Printing paper

Abstract

1. A photographic paper comprising a base layer having an average surface roughness (Sa) of at least 0.7 μm and an outermost layer comprising a hydrophilic colloid binder and colloidal silica, (i) the weight ratio of colloidal silica to hydrophilic colloid binder in the outermost layer is 0.05:1 to 0.28:1; and (ii) The amount of colloidal silica present in the outermost layer is 8 mg / m 2 ~280mg / m 2 In the range of The photographic paper. The photographic paper is useful for producing "noise-free" photobooks.

Description

Technical Field

[0001] The present invention relates to photographic paper, its production and use for making album books.

Background Art

[0002] Typically, photographic paper includes a base layer coated with one or more photosensitive chemical layers. In the case of color photography, the paper typically includes three photosensitive emulsion layers (yellow, magenta, and cyan), optionally together with other layers, to provide a full-color image.

[0003] During manufacture and storage, photographic paper may have the problem of sticking together due to the inherent tackiness of its outermost layer. In use, photographic paper is exposed in a controlled manner to create an image thereon, for example, using an image obtained on camera film or using a digital image. Next, the desired image is developed, and the photographic paper carrying the obtained desired image is often called a photograph. The photographs may be stacked "back to back" with other photographs and handed to the photographer or mailed. Thereafter, it is very common for the photographs (i.e., the photographic paper carrying the desired images) to be incorporated into an album book, where the photographs come into contact with each other in a "facing" manner as a result of being on opposite pages. This "facing" contact can cause problems, especially when the album book is stored under high temperature and / or humid conditions. The photographs tend to stick and can damage the pages of the album book, and in some cases, ruin irreplaceable family photographs.

[0004] One way to prevent photos from sticking to each other in an album book is to place a lightweight paper interfoil between the photos as a barrier. However, this makes the album more expensive, and the interfoil is prone to damage and hinders the easy viewing of two open pages at once. There is also a possibility that the photos will stick to the interfoil.

[0005] European Patent No. 2619628 addresses the problem of prints, especially prints carrying images stored in an album book or other environment, sticking together. Photo books with a rough base layer (i.e., an average surface roughness (Sa) of at least 0.7 μm) have a problem with noise (e.g., creaking sounds) generated when turning, bending, and / or moving the pages. The problem of noise usually does not occur when the base layer is smooth (e.g., as used to produce a glossy photo book), but when producing a photo book with a rough base layer and having a silk finish, raster finish, or matte finish, the noise during page turning can be distracting and unpleasant for the customer. The present invention addresses the problem of reducing or completely eliminating the volume of such noise in non-glossy photo books.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Summary of the Invention

[0007] A photographic print paper according to the present invention includes a base layer having an average surface roughness (Sa) of at least 0.7 μm and an outermost layer containing a hydrophilic colloidal binder and colloidal silica, (i) the weight ratio of colloidal silica to hydrophilic colloidal binder in the outermost layer is 0.05 to 0.28; and (ii) The amount of colloidal silica present in the outermost layer is 8 mg / m 2 ~280 mg / m 2 in the range of, providing the photographic paper.

Embodiments for Carrying Out the Invention

[0008] The components of the photographic paper depend to some extent on whether an image has been developed, i.e., whether the photographic paper has been used. Before an image is developed on the photographic paper, the photographic paper typically includes a base layer (e.g., a polyester or resin-coated paper), one or more photosensitive emulsion layers (e.g., layers that generate yellow, magenta, or cyan colors), and the outermost layer on top of the one or more photosensitive emulsion layers. After the image is developed, the photographic paper typically contains the same components, but is different in that it has been exposed in a controlled manner to develop a desired image and the photosensitive layer is no longer photosensitive.

[0009] The average particle size of the colloidal silica is preferably in the range of 2 to 70 nm, more preferably 2.5 to 9 nm, and particularly 3 to 7 nm. This is preferred because colloidal silica having an average particle size of less than 2 nm may increase the viscosity of the coating solution, resulting in a longer manufacturing time for the photographic paper or the requirement to include an expensive viscosity depressant in the coating composition.

[0010] The outermost layer preferably contains 10 mg / m 2 ~260 mg / m 2 , more preferably 40 mg / m 2 ~225 mg / m 2 , particularly about 150 mg / m 2 of colloidal silica. The photographic paper of the present invention has a low tendency to stick or no tendency to stick and can be conveniently produced at a high speed exceeding 200 m / min, for example, using a slide coater or a curtain coater.

[0011] The function of the outermost layer of the present invention is to reduce the noise generated when turning, bending, and / or moving the pages of the photographic paper in the photo book. Therefore, the outermost layer generally does not contain silver halide.

[0012] The colloidal silica preferably consists essentially of silicon dioxide. Optionally, the colloidal silica can contain alumina or sodium aluminate as trace components, for example, in an amount of 0 to 0.1 g per 1 g of silicon dioxide. The colloidal silica can optionally contain an inorganic base, such as sodium hydroxide, potassium hydroxide, lithium hydroxide or ammonia, or an organic base, such as a tetraethylammonium salt, as a stabilizer.

[0013] The colloidal silica can be used in the form of a colloidal dispersion of silica fine particles in a medium such as water or an organic liquid, for example, methanol, ethanol, propanol, butanol, acetone, ethyl acetate or butyl acetate.

[0014] Preferred in the present invention is the use of a silicate sol or a silica sol in an aqueous environment. However, when calculating the weight ratio of the colloidal silica to the hydrophilic colloid binder, the weights of other components (such as water, organic liquids, etc.) are not taken into account.

[0015] Examples of commercially available products containing colloidal silica include Levasil from H.C. Starck TM 300 and Levasil TM 500. According to the manufacturer's catalog, these products contain colloidal silica with average particle sizes of 9 nm and 6 nm, respectively, and surface areas of 300 g / m 2 and 450 g / m 2 respectively. Bindzil TM 30 / 360 can also be used (7 nm). Other commercially available colloidal silicas include NexSil from Nyacol Nano Technologies, Inc TM 5 (6 nm) and NexSil TM8 (8 nm) can be mentioned. The colloidal silica can be surface-treated as necessary.

