JPS59164550A - Manufacture of thermoplastic resin composition for photography - Google Patents

Abstract

PURPOSE:To obtain the titled composition having superior light and heat resistances and giving resin coated paper for photography almost free from microgrit by kneading a surface-treated titanium dioxide pigment with a thermoplastic resin after carrying out finish grinding by means of a steam mill. CONSTITUTION:The surface of a titanium dioxide pigment is treated with an inorg. surface treating agent such as aluminum oxide hydrate. The treating agent is used by 0.2-1.2wt% of the amount of the pigement when expressed in terms of anhydride. The surface-treated pigment is subjected to finish grinding by means of a fluid energy grinder such as a steam mill. The resulting titanium dioxide pigement is kneaded with a thermoplastic resin such as polyethylene resin under melting by means of a Banbury's mixer or the like to obtain a thermoplastic resin composition for photography having <20kg/cm<2> resin pressure. The resin pressure is defined as the difference between the maximum resin pressure during the extrusion of the resin composition from an extruder and the resin pressure in the stable range during the extrusion of only the resin.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a photographic thermoplastic resin composition.
The present invention relates to a method for producing a photographic thermoplastic resin composition having extremely low grit.

The term "microgrit" as used herein refers to microscopic foreign matter or microscopic particles 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 types of semi-solid microgrit, but for example, microgrit that appears in 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. As a semi-solid, (1)
If the thermoplastic resin used itself generates a lot of gel, (2) When the molten resin is extruded from the melt extruder through the die into a film, the temperature cannot be maintained at the appropriate temperature, resulting in uneven flow. (3) If the screen attached to the breaker plate in the melt extruder is dirty, (4) If there are cracks in the barrel liner in the melt extruder, (5) If the melt extruder is bent. There may be cases of shortages, 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 masterbatch 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 a normal melt mixing machine such as a Banbury mixer or a kneader, relatively coarse particles may be present in the thermoplastic resin. There is a tendency for pigment particles to be dispersed as they are without being dispersed in a fine state, thus resulting in the presence of undispersed pigment particles in the masterbatch or compound.

As a result, 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. Microgrit will be generated.

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 microgrit-generated resin-coated paper as a photographic support, if microgrit appears in areas such as the face, the photograph has no commercial value.

Incidentally, 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, mild resolution, and other properties. This is well known.

Furthermore, resin-coated paper for photographs is already known.
For example, as disclosed in U.S. Pat. No. 3,501,298, both sides of a paper substrate are coated with a polyolefin resin, particularly a polyethylene resin, and the polyolefin resin layer on the emulsion-coated side is coated with titanium dioxide pigments, colored pigments, Products containing fluorescent brighteners and the like are well known. Another type of photographic resin-coated paper is JP-A-57-30830.
Photographic resin-coated papers are also known in which a paper substrate is coated with a resin composition containing a white pigment, such as titanium dioxide, which is polymerized and cured by electron beam irradiation, as disclosed in No. 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 titanium dioxide pigment masterbatch or a titanium dioxide pigment masterbatch as described above may be used. When manufactured using a compound, microgrits due to undispersed pigments, in this case titanium dioxide pigments, tend to occur frequently on the resin surface of the photographic resin-coated paper, as described above. There was a serious problem that there was a trend.

Therefore, an object of the present invention is to provide a photographic thermoplastic resin-coated paper containing 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, the purpose of the present invention is to:
In producing a photographic thermoplastic resin composition comprising at least a thermoplastic resin and a titanium dioxide pigment, the photographic thermoplastic resin composition having a resin pressure of less than 2 oV as defined in the specification is used as a so-called masterbatch. Alternatively, it has been found that this can be achieved by application in the form of a compound to photographic thermoplastic coated paper.

The thermoplastic resin composition having a resin pressure of less than 20 kg/- is defined as follows.

Add titanium dioxide pigment to the thermoplastic resin using a normal melt mixer, such as a Banbury mixer, and mix thoroughly to obtain a titanium dioxide pigment-containing thermoplastic resin composition at a predetermined concentration (wt%). . Of course, if necessary, lubricant,
Stabilizers, antioxidants, colorants, etc. may also be added.

