JPH05273698A - Photographic base - Google Patents

Abstract

PURPOSE:To obtain the photographic base which does not generate the degradation in the gloss by the recesses generated on the surface of the photographic emulsion layer of the photographic paper having the surface quality of a smooth surface. CONSTITUTION:This photographic base is formed by coating both surfaces of paper essentially consisting of natural pulp and/or synthetic pulp with a polyolefin resin. The value of Ra, defined by JIS(Japanese Industrial Standards) B 0601-1982, of the front surface shape of the image forming surface of such photographic base is <=0.20mum. The value of Rz defined by JIS B 0601-1982, of the shape of surface opposite from the image forming surface, i.e., rear surface is >=3.50mu and <=5.50mum and the value of Ra is >=0.30mum, more preferably <=0.55mum. As a result, the photographic which does not generate the degradation in the gloss by the recesses generated on the front surface of the photographic emulsion layer of the photographic paper having the smooth surface is obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographic support whose base is paper having natural pulp as its main component and whose both surfaces are coated with a polyolefin resin. More specifically, the present invention relates to a polyolefin resin-coated photographic support, which is characterized in that the lowering of the gloss of the image forming surface due to the transfer of the back surface shape to the image forming surface of photographic printing paper is prevented.

[0002]

2. Description of the Related Art Conventionally, as a photographic support (hereinafter abbreviated as "support"), so-called bariter paper has been used in which a baryta layer mainly composed of barium sulfate is coated on one side of paper, but recently it has been developed. In order to automate and speed up the processing, waterproof photographic printing paper in which both sides of the base paper are coated with hydrophobic polyolefin resin has come to be used, and at present, it occupies most of the support.

The production of photographic printing paper (hereinafter abbreviated as photographic paper) is carried out by coating a photographic emulsion on a support by various coating methods and passing it through a drying zone to form a photographic emulsion layer (hereinafter referred to as emulsion). A method in which a layer (abbreviated as a layer) is adjusted to a predetermined water content and then wound is generally used. Gelatin is generally used as a binder for this emulsion layer which finally becomes an image forming layer. In addition, the binder used in the emulsion layer is required to have sufficient film strength in processing steps such as development, stopping, fixing, and washing (hereinafter abbreviated as development processing step). It is generally hardened by.
The emulsion layer immediately after being coated on a support, dried and conditioned, and wound into a roll does not have sufficient film strength because the crosslinking reaction of the binder by the hardener has not progressed. .. Usually, the back surface shape of the support is a rough surface shape from the viewpoint of front and back discrimination, operability, etc.In this case, the back surface shape is transferred to the surface of the wound emulsion layer,
This will cause minute depressions. The fine dents generated on the surface of the emulsion layer are fixed by the progress of the hardening of the emulsion layer and do not recover even if the binder swells during the subsequent development processing step. When the surface is smooth as shown in the above, the surface gloss is finally lowered.

In order to solve this, as a result of studying winding up the photographic printing paper after coating, drying and humidity adjustment with a low tension, as a result, the recesses on the surface of the emulsion layer are reduced, and the gloss is lowered after the development processing step. Has also disappeared. However, if the winding tension is lowered to the point where the dent is eliminated, so-called winding deviation occurs in the winding process of the printing paper and the finishing process such as slitting, and the productivity is remarkably reduced. In addition, as another measure, we examined the commercialization of photographic paper after winding by slitting it before the hardening of the emulsion layer. As a result, the decrease in gloss due to the depression of the emulsion layer is solved, but the production process is restricted, and the productivity is decreased.When the product is in the form of a roll, the tension during winding is as described above. Since it must be set low and rewinding must be performed to prevent winding deviation after the dura mater progresses, the productivity is also significantly reduced. For this reason, it is necessary to take measures against the decrease in gloss due to the dents generated on the surface of the emulsion layer with a support.

