JP3463839B2 - Photographic paper support and method for producing the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a support for photographic printing paper, and more specifically, it has excellent surface smoothness,
The present invention also relates to a support for photographic printing paper having a good surface texture.

[0002]

2. Description of the Related Art In recent years, as a support for photographic printing paper, waterproof photographic printing paper in which both surfaces of a paper substrate are coated with a hydrophobic resin, for example, a polyolefin resin, is used in order to automate and speed up development processing. As a result, the majority of the photographic printing paper support is now occupied, and the absorption of the front and back sides of the support with respect to the developing solution is prevented as compared with the conventional baryta paper. However, permeation from the cut surface of the edge cannot be prevented, resulting in a loss of value as a photograph. In addition, in order to achieve automation and speeding up, strong rigidity and strength are required for transportation in the processor during development.

When manufacturing such a support for photographic printing paper, there is a step of first making a paper base into paper. In this paper making step, pulp fibers are dispersed in water together with various chemicals, and a suspension thereof is prepared. It is the process of making paper with a net or round net and drying it to obtain a web. Therefore, during the papermaking process, the microorganisms propagate, and the microorganisms and their metabolites tend to agglomerate to produce slime, which is a viscous mud. If such slime becomes a certain size and peels off from the side wall of the wire part system, chest system, piping system, etc. and mixes into the paper stock, it causes stains and perforations on the paper substrate, or even paper breakage. This causes troubles such as stains and offensive odors of the apparatus, and has a great influence on the quality of the paper substrate and the operation during the paper substrate making.

In general, the support for photographic printing paper has the above-mentioned drawbacks on a paper substrate whose required quality is stricter than that of general paper, and of course, when coating a photographic emulsion, foreign matters, coloring matters, and photographic properties are excluded from the smoothness. It is necessary that there are almost no defects such as impurities that adversely affect the papermaking. For that purpose, it is necessary to prevent the slime from stopping at the papermaking stage as much as possible.

Further, one of the qualities of a support paper substrate for photographic printing paper is required to have good texture. On the other hand, in forming the formation, the factor of the raw material temperature occupies a large weight. The raw material temperature is generally affected by the temperature of the water, and changes to about 10 ° C to 40 ° C unless special measures are taken.
For formation, it is generally preferable that the raw material temperature is high.

However, as the temperature of the raw material rises, the number of defects of the paper substrate increases as the temperature rises, and the operation time until the defects occur tends to be shortened. Therefore, the continuous operability of is reduced.

As a method for preventing slime in the papermaking process, it is known that a bactericide called a slime control agent is added during the papermaking process to suppress bacteria such as bacteria causing slime or their growth. There is.

As the slime control agent, there are organic mercury agents, organic nitrogen agents, organic sulfur agents, organic bromine agents and the like. These slime control agents are used during the paper making process of the base paper substrate for photographic paper. When applied as it is, there is an adverse effect on photographic properties even if there is an effect of preventing the generation of slime, and there is a spot or fog on the photographic paper after development, which significantly impairs the quality of the product, Could not meet the demand of. Therefore, as a slime control agent suitable for photography, JP-A-59-59
Japanese Patent No. 1285437 proposes a morpholine slime control agent. In addition, JP-A-59-1
Japanese Patent No. 31929 proposes 5-chloro-2-methyl-4-isothiazoline and the like as a thiazoline-based slime control agent, but it was not sufficient in terms of the slime-preventing effect.

[0009] Regarding the drawbacks of conventional paper substrates, slime is often the cause, and it is often solved by adding a slime control agent or the like, but this slime control agent does not reduce the drawbacks. No ninhydrin reaction to the protein produced from slime was observed. However, analysis of this slime detected a dozen times as many alkylketene dimer size agents as usual.

As described above, even when the conventionally used slime control agent is used, the defects of the paper substrate cannot be eliminated unless the machine is stopped for a long period of operation and removed by cleaning in the papermaking process. Further, the conventional slime control agent having a bactericidal action has almost no effect for the purpose of preventing the occurrence of defects in the paper substrate, and in such a case, the alkyl ketene dimer sizing agent must be reduced in amount. This is not a preferable direction because it adversely affects the size as a support for photographic printing paper. The alkyl ketene dimer sizing agent is used in consideration of the addition amount and its effect, but the addition amount is 0.3 to 0.1 per pulp in order to prevent permeation of the treatment liquid from the end. 4%
It also becomes.

The alkyl ketene dimer sizing agent is usually added to the paper substrate as a sizing agent in order to prevent edge stains due to permeation of the processing liquid from the end of the photographic paper support. For example, JP-A-57-185432
Japanese Patent Laid-Open Publication No. Sho 5 (1999) -58242 discloses a method of adding an alkyl ketene dimer size agent and a cationic polyacrylamide.
No. 7-197539, a method of using an alkylketene dimer size agent in combination with a cationic and anionic polyacrylamide, and JP-A-2-223945, a method of using an alkylketene dimer sizing agent having a specific composition. Is disclosed. However, these publications do not disclose at all the relation between slime and alkyl ketene dimer, which are the cause of the defects of the paper substrate, and have not been solved up to now, and have reached the present.

In recent years, for the purpose of rapid development of photographic printing paper, a water-resistant photographic printing paper support in which both surfaces of the paper are coated with a polyolefin such as polyethylene is preferably used. The support for photographic printing paper, in which both sides of this base paper are coated with polyolefin, has a glossy surface, or has a matte or silk pattern on the surface. It is preferable that the surface has no gloss and has a smooth glossy surface, and particularly that the surface has a mirror-like smooth surface with as few fine irregularities as possible.

In order to obtain such a smooth support, for example, in Japanese Patent Laid-Open No. 60-67940, the base paper constituting the support has a void volume of 0.4 μm or less of 0.04 ml.
Use of pulp / g or more, JP-A-60-696
In Japanese Patent Publication No. 49, a wood pulp having an average fiber length of 0.4 to 0.9 mm, an average fiber width of 13.5 μm or more and an average fiber thickness of 4 μm or less is used. Mixing 5 to 60% of hydrophobic fibers with pulp, or limiting the dehydration conditions when obtaining wet paper from pulp slurry with a two-wire paper machine in JP-A-61-284762. Methods and the like are disclosed.

It is also possible to calender the base paper between metal rolls and increase the pressure at this time, that is, the pressure of the machine calender to increase the density of the base paper used as the support for photographic printing paper. Has been done. On the other hand,
For coating polyolefins such as polyethylene, an extrusion coating method, that is, a method in which a polyolefin melted at high temperature is cast on the surface of a base paper for coating is used. In order to improve the smoothness, measures such as increasing the thickness of the coated polyolefin layer and increasing the pressing pressure when coating the polyolefin have been taken. However, the effect of the above measures when coating the polyolefin is small, and there is a problem that it is also disadvantageous in terms of cost. On the other hand, the above method of increasing the density of the base paper also causes a poor appearance such as blacking and paper beading. However, a sufficiently satisfactory smooth support for photographic printing paper has not been obtained by any of the methods.

Further, a filler is added to the support paper substrate for photographic printing paper.
A method containing (or called a pigment) has also been filed. For example, JP-A-56-43637 discloses that
Disclosed is a photographic paper in which at least one of a weak acid salt of magnesium, calcium or zinc or an oxide thereof is added to a paper material to eliminate adverse effects on photographic properties due to an additive chemical such as a paper strengthening agent and a sizing agent. ing. Also,
JP-A-63-20748 discloses that a basifying agent consisting of an alkali metal hydrogencarbonate is converted to sodium hydrogencarbonate in an amount of 0.5 to 2.0% by weight based on the dry weight of pulp.
It is also disclosed to prevent edge stains due to invasion of a developing solution by using a pulp base paper made from a pulp slurry contained in the range of. However, none of the methods positively aims to improve the surface quality of the support for photographic printing paper.

