JPH0476464B2 - - Google Patents

Description

[Detailed description of the invention]

(A) Field of Industrial Application The present invention relates to a support for photographic paper, and more particularly, on at least one side of a paper or synthetic paper substrate,
This invention relates to resin-coated paper coated with a resin composition containing titanium dioxide by elution and extrusion into a film. (B) Prior Art The essential structure of resin-coated paper for photography is already known. For example, as disclosed in U.S. Pat. No. 3,501,198, both sides of the 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, and a fluorescent whitening agent. In the first place, the method of incorporating pigments into polyolefin resin is to create a so-called master batch in which pigments are contained in resin at a high concentration in advance, and then dilute and mix them with a diluent resin to the desired ratio, or to use pigments in resin. It is usual to prepare and use a so-called compound containing a desired composition ratio from the beginning. However, especially when preparing a masterbatch or compound by ordinary melt-kneading using a Banbury mixer, kneader, etc., there is a tendency for relatively coarse pigment particles to be dispersed in the resin without being dispersed in a fine state. Thus, undispersed pigment particles are present 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, which is minute foreign matter or minute particles, is 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's commercial value is completely lost. 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. (C) Object of the invention The object of the invention is to provide a photographic support that does not generate microgrit and has greatly improved hiding power. (D) Structure of the Invention The object of the present invention is to provide a photographic resin-coated paper in which at least one surface of a paper or synthetic paper substrate is coated with a resin composition consisting of at least titanium dioxide and a resin. This has been achieved by a photographic resin-coated paper characterized in that it is coated with at least one kind of amide compound represented by the following general formula () or () during the manufacturing process. R ₁ −CONH−R ₂ () In the above formula, R ₁ and R ₂ represent a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, and R ₃ represents a substituted or unsubstituted alkylene group having 2 to 20 carbon atoms. R ₁ and R ₂ in the general formula () may be the same or different, and R ₁ , R ₂ and R ₃ may be linear or branched. The amount of the amide compound used to treat the surface of titanium dioxide in the present invention is preferably 0.01 to 2% by weight, particularly preferably 0.1 to 1.0% by weight, based on titanium dioxide.
If the amount is less than 0.01%, titanium dioxide cannot be sufficiently dispersed and microgrit is generated, and if the amount is more than 2%, slippage occurs during masterbatch production, resulting in insufficient kneading and an increase in microgrit. The method for coating the surface of titanium dioxide particles with the amide compound used in the present invention is to immerse and stir titanium dioxide in a solution of the amide compound in a suitable solvent, and then dry the solvent. A method of injecting an amide compound solution when pulverizing titanium dioxide with a fluid energy pulverizer such as a micronizer or a jet mill. There are methods of mixing the amide compound with the amide compound using a high shear mixer such as a Henschel mixer or a super mixer, and a method of spraying and mixing a solution of the amide compound in a low-boiling non-aqueous solvent is particularly preferred. Titanium dioxide in the present invention is anatase type,
Both rutile types can be used, and the surface of titanium dioxide can be replaced with hydrous metal oxides, such as hydrous aluminum oxide.
It may also be titanium dioxide whose surface is partially coated with hydrated iron oxide or the like. In particular, further effects can be obtained by further surface-treating titanium dioxide, which has been previously surface-treated with hydrous aluminum oxide (0.2 to 1.2% by weight of titanium dioxide (in terms of Al ₂ O ₃ )) with the amide compound of the present invention. . The titanium oxide pigment whose particle surface has been coated with the amide compound of the present invention 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 make a masterbatch. It is diluted with polyolefin resin and used in a melt extruder. 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. Also, the molecule contains alkyl groups, hydroxyl groups, carboxyl groups,
etc. may be present in the side chain, or carbonyl groups, double bonds, etc. may be copolymerized. The easiest to use resins are low density polyethylene, high density polyethylene, polypropylene, and resins mixed therewith. In addition, these resins may contain known fluorescent brighteners, antioxidants, antistatic agents,
Coloring pigments etc. may be added. 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, cationized starch as a dry paper strength enhancer,
Cationized polyacrylamide, anionized polyacrylamide, carboxyl-modified polyvinyl alcohol, gelatin, etc., as a sizing agent, fatty acid salt, rosin derivative, dialkyl ketene dimer emulsion, petroleum resin emulsion, ammonium of styrene-maleic anhydride copolymer alkyl ester Salts, etc., as pigments, clay, kaolin, calcium carbonate, barium sulfate, titanium dioxide, etc., wet paper strength agents, melamine resin, urea resin, epoxidized polyacrylamide, etc., as fixing agents,
Polyvalent metal salts such as aluminum sulfate and aluminum chloride, cationic polymers such as cationized starch, etc. As pH regulators, caustic soda, soda carbonate, hydrochloric acid, etc. As inorganic electrolytes, common salt, mirabilite, etc.
Other dyes, optical brighteners, latex, etc. can be contained in appropriate combinations. The photographic resin-coated paper according to the present invention 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 containing 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, as sensitizing dyes, cyanine dyes, merocyanine dyes, etc., as chemical sensitizers, water-soluble gold compounds, sulfur compounds, etc., as antifoggants or stabilizers, hydroxytriazolopyrimidine compounds,
Mercapto-heterocyclic compounds, etc., as hardeners, formalin, vinyl sulfone compounds, aziridine compounds, etc., as coating aids, benzenesulfonate, sulfosuccinic acid ester salts, etc., as anti-staining agents, dialkylhydroquinone compounds, etc.
Contains benzotriazole compounds as ultraviolet absorbers, other optical brighteners, sharpness-improving dyes, antistatic agents, PH regulators, and water-soluble iridium and rhodium compounds when producing and dispersing silver halide in appropriate combinations. I can force it. (E) 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 amide 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) 50 parts by weight and high density polyethylene (MI=
5.0, density 0.965) 24 parts by weight were dry mixed, and the basis weight
Melt extrusion coating was applied to a 105 g/m ² polyester film using a melt extruder at a coating speed of 100 m/min, a melting temperature of 320° C., and a coating amount of 30 g/m ² . This melt extruder is a screw type extruder with an extrusion port diameter of 65 mm and a 750 mm extruder.
It has a T-die of width. 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 larger the number, the higher the hiding power. Also shown are the results of visually counting the number of microgrits generated on the polyethylene resin surface for each sample.

