JPH0462064B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a photographic coating solution containing gelatin, and more particularly to a photographic coating solution that is economical, has constant coating properties, and is suitable for high-speed thin layer coating that provides good film properties and surface gloss characteristics. be. In the production of photographic materials, gelatin is commonly used as a protective colloid component for silver halide and other additives. Gelatin is a unique natural polymer substance whose aqueous solution can undergo a sensitive sol-gel transformation due to temperature changes, and because of this characteristic, gelatin still replaces other synthetic polymer compounds in the photographic industry. I can't do it. In addition to the above-mentioned usefulness, gelatin is also useful because it can be easily crosslinked with a hardening agent, it has high water solubility and can be easily concentrated, and it has good orientation and has good surface gloss when made into a photographic film. It has the following characteristics: it is photographically inert or active, it is easy to handle and non-polluting, and it has excellent transparency and no coloring, which are all things that are lacking in today's photographic materials. It has become an impossible component. Photographic coating solutions containing gelatin are usually coated onto film by methods such as dipping, scraping coating using an air knife, extrusion coating using extrusion, bead coating using a slide hopper, and curtain coating using a free-fall method. It is coated onto a flexible support such as paper or a non-flexible support such as glass. The application must be as smooth as possible, without streaks or unevenness, and in addition, there should be no defects (spot-like uncoated areas) called repellency.
It is necessary to be able to do so. Furthermore, it is necessary that the surface of the coating film has excellent gloss and that the surface does not become cloudy or matte. These requirements are important factors that determine the quality of factory production, and therefore consideration is given to ensure that the physicochemical properties of the coating solution meet these requirements. In addition to quality, what is important is productivity, and the establishment of coating liquid conditions that can be used on a commercial basis. One countermeasure for this purpose is to increase the speed of coating and to apply thinner layers. If the water content of the coating solution is reduced and thin layer coating is performed, the negative cost of drying will be reduced, speeding up will be possible, and economical efficiency will increase. Another countermeasure is to reduce variable costs such as raw materials. In addition to essential additives to maintain photographic performance, materials necessary to make coating advantageous are often added.
For example, a surfactant as a coating aid, a thickening agent to provide the necessary viscosity, etc. are appropriately and effectively used. Reducing these materials to the bare minimum reduces costs, productivity, and improves commercial profits. One of the conditions for stably coating a gelatin-containing photographic coating solution at high speed is the viscosity of the coating solution. Even if it contains the minimum amount of gelatin required to maintain photographic performance, coating failures (such as the aforementioned streaks, unevenness, and repellency) may occur if the coating film thickness is below the limit necessary for smooth coating. Therefore, the lower limit of the coating film thickness is limited, and it often happens that the gelatin concentration is insufficient and the required viscosity cannot be obtained. In recent years, the amount of gelatin used in photographs has been increasingly reduced in order to provide compatibility with rapid processing, reduce costs, and improve image sharpness by reducing the film thickness (dry film thickness) of photographic material layers. The viscosity of coating liquids is also decreasing. One strategy to increase viscosity without concentrating is to
The solution is to use gelatin with a high molecular weight, so-called high viscosity gelatin. However, such gelatin has a low thickening rate and is not only insufficient for the purpose of thickening, but also has problems such as high manufacturing cost and the tendency to form poorly soluble gelatin lumps. A much more advantageous way to increase the viscosity is to add thickening agents, the addition of small amounts of which allows large thickening rates to be obtained. Particularly useful thickening agents for this purpose are e.g.
As described in the above publication, it is a sulfuric acid esterified polymer compound, such as a partially sulfuric ester of polyvinyl alcohol or a sulfuric ester of polysaccharide. The necessary and sufficient thickening effect can be obtained by adding these thickening agents to gelatin in amounts of several percent or less, and an unlimited number of effects can be expected depending on the amount added. However, when manufacturing photographic coating liquids, it is usually done by adding a certain amount of thickening agent based on a certain prescription to each manufacturing lot; However, it is often a problem that the viscosity changes when the production lot of gelatin used changes. To remedy this, it is necessary to adjust the coating solution by adding a smaller amount of thickening agent than the prescribed amount, measure the viscosity, and repeat the addition of the thickening agent until the desired viscosity is reached. do. Such work is not only extremely inefficient in routine work, but also causes other problems as described below. That is, when the amount of the thickening agent added changes, the orientation of gelatin changes. As the amount added increases, the sol-to-gel specific optical rotation of the coating solution decreases, and the specific optical rotation of the coating film also decreases.