The titanium dioxide pigment-containing thermoplastic resin composition thus obtained is tested according to the following procedure. That is, Laboplastomill (LABO-P manufactured by Toyo Seiki Seisakusho Co., Ltd.)
LASTOM engineering L1. 18011. , 180℃, 180℃, 180℃
When the temperature values in all four regions reached 180°C, the same thermoplastic resin used for the titanium dioxide-containing thermoplastic resin composition was put into the resin supply port (hopper) on the extruder. Melt extrusion is carried out at a screw rotation speed of 10 rpm.

Next, set the temperature values in the 4th region to 200℃ and 250℃ from the hopper side.
, 320°C, and 320°C.

Once the temperature values in all four regions have reached the set values, attach the stainless steel 100 mesh screen and 325 mesh screen to the prepared plate in sequence, and set the extruder screw rotation to the lowest value. and then install it into the extruder. After that, screw rotation e6
Increase the speed to 0 rpm and melt extrude 500 g of thermoplastic resin in the hopper. At this time, the resin pressure in the stable range indicated by the self-recorder is defined as AK9/A.

Next, the titanium dioxide pigment-containing thermoplastic resin composition having a predetermined concentration is sampled so that the titanium dioxide pigment content is 750f, placed in a hopper, and melt-extruded. (Of course, almost all of the thermoplastic resin in the hopper will be melt-extruded, and then the titanium dioxide pigment-containing thermoplastic resin composition will be added and continuously melt-extruded).

The highest resin pressure at the time when a thermoplastic resin composition equivalent to 750 mm as a titanium dioxide pigment portion has finished passing through the extruder outlet is read on a recorder, and this value is defined as BKp/V.

Here, B-AKg/ad 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, the thermoplastic resin and the titanium dioxide pigment are mixed in a conventional melt mixing machine, such as a kneader 1 heated drawing roll, a mixing extruder, etc., and a master batch or Although a compound may be prepared, it is preferable to use a pressure kneader such as a Banbury mixer. Concentration of titanium dioxide pigment to thermoplastic resin in masterbatch or compound (
weight%) is about 5 to 70%, particularly preferably 5 to 50%.
%. Of course, as mentioned above, lubricants, stabilizers, antioxidants, colorants, etc. may be added if necessary at the time of crosstalk. A thermoplastic resin composition thus obtained having a resin pressure of less than 20 degrees as defined in the specification is referred to as a photographic thermoplastic resin composition in the present invention.

Traditionally, the microgrit of photographic thermoplastic coated papers has been expressed as the number of microgrits per gram of the photographic thermoplastic composition used therein or the number of microgrits per square meter of photographic thermoplastic coated paper. is normal. 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/cr) of the thermoplastic resin composition in the present invention. As a result, the resin pressure is preferably less than 20 Ky/k By producing photographic thermoplastic resin-coated paper using a photographic thermoplastic resin composition having an i sKy/cr of less than 1, a photographic thermoplastic resin-coated paper with good surface quality and almost no generation of microgrit can be obtained. You can get it.

Thus, the present invention particularly provides a photographic thermoplastic resin having good surface quality and well-prevented from the generation of microgrit, which is produced using a masterbatch or compound comprising at least a thermoplastic resin and a titanium dioxide pigment. It is useful for providing coated papers, especially photographic polyolefin resin coated papers.

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 lot of labor and effort. It takes time, and there is a risk of deviation by the measurer (
Counting errors, etc.) occur from time to time, and an appropriate measurement method has been desired in this field! According to the method of measuring the pressure of photographic thermoplastic resin compositions as in the present invention, such obstacles are removed and measurements can be made with high accuracy, so that photographic thermoplastic resin compositions of stable quality can be obtained. can provide things.

The present invention also provides a resin-coated paper using paper or synthetic paper as a substrate, in which a titanium dioxide pigment whose surface has been treated with an inorganic surface treatment agent, particularly hydrated aluminum oxide, is contained in the resin layer, and which has excellent light resistance and heat resistance. Moreover, it is particularly effective in providing excellent photographic thermoplastic resin-coated paper that prevents the generation of microgrit and has good nine-face quality. 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 712, 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 studies conducted by the present inventors, it was found that the inorganic surface treatment agent has a very low R
If a titanium dioxide pigment that has been surface-treated only for less than Even when resin-coated paper containing titanium dioxide pigment in the resin layer is used as a support for photographic paper, the white background of the photograph changes color over time and the storage stability of the photograph deteriorates. This can lead to serious photo quality defects such as deterioration of the image quality.