[Table] From the results in Table 1, it can be seen that using titanium dioxide treated with any of the amide compounds used in the present invention has better opacity and microgrit than untreated and zinc stearate kneaded products. I understand.

Claims (1)

[Claims] 1. At least one surface of the paper or synthetic paper substrate is
In photographic resin-coated paper coated with a resin composition consisting of at least a titanium dioxide pigment and a resin, the titanium dioxide is formed during the manufacturing process of at least an amide compound represented by the following general formula () or (). A photographic resin-coated paper characterized by being coated with one type of paper. R ₁ −CONH−R ₂ () In the above formula, R ₁ and R ₂ are substituted or unsubstituted alkyl groups having 1 to 20 carbon atoms, and R ₃ is a substituted or unsubstituted alkyl group having 2 to 20 carbon atoms.
represents a substituted or unsubstituted alkylene group. 2. The photographic resin-coated paper according to claim 1, wherein the treatment amount of general formula () and/or () is 0.01 to 2% by weight based on titanium dioxide. 3 Titanium dioxide has the general formula () and or ()
The photographic resin according to claim 1 or 2, which is titanium dioxide that has been surface-treated with hydrous aluminum oxide in an amount of 0.2 to 1.2% by weight based on titanium dioxide (in terms of Al ₂ O ₃ ) prior to treatment. coated paper. 4. The photographic resin-coated paper according to claim 3, wherein the resin is a polyolefin resin. 5. The photographic resin-coated paper according to claim 4, wherein the polyolefin resin is polyethylene.