As a method of coping with this decrease in gloss with a support, as shown in JP-A-60-6944, the Ra value of the back surface shape is 0.3 μm or more and 2.5 μm or less.
There is the following method. This method is effective for reducing gloss which occurs in stripes in the flow direction when the emulsion layer is relatively thick among color printing paper and monochrome printing paper. However, in order to improve the drying property of photographic paper, it is necessary to reduce the liquid absorption amount of the emulsion layer in the development processing step, and recent photographic paper, especially monochrome photographic paper, has a tendency to thin the emulsion layer. Therefore, it is not possible to completely eliminate the deterioration in gloss as a result. For the same reason, as disclosed in Japanese Patent Laid-Open No. 2-226142,
Even if a support having a back surface shape Ra of 1.1 μm or more and 2.2 μm or less is used, it is not possible to completely eliminate the decrease in gloss.

[0006]

SUMMARY OF THE INVENTION The present invention is directed to a photographic paper having a smooth surface quality, which is caused by the depressions formed on the surface of the emulsion layer.
An object is to provide a photographic support that does not cause a decrease in gloss.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a photographic support in which both sides of a paper containing natural pulp and / or synthetic pulp as a main component are coated with a polyolefin resin, and the surface shape of the image forming surface. Of JIS B0601-1
In the photographic support having a Ra value defined by 982 of 0.20 μm or less, the Rz value defined by JIS B0601-1982 of the surface opposite to the image forming surface, that is, the back surface, is 3 It is achieved by a photographic support having a value of 0.50 μm or more and 5.50 μm or less and an Ra value defined by JIS B0601-1982 of 0.30 μm or more. Another object of the present invention is to provide a backside shape JI.
The value of Ra defined in SB0601-1982 is 0.
Further effects can be expected with a photographic support having a thickness of 55 μm or less.

The details of the present invention will be described below. The dry thickness of the emulsion layer varies depending on the type of printing paper, but is generally 7 to 8 μm for color printing paper and 4 to 5 μm for monochrome printing paper. As described above, coating on the support,
Since the emulsion layer immediately after being dried and humidity-controlled does not have sufficient film strength, the shape of the back surface of the support is transferred after being wound, and fine recesses are formed on the surface of the emulsion layer. As a result of analyzing the depressions on the surface of the emulsion layer, the depth of the depressions was found to be proportional to the 10-point average roughness (Rz) on the back surface of the support, and the average depth was 70 to 80% of Rz. .. The gloss of the surface of the emulsion layer is not a practical problem when Ra of the surface of the support on which the emulsion layer is coated is larger than 0.20 μm, that is, a rough surface. In this case, the gloss will be lowered, and the commercial value of the final printing paper will be lowered. The dents on the emulsion layer surface that occurred during the photographic paper manufacturing process become smaller due to the swelling of the binder in the subsequent development processing step, but if the dents are large, they cannot be completely restored. As a result, the gloss of the emulsion layer surface is reduced. The size of the recess restored after the development process varies depending on the hardness of the emulsion layer, but is almost completely restored when the depth is 70% or less of the thickness of the emulsion layer. That is, in order to prevent the gloss of a monochrome photographic paper having a small emulsion layer thickness from decreasing, Rz of the back surface of the support is set to 5.50 μm.
It must be m or less. However, when Rz on the back surface of the support is less than 3.50 μm, the adhesion between the back surface of the support and the emulsion layer is high, and the back surface of the support and the entire surface of the emulsion layer are in close contact with each other. Picking occurs, and as a result, the gloss of the emulsion layer surface decreases. Ra of the back surface of the support at this time is 0.30.
If it is less than μm, as described in Japanese Examined Patent Publication No. 60-6944, there is a problem in operation. However, when the Ra value is larger than 0.55 μm, although there is no problem in practical use, a slight decrease in gloss is observed, and therefore it is preferable that the Ra value be less than this value.