However, as a result of studies conducted by the present inventors, titanium dioxide pigments that have been surface-treated with an inorganic surface treatment agent, especially hydrated aluminum oxide, have a concentration of 0.2% by weight or more based on anhydrous titanium dioxide. When used in resin,
Although the light resistance and heat resistance of resin-coated paper containing the titanium dioxide pigment in the resin layer are improved, surprisingly, depending on the degree of surface treatment of the titanium dioxide pigment with an inorganic surface treatment agent, especially hydrous aluminum oxide, As the degree of dispersion increases, the dispersibility of the pigment dioxide into resins, particularly thermoplastic resins becomes poor, and microgrit tends to occur frequently on the resin surface of resin-coated paper. Furthermore, the degree of surface treatment of titanium dioxide pigments with inorganic surface treatment agents, especially hydrated aluminum oxide, is 1 when calculated on anhydrous basis with respect to titanium dioxide.
．． When the concentration is 2% by weight or more, the dispersibility of the titanium dioxide pigment in resins, especially thermoplastic resins, becomes very poor.
Microgrit becomes extremely abundant on the resin surface of resin-coated paper.

As described above, there is a fundamental contradiction in titanium dioxide pigments that are surface-treated with inorganic surface-treating agents that are contained in the resin layer of photographic thermoplastic resin-coated papers. 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 order to prevent this, if a titanium dioxide pigment that has not been surface-treated or has been surface-treated only lightly is included in the resin layer, there is a contradiction that the light resistance and heat resistance of the resin-coated photographic paper are poor. Ta. Furthermore, although it is certain that the generation of microgrit is caused by undispersed particles of titanium dioxide pigment, and therefore the dispersion properties of the titanium dioxide pigment itself in the resin are involved to some extent, the generation of microgrit is There are many points that cannot be explained solely by the dispersibility of titanium dioxide pigments. More importantly, it is unclear in the first place how and how the dispersibility of titanium dioxide pigments into thermoplastic resins, especially non-polar polyolefin resins, is related to the physical properties of titanium dioxide pigments themselves. It is not clear, 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 currently actively investigating this issue. In the current situation. Thus, it has been extremely difficult to develop thermoplastic resin-coated paper for photography that has excellent light resistance and heat resistance, and also has a good surface quality that prevents the generation of microgrit. However, by applying the photographic thermoplastic resin composition according to the present invention with a resin pressure of less than 20 Kq/c4 to the resin layer of photographic resin-coated paper, it is possible to obtain excellent light resistance and heat resistance, and to prevent the generation of microgrit. We succeeded in providing photographic thermoplastic resin-coated paper with good surface quality.

Preferred titanium dioxide pigments used in photographic thermoplastic resin compositions with a resin pressure of less than 20 Ky/i in the present invention have a treatment amount of an inorganic surface treatment agent calculated on an anhydride basis with respect to titanium dioxide. α2% by weight to L2% by weight, and particularly preferably, the inorganic surface treatment agent is hydrated aluminum oxide, and the treatment amount is α2% by weight calculated in the form of At, O, with respect to titanium dioxide. weight%~
When such a titanium dioxide pigment is applied to the photographic thermoplastic resin composition of the present invention,
In particular, we discovered a new fact that it is possible to provide photographic thermoplastic resin-coated paper that has excellent light resistance and heat resistance, prevents the generation of microgrit, and has good nine-sided quality, and has led to the present invention. .

The titanium dioxide pigment used in the practice of the present invention includes:
Any titanium dioxide pigment may be used as long as it has good dispersibility so that a photographic thermoplastic resin composition having a resin pressure of less than 20 yen can be obtained in the present invention. That is, those with rutile structure, those with anatase structure, those produced by chlorine method, and those produced by 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 solution of titanyl sulfate and is calcined to develop its pigmentary properties. In the case of the sulfuric acid method, products with both anatase structure and rutile structure can 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 is allowed to coexist to promote the formation of a rutile structure during firing. The product produced by calcination or oxidation will hereinafter be referred to as titanium dioxide linker. The titanium dioxide tarinker is dry-pulverized using a centrifugal roller mill (mainly a Raymond mill), the pulverized product is suspended in water to form a titanium dioxide slurry, and the titanium dioxide slurry is further subjected to wet-pulverization using a ball mill, vibration mill, sand grinder, or the like. Use a continuous horizontal centrifuge or/and vibrating double deck screen (325
The slurry is passed through a mesh (U, S, standard screen) to perform hot classification, resulting in a titanium dioxide slurry substantially free of coarse particles of titanium dioxide, which is hereinafter referred to as fine (fineθ). For fines still in slurry form from which coarse particles have been removed, the surface of the titanium dioxide particles is treated with an inorganic surface treatment agent such as hydrous aluminum oxide, hydrous silicon oxide, or hydrous titanium oxide, particularly preferably hydrous aluminum oxide, and the surface of the titanium dioxide particles is reacted with a stirrer. The surface is treated in a treatment tank. After the reaction treatment, the product is filtered with a filter press, dried with a band dryer, and then pulverized with an impact pulverizer.