For this reason, even if the viscosity and set point are the same, the surface smoothness of the coating film actually obtained deteriorates, which causes deterioration in gloss.
Additionally, organic or inorganic hardeners are usually used to harden gelatin films, but as the amount of thickening agent increases, the crosslinking reactivity of the hardener decreases, making it difficult to harden the film. . The present inventors investigated and researched the causes of large changes in viscosity depending on the production lot of gelatin, and found that the main cause was the concentration of trace amounts of calcium ions (Ca ⁺⁺ ) contained in gelatin. I discovered something. That is, calcium ions inevitably remain in gelatin produced by a lime treatment method or an acid treatment method, and the concentration thereof always exists with some variation. The presence of this calcium ion inhibits the thickening caused by the reaction between gelatin and the thickening agent compound, and therefore, the variation in the calcium ion content in gelatin is reduced when a certain amount of thickening agent is added to gelatin. This causes large variations in viscosity. From this, if the calcium ion concentration in gelatin is kept constant, the above-mentioned problem will not occur, but the lower the calcium ion content, the more
Since only a small amount of thickening agent is needed, the production costs are not only reduced, but also the hardness and surface properties (gloss) of the coating after being applied to the support are improved. An object of the present invention is to provide a gelatin-containing photographic coating solution suitable for coating on a support such as a film, which achieves maximum thickening effects such as thickening with a minimum amount of thickening agent. To provide a gelatin-containing photographic coating liquid which can increase the hardness and always maintain good hardness and surface gloss of the coated film. This purpose is to improve the calcium ion (Ca ⁺⁺ ) content of gelatin, which is used as a protective colloid, in a gelatin-containing photographic coating solution that is to form a photographic layer, and in which the coating solution contains a thickening agent and is used as a protective colloid. This is achieved by a gelatin-containing photographic coating solution characterized in that the amount is 2000 ppm or less based on dry gelatin. According to a preferred embodiment of the present invention, in a coating solution for a photographic light-sensitive material containing gelatin to form a photographic layer, the content of calcium ions (Ca ⁺⁺ ) in gelatin used as a protective colloid is equal to that of dry gelatin. 2000 ppm or less, and the general formula []P(-A)n (wherein P represents the main chain including the main chain or side chain of a natural or synthetic polymer, and in many cases, the carbon-carbon Although it is a chain consisting of bonds, it may contain atoms other than carbon, such as oxygen, nitrogen, etc., and may also have a hydroxyl group.Also, A is an acid such as -OSO ₃ M, -SO ₃ M, -COOM, etc. Indicates the group,
M represents hydrogen, alkali metal or _-NH4 , n
is an integer greater than or equal to 1. ) or general formula [] (In the formula, B represents an optionally substituted vinyl group, and m is an integer.) be. Gelatin, which is generally used for photography, is manufactured by solubilizing collagen, the main component of animal skin and bones, in hot water, but it is difficult to extract the raw material immediately in hot water. In an industrial production method, collagen is partially hydrolyzed in advance by pretreatment of immersing raw materials in milk of lime for 1 to 3 months, that is, a long-term pretreatment called liming. Bovine bone ossein gelatin, which is commonly used, is also produced by the above method and commercialized containing some calcium ions. In the gelatin used in the present invention, the content of calcium ions is higher than that of dry gelatin.
