JPH07261325A - Resin-coated photographic substrate and its production - Google Patents

Abstract

PURPOSE:To provide a photographic printing paper capable of maintaining high gloss after an emulsion is applied by preventing the release and lateral unevenness of the surface of a resin-coated photographic substrate and formation of crater-shaped micropores at a high-speed extrusion coating and marking of 150m/min or higher. CONSTITUTION:The ten-point average roughness of the surface of the resin- coated photographic substrate on the emulsion layer at <=0.08mm wavelength is controlled to 0.3-0.7mum the average pitch to 5-40mum and the relative load length of 10-50% when the cutting depth/maximum height on a relative load curve is 30%. Consequently, the deposition of the resinous component on a cooling roll is reduced, the release and lateral unevenness on the substrate surface and the generation of crater-shaped micropores are prevented, the high gloss of the printing paper is maintained after the emulsion is applied, and a good surface for the printing paper is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention uses a specific cooling roll and heats a thermoplastic resin such as polyolefin (hereinafter simply referred to as resin) with an extruder at a speed of 150 m / min or more on a substrate such as paper. The present invention relates to a resin-coated photographic support which is melted, coated and surface-molded, and a method for producing the same.

[0002]

2. Description of the Related Art A photographic support coated with a resin is heated and melted with an extruder and extruded in a film form between a base material such as paper and a cooling roll, and the resin melted with a nip roll or the like is used as a base material. Coated and manufactured. The cooling roll is used to form the surface shape of the resin coating layer, and the surface of the resin-coated photographic support is shaped into a mirror surface or a rough surface depending on the shape of the cooling roll surface. Etc. can be formed.

When a cooling roll having a mirror surface (highly smooth surface) is used, the adhesive force between the molten resin and the surface of the cooling roll is greater than that of the cooling roll having a rough surface, and the cooling roll is not sufficiently cooled. Fine ridges called peeling lateral unevenness are striped on the surface of the resin-coated photographic support having a certain periodicity in a direction perpendicular to the traveling direction. The occurrence of this peeling horizontal unevenness prevents the molten resin from being sufficiently cooled as the production speed increases, and the adhesive force between the cooling roll and the molten resin increases, which tends to occur and hinders the improvement of the production speed. Is the cause.

Further, the continuous operation causes low-molecular components of the resin to be deposited on the surface of the cooling roll, and the deposit causes defective peeling to impair the appearance of the surface. The gloss of the film changes and the value of the product is impaired, and even if uniform extrusion coating is performed at a constant speed, a phenomenon occurs in which the resin layer of the resin-coated photographic support peels from the cooling roll in a rhythmic manner. Becomes

Further, in carrying out the high-speed resin coating patterning, the generation of crater-like pores on the surface of the resin coating becomes remarkable, and the generation frequency increases exponentially with the processing speed. In particular, at high speed processing of 150 m / min or more, crater-like pores on the surface of the resin coating become conspicuous, resulting in a level that cannot be practically used.

The crater-like pores generated on the resin-coated surface are between the molten resin coated on the base material and the cooling roll when the base material and the molten resin are pressure-bonded during high-speed extrusion coating. Air entrapment occurs due to the entrainment of air, and crater-like pores are generated on the resin-coated surface.

As a method for preventing the crater-like pores, there is a method of increasing the pressing pressure of the nip roll and decreasing the entrainment of air. However, when the pressing pressure of the nip roll is increased, the heating and melting of the coating is performed. There is a problem that the surface of the resin layer is affected by the unevenness of the base material, and a smooth surface as a photographic support cannot be obtained. Furthermore, depressurization of the atmosphere around the crimped portion, wind shielding, etc. can be mentioned, but it is not a sufficient method.

