JPH0476462B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a photographic support 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. relates to a photographic support characterized in that the titanium dioxide is surface-treated with an organoaluminum compound. (Prior Art) The essential structure of photographic resin-coated paper is already known. For example, as disclosed in U.S. Pat. No. 3,501,298, both sides of a paper base are coated with resin, and the emulsion-coated side is In this method, the resin layer contains a titanium dioxide pigment, a blue pigment, a fluorescent brightener, etc. 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, especially when preparing a masterbatch or compound by ordinary melt kneading using a Banbury mixer, kneader, etc., relatively coarse pigment particles tend to be dispersed as they are without being dispersed into a fine state in the thermoplastic resin. Therefore, there are undispersed pigment particles in the masterbatch or compound.
As a result, on the resin side of the 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, Microgrit, which is minute foreign matter or minute particles, 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 using 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. Furthermore, resin-coated paper containing microgrit does not allow sufficient dispersion of titanium oxide particles, and the hiding power of the photographic support is greatly reduced. (Object of the Invention) An object of the present invention is to provide a photographic support that does not generate microgrit and has greatly improved hiding power. Examples of the organoaluminum compound which is the titanium dioxide surface treatment agent for improving the dispersibility of polyphrein resin in the present invention include aluminum ethylate, aluminum isopropylate, monosec-butoxyaluminum diisopropylate, ethyl acetoacetate aluminum diisopropylate, and aluminum trisethyl. Acetoacetate, aluminum monoacetylacetonate bisethyl acetoacetate, aluminum trisacetylacetonate, diisopropoxyaluminum monooleylacetoacetate, monoisopropoxyaluminum bisoleylacetoacetate, monoisopropoxymonomethacrylaluminum monooleylacetoacetate, mono Isopropoxyaluminum monooleate monoethylacetoacetate, monoisopropoxyaluminum monoethylacetoacetate monooleyl acetate, diisopropoxyaluminum monolauryl acetoacetate, diisopropoxyaluminum monostearylacetoacetate, diisopropoxyaluminum monoisostearylacetoacetate , monoisopropoxyaluminum monomethacrylate monooleylacetoacetate, monoisopropoxyaluminum monooleate monoethylacetoacetate, monoisopropoxyaluminum monorodinate monolauryl acetoacetate, diisopropoxyaluminum monoabiethylacetoacetate, monoisopropoxyaluminum Mono-N-lauroyl-β
-Alanate monolauryl acetoacetate and its alkyl substituted products. Among these, aluminum monoacetylacetonate bisethylacetoacetate and aluminum trisacetylacetonate are particularly preferred. The above-mentioned organoaluminum compounds in the present invention may be used alone or in a suitable combination of two or more. The amount of titanium dioxide surface treated with these organoaluminum compounds is preferably 0.02 to 5.0% by weight, particularly 0.2 to 1.5% by weight, based on titanium dioxide. If the amount is less than 0.02%, titanium dioxide cannot be sufficiently dispersed, and when the resin is melt-coated onto a paper substrate, the die lip end of the extruder becomes dirty, making it difficult to obtain a sufficiently smooth photographic support surface. Also,
If the treatment amount is more than 5.0%, the proportion of organoaluminum compounds that do not interact with the titanium dioxide surface will increase, causing thermal decomposition during melt extrusion of polyolefin, producing a large amount of smoke during extrusion coating, and reducing workability. Not only is this bad, but smoke gets in between the cooling roll and the resin layer, making it difficult to obtain a smooth surface of the photographic support. Various methods can be used to coat the surface of titanium dioxide particles with an organoaluminum compound. That is,
A method in which titanium dioxide is immersed in a non-aqueous solvent in which an organoaluminum compound is dissolved, stirred, and then the solvent is dried; a method in which a solution of an organoaluminum compound in a solvent is sprayed onto titanium dioxide and then dried; There are methods such as direct atomization of the compound, spraying the titanium dioxide while stirring, and then drying, and other methods as long as the result is a uniform treatment on the titanium dioxide surface, but in particular, a method of spraying with a solvent. is preferred. The solvent for dissolving the organoaluminum compound should be one that does not decompose and forms a uniform solution when the specified organoaluminum compound is dissolved, and that can be easily removed without adversely affecting the powder surface after treatment. It doesn't matter what type it is, but n-
Hexane, toluene, xylene, acetone, isopropyl alcohol, methanol and the like are preferred. Titanium dioxide in the present invention is anatase type,
