compound. The thermoplastic resin composition having a resin pressure of less than 20 kg/cm ² is defined as follows. Resin pressure: Barrel with inner diameter 20mm, length 420mm, 1 pitch 20mm, flight top width 3.1mm, groove depth 3.9mm,
Strand die with 8 pitch feed zone, linear slope, 8 pitch pressure zone, groove depth 1.6 mm, screw consisting of 5 pitch metering zone, breaker plate and resin ejection port with diameter 3 mm and length 20 mm. The temperature of the extruder is set at 180℃, 180℃, 180℃, 180℃ from the resin supply side in an extruder with heating control in four zones, and when the temperature values in all four zones reach 180℃, the carbon dioxide is removed. The same thermoplastic resin used for the titanium-containing thermoplastic resin composition is put into the resin supply port (hopper) on the extruder and melt-extruded at a screw rotation speed of 10 rpm. Next, set the temperature values of the 4 zones to 200℃, 250℃, 320℃, and 320℃ from the hopper side. 4
When all the temperature values in the area reach the set values, attach the Stellence 100 mesh screen and 325 mesh screen to the breaker plate in sequence.
After lowering the screw speed of the extruder to the minimum value,
Install the 325 mesh screen in the extruder with it facing the screw. Thereafter, the screw rotation was increased to 60 rpm, and 500 g of the thermoplastic resin in the hopper was melt-extruded. At this time, the resin pressure in the stable region is defined as AKg/cm ² . Next, 750 g of the titanium dioxide pigment-containing thermoplastic resin composition having a predetermined concentration as described above is collected as a titanium dioxide pigment component, placed in a hopper, and melt-extruded. The value of the highest resin pressure at the time when the thermoplastic resin composition equivalent to 750g as titanium dioxide pigment has finished passing through the extruder outlet is BKg/
Let it be ^cm2 . Here, B-AKg/cm ² is defined as the resin pressure of the thermoplastic resin composition. Specifically, a titanium dioxide pigment is added to a thermoplastic resin using a normal melt-kneading machine such as a Banbury mixer, and thoroughly kneaded to obtain a titanium dioxide pigment-containing thermoplastic resin at a predetermined concentration (wt%). Obtain a composition. Of course, lubricants, stabilizers, antioxidants, colorants, etc. may be added if necessary. The titanium dioxide pigment-containing thermoplastic resin composition thus obtained is tested according to the following procedure. That is, LABO PLASTOMILL manufactured by Toyo Seiki Seisakusho Co., Ltd., model 10-150.
Attach extruder model D-18-20 to
When the temperature values in all four regions reached 180°C, put the same thermoplastic resin used for the titanium dioxide-containing thermoplastic resin composition into the resin supply port (hopper) on the extruder. Screw rotation speed 10rpm
Melt extrude with Next, set the temperature values of the 4 zones to 200℃, 250℃, 320℃, and 320℃ from the hopper side.
When all the temperature values in the 4 regions have reached the set values, attach the stainless steel 100 mesh screen and 325 mesh screen to the breaker plate prepared in advance, and set the screw rotation of the extruder to around the minimum value. Lower it and install it inside the extruder. Thereafter, the screw rotation was increased to 60 rpm, and 500 g of the thermoplastic resin in the hopper was melt-extruded. At this time, the resin pressure in the stable range indicated by the self-recorder is defined as AKg/cm ² . Next, the titanium dioxide pigment-containing thermoplastic resin composition with the above-mentioned predetermined concentration was added as a titanium dioxide pigment component.
A total of 750 g was collected, put into a hopper, and melted and extruded. (Of course, almost all of the thermoplastic resin in the hopper is melt-extruded, and then the titanium dioxide pigment-containing thermoplastic resin composition is added and continuously melt-extruded.) Titanium dioxide The highest resin pressure at the time when the thermoplastic resin composition equivalent to 750 g as a pigment component has finished passing through the extruder outlet is read with a self-recorder, and this value is defined as BKg/cm ² . Here, B-AKg/cm ² is defined as the resin pressure of the thermoplastic resin composition in this specification. In order to produce the photographic thermoplastic resin composition of the present invention, a masterbatch or compound is prepared by mixing the thermoplastic resin and the titanium dioxide pigment using a conventional melt-kneading machine such as a kneader, heated kneading roll, or kneading extruder. However, it is preferable to use a pressure kneader such as a Banbury mixer. The concentration (wt%) of the titanium dioxide pigment relative to the thermoplastic resin in the masterbatch or compound is about 5 to 70%, particularly preferably 5%.