Natural pulp is mainly used as the pulp used in the practice of the present invention. However, synthetic pulp or synthetic fiber other than natural pulp may be used if necessary, or a mixture thereof may be used. Is also good. Natural pulp is usually bleached by chlorine, hypochlorite, chlorine dioxide bleaching, alkali extraction or alkali treatment, and if necessary, peroxide bleaching with hydrogen peroxide, peracetic acid, etc., and a combination thereof. Wood pulp of softwood pulp, hardwood pulp, mixed wood of hardwood mixed pulp that has been subjected to is advantageously used, also, kraft pulp, sulfite pulp, soda pulp, and the like, and various pulps such as pulp using an anthraquinone compound as a cooking aid. The thing can be used. The substrate (base paper) of the support used in the present invention includes a water-soluble synthetic resin, a sizing agent, and
In addition to pigments and dyes, various additives can be contained. For example, water-soluble polymer compounds such as anionized polyacrylamide and cationized starch, wet strength agents such as polyaminopolyamide epichlorohydrin resin, melamine resin, and urea resin, and fillers such as clay, kaolin, calcium carbonate, barium sulfate, and oxidation. Advantageously, titanium, etc., and sodium hydroxide, sodium carbonate, etc., as a pH adjusting agent, and a dye, a fluorescent whitening agent, etc., are appropriately combined and contained. Further, for the papermaking of the base paper, a commonly used paper machine such as a Fourdrinier paper machine or a round net paper machine can be used. It is advantageous that the base paper used in the present invention contains various water-soluble polymer compounds and additives by a spray or a tab size press. As such water-soluble polymer compounds, cationized starch, polyvinyl alcohol, carboxy-modified polyvinyl alcohol, carboxymethyl cellulose, hydroxyethyl cellulose, cellulose sulfate, gelatin, casein, sodium polyacrylate, styrene-maleic anhydride sodium salt, sodium polystyrene sulfonate As a sizing agent, petroleum resin emulsion, ammonium salt of styrene-maleic anhydride copolymer alkyl ester, etc., latex of styrene-butadiene copolymer, ethylene-vinyl acetate copolymer, polyethylene-vinylidene chloride copolymer, etc. , Emulsions, hygroscopic substances such as glycerin and polyethylene glycol, pigments such as clay, kaolin, talc, barium sulfate, titanium oxide Such as pH adjusting agents, hydrochloric acid, phosphoric acid, sulfuric acid, sodium hydroxide, various acids such as sodium carbonate, alkali, dyes, it is advantageous allowed to contain a combination of a fluorescent whitening agent. The thickness of the base paper is not particularly limited, but a material having good surface smoothness obtained by compressing the base paper by applying a pressure with a calender after paper making, for example, a base paper having an Ra value of 1.20 μm or less is preferable, The basis weight is preferably 140 to 250 g / m ² .

Examples of the film-forming resin used in the present invention include polyolefin, polystyrene, polyvinyl chloride, polyacrylic acid ester, linear polyester such as polyethylene phthalate, polycarbonate, polyamide such as nylon, cellulose ester and polyacrylonitrile. Homopolymers or copolymers such as ethylene-vinyl acetate copolymers and mixtures thereof may be any resin capable of coating a resin film on the base paper, and are not particularly limited, but polyolefin resins are extrusion coatable and base paper. It is particularly advantageous in terms of good adhesion with, cost, etc. The polyolefin resin referred to here is a copolymer of two or more olefins, such as a homopolymer of olefins such as low density polyethylene, high density polyethylene, polypropylene, polybutene, and polypentene, or a copolymer of two or more olefins. A mixture of various densities and melt viscosity indexes (melt index: MI) can be used alone or in combination, but low density polyethylene, high density polyethylene, or a mixture thereof is particularly preferable. .. Further, in the resin capable of forming a film, titanium oxide, zinc oxide, talc, white pigment such as calcium carbonate, stearic acid amide, fatty acid amide such as arachidic acid amide, zinc stearate, calcium stearate, aluminum stearate, Fatty acid metal salts such as magnesium stearate, zirconium octylate, sodium palmitate, calcium palmitate, sodium laurate, tetrakis [methylene-3 (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, Antioxidants such as 2,6-di-tert-butyl-4-methylphenol, blue pigments and dyes such as cobalt blue, ultramarine blue, cerulean blue and phthalocyanine blue, cobalt violet, fast violet, man Magenta pigments or dyes such as emissions purple, bis (tert- butyl benzoxazole) thiophene, bis fluorescent whitening agents, ultraviolet absorbents eg Ciba Geigy TINUVIN 320 (such as methyl benzoxazole) naphthalene, Tinuvin 3
26, various additives such as Tinuvin 328 can be added in an appropriate combination. As a method of adding these additives to a resin, preferably a polyolefin resin, a heating kneading roll, a Banbury mixer, a kneader,
The method of melt mixing with an extruder for kneading is the most suitable, and it is also possible to create and use a compound containing all the components in the desired composition ratio from the beginning, or use a master containing each component in a high concentration. A batch may be prepared for each component, and they may be mixed in a desired ratio and used.