[0016] Preferably, the weight ratio of the colloidal silica to the hydrophilic colloid binder in the outermost layer is (0.06 to 0.10) to (0.13 to 0.27). We have found that the outermost layer provides a photographic paper having a silk finish, a raster finish or a matte finish with much less noise when used in a photo book without impairing the physical appearance of the supported image. Further, since the viscosity of the composition required to bring about the above colloidal silica usage amount is generally sufficiently low at high shear, in one step of the multilayer coating method, for example, a slide coater or a curtain coater can be used to apply it to a base layer carrying one or more photosensitive emulsion layers at a speed faster than 150 m / min. It is even possible to achieve a speed faster than 200 m / min (i.e., for example, 300 m / min or 350 m / min).

[0017] The photographic paper of the present invention also has good writability. In other words, the paper accepts subsequent marking with ink and even a pencil. The hydrophilic colloid binder is preferably gelatin or contains gelatin. Preferred gelatins include acid-treated gelatin, a mixture containing acid-treated gelatin and alkali-treated gelatin, and optionally other hydrophilic binders.

[0018] Preferred acid-treated gelatin includes gelatin produced by treating collagen with hydrochloric acid or the like, which is different from typical alkali-treated gelatin used in the photographic industry. Details of the production processes and properties of acid- and alkali-treated gelatin are described in Arthus Veis, The Macromolecular Chemistry of Gelatin, pages 187-217, Academic Press (1964). Preferred acid-treated gelatin has an isoelectric point at a pH of about 6.0-9.5, while alkali-treated gelatin typically has an isoelectric point at a pH of about 4.5-5.3.

[0019] The hydrophilic colloid binder preferably includes acid-treated gelatin and a further hydrophilic binder other than acid-treated gelatin, such as alkali-treated gelatin, enzyme-treated gelatin or a gelatin derivative. Gelatin derivatives can be prepared by treating and modifying the functional groups contained in gelatin molecules with chemicals other than simple acids and alkalis. For example, the amino, imino, hydroxyl or carboxyl groups normally present in gelatin can be reacted with a compound having a group capable of reacting with such a functional group. To prepare a gelatin derivative, a polymer or another high molecular weight material may be grafted onto gelatin. Compounds having a group capable of reacting with the functional groups in gelatin include, for example, isocyanates, acid chlorides and acid anhydrides as described in U.S. Patent No. 2,614,928; acid anhydrides as described in U.S. Patent No. 3,118,766; bromoacetic acid; phenyl glycidyl ether; vinyl sulfone compounds as described in U.S. Patent No. 3,132,945; N-allyl vinyl sulfone amide as described in British Patent No. 861,414; maleimide compounds as described in U.S. Patent No. 3,186,846; acrylonitrile as described in U.S. Patent No. 2,594,293; polyalkylene oxides as described in U.S. Patent No. 3,312,553; epoxy compounds; acid esters as described in U.S. Patent No. 2,763,639; alkanesulfones as described in British Patent No. 1,033,189; and the like.

[0020] Furthermore, suitable hydrophilic colloid binders include proteins such as colloidal albumin and casein; cellulose derivatives such as carboxymethyl cellulose and hydroxyethyl cellulose; polysaccharides such as agar, sodium alginate, dextran, gum arabic and starch derivatives; and synthetic hydrophilic colloids such as polyvinyl alcohol, poly-N-vinylpyrrolidone, polyacrylic acid copolymers, polymethacrylic acid copolymers, polyacrylamide and polymethacrylamide; and mixtures and derivatives thereof. If desired, compatible mixtures containing two or more of these hydrophilic colloid binders can be used. Among the above hydrophilic colloid binders, gelatin derivatives and synthetic high molecular weight materials having a carboxyl group or a salt thereof are particularly preferred.

[0021] There are no special restrictions on the mixing ratio of the treated gelatin and the other hydrophilic colloid binders described above. However, in order to obtain particularly good results, the hydrophilic colloid binder preferably contains at least 20% by weight, more preferably at least 40% by weight of the acid-treated gelatin. When the hydrophilic colloid binder contains at least 20% by weight of the acid-treated gelatin and is less than about 20% by weight and no alkaline-treated gelatin, enzyme-treated gelatin or gelatin derivative is present as part of the hydrophilic colloid binder, the composition used to apply the outermost layer to the substrate cures (solidifies) particularly well, increasing the likelihood of resulting in a uniformly smooth coated surface.

[0022] The outermost layer preferably contains 0.2 to 1.5 g / m 2 of the hydrophilic colloid binder. The photographic paper of the present invention preferably contains 4 to 10 g / m 2 preferably 5 to 8 g / m 2 of the hydrophilic colloid binder.

[0023] If desired, the outermost layer contains one or more additional constituents such as a matting agent, a curing agent, a lubricant, a surfactant and / or a pH adjuster. Examples of suitable matting agents include certain organic compounds such as water-dispersible vinyl polymers such as methyl polyacrylate, polymethyl methacrylate and / or polystyrene, and certain inorganic compounds such as silver halide, strontium barium sulfate, magnesium oxide and / or titanium oxide.

[0024] In a particularly preferred embodiment, the outermost layer further comprises polymethyl methacrylate (PMMA), especially PMMA having an average diameter of 3 to 10 microns (e.g., 4 microns), preferably in an amount of 2 to 50 mg / m 2 (e.g., 10 mg / m 2 ).

[0025] As lubricants, for example, waxes, liquid paraffin, higher fatty acid esters, polyfluorinated hydrocarbons or their derivatives, polysiloxanes such as polyalkylpolysiloxanes, polyarylsiloxanes, polyalkylarylphenylpolysiloxanes and / or their alkylene oxide adducts can be used.