[0016]

DISCLOSURE OF THE INVENTION The object of the present invention is that in a paper-base papermaking system using an alkylketene dimer sizing agent, many defects of the paper base occur in a short time when the raw material temperature rises. In addition, when the raw material temperature is lowered and papermaking is performed, a problem occurs in the uniform formation which is the quality of the base material of the photographic printing paper support. In order to provide a photographic support paper substrate without defects, there is a method of cleaning the paper making process, but with this method, the operating rate of the paper machine is lowered, continuous operation cannot be performed, and other quality items such as There will be a lack of stability. Therefore, an object of the present invention is to provide a support paper for photographic printing paper which is excellent in production suitability and a method for producing the same, without causing the above deterioration of texture.

[0017]

A support for photographic printing paper according to the present invention comprises a paper substrate and coating layers formed on both sides of the substrate and containing a polyolefin resin as a main component. Is an alkyl ketene dimer having a melting start temperature of 35 ° C. or higher and a melting point of 50 ° C. or higher. For paper stock, 0.1-
It is achieved by containing 0.5%.

The photographic printing paper support of the present invention is characterized in that a pigment layer is provided on at least one side of a paper base, both sides of which are coated with a polyolefin resin, and an adhesive is applied to at least one side of the paper base. The smear layer containing 5 to 20 g / m ²
Alkyl ketene containing natural pulp as a main component in the paper base, having a particle size of 3 μm or less with respect to the paper material in an amount of 1.0 to 7.0% by weight, and having a melting point of 50 ° C. or more. This is achieved by the density of the paper substrate containing the dimer of 0.1 to 0.5% by weight being 0.90 or more, and the SRa of the smear layer and the surface of the paper substrate before smearing being 1.5 μm or less.

Further, according to the present invention, in a method for producing a support for photographic printing paper in which at least one surface of a paper substrate is coated with a resin containing a polyolefin resin as a main component, the paper substrate is formed into a Fourdrinier paper web. When forming with a two-wire paper machine equipped with an endless upper wire that sandwiches the wire and the web from above, the solid content concentration of the paper just before being sandwiched by the upper wire is 1.5 to 2.5 weight. % Of the amount of water dewatered by the upper endless wire and the amount of water dewatered by the lower wire of the Fourdrinier in the part sandwiched between the upper wire and the lower Fourdrinier wire. The upper dehydration rate, which is the ratio of the amount of water dehydrated by the upper endless wire to the total amount, is set to 30 to 50%, and the paper base obtained is made to have an absolute dry water content of 2.0 to 7.0%. Papermaking, and A photographic printing paper substrate produced by heat calendering the base paper through a nip formed by two metal rolls under conditions of a temperature of 110 ° C. to 250 ° C. and a linear pressure of 40 kg / cm or more. It is achieved by the manufacturing method of.

Furthermore, the present invention is a method for producing a support for photographic printing paper in which both sides of a paper substrate are coated with a polyolefin resin by a melt extrusion coating method, when the polyolefin resin on the emulsion coated side is extrusion coated, Cooling roll and press roll 30 ~ 100k with backup roll pressurized by hydraulic cylinder
This is achieved by a manufacturing method in which the molten polyolefin resin is cooled and solidified while being nipped with a linear pressure of g / cm and the bending of the cooling roll is 0.1% or less with respect to the roll surface length.

The present invention relates to a method for producing a support for photographic printing paper in which both sides of a paper substrate are coated with a polyolefin resin by a melt extrusion coating method, wherein a hydraulic cylinder is used when extrusion coating the emulsion resin side polyolefin resin. Intervening a backup roll pressurized by
The cooling roll surface has a ten-point average roughness Rz on a flat metal surface.
Has fine irregularities of 0.3 to 1.0 μm and an average pitch of 10 to 50 μm, the tops of the protrusions are flat, and the average inclination angle on the bottom side from the average line of the recesses is 5 to 7 degrees. The average inclination angle on the top side from the average line of the recesses is 2 to 4 degrees, and the edges of the flat portion and the recesses are smooth. The cooling roll and the press roll have a line of 30 to 100 kg / cm. This is accomplished by a method for producing a support for photographic printing paper, which is nipped by pressure and the molten polyolefin resin is cooled and solidified while the bending of the cooling roll is 20 μm or less.

The present invention will be described in detail below. The melting start temperature and melting point referred to in the present invention refer to JIS K7121.
It is obtained by a DSC (differential thermal analyzer) according to the method for measuring the transition temperature of plastics specified in 1. The melting start temperature and melting point will be described. DSC
From the curve, the melting point is the temperature at the top of the melting peak. Similarly, the melting onset temperature is a straight line obtained by extending the low temperature side baseline to the high temperature side by the DSC curve and a tangent line drawn at the point where the gradient becomes maximum on the low temperature side curve of the melting peak. It is the temperature at the intersection. In the present invention, when two or more melting peaks appear independently, the melting point is the peak on the low temperature side. In the present invention, 35 ° C
An alkyl ketene dimer sizing agent having the above melting start temperature and a relatively high melting point of 50 ° C. or higher must be used.

The cause of the defects that occur in the paper substrate in the present invention is not clear, but is presumed as follows. Microorganisms use sugars in white water as a nutrient source, mainly bacteria grow, and produce sticky substances such as light yellow, light brown, pink, and red, which are used as binders, microorganisms, or An slime complex is formed by incorporating an organic or inorganic substance such as an alkyl ketene dimer sizing agent. Worse, alkyl ketene dimer sizing agents develop tackiness with increasing temperature,
It is believed that the slime complex of the slime and the alkyl ketene dimer size agent is formed to be larger. Such slime-alkyl ketene dimer complex is
If it adheres to white water pits or stock inlets and falls off due to the flow rate, it adheres to the paper, causing defects in the paper substrate. This slime complex is often found in places where there is no flow velocity, such as dead spaces or dead corners.

In the present invention, the alkyl ketene dimer sizing agent has a melting start temperature of 35 ° C. or higher and a melting point of 50.
It is preferable to use an alkylketene dimer sizing agent having a melting start temperature of 42 ° C. or higher and a melting point of 58 ° C. or higher at a temperature of not lower than ° C. as a result,
By using the conventional slime control agent, rather than suppressing the growth of microorganisms or preventing the occurrence of slime by sterilizing, reduce the stickiness of the alkyl ketene dimer sizing agent, and reduce the slime and alkyl ketene dimer sizing agent. It is considered that, by dispersing the composite of (1), re-adhesion was prevented and defects occurring on the paper substrate were prevented, so that a remarkable effect as compared with the conventional case was obtained. Furthermore, it is effective to prevent the slime and the alkyl ketene dimer sizing agent from adhering to a place such as a dead space or a dead corner where there is no flow velocity by Teflon processing, because the formation of a complex is prevented. It is a means.

On the other hand, when an alkylketene dimer sizing agent having a melting onset temperature lower than 35 ° C. or a melting point lower than 50 ° C. is used, the slime is bonded to the alkyl ketene dimer sizing agent. Becomes remarkable and the slime-alkyl ketene dimer complex is formed and greatly promoted, resulting in the occurrence of defects in the paper substrate as described above. Also,
To make matters worse, failure points will occur sooner, not only poor operability, but also the occurrence of the above-mentioned defects will occur, and the shape of the failure point will become larger, so the failure point in terms of quality will increase. However, the practicality of the support substrate for photographic paper is completely lost. In particular, when the melting start temperature is lower than 35 ° C., the components of the alkylketene dimer sizing agent having a melting point or less increase, and therefore these tendencies become remarkable.

The alkyl ketene dimer sizing agent used in the present invention has a melting start temperature of 35 ° C. or higher and a melting point of 50 ° C. or higher, and therefore has a relatively high melting point. As a method of increasing the melting start temperature or melting point of the alkyl ketene dimer sizing agent, the content of the alkyl group having a small number of carbon atoms that constitutes the alkyl ketene dimer sizing agent is reduced or the content of the alkyl group having a large number of carbon atoms is increased. Then, a method of increasing the melting start temperature or melting point of the sizing agent itself or a method of encapsulating a low melting point material to improve temperature resistance performance, etc. is considered, but in the present invention, the means for those methods is It can be used as long as there is no problem in photographic quality.