When a resin such as a paper is coated on a base material such as paper using a cooling roll having a rough surface having various irregularities such as a matte surface, a silky surface, and a textured surface, the speed is considerably high. Since crater-like pores generated on the resin-coated surface hardly occur even when the resin is coated, a method of reducing the crater-like pores by roughening the surface shape of the cooling roll was also studied. The reason why the surface shape of the cooling roll is roughened is that when the base material and the molten resin during high-speed extrusion coating die-molding are pressure-bonded, the air between the molten resin coated on the base material and the cooling roll is increased. However, if there are irregularities in the shape of the cooling roll surface that are relatively larger than this air pool, no crater-like pores will be generated, or if the crater-like pores have a rougher surface shape. This is because it is too large to be confirmed.

However, in the case of a photographic printing paper in which an emulsion is coated on a photographic support having a base material coated with a molten resin by using a cooling roll having a rough surface shape, whether the specular gloss is matte or not. Or, it has a defect that only a print surface with poor gloss can be obtained, and lacks the performance as a mirror-type high-gloss photographic printing paper, and has a fatal defect in terms of quality, so it is not a product. On the contrary, when the substrate is coated with the molten resin by using a cooling roll having fine surface irregularities, the peeling lateral unevenness and the crater-like pores increase as described above, and the photographic support Even in the case of a photographic printing paper coated with emulsion on the surface, defects on the photographic support remain on the emulsion layer, peeling horizontal unevenness shows horizontal stripes, and crater-like pores cause printing. The glossy surface is flickered, appears to be scattered, and has a drawback that it cannot be put to practical use.

As described above, in order to improve productivity, it is necessary to obtain an optimum shape because the roughness of the unevenness on the surface of the cooling roll has contradictory problems. To make matters more complicated, it was found that the glossiness of visual images is different even when the print surface of a photographic printing paper has a normal gloss meter, even if the print surface has the same value. It is becoming clear that evaluation alone is not enough.

[0011]

As a method for preventing peeling lateral unevenness, a separating agent is added to the resin to reduce the adhesion of the resin deposit to the surface of the cooling roll and to extrude the resin deposit. There has been proposed a method of uniformly peeling the resin film thus formed from the cooling roll.
For example, in JP-A-63-30841, a method for providing a resin coating layer containing 40 ppm to 1% of polyalkylene glycol, and in JP-A-64-9444, there is contained 40 to 1500 ppm of a fluorine-containing polymer. There has been proposed a method of improving peelability and stains on a cooling roll by providing a resin layer. However, in these methods, when the amount of the separating agent added is excessive,
The appearance of the product is impaired due to poor resin kneading, increased smoke generation, and accompanying stains on the cooling roll and spot-like stains on the resin layer surface due to the adherence of oil smoke. In addition, the adhesive force between the base material such as paper and the resin decreases, and the value of the product is impaired, which is not a sufficient method.

Further, in JP-A-3-200140, attention is paid to the apparatus itself around the extruder, and a resin coating layer which is cooled and solidified by a cooling roll and bound to a sheet-shaped substrate is attached to the cooling roll by 5 mm. A method of improving by peeling from a cooling roll via a peeling roll arranged at the following intervals is also proposed. However, this method may be effective in the range of 100 m / min as described in the publication, but when the resin is applied at a high speed of 150 m / min or more, the interval between the cooling roll and the peeling roll is No effect was observed even if it was arranged at 5 mm or less.

Furthermore, as an effective measure against unevenness of peeling lateral steps, there is a method in which a cooling roll having fine irregularities is used and the surface of the resin-coated photographic support is imprinted with the fine irregularities, which is disclosed in JP-B-62- Although proposed in Japanese Patent Publication No. 19732 and described as an upper limit coating speed of 100 m / min or more, during high speed processing of 150 m / min or more, the amount of fouling component of the resin deposited on the cooling roll per unit time is accelerated. As a result, the adhesive force between the cooling roll and the molten resin is increased, and as a result, peeling lateral unevenness cannot be prevented.

Further, the publication does not describe the crater-like pores, and the crater-like pores cannot be prevented during high-speed extrusion coating molding at 150 m / min or more using the described cooling roll. . Further, although the surface roughness and pitch of the cooling roll are regulated, the shape of the unevenness does not consider the uniformity. If the surface shape is non-uniform, the surface irregularity of the resin-coated photographic support on the side to which the shape is transferred will also be non-uniform, resulting in a visual gloss on the surface of the photographic paper coated with the photographic emulsion. May be reduced and the issue is still unresolved.

