JPH0374812B2 - - Google Patents

Description

[Detailed description of the invention]

(A) Industrial Application Field The present invention relates to photographic paper, and more particularly to a method for improving the surface gloss of black and white photographic paper. (B) Prior art and its problems Photographic paper consists of at least one light-sensitive emulsion layer on an opaque support made of paper, baryta paper, polymer-laminated paper, polymer film with an opaque layer, etc. , a surface protective layer, and, if necessary, an intermediate layer, a filter layer, an undercoat layer, and a packing layer. Since the photographic image formed on the support of photographic paper is observed using reflected light, the quality of the image is greatly influenced by the reflection density of the image. As one means for increasing the reflection density of photographic paper, efforts have been made to increase the surface gloss of photographic paper. For example, a baryta layer, a polymer laminate layer, etc. is provided on the surface of the support, and then a photosensitive emulsion layer is applied thereon to improve the smoothness of the surface of photographic paper, thereby preventing scattering of incident light. , by increasing the surface gloss, or by drying the surface of the photographic paper after the development process by bringing it into contact with a heated metal plate (so-called ferro type), which has a mirror surface. Conventionally, methods of increasing the surface gloss by so-called ferrotype coating, methods of combining both methods, and the like have been well known. In recent years, photographic paper has become thinner as an energy-saving material, and with the thinning of the support, the photosensitive emulsion layer, surface protection layer, and other layers coated on the support have a tendency to become thinner at high or low humidity. At such times, thinning of the protective layer results in a decrease in surface gloss. Furthermore, in recent years there has been a demand for faster development processing.
For this reason, it is necessary to make the coating layer thinner, and maintaining and improving surface gloss has become an extremely important issue from that point of view as well. Japanese Patent Publication No. 56-24253 discloses a technique in which lime-treated gelatin with a jelly strength of 300 g or more is used as the top layer, but if the top layer is made thinner, its effect decreases, resulting in a decrease in gloss and an accompanying decrease in density. This leads to a decline in the commercial value of photographic paper.
Furthermore, in Japanese Patent Application No. 58-112491, a technology is proposed in which a desalinated lime-treated ossein gelatin layer with a jelly strength of 300 g or more and a calcium content of 1000 ppM or less is used as the top layer, but the photosensitive emulsion layer, surface protection As the layer becomes thinner, the gloss tends to decrease. On the other hand, in Japanese Patent Publication No. 57-10416, there is a technique in which colloidal silica is contained in the top layer and vinyl polymer is contained in the emulsion layer, but this technique cannot be expected to produce much gloss, and it is necessary to make the top layer thinner. As a result, the effect decreases, and furthermore, when colloidal silica is added to the top layer, the gloss of the white background of the photographic image decreases, making it undesirable for photographic printing paper. Half of a commonly used photographic print image is occupied by a white background area, which is an unexposed area, and a reduction in gloss in the white background area is unfavorable for the quality of the photographic printing paper. Furthermore, if the surface contains colloidal silica and is exposed, the surface of the photographic paper tends to crack easily due to long-term exposure to light and heat during long-term exhibitions, etc., leading to a decrease in product value. . (C) Object of the invention Therefore, the object of the invention is first of all to improve the surface gloss of the white background of photographic paper (hereinafter referred to as surface white gloss).
The goal is to provide a way to increase the The second object is to provide a method for increasing the surface black gloss of the black image area of photographic paper. Another object of the present invention is to provide photographic paper with increased surface gloss and high reflection density. (D) Structure of the Invention The object of the present invention is to contain a high-boiling point organic solvent in the photosensitive emulsion layer of photographic paper, and to apply it to the surface protective layer inner than the outermost layer of two or more surface protective layers. This was achieved by containing colloidal silica and further providing a high-boiling organic solvent and a layer not containing colloidal silica as the outermost layer of the surface protective layer. That is, in a photographic paper having at least one photosensitive emulsion layer on a support, at least one of the photosensitive emulsion layers is coated with a hydrophilic colloid binder (mainly consisting of gelatin) constituting the emulsion layer. ~150% by weight, preferably 10 to 100% by weight of a high boiling point organic solvent is contained, and among at least two or more surface protective layers, the surface protective layer that is inner than the outermost surface layer is made to contain a hydrophilic solvent constituting that layer. A colloidal colloid (mainly consisting of gelatin) contains colloidal silica in an amount of 5 to 120% by weight, preferably 10 to 80% by weight of the binder, and furthermore, the outermost layer of the surface protective layer contains colloidal silica and a high-boiling organic material. This was achieved by providing a solvent-free surface layer. In the present invention, the surface protective layer has a structure of two or more layers, and colloidal silica is used in one of the layers. As a patent in which the surface protective layer has a two-layer structure in this way, in JP-A-58-147734, the inner protective layer contains fine powder and the outermost protective layer contains oil droplets. The method is disclosed. This structure is related to a method for preventing abrasion-induced fogging (desensitization) caused by contact between photographic materials and packaging machines, cameras, processing machines, etc., and although it is effective as a countermeasure against external stress, photographic paper In terms of gloss, the configuration of this patent has a rather negative effect on the gloss. The high boiling point organic solvent used in the photosensitive emulsion layer of the present invention is preferably one having a boiling point of 150° C. or higher at normal pressure.