Further, in the present invention, since the temperature to be measured changes depending on the conditions such as the paper machine or pulp preparation,
In the present invention, after the alkyl ketene dimer sizing agent is added,
In the papermaking process such as wire part system, chest system, or piping system, the temperature at the highest temperature is 3
It is controlled at 0 ° C to 50 ° C.

If the temperature is lower than 30 ° C., the water drainage from the wire part system is poor, and the texture of the paper substrate produced is poor. Further, as a result of poor drainage, the drying load on the dryer part system increases, which increases energy cost and is not practical. Even a photographic printing paper in which both surfaces of these paper substrates are coated with a polyolefin resin and emulsion is applied is not suitable for practical use due to poor texture.
Further, the poor texture not only affects the coatability of the emulsion, but is also reflected in the gloss of the emulsion surface. Further, when the papermaking is carried out at a temperature of higher than 50 ° C., the drainage property is excessively improved, resulting in poor texture, resulting in poor surface quality as a support for photographic printing paper and loss of practicality.

As the filler to be used in the present invention, clay, kaolin, calcium carbonate, barium sulfate, titanium oxide, aluminum hydroxide and magnesium hydroxide are used. They may be combined or added. As a preferable filler, calcium carbonate having a high whiteness and being bulky when used as a paper substrate is preferable. Particularly preferably,
Light calcium carbonate produced by chemical synthesis is good. Light calcium carbonate has the same chemical composition as heavy carbonic acid, but completely different physical properties, especially particle shape and particle size. Light calcium carbonate can change the shape and size of crystals. There are many types of light calcium carbonate in particle shape and particle diameter, and they are classified according to the purpose of use. For example, there are synthetic calcite spindle type, constitutive calcite cubic type, synthetic aragonite columnar type, synthetic vaterite spherical type and the like.

In the present invention, the filler has a particle size of 3.0 μm.
m or less, preferably the major axis is 3.0 μm or less and the minor axis is 1.0 μm or less. Further, the addition amount thereof is 1.0 to 7.0% by weight based on the dry weight of pulp,
Preferably, 2.0 to 5.0% is added. When the particle size of the filler exceeds 3.0 μm, the unevenness due to the agglomeration of the filler becomes large, the texture is deteriorated as a support base paper for photographic printing paper, the smoothness of the surface is lost, and the polyolefin resin is applied on the base paper. Even if it is applied, if it is a mirror type photographic printing paper,
The emulsion gloss decreases, and in the case of the mold type, uneven coating of the emulsion occurs and the practicality is lost. When the amount of the filler added is 7.0% by weight or more based on the dry weight of pulp, the smoothness is improved, but the rigidity is lowered, and the support for photographic paper is used as a support for photographic paper during development processing. If the amount of filler added is 1.0% by weight or more based on the dry weight of pulp, smoothness and surface texture will be improved. No effect is observed.

The base paper used in the practice of the present invention may be ordinary natural pulp paper, synthetic fiber paper, or so-called synthetic paper obtained by quasi-synthesizing synthetic film, but it is a combination of softwood pulp, hardwood pulp and softwood hardwood. Natural pulp paper based on wood pulp is preferably used.
The thickness of the base paper is not particularly limited, but the basis weight is preferably 50 to 350 g / m ² .

In the present invention, sizing agents such as rosin, soap, wax, and synthetic sizing agents are added to these natural pulps.
A photographic support is manufactured by using a base paper containing a band, a fixing agent such as aluminum chloride and a filler such as clay, talc, calcium carbonate and the like as a base paper, and a material having high rigidity and good surface quality can be obtained. Further, when a base paper for photographic printing paper is used as the base material, one having better surface quality can be obtained.

The base paper for photographic printing paper used in the present invention may contain various polymer compound additives. For example, as a dry paper strengthening agent, cationized starch, cationized polyacrylamide, anionized polyacrylamide, carboxy-modified polyvinyl alcohol,
Gelatin and the like, fatty acid salts, rosin derivatives, dialkylketene dimer emulsions, petroleum resin emulsions, ammonium salts of styrene-maleic anhydride copolymer alkyl ester, as pigments, and clay, kaolin, calcium carbonate, barium sulfate as pigments. , Titanium oxide, etc., as a wet paper strength enhancer, such as melamine resin, urea resin,
Epoxidized polyamide resin, polyvalent metal salts such as aluminum sulfate and aluminum chloride as a fixing agent, cation-modified polymers such as cationized starch, etc. as pH adjusters, sodium hydroxide, sodium carbonate, hydrochloric acid, etc., inorganic electrolytes such as sodium chloride , Glauber's salt, etc., as well as dyes, optical brighteners, latexes, etc. can be appropriately combined and contained.

In the support for photographic printing paper of the present invention, when a smear layer is provided on a paper base, the density of the paper base is 0.9.
Must be 0 or greater. If it is less than 0.90, a photographic printing paper support substrate having a satisfactory level of smoothness can be produced. However, these substrates are coated with a polyolefin resin to provide a photographic printing paper support. In that case, no matter how hard the smear layer is, even if it is fixed on the paper substrate, when it is laminated at a high nip when coated with a polyolefin resin, the base paper easily undergoes thermal deformation, so as a support for photographic printing paper, The texture of the paper substrate itself is formed on the surface of the resin layer, which not only lowers the gloss of the emulsion surface, but also markedly lowers the surface texture and gloss feeling by visual observation.

Usually, as the paper base of the support for photographic printing paper, paper having particularly excellent smoothness is used. However, in the present invention, when a smear layer is provided, a paper base which is not excellent in smoothness is also used. However, in the present invention, the dry weight of the smear is 5 to 20 g / m ² , the density of the paper substrate is 0.90 or more, and the central surface average roughness of the smear layer and the paper substrate surface. (Hereinafter referred to as SRa) needs to be 1.50 μm or less.

In the present invention, the smear amount is 5 to 5 dry weight.
It is 20 g / m ² , and the higher the amount of smear, the more the rigidity tends to be improved when used as a photographic support, but the range of 5 to 10 g / m ² is preferable in terms of operability and quality. . When the smear amount is less than 5 g / m ² , there is no effect of improving the surface quality, and there is little improvement in rigidity. Further, when the smear amount exceeds 20 g / m ² , the degree of thermal deformation of the smear layer becomes large at the time of coating with the molten oriolefin resin and the surface quality deteriorates, so that the effect of improving the surface quality is lost.

When the SRa of the smear layer is 1.50 μm or more, the emulsion gloss as a mirror surface type cannot be obtained,
Practicality is lost. When SRa on the surface of the paper substrate before forming the smear layer is 1.50 μm or more, when the smear layer is coated with the molten polyolefin resin, even if the smear layer is not deformed, the paper is heated by heat. The substrate itself is deformed, resulting in the formation of the texture of the paper substrate itself being emphasized, the surface quality is remarkably deteriorated, and even if an emulsion is applied to these photographic paper supports, the glossy appearance is apparent. Is not only deteriorated, but also small irregularities are generated on the entire surface, the surface quality as photographic printing paper is lost, and the practicality is lost.

Next, the smear layer according to the present invention will be described. Examples of the adhesive used in the present invention include casein, soybean protein methanol, proteins such as proteins extracted from monocytoplasmic cells such as acetic acid, gelatins, styrene, etc.
A butadiene copolymer, a conjugated diene polymer latex such as methyl methacrylate / butadiene copolymer, a polymer of acrylic acid ester and / or methacrylic acid ester, or an acrylic polymer latex such as a copolymer,
Vinyl-based polymer latex such as ethylene / vinyl acetate copolymer, or an alkali-soluble or alkali-insoluble polymer latex obtained by functionally modifying these various polymers with a functional group-containing monomer such as a carboxyl group, Synthetic resin adhesives such as olefin / maleic anhydride resins and melamine resins, positive starch, phosphate esterified starch, starches such as oxidized starch, cellulose derivatives such as carboxymethyl cellulose, hydroxyethyl cellulose, etc. Are used alone or in combination.