Next, as a measure against crater-like pores, Japanese Patent Laid-Open No. 63-246227 discloses a thermoplastic resin film in which a space surrounded by a thermoplastic resin cooling member and a thermoplastic resin film before cooling is used. A method of preventing crater-like pores by maintaining an atmosphere of a gas having good permeability has also been proposed. However, in this method, by using a gas having good permeability to the thermoplastic resin membrane such as carbon dioxide, a huge investment is required in terms of equipment and safety, and high-speed extrusion coating molding is required. The behavior of gas induces instability of the film and cannot stably prevent crater-like pores.

Further, in JP-A-59-198451, divides the polyolefin 2-layer, sequentially coating, the thickness of the polyolefin layer (t _a) and the thickness of the polyolefin layer of the base paper side (t _b) Has been proposed to prevent crater-like pores by adjusting the ratio to 0.35 to 4.0. However, in this method, by sequentially coating, the device itself becomes large, and
Equipment costs increase. In addition, by coating the resin twice or more, the process loss also tends to increase.
Not necessarily a useful method.

Further, a method of improving crater-like pores from the surface shape of the raw paper surface before coating with a resin has been investigated. For example, in Japanese Patent Laid-Open No. 4-81835, the internal bond strength is set to 1.2 to 1.8 kg · cm, and
A method of preventing crater-like pores by coating a base paper calendered between a metal roll and a synthetic resin roll with polyolefin, and JP-A-4-81836 discloses a base paper with a metal roll-synthetic resin roll. A method of preventing crater-like pores by coating a polyolefin immediately after the calender treatment is also proposed. Although these methods certainly have the effect of preventing crater-like pores, extrusion coating die-molding at 150 m / min or more weakens the effect, and is not a fundamental measure.

Regarding the evaluation of the appearance characteristics as a photographic printing paper in which an emulsion is coated on a resin-coated photographic support, the evaluation method based on color and gloss has already been established as a standard, and the measuring method is generalized. You are using However, in recent years, there has been increasing criticism that these methods can be theoretically affirmed, but are unsatisfactory in practical use. In particular, when two photographic printing papers having the same specular gloss are compared, if the object images appearing differently on the emulsion print surface look different, the visual sense of glossiness is that of a photographic printing paper with a clearer image. However, a high glossiness may be perceived. For example, in products such as home electric appliances and car bodies where importance is attached to the aesthetics of the surface, it is the same that the evaluation that correlates with the visual sense cannot be performed only by measuring the specular gloss. Therefore, it has become necessary to measure the image clarity of the emulsion print surface of photographic printing paper.

From the above, 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 extrusion coating of the resin-coated photographic support. However, increasing the roughness lowers the image clarity of the emulsion surface, and has the contradictory problem. Therefore, it is necessary to obtain an optimum shape.

Therefore, the first object of the present invention is to prevent peeling lateral unevenness on the surface of a resin-coated photographic support even at an extrusion coating molding speed of 150 m / min, and further, in high-speed continuous operation. It is to prevent the resin component from accumulating on the cooling roll with the passage of time.
The second purpose is to prevent crater-like pores on the surface of the resin-coated photographic support. further,
A third object is to achieve a resin-coated photographic support that maintains a high glossy feeling on a photographic printing paper after emulsion coating, and a method for producing the same.

[0021]

The present invention relates to a resin-coated photographic support obtained by extrusion-molding a molten polyolefin resin onto a paper or synthetic paper substrate at a speed of 150 m / min or more. , The resin-coated surface on the side on which the emulsion layer is provided has a ten-point average roughness (hereinafter abbreviated as Rz) of 0.3 to 0.
7 μm, the average pitch is 5 to 40 μm, and the cutting depth in the relative load curve (hereinafter abbreviated as CV) /
A resin-coated photographic support having a surface roughness of 10 to 50% in relative load length (hereinafter abbreviated as tp) when the maximum height (hereinafter abbreviated as Rmax) is 30%.

