JPS6126652B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for manufacturing photographic polyolefin resin-coated paper in which a film-like polyolefin resin composition containing titanium dioxide is melt-extruded coated on at least one side of a paper or synthetic paper substrate. A polyolefin resin composition containing titanium dioxide is melt-extruded onto at least one side of a synthetic paper substrate in the form of a film to eliminate poor surface quality due to die lip stains that occur when manufacturing polyolefin resin-coated paper for photography. It is about how to prevent it. More specifically, the present invention relates to a method for producing a photographic support with improved hiding power. The essential structure of photographic polyolefin resin-coated paper is already known; for example, as disclosed in U.S. Pat. This method involves adding titanium dioxide, blue pigment, fluorescent whitening agent, etc. However, when melt-extruding a polyolefin resin composition containing titanium dioxide, especially a polyethylene resin composition, into a film from a slit die, needle-shaped or icicle-shaped deposits or stains (hereinafter simply referred to as die lip) are formed on the tip of the die lip during short extrusion. Die lip stains (referred to as die lip stains) tend to occur, and unfortunately, these die lip stains tend to grow larger and larger as the melt extrusion time progresses. If this die lip stain occurs during melt extrusion coating, vertical streaks may appear on the surface of photographic polyolefin resin coated paper manufactured as is, or streak-like unevenness may occur due to uneven coating amount. In some cases, dirt adheres to the film and is coated, causing foreign matter to appear. As a result, the surface quality of the produced polyolefin resin-coated paper is significantly impaired, making it unsuitable as a photographic support that requires excellent surface quality, and having no commercial value. Additionally, the only way to completely remove die lip stains that have occurred is to stop production and clean the die lip, which requires a great deal of effort and time and results in a significant drop in productivity. Therefore, an urgent solution was needed. As a result of various studies conducted by the present inventors on preventing the occurrence of die lip stains, it has been found that titanium dioxide contained in polyolefin resin compositions has a major problem. In terms of the content of titanium dioxide, if the content of titanium dioxide in the polyolefin resin is low, die lip stains will occur less, but the hiding power will be small and it cannot be used as a photographic support. It was found that when the amount is high, the hiding power is sufficient, but the generation of dye lip stains is significant. It has also been found that there is a very serious problem not only in the amount added but also in the titanium dioxide itself used. Of course, if TiO ₂ is not contained in the resin layer of the photographic support, the sharpness will be significantly deteriorated, rendering it useless as a photographic support. That is, titanium dioxide used in the photographic industry is usually prepared by precipitating hydrous aluminum oxide or hydrous aluminum oxide and hydrous silicon dioxide on the surface of titanium dioxide particles, as described in JP-A No. 52-35625. Modified titanium dioxide, etc.
The reason why highly surface-treated titanium dioxide is used in the photographic industry is as follows:
As described in No. 35625, titanium dioxide that has not been surface-treated or has been surface-treated only very lightly (the amount of surface treatment agent treated with respect to titanium dioxide is less than 0.2% by weight). If used, (1) it will have an adverse effect on the photographic emulsion; (2) The dispersibility of titanium dioxide deteriorates. (3) Adhesion between the resin layer and the emulsion layer deteriorates. (4) The white background of the photo tends to discolor over time. (5) The whitening effect of fluorescent brighteners is poor. The resin layer of photographic polyolefin-coated paper, which has drawbacks such as It can be said that it is never used. However, the more sophisticated surface treatments are applied to meet the demands of the photographic industry, the more severe die lip stains occur. The present inventors have identified the contradictions between the two, namely, quality problems such as the white background of photographs easily discoloring over time (hereinafter referred to as photodeterioration), and operational problems due to the severe occurrence of die lip stains. (Resulting in quality defects) As a result of intensive research to solve the above problems at the same time, we have arrived at the present invention. The present invention provides a method for manufacturing photographic polyolefin resin-coated paper in which a polyolefin resin composition containing titanium dioxide is melt-extruded and coated on at least one side of a paper or synthetic paper substrate in the form of a film. , polyolefin resin, and organopolysiloxane against titanium dioxide.