Although any method can be used to reduce the amount to 2000 ppm or less, it can be easily achieved, for example, by passing it through a cation exchange resin column. In addition, recently, gelatin made from pig skin has been attracting attention, but it does not require lime treatment like bone ossein, but instead requires so-called acid treatment, which involves soaking it in an acid such as sulfuric acid for several days and then extracting it. Gelatin also falls within the scope of the present invention and is considered useful as low calcium gelatin. A typical example of the compound represented by the general formula [] used in the present invention is a polymeric sulfate ester compound, which is a synthetic or natural compound having a hydroxyl group such as polyvinyl alcohol, cellulose, alginic acid, starch, etc. It can be easily obtained by using a polymer material as a raw material and treating it with sulfuric acid, chlorosulfonic acid, etc. to convert it into a sulfuric acid ester. Specific examples include Japanese Patent Publication No. 36-21574, US Patent No. 3383307, US Patent No. 3516983, US Patent No. 3391061,
Although described in the specifications of the same No. 3000790, the same No. 3624069, and the same No. 3653906, as a particularly useful example, the exemplified compound [A] [However, l = 5 to 1000] Exemplary compound [B] [However, m=5 to 1000]. Also, as a commercially available product, for example, there is KELCO SCS supplied by Kelco Corporation of New Jersey, USA. In the compound represented by the general formula [] used in the present invention, B is styrene,
α-methylstyrene, vinyl acetate, acrylic acid,
Mention may be made of methacrylic acid, acrylic acid methyl ester, ethyl vinyl ether and isopropyl vinyl ether. When B is a vinyl methyl group, the product name is GANTREZ AN, as a vinyl methyl ether-maleic anhydride copolymer.
There is General Aniline & Film Corp. The thickening agent represented by the general formula [] or [] used in the present invention can be dissolved in water of any hydrogen ion concentration and can also be dissolved in an organic solvent. Aqueous solutions and organic solvent solutions are viscous, and the solutions are stable regardless of whether acid or alkali is added.
It is effective as a stabilizer and protective glue and exhibits adhesive properties to substrate surfaces. When the thickening agent of the general formula [] is dissolved in water or alcohol, it assumes the following ring-opened maleic acid ester molecular structure and thickens. Compounds that are completely compatible with such thickening agents at a ratio of 1/3 to 3/1 include casein, hydroxyethyl cellulose polyacrylamide, acrylamide copolymer, dextrin, polyvinyl alcohol, polyvinylpyrrolidone, and vinylpyrrolidone-acetic acid. Examples include vinyl copolymers and starch. The thickening agent used in the present invention is not limited to the compound represented by the above general formula [] or [], and any known thickening agent compound may be used. You may use more than one species in combination. When the emulsion used in the gelatin-containing photographic coating solution of the present invention is a silver halide emulsion, examples of the silver halide include silver chloride, silver bromide, silver chlorobromide, silver chloroiodobromide, and silver iodobromide. It can be any type of silver, depending on the crystal form and crystal habit of the silver halide, the silver ion concentration in the emulsion, and the practical pH (range of 5 to 7).
The present invention can be applied without depending on the above. The silver halide emulsion may contain one type or a combination of two or more of various metal ions (for example, rhodium, iridium, lead, thallium ions, etc.).・Science (The Journal of
It may also contain crystal habit modifiers, known fog suppressants, stabilizers, etc., such as those described in Photographic Science) Vol. 13 (1965). In addition, the silver halide emulsion can be subjected to known chemical sensitization (for example, sulfur sensitization, noble metal sensitization, reduction sensitization, etc.), and optical sensitization (for example, tokukosho sensitization) depending on the required sensitizing wavelength range. No. 43-4930, No. 48-
No. 42974, JP-A-49-106322, JP-A No. 49-111629,
No. 48-56426, Special Publication No. 46-549, No. 50-40662
No. 47-26126, 48-28224, 48-
No. 24726, No. 48-33817, No. 48-41733, No. 48
−59828, U.S. Patent No. 2177402, U.S. Patent No. 3752670
No. 45-19034, 50-37538, JP
46-1630 etc.) may be applied. Furthermore, ultraviolet absorbers (e.g. German patent no.
No. 1182066, JP-A-47-1026, JP-A No. 50-87326,
U.S. Patent No. 3253921, U.S. Patent No. 2739888, U.S. Patent No.
3250617), color antifoggants (e.g., U.S. Pat. No. 2,728,659;
2991177, British Patent No. 891158, British Patent No. 861138,
Compounds described in JP-A-51-27333), desilvering accelerators (e.g., compounds described in JP-A-48-53725), sharpness-enhancing dyes (e.g., Amaranth, JP-A-47-1999)
17421 (compound described in No. 17421), etc.