The present invention also provides a method for producing a resin-coated photographic support in which a molten polyolefin resin is extrusion coated onto a paper or synthetic paper substrate, wherein the extrusion coating molding speed is 150 m / min or more, and the emulsion layer is The resin-coated surface on the side on which is provided has a surface wavelength of 0.8 mm or less, Rz of 0.8 to 1.2 μm, and an average pitch of 5 to 30.
A resin-coated photographic support which is subjected to patterning while being cooled by using a cooling roll having a surface roughness of 50 to 90% when the CV / Rmax in the relative load curve is 70% and the CV / Rmax is 70%. Is a manufacturing method.

The present invention will be described in detail below. First, the roughness parameter representing the surface shape used in the present invention will be described. The Rz used in the present invention is calculated by the equation 1, and can be analyzed by, for example, a surface roughness analyzer Surfcom E-RM-S27A type manufactured by Tokyo Seimitsu. R in the present invention
z is the average value of the elevations from the highest to the fifth summit measured in the direction of longitudinal magnification from a straight line that does not cross the cross-section curve and is parallel to the average line in the part extracted by the reference length from the cross-section curve. The value of the difference from the average value of the height of the valley bottom from the deepest to the fifth is expressed in micrometers (μm). JIS B0601-1982 (Japanese Industrial Standards)
Stipulated in.

[0024]

[Formula 1] Rz = {(R1 + R3 + R5 + R7 + R9)-(R2
+ R4 + R6 + R8 + R10)} / 5

R1, R3, R5, R7, and R9 are the highest to fifth peaks of the extracted portion corresponding to the reference length, and R
2, R4, R6, R8, and R10 are the deepest to fifth valley bottoms of the extracted portion corresponding to the reference length.

The average pitch in the present invention means a distance from a point from a mountain to a valley to a crossing point from the next mountain to a valley across the average line in a portion obtained by extracting a reference length from a sectional curve. If Smi is N and the total number of intervals is N, the average pitch can be calculated by the following equation 2, and ISO 4
287/1 (international standard).

[0027]

## EQU00002 ## Average pitch = (1 / N) .SIGMA.Smi (.mu.m)

The term tp in the present invention means that a certain length is extracted from the cross-section curve and parallel to the average line of this reference length section (the distance from the highest peak of the reference length section to this level is called CV). When the reference length section is cut by the straight line of, the ratio of the sum of the lengths (L) of the cut line segments to the reference length is called tp at that level (CV), IS
O 4287/1 (international standard). In the present invention, the cutting depth CV / Rmax
The relative load length tp in (%) was used as an index of the uniformity of the surface shape of the unevenness in the height direction.

[0029]

[Equation 3] tp = (L1 + L2 + Ln-1 + Ln) / reference length × 100 (%)

Rmax in the present invention means two straight lines which are parallel to the average line of the portion of the reference curve extracted from the sectional curve and have the highest peak height, and two straight lines which are parallel to the average line and have the lowest valley depth. The distance is measured in the direction of the longitudinal magnification of the sectional curve, and this value is expressed in micrometers (μm). It is defined in JIS B0601-1982 (Japanese Industrial Standards).

The image clarity corresponding to the visual glossiness in the present invention will be described in detail. Image clarity is an important index that determines the aesthetic factor of automobile body painting, as an index of how sharply an object is projected on the surface of the coating film and without distortion. It is a characteristic that has been developed in recent years. The image clarity is defined by JIS H 8686, and an optical device is used to determine the image clarity as the image clarity from the waveform of the light quantity obtained through the optical comb. The optical comb has a dark / light ratio of 1: 1 and its width is 0.125, 0.5, 1.0.
And various types of 2.0 mm. In the measurement, the optical comb is moved, the maximum waveform (M) and the minimum waveform (m) on the recording paper are read, and the image definition is obtained by the following formula.

[0032]

## EQU00004 ## C = (M-m) / (M + m) .times.100 where C is the image clarity (%), M is the highest waveform, and m is the lowest waveform. The image clarity C indicates that the larger the value, the better the image clarity, and the smaller the value, the “blur” or the “distortion”. It can be seen that if the “blur” or “distortion” of this image is small, even if the gloss values on the gloss meter are the same, the glossiness by visual observation is improved.

