JPH08190170A - Base body for photographic printing paper - Google Patents

Abstract

PURPOSE: To obtain a photographic printing paper having good working property, smoothness and imaging property. CONSTITUTION: This base body for a photographic printing paper is produced by coating at least one surface of a base paper essentially comprising natural pulp with a polyolefin resin compsn. containing a polyolefin resin and titanium dioxide. The density of the base paper after calendering is preferably >=0.98g/cm<3> . The polyolefin resin contains 40-100wt.% high density polyethylene having >=0.945g/cm<3> density. It is preferable that the base paper has <1.65mV inhomogeneity index of film thickness and <=1.3μm center face average roughness, and that the penetration resistance Q of the polyolefin resin compsn. containing titanium dioxide is 3 to 50kg/cm<2> at 200 deg.C and 1000/sec shearing speed. Especially, it is more preferable that the inhomogeneity index of film thickness of the base paper is <=1.30mV, the density of the natural pulp is >=0.70g/cm<3> , the difference AD in the density of the base paper before and after calendering is >=0.05g/cm<3> , the density of the base paper is >=1.04g/cm<3> , and the proportion of high density polyethylene is >=60wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographic printing paper support, and more particularly to a photographic printing paper support which has good operability and is excellent in smoothness and image clarity. Is.

[0002]

2. Description of the Related Art Conventionally, as a support for photographic printing paper,
It is well known that both sides of a base paper are coated with a resin composition mainly composed of a white pigment and a polyolefin resin. Since the support hardly absorbs the developing solution, the washing and drying after the processing can be greatly shortened, and the support has excellent dimensional stability.

However, as compared with the conventional baryta paper which can be mirror-finished after development, the photographic printing paper using the polyolefin resin-coated support needs to have a mirror surface at the stage of the polyolefin resin-coated support, and The white pigment such as titanium dioxide in the resin used for the shielding effect adversely affects the gloss.

The printing paper has "glossy", "silk",
In the case of photographic paper that has a "matte tone" and uses a polyolefin resin-coated support, it is determined by the shape of the surface of the cooling roll that contacts after melt-extruding and coating the polyolefin resin composition on the base paper, but overwhelmingly "Glossy" accounts for the majority and a good mirror surface is required. However, the peelability from the cooling roll is the most "glossy", and peeling is most difficult, and the surface quality such as uneven gloss is likely to be adversely affected.

Various proposals have been made so far for a support for photographic printing paper coated with a polyolefin resin and having good surface smoothness. For example, it is proposed to use a base paper whose center surface average roughness (SRa) measured by a three-dimensional surface roughness meter is below a specific value (Japanese Patent Laid-Open No. 63-291054), and optical surface roughness is below a specific value. Proposal to use base paper of Japanese Patent Application Laid-Open No. Sho 64
No. 80948), both of which can improve the smoothness of the support, but have little effect on the image clarity when used as photographic printing paper after emulsion coating. Also, the density is 0.6
Proposal of adjusting the elastic modulus of a pulp into a specific range by using 0.7 g / cm ³ of pulp (JP-A-64-18145).
However, the effect of improving the smoothness is small, and the effect on the image clarity of the photographic paper after emulsion coating is small.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a photographic printing paper support having good operability, smoothness of printing paper and excellent image clarity.

[0007]

DISCLOSURE OF THE INVENTION As a result of intensive studies to solve these problems, the present inventors have invented the support for photographic printing paper of the present invention.

That is, the photographic printing paper support of the present invention is a photographic printing paper in which a polyolefin-based resin composition containing a polyolefin resin and titanium dioxide is coated on at least one surface of a paper containing natural pulp as a main component. It is a support for paper, the base paper is treated with at least one of a machine calender, a super calender, and a thermal calender, and the density after treatment is 0.98 g / cm ³ or more, and the polyolefin resin is The high density polyethylene (A) having a density of 0.945 g / cm ³ or more is 40 to 100% by weight.