~50%. Of course, as mentioned above, lubricants, stabilizers, antioxidants, colorants, etc. may be added if necessary during kneading. The thermoplastic resin composition thus obtained is 20 kg/kg at the resin pressure defined in the specification.
Those less than cm ² are referred to as photographic thermoplastic resin compositions in the present invention. Up until now, the microgrit in photographic thermoplastic coated paper has usually been expressed in terms of the number of microgrits per gram of the photographic thermoplastic composition used or the number of microgrits per square meter of photographic thermoplastic coated paper. be. As a result of research conducted by the present inventors, it was found that there is a good correlation between the resin pressure and the number of microgrits (number/cm ² ) of the thermoplastic resin composition in the present invention. As a result, by producing photographic thermoplastic resin-coated paper using a photographic thermoplastic resin composition with a resin pressure of less than 20 kg/cm ² , preferably less than 15 kg/cm ² , there is almost no generation of microgrit. Photographic thermoplastic resin-coated paper with good surface quality can be obtained. As described above, the present invention particularly provides photographic thermoplastic resin-coated paper with good surface quality and well-prevented generation of microgrit, which is produced using a masterbatch or compound comprising at least a thermoplastic resin and a titanium dioxide pigment. It is particularly effective for providing photographic polyolefin resin-coated paper. Conventionally, as mentioned above, microgrit has often been measured by visually counting the microgrit appearing on the resin surface of photographic thermoplastic resin-coated paper, but this method requires a great deal of labor and time. However, there was a need for an appropriate measurement method in the field, as there were occasional fluctuations (missing counts, etc.) by the measurer. , such obstacles are also removed,
Since the measurement can be carried out with high precision, it is possible to provide a photographic thermoplastic resin composition of stable quality. The present invention also provides an inorganic surface treatment agent in the resin layer.
In particular, resin-coated paper with titanium dioxide pigment surface-treated with hydrous aluminum oxide or synthetic paper as a substrate, which has excellent light resistance and heat resistance, and has a good surface quality that prevents the generation of microgrit. It is particularly useful for providing photographic thermoplastic coated papers. This is clear from the description below. In the first place, commercially available titanium dioxide pigments contain inorganic surface treatment agents such as hydrated aluminum oxide, hydrated silicon oxide, hydrated titanium oxide, hydrated zirconium oxide, zinc hydroxide, magnesium hydroxide, manganese compounds, phosphoric acid compounds, etc., especially hydrated titanium dioxide pigments. Most of them are modified by precipitation of aluminum oxide and/or hydrous silicon oxide. Thus, the reasons why titanium dioxide pigments are modified by precipitating inorganic surface treatment agents on their particle surfaces are generally to improve the light resistance of titanium dioxide pigments and to improve the dispersibility of titanium dioxide pigments in resins. It was thought that this was for the purpose of As a result of the inventors' investigation, the surface treatment was not performed or the inorganic surface treatment agent was extremely light (the inorganic surface treatment agent was less than 0.2% by weight based on titanium dioxide, calculated as anhydride).
If a titanium dioxide pigment that has only been surface-treated is used in a resin, a serious drawback may arise in that the light resistance and heat resistance of the resin layer containing the titanium dioxide pigment will certainly deteriorate. I understand. This means that even when resin-coated paper containing titanium dioxide pigment in the resin layer is used as a support for photographic paper, serious photographic quality defects such as discoloration of the white background of the photograph and deterioration of the photograph's shelf life occur over time. Leads to. However, as a result of studies conducted by the present inventors, inorganic surface treatment agents, especially hydrated aluminum oxide, were used in an amount of 0.2% by weight based on titanium dioxide, calculated as anhydrous.
When a titanium dioxide pigment that has been surface-treated as described above is used in a resin, the light resistance and heat resistance of the resin-coated paper containing the titanium dioxide pigment in the resin layer are improved, but surprisingly, inorganic Depending on the degree of surface treatment of titanium dioxide pigments with surface treatment agents, especially hydrous aluminum oxide, as the degree increases, the dispersibility of said dioxide pigments in resins, especially thermoplastics, becomes worse and resin-coated paper micro grit tends to occur frequently on the resin surface. Furthermore, if the degree of surface treatment of the titanium dioxide pigment with an inorganic surface treatment agent, especially hydrous aluminum oxide, is 1.2% by weight or more calculated on anhydrous basis with respect to titanium dioxide, the resin of the titanium dioxide pigment,
In particular, the dispersibility in thermoplastic resins becomes extremely poor.