Next, the resin-coated photographic support of the present invention will be described in detail. As a result of investigations using cooling rolls having various surface irregularities, the present inventors have found that a factor that deteriorates the image clarity of the emulsion surface is minute waviness generated on the emulsion surface. It was clarified that this waviness was generated in the uneven portion of the surface of the resin-coated photographic support that was modeled by the unevenness of the cooling roll surface.
Therefore, the pitch of the uneven portion of the surface shape of the resin coated photographic support, which is manufactured by using the cooling roll in which the height of the uneven portion is specified as uniform as possible, is specified by specifying the pitch of the uneven portion of the surface. It has been found that it is possible to improve the image clarity of the surface of photographic paper coated with a photographic emulsion by making the thickness as uniform as possible.

The present invention provides a substrate of paper or synthetic paper, comprising
A resin-coated photographic support obtained by extrusion-molding a molten polyolefin resin at a speed of 0 m / min or more, wherein the resin-coated surface on the side on which the emulsion layer is provided has a surface wavelength of 0.08 mm. The following Rz is 0.3 to
It is 0.7 μm, preferably 0.4 to 0.5 μm. When Rz is larger than 0.7 μm, the image clarity of the surface of the photographic paper coated with the photographic emulsion is deteriorated.

The average pitch of the irregularities on the resin-coated surface of the present invention is 5 to 40 μm, preferably 10 to 20.
μm. If the average pitch is larger than 40 μm, waviness occurs on the surface of the photographic paper coated with the photographic emulsion, and the image clarity deteriorates.

Further, the relative load length t when CV / Rmax in the relative load curve of the resin-coated surface of the present invention is 30%.
p is 10 to 50%, preferably 20 to 40%. If tp is less than 10% or more than 50%, the height of the unevenness is not uniform, and waviness occurs on the surface of the photographic paper coated with the photographic emulsion, which lowers the image clarity.

Further, the method for producing the resin-coated photographic support of the present invention will be described in detail. In the present invention, 15
At the processing speed of 0 m / min or more, the surface of the cooling roll used for producing a resin-coated photographic support by extrusion-molding a molten polyolefin resin onto a paper or synthetic paper substrate has a surface wavelength of 0. With Rz of 0.8 mm or less,
0.8 to 1.2 μm, preferably 0.9 to 1.0
It is in the range of μm. If Rz is less than 0.8 μm,
When high-speed extrusion coating is applied, it is not possible to prevent peeling lateral unevenness and crater-like pores. The image clarity is reduced.

The average pitch of the irregularities on the surface of the cooling roll of the present invention is 5 to 30 μm, preferably 1
It is 0 to 20 μm. If the average pitch is larger than 30 μm, the slope of the uneven surface becomes gentle, the cooling area is small, and it is impossible to prevent unevenness of the lateral peeling. Further, a pitch of 50 μm or more is formed on the surface of the resin-coated photographic support, which lowers the image clarity. Conversely, the average pitch is 5
If it is smaller than μm, the low molecular weight component of the resin will be easily deposited on the surface of the cooling roll due to continuous operation, and this deposit will cause defective peeling, which will change the gloss of the surface of the photographic support and increase the product value. Is damaged.

The tp when the CV / Rmax in the relative load curve of the surface of the cooling roll in the present invention is 70% is 50 to 90%, preferably 60 to 80.
%. If the tp of the surface of the cooling roll is smaller than 50% or larger than 90%, the tp of the surface of the resin-coated photographic support is out of the range of 10 to 50%, and the image on the surface of the photographic paper coated with the photographic emulsion is imaged. Sex is reduced.