The support in the present invention is manufactured by a so-called extrusion coating method in which a resin which is heated and melted is cast on a base paper which is normally running. Further, it is preferable that the surface of the raw paper is subjected to an activation treatment such as a corona discharge treatment or a frame treatment before the resin is coated on the raw paper. The thickness of the resin layer of the support in the present invention is not particularly limited, but in general, it is advantageous that the resin is extrusion coated to a thickness of about 5 to 60 μm, preferably 25 to 35 μm.
The cooling roll used for extrusion coating needs to be selected so that the target surface shape (values of Ra and Rz) can be obtained. The cooling roll is manufactured by a dry sandblast method, an etching method, an embossing method. Method, liquid honing method and the like can be used, and the manufacturing method is not limited. The support of the present invention may be provided with various silver halide emulsion layers. For example, silver chloride,
A silver bromide, silver chlorobromide, silver iodobromide, and silver chloroiodobromide emulsion layer can be provided. Further, the silver halide emulsion layer may contain a color coupler to provide a multilayer silver halide photographic constituent layer. Further, in addition to the silver halide emulsion layer, a protective layer, an intermediate layer and the like can be provided if necessary. As a binder for these silver halide emulsion layers, protective layers, intermediate layers, etc. (hereinafter referred to as emulsion layers), hydrophilic polymer compounds such as gelatin, polyvinylpyrrolidone, polyvinyl alcohol, sulfate ester compounds of polysaccharides, etc. are used. You can The silver halide emulsion layer may contain various additives. For example, as a spectral sensitizing dye, a cyanine dye,
Water-soluble gold compounds, sulfur compounds, etc. as chemical sensitizers such as merocyanine dyes, hydroxy-triazolopyrimidine compounds, mercapto-heterocyclic compounds, etc. as antifoggants or stabilizers, hardeners, formalin, vinyl, etc. Surfactants such as sulfone compounds and aziridine compounds, alkylbenzene sulfonates, sulfosuccinic acid ester salts, etc., antifouling agents, dialkylhydroquinone compounds, etc., fluorescent brightening agents, sharpness improving dyes, antistatic agents, pH adjustment A water-soluble iridium, a water-soluble rhodium compound and the like can be contained in an appropriate combination during the formation and dispersion of the agent and the silver halide.

[0012]

EXAMPLES The present invention will be described in detail below with reference to specific examples.

[Examples 1 to 6 and Comparative Examples 1 to 9] A 1: 1 mixture of hardwood kraft pulp (LBKP) and softwood bleached sulfite pulp (LBSP) was beaten to a Canadian standard freeness of 300 ml to produce pulp. A slurry was created. Alkyl ketene dimer as a sizing agent to 0.5% by weight of pulp, polyacrylamide as a strength agent to 1.0% by weight of pulp, cationized starch to 2.0% by weight of pulp and polyamide epichlorohydrin as a sizing agent. Add 0.5 wt% pulp and dilute with water 1
% Slurry. This slurry was made into paper by a Fourdrinier paper machine so as to have a basis weight of 170 g / m ² , impregnated with a 3 wt% aqueous solution of carboxyl-modified polyvinyl alcohol so as to have a solid content of 1.0 g / m ^2, and heated with hot air. After drying
After super calendering with a linear pressure of 90 kg / cm,
Corona discharge treatment was applied to both sides of the surface.