[0026] In one aspect, the outermost layer contains one or more curing agents. Such curing agents can be included to enhance the physical strength of the outermost layer. Specific examples of suitable curing agents include aldehyde compounds such as formaldehyde and glutaraldehyde; ketone compounds such as diacetyl and cyclopentanedione; compounds containing reactive halogen such as bis(2-chloroethylurea) and 2-hydroxy-4,6-dichloro-1,3,5-triazine; compounds described in U.S. Patent Nos. 3,288,775, 2,732,303, British Patent Nos. 974,723 and 1,167,207; reactive olefin compounds such as divinyl sulfone, 5-acetyl-1,3-diacryloylhexahydro-1,3,5-triazine and compounds described in U.S. Patent Nos. 3,635,718, 3,232,763 and British Patent No. 994,869; N-methylol compounds such as N-hydroxymethylphthalimide and compounds described in U.S. Patent Nos. 2,732,316 and 2,586,168; isocyanates such as those described in U.S. Patent No. 3,103,437; aziridine compounds such as those described in U.S. Patent Nos. 3,017,280 and 2,983,611; acid derivatives described in U.S. Patent Nos. 2,725,294 and 2,725,295; carbodiimide compounds such as those described in U.S. Patent No. 3,100,704; epoxy compounds such as those described in U.S. Patent No. 3,091,537; isoxazole compounds such as those described in U.S. Patent Nos. 3,321,313 and 3,543,292; halocarboxyaldehyde such as mucobromic acid; dioxane derivatives such as dihydroxydioxane and dichlorodioxane; and inorganic curing agents such as chrome alum and zirconium sulfate. Further, instead of the above compounds, curing agent precursors such as alkali metal bisulfite-aldehyde adducts, methylol derivatives of hydantoin, and primary aliphatic nitroalcohols can be used. Particularly preferred curing agents are 1-oxy-3,5-dichloro-s-triazine and its salts such as the sodium salt.

[0027] The ratio (R) of the hardener to the fully hydrophilic colloid binder preferably satisfies the following formula: R = (Hmol / HCg) [where: R is greater than 0.00013; Hmol is the total number of moles of the hardener; and HCg is the weight in grams of the hydrophilic colloid binder].

[0028] The above preference for R applies especially when the outermost layer contains the hardener. Although the above preference is stated with respect to the outermost layer, it is also preferred that the entire photographic paper (i.e., not just the outermost layer) has the ratio (R) of the hardener to the hydrophilic colloid binder as defined above.

[0029] In the above formula, the weight of the hydrophilic colloid binder is in grams on a 100% solids basis. For example, when the hydrophilic colloid binder is gelatin, which is preferred, the weight of water present in the binder is not included when calculating the weight of the hydrophilic colloid binder in grams. The weight of the hydrophilic colloid binder on a 100% solids basis can be calculated, for example, by drying to remove water or organic solvent to find the concentration and multiplying that concentration by the amount used.

[0030] Preferably, R has a value of 0.00014 to 0.00018. When R has the above value, the resulting photographic paper often benefits from an improved ability to be peeled from a sheet of another photographic paper without significantly damaging the image after being stored together in a face-to-face manner. We refer to this as "improved peeling behavior".

[0031] Surfactants can also be included in the outermost layer, individually or as mixtures thereof, for example, in an amount of about 0.5 to 50 mg, preferably 1 to 20 mg per gram of the hydrophilic colloidal binder. These are generally used as coating aids to prevent problems such as coating unevenness, but may also be used for other purposes, such as improving emulsification and dispersion, preventing the formation of static charges, etc. These surfactants include, for example, natural surfactants such as saponin; nonionic surfactants, such as alkylene oxide, glycerol, and glycidol nonionic surfactants; cationic surfactants, such as higher alkylamines, quaternary ammonium salts, pyridinium and other heterocyclic onium salts, phosphonium and sulfonium; anionic surfactants containing acid groups, such as carboxylic acid, sulfonic acid, phosphoric acid, sulfuric acid ester or phosphoric acid ester groups; and amphoteric surfactants, such as amino acids, aminosulfonic acids, or sulfuric acid esters or phosphoric acid esters of amino alcohols, etc.; and can be classified as such.

[0032] Surfactants that can be used are described, for example, in U.S. Pat. Nos. 2,271,623; 2,240,472; 3,441,413; 3,442,654; 3,475,174; and 3,545,974; German Patent Application (OLS) No. 1,942,665; and British Patents Nos. 1,077,317 and 1,198,450, in addition to Ryohei Oda et al., Synthesis and Applications of Surface Active Agents, Maki Publisher (1964), A.M. Schwartz et al., Surface Active Agents, Interscience Publications In. (1958), and J.P. Sisley et al., Encyclopedia of Surface Active Agents, Vol. 2, Chemical Publishing Company (1964).

[0033] The photographic paper of the present invention may contain the following components if desired and can be produced by the following production method. The silver halide emulsion for the photosensitive emulsion layer (one or more) is usually prepared by mixing a solution of a water-soluble silver salt (such as silver nitrate) with a solution of a water-soluble halide (such as potassium bromide or sodium chloride) in the presence of a solution of a water-soluble high molecular weight material such as gelatin. Examples of silver halides that can be used include silver chloride, silver bromide, and mixed silver halides such as silver chlorobromide, silver bromoiodide, or silver chlorobromoiodide. The silver halide grains can be prepared using conventional methods. Needless to say, the grains can be advantageously prepared using, for example, the so-called single or double jet method, the controlled double jet method, etc. Further, two or more separately prepared silver halide photographic emulsions can be mixed as necessary.

[0034] The crystal structure of the silver halide grains can be uniform throughout the grains if desired, can have a layered structure with different internal and external layers, or can be of the so-called conversion type as described in British Patent No. 635841 and U.S. Patent 622318. Also, the silver halide can be of the type in which a latent image is mainly formed on the surface of the grains, or can be of the type in which a latent image is formed inside the grains.

[0035] The above photographic emulsion is described, for example, in C.E.K. Mees & T.H. James, The Theory of the Photographic Process, 3rd Ed., Macmillan, New York (1966); P. Grafkides, Chimie Photographique, Paul Montel, Paris (1957); etc., and can be prepared using various commonly used methods such as the ammonia process, the neutral process, or the acidic process.

[0036] Particularly preferred are silver halide grains such as those prepared and described in U.S. Patent No. 6,949,334. After formation, the silver halide grains are washed with water to remove water-soluble salts (e.g., potassium nitrate when preparing silver bromide using silver nitrate and potassium bromide) that occur as by-products from the system, and then heat-treated in the presence of a chemical sensitizer such as sodium thiosulfate, N,N,N'-trimethylthiourea, gold(I) thiocyanate complex, gold(I) thiosulfate complex, stannous chloride or hexamethylenetetramine to increase the sensitivity without coarsening the grains. Conventional sensitization methods are described in the above Mees and James, as well as the above Grafkides.