Further, in the support for photographic printing paper of the present invention, preferably, at least one surface of the base paper has a film thickness unevenness index Rp defined below on at least one surface of the base paper in the papermaking direction.
65 mV or less, and a center plane average roughness SRa in the papermaking direction at a cutoff of 0.8 mm or more at a wavelength measured using a stylus type three-dimensional surface roughness meter is 1.3 μm or less. The polyolefin resin composition is 200 ° C.,
Intrusion resistance Q at a shear rate of 1000 / sec is 3 to
It is characterized by being 50 Kg / cm ² . Thickness unevenness index Rp: An optical displacement sensor that irradiates red LED light from above the flat surface, captures the reflected light by the light receiver array, and measures the position of the flat surface. Is located at the center, and the lower surface of the sample just below the beam is supported by a ball point needle, and the sample is fixed on the XY stage while preventing vertical displacement.
The thickness variation in the papermaking direction of the sample was measured by scanning the stage in the X-axis (main scanning axis) direction at a constant speed of 2 mm / sec, and the obtained measurement signal value was measured by the FFT analyzer in the 0-5 Hz frequency range. Perform the frequency analysis of in the Hanning window,
The power spectrum (unit: mV ² ) is calculated by adding and averaging 128 times of integration, and the power spectrum values in the frequency range of 0.175 Hz to ² Hz are summed and multiplied by 2/3 to obtain the power of 1/2. The value obtained by
It is defined as p (unit: mV).

Further, in the support for photographic printing paper of the present invention, the thickness unevenness index Rp on at least one side of the base paper is preferably 1.30 mV or less.

In the photographic printing paper support of the present invention, the density of the natural pulp used for the base paper is higher than 0.70 g / cm ³ , and the density difference ΔD before and after the calendering of the base paper is 0.05.
It is preferably g / cm ³ and the density of the base paper is 1.04 g / cm ³ or more.

Further, the support for photographic printing paper of the present invention comprises a high density polyethylene (A) 6 as a polyolefin resin.
It is preferable to contain more than 0% by weight.

The support for photographic printing paper of the present invention will be described in detail below.

The pulp density of the present invention is measured by the following method. Pulp is JIS JIS by the method of P8210
Beat the freeness to 300 ml according to P8121, and use JI
A handmade paper having a basis weight of 180 g / m ² is prepared according to SP8209, and after conditioning the humidity for 24 hours according to JIS P8111, the weight of the handmade paper and the thickness according to JIS P8118 are measured to calculate the pulp density.

It is preferable that the base paper is treated with at least one of machine calender, super calender and thermal calender so that the density after treatment is 0.98 g / cm ³ or more.
a, a necessary condition for obtaining the film thickness unevenness index. In particular, base paper using pulp with a pulp density of more than 0.7 g / cm ³ has sufficient smoothness by wet press treatment, and good surface properties by treatment with a relatively low machine calender or super calender pressure. As a result, appearance problems such as blacking on the surface and paper paper are less likely to occur. Especially, the density difference ΔD before and after the calendering of the base paper is 0.05.
It is g / cm ³ or more, and the effect is great when the density of the base paper is 1.04 g / cm ³ or more.

When the density of the base paper of the present invention is 0.98 g / cm ³ or more, preferably 1.04 g / cm ³ or more, the SRa and the film thickness unevenness index are good, and when the resin is coated, The smoothness of the surface of the coating resin layer is improved probably because the compression resistance of the base paper between the cooling roll and the pressure roll is increased. Further, the slight decrease in rigidity (waist) due to the high density of the base paper is improved by mainly using the high density polyethylene (A).

The center surface average roughness SRa at a cutoff value of 0.8 mm measured by using a stylus type three-dimensional surface roughness meter referred to in this specification is defined by the following mathematical formula 1. .

[0018]

[Equation 1]

In the above mathematical expression 1, Wx represents the length of the sample surface area in the X-axis direction (paper making direction), and Wy is the Y of the sample surface area.
The length in the axial direction (direction perpendicular to the papermaking direction) is represented by Sa
Represents the area of the sample area.

Specifically, as a stylus type three-dimensional surface roughness meter and a three-dimensional roughness analyzer, SE-produced by Kosaka Laboratory Ltd.
Using 3AK type machine and SPA-11 type machine, cutoff value 0.8mm, Wx = 20mm, Wy = 8mm, therefore Sa =
It can be obtained under the condition of 160 mm ² . Note that 500 points of sampling are performed as the data processing in the X-axis direction, and 17 lines or more are performed as the scanning in the Y-axis direction.