In the present invention, in addition to the above-mentioned adhesives, if necessary, various orientations and organic pigments such as clay, aluminum hydroxide, calcium carbonate, titanium dioxide, barium sulfate, zinc oxide, satin white, plastic pigments, etc. One or more of the common smearing pigments of are used. Further, as an auxiliary agent, a defoaming agent, a colorant, a releasing agent, a fluidity improving agent, etc. may be appropriately used, if necessary.

The smear composition containing an adhesive or pigment in the present invention is a blade coater, an air knife coater, a roll coater, a brush coater, a curtain coater, a chanplex coater, a bar coater, which is used in the production of general smear paper. An on-machine or off-machine coater equipped with a smearing device such as a gravure coater or a size press coater is used to coat the base paper in one or more layers.

The high-smoothness smear paper used in the present invention may have a high gloss like ordinary cast smear paper, but in the present invention, the high-smoothness smear paper is used as a base paper and a polyolefin resin layer is formed thereon. Since it is provided, it is not necessary to have strong gloss and it is sufficient if it has high smoothness.

In order to obtain a paper substrate having a surface texture defined in the present invention, the paper substrate is provided with a wire forming a web of a Fourdrinier paper machine and an endless upper part so that the web is sandwiched from the wire. When forming by a two-wire paper machine provided with a wire, the solid content concentration of the web just before being sandwiched by the upper wire is 1.5 to 2.5% by weight, and the fourdrinier paper machine of the upper wire and the lower part Amount of water dewatered by the upper endless wire and the amount of water dewatered by the lower wire of the Fourdrinier in the part sandwiched between the wires It is manufactured by setting the upper dehydration rate which is the ratio of 30 to 50%.

In the present invention, when a paper substrate is formed by a two-wire paper machine in which a wire for forming a web of a Fourdrinier paper machine and an endless wire for sandwiching the web from above are provided on the paper substrate, Immediately before the stock is sandwiched between the upper endless wires, the solid content of the web needs to be 1.5 to 2.5% by weight. Regarding the formation most closely related to the surface texture of the paper substrate, if the solid content concentration is less than 1.5%, the improvement effect is not exerted in the part sandwiched by the upper wires, and the desired surface texture cannot be obtained. . A support for photographic printing paper using this paper substrate causes grain-like flickering and results in poor printed surface quality. When the solid content concentration of the web just before being sandwiched by the upper wire exceeds 2.5%, the formation already formed in the portion sandwiched by the upper wire is destroyed and the formation is deteriorated. As a result, the desired surface texture cannot be obtained. The support for photographic printing paper using this paper substrate also causes wrinkle-like flickering, resulting in poor printed surface quality.

Further, when forming a web by a two-wire paper machine in which a paper base is provided with a wire forming a web of a Fourdrinier and an endless wire sandwiching the web from above, the upper wire is used. Upper endless wire to the total amount of water dewatered by the upper endless wire and the amount of water dewatered by the lower wire of the Fourdrinier in the part sandwiched between the wire of the lower and fourdrinier The upper dehydration rate, which is the ratio of the amount of water dehydrated in, needs to be 30 to 50%. If the upper dehydration rate is less than 30%, the effect of homogenizing the sandwiched webs in the thickness direction is small and the desired surface texture cannot be obtained. As described above, the support for photographic printing paper using this paper substrate also has poor printed surface quality and cannot attain its purpose. When the upper dehydration rate exceeds 50%, the strength of the paper layer is lowered, which causes a problem on the suitability of the photographic printing paper such as the formation of blisters between the polyolefin resin and the paper substrate during operation. Further, wire marks are more likely to appear, which is reflected on the surface of the photographic printing paper support, and the surface quality of the photographic printing paper is impaired.

Further, the surface texture is dominated by minute irregularities on the surface of the raw paper. That is, the fine irregularities on the surface of the raw paper remain on the surface of the support for photographic printing paper even if they are covered with the polyolefin resin layer, and the irregularities reduce the glossiness. Since the concave portion of the large waviness unevenness is not processed, the fine unevenness in this concave portion must be eliminated. Moreover, the surface texture can be improved by completely eliminating the large undulations. The linear pressure and temperature of a machine calender or a thermal calender are raised to crush the unevenness of the large undulations on the base paper surface, but this reduces the bulkiness of the base paper and lowers the rigidity. In addition, heat generated when the polyolefin layer is applied may cause unevenness to be reproduced due to "back" of the base paper, and thus the surface texture cannot be improved by simply crushing.

In the present invention, the surface quality is further improved by performing the thermal calendar treatment. Since the thermal calender performs pressure treatment by passing the base paper between the metal rolls, the convex portions of the large waviness irregularities on the surface of the raw paper are processed, and the fine irregularities on the convex portions disappear. As a result, the emulsion gloss of photographic printing paper does not become uneven, and the overall glossiness increases,
The surface quality level of the photographic printing paper support of the present invention is remarkably improved.

Further, as a condition for heat calendering the paper substrate, a linear pressure of 100 to 200 kg / cm and a metal roll temperature of 110 ° C. or higher, preferably 150 to 200 ° C. are used to produce the desired base paper. It became clear that it was easy. If the temperature is below this temperature, the base paper will not be sufficiently smooth, and if it exceeds 200 ° C, the bulk of the paper substrate tends to decrease, and the rigidity tends to decrease. In other words, the thermal calender in the present invention is one in which the raw paper penetrates at a right angle into the nip portion composed of the metal roll and the metal roll, does not require equipment such as a super calender, and treats only the surface without reducing the bulk. is there.

Further, in the present invention, the surface roughness of the metal roll is preferably 0.3 S or less. If the surface roughness is above the above range, the pattern of the unevenness of the roll is transferred to the surface of the base paper, and the emulsion gloss is lowered.

The position to be subjected to the thermal calendar treatment in the present invention may be before the size press of the paper machine or after the size press and after passing through the after-dryer. A machine calender is usually installed after the after-dryer to wind the base paper, but the machine calender may be used instead of the machine calender, and the machine calender may be connected before and / or after the machine calender. Further, the winding of the base paper wound by the paper machine may be processed off-machine. Further, in the step of coating with resin, thermal calendering immediately before the laminator is more effective because of less blistering. Further, it is preferable that the running base paper penetrates at a right angle to the nip pressure.

In the heat calendering process consisting of two heated metal rolls, the paper base is pressed at a linear pressure of 40 kg / cm or more at the time of nip. The elastic roll is deformed without being damaged. In other words, the pressure at the beginning of the nip reduces the unevenness of the large undulations of the base paper to some extent, and even though the unevenness of the large undulations remains on the base paper without being crushed, the nip pressure is evenly applied. It is possible to reduce the fine irregularities present in the large undulations on the surface of the base paper. At this time, by performing a thermal calendering treatment comprising two heated metal rolls of the present invention, the density used is more uniform and the energy used to crush it to the same hardness as the roll is reduced. Therefore, by reducing the pressure and heating, on the smooth metal roll surface heated while maintaining the rigidity of the initial base paper, the ironing effect efficiently crushes the fine irregularities of the surface and the bulkiness is high. A smooth base paper is obtained, and after that, it is coated with resin and then emulsion-coated to give a good glossy feeling when used as a photographic printing paper.