Organic solvents of this type can be chosen from carboxylic esters, phosphoric esters, carboxylic amides, ethers, substituted hydrocarbons. Specific examples include di-n-butyl phthalate, di-isooctylphthalate, dimethoxyethyl phthalate, di-n-butyl adipate, diisooctyl azelenate, Tri-n-butyl citrate, tricresyl phosphate,
Tri-n-butyl phosphoric acid ester, triisooctyl phosphoric acid ester, N/N-diethyl cabrylic acid amide, N/N-dimethylbalmitic acid amide, n
-butyl-m-puntadecyl phenyl ether,
Examples include ethyl-2,4-tert-butyl phenyl ether and chlorinated paraffin. The high boiling point organic solvent used in the present invention is contained in the silver halide photographic emulsion layer in an amount of 5 to 150% by weight based on the hydrophilic binder (mainly gelatin), preferably 10% by weight.
It is contained in a proportion of ~100% by weight. If the amount added is less than this, the expected effect will not be obtained, and on the other hand, if the amount added is more than the above range, it will be unfavorable in terms of film properties such as poor hardness. When introducing the high boiling point organic solvent used in the present invention into the photosensitive emulsion layer, it is dissolved in a low boiling point solvent such as methyl acetate, ethyl acetate, butyl propionate, cyclohexanol, etc. Anionic surfactants and nonionic surfactants such as sorbitan sesquioleate and sorbitan monolaurate are mixed with an aqueous solution containing a hydrophilic colloid material such as gelatin, and then mixed with a colloid mill, homogenizer, or ultrasonic dispersion device. A dispersion liquid obtained by emulsifying and dispersing the silver halide emulsion may be added to a silver halide photographic emulsion and applied as a coating liquid. Furthermore, additives such as antifoggants, developing agents, and other photographically useful chemicals can be included in the high-boiling organic solvent. Next, regarding the colloidal silica used in the innermost surface protective layer of the at least two surface protective layers of the present invention, ultrafine particles of silicic anhydride (silica) (particle size 50
mμ or less) dispersed in water, and furthermore, inorganic salts such as sodium hydroxide, lithium hydroxide, ammonium hydroxide, and organic salts such as tetramethylene ammonium ion are added to colloidal silica as an alkali component. It also includes those contained as stabilizers. In addition, as commercially available products,
Nissan Chemical Co., Ltd. Snowtex 20, Snowtex
30, Snowtex C, Snowtex N, Snowtex O, Snowtex S, manufactured by Dubon, Rudotsu AM, Rudotsu SM, Rudotsu HS, etc. are available. In the present invention, the colloidal silica is 5 to 120% by weight, preferably 10 to 80% by weight of the hydrophilic colloid (mainly composed of gelatin) binder constituting the surface protective layer inside the outermost layer.
Contain. Furthermore, in the present invention, the outermost surface protective layer includes:
By providing a layer that does not contain colloidal silica and high-boiling organic solvents as described above, this is a necessary element to prevent a decrease in the surface white gloss of the white background area and the surface black gloss of the black density area on the surface of the photographic paper. If the outermost surface protective layer contains colloidal silica, it not only causes a decrease in the white surface gloss of the white background of the stamp image, but also exposes the silica on the surface and causes it to be exposed to light and heat for a long time during long-term exhibitions, etc. However, there is a drawback that cracks tend to occur on the surface of the photographic paper. For this purpose, a layer not containing colloidal silica (non-photosensitive colloid layer) was provided in the outermost surface protective layer, thereby significantly improving surface gloss including surface white gloss. Furthermore, if the outermost surface protective layer contains a high boiling point organic solvent, both the surface gloss of the white background area and the surface black gloss of the black density area will decrease, resulting in an unattractive image.
As a photographic image, it has the disadvantage of lowering its commercial value. For this reason, it is necessary that the outermost surface protective layer does not contain any high boiling point organic solvent. In the present invention, firstly, the photosensitive emulsion layer contains a high boiling point organic solvent, secondly, the surface protective layer inside the outermost surface protective layer contains colloidal silica, and thirdly, the surface protective layer inside the outermost surface protective layer contains colloidal silica. By not including a high boiling point organic solvent and colloidal silica in the outermost surface protective layer, the surface gloss (surface white gloss in the white background area and surface black gloss in the black density area) is significantly improved, which led to the present invention. Even if one of these three elements is missing, no improvement in surface gloss can be expected, and some defects will occur. In particular, by providing these three elements, a high-boiling organic solvent in the photosensitive emulsion, colloidal silica in the inner surface protective layer, a high-boiling organic solvent in the outermost surface protective layer, and an outermost layer that does not contain colloidal silica. ,