[0037] Hydrophilic colloids that can be used as vehicles for silver halide include gelatin, colloidal albumin, casein, cellulose derivatives such as carboxymethyl cellulose or hydroxyethyl cellulose, polysaccharides such as agar, sodium alginate or starch derivatives, and synthetic hydrophilic colloids such as polyvinyl alcohol, poly-N-vinylpyrrolidone, polyacrylic acid copolymers or polyacrylamides, and their derivatives, and their partially hydrolyzed products. If desired, a compatible mixture of two or more of these hydrophilic colloids can be used. Among the above hydrophilic colloids, gelatin is most commonly used, but gelatin can be replaced, in part or completely, with synthetic high molecular weight materials. Further, gelatin can be replaced, for example, with so-called gelatin derivatives as described above.

[0038] In the photographic emulsion layer(s) and other layers that can be used in the present invention, synthetic polymer compounds such as latexes of water-dispersible vinyl compound polymers, particularly compounds that improve the dimensional stability of photographic materials, can be incorporated by themselves, or as mixtures (e.g., of different polymers), or in combination with hydrophilic colloids that exhibit water permeability. Many such polymers are known and are described, for example, in U.S. Patent Nos. 2,375,005, 3,607,290, and 3,645,740, British Patent Nos. 1,186,699 and 1,307,373, etc. Among these polymers, copolymers or homopolymers of alkyl acrylates, alkyl methacrylates, acrylic acid, methacrylic acid, sulfoalkyl acrylates, sulfoalkyl methacrylates, glycidyl acrylate, glycidyl methacrylate, hydroalkyl acrylates, hydroxyalkyl methacrylates, alkoxyalkyl acrylates, alkoxy methacrylates, styrene, butadiene, vinyl chloride, vinylidene chloride, maleic anhydride, and itaconic anhydride are generally used. If necessary, so-called graft-type emulsion polymerization latexes of these vinyl compounds, which are prepared by emulsion polymerization of such vinyl compounds in the presence of a hydrophilic protective colloid high molecular weight material, can be used.

[0039] The photographic paper of the present invention generally contains one or more photosensitive silver halide emulsion layers between the outermost layer and the base layer. The silver halide emulsion layer(s) can be sensitized by conventional methods. Suitable chemical sensitizers include, for example, gold compounds such as chloroaurate or auric trichloride as described in U.S. Patent Nos. 2,399,083; 2,540,085; 2,597,856; 2,597,915; and 6,949,334; salts of noble metals such as salts of platinum, palladium, iridium, rhodium, or ruthenium as described in U.S. Patent Nos. 2,448,060; 2,540,086; 2,566,245; 2,566,263; 2,598,079; and 6,949,334, and sulfur compounds that can form silver sulfide by reacting with silver salts as described in, for example, U.S. Patent Nos. 1,574,944; 2,410,689; 3,189,458; and 3,501,313; stannous salts such as those described in U.S. Patent Nos. 2,487,850 and 2,518,698; amines; and other reducing compounds. Preferred techniques are gold sensitization, sulfide, and / or iridium sensitization as described using general formula (i) on page 12 of U.S. Patent No. 6,949,334. In the case of gold sensitization, if desired, various inorganic gold compounds or gold(I) complexes having inorganic ligands, and gold(I) compounds having organic ligands can be used.

[0040] Regarding inorganic gold compounds, for example, chloroauric acid or its salts can be used. Among gold(I) complexes having inorganic ligands, for example, gold dithiocyanate compounds such as potassium gold(I) dithiocyanate and gold dithiosulfate compounds such as trisodium gold(I) dithiosulfate can be used.

[0041] Furthermore, the gold(I) thiolate compounds described in U.S. Patent No. 3,503,749, JP-A-8-69074, JP-A-8-69075, and JP-A-9-269554, and the gold compounds described in U.S. Patent Nos. 5,620,841, 5,912,112, 5,620,841, 5,939,245, and 5,912,111 can also be used.

[0042] During the production, storage, and processing of photographic paper, various compounds can be added to the emulsion layer(s) of the photographic paper to prevent a decrease in sensitivity and the occurrence of fog. Many such compounds are known, for example, 4-hydroxy-6-methyl-1,3,3a,7-tetraazaindene, 3-methylbenzothiazole, 1-phenyl-5-mercaptotetrazole, 5-arylamino-1,2,3,4-thiatriazole, as well as numerous heterocyclic compounds, mercury-containing compounds, mercapto compounds, metal salts, and the like. Examples of such compounds that can be used are described in the above C.E.K. Mees & T.H. James and the original references cited therein, and further in the following patent documents: U.S. Patent Nos. 1,758,576, 2,110,178, 2,131,038, 2,173,628, and British Patent Nos. 893,428, 403,789, 1,173,609, and 1,200,188 and European Patent No. 447,647. As particularly preferred for improving the storability of silver halide emulsions, the following compounds are also preferably used in the present invention: hydroxamic acid derivatives described in JP-A-11-109576, cyclic ketones in which both ends of a double bond adjacent to a carbonyl group are substituted with an amino group or a hydroxyl group (especially those represented by the general formula (S1); the description in paragraphs 0036 to 0071 can be incorporated herein), sulfo-substituted catechols or hydroquinones described in JP-A-11-143011 (for example, 4,5-dihydroxy-1,3-benzenedisulfonic acid, 2,5-hydroxy-1,4-benzenedisulfonic acid, 3,4-dihydroxybenzenesulfonic acid, 2,3-dihydroxybenzenesulfonic acid, 2,5-dihydroxybenzenesulfonic acid, 3,4,5-trihydroxybenzenesulfonic acid and their salts), hydroxylamines represented by the general formula (A) in the specification of U.S. Patent No. 5,556,741 (the description in columns 4 to 11 of the specification of U.S. Patent No. 5,556,741 can also be preferably applied in the present invention and incorporated as part of the specification of this application), and water-soluble reducing agents represented by the general formulas (I) to (III) in JP-A-11-102045.

[0043] The photosensitive emulsion layer(s) can be spectrally sensitized or supersensitized, if necessary, using cyanine dyes such as cyanine, merocyanine or carbocyanine, individually, or in combination, or in combination with, for example, styryl dyes. Such color sensitization techniques are known in the art.