The film thickness unevenness index on at least one side is 1.65.
The base paper having a center plane average roughness SRa of 1.3 μm or less is preferably 2 or more, more preferably 3 or less by the following methods. It has been clarified by the study of the present inventors that the above-mentioned combination can be used.

(1) As the natural pulp used in the present invention, sulfite pulp, preferably hardwood sulfite pulp is suitable. Specifically, JP-A-60-67
30% by weight or more, preferably 50% by weight or more of the hardwood sulfite pulp described or exemplified in Japanese Patent No. 940 is used.

(2) A pressure press is used during the drying of the wet paper. Specifically, for example, the wet paper web is subjected to a multi-stage pressure press as described or exemplified in JP-A-3-29945.

(3) Various water-soluble polymers, hydrophilic colloids or polymer latices are contained in or coated on the base paper. Specifically, various water-soluble polymers or hydrophilic colloids or polymer latices are solid-coated in or on the base paper by size press or tab size press or coating such as blade coating or air knife coating. The amount is preferably 2.2 g / m ² or more, or it is preferably coated.

(4) After making the base paper, at least two or more series of calendar treatments are performed on the base paper using a machine calendar, a super calendar, a thermal calendar or the like. Specifically, for example, the base paper is subjected to machine calendering and / or thermal machine calendering as the first series of calendering, and then further machine calendering is performed as necessary as the second series of calendering. After that, it is preferable to perform the thermal soft calender treatment described or exemplified in JP-A-4-110939.

The support for photographic printing paper of the present invention comprises a base paper coated on at least one side with a specific polyolefin resin containing titanium dioxide and having a density of 0.945 g / cm ^3.
The above high-density polyethylene resin (A) is used in an amount of 40 to 100% by weight, and the intrusion resistance Q of the polyolefin resin composition is preferably in a specific range.

The penetration resistance Q of the present invention is defined as follows. It is calculated from the measurement values measured using the capillary rheometer shown in FIGS. 1 and 2 below. 1 is a cross-sectional view of the outline of a capillary rheometer, FIG.
Shows a cross-sectional view of the capillary portion.

In FIG. 1, the diameter of the cylinder 5 is 10
mm, the diameter D of the capillaries in FIGS. 1 and 2 is 1.5 m
m and length L used three types, 10 mm, 20 mm, and 30 mm. In FIG. 2, the angle θ is 45 degrees.

For the measurement, the thermostat 8 of FIG. 1 is set to a predetermined temperature (200 ° C. in the present invention) and the measurement system temperature is kept constant. Next, the olefin resin layer composition is inserted into the cylinder 5. The load cell 2 and the plunger 3 descend at a constant speed, and the olefin resin layer composition is extruded through the capillary 7. At this time, the load cell 2 detects the sum of the shear stress generated on the capillary tube wall and the intrusion resistance associated with the invasion from the cylinder into the capillary.

FIG. 3 shows a graph in which measured values are plotted. In FIG. 3, stress values measured by capillaries having different lengths are plotted on the Y-axis, and the length / capillary diameter (L /
When the value of D) is plotted on the X axis, the graph of FIG. 3 is obtained.
In FIG. 3, the stress value at the intersection of the Y-axis and the line obtained by linearly approximating the three measurement points represents the intrusion resistance Q. A physical property value n is defined as an intersection with the X axis, and is a value that represents the contribution of the intrusion resistance to the total resistance and is an unnamed number.

Density in polyolefin resin 0.945
If the high density polyethylene (A) of g / cm ³ or more is less than 40% by weight, the smoothness and image clarity of the photographic paper cannot be improved, and if the intrusion resistance Q is less than 3 Kg / cm ² , There is a tendency that the molten resin excessively penetrates into the inside to impair the optical properties such as opacity of titanium dioxide, resulting in poor smoothness of the resin surface. It is preferable that the high-density polyethylene resin (A) is more than 60% by weight. On the contrary, penetration resistance Q is 50 kg / c
If it is larger than m ^{2, the} molten resin will not penetrate into the rough recesses on the surface of the base paper, and the film-forming property between the base paper and the resin layer tends to be poor.