The present invention was achieved by discovering a new fact that can significantly improve surface gloss (particularly surface black gloss in black density areas and surface gloss in white background areas) and black density that could not have been predicted. Regarding the film thickness structure of the surface protective layer (non-photosensitive hydrophilic colloid layer) composed of at least two layers in the present invention, the total film thickness is not particularly limited; The ratio of the thickness of the protective layer to the thickness of the outermost surface protective layer is not particularly limited. In the present invention, hydrophilic colloid substances used as binders in the surface protective layer (non-photosensitive hydrophilic colloid layer) consisting of at least two layers include gelatin, gelatin derivatives, enzyme-treated gelatin, and patent application Desalted gelatin such as 58-112451, hydrophilic synthetic polymers (e.g. vinyl polymers, styrene, maleic anhydride copolymers, styrene, condensates of maleic anhydride and polyvinyl alcohol, styrene-maleic acid copolymers) and acrylamide copolymers or blend compositions, acrylic acid copolymers, etc.), natural polymeric substances (e.g. colloidal albumin, casein, cellulose derivatives,
It may also contain a hydrophilic binder such as agar, sodium alginate, dextran, gum arabic, starch derivatives, etc., as well as a craft polymer of gelatin and acrylic acid disclosed in JP-A-11023-1983. In the present invention, the surface protective layer composed of at least two layers preferably contains an appropriate amount of a hardening agent and a surfactant. Specific examples of hardening agents include aldehyde compounds such as formaldehyde and glutaraldehyde, titone compounds such as diacetyl and micropendiol, and bis(2-chloroethylurea)-2-hydroxy-4,6-dichloro- 1,3,5 Triazine, U.S. Patent No.
Reactive halogen-containing compounds as described in US Pat. No. 3,635,718, divinyl sulfone, reactive olefin compounds as described in US Pat. No. 3,635,718, N-methylol compounds as described in US Pat. No. 2,732,316,
Isocyanates as described in US Pat. No. 3,103,437, aziridyl compounds as described in US Pat. No. 3,017,280 and US Pat. No. 2,983,611, carbodiside compounds as described in US Pat. Eboxy compounds, halogen carboxaldehydes such as mucochromic acid,
Examples include dioxane derivatives such as dihydroxydioxane, inorganic hardeners such as chromium alum, potassium alum, and zirconium sulfate, and these may be used alone or in combination of two or more. Specific examples of surfactants include natural surfactants such as saponin, nonionic surfactants such as alkylene oxide, glycerin, and glycidol, higher alkylamines, quaternary ammonium salts, pyridine, and other complexes. Cationic surfactants such as rings and sulfoniums, anionic surfactants containing acidic groups such as carboxylic acids, phosphoric acids, sulfuric acid ester groups, and phosphoric ester groups, amino acids, aminosulfonic acids, and sulfuric acid or phosphoric acid esters of amino alcohols. There are amphoteric surfactants such as, and these can be used alone or in combination of two or more. The silver halide emulsion used in the practice of the present invention can be prepared by known or commonly used methods. , silver chlorobromide, etc.), the size and crystal habit of silver halide grains, the ratio of silver halide to gelatin, and the pH of silver halide emulsions.
It is not limited by the type and amount of chemical sensitizers, PAg, chemical sensitizers, other additives, gelatin, and other binders. Examples of the support used in the silver halide photographic material of the present invention include paper laminated with baryta or polyolefin resin, a transparent film made opaque by adding a pigment such as titanium oxide, and a transparent film made opaque by adding a pigment such as titanium oxide. Examples include various films such as tate film, polystyrene film, polyethylene terephthalate film, and polycarbonate film. (E) Examples The present invention will be explained in detail below using Examples, but the present invention is not limited to these embodiments. Example 1 Silver chlorobromide emulsion (Br:
Cl = 60:40) was coated on a double-sided polyethylene laminated paper (glossy side) support with corona discharge processing using a slide hopper type extrusion coating machine to give 1.4 g/m ² of silver and 3.5 g/m ² of gelatin. Depending on the surface protection layer (one surface protection layer, gelatin 1.6g/m ² ) or two surface protection layers, i.e. gelatin 1.0g/m ² in the inner surface protection layer and gelatin 0.6g/m 2 in the outermost surface protection layer. It was applied simultaneously with m ² (two-layer coating or three-layer coating). Furthermore, a part of it is included in the photosensitive emulsion (and in the surface protective layer). High-boiling organic solvents are used in light-sensitive emulsions as dispersions as shown below. Dispersion: 20g of dioctyl phthalate and 8g of ethyl acetate.
Sodium triisopropylnaphthalene sulfonate 1 mixed and dissolved at 65℃ and heated to 50℃
was added to 100 c.c. of a 6% galatin aqueous solution containing 100 g of the product while stirring, and then dispersed with a homogenizer to prepare a dispersion. Table 1 shows the compositions of the surface protective layer (one layer or two layers: outermost layer and inner surface protective layer) and emulsion layer. The solid content of colloidal silica in the table is g/m ²
It was expressed as Furthermore, the surface glossiness (and maximum reflection density) of the white background part and black density part of each sample A to H was
Shown in the table. Among these values, the gloss value of the white background area was determined by normal photographic processing of each sample in a state of end dew, and the value of the surface gloss of the black area was determined by exposing each sample to moderate light. The maximum reflection density is the value measured after normal sensitometry and photographic processing, and after being left to dry naturally. The surface gloss value here was measured using a VG-ID type gloss meter (gloss meter) manufactured by Nippon Denshoku Kogyo Co., Ltd. at an incident angle of 60° and a light receiving angle of 60°. At the same time, these maximum reflection densities are
As shown in the table, where the measured value of reflection density is
This is based on the method described in TISK7611.