[0044] The photosensitive emulsion layer can be cured using a curing agent, if desired. Examples of suitable curing agents are given above. The emulsion layer(s) contain(s) a surfactant, if desired, individually or in combination.

[0045] Preferably, the base layer has a silky, raster or matte appearance. The base layer preferably has a specular gloss of less than 60%, more preferably 20 - 50%, when measured at an angle of 60 degrees by the method of JIS Z8741.

[0046] Preferably, the base layer includes paper, particularly laminated paper. The base layer preferably includes structured laminated paper. The base layer preferably includes a plurality of pits and / or peaks. In this way, the base layer has a non-glossy appearance (e.g., a silky, raster, or matte appearance). A suitable base layer (e.g., a base layer having a desired specular gloss, roughness, pits, structure, or lamination) can be obtained, for example, by extrusion coating a polymer onto a paper base layer. The extrusion material (i.e., the polymer), typically in the form of granules, particles, or powder, can be compressed, melted, and homogenized in an extruder. The molten extrusion material can then be applied to the paper substrate by an extrusion die adapted to the width of the paper web. The paper may be pretreated to achieve good bond strength with the polymer. Flame pretreatment, corona treatment, ozone shower, or primer application can also be used to improve the adhesion of the polymer to the paper. Thereafter, the extruded polymer film can be cooled by a chill roll. The surface profile of this chill roll also has a significant impact on the surface of the resulting base layer, and a surface roller with a rough surface profile can be used to obtain a base layer having a desired roughness, specular gloss, etc.

[0047] The structure of the surface of the base layer can be made "highly structured" (i.e., less glossy and rougher) in a controlled manner by simply selecting a chill roll having a desired surface profile. The structured surface of the resulting base layer is a mirror image of the surface of the chill roll.

[0048] A chill roll having a rough surface profile can be brought about by chrome plating the chill roll body and then sandblasting the chrome surface to create surface roughness. This forms a large number of usually very fine recesses on the surface of the chill roll. Depending on the type and size of the sandblasting material and the processing time, a silky, raster, or matte surface can be obtained.

[0049] Accordingly, the base layer preferably includes a paper substrate and a polymer, and the polymer is bonded to the paper and provides a textured surface profile thereon. The base layer preferably has an average surface roughness (Sa) of 0.9 to 5 μm, more preferably 1.0 to 4 μm, and particularly 1.1 to 3.9 μm.

[0050] The preferred base layer is not a glossy photographic paper derived from a glossy support, and generally does not generate noise when turned in a photo album, and has, for example, a silk, raster or matte finish. The base layer may be coated or laminated, if desired, with a synthetic resin film having a polymer of an alpha-olefin, especially an alpha-olefin having 2 to 10 carbon atoms, such as polyethylene, polypropylene, ethylene-butene copolymer, etc., or having a roughened surface to improve the adhesion to other high molecular weight materials and the printability. If necessary, the lamination of the polymer on the paper is carried out through a multilayer having a pigment in the intermediate polymer layer using coextrusion technology.

[0051] The preferred base layer is a photographic grade base paper laminated with polyethylene resin on one or both sides as desired, and the ratio of the resin weight on the upper surface to the resin weight on the back surface is preferably in the range of 0.70:1 to 1.30:1, and even more preferably in the range of 0.85:1 to 1.15:1.

[0052] The base layer preferably has a thickness of 70 to 250 microns (for example, 130 or 147 or 160 or 227 microns). The base layer can be further colored with a dye or pigment, if necessary.

[0053] If the adhesion between the base layer and the photosensitive emulsion layer(s) is insufficient, a layer having good adhesion to both of these elements can be employed as an undercoat layer. In order to further improve the adhesion characteristics of the base layer, the surface of the base layer can be pretreated by corona discharge, ultraviolet irradiation, ozone treatment, flame treatment, etc.

[0054] Examples of paper-based layers commercially available from Schoeller having the required surface roughness Sa (μm) and standard deviation SD (μm) include the raster paper, matte paper, and pyramid paper (obtained from Schoeller) described in Table 1 below:

[0055]

Table 1

[0056] In Table 1: Sa means the surface roughness in μm. Laminated top surface (g / m 2 ) means the amount of polyethylene in g / m laminated on the top surface of the base paper 2 .

[0057] Laminated bottom surface (g / m 2 ) means the amount of polyethylene in g / m laminated on the top surface of the base paper 2 . The average surface roughness (Sa) of the base layer can be measured by the method of ISO 25178-1-2016, for example, using an interference method. Sa can be determined by calculating the arithmetic mean of the absolute values of all height values z in the x, y plane of the field area between the measurement points. In each case, three measurements can be carried out, and the average value of the individual measurements is given in μm. A device suitable for measuring the average surface roughness (Sa) is a Bruker Contour GT-K 3D profilometer combined with the "Vision 64" software. A 2 mm × 2 mm area of the paper-based layer can be observed at a magnification of 10.9 times, optionally using the conditions described in the following examples if desired.

[0058] The outermost layer and the photosensitive emulsion layer(s) (one or more) can be applied to the base layer by any suitable technique including dip coating, air knife coating, curtain coating, and extrusion coating. If desired, two or more layers can be coated simultaneously using the techniques described in U.S. Patent Nos. 2,761,791; 3,508,947; 2,941,898; and 3,526,528.

[0059] The outermost layer and the underlying photosensitive emulsion layer(s) (one or more) are preferably applied simultaneously to the base layer using a slide coater or a curtain coater, preferably at a coating speed faster than 200 m / min.

[0060] The photographic paper may further include, if desired, an intermediate layer, a filter layer, an undercoat layer, an antihalation layer, and the like. The photographic paper of the present invention can be developed after exposure to form a color image, often resulting in what is commonly referred to as a photograph. The developing process can include several steps (e.g., a combination of bleaching, fixing, bleach-fixing, stabilizing, washing, etc.) and can be carried out at a temperature of less than about 20°C, or at a higher temperature, and, if desired, above about 30°C, preferably about 32°C to 60°C. Again, these steps do not necessarily have to be carried out at the same temperature and can be carried out at a higher or lower temperature.