The present invention relates to a method for producing a photographic support characterized by comprising 0.04 to 4% by weight of surface-treated titanium dioxide. When a polyolefin resin composition containing titanium dioxide surface-treated with organopolysiloxane in an amount of 0.04 to 4% by weight based on titanium dioxide is applied using a melt extruder, the occurrence of die lip stains is significantly suppressed. , it is possible to produce photographic polyolefin resin-coated paper with almost no machine downtime. In addition, when the photographic polyolefin resin-coated paper made in this way is used as a photographic support, a photographic support using titanium dioxide surface-treated with commonly used aluminum oxide, silicon dioxide, etc. In comparison, high quality products with no inferiority in terms of photodeterioration can be obtained. Furthermore, it is possible to obtain a photographic support with higher hiding power than when using titanium dioxide without surface treatment or titanium dioxide treated with alumina. Furthermore, prior to the organopolysiloxane surface treatment, the titanium dioxide is further treated with organopolysiloxane in an amount of 0.2 to 1.2% by weight (calculated in the form of Al ₂ O ₃ ) based on the titanium dioxide with hydrous aluminum oxide. A polyolefin resin composition containing titanium dioxide surface-treated with 0.04 to 4% by weight of titanium dioxide with siloxane can greatly improve the hiding power of a photographic support. From the results of previous research by the inventors,
It has been found that die lip stains are more likely to occur when high density polyethylene is contained in the polyolefin resin composition or when the titanium dioxide content is increased in the polyolefin resin composition. However, since photographic supports usually have a photographic emulsion layer on the surface of the titanium dioxide-containing resin layer, curling tends to occur because the structures of the front and back surfaces of the photographic support are significantly different. In order to correct this, it is a common practice in the photographic industry to incorporate high-density polyethylene resin into the titanium dioxide-containing resin layer and the back resin layer to balance the curl. Therefore, although it is known that the inclusion of high-density polyethylene resin in a polyolefin resin composition promotes the occurrence of die lip stains, the reality is that its use is unavoidable from the standpoint of quality. In addition, increasing the content of titanium dioxide in the resin layer of a photographic support improves sharpness, so it is desirable to increase the content of titanium dioxide in photographic supports that require high quality. As the content increases, the occurrence of die lip stains increases significantly, making it no longer possible to manufacture the product. Therefore, at present, photographic supports must be manufactured with the titanium dioxide content kept to a minimum, and there is a strong demand for photographic supports with a high titanium dioxide content in order to obtain high quality. As a result of research to meet the demands of this industry,
The polyolefin resin composition according to the present invention can increase the titanium dioxide content in the resin layer of a photographic support. As a result, a photographic support with extremely good sharpness can be obtained. As the organopolysiloxane used in the present invention, dimethylsiloxane, dimethylphenylsiloxane, methylhydrodienesiloxane, etc. can all be used, but methylhydrodienesiloxane is particularly preferred in the present invention. or,
The surface treatment amount of these organopolysiloxanes relative to titanium dioxide is preferably 0.04 to 4% by weight. If the surface treatment amount is less than 0.04% by weight, no effect will be obtained, and if it exceeds 4% by weight, screw slip may occur in the melt extruder.
Sufficient extrusion rate cannot be maintained. In the present invention, the degree of polymerization of the organopolysiloxane can be from 3 to 2,200, particularly preferably from 5 to 1,000, in the case of dimethylsiloxane. After surface-treating titanium dioxide with these organopolysiloxanes, heat treatment at 50 to 250°C for several minutes to several tens of hours provides a better surface treatment, and is most effective especially in the case of methylhydrodiene. The titanium dioxide used in the present invention is rutile type,
Any anatase type can be used. Further, titanium dioxide without surface treatment can also be used, and more preferably titanium dioxide is surface-treated with hydrous aluminum oxide in an amount of 0.2 to 1.2% by weight (calculated in the form of Al ₂ O ₃ ) based on titanium dioxide. Furthermore, the particle size of titanium dioxide used in the present invention is not particularly regulated;
Usually commercially available particle diameters of about 0.1 to 1 μm may be used, but preferably particle diameters of about 0.15 to 0.35 μm are used. The surface treatment method with hydrous aluminum oxide for obtaining titanium dioxide used in the present invention may be carried out, for example, by the method described in Japanese Patent Publication No. 17620/1983. Surface treatment with organopolysiloxane is usually carried out in the powder industry, for example, by treating the surface of titanium dioxide with a solution of organopolysiloxane dissolved in a suitable organic solvent, and then recovering the organic solvent. This is done by a processing method, etc. If the content of titanium dioxide in the polyolefin resin is less than 5% by weight based on the polyolefin resin composition, the hiding power as a photographic support will be insufficient, while if it is more than 40% by weight, fluidity etc. will decrease. 9% by weight to 9% by weight is particularly preferable.