【table】

[Table] Compared to C, A, or B, when colloidal silica is included in the surface protective layer formed of a single layer, the surface gloss of the black density area increases only slightly, and the surface white gloss of the white background area increases only slightly. It can be seen that there is a significant decrease in Comparing E and C, it can be seen that the surface white gloss is improved by providing the outermost surface protective layer on the surface protective layer containing colloidal silica. When comparing D with A or B, the surface gloss increases only slightly by including a high boiling point organic solvent in the emulsion. On the other hand, in sample F, that is, the sample of the present invention, not only the surface black gloss of the black density area is significantly improved, but also the surface white gloss of the white background area is improved, which is more than can be imagined with C, D, and E. It is clear that the effect of improving the surface gloss can be obtained. Furthermore, it can be seen that sample F is the most effective because higher values of reflection density as well as surface gloss can be obtained than in any of A, B, C, D, and E. Compared to G and F, when colloidal silica is used in the outermost layer, the white gloss of the white background area is significantly reduced, which is not preferable. Furthermore, when compared with H and F, it is clear that if the outermost layer contains a high boiling point organic solvent, not only the white gloss but also the black gloss decreases, and no improvement effect on surface gloss can be obtained. Example 2 Using the same silver halide emulsion and the same gelatin as A to H of Example-1, the amount of gelatin adhered to the surface protective layer was 0.7 g/m ² to the inner surface protective layer.
Samples I, J, K, L, M, N, O, having a surface protective layer of 0.3 g/m ² as the outermost surface protective layer (1.0 g/m ² for the surface protective layer formed of one layer), I made P. (However, the high boiling point organic solvent in the outermost protective layer of sample P is 0.4 g/ ^m2 ) Regarding samples I to P,
The compositions of the two (or one) surface protective layer and photosensitive emulsion layer are shown in Table 3. Furthermore, the surface gloss and reflection density of the white background part and black density part of these samples were
Shown in the table. However, the measurement method is the same as in Example-1.

【table】

[Table] In this case, as in Example 1, the method of the present invention (sample N) has a clear effect of improving the black gloss in the unexpectedly significant black density area and the effectiveness of white gloss. It can be seen that even when the surface protective layer is made thinner than in Example 1, it is most effective for obtaining high reflection density and surface gloss (white surface gloss in the white background area and black surface gloss in the black density area). Furthermore, the method of the present invention (sample N), which contains a high boiling point organic solvent in the photosensitive emulsion layer, is preferable to any of I, J, K, L, M, and O, P. It is clear that the surface gloss of the photographic paper is significantly improved by providing colloidal silica in the surface protective layer and a layer containing no colloidal silica or high-boiling organic solvent as the outermost layer.

Claims (1)

[Claims] 1 In a photographic material having at least one light-sensitive emulsion layer and at least two surface protective layers on a support, the binder is
~150% by weight of a high-boiling organic solvent is contained, and the surface protective layer inside the outermost layer of the surface protective layer contains 5~120% by weight of colloidal silica of the binder, and further, the outermost layer of the surface protective layer is is a black and white photographic paper characterized by not containing high boiling point organic solvents and colloidal silica.