In the present invention, by the extrusion coating method,
When the molten polyolefin resin is coated on the paper substrate, the cooling roll and the press roll are 30 to 100 k apart with the backup roll pressurized by the hydraulic cylinder interposed.
It is required that the linear pressure is g / cm, and the bending of the cooling roll is 0.1% or less with respect to the roll surface length. Nip between cooling roll and press roll is 30kg /
If it is less than cm, a large number of fine crater-like pores are generated on the polyolefin resin coated surface, and even if an emulsion is applied on the resin surface, a fine shape remains and the emulsion surface is flickered. Occurs and has a fatal defect as a photographic printing paper. On the contrary, 100 kg
When it is nipped in excess of / cm, it is fixed on the surface of the polyolefin resin while the formation on the paper substrate is emphasized, so that the surface texture is remarkably deteriorated and it cannot be put to practical use.

Further, in the present invention, not only the cooling roll and the press roll are subjected to a linear pressure of 30 to 100 kg / cm, and the bending of the cooling roll must be 20 μm or less. When the bending of the cooling roll is more than 20 μm, when the molten polyolefin resin is solidified by the cooling roll at a relatively high nip as in the present invention, no matter how many crowns are attached to the backup roll, the backup roll may have a specific portion in the surface length direction. Many fine crater-like pores are generated,
Even if an emulsion is applied on the surface of this resin, a fine shape remains, causing a trouble that the emulsion surface is flickering, and has a fatal defect as a photographic printing paper.

The photographic support of the present invention is manufactured by melting and extruding a polyolefin resin on a paper substrate, nipping it with a press roll and a cooling roll, and cooling and solidifying. Generally, a cooling roll has a structure in which a cylindrical roll (called a spiral jacket) in which fins for cooling water flow paths are spirally provided is inserted into a cylindrical roll (called an outer shell). It has a structure that can take out. Therefore, since the inner surface of the outer shell cannot be closely attached to the fin end of the spiral jacket, only the outer shell receives the pressure applied by the press roll.

According to the present invention, when extrusion coating is performed even when the outer shell is nipped with a high linear pressure, the outer shell is a press roll that is nipped through a backup roll pressurized by a hydraulic cylinder. No strain or flexure occurs in the wire, and the linear pressure applied to the cooling roll by the press roll becomes uniform, so crater-like pores on the surface of the resin coating layer, which is considered to be caused by entrainment of entrained air, no longer occur. I think that. Moreover, as a result of controlling this deflection to 20 μm or less, it is not necessary to increase the thickness of the outer shell and increase the strength of the shell more than necessary. Further, it becomes possible to uniformly perform heat exchange between the molten resin and the cooling roll in the roll width direction without increasing the thickness of the outer shell and reducing the thermal conductivity of the outer shell. In particular, the thermal conductivity of the void portion between the fin end portion and the inner surface of the outer shell is improved, and the peeling property between the cooling roll and the resin coating surface that has been cooled and solidified is improved. It is considered to be something.

Usually, the support for photographic printing paper is coated with the polyolefin resin melted by the extrusion coating method by solidifying with the cooling roll continuously by the take-up roll of the photographic printing paper base as in paper products. . Therefore, since the operation is performed continuously, a seam is generated between the winding rolls of the photographic printing paper substrate. When passing this seam,
It is normal to lower the nip pressure due to the increased thickness. Therefore, up to about 300 m minutes immediately after production after passing between the cooling roll and the press roll, many crater-like pores are generated, an unusable part is produced as a product, and loss is very large, especially when pressurized with an air cylinder. This tendency was remarkable when manufactured by the following method. By using the hydraulic cylinder of the present invention, it is possible to drastically reduce crater-like pores. The reason for this is that, in the air cylinder by air pressure, there is a time lag until the nip pressure between the cooling roll and the press roll recovers after passing the joint, and it is considered that the crater-like pores are deteriorated. It is considered that the nip formed by the cylinder is mechanically instantaneously pressed to eliminate the time lag, and the crater-like pores are drastically reduced after passing through the joint.

Finally, the cooling roll used in the present invention will be described in detail. First, the roughness parameter used in the present invention will be described. The ten-point average roughness Rz is the portion from the cross-section curve that is extracted from the reference length, parallel to the average line, and from the highest to the fifth summit measured from the straight line that does not cross the cross-section curve in the longitudinal magnification direction. The value of the difference between the average value of the altitude and the average value of the altitudes of the valley bottoms from the deepest to the fifth is expressed in micrometers (μm). It can be stopped by the following formula 1 and JIS B0601-1982 (Japanese Industrial Standard) Stipulated in.

[0057]

[Equation 1]

R ₁ , R ₃ , R ₅ , R ₇ , and R ₉ are the top to fifth peaks of the extracted portion corresponding to the reference length, and R ₂ , R ₄ , R ₆ , R ₈ , and R ₁₀ is the deepest to fifth valley bottom of the extracted portion corresponding to the reference length.

Further, the average pitch is the distance from the point from the peak to the valley to the crossing point from the next peak to the valley across the average line in the portion where the reference length is extracted from the roughness curve, Smi. Then, if the total number of intervals is N, the following expression 2 holds and is defined in ISO 4287/1 (international standard).

[0060]

[Equation 2]

Further, the average inclination angle of the unevenness is obtained from the following expression 3 from the height and depth of the average line from the roughness curve and the length of the bottom side.

[0062]

[Equation 3]

H ₁ is the height from the average line to the top and the depth from the average line to the bottom, and L ₁ is the height and the length of the bottom of the depth.

If both sides of the sheet-like substrate are coated with a polyolefin resin and the ten-point average roughness Rz of the surface of the resin coating layer on the side where the photographic emulsion layer is provided is less than 0.3 μm, a satin finish, which is a quality defect, may occur. It deteriorates and the surface of the emulsion is flicker diffusely reflected, and its value as a photographic printing paper is lost. Also, 1.0
When it exceeds μm, the image clarity is deteriorated, the gloss as a glossy type photographic printing paper is deteriorated, and the practicality is lost.
If the average pitch is less than 10 μm, the unevenness of the peeling lateral step is deteriorated, and if the average pitch is more than 50 μm, waviness occurs on the surface after coating the emulsion and the image clarity is deteriorated. If the bottoms of the recesses are not flat, coating unevenness will occur at the start of emulsion coating. When the average inclination angle on the top side from the average line of the convex portions is less than 5 degrees, the satin finish is deteriorated and the average inclination angle is 7 degrees.
If it exceeds the above range, it becomes difficult to reduce the layer thickness at the start of emulsion coating. When the average inclination angle on the bottom side from the average line of the convex portion is less than 2 degrees,
When the peeling lateral unevenness worsens and the average tilt angle exceeds 4 degrees,
Practicality is lost because it is difficult to reduce the layer thickness at the start of emulsion coating.

In the present invention, it is easy to prevent peeling lateral unevenness and crater-like pores by increasing the roughness of the surface of the cooling roll used for the extrusion coating of the resin-coated photographic support, By increasing the roughness, it is not possible to make a thin layer at the start of emulsion coating, and the image clarity of the emulsion surface is reduced, which causes conflicting problems.
It is necessary to obtain the optimum shape. Therefore, as a result of conducting studies using cooling rolls having various roughnesses and irregular shapes, the concave and convex portions on the surface of the resin-coated photographic support of the present invention are flattened, and the edges of the flat and convex portions are By smoothing the part, it was possible to achieve a thin layer at the start of emulsion coating.