[0061] The color developer contains a compound in which an oxidation product reacts with a color former to form a dye, that is, as a developer, p-phenylenediamine such as N,N-diethyl-p-phenylenediamine, N,N-diethyl-3-methyl-p-phenylenediamine, 4-amino-3-methyl-N-ethyl-N-methanesulfonamidoethyl aniline, 4-amino-3-methyl-N-ethyl-N-beta-hydroxyethyl aniline and N-ethyl-N-beta-hydroxyethyl-p-phenylenediamine, or salts thereof such as their hydrochlorides, sulfates and sulfites, and is an alkaline aqueous solution. The alkaline aqueous solution has a pH higher than about 8, preferably 9 to 12. Compounds as described in U.S. Patent Nos. 2,193,015 and 2,592,364 can also be used as developing agents. In addition to the above developing agents, the color developer can contain salts such as sodium sulfate; pH adjusters such as sodium hydroxide, sodium carbonate or sodium phosphate; buffers such as acids such as acetic acid or boric acid, or salts thereof; and development accelerators such as various pyridinium compounds, cationic compounds, potassium nitrate and sodium nitrate described in U.S. Patent Nos. 2,648,604 and 3,671,247, polyethylene glycol condensates and derivatives thereof described in U.S. Patent Nos. 2,533,990, 2,577,127 and 2,950,970, nonionic compounds such as polythioethers represented by the compounds described in British Patent Nos. 1,020,033 and 1,020,032, polymer compounds containing sulfite groups represented by the compounds described in U.S. Patent No. 3,068,097, and organic amines such as pyridine or ethanolamine, benzyl alcohol, hydrazine, etc.Furthermore, the color developer may contain antifoggants such as alkali metal bromides, alkali metal iodides, nitrobenzimidazole described in U.S. Patent Nos. 2,496,940 and 2,656,271, mercaptobenzimidazole, 5-methylbenzotriazole, 1-phenyl-5-mercaptotetrazole, compounds for rapid processing described in U.S. Patent Nos. 3,113,864, 3,342,596, 3,295,976, 3,615,522 and 3,597,199, thiosulfonyl compounds described in British Patent No. 972,211, phenazine-N-oxide, antifoggants described on pages 29-47 of Manual of Scientific Photography, Vol. 2; contamination or sludge inhibitors described in U.S. Patent Nos. 3,161,513 and 3,161,514 and British Patent Nos. 1,030,442, 1,144,481 and 1,251,558; accelerators for interimage effects described in U.S. Patent No. 3,536,487; and antioxidants such as sulfites, bisulfites, hydroxylamine hydrochloride or formaldehyde-alkanolamine sulfite adducts.

[0062] All of the additives exemplified for each of the above processing steps and their amounts of use are known in the technical field of color photographic processing methods. After color development, photographic paper is usually bleached and fixed. Bleaching and fixing may be combined, and thus a bleach-fixing bath may be used. Many compounds can be used as bleaching agents. Among these compounds, generally, ferricyanide salts, dichromates, water-soluble iron(III) salts, water-soluble cobalt(III) salts, water-soluble copper(II) salts, water-soluble quinones, nitrosophenols, complex salts of organic acids with polyvalent cations such as iron(III), cobalt(III) or copper(II) (for example, metal complexes of aminopolycarboxylic acids such as ethylenediaminetetraacetic acid, nitrilotriacetic acid, iminodiacetic acid or N-hydroxyethylethylenediaminetriacetic acid, malonic acid, tartaric acid, malic acid, diglycolic acid, or dithioglycolic acid, copper(II) 2,6-dipicolinate complex salt), alkylperoxy acids, peroxo acids such as persulfates, permanganates or hydrogen peroxide, hydrochlorides, chlorine, bromine, etc. are used individually or in suitable combinations. In addition, bleach accelerators described in U.S. Patent Nos. 3,042,520 and 3,241,966 etc. can also be used.

[0063] In the fixing step, any known fixing solution can be used. For example, ammonium thiosulfate, sodium thiosulfate or potassium thiosulfate can be used as a fixing agent in an amount of about 50 to 200 g / liter. In addition, stabilizers such as sulfites or metabisulfites, hardeners such as potassium alum, pH buffers such as acetates or borates, etc. can be present in the fixing solution. The fixing solution has a pH of about 3 to 12, usually about 3 to 8.

[0064] Suitable bleaching agents, fixing agents and bleach-fixing baths are described, for example, in U.S. Patent No. 3,582,322. An image stabilizing bath can also be used according to techniques such as those described in U.S. Patent Nos. 2,515,121, 2,518,686, and 3,140,177.

[0065] As described in U.S. Patent No. 6,949,334, appropriate processing steps can also be used, such as utilizing a low replenishment rate at a short latent image time within 12 seconds after exposure of the printing paper by laser (digital) scanning.

[0066] According to a second aspect of the present invention, there is provided a method for producing a printing paper, which comprises applying a composition to a base layer having an average surface roughness (Sa) of at least 0.7 μm and one or more photosensitive emulsion layers, wherein the composition comprises a hydrophilic colloid binder and colloidal silica in a weight ratio of 0.05:1 to 0.28:1; the amount of colloidal silica provided by the composition is in the range of 8 mg / m 2 ~280 g / m 2 of colloidal silica.

[0067] In this method, the composition is preferably applied to the outermost photosensitive emulsion layer at a coating speed faster than 200 m / min, more preferably faster than 300 m / min.

[0068] The composition is preferably applied to the outermost photosensitive emulsion layer using a slide coater or a curtain coater. In a preferred embodiment, the composition and at least one photosensitive emulsion layer (preferably at least three photosensitive emulsion layers) are simultaneously applied to the base layer, optionally together with the above composition (forming the outermost layer).

[0069] The composition preferably comprises a liquid medium, a hydrophilic colloid binder and colloidal silica in a weight ratio of 0.05:1 to 0.28:1 (preferably 0.06 to 0.10) to (0.13 to 0.27), and preferably the colloidal silica has an average particle size of 2.5 to 9 nm. Typical liquid media include water and mixtures comprising water and one or more water-miscible organic solvents.

[0070] The composition preferably has a viscosity of 30 to 75 cP, more preferably 40 to 60 cP, at 20°C. In one aspect, the photographic paper further contains a curing agent and a hydrophilic colloid binder at a ratio (R) that satisfies the following formula: R=(Hmol / HCg) [wherein: R is greater than 0.00013; Hmol is the total number of moles of the curing agent in the photographic paper; and HCg is the weight in grams of the hydrophilic colloid binder in the photographic paper].