Any rutile type can be used, and titanium dioxide whose surface is partially coated with a hydrous metal oxide such as hydrous aluminum oxide, hydrous iron oxide, etc. may also be used. In particular, further effects can be obtained by surface-treating titanium dioxide which has been previously surface-treated with hydrated aluminum oxide (0.2 to 1.2% by weight (in terms of Al ₂ O ₃ ) based on titanium dioxide) with an organic aluminum compound. The titanium oxide pigment whose particle surface has been coated with an organoaluminum compound is melt-kneaded with a resin and an appropriate amount of lubricant if necessary in a kneading extruder, heated kneading roll, Banbury mixer, kneader, etc. to create a masterbatch. Use by diluting with polyolefin resin during melt extrusion. The concentration of titanium oxide pigment in the masterbatch is preferably 20 to 70% by weight. In the present invention, melt extrusion coating refers to a method in which a polyolefin melt-extruded into a film from an extruder through a die is coated onto a traveling paper substrate. The melting temperature of the polyolefin in the die is about 250 to 350°C, preferably 280 to 320°C, and the running speed of the paper substrate is about 50 to 400 m/min, preferably 80 to 250 m/min. The polyolefin used in the present invention can be of any type as long as it has the ability to form a film when extruded from a hot melt extrusion device, but even if it does not have the ability to form a film alone, its properties can be expressed by mixing it with other polyolefins. Even something like that is acceptable. Further, the molecule may have an alkyl group, a hydroxyl group, a carboxyl group, etc. as a side chain, or a carbonyl group, a double bond, etc. may be copolymerized. The easiest to use resins are low density polyethylene, high density polyethylene, polypropylene, and resins mixed therewith. Furthermore, known fluorescent brighteners, antioxidants, antistatic agents, coloring pigments, etc. may be added to these resins as desired. The paper used in the present invention can be made of natural pulp, synthetic pulp, or a mixture thereof. Its thickness is approximately 40 to 400 μm, more preferably 50 to 260 μm. Furthermore, when making the paper used in the present invention, various polymer compounds and additives can be included. For example, dry paper strength enhancers such as cationized starch, cationized polyacrylamide, anionized polyacrylamide, carboxyl-modified polyvinyl alcohol, gelatin, etc., and sizing agents such as 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 dioxide, etc., wet paper strength agents As, melamine resin, urea resin,
Epoxidized polyamide resin, etc. As a fixing agent, polyvalent metal salts such as aluminum sulfate and aluminum chloride, cationic polymers such as cationized starch, etc. As a PH regulator, caustic soda, soda carbonate, hydrochloric acid, etc. As an inorganic electrolyte, salt, In addition to Glauber's salt, dyes, fluorescent whitening agents, 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 halogenated 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,
Sulfur compounds, etc., as antifoggants or stabilizers; hydroxytriazolopyrimidine compounds, mercapto-heterocyclic compounds, etc.; hardeners; formalin, vinyl sulfone compounds, aziridine compounds, etc., as coating aids; benzenesulfonic acid; salt, sulfosuccinate salt, etc.
Anti-staining agents such as dialkylhydroquinone compounds, ultraviolet absorbers such as benzotriazole compounds, fluorescent whitening agents, sharpness-enhancing dyes, antistatic agents, PH regulators, and water-soluble agents during the production and dispersion of silver halides. It is possible to contain a suitable combination of chemical iridium, rhodium compounds and the like. (Examples of the Invention) Next, in order to explain the present invention more specifically,
An example will be described. Example Low density polyethylene (MI=5.0, density 0.918) 50
Parts by weight and 50 parts by weight of titanium dioxide surface-treated with the organoaluminum compound listed in Table 1 were kneaded at 150°C using a Banbury mixer to obtain a titanium dioxide masterbatch. 26 parts by weight of this masterbatch and low density polyethylene (MI
= 4.0, density 0.920) and 24 parts by weight of high-density polyethylene (MI = 5.0, density 0.965) were dry mixed and coated on a polyester film with a basis weight of 150 g/m ² using a melt extruder at a coating speed of 100 m/m. min, melting temperature
Melt extrusion coating was carried out at 320°C with a coating weight of 30 g/m ² . This melt extruder has a screw type extruder with an extrusion diameter of 65 mm and a T-die with a width of 750 mm. The cast cooling roll had a smooth flat surface and was treated with hard chrome plating. Comparative example Low density polyethylene (MI=5.0, density 0.918) 50
Part by weight, 50 parts by weight of untreated titanium dioxide and zinc stearate at 150°C using a Banbury mixer.
A titanium dioxide masterbatch was obtained.
This masterbatch was diluted in the same manner and in the same proportions as in the Examples and melt extrusion coated. The opacity in Table 1 shows the results measured using a Hunter whiteness meter (using a G filter). The higher the number, the higher the concealment power. Also shown are the results of visually counting the number of microgrids generated on the polyethylene resin surface for each sample. From the results in Table 1, it can be seen that no matter which organoaluminium compound treated titanium dioxide is used, both the opacity and the microgrid are better than the untreated product and the zinc stearate kneaded product.

[Table] Zinc thearate was added during kneading with a Banbury mixer.

Claims (1)

[Scope of Claims] 1. In a photographic support in which a polyolefin resin composition containing titanium dioxide is melt-extruded coated in the form of a film on at least one surface of a paper or synthetic paper substrate, the polyolefin resin composition is a polyolefin resin composition containing titanium dioxide. A photographic support comprising titanium dioxide surface-treated with a resin and an organoaluminium compound. 2. The photographic support according to claim 1, wherein the weight ratio of the organoaluminum compound to titanium dioxide is 0.02 to 5.0% by weight. 3. Claim 1 or 3, wherein the titanium dioxide is titanium dioxide that has been surface-treated with hydrous aluminum oxide in an amount of 0.2 to 1.2% by weight (in terms of Al ₂ O ₃ ) based on titanium dioxide, prior to the organic aluminum surface treatment. Photographic support according to item 2. 4. The photographic support according to claim 1, 2, or 3, wherein the polyolefin resin is a polyethylene resin.