In addition, in the extrusion coating method in which a polyolefin resin is applied on both sides of a sheet-like substrate and the polyolefin layer is cooled and solidified while being pressed against a cooling roll, the side on which the photographic emulsion layer is provided is a resin-coated photographic support. If the 10-point average roughness Rz of the cooling roll is less than 0.3 μm, the satin finish, which is a quality defect, deteriorates, the surface of the emulsion scatters, and the value as a photographic printing paper is lost. On the other hand, when it exceeds 1.0 μm, the image clarity is deteriorated, the gloss as a glossy type photographic printing paper is deteriorated, and the practicality is lost. If the average pitch is less than 10 μm, the unevenness of the peeling lateral step is deteriorated, and if the average pitch is more than 50 μm, the satin finish is deteriorated, and waviness occurs on the surface after emulsion coating, and the image clarity is deteriorated. If the bottom of the recess is not flat,
Coating unevenness occurs at the start of emulsion coating. When the average inclination angle from the average line of the convex portions to the top side is less than 5 degrees, the satin finish deteriorates, and when the average inclination angle exceeds 7 degrees, it becomes difficult to thin the layer at the start of emulsion coating. When the average inclination angle from the average line of the convex portion to the bottom side is less than 2 degrees, the peeling lateral unevenness becomes worse, and when the average inclination angle exceeds 4 degrees, it becomes difficult to thin the layer at the start of emulsion coating and it is practical. Is lost.

The thermoplastic resin used in the resin layer of the photographic support in the present invention includes polyolefin, polystyrene, polyvinyl chloride, polyacrylic acid ester,
Homopolymers such as linear polyesters such as polyethylene terephthalate, polycarbonates, polyamides such as nylon, cellulose esters, polyacrylonitrile, or copolymers such as ethylene-vinyl acetate copolymers and mixtures thereof, which are resin films on a base paper. Any resin can be used as long as it can be coated, but in particular, thermoplastic resins such as polyolefin, polystyrene, polyethylene terephthalate, and polyvinyl chloride are preferable, and among them, the polyolefin resin has good extrudability and adhesiveness with base paper. It is particularly advantageous in terms of price, etc.

The polyolefin resin used in the present invention is a homopolymer such as low density polyethylene, medium density polyethylene, high density polyethylene, polyphenylene, polybutene or polypentene, or two or more olefins such as ethylene-propylene copolymer. The copolymers and the mixtures thereof having various densities and melt viscosity indexes (melt indexes: hereinafter simply abbreviated as MI) can be used alone or as a mixture thereof. Also,
Linear low density polyethylene, which is a copolymer of ethylene and α-olefin, and a mixture of these with various polyolefins can also be used.

In order to produce a photographic support, a resin is dissolved in a solvent and smeared on the surface of the base paper, so that it can be carried out by solvent smearing or a laminating method in which a resin film is bonded to the surface of the base paper. The support for use is manufactured by subjecting a resin composition containing titanium dioxide, which is heated and melted, to a base paper which is normally traveling, by film-shaped melt extrusion coating from a slit die. When the resin is a polyolefin resin, the melt extrusion temperature is preferably 200 to 350 ° C. Further, it is preferable that the base paper is subjected to an activation treatment such as a corona discharge treatment or a flame treatment before the resin composition is melt-extrusion coated onto the base paper. The thickness of the resin layer of the resin-coated paper is not particularly limited, but it is generally advantageous that the resin layer is extrusion-coated to a thickness of about 5 to 50 μm. In addition, in ordinary resin-coated paper in which both sides of the base paper are coated with resin, the resin surface containing the titanium dioxide pigment has a glossy surface, a matte surface, a silky surface, etc., depending on the application, and The back surface is usually a matte surface, and the front surface or both front and back surfaces can be subjected to activation treatment such as corona discharge treatment and flame treatment as required.

Various silver halide photographic emulsion layers can be provided on the photographic resin-coated paper of the present invention. For example, silver chloride, silver bromide, silver chlorobromide, silver iodobromide, and silver chloroiodobromide emulsion layers can be provided.

Further, a color coupler may be contained in the silver halide photographic emulsion layer to provide a multilayer silver halide photographic constituent layer. As a binder for these silver halide emulsion layers, in addition to ordinary gelatin, hydrophilic polymer substances such as polyvinylpyrrolidone, polyvinyl alcohol, and sulfate ester compounds of polysaccharides can be used.
Further, the silver halide emulsion layer may contain various additives. For example, as sensitizing dyes, cyanine dyes, water-soluble gold compounds as chemical sensitizers such as merocyanine dyes, sulfur compounds, etc., as antifoggants or stabilizers, hydroxy-triazolopyrimidine compounds, mercapto-heterocyclic compounds, etc. As a film agent, formalin, vinyl sulfone compound, aziridine compound, etc. as a coating aid, benzene sulfonate,
As a pollution control agent such as sulfosuccinate ester salt,
Hydroquinone and phenidone as development accelerators such as dialkylhydroquinone compounds, benzotriazole compounds as ultraviolet absorbers such as phenidone, fluorescent whitening agents, sharpness improving dyes, antistatic agents, pH adjusters, and silver halides. Water-soluble iridium compound when dispersed,
A water-soluble rhodium compound or the like can be contained in an appropriate combination.

Further, on the back surface of the photographic resin-coated paper of the present invention, that is, on the surface of the support opposite to the surface on which the photographic constituent layers, most of which are silver halide photographic constituent layers, are coated, curl prevention, A coating layer composed of a hydrophilic colloid layer, which is called a backcoat layer, can be provided for the purpose of antistatic, tackiness prevention, slip prevention and the like. In the back coat layer, a binder or protective colloid,
A hardener, an antistatic agent, a surfactant, a matting agent, a latex and the like can be contained.

The support for photographic printing paper of the present invention can be used as a support for various thermal transfer recording image receiving materials by coating various thermal transfer recording image receiving layers. Further, various ink image-receiving layers may be coated and used as a support for various inkjet recording materials. further,
It is also possible to provide a printed image forming layer on the resin coating layer and use it as a support for lithographic printing.

[0074]

EXAMPLES The present invention will be described in detail below with reference to specific examples. The present invention is not limited to the examples. All percentages below are by weight. Examples 1 to 6 and Comparative Examples 1 to 8 1: 1 mixture of bleached hardwood bleached kraft pulp (LBKP) and bleached softwood sulfite pulp (NBSP) was beaten to a Canadian standard freeness of 300 ml to prepare a pulp slurry. . An alkyl ketene dimer sizing agent having a melting point shown in Table 1, and
Light calcium carbonate having a particle size shown in Table 1 was added as a filler to the dry weight of pulp. Further, as a strength agent, 1.0% by weight of polyacrylamide, 2.0% by weight of cationized starch and 0.5% by weight of polyamide epichlorohydrin were added to the pulp, and diluted with water to 1%. It was made into a slurry. This slurry was made into paper by a Fourdrinier paper machine so as to have a basis weight of 170 g / m ² , and used as a photographic printing paper base.

A photographic photographic paper substrate made from paper has a density of 0.
A polyethylene resin composition, in which 10% by weight of anatase-type titanium was uniformly dispersed, was melted at 320 ° C. to 918 g / cm ³ of low-density polyethylene 100% by weight of resin, and extrusion-coated to a thickness of 30 μm. Extrusion coating was performed using a cooling roll. On the other side, a high density polyethylene resin having a density of 0.962 g / cm ³ was similarly melted at 320 ° C. and extrusion-molded to a thickness of 30 μm.

Subsequently, the resin surface on the surface side containing the titanium dioxide pigment of the support for photographic printing paper thus obtained was subjected to corona discharge treatment, and then a blue-sensitive emulsion layer containing a yellow color coupler, an intermediate layer containing a color turbidity preventing agent, A magenta color coupler is provided with a green-sensitive emulsion layer, an ultraviolet-absorbing layer containing an ultraviolet-absorbing agent, a red-sensitive emulsion layer containing a cyan-coloring coupler, and a protective layer to prepare a color photographic paper with a total gelatin amount of 0.8 g / m ^2. did. Each color-sensitive emulsion layer corresponds to 0.6 g / m ^{2 of} silver nitrate. In addition to gelatin, which contains silver chlorobromide and is necessary for the formation and dispersion of silver halide and film formation, an appropriate amount of antifoggant, sensitizing dye, coating aid, hardener, thickener, filter dye, etc. including.