[0071] The method preferably further includes a step of drying the composition after applying the composition to the base layer. According to a third aspect of the present invention, there is provided an album book including one or more photographs including the photographic paper according to the first aspect of the present invention.

[0072] To fully utilize the advantages of the present invention, the album book preferably includes at least two of the photographs arranged such that the photographs are in face-to-face contact when the album book is closed. Usually, there is no need to include an interleaving foil separating the surfaces of the photographs, but if desired, such an interleaving foil may be included.

Examples

[0073] The present invention will be further described by referring to the following non-limiting examples. Unless otherwise indicated herein, all parts, percentages, ratios, etc. are by weight. In the examples, the average surface roughness (Sa) of the base layer was measured using a Bruker Contour GT-K 3D profilometer combined with "Vision 64" software set as follows (no Pt coating was required):

[0074]

Table 2

[0075] The average surface roughness (Sa) means the average roughness (in μm) determined by filtering using the above interferometer and software. The base layers used in the examples had the properties described in Table 2 below:

[0076]

Table 3

[0077] In Table 2, Sa, the upper surface of the laminate (g / m 2 ) and the lower surface of the laminate (g / m 2 ) have the meanings described above in relation to Table 1. All of the base layers were obtained from Schoeller under the names shown in the first and third columns of Table 2.

[0078] In the following experiments, a base layer having an average surface roughness (Sa) of at least 0.7 μm was regarded as "rough". Quantification of Noise (Noise Test) The squeak test was conducted as follows: The intensity of the squeak is directly related to the amplitude of the coefficient of friction (COF) in relative motion.

[0079] This COF was measured using a friction tester (Thwing-Albert FP-2260). A first test print paper piece with dimensions of 100 mm × 250 mm was placed on a plane. A weight with a square base of 0.4 Kg in mass and dimensions of 6.4 cm × 6.4 cm, having a second print paper piece on the bottom surface, was dragged along the first print paper piece at a speed of 10 mm / min. The first 20 mm was mainly dominated by static friction, and after that, the steady motion after 20 mm was dominated by the coefficient of kinetic friction. Therefore, the first print paper piece (attached to the bottom of the weight) and the second print paper piece were in face-to-face contact. The noise generated was related to the amplitude of the coefficient of kinetic friction, which is directly related to the standard deviation.

[0080] A standard deviation exceeding 0.06 was regarded as "having noise" or "being noisy". In Table 4 below, a value of 0 indicates non - compliance (i.e., having noise due to a standard deviation exceeding 0.06), and a value of 1 indicates compliance (i.e., having no noise due to a standard deviation of 0.06 or less). Blocking Test Evaluation The degree to which various photographic papers adhered was evaluated by the following blocking test.

[0081] Samples of the developed photographic paper were each cut into 3.5 cm × 3.5 cm squares, and two squares of each developed photographic paper were overlapped with each other (facing). A 200 - g weight was placed on the two squares of the photographic paper and stored in a room adjusted to 52 °C and 85% relative humidity for 24 hours. Then, with the weight left as it was, the squares of the photographic paper were placed in a room adjusted to 25 °C and 60% relative humidity for 1 hour. The blocking (i.e., the degree to which the two facing squares adhered) of these developed photographic paper squares was evaluated by the following procedure: The two squares of the developed photographic paper were separated, and the level of damage to the contacting surface was scored as follows, with 5 being the most severe damage and 1 indicating that the damage was not detectable: 5: Severe damage: The base layer of the developed photographic paper was completely torn, resulting in a completely unacceptable level of damage. 4: Damage: Approximately 50% of the base layer of the developed photographic paper was torn, and the emulsion layer was damaged, resulting in a very poor and unacceptable result. 3: The base layer of the developed photographic paper was not torn. However, the emulsion layer suffered visible damage, resulting in an insufficient and unacceptable result. 2: The base layer of the developed photographic paper was not torn. The damage to the emulsion was not detectable by the naked eye but was visible under a microscope. This was regarded as a good result. 1: The base layer of the developed photographic paper was not torn even when using a microscope, and no damage to the emulsion layer was detected. This was regarded as a very good result. Examples The four base layers described in Table 2 above (LR-pyramid, LR-raster, LR-mat, and LR-glossy, all manufactured by Schoeller) were each coated with seven emulsion layers in one step using a slide coater operating at a speed of 300 m / min. The first six emulsion layers were the same in each case and were as described below. However, the outermost (seventh) layer was varied as described in Table 3 below in order to compare the performance of the photographic paper containing the outermost layer according to the present invention with a comparative photographic paper outside the scope of the claims.

[0082] The silica used in the examples and comparative examples was colloidal silica obtained from H.C. Starck under the trade name Levasil TM The hardener used in the examples and comparative examples was sodium 1-oxy-3,5-dichloro-s-triazine.

[0083] The following dyes (coating amounts in parentheses) were included in the layer when indicated.

[0084]

Chemical formula

[0085] Layer Configuration The composition of each layer is shown below. The numbers indicate the coating amount (g / m 2 ). In the case of a silver halide emulsion, the coating amount is in terms of silver.

[0086]

Table 4

[0087]

Table 5

[0088]

Table 6

[0089]

Table 7

[0090]

Table 8

[0091]

Table 9

[0092] Seventh Layer (Outermost Layer) Fifty-six compositions were prepared by mixing the components shown in Table 3 below (i.e., eight compositions A - H each independently contained one of the seven colloidal silicas shown in the last row, resulting in a total of 8×7 = 56 compositions). These 56 compositions were then applied to the respective sixth layers above the base layer such that the resulting outermost layer contained the amounts of hydrophilic colloid binder and colloidal silica (g / m 2 unit) shown in Table 4 after drying. Thus, the outermost layer contained colloidal silica having an average particle size of 3, 9, 12, 17, 34, 70, or 100 nm, respectively. The compositions had a pH of 9.5 at 40 °C.