The titanium dioxide pigment thus obtained, which has relatively good dispersibility, can be kneaded into a thermoplastic resin to form a thermoplastic resin composition at a resin pressure of 20 kg/cr as used in the present invention.
Although it may show less than 1, the dispersibility is generally insufficient in many cases.

For the titanium dioxide pigment used in the present invention, any two pulverizers may be used in the wet pulverization during the above-mentioned process, or several of the same type or several of different types may be combined; In any case, it is desirable to carry out sufficient wet grinding. Furthermore, it is desirable to use a fluid energy grinder, preferably a steam mill such as a micronizer, for final grinding of the dried titanium dioxide cake layer.

Therefore, in the most preferred embodiment of the present invention, the amount of surface treatment with hydrous aluminum oxide is 0.2% by weight to L2% by weight calculated in the form of At, O, based on titanium dioxide, and the titanium dioxide manufacturing process A thermoplastic resin composition in which a titanium dioxide pigment produced by sufficiently wet grinding in a thermoplastic resin and a steam mill grinder as a finishing grinder is kneaded into a thermoplastic resin has a resin pressure of 2.
It is a photographic thermoplastic resin composition having oKy/d or less.

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, 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 fine, and subsequently adjusting the pH in the slurry. By changing the formula, it is possible to use a titanium dioxide pigment that has been surface-treated by precipitating a slightly soluble oxide hydrate and/or a slightly soluble metal compound on the titanium dioxide pigment. In particular, as a water-soluble aluminum salt,
For example, using an aluminate such as alkali aluminate, the aluminate can be optionally reduced to a slurry exhibiting an alkaline reaction after adding a water-soluble alkali such as caustic soda, potassium hydroxide, etc., and reducing the pH value. In order to precipitate hydrated aluminum oxide, it is useful to use a material that has been surface-treated by adding a strong acid such as sulfuric acid or hydrochloric acid or a salt that exhibits 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.

In particular, when other inorganic surface treatment agents are used in addition to the aluminate, it can be added at any stage before, during, or after the addition of the aluminate. Particularly useful are those added before the addition of the aluminate. 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 can be used as long as it is possible to coat a resin film on the base paper, such as vinyl acetate copolymer and mixtures thereof, but especially polyolefin,
Thermoplastic resins such as polystyrene, polyethylene terephthalate, and polyvinyl chloride are preferred, and among them, polyolefin resins are particularly advantageous in terms of extrusion coating properties, good adhesion to base paper, and cost. The polyolefin resin in the present invention is a homopolymer such as low density polyethylene, high density polyethylene, polypropylene, polybutene, 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 (melt index: hereinafter simply referred to as "M") 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 5% by weight or less based on the resin, and the photographic support As the calming force is insufficient and reeds, while 4
If it is more than 0% by weight, the fluidity etc. will deteriorate and it is not preferable, and the range of 7.5% to 25% by weight is particularly preferable.

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 balmitate, and sodium laurate. Further, the amount added thereof is preferably in the range of 0.01% by weight to 5% by weight based on the resin composition containing titanium dioxide.

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 alaxinic acid. fatty acid amides such as amides, tetrakis(methylene-3(&5-di-tert-butyl-4-hydroxy-phenyl)propionate)methane, z6-di-tert-butyl-4-
antioxidants such as methyl-phenol; color pigments such as cobalt blue, navy blue, ultramarine, and cobalt violet;
A fluorescent brightener or the like may also be added.