Extremely large amounts of microgrit appear on the resin surface of resin-coated paper. As described above, the titanium dioxide pigment surface-treated with an inorganic surface treatment agent contained in the resin layer of photographic thermoplastic resin-coated paper has a basic pre-protection. That is, in an attempt to improve the light resistance and heat resistance of photographic thermoplastic resin-coated paper, if a highly surface-treated titanium dioxide pigment is included in the resin layer, the generation of microgrit cannot be prevented; In an attempt to prevent this, there was a premonition that if a titanium dioxide pigment that was not surface-treated or that was only lightly surface-treated was included in the resin layer, the light resistance and heat resistance of photographic resin-coated paper would be poor. . Also,
Although it is certain that the generation of microgrits is caused by undispersed particles of titanium dioxide pigment and that the dispersion properties of the titanium dioxide pigment itself in the resin are involved to some extent, the generation of microgrits is due to the undispersed matter of the titanium dioxide pigment. There are many points that cannot be explained by dispersibility alone. What is more important is how and in what respects the dispersibility of titanium dioxide pigments into thermoplastic resins, especially non-polar polyolefin resins, is related to the physical properties of the titanium dioxide pigments themselves. It is not clear at all, and even more so, it is not clear at all how to improve the dispersibility of titanium dioxide pigments into thermoplastic resins, especially polyolefin resins, and the photographic industry is still actively investigating this issue. In the current situation. Thus, it has been extremely difficult to develop a photographic thermoplastic resin-coated paper that is excellent in light resistance and heat resistance, and also has a good surface quality that prevents the generation of microgrit. However, the resin pressure according to the present invention is 20Kg/cm ²
By applying the photographic thermoplastic resin composition below to the resin layer of a photographic resin-coated paper, a photographic thermoplastic with excellent light resistance and heat resistance, and a good surface quality in which the generation of microgrit is prevented. We have succeeded in providing resin-coated paper. Preferred titanium dioxide pigments used in photographic thermoplastic resin compositions with a resin pressure of less than 20 kg/cm ² in the present invention are those in which the amount of inorganic surface treatment agent is calculated based on the amount of anhydride relative to titanium dioxide. hand
0.2% to 1.2% by weight, and particularly preferably, the inorganic surface treatment agent is hydrated aluminum oxide and the treatment amount is 0.2% by weight calculated in the form of Al ₂ O ₃ with respect to titanium dioxide. %~1.2wt%
When such a titanium dioxide pigment is applied to the photographic thermoplastic resin composition of the present invention, a photographic composition with particularly excellent light resistance and heat resistance, and a good surface quality with well-prevented generation of microgrits can be obtained. We have discovered a new fact that thermoplastic resin-coated paper can be provided, and have arrived at the present invention. The titanium dioxide pigment used in the practice of the present invention may be any titanium dioxide pigment that has good dispersibility so that a photographic thermoplastic resin composition having a resin pressure of less than 20 kg/cm ² in the present invention can be obtained. That is, those with rutile structure, those with anatase structure,
Further, either the chlorine method or the sulfuric acid method can be used. Regarding their specific manufacturing method, in the case of the chlorine method, titanium dioxide particles are formed by vapor phase oxidative decomposition of titanium tetrachloride at high temperatures, and particles with a rutile structure are generally easily obtained. In the case of the sulfuric acid process, hydrous titanium oxide is formed by hydrolysis of an aqueous titanyl sulfate solution and is calcined to develop its pigmentary properties. In the case of the sulfuric acid method, products with anatase structure and rutile structure can also be obtained, but when trying to produce products with rutile structure, the firing temperature must be set to a higher temperature than in the case of products with anatase structure. A metal compound such as a zinc compound may be coexisting to promote the formation of a rutile structure. The product produced by calcination or oxidation will hereinafter be referred to as titanium dioxide linker. Titanium dioxide linker is manufactured by centrifugal roller mill (mainly Raymond mill)
The pulverized product is suspended in water to form a titanium dioxide slurry, and then subjected to wet pulverization using a ball mill, vibration mill, sand grinder, or the like. Thermal classification is carried out using a continuous horizontal centrifuge and/or passing through a vibrating double deck screen (325 mesh US standard screen) to produce substantially coarse particles, hereinafter referred to as fines. A titanium dioxide slurry without granular titanium dioxide is made. For fines still in slurry form from which coarse particles have been removed, the surface of the titanium dioxide particles is subjected to a reaction with an inorganic surface treatment agent such as hydrous aluminum oxide, hydrous silicon oxide, or hydrous titanium oxide, particularly preferably hydrous aluminum oxide, with a stirrer. The surface is treated in a treatment tank.