In the present invention, a thermoplastic resin such as polyethylene, polypropylene or a polyolefin copolymer is melt-extruded alone or in a mixture into a base material such as a paper made from natural pulp, a synthetic paper made of synthetic fibers or a mixed paper thereof. It is the one coated from the machine. The thickness of the resin coating layer is not particularly limited and is about 5 to 200 μm,
Particularly, about 15 to 50 μm is suitable. The preferred coating layer on the side where the emulsion layer is provided is titanium dioxide or a mixture of titanium dioxide and another white pigment or filler, and a polyethylene resin composition is particularly preferred. Further, a small amount of a colored pigment, a dye optical brightening agent, or other known additives may be contained. The polyethylene resin composition may be coated on one or both sides of the paper and is carried out at a temperature of 270-330 ° C. by extrusion coating moulding. The base material coated with the polyethylene mixture in the present invention may be added with a sizing agent, a paper strength enhancer, a coloring agent, an optical brightening agent and the like, if necessary. The basis weight of the base material is also not particularly limited and is about 50 to 300 g / m ² , and particularly 70 to
About 200 g / m ² is suitable.

Further, as a method for imparting the rough surface shape of the cooling roll used in the present invention, surface polishing of the roll,
Any method such as a vapor deposition method, a sandblast method, an etching method, an electroporation method, a plating method may be used, and the sandblast method is preferably used among these methods. First of all,
Any of the above methods is used to form fine irregularities on the surface. For example, 1 chrome plating on a roll material such as iron
The thickness is 0 to 200 μm. At this time, the surface is polished to be as smooth as possible, and then fine irregularities are formed by a sandblast method.

The surface treatment method of the cooling roll used in the present invention will be briefly described. A cooling roll base is applied on the surface of a roll material such as iron, grinder polishing is performed, buffing is performed, and then chrome plating is performed. Further, buffing is performed again, chrome plating is performed again for pinhole repair, and grinder polishing is performed. Finally, grind stone (mirror finish),
Sandblast and wash to a specified roughness.

Here, the sandblasting process of the present invention will be briefly described. Abrasive grain size, air pressure, abrasive grain nozzle diameter, gun nozzle diameter, gun feed rate, nozzle distance, roll rotation speed, number of times of processing (number of passes), etc. are appropriately carried out by setting conditions to obtain a predetermined cooling roll metal surface, The cooling roll surface shape of the present invention is obtained.

The cooling roll material of the present invention can be selected from various materials such as chromium-plated metal such as iron or nickel, enameled, stainless steel, Teflon processed,
Each material and the method of imprinting can be arbitrarily selected.

[0045]

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. A 1: 1 mixture of a hardwood bleached kraft pulp (LBKP) and a softwood bleached sulfite pulp (NBSP) was beaten to 300 ml with Canadian Standard Freeness to prepare a pulp slurry. Alkyl ketene dimer as a sizing agent to the pulp 0.5% by weight, polyacrylamide as a strength agent to the pulp 1.0% by weight,
Cationized starch was added to the pulp in an amount of 2.0% by weight, and polyamide epichlorohydrin was added to the pulp in an amount of 0.5% by weight, and diluted with water to prepare a 1% slurry. This slurry was made into paper by a Fourdrinier paper machine so as to have a basis weight of 170 g / m ² , and was used as a base paper for a polyolefin resin-coated paper.

[Examples 1 to 6] 100% by weight of low-density polyethylene having a density of 0.918 g / cm ³ was applied to the raw paper which was made into paper.
The polyethylene resin composition in which 10% by weight of anatase-type titanium is uniformly dispersed is melted at 320 ° C. and extruded to a thickness of 30 μm, and the metal surface of the cooling roll is a surface manufactured by Tokyo Seimitsu Co., Ltd. Roughness analyzer S
A high-speed extrusion coating was performed at a speed of 150 m / min or more using a cooling roll having the conditions shown in Table 1 having fine irregularities measured by urfcom E-RM-S27A type. The other side has a density of 0.962 g / cm ³
Similarly, the high density polyethylene resin of
It was extrusion-coated to a thickness of 30 μm.