It is in the range of 25% by weight. As the polyolefin in the present invention, reduced density polyethylene, high density polyethylene, and polypropylene having various densities and melt viscosity indexes can be used alone or in combination. In the present invention, due to the excellent effects of titanium dioxide as referred to in the present invention, there is no need to particularly incorporate photodegradation inhibitors or die lip stain prevention aids into the polyolefin composition, but if necessary, If available, metal salts of fatty acids, etc. may be blended. Examples of metal salts of fatty acids that can be used in the present invention include zinc stearate, calcium stearate, aluminum stearate, magnesium stearate, zirconium octylate, sodium palmitate, calcium palmitate, and sodium laurate. The amount added is 0.01 to 5
It can be used in a range of 0.02 to 2% by weight. In addition to titanium dioxide, the polyolefin resin composition of the present invention further contains zinc oxide, talc,
White pigments such as calcium carbonate, fatty acid amides such as stearic acid amide and arachidic acid amide,
Tetrakis [methylene-3 (3,5-di-tert-
Butyl-4-hydroxy-phenyl)propionate]methane, 2,6-di-tert-butyl-4
-Antioxidants such as methylphenol, color pigments such as ultramarine blue and red red pigment, and optical brighteners may be added. The polyolefin resin coated paper in the present invention is
It is usually manufactured by melt-extruding a polyolefin resin composition onto a paper or synthetic paper substrate (hereinafter simply referred to as base paper) that runs through a slit die in the form of a film. At that time, the melt extrusion temperature is preferably 200°C to 350°C. As a slit die, T
A type die, an L-type die, and a fishtail type die are preferred, and the slit opening diameter is preferably 0.1 to 1 mm. 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 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 polyolefin resin-coated paper in which both sides of the base paper are coated with resin, the resin surface containing titanium dioxide (emulsion coated surface) can be glossy, matte, or silky depending on the application. The back surface is usually a matte surface, and activation treatments such as corona discharge treatment and flame treatment can be performed on the front surface or both the front and back surfaces as necessary. The base paper used in the practice of the present invention may be ordinary natural pulp, paper, synthetic fiber paper, or so-called synthetic paper made of agglomerated synthetic resin film. Natural pulp paper based on wood 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 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 such as cationized starch, cationized polyacrylamide, anionized polyacrylamide, carboxy-modified polyvinyl alcohol, gelatin, etc., and sizing agents such as fatty acid salts, rosin derivatives, dialkyl ketene dimer emulsions, petroleum resin emulsions, Pigments such as ammonium salt of styrene-maleic anhydride copolymer alkyl ester, clay, kaolin, calcium carbonate,
Wet paper strength agents such as barium sulfate and titanium dioxide; melamine resins, urea resins, and epoxidized polyamide resins; fixing agents such as polyvalent metal salts such as aluminum sulfate and aluminum chloride; and cationic polymers such as cationized starch. , PH regulators such as caustic soda, soda carbonate, and hydrochloric acid; inorganic electrolytes such as common salt and mirabilite; in addition, dyes, optical brighteners, latex, and the like may be contained in appropriate combinations. The photographic support according to the present invention can be provided with various silver halide photographic emulsion layers. for example,
A silver chloride, silver bromide, silver chlorobromide, silver iodobromide, or silver chloroiodobromide emulsion layer 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 polyvinylpyrrolidone, polyvinyl alcohol, and polysaccharide nitrate 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; antifoggants and stabilizers include hydroxytriazolopyrimidine compounds and mercapto heterocyclic compounds; As membrane agents, formalin, vinyl sulfone compounds,
Aziridine compounds, etc., as coating aids, benzene sulfonate, sulfosuccinic acid ester salts, etc., anti-staining agents, dialkylhydroquinone compounds, etc., ultraviolet absorbers, benzotriazole compounds, etc., as well as optical brighteners, sharpness improvers. A dye, an antistatic agent, a PH regulator, and further water-soluble iridium, rhodium compounds, etc. can be contained in an appropriate combination during the production and dispersion of silver halide. Next, in order to explain the present invention more specifically,
An example will be described. Example 1 Low density polyethylene (MI=4, density 0.923) 70
30 parts by weight of titanium dioxide and 1.5 parts by weight of zinc stearate were thoroughly kneaded at 150°C using a Banbury mixer in the combinations shown in Table 1 (note 1) to obtain a masterbatch containing titanium dioxide.
34 parts by weight of the titanium dioxide-containing masterbatch thus obtained was dry mixed with 36 parts by weight of low-density polyethylene (MI=5, density 0.918) and 30 parts by weight of high-density polyethylene (MI=5, density 0.968) as diluent resins. Then, a coating speed of 100 m/min was applied to a polyester film with a basis weight of 105 g/m ² using a melt extruder.
The combinations listed in Table 1 were applied by melt extrusion at a melting temperature of 320° C. to a coating weight of 30 g/m ² . This melt extruder is a screw type extruder with an extrusion opening diameter of 65 mm and a T-shaped extruder with a width of 750 mm.