After the reaction treatment, the product is filtered using a filter press, dried using a band dryer, and then pulverized using an impact pulverizer. If the titanium dioxide pigment thus obtained has relatively good dispersibility, when it is kneaded into a thermoplastic resin to form a thermoplastic resin composition, it exhibits a resin pressure of less than 20 kg/cm ² as defined in the present invention. However, in most cases, the dispersibility is insufficient. For the titanium dioxide pigment used in the present invention, any pulverizer can be used in the wet pulverization during the above-mentioned process, and several of the same type or several of different types may be combined, but in any case, Thorough wet grinding is desirable. Furthermore, it is desirable to use a fluid energy grinder, preferably a steam mill such as a micronizer, for final grinding after drying the titanium dioxide cake. Therefore, the most preferred embodiment of the present invention is as follows:
The amount of surface treatment with hydrous aluminum oxide is 0.2% by weight or more calculated in the form of Al ₂ O ₃ based on titanium dioxide.
A thermoplastic resin composition in which 1.2% by weight of titanium dioxide pigment is kneaded into a thermoplastic resin by sufficiently wet grinding during the titanium dioxide manufacturing process and using a steam mill as a finishing grinder. This is a photographic thermoplastic resin composition having a resin pressure of 20 kg/cm ² or less as used in the present invention. The titanium dioxide pigments used in the practice of the invention are advantageously surface-treated with inorganic surface treatment agents, especially hydrous aluminum oxide. Moreover, those that have been surface-treated by a conventionally known method are advantageously used. For example, by adding a water-soluble aluminum salt and/or one or more other water-soluble metal salts and/or optionally a water-soluble silicon compound to a titanium dioxide slurry, preferably fines, and subsequently changing the PH in the slurry. , a titanium dioxide pigment surface-treated by precipitating a poorly soluble oxide hydrate and/or a hardly soluble metal compound can be used. In particular, an aluminate such as an alkali aluminate is used as the water-soluble aluminum salt, and if necessary, the aluminate is slurry which exhibits an alkaline reaction after adding a water-soluble alkali such as caustic soda or potassium hydroxide. In order to reduce the pH value and precipitate hydrated aluminum oxide, it is useful to use a surface treated material by adding a strong acid such as sulfuric acid or hydrochloric acid or a salt exhibiting an acidic reaction. In this case, among alkali aluminates, sodium aluminate is particularly useful. Further, in addition to the aluminate, those whose surface has been treated with an inorganic surface treating agent other than the aluminate or those whose surface has been surface treated with an inorganic surface treating agent other than the aluminate can also be used. In this case, an inorganic surface treatment agent other than the aluminate may be added at any stage of the surface treatment. especially,
If other inorganic surface treatment agents are used in addition to the aluminate, they can be added at any stage before, during, or after the addition of the aluminate. Those added before the addition of the aluminate are useful. Inorganic surface treatment agents other than aluminate used for these surface treatments include silicon compounds such as alkali silicates and silicon tetrachloride, titanium compounds such as titanium tetrachloride, and zirconium, zinc, magnesium, manganese, etc. Various compounds such as metal compounds and phosphoric acid compounds can be used. Resins used in the practice of the invention include polyolefins, polystyrene, polyvinyl chloride, polyacrylic esters, linear polyesters such as polyethylene terephthalate, polycarbonates, polyamides such as nylon, polyacrylonitrile, homopolymers or copolymers such as ethylene - Any resin may be used as long as it is capable of coating a resin film on the base paper, such as vinyl acetate copolymer and mixtures thereof, but thermoplastic resins such as polyolefin, polystyrene, polyethylene terephthalate, and polyvinyl chloride are particularly preferred, and among them polyolefin The resin is particularly advantageous in terms of extrusion coating properties, good adhesion to the base paper, and cost. The polyolefin resin in the present invention refers to a homopolymer such as low density polyethylene, high density polyethylene, polypropylene, polyptene, polypentene, or a copolymer consisting of two or more olefins such as ethylene-propylene copolymer, and a mixture thereof. , those having various densities and melt viscosity indexes (hereinafter simply referred to as MI) can be used alone or in combination. The content of the titanium dioxide pigment contained in the resin layer of the photographic resin-coated paper containing the photographic thermoplastic resin composition of the present invention is as follows:
If it is less than 5% by weight, the softening power will be insufficient as a photographic support, while if it is more than 40% by weight, fluidity etc. will decrease, which is not preferable, and particularly preferably.