Next, the surface opposite to the image forming surface (back surface)
To, high density polyethylene (density 0.96g / cm ^3: M
I = 5) and low density polyethylene (density 0.92 g / cm
^The mixture of 1: 1 mixture of ³ : MI = 5) was used at a resin temperature of 330 ° C. using a melt extruder to have a thickness of 30 μm and a surface shape of J:
Rz and R as defined in IS B0601-1982
Coating was carried out by selecting an appropriate cooling roll so that the value of a becomes the value shown in Table 1. Then, on the final image forming surface (surface), anatase type titanium oxide 1
A low density polyethylene containing 3% (polyethylene density before pigment addition 0.92 g / cm ³ : MI = 5) was used at a resin temperature of 330 ° C. using a melt extruder at a thickness of 30 μm and a surface shape of Ra Appropriate cooling rolls were selected and coated so that the values were as shown in Table 1 to obtain a photographic support.

[0015] surface of the support, gelatin 4.5 g / m ^2, the ortho sensitized silver iodobromide in terms of silver nitrate containing 2.5 g / m ² as a binder, a silver halide emulsion layer Further, a protective layer containing 0.5 g / m ² of gelatin as a binder was simultaneously applied to the above layer, dried and conditioned to give a photographic paper. This photographic paper
It was wound at a tension of 20 kg / m, cut after sufficient dura- tion progressed, and a sample of photographic paper sheet was taken from the portion corresponding to the second lower winding of the winding where the gloss reduction was most remarkable.
This photographic paper sheet sample was exposed with a Macbeth RD519 reflection densitometer so that the reflection density would be about 1.9, and developed with Mitsubishi Paper Mills, Ltd.
℃ 90 seconds, 1% glacial acetic acid aqueous solution at 20 ℃ 60 seconds, Mitsubishi Paper Mills fixer Diamond Superfix 20
After developing, stopping and fixing at 300 ° C for 300 seconds, rinse with water for 10 minutes, let it air dry, and use the Murakami Color Research Laboratory's gloss meter GM-3D for an incident angle of 60 ° and a receiver aperture of 60 ° The gloss was measured. The results are shown in Table 1.

[0016]

[Table 1]

Emulsion surface gloss evaluation Grade 1: 92% or more (no problem) 2: 90% or more and less than 92% (no problem in practical use) 3: 85% or more but less than 90% (fog on the emulsion surface is recognized) 4: less than 85% (significant decrease in gloss is recognized)

[0018]

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a photographic support which does not cause a decrease in gloss due to the depressions formed on the surface of the emulsion layer of a photographic printing paper having a smooth surface quality. is there.

Continuation of front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location D21H 27/00

Claims (2)

[Claims] 1. A surface of a photographic support in which a paper containing a natural pulp and / or a synthetic pulp as a main component is used as a substrate, and both surfaces thereof are coated with a polyolefin resin (hereinafter, referred to as an image). JIS B0 of the surface shape of the surface shape on the side opposite to the image forming surface in the photographic support whose Ra value defined in JIS B0601-1982 is 0.20 μm or less.
The value of Rz defined by 601-1982 is 3.50 μ.
m or more and 5.50 μm or less, JIS B0601-
A photographic support characterized in that the Ra value defined in 1982 is 0.30 μm or more. 2. The photographic support according to claim 1, wherein the surface shape of the surface opposite to the image forming surface is J
The value of Ra defined in IS B0601-1982 is
A photographic support having a thickness of 0.55 μm or less.