The photographic resin-coated paper containing the photographic thermoplastic resin composition in the resin layer of the present invention is a resin-coated paper containing a titanium dioxide pigment heated and melted on a paper or synthetic paper base (hereinafter simply referred to as base paper) that is normally run. It is manufactured by melt-extruding the composition into a film through a slit die. When the resin is a polyolefin resin, the melt extrusion temperature is 200°C to 350°C.
Preferably it is ℃. 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 fire treatment. There are no particular limitations on the thickness of the resin layer of the resin-coated paper, but it is generally advantageous to extrude coat it to a thickness of about 5 microns to 50 microns. 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 the application, and the opposite side has a glossy surface, a matte surface, a silky surface, etc. The 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 fire treatment.

The base paper used in the practice of the present invention is ordinary natural pulp paper,
Although synthetic fibers or so-called synthetic paper made by bonding synthetic resin films may be used, natural pulp paper whose main component is wood pulp such as softwood pulp, hardwood pulp, or 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'.

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, ammonium salts of styrene-maleic anhydride copolymer alkyl esters, pigments,
Clay, kaolin, calcium carbonate, barium sulfate, titanium oxide, etc., as wet paper strength enhancers, melamine resin,
As urea resin, epoxidized polyamide resin, fixing agent,
Polyvalent metal salts such as aluminum sulfate and aluminum chloride, cationically modified polymers such as cationized starch, etc.
As an H regulator, caustic soda, soda carbonate, hydrochloric acid, etc.
As the inorganic electrolyte, salt, mirabilite, etc., as well as 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, and silver chloroiodobromide emulsion layers can be provided. Furthermore, 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 polyvinipyl I lolidone, 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, etc. Coating aids such as benzene sulfonates, sulfosuccinates, etc. Anti-staining agents such as dialkylhydroquinone compounds, development accelerators such as hydroquinone, UV absorbers such as phenidone, benzotriazole compounds, etc., fluorescent whitening agents, sharpness-enhancing dyes, antistatic agents, pH
In addition to the regulator, a water-soluble iridium compound, a water-soluble rhodium compound, etc. may be contained in appropriate combinations during the production and dispersion of silver halide.

In addition, the back side of the photographic resin-coated paper containing the photographic thermoplastic resin composition in the resin layer of the present invention is opposite to the side on which the photographic constituent layer, often the silver halide photographic constituent layer, is coated. On the side support surface, a coating layer consisting of a hydrophilic colloid layer called a back coat layer can be provided for the purpose of preventing curling, antistatic, adhesion, and smearing.

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

(Example 1) Anatase-type titanium dioxide linker produced by the sulfuric acid method is dry-pulverized in a centrifugal roller mill, and the pulverized product is hydroxylated) Suspended in water in the presence of IJium to form a titanium dioxide slurry, Furthermore, it was wet-pulverized through two sand grinders arranged in series, and wet-classified using a continuous horizontal centrifuge to produce titanium dioxide having a content of approximately 25% by weight, which was substantially free of coarse titanium dioxide. Then, the pH of the slurry was raised to about 9.2 with sodium hydroxide,
After heating the slurry-9 temperature to approximately 70°C, each k
Olo, 15.0.25.0.5.0.75, LOl
1, 25. Add 50% by weight aqueous sodium aluminate solution to 2.0% by weight (excluding 0), 30
Hold for 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, each of the titanium dioxide slurries without surface treatment and with surface treatment with hydrous aluminum oxide was filtered using a filter press, and subsequently, the titanium dioxide cake in the filter press was washed with running water.

Thereafter, the titanium dioxide cake was dried and further pulverized using a steam mill equipped with a quantitative feeder through superheated steam at about 250° C. to produce a total of 8 types of titanium dioxide pigments.

Regarding the 8 types of titanium dioxide pigments obtained in this way, low density polyethylene (M = 4, density α923) 70
150 parts by weight, 30 parts by weight of titanium dioxide pigment and 5 parts by weight of zinc stearate using a Banbury mixer.
The mixture was thoroughly kneaded at 0.degree. C. to obtain masterbatches of the eight types of titanium dioxide pigments described above.