It ranges from 7.5% to 25% by weight. The photographic thermoplastic resin composition of the present invention may contain a fatty acid metal salt. Examples of these fatty acid metal salts include zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, zirconium octylate, sodium valmitate, calcium valmitate, and sodium laurate. In addition, the amount added is 0.01% by weight based on the resin composition containing titanium dioxide.
The range of 5% by weight is preferred. In addition to the titanium dioxide pigment and, if necessary, the fatty acid metal salt, the photographic thermoplastic resin composition of the present invention further contains white pigments such as zinc oxide, talc, and calcium carbonate, stearic acid amide, and arachidic acid. Fatty acid amides such as amides, tetrakis(methylene-3-(3,5-di-tert-
Butyl-4-hydroxy-phenyl)probionate)methane, 2,6-di-tert-butyl-4-
Antioxidants such as methylphenol, coloring pigments such as cobalt blue, navy blue, ultramarine, and cobalt violet, fluorescent whitening agents, and the like may be added. The photographic resin-coated paper containing the photographic thermoplastic resin composition in the resin layer of the present invention has a paper or synthetic paper base (hereinafter simply referred to as base paper) that is normally run.
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, and the opposite back surface is usually a matte surface, and it can also be used on both the front and back surfaces as necessary. Activation treatments such as corona discharge treatment and flame treatment can be performed. 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. Further, 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 . 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 oxide, etc. Wet paper strength enhancers include melamine resin, urea resin, and epoxidized polyamide resin. Fixing agents include polyvalent metals such as aluminum sulfate and aluminum chloride. salts, cationically modified polymers such as cationized starch, etc., 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 containing the photographic thermoplastic resin composition of the present invention in its resin layer 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 incorporating 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 antifoggants or stabilizers include hydroxy-triazolopyrimidine compounds and mercapto heterocyclic compounds. , hardeners such as formalin, vinyl sulfone compounds, and aziridine compounds; coating aids such as benzene sulfonate and sulfosuccinate salts; anti-staining agents; dialkylhydroquinone compounds; development accelerators;
Hydroquinone, phenidone, etc., as ultraviolet absorbers, benzotriazole compounds, etc., as well as fluorescent whitening agents, sharpness-improving dyes, antistatic agents, PH regulators, and water-soluble iridium compounds and water-soluble iridium compounds during the production and dispersion of silver halide. Rhodium compounds and the like can be contained in appropriate combinations. Further, the back side of the photographic resin-coated paper containing the photographic thermoplastic resin composition in the resin layer of the present invention is the surface on which the photographic constituent layer, often the silver halide photographic constituent layer, is coated. On the opposite side of the support, a coating layer consisting of a hydrophilic colloid layer called a back coat layer can be provided for the purpose of preventing curling, preventing static electricity, preventing adhesion, preventing slipping, and the like. 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 Anatase-type titanium dioxide linker produced by the sulfuric acid method was dry-pulverized using a centrifugal roller mill, and the pulverized product was suspended in water in the presence of sodium hydroxide to form a titanium dioxide slurry, and two machines were arranged in series. Wet grinding through a sand grinder,
Wet classification was performed using a continuous horizontal centrifuge to produce approximately 25% by weight titanium dioxide substantially free of coarse titanium dioxide. Then, after raising the pH of the slurry to about 9.2 with sodium hydroxide and heating the temperature of the slurry to about 70 °C, calculated in the form of Al ₂ O ₃ with respect to titanium dioxide on a dry basis,
0, 0.15, 0.25, 0.75, 1.0, 1.25, 2.0% by weight, respectively
A 50% by weight aqueous solution of sodium aluminate was added to each solution (excluding 0%) and held for 30 minutes.