The evaluation method is as follows. At the time of production, the workability and the defect occurrence rate were evaluated. The operational suitability was evaluated by the number of times the paper machine was stopped for the purpose of operating for 14 consecutive days due to the defects that occurred in the photographic printing paper substrate. ◎: No stop during continuous operation ○: 1 stop during continuous operation △: 2 stops during continuous operation ×: 3 or more stops during continuous operation Defect rate of photographic printing paper substrate The total number of defects / total number of windings × 100 was calculated.

Further, as the evaluation as a support for photographic printing paper, the following physical properties were evaluated by Taber rigidity, PY value, and immersion of developing solution. Taber stiffness The Taber stiffness of the support for photographic printing paper was measured according to JIS P8125. If this value is 17.5 or less, there is a practical problem. For the penetration of the immersion processing solution from the edge, use a sample as photographic printing paper on a color automatic developing machine (SRP-20
The development processing was performed in 14), and the penetration width of the developing solution from the edge was measured. If the penetration width is 0.5 mm or less, there is no practical problem. PY value Film thickness unevenness index PY value is an electronic micrometer that uses a film thickness measuring instrument that measures the thickness variation of the sample as an electric signal through an electronic micrometer by running the sample between two spherical stylus. Sensitivity range is ± 15 μm /
After adjusting the zero point under the condition of ± 3V, 1.5 in the papermaking direction of the sample.
The thickness variation in the papermaking direction of the sample is measured by scanning at a constant speed of m / min, and the obtained measurement signal value is subjected to fast Fourier transform using a Hanning window for a time window using an FFT analyzer. , The power spectrum by the addition average of 128 times of integration is calculated, and it is 0.5 mm to 12.5 mm.
The sum of the power values in the frequency range is the film thickness unevenness index PY
It is defined as a value and is an index showing the formation on the surface of the sheet substrate.

Finally, the surface texture was evaluated by coating an emulsion on a support for photographic printing paper to obtain a color photographic printing paper and evaluating the surface texture of the surface. The sensory evaluation by visual inspection of the surface texture was performed by graded evaluation. ⊚: Very good ○: Good Δ: Normal or slightly bad X: Obviously bad These results are shown in Table 1.

[0080]

[Table 1]

In Examples 1 to 6, color photographic printing papers having good workability and good surface quality were obtained, but Comparative Examples 1 and 4
Then the surface texture does not improve. Further, in Comparative Example 2, the operability was good, but the sizing was very small, the penetration was extremely poor, and there was no practicality. In Comparative Example 7, the surface texture was good, but the penetration was poor, and as a product. Is an impossible level. Further, it is understood that Comparative Examples 3, 5, 6, and 8 have poor operability and poor surface texture, and particularly Comparative Example 8 has poor operability and very poor surface texture.

Examples 7 to 12 Using the photographic printing paper substrate of Examples 1 to 5, a smear layer having the following contents was provided. 100 parts by weight of light calcium carbonate and 0.5 parts by weight of sodium polyacrylate were dispersed in water using a Corres disperser to prepare a pigment slurry having a solid content concentration of 60%. 0.5 parts by weight of tributyl phosphate, 1.0 parts by weight of potassium oleate, 10 parts by weight of an aqueous casein solution (concentration: 10% by weight) dissolved with sodium carbonate, and 18 parts of acrylic acid butadiene methyl methacrylate copolymer latex. (Solid content) was added, and water was further added to prepare a coating liquid having a solid content concentration of 40%. Using this coating liquid, a smear layer shown in Table 2 was provided by a rewet casting method to obtain a highly smooth smear paper. Comparative Examples 9 to 13 Using the photographic printing paper substrate of Comparative Example 1, Examples 7 to 1
Similarly to 2, the smear layer shown in Table 2 was provided, and Comparative Examples 9 and 1
0, 12, and 13 were created. In Comparative Example 11, a smear layer was provided on the photographic printing paper substrate of Comparative Example 3 as in Examples 7-12. Subsequently, a photographic printing paper base body provided with a smear was coated with a polyolefin resin on a photographic printing paper base body obtained in the same manner as in Examples 1 to 6 in both Examples 7 to 12 and Comparative Examples 9 to 13 to prepare an emulsion. Was applied to prepare a photographic printing paper.

Next, the SRa value and the density, which are evaluation methods, were performed as follows, and the results are shown in Table 2. SRa value The surface roughness of the surface on which the emulsion is applied when the paper substrate and the smear layer are provided on the substrate is measured under the following conditions using a three-dimensional surface roughness meter manufactured by Kosaka Laboratory. . S
When the Ra value is not less than 0.15 μm, the glossiness of the printed surface visually when printed as a photographic paper is considerably inferior, and high quality on the product is lost. Cutoff 0.8 mm X measurement length 20.8 mm Y feed pitch 0.5 mm / min Number of measurement 16 lines Density The density of a photographic printing paper substrate was measured according to JIS P8118.

[0084]

[Table 2]

In Examples 7 to 12, color photographic printing papers having good surface texture and image clarity were obtained. In Comparative Example 9, surface quality Taber stiffness was relatively good, but surface texture and image clarity were considerably poor. . Further, in Comparative Examples 10 and 11, although the Taber rigidity is relatively good, the surface texture and the image clarity are deteriorated. Comparative Example 12 is slightly good in surface texture and image clarity, but inferior in rigidity. Comparative Example 13 has very good rigidity,
The surface texture is poor, and the image clarity is significantly reduced.

Examples 13 to 18 and Comparative Examples 12 to 20 The composition of Example 1 was used, and the basis weight was adjusted under the respective papermaking conditions shown in Table 3 such as solid content concentration, upper dehydration rate, absolute dry water content, roll temperature, and linear pressure. 1
A photographic printing paper substrate was made into a paper so as to have a weight of 70 g / m ² . Subsequently, Examples 13 to 18 were applied to a photographic printing paper substrate.
In each of Comparative Examples 12 to 20, a photographic printing paper substrate obtained in the same manner as in Examples 1 to 6 was coated with a polyolefin resin,
The emulsion was applied to prepare a photographic printing paper.

The evaluation method is the same as in Examples 1 to 6
The value and the texture were evaluated. The results are shown in Table 3.

[0088]

[Table 3]

In Examples 13 to 18, photographic printing papers having a good surface texture can be obtained, but as in Comparative Examples 12 to 20, the desired surface texture cannot be obtained except under the respective papermaking conditions.

Examples 19 to 24, Comparative Examples 21 to 24 In the step of cooling and solidifying the molten resin by using the chill roll by the extrusion coating method using the photographic printing paper substrate of Example 1, pressurization of Table 4 The apparatus and the pressurizing condition, ie, the linear pressure and the bending of the cooling roll were used.

As a quality evaluation method, crater-like pores, the appearance and texture of the emulsion surface were evaluated. [Crater-like pores] The crater-like pores are evaluated by observing a 2.0 cm square of the surface of the resin-coated photographic support with a magnifying glass of 10 times and observing a pore with a diameter of 0.4 mm (actually 40 μm) or more. When the crater-like pore grade is 4 or more, the appearance of the photographic printing paper is impaired due to a decrease in gloss. Grade 1: No pores are observed on the surface Grade 2: 1 to 10 are found Grade 3: 11 to 50 are seen 4:51 to 100 are seen Grade 5: 101 or more are seen Emulsion For the appearance and texture of the surface, a sensory evaluation method by visual observation was used. The results are shown in Table 4.

[0092]

[Table 4]

It can be seen that in Examples 19 to 24, the generation of crater-like pores was small and the surface texture was excellent. However, when pressure is applied by the air cylinder of Comparative Example 21, crater-like pores are often generated, and the surface texture is also flickering, which is not practical. Comparative Example 22
However, even if a hydraulic cylinder is used, if the pressure is too small, it will be worse than in Comparative Example 1, and the crater-like pores and surface texture will be significantly reduced. On the contrary, if the pressure is too strong, the surface texture is deteriorated so that the irregularities on the surface of the photographic printing paper substrate are transferred. Furthermore, as in Comparative Example 24, the deflection is 0.1%.
If it exceeds, the crater-like pores will be significantly deteriorated in a specific portion in the width direction of the support for photographic printing paper, which will lose its practical value as photographic printing paper, making it unusable as a product and causing a large loss. . The reason for this is considered to be that the cooling roll and the cooling roll surface and the pressure distribution have non-uniform portions in the width direction.