Mainly, silver halide emulsions contain various couplers (for example, U.S. Pat. No. 2,376,679, U.S. Pat. No. 2,991,177,
No. 3021215, JP-A-48-30933, JP-A No. 48-
No. 43938, No. 48-66836, No. 49-42345, No. 51
-9449, No. 50-132926, No. 50-158329, Japanese Patent Publication No. 49-13576, Japanese Patent Publication No. 51-10783, etc.). As other additives, hardening agents and surfactants are used as appropriate. For example, inorganic and organic hardeners such as aldehydes, ketones, carboxylic acids, active halides, epoxies, aziridines, active olefins, isocyanates, carbondiimides, vinyl sulfones, chrome alums, potassium alums, etc. may be used alone or in combination. It is preferable to include it. It is also preferable to contain a surfactant commonly known in the photographic industry, such as saponin, sodium alkylbenzene sulfonate, sulfosuccinic acid ester salt, and the fluorine-based surfactant described in Japanese Patent Publication No. 47-9303. As the gelatin in the gelatin-containing photographic coating solution according to the present invention, various gelatins such as lime-treated gelatin, acid-treated gelatin, gelatin derivatives (eg, acylated gelatin, etc.) can be used alone or in combination, and natural or synthetic polymers can also be used. can be included. As the support to which the gelatin-containing photographic coating solution of the present invention is applied, conventionally known photographic supports can be used, such as various films such as cellulose acetate, polystyrene, polyethylene terephthalate, and polycarbonate, and baryta. A flexible support such as paper or polyolefin resin laminated paper, or a non-flexible support such as glass is used. The gelatin-containing photographic coating solution of the present invention can be applied to commercially available silver halide photographic materials such as color negative film, color photographic paper, monochrome film,
In addition to monochrome photographic paper, it can be applied as a constituent layer of any photographic material containing gelatin, such as industrial printing sensitive materials, X-ray films, and even special light-sensitive materials that apply diffusion transfer and dye bleaching.For example, silver halide emulsions It is useful for layers, silver halide emulsion layers containing couplers, backing layers, antihalation layers, subbing layers, interlayers, ultraviolet absorbing filter layers, protective layers, etc. According to the embodiments of the present invention, it is possible not only to obtain a coating liquid with a stable high viscosity by adding a minimum amount of thickening agent, but also to coat a homogeneous thin film at high speed, and to improve the coating film. It exhibits the excellent effect of maintaining good hardening properties and surface gloss. Examples of the gelatin-containing photographic coating solution of the present invention are shown below, but the present invention is not limited to these Examples. Example 1 Lime-treated gelatin produced by a conventional method was subjected to ion exchange treatment to change the Ca ⁺⁺ content 4
A 5% aqueous solution of seed gelatin (1) to (4) was mixed with the above-mentioned exemplified compound [A] (provided that l≒40) as a thickening agent so that the viscosity at 35°C was equal to 25 c.p. The amount was adjusted and added. The sol → gel specific optical rotation of this liquid was measured using a Nikko Bunko DP-4 type polarimeter.
Measurements were made using a 10 mm quartz cell at 589 nm line. Also, this liquid contains a hardening agent. 2%/dried gelatin was applied to a photographic support laminated with polyethylene on both sides to a thickness of 60μ, dried under certain conditions, and the optical rotation of the film was measured using the same polarimeter as above. Furthermore, the swelling rate after immersing the same sample in a color paper developer for 3 minutes at 33°C [(swollen film weight) - (dry film weight)/dry film weight] x 100%, and the surface gloss after drying in normal processing. The results of a visual evaluation (according to a three-level system of ○=good, ×=poor, and △=slightly good) were determined. Table 1 shows the Ca ⁺⁺ content of each gelatin, the amount of thickening agent required, the sol-to-gel specific optical rotation at 25°C, the optical rotation of the film after coating, the swelling rate of the film at 25°C, and the surface area of the film. The results of visual evaluation of glossiness are shown.