Titanium dioxide is contained in the polyolefin resin layer, but rutile type and anatase type are used, and the average particle size is 0.0 in a directional measurement by an electron microscope.
It is preferably 8 to 0.5 μm. Surface-treated products with alumina or silica and surface-treated with organic substances such as fatty acid metal salts can be preferably used. Generally, 5 to 30% by weight of the polyolefin resin layer is contained as titanium dioxide. It is preferably 10 to 20% by weight. here,
If it is less than 5% by weight, the sharpness of the photographic paper is inferior, and
When it exceeds 30% by weight, the fluidity of the molten polyolefin resin layer becomes poor.

As the resin contained in the polyolefin resin composition of the present invention, various polyethylene, polypropylene, polybutylene, polyethylene terephthalate and the like and copolymers thereof are used in addition to the high density polyethylene (A) having a specific density. It can be used as long as the effect of is not impaired.

Further, the polyolefin resin composition may contain various additives. For example, white pigments such as rutile-type or anatase-type titanium dioxide, zinc oxide, talc, etc., release agents such as fatty acid amides such as stearic acid amide and arachidic acid amide, and fatty acid metals such as zinc stearate and magnesium stearate. salt,
An organosilicon compound such as polyorganosiloxane may be appropriately contained as an antioxidant, a hindered phenol compound or the like may be contained, and a color pigment such as cobalt blue, ultramarine blue or the like and an optical brightener may be appropriately contained.

The polyolefin resin layer in the present invention is
It is manufactured by melt extrusion coating a polyolefin resin composition into a film from a slit die. The melt extrusion temperature at that time is appropriately selected in the range of 200 to 350 ° C. depending on the polyolefin resin composition. As a slit die, T
A die, an L die, a fish-til type die and the like are preferably used. Before the base composition is coated with the resin composition, the base paper is preferably subjected to an activation treatment such as corona discharge or flame treatment. The thickness of the polyolefin resin layer is not particularly limited,
It is generally about 10 to 50 μm.

In the present invention, generally, immediately after the base resin is coated with the polyolefin resin composition by melt extrusion, the surface of the chill roller and the pressure roller having a surface temperature of about 5 to 25 ° C. is heated to 10 to 10 ° C.
The resin layer surface is cooled by adhering the resin surface to the surface of the chill roll by passing it under a pressure of about 50 kg / cm to improve the smoothness of the resin layer surface and the adhesion between the resin layer and the base paper.

Regarding the releasability of the polyolefin resin-coated paper from the cooling roll, the smaller the penetration resistance Q of the resin composition, the better the tendency, but the smoothness of the resin layer surface is poor. However, it has been clarified that both the releasability and the image clarity of the photographic paper are improved by combining with the characteristics of the base paper. That is,
A density difference before and after calendering △ D is 0.05 g / cm ³ or more and a density of 0.95 g / cm ³ or more, preferably less thickness unevenness index specified value, center plane average roughness SRa is more than a specific value By using a base paper and using a specific resin composition having an intrusion resistance Q of a specific range, it is possible to obtain a photographic paper having a good releasability and a good image clarity.

In the photographic printing paper of the present invention, on the polyolefin resin coating layer for the purpose of improving sharpness,
An undercoat layer containing a hydrophilic colloid binder such as gelatin, a latex such as styrene-butadiene, a methyl methacrylate-butadiene copolymer, and a white pigment such as titanium dioxide may be applied. The coating amount is preferably 0.5 g / m ² or more, more preferably 2 g / m ² or more.

Between the polyolefin resin layer or the undercoat layer and the silver halide emulsion layer, an intermediate layer is continuously provided with the emulsion layer by a reduced pressure slide bead system or a slide hopper system for the purpose of preventing irradiation and fog. However, the thickness of the coating layer of the intermediate layer is preferably 4 to 5 μm or less, and when the coating layer of the intermediate layer is thicker than 4 to 5 μm, the sharpness becomes poor.

A slide bead method and a reduced pressure slide bead method are used for coating the silver halide emulsion.

The slide bead method is also called a slide hopper method or an E-bar method, and has a discharge slit of the coating liquid on the upper edge of the slanting slide surface, and the slide surface is inclined while forming a coating layer once. Then, the coating is applied onto the surface of the support while being stacked on the lower coating layer one after another to form a predetermined laminate and forming small beads collectively. The method is disclosed in JP-A-52-115214.
The coating method is described in JP-A-54-1350, and various technical disclosures regarding formation of a good photographic layer are made in JP-A-3-269528.