[0093]

Table 10

[0094] Results Various photographic papers containing the outermost layer derived from the 56 compositions listed in Table 3 were evaluated in the test described above as the "noise test" for the degree of noise generated when turned, bent, and / or moved in a photo book. The results are shown in Tables 4 - 9 below. 1 indicates "no noise" and 0 indicates "noise":

[0095]

Table 11

[0096]

Table 12

[0097]

Table 13

[0098] Results of Blocking Test The results of the blocking test were scored from 1 to 5 as described above. 1 represents the best result (the photographic paper was not damaged) and 5 represents the worst result:

[0099]

Table 14

[0100]

Table 15

[0101]

Table 16

[0102] The structural formulas of the compounds used in this specification are provided below: (ExY - 1): Yellow coupler

[0103] [Chemistry]

[0104] (ExM) Magenta color former (1), (2) and (3) 40:40:20 (molar basis) mixture:

[0105] [Chemistry]

[0106] [Chemistry]

[0107] [Chemistry]

[0108] [Chemistry]

[0109] [Chemistry]

[0110] [Chemistry] The present invention includes the following aspects. [1] A photographic paper comprising a base layer having an average surface roughness (Sa) of at least 0.7 μm and an outermost layer containing a hydrophilic colloidal binder and colloidal silica, (i) the weight ratio of colloidal silica to hydrophilic colloidal binder in the outermost layer is 0.05:1 to 0.28:1; and (ii) the amount of colloidal silica present in the outermost layer is in the range of 8 mg / m 2 ~280 mg / m 2 of the photographic paper. The photographic paper. [2] The photographic paper according to 1, wherein the base layer has a surface roughness (Sa) of 0.9 to 5 μm. [3] The photographic paper according to any one of 1 to 2, wherein the base layer has a specular gloss of less than 50% when measured at an angle of 60 degrees by the method of JIS Z8741. [4] The photographic paper according to any one of 1 to 3, wherein the base layer is a laminated paper support. [5] The photographic paper according to any one of 1 to 4, wherein the base layer contains a paper substrate and a polymer, and the polymer is bonded to the paper to provide a textured surface profile thereon. [6] The photographic paper according to any one of 1 to 5, wherein the colloidal silica has an average particle size of 2 to 70 nm. [7] The silky, raster, or matte photographic paper according to any one of 1 to 6. [8] A method for producing a photographic paper, comprising applying a composition to a base layer having an average surface roughness (Sa) of at least 0.7 μm and one or more photosensitive emulsion layers, the composition containing a hydrophilic colloidal binder and colloidal silica in a weight ratio of 0.05:1 to 0.28:1; the amount of colloidal silica provided by the composition being in the range of 8 mg / m 2 ~280 g / m 2 of colloidal silica, the method. [9] The method according to 8, wherein the composition further contains a curing agent and a hydrophilic colloidal binder in a ratio (R) that satisfies the following formula: R=(Hmol / HCg) [where: R is greater than 0.00013; Hmol is the number of moles of curing agent in the composition; and HCg is the weight in grams of the hydrophilic colloidal binder in the composition].[[]END]]

[10] The method according to 8 or 9, wherein the composition is applied to the base layer at a coating speed faster than 200 m / min.

[11] The method according to any one of 8 to 10, wherein the composition is applied to the base layer using a slide coater or a curtain coater.

[12] The method according to any one of items 8 to 11, wherein the composition and at least one photosensitive emulsion layer are simultaneously applied to a support.

[13] An album book containing one or more photographs including the photographic paper according to any one of items 1 to 7.

[14] The album book according to item 13, comprising at least two of the photographs arranged such that the photographs are in face-to-face contact when the album book is closed.

[15] The album book according to item 13 or 14, not including an interleaving foil.

Claims

1. A photographic paper comprising a base layer having an average surface roughness (Sa) of at least 0.7 μm and an outermost layer containing a hydrophilic colloidal binder and colloidal silica, wherein (i) the weight ratio of colloidal silica to hydrophilic colloidal binder in the outermost layer is from 0.05:1 to 0.28:1; (ii) The amount of colloidal silica present in the outermost layer is in the range of 8 mg / m ２ to 280 mg / m ２ and and (iii) the colloidal silica has an average particle size of 2 to 70 nm, said photographic paper.

2. The photographic paper according to claim 1, wherein the base layer has a surface roughness (Sa) of 0.9 to 5 μm.

3. The photographic paper according to any one of claims 1 to 2, wherein the base layer has a specular gloss of less than 50% when measured at an angle of 60 degrees by the method of JIS Z8741.

4. The photographic paper according to any one of claims 1 to 3, wherein the base layer is a laminated paper support.

5. The photographic paper according to any one of claims 1 to 4, wherein the base layer comprises a paper substrate and a polymer, and the polymer is bonded to the paper to provide a surface profile with a textured treatment thereon.

6. The average surface roughness (Sa) of the base layer is measured by the method of ISO 25178-1-2016, the photographic paper according to any one of claims 1 to 5.

7. The silky, raster, or matte photographic paper according to any one of claims 1 to 6.

8. A method for producing a photographic paper, comprising applying a composition to a base layer having an average surface roughness (Sa) of at least 0.7 μm and one or more photosensitive emulsion layers, wherein the composition contains a hydrophilic colloidal binder and colloidal silica in a weight ratio of 0.05:1 to 0.28:1; The amount of colloidal silica provided by the composition is in the range of 8 mg / m ２ to 280 g / m ２ of colloidal silica; and and the colloidal silica has an average particle size of 2 to 70 nm, said method.

9. The method according to claim 8, wherein the composition further contains a curing agent and a hydrophilic colloidal binder in a ratio (R) satisfying the following formula: R = (Hmol / HCg) wherein: R is greater than 0.00013; Hmol is the number of moles of the curing agent in the composition; and HCg is the weight in grams of the hydrophilic colloidal binder in the composition].

10. The method according to claim 8 or 9, wherein the composition is applied to the base layer at a coating speed faster than 200 m / min.

11. The method according to any one of claims 8 to 10, wherein the composition is applied to the base layer using a slide coater or a curtain coater.

12. The method according to any one of claims 8 to 11, wherein the composition and at least one photosensitive emulsion layer are simultaneously applied to a support.

13. An album book containing one or more photographs including the photographic paper according to any one of claims 1 to 7.

14. The album book according to claim 13, comprising at least two of said photographs arranged such that the photographs are in face-to-face contact when the album book is closed.

15. The album book according to claim 13 or 14, not including an interleaving foil.

Images