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 paper stock of 50 parts by weight of hardwood bleached kraft pulp and 50 parts by weight of softwood bleached sulfide pulp was beaten to Canadian Standard Freeness 310-, and to 100 parts by weight of pulp, 3 parts by weight of cationized starch and anionic 0.2 parts by weight of polyacrylamide, alkyl ketene dimer emulsion (as ketene dimer content)
4 parts by weight of α4 and 0.4 parts by weight of polyaminopolyamide shrimp chlorohydrin resin were added to form paper having a basis weight of 160 g. The obtained wet paper paper was dried at 110° C. and then mixed with 3 parts by weight of carboxy-modified polyvinyl alcohol, 5 parts by weight of fluorescent whitening agent α00, 2 parts by weight of blue dye α00, 0.2 parts by weight of citric acid and 97 parts by weight of water. 25% of impregnating liquid
g ~ impregnated, dried with hot air at 110℃, and further linear pressure 90
After supercalendering with Kglon, corona discharge treatment is applied to both sides of the base paper for photographic resin-coated paper.
- Manufactured.

Next, apply high-density polyethylene (density 0, 96
A 1:1 mixture of g/aA, M engineering = 5) and low density polyethylene (density 0.92 g/i, M engineering = 5) was coated to a thickness of 30μ using a melt extrusion coating machine at a resin temperature of 330°C. Coated. Next, 30 parts by weight of the master batch of the titanium dioxide pigment described above, 30 parts by weight of high-density polyethylene (density 0.96 g/d, M engineering = 5) and low-density polyethylene (density 0-92 g/ctA, M engineering = 5) A resin composition of 40 parts by weight was heated to a resin temperature of 3.
Polyethylene resin-coated papers containing titanium dioxide pigment were each produced by coating to a thickness of 30μ at 30°C. At that time, the surface of the polyethylene containing titanium dioxide pigment was processed into a completely flat glossy surface, and the surface quality of the back polyethylene was processed into a paper-like matte surface.

The number of microgrits 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. On the resin surface containing the titanium dioxide pigment of the resin-coated paper,
The sample was irradiated for 120 hours using a tomometer (model FAL-25X-HOL), and then the yellow density (hereinafter abbreviated as Y density) on the irradiated surface of the sample was measured and verified using a Macbeth densitometer (model TD-504). The larger the number, the higher the Y concentration, and the higher the Y concentration, the worse the light resistance of the sample.

Table 1 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, the resin pressure is 24 Kg/J or more (sample numbers 7 and 8
), the number of microgrits increases, and on the other hand, when the amount of surface treatment is 0.15% or less (sample numbers 1 and 2), the light resistance becomes significantly worse.

Therefore, the resin pressure of the photographic thermoplastic resin composition in the present invention is less than 20 Kv/cd, 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) For the titanium dioxide pigment used in Example 1,
By adding a sodium silicate aqueous solution to the titanium dioxide slurry before adding the sodium aluminate aqueous solution, At, O, 0.5% by weight of hydrated aluminum oxide and B10. Calculated in the form of 0.25
except that titanium dioxide pigments surface-treated with hydrated silicon oxide were used. A polyethylene resin-coated paper coated with a photographic thermoplastic resin composition was prepared and tested in the same manner as in Example 1. As a result, this resin-coated paper was found to be suitable as a photographic support, as it significantly prevented the generation of microgrit and had excellent light resistance and heat resistance.

(Example 3) In place of the resin composition containing titanium dioxide used in Example 1 to coat the surface of the base paper, 30 parts by weight of a masterbatch of the same titanium dioxide pigment as in Example 1 and ethylene-propylene were added. Polymer (propylene content 0.1% by weight, density 0.
945 g, /diXM = 7) 30 parts by weight and low density polyethylene (density 0.92 g/c!, M = 7) 4
The same procedure as in Example 1 was carried out except that a resin composition containing 0 parts by weight was used.

As a result, the same results as in Example 1 were obtained.

Claims (1)

[Claims] 1) At least a thermoplastic resin and a titanium dioxide pigment
A method for producing a photographic thermoplastic resin composition characterized in that the resin pressure as defined in the specification is less than 20 Kv/di. 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 α2% by weight to L2% by weight (calculated in anhydrous form) based on titanium dioxide. How things are made. 6) The photograph according to claim 3 or 4, wherein the amount of hydrous aluminum oxide treated is 0.2% by weight to L2% by weight (calculated in the form of At, 03) based on titanium dioxide. A method for producing a thermoplastic resin composition for use. 7) The method for producing a photographic thermoplastic resin composition according to claim 1, 2, 3, 4, 5 or 6, wherein the thermoplastic resin is a polyolefin resin. 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 steam mill. Acid manufacturing method.