The pressure-reducing slide bead system is a system in which a pressure-reducing chamber is provided immediately before coating a bead on the surface of a support by a slide bead system to reduce the pressure to improve the coating property. US Pat. No. 2,681,294 , Ibid 2,761,419
No. 2,761,791 and the like, and a method for uniformly stabilizing the coating is described in U.S. Pat. No. 3,220,877, JP-A-62-121451, It is disclosed in Japanese Patent Laid-Open No. 1-258772.

As the base paper used in the present invention, in addition to the paper using the natural pulp having the pulp density of the present invention, a mixed paper using natural pulp and synthetic fiber is used.

In the base paper, a sizing agent, a wet paper strength enhancer, a filler, a pH adjusting agent, a coloring agent, a coloring dye, a fluorescent agent, etc., which are used in ordinary papermaking, a starch type, a polyvinyl alcohol type, or a surface size, Properly contains water-soluble polymers such as gelatin, inorganic or organic antistatic agents such as sodium chloride, potassium chloride, sodium polystyrene sulfonate, pigments such as kaolin, clay, calcium carbonate, coloring pigments, dyes, fluorescent agents, etc. can do.

The support of the photographic printing paper in the present invention includes
Various back coat layers can be provided for the purpose of preventing electrification and curling. The material of the back coat layer is colloidal silica, colloidal synthetic hectorite,
Sodium chloride, polystyrene sulfonate, hydrophilic binder, latex polymer, pigment, surfactant and the like can be used.

In the photographic printing paper of the present invention, various photographic constituent layers are coated to provide color photographic printing paper, black and white photographic printing paper,
It can be used for various purposes such as phototypesetting photographic paper and copy photographic paper. For example, an emulsion layer of silver chloride, silver bromide, silver chlorobromide, silver iodobromide or the like can be provided. It is also possible to provide a color coupler in the silver halide emulsion layer to provide a multilayer silver halide color photographic constituent layer. As the binder, in addition to ordinary gelatin, polyvinylpyrrolidone, polyvinyl alcohol and the like can be used. Photographic layers include sensitizing dyes, chemical sensitizers, antifoggants, hardeners,
It may contain a fluorescent whitening agent, an antistatic agent, a pH adjusting agent and the like.

The photographic printing paper of the present invention is subjected to various treatments such as exposure, development, stopping, fixing, bleaching, and stabilizing as described in "Photosensitive Materials and Handling Methods" (Kyoritsu Shuppan, Goro Miyamoto). It is applied to form a photographic image.

[0048]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.
The parts and% in the examples mean parts by weight and% by weight, respectively.

Example 1 A mixed pulp composed of 70% hardwood bleached sulfite pulp and 30% hardwood bleached kraft pulp (density 0.74 g
/ Cm ³ ) is beaten according to JIS P8121 to a Canadian freeness of 300 ml, and then 100 parts of pulp, 3 parts of cationic starch, 0.2 part of anionized polyacrylamide, and an emulsion of alkyl ketene dimer. As a resin component, 0.4 parts of a polyamide epichlorohydrin resin, and an appropriate amount of a fluorescent whitening agent, a blue dye and a red dye were added to prepare a stock slurry. Using it 2
A quadruple paper machine running at 00 m / min is used to form a web while giving an appropriate turbulence, and a wet part 1
After performing 3 steps of wet pressing in the range of 5 to 100 kg / cm, it is treated with a smoothing roll, and then dried in a drying part.
Two-stage pressure pressing was performed at a linear pressure of 0 to 70 kg / cm, and then dried. Then, in the middle of drying, a size press liquid consisting of 4 parts of carboxy-modified polyvinyl alcohol, 0.05 part of optical brightening agent, 0.002 part of blue dye, 4 parts of sodium chloride and 92 parts of water was pressed at 25 g / m ² size. Then, the base paper finally obtained was dried so that the water content in the final dry paper was 8%. After that, machine calendering, temperature 150 ℃
The difference in density ΔD of the base paper before and after the treatment was 0.09 g / cm ³ , the basis weight was 180 g / m ² , and the density was 1.05.
g / cm ³ , surface SRa of 1.08 μm, transmembrane pressure index R
A base paper with a p of 1.10 mV was obtained.