Examples 25 to 30 and Comparative Examples 25 to 34 In the step of cooling and solidifying the molten resin using the cooling roll by the extrusion coating method using the photographic printing paper substrate of Example 1, the addition of Example 22 is performed. The cooling roll having the surface shape shown in Table 5 was used under the conditions of the pressure device, the linear pressure as the pressurizing condition, and the bending condition of the cooling roll. An emulsion was coated on the obtained support for photographic printing paper in the same manner as in Examples 1 to 6 to prepare a photographic printing paper.

Evaluation Method of Cooling Roll Surface By copying the shape of the cooling roll surface with a replica and observing a three-dimensional scan diagram by a three-dimensional surface roughness meter and an electron micrograph, the flat portion and the concave edge portion are smoothed. The following grade evaluation was performed by visual judgment. ○: The edge part is smooth △: The edge part is slightly angled ×: The edge part is angled and becomes an acute angle Also, the presence or absence of a flat surface by polishing ○: The top of the convex part Has a flat surface x: There is no flat surface on the top of the convex portion. Further, the surface roughness of the obtained cooling roll was a numerical value using a filter, and a cutoff value of 0.8 mm was used in order to remove low frequency components of the roll surface.

The evaluation method was as follows. Quality Evaluation Method The degree of occurrence of peeling lateral unevenness and crater-like pores on the surface of the resin-coated photographic support thus obtained was visually evaluated. Further, the surface of this resin-coated photographic support was subjected to corona treatment, 13 g / m ^{2 of} a color silver halide emulsion was coated, and the distance from the coating start line to the point where the coating amount became uniform was measured. Further, the image clarity of the surface of the developed photographic printing paper was evaluated.

Distance with uniform liquid from the start of emulsion coating When the distance from the emulsion coating start line to the uniform liquid exceeds 50 mm, the tip of the coating is thickly coated, which causes a drying load in the drying zone and causes serious contamination such as paper roll contamination. Cause quality failure.

Horizontal peeling unevenness The peeling horizontal unevenness is evaluated by grade, and if the peeling grade of the resin-coated photographic support is 4 or more, the gloss of the surface of the photographic printing paper is deteriorated and appearance problems are caused. Grade 1: No peeling horizontal unevenness is observed Grade 2: Thin peeling horizontal unevenness is seen Grade 3: Peeling horizontal unevenness is seen, but not visible on the emulsion layer Grade 4: Peeling horizontal unevenness is strong , Grade 5 that can be seen thinly on the emulsion layer: peeling horizontal unevenness is very strong and remains strong on the emulsion layer

Image clarity Image quality is measured by Suga Test Instruments Co., Ltd.
-2DP type was used, and evaluation was performed using an optical comb width of 2.0 mm. When the image clarity C value exceeds 50%, the performance as a photographic printing paper with a mirror surface type and high gloss is lacking,
It causes visual problems. The evaluation results are shown below.

[0100]

[Table 5]

In Examples 25 to 30, the obtained support for photographic printing paper had good peeling lateral unevenness and good surface quality of crater-like pores, and there was no problem. In addition, the emulsion was coated on a support for photographic printing paper, and the distance from the start of emulsion coating to the uniform liquid was good, and the resulting photographic printing paper had a very good surface texture.
Image clarity is also good.

[0102]

EFFECTS OF THE INVENTION The paper substrate to which the filler and the alkyl ketene dimer are added as in the present invention has good workability.
The defect occurrence rate can be significantly reduced. Further, in the case of a photographic printing paper in which both surfaces of these photographic printing paper bases are coated with a polyolefin resin and further an emulsion is applied, the surface texture can be improved. Further, by providing a smear layer on the photographic printing paper base of the present invention to cover both sides with a polyolefin resin, the rigidity of the photographic printing paper support is improved, and in the case of a photographic printing paper coated with emulsion, ,
The surface texture can also be improved. Further, the photographic printing paper substrate of the present invention can be manufactured under the conditions of a two-wire paper machine and thermal calendering, and by applying pressure with a hydraulic cylinder or using a specific cooling roll, photographic printing can be performed. Not only the surface texture as paper, but also good image clarity.As a support for photographic printing paper, the occurrence of crater-like pores and the unevenness of peeling lateral steps are suppressed, and the distance from the start of emulsion coating to uniform liquid application is short. It is good.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A 63-285539 (JP, A) JP-A 2-264939 (JP, A) JP-A 4-107546 (JP, A) JP-A 6- 10943 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03C 1/79

Claims (5)

(57) [Claims] 1. A paper base, and a coating layer formed on both surfaces thereof and containing a polyolefin resin as a main component, wherein the paper base contains natural pulp as a main component, and the paper base has a grain based on a dry weight of the pulp. A filler having a diameter of 3 μm or less is 1.0 to 7.0% by weight, and an alkyl ketene dimer having a melting start temperature of 35 ° C. or higher and a melting point of 50 ° C. or higher is 0.1 to 0.
A photographic printing paper support characterized by containing 5%. 2. Both sides are coated with a polyolefin resin,
At least one surface of the paper base has a smear layer containing an adhesive of 5 to 20 g / m ² , the base paper density of the base paper is 0.90 or more, and the smear layer and the surface of the paper base before smearing SR
The support for photographic printing paper according to claim 1, wherein a is 1.50 μm or less. 3. A method for manufacturing a support for photographic printing paper, wherein at least one surface of a paper substrate is coated with a resin containing a polyolefin resin as a main component, and the paper substrate is a wire forming a web of a Fourdrinier paper machine and a wire thereof. When forming with a two-wire paper machine provided with an endless upper wire so as to sandwich the paper sheet from above, the solid content concentration of the paper sheet immediately before being sandwiched by the upper wire is 1.5 to 2.5% by weight. And the total amount of water dewatered by the upper endless wire and the amount of water dewatered by the lower wire of the Fourdrinier in the part sandwiched between the upper wire and the wire of the lower Fourdrinier. The upper substrate dehydration rate, which is the ratio of the amount of water dehydrated by the upper endless wire, is set to 30 to 50%, and the paper substrate is made into paper so that the obtained web has an absolute dry water content of 2.0 to 7.0%. The temperature of the paper substrate 110 ℃ -250 ℃, linear pressure 40kg
2. The method for producing a photographic printing paper substrate according to claim 1, wherein the photographic printing paper substrate is produced by passing through a nip formed by two metal rolls under a condition of not less than 1 cm / cm and performing thermal calendering treatment. 4. A method for producing a support for photographic printing paper, wherein both sides of a paper substrate are coated with a polyolefin resin by a melt extrusion coating method, when the polyolefin resin on the emulsion coated side is extrusion coated with a hydraulic cylinder. A cooling roll and a press roll are nipped by a linear pressure of 30 to 100 kg / cm via a pressurized backup roll, and the molten polyolefin resin is cooled and solidified in a state where the bending of the cooling roll is 20 μm or less. The method for producing a support for photographic printing paper according to claim 1. 5. The surface of the cooling roll has fine irregularities with a ten-point average roughness Rz of 0.3 to 1.0 μm and an average pitch of 10 to 50 μm on a flat metal surface, and the top of the convex portion is It is flat, and the average inclination angle from the average line of the concave portion to the bottom side is 5 to 7 degrees, the average inclination angle from the average line of the concave portion to the top portion is 2 to 4 degrees, and the edge between the flat portion and the concave portion is The method for producing a support for photographic printing paper according to claim 4, wherein the portion is smooth.