Next, 20% by weight sulfuric acid was added to each slurry (except for 0), the pH was lowered to 7.0, and the slurry was further aged for 2 hours. After aging, the titanium dioxide slurries without surface treatment and with surface treatment with hydrous aluminum oxide were passed through a filter press, and the titanium dioxide cakes in the filter press were subsequently washed with running water. Thereafter, the titanium dioxide cake was dried and further pulverized by passing superheated steam at about 250° C. using a steam mill equipped with a metering feeder to produce a total of 8 types of titanium dioxide pigments. Regarding the eight types of titanium dioxide pigments obtained in this way, low density polyethylene (MI=4, density
0.923), 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 master batches of the above eight types of titanium dioxide pigments. The resin pressure of each of the eight masterbatches thus obtained was measured according to the method described in the definition section above. The results obtained are shown in Table 1. On the other hand, a mixed stock of 50 parts by weight of hardwood bleached kraft valve and 50 parts by weight of softwood bleached sulfite valve was mixed with Canadian Standard Freeness 310.
ml, and further added 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 polyaminopolyamide shrimp chlorohydrin per 100 parts by weight of valve. 0.4 parts by weight of resin was added to form paper with a basis weight of 160 g/m ² . The obtained wet paper was dried at 110°C, and then added with 3 parts by weight of carboxy-modified polyvinyl alcohol, 0.05 parts by weight of fluorescent brightener, 0.002 parts by weight of blue dye, and citric acid.
25g of impregnating solution consisting of 0.2 parts by weight and 97 parts by weight of water
Impregnated with ^m2 , dried with hot air at 110℃, and further linear pressure 90
After supercalendering at Kg/cm, both sides 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 heated to resin temperature.
Coatings were made to a thickness of 30μ using a melt extrusion coater at 330°C. Next, 30 parts by weight of the masterbatch of the titanium dioxide pigment described above and high-density polyethylene (density 0.96 g/cm ³ , MI=5) were applied to the surface of the base paper.
Parts by weight and low density polyethylene (density 0.92g/cm ³ ,
A resin composition containing 40 parts by weight of MI=5) was coated to a thickness of 30 μm at a resin temperature of 330° C. to produce polyethylene resin-coated paper containing a titanium dioxide pigment. At that time, the surface of the polyethylene containing the 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 appearing on the glossy resin surface of the polyethylene resin-coated paper containing the photographic thermoplastic resin composition thus obtained was visually counted. The results obtained are shown in Table 1. In addition, among the descriptions in the table, the light resistance of the polyethylene resin-coated paper was tested as follows. A feed meter (FAL-25X-HCL model) manufactured by Suga Test Instruments was applied to the resin surface containing titanium dioxide pigment of resin-coated paper.
After that, the yellow density (hereinafter abbreviated as Y density) on the irradiated surface of the sample was measured using a Macbeth densitometer (TD).
-504 type). The larger the number, the higher the Y concentration, and the higher the Y concentration, the worse the light resistance of the sample.

[Table] It can be seen from Table 1 that as the amount of surface treatment of titanium dioxide with hydrous aluminum oxide increases, the resin pressure increases and the number of microgrits also increases. That is, when the resin pressure is 24 kg/cm ² or more (sample numbers 7 and 8), the number of microgrits increases, while when the surface treatment amount is 0.15% or less (sample numbers 1 and 2), the light resistance becomes significantly worse. I understand. Therefore, the resin pressure of the photographic thermoplastic resin composition in the present invention is less than 20 kg/cm ² and the surface treatment amount of the titanium dioxide pigment used therein is 0.2% by weight or more in the resin layer. If applied, it is possible to obtain photographic polyethylene resin-coated paper with extremely low microgrit. Example 2 A dry pigment obtained in the same manner as in Example 1 by further adding a sodium silicate aqueous solution to the titanium dioxide slurry before adding the sodium aluminate aqueous solution to the titanium dioxide slurry instead of the titanium dioxide pigment used in Example 1. Using titanium dioxide pigments surface-treated with 0.5% by weight of hydrated aluminum oxide calculated in the form of Al ₂ O ₃ and 0.25% by weight of hydrated silicon oxide calculated in the form of SiO ₂ relative to the standard titanium dioxide. A polyethylene resin-coated paper containing a photographic thermoplastic resin composition was manufactured and tested in the same manner as in Example 1, except that the photographic thermoplastic resin composition was used. As a result, this resin-coated paper was found to be suitable as a photographic support because the generation of microgrit was significantly prevented and the paper had excellent light resistance and heat resistance. Example 3 Instead of the resin composition containing titanium dioxide used in Example 1 to coat the surface of the base paper, 30 parts by weight of the same titanium dioxide pigment masterbatch as in Example 1, ethylene-propylene copolymer (propylene Content 0.1% by weight, density 0.945g/cm ² , MI=7) 30 parts by weight and low density polyethylene (density 0.92g/cm ² ,
The same procedure as in Example 1 was carried out except that a resin composition having a composition of 40 parts by weight (MI=7) was used. As a result, the same results as in Example 1 were obtained.