Then, after corona treatment on the back surface of the base paper, the ratio of high density polyethylene (density: 0.962 g / cm ³ ) to low density polyethylene (density: 0.926 g / cm ³ ) was 50:
The mixture of 50 was melt-extrusion coated to a thickness of 30 μm at a speed of 200 m / min, corona-treated on the surface of the base paper, and a high density polyethylene (density: 0.962 g / cm ³ ) and a low density were obtained as a polyolefin resin composition. A mixture of polyethylene (density: 0.926 g / cm ³ ) in a ratio of 80:20 was treated with aluminized anatase titanium dioxide to give a composition of 15
The polyolefin resin composition mixed so as to have a weight ratio of 30 μm at a speed of 200 m / min and a melting temperature of 31 μm.
Melt extrusion coating at 0 ° C, linear pressure with pressure roll 30
After cooling roll treatment with Kg / cm and cooling water temperature of 15 ° C,
A polyolefin resin coating layer was provided on the surface of the base paper to obtain the support for photographic printing paper of the present invention. The penetration resistance of the polyolefin resin composition was 16 kg / cm ² .

An emulsion layer and a protective layer were simultaneously provided on the polyolefin resin coating layer on the surface of the base paper by a reduced pressure slide bead system to prepare a black and white photographic printing paper.

The emulsion layer comprises hexachloroiridium (II
I) ArBr / AgCl / AgI = 95 / 4.5 / 0.I manufactured by dispersing and producing 19.2 g of silver halide grains as silver nitrate in the presence of 1.2 × 10 ⁻⁵ g of potassium acid.
It has a silver halide photographic emulsion composition of 5 (mol%) in 14.4 g of gelatin, and is sensitized by sulfur sensitization and gold sensitization to the optimum sensitivity with an average grain size of 0.6 μm. Containing a neutral silver halide photographic emulsion consisting of a [0, 0, 1] surface, and further containing gelatin necessary for film formation, an appropriate amount of a stabilizer, a sensitizing dye, a coating aid, a hardener, Contains optical brighteners, thickeners, filter dyes, etc., 2.2g / m ^{2 with} silver nitrate,
With gelatin, apply a coating amount equivalent to 4.4 g / m ^2, and adjust the degree of vacuum in the vacuum chamber with the vacuum slide bead coating device together with the protective layer.
Multilayer coating was performed at 60 mmH ₂ O and a coating speed of 100 m / min, and the coating was dried. The protective layer contains a coating aid and a hardening agent in addition to gelatin equivalent to ² g / m ² .

Example 2 In Example 1, 100 high density polyethylene resin having a density of 0.970 g / cm ³ was used as the polyolefin resin on the surface of the base paper.
% A black-and-white photographic printing paper was obtained in the same manner as in Example 1 except that the same was used. The penetration resistance of the polyolefin resin composition was ² Kg / cm ² .

[0054] Example 3 Example 1 density of the polyolefin resin of the base paper surface in the high-density polyethylene resin and a density of 0.945 g / cm ³ low-density polyethylene 0.920 g / cm ^3, density of 0.9
A black and white photographic printing paper was obtained in the same manner as in Example 1 except that the ratio of polypropylene of 00 g / cm ³ was changed to 50:30:20. The penetration resistance of the polyolefin resin composition is
It was 54 Kg / cm ² .

Example 4 In the same manner as in Example 1, except that only hardwood bleached kraft pulp (density 0.66 g / cm ³ ) was used as the pulp used for the base paper, the density difference ΔD between the base paper before and after the calendering treatment was performed in the same manner. Is 0.05 g / cm ³ , basis weight 180 g / m ² , density 1.00 g / c
m ³ , SRa 1.30 μm, film thickness unevenness index Rp 1.7
A 5 mV base paper was obtained, and a black and white photographic printing paper was obtained in the same manner.