It has a die. The cast cooling roll had a smooth flat surface and was treated with hard chrome plating. Note 2 in Table 1 indicates the number of die lip stains in each sample 2 hours after the start of melt extrusion. Note 3 also shows the results of measuring the opacity of each sample obtained using the combinations in Table 1 using Hunter whiteness (using a G filter). The larger the number, the higher the hiding power. The experimental results obtained are shown in Table 1. From the results in Table 1, water content, aluminum oxide 2%
It can be seen that the surface-treated titanium dioxide is not suitable for practical use due to the occurrence of die lip stains. on the other hand,
Titanium dioxide without surface treatment, dimethylsiloxane, and dimethylphenylsiloxane all showed good results, with no die lip staining occurring. In addition, the opacity of titanium dioxide without surface treatment and titanium dioxide treated with water and 2% aluminum oxide both show low opacity, but titanium dioxide treated with organopolysiloxane has a surface treatment amount of 0.03% by weight. It can be seen that both exhibit high opacity. In addition, each sample was subjected to sunlight aeration for one month to examine its light resistance. As a result, No. 2
~ No. 10 showed almost no discoloration, but
It was found that in the case of No. 1 titanium dioxide without surface treatment, discoloration and fading were significant. Example 2 Using exactly the same resin as in Example 1, melt extrusion coating was performed in the combinations listed in Table 2. The experimental method was the same as in Example 1. The results obtained are shown in Table 2. From the experimental results in Table 2, it can be seen that, similar to the results in Table 1, all titanium dioxides treated with 0.05% by weight or more of methylhydrogensiloxane have high opacity. Furthermore, in the case of the titanium dioxide obtained in Table 2 that was treated in combination with the hydrous aluminum oxide treatment and the methylhydrogensiloxane treatment, the titanium dioxide obtained in Table 1 was treated with higher impurities than the titanium dioxide treated with organopolysiloxane alone obtained in Table 1. It can be seen that it shows transparency. In addition, as in the examples, the sunlight resistance was examined and it was found that in the case of No. 11 TiO ₂ without surface treatment, discoloration and fading were significant. Example 3 Low density polyethylene (MI=9, density 0.918) 70
30 parts by weight of titanium dioxide and 1.5 parts by weight of zinc stearate were thoroughly kneaded at 150°C using a Banbury mixer in the combinations shown in Table 3 (note 1) to obtain a masterbatch containing titanium dioxide.
50 parts of the titanium dioxide-containing masterbatch thus obtained was dry mixed with 20 parts by weight of low density polyethylene (MI = 9, density 0.918) and 30 parts by weight of high density polyethylene (MI = 7, density 0.962) as diluent resins. . Thereafter, a photographic support was obtained in the same manner as in Example 1. The results obtained are shown in Table 3. From the experimental results in Table 3, the content of titanium dioxide in the polyethylene resin composition is as high as 15 parts by weight in the case of titanium dioxide without surface treatment and titanium dioxide treated with water, aluminum oxide treatment, and methylhydrodiene siloxane. Despite this, no die lip stains occurred even after 2 hours of melt extrusion, but in the case of hydrous titanium dioxide treated with 2% aluminum oxide, a total of 100 die lip stains were produced on the front and rear sides after just 15 minutes. The above die lip stains occurred. Opacity is No.31 and No.33 to No.36.
It can be seen that this is a significant improvement compared to No. 32. The basis weight of polyethylene resin compositions No. 31 to No. 36 listed in Table 3 was prepared using the melt extruder described in Example 1.
Melt extrusion coating was carried out on 160 g/m ² photographic base paper at a coating speed of 100 m/min, at a melting temperature of 320° C., and in a coating weight of 30 g/m ² . A black and white silver halide photographic emulsion layer was provided on the thus obtained photographic supports No. 31 to No. 36, and the resolving power was tested using a resolving power meter.
In addition, as in Example 1, as a result of examining the sunlight resistance, it was found that No. 33 to No. 36 had significantly superior resolution compared to No. 31 and No. 32. In the case of TiO ₂ , it was found that discoloration and fading were significant.

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Claims (1)

[Scope of Claims] 1. When manufacturing polyolefin resin-coated paper for photography by melt extrusion coating a polyolefin resin composition containing titanium dioxide in the form of a film on at least one side of a paper or synthetic paper substrate, The resin composition is a polyolefin resin and an organopolysiloxane with a ratio of 0.04 to 4 relative to titanium dioxide.
1. A method for producing a photographic support comprising surface-treated titanium dioxide in weight percent. 2. A patent claim in which the titanium dioxide is titanium dioxide surface-treated with 0.2 to 1.2% by weight of titanium dioxide (calculated in the form of _Al2C3 ) with hydrous aluminum oxide prior to _{organopolysiloxane} surface treatment. A method for producing a photographic support according to item 1. 3. The method for producing a photographic support according to claim 1 or 2, wherein the polyolefin resin is a polyethylene resin. 4. The method for producing a photographic support according to claim 1, 2 or 3, wherein the polyolefin resin contains at least one type of high-density polyolefin resin. 5. The method for producing a photographic support according to claim 1, 2, 3 or 4, wherein the content of titanium dioxide in the polyolefin composition is 10% by weight or more.