[Table] As is clear from the results in Table 1, sample (1) in which the content of Ca ⁺⁺ in the gelatin used is within the range of the present invention.
and (2), it can be seen that by adding a small amount of thickening agent, the orientation of gelatin molecules is excellent and the physical properties such as film hardness and surface gloss are good. FIG. 3 shows the relationship between the optical rotation -[α] _d of the coated film and the content of the thickening agent. A 5% gelatin solution to which the exemplified compound [A] of the thickening agent used in the above example was added by varying it from 0 to 1 g/l was applied onto a film support to a thickness of 40μ to form a film, Freezing point range (set zone) of 2-3℃
The sample was gelatinized at 25°C for 2 minutes and then dried with warm air at 40°C for 2 minutes. The Ca ⁺⁺ content varies depending on the type of gelatin, but regardless of the Ca ⁺⁺ content, as the thickening agent content increases, the optical rotation -
It can be seen that [α] _d decreases and the surface gloss deteriorates. Therefore, in the case of Gel-A shown in Figure 3, which requires a small amount of thickening agent, the orientation of gelatin molecules is not impaired by the thickening agent, so a film is used. It can be seen that it is possible to maintain a high optical rotation and high surface gloss. Example 2 ^Six kinds of gelatin No. Adjust 5) to (10) and add thickening agent [C] [However, n≈50] The viscosity at 35° C. when added was measured by varying the amount. The results are shown in FIG.

[Table] Figure 2 shows the relationship between the amount of thickening agent [C] that gives a constant viscosity of 25 cp at 35°C and the Ca ⁺⁺ concentration. From Figures 1 and 2, the viscosity that changes with the addition of the thickening agent [C] depends on the Ca ⁺⁺ concentration in gelatin, and the lower the Ca ⁺⁺ concentration, below 2000 ppm, the greater the viscosity increasing effect. It can be seen that thickening is inhibited when the amount exceeds 2000 ppm. Example 3 Three types of gelatin No. 3 were prepared by changing the Ca ⁺⁺ content by ion exchange treatment of a 5% lime-treated gelatin aqueous solution (the gelatin used was Takarazuka Gelatin TM-3000).
= Adjust ~(13) and add thickening agent [D] (Product name: GANTREZ AN 139 General Aniline & Film Corp.) was added to a certain amount and the viscosity at 35°C was measured. The results are shown in Table 3.

[Table] As is clear from Table 3, the viscosity of gelatin changes with the addition of thickening agent [D].
Depends on Ca ⁺⁺ concentration, especially when Ca ⁺⁺ concentration
The lower it is below 2000ppm, the more effective it is to thicken.
It is recognized that the thickening effect is small when the amount exceeds 2000 ppm. Example 4 Four types of gelatin were prepared by changing the Ca ⁺⁺ content by ion exchange treatment of a 5% lime-treated gelatin aqueous solution (the gelatin used was Takarazuka Gelatin TM-3000), and the above-mentioned thickening agent [B ] and thickening agent [D] and six kinds of samples [No.(1
4) to (19) were prepared and their viscosities at 35°C were measured. The results are shown in Table 4.

[Table] From Table 4, it can be seen that the combined use of thickening agent [B] and thickening agent [D] results in a slight increase in viscosity compared to the use of either one alone, and in this case as well, the Ca ⁺⁺ concentration It is recognized that the thickening effect is small when it exceeds 2000 ppm.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between Ca ⁺⁺ concentration and viscosity in the gelatin-containing photographic coating solution of the present invention. FIG. 2 is a graph showing the relationship between the amount of the thickening agent [A] added and the Ca ⁺⁺ concentration that provides a constant viscosity (35° C., 25 cp) in the gelatin-containing photographic coating solution of the present invention. FIG. 3 is a graph showing the relationship between the film optical rotation and the content of the thickening agent [A] in the gelatin-containing photographic coating solution of the present invention.

Claims (1)

[Claims] 1. In a gelatin-containing photographic coating solution for forming a photographic layer, the coating solution contains a thickening agent, and the calcium ion (Ca ⁺⁺ ) content of the gelatin used as a protective colloid is lower than that of dry gelatin. A photographic coating liquid containing gelatin, characterized by a gelatin content of 2000 ppm or less.