Example 5 A mixed pulp (density 0.68 g / c) composed of 30% of hardwood bleached sulfite pulp and 70% of hardwood kraft pulp was used as the mixing ratio of the pulp used for producing the base paper of Example 1.
m ³ ), except that the density difference ΔD of the base paper before and after calendering was 0.100 g / cm ³ , and the basis weight was 180 g / m ² ,
A base paper having a density of 1.07 g / cm ³ , SRa of 1.15 μm, and a transmembrane pressure index Rp of 1.23 mV was obtained. In the same manner as in Example 1, a support for photographic printing paper of the present invention was obtained. Black and white photographic printing paper was obtained in the same manner as in Example 1.

Example 6 In addition to the high-density polyethylene and the low-density polyethylene used as the surface polyolefin resin in Example 1, the density was 0.
Using polypropylene 900 g / cm ^3, their ratio is 5
A support for photographic printing paper of the present invention was obtained in the same manner as in Example 1 except that 0:35:15 was used, and a black and white photographic printing paper was obtained in the same manner as in Example 1. The penetration resistance of the polyolefin resin composition was 45 kg / cm ² .

Example 7 The density difference ΔD of the base paper before and after calendering was 0.06 g / cm ³ , the basis weight was 180 g / m ² , and the density was 1.02 g / in the same manner as in Example 2 except for the calendering conditions. A base paper having a cm ³ surface, an SRa of 1.26 μm on the surface, and a transmembrane pressure index of 1.58 mV was obtained. Others were made in the same manner as in Example 1 to obtain a black-and-white photographic printing paper.

Example 8 The composition of the polyolefin resin layer on the surface of the base paper of Example 1 was the same as that of Example 1 except that the ratio of high density polyethylene to low density polyethylene used in Example 1 was changed to 45:55. A support for photographic printing paper of the invention was obtained, and a black and white photographic printing paper was obtained in the same manner as in Example 1. The penetration resistance of the polyolefin resin composition was 30 kg / cm ² .

Example 9 Pulp used in producing the base paper of Example 1 was 100% hardwood bleached sulfite pulp (density 0.76 g / cm ³ ).
In was replaced in the same manner as the density difference of the base paper before and after calendering △ D is 0.100 g / cm ^3, a basis weight of 180 g / m ^2, density of 1.05g / cm ^3, SRa is 1.00 .mu.m, film A base paper having a pressure unevenness index Rp of 1.05 mV was obtained, a support for photographic printing paper of the present invention was obtained in the same manner as in Example 1, and a black and white photographic printing paper was obtained in the same manner as in Example 1.

Comparative Example 1 In Example 1, the base paper was calendered only by a machine calender, and the density difference ΔD of the base paper before and after the treatment was 0.04.
g / cm ³ , basis weight 180 g / m ² , density 0.96 g / cm ³ , SRa
Was 1.38 μm and the transmembrane pressure index Rp was 1.65 mV, and a black-and-white photographic printing paper was obtained in the same manner as in Example 1.

Comparative Example 2 The ratio of the high density polyethylene used as the polyolefin resin on the surface of the base paper in Example 1 to the low density polyethylene was 3
A black-and-white photographic printing paper was obtained in the same manner as in Example 1 except that the ratio was set to 5:65. The penetration resistance of the polyolefin resin composition was 43 Kg / cm ² .

Comparative Example 3 Density difference Δ of the base paper before and after calendering was similarly performed except that only hardwood bleached kraft pulp (density 0.63 g / cm ³ ) was used as the pulp used in the base paper in Example 1. D is 0.06 g / cm ³ , basis weight 180 g / m ² , density 0.96 g / c
m ³ , SRa 1.30 μm, film thickness unevenness index Rp 1.7
A 0 mV base paper was obtained, and a black and white photographic paper was obtained in the same manner as in Example 1.

The black and white photographic printing papers obtained in Examples 1 to 10 and Comparative Examples 1 to 3 were evaluated by the following methods. Table 1
Table 2 shows the results of the pulp content and base paper characteristics, and Table 2 shows the evaluation results of the cooling roll releasability and the photographic paper image clarity. In Table 1, PE is an abbreviation for polyethylene and PP is an abbreviation for polypropylene.