Claims (1)

[Claims] 1. A photograph characterized in that the resin pressure defined below is less than 20 kg/cm ² in producing a photographic thermoplastic resin composition comprising at least a thermoplastic resin and a titanium dioxide pigment. A method for producing a thermoplastic resin composition for use. Resin pressure: Barrel with inner diameter 20mm, length 420mm, 1 pitch 20mm, flight top width 3.1mm, groove depth 3.9mm,
From a screw consisting of an 8-pitch feed zone, a linear slope, an 8-pitch pressure zone, a groove depth of 1.6 mm, and a 5-pitch metering zone, and a strand die with a breaker plate and a resin ejection port with a diameter of 3 mm and a length of 20 mm. In an extruder with heating control consisting of four zones, the temperature of the extruder is set at 180℃, 180℃, 180℃, 180℃ from the resin supply side, and when the temperature values in all four zones reach 180℃, the carbon dioxide is removed. The same thermoplastic resin used for the titanium-containing thermoplastic resin composition is put into the resin supply port (hopper) on the extruder and melt-extruded at a screw rotation speed of 100 rpm. Next, set the temperature values of the 4 zones to 200℃, 250℃, 320℃, and 320℃ from the hopper side. 4
Once all temperature values in the area have reached the set values, attach stainless steel 100 mesh screens and 325 mesh screens to the breaker plate in sequence.
After lowering the screw speed of the extruder to the minimum value,
Install the 325 mesh screen in the extruder with it facing the screw. Thereafter, the screw rotation was increased to 60 rpm, and 500 g of the thermoplastic resin in the hopper was melt-extruded. At this time, the resin pressure in the stable region is defined as AKg/cm ² . Next, the titanium dioxide pigment-containing thermoplastic resin composition with the above-mentioned predetermined concentration was added as a titanium dioxide pigment component.
Collect 750g, put it in a hopper, and melt-extrude it. As titanium dioxide pigment
The maximum resin pressure value at the time when 750g of thermoplastic resin composition has finished passing through the extruder outlet is BKg/cm ²
shall be. Here, B-AKg/cm ² is defined as the resin pressure of the thermoplastic resin composition. 2. The method for producing a photographic thermoplastic resin composition according to claim 1, wherein the titanium dioxide pigment is surface-treated with an inorganic surface treatment agent. 3. The method for producing a photographic thermoplastic resin composition according to claim 2, wherein the inorganic surface treatment agent is hydrated aluminum oxide. 4. The method for producing a photographic thermoplastic resin composition according to claim 2, wherein the inorganic surface treatment agent comprises hydrous aluminum oxide and an inorganic surface treatment agent other than hydrous aluminum oxide. 5. The photographic thermoplastic resin composition according to claim 2, wherein the treatment amount of the inorganic surface treatment agent is 0.2% to 1.2% by weight (calculated in anhydrous form) based on titanium dioxide. manufacturing method. 6. Photographic heat according to claim 3 or 4, wherein the amount of hydrous aluminum oxide treated is 0.2% to 1.2% by weight (calculated in the form of Al ₂ O ₃ ) based on titanium dioxide. A method for producing a plastic resin composition. 7 Claims 1, 2, 3, and 4, in which the thermoplastic resin is a polyolefin resin,
A method for producing a photographic thermoplastic resin composition according to item 5 or 6. 8. The method for producing a photographic thermoplastic resin composition according to claim 7, wherein the polyolefin resin is a polyethylene resin. 9. The method for producing a photographic thermoplastic resin composition according to claim 1, wherein the titanium dioxide pigment is pulverized using a fluid energy pulverizer. 10. The method for producing a photographic thermoplastic resin composition according to claim 9, wherein the fluid energy pulverizer is a steel mill. 11. The method for producing a photographic thermoplastic resin composition according to claim 1, wherein the resin composition contains a fatty acid metal salt.