[Cooling roll releasability] The releasability from the chill roll when the base paper used in Examples and Comparative Examples was coated with the polyolefin resin composition was evaluated. ⊚: Peeling is smooth and there is almost no peeling noise. ◯: Peeling is smooth and peeling sound is slightly present. Δ: Some sticking at the time of peeling, peeling noise, practical lower limit. X: There is sticking at the time of peeling, the peeling noise is loud, and the surface quality is apparent and there is lateral unevenness.

[Mapping property] The measuring method is JIS H8686.
The image clarity is determined as the image clarity from the waveform of the amount of light obtained through the optical comb defined by. Measured value when the slit width is 2 mm.

[Smoothness] SRa by a three-dimensional stylus roughness meter
(Μm, cutoff of 0.8 mm or more) is determined. The larger the number, the coarser it is.

[0068]

[Table 1]

[0069]

[Table 2]

As is apparent from Table 2 above, the photographic printing papers of Examples 1 to 9 of the present invention were excellent in various characteristics.
On the other hand, the photographic printing papers of Comparative Examples 1 to 3 have roll peelability,
It was inferior in image clarity. In particular, the photographic printing paper of Comparative Example 3 had poor image clarity.

[0071]

The photographic printing paper using the photographic printing paper support of the present invention is excellent in operability during production of the support, smoothness of the photographic printing paper, and image clarity.

[Brief description of drawings]

FIG. 1 is a sectional view of an outline of a capillary rheometer.

FIG. 2 is a cross-sectional view of a capillary portion.

FIG. 3 is a graph in which measured values are plotted.

[Explanation of symbols]

 1 Falling Beam 2 Load Cell 3 Plunger 4 Cylinder Block 5 Cylinder 6 Capillary Block 7 Capillary 8 Constant Temperature Chamber

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location D21H 19/20

Claims (5)

[Claims] 1. A support for photographic printing paper, comprising a base paper comprising natural pulp as a main component, and at least one surface of which is coated with a polyolefin resin composition containing a polyolefin resin and titanium dioxide. It has been processed with at least one of a machine calendar, a super calendar, and a heat calendar, and the density after processing is 0.9.
And at 8 g / cm ³ or more, the polyolefin resin has a density 0.945 g / cm ³ or more high-density polyethylene (A) is 4
A support for photographic printing paper, characterized in that it is 0 to 100% by weight. 2. The base paper has a thickness unevenness index Rp defined below of 1.65 m on at least one side in the paper making direction of the base paper.
V or less, and a center plane average roughness SRa in the papermaking direction at a cutoff of 0.8 mm or more at a wavelength measured using a stylus type three-dimensional surface roughness meter is 1.3 μm or less, and a polyolefin resin composition The material is 200 ° C. and the shear rate is 1000 /
The support for photographic printing paper according to claim 1, wherein the penetration resistance Q in sec is 3 to 50 kg / cm ² . Thickness unevenness index Rp: An optical displacement sensor that irradiates red LED light from above the flat surface, captures reflected light with a photodetector array, and measures the position of the flat surface.
The level meter needle is located at the center, and the lower surface of the sample just below the beam is supported by the ball point needle, and the sample is fixed to the XY stage while preventing vertical displacement. The thickness variation in the papermaking direction of the sample is measured by scanning at a constant speed of 2 mm / sec in the (scanning axis) direction, and the measured signal value obtained is 0 by the FFT analyzer.
The power spectrum (unit: mV ² ) is calculated by performing a frequency analysis in the frequency range of -5 Hz in the Hanning window and performing the addition and averaging of the integration of 128 times, and 0.175 Hz to ² Hz.
The value obtained by summing the power spectrum values in the frequency range of ∘ and multiplying the value by 2/3 to the power of 1/2 is defined as the film thickness unevenness index Rp (unit: mV). 3. The support for photographic printing paper according to claim 2, wherein the base paper has a thickness unevenness index Rp of at least one surface of 1.30 mV or less. 4. The base paper has a density of natural pulp of 0.70 g.
/ Cm ³ , the density difference ΔD of the base paper before and after the calendar treatment is 0.05 g / cm ³ or more, and the density of the base paper is 1.0.
4. The photographic paper support according to claim 1, wherein the support is 4 g / cm ³ or more. 5. The photographic printing paper support according to claim 1, wherein the polyolefin resin is more than 60% by weight of the high-density polyethylene resin (A).