[Quality Evaluation Method] Stripping lateral unevenness on the surface of the resin-coated photographic support thus obtained,
The degree of occurrence of crater-like pores was visually evaluated.
Further, the surface of this resin-coated photographic support was subjected to corona treatment, a silver halide emulsion for color was coated at 13 g / m ² , and the image clarity of the surface of the developed photographic printing paper was evaluated. [Peeling lateral unevenness] The peeling lateral unevenness is evaluated as grade. When 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 , It can be seen thinly on the emulsion layer Grade 5: peeling lateral unevenness is very strong and remains strongly on the emulsion layer. [Crater-like pores] Crater-like pores are evaluated on the surface of the resin-coated photographic support according to 2. The 0 cm square was observed with a 10-fold magnifying glass and the grade was evaluated by the number of pores with a diameter of 0.4 mm (measured 40 μm) or more. When the crater-like pore grade was 4 or more, the gloss of the photographic printing paper surface was measured. It causes a problem in appearance such as deterioration of Grade 1: No pores are observed on the surface Grade 2: 1 to 10 are seen Grade 3: 11 to 50 are seen Grade 4: 51 to 100 are seen Grade 5: 101 or more are seen [Image clarity The image clarity is measured by using Suga Test Instruments Co., Ltd. image clarity measuring instrument ICM-2DP type, and the width of the optical comb is 2.0.
It was evaluated using mm. The results of these evaluations are shown in Table 1. If the image clarity C value is less than 50%, the performance as a photographic printing paper having a mirror surface type and having a high gloss feeling is lacking, which causes a trouble in appearance.

[Comparative Examples 1 to 9] The metal surface of the cooling roll is a surface roughness analyzer Surfcom manufactured by Tokyo Seimitsu Co., Ltd.
Using a cooling roll having the conditions shown in Table 1 having fine irregularities measured by E-RM-S27A type, Table 1
Example 1 except for the cooling roll surface roughness shown in FIG.
Extrusion coating was performed under the same conditions as above.

[0049]

[Table 1]

As in Examples 1 to 6 of the present invention, using a cooling roll controlled to have a predetermined roughness, 150 m /
Even if it is produced at a high processing speed for min or more, the resulting resin-coated photographic support has few quality defects such as crater-shaped pores and peeling horizontal unevenness, and also as an emulsion-coated photographic printing paper. Has excellent image clarity, and a high glossy feeling can be obtained.

In Comparative Example 1, the processing speed was 100 m / mi.
Since the speed is as low as n, no quality failure occurs during high-speed processing, and a relatively good resin-coated photographic support can be manufactured. However, in Comparative Examples 2 to 5, although the image clarity on the emulsion surface was good, quality defects occurred, clear defect points were left on the emulsion surface, and defect defects that could not be products were obtained. Further, in Comparative Example 6, although the crater-like pores on the resin-coated photographic support and the image clarity of the emulsion surface were good, peeling lateral unevenness occurred, and horizontal unevenness also occurred on the emulsion surface. Occurs, which is an unacceptable level for photographic printing paper. Further, in Comparative Examples 7 to 9, no surface defects occurred on the resin-coated photographic support, and although it had a practical level, the image clarity as an emulsion-coated photographic printing paper decreased and the mirror surface A high gloss feeling as a type is not obtained, and a gloss feeling close to a matte tone is obtained. In particular,
In Example 9, the image clarity is remarkably deteriorated, and a photographic printing paper that is different from the mirror-type photographic printing paper and can obtain a gloss feeling similar to another matte tone is obtained.

[0052]

EFFECTS OF THE INVENTION By using the cooling roll of the present invention, the deposition of the resin component on the surface of the cooling roll is reduced even at the extrusion coating mold speed of 150 m / min, and the lateral peeling of the surface of the resin-coated photographic support is reduced. It is possible to prevent step unevenness and crater-like pores, maintain the high glossiness of the photographic printing paper after emulsion coating, and obtain a good surface as the photographic printing paper.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location D21H 19/80 19/20 G03C 1/765

Claims (2)

[Claims] 1. A substrate of paper or synthetic paper, 150 m / m
A resin-coated photographic support obtained by extrusion-molding a molten polyolefin resin at a speed of in or more, wherein the resin-coated surface on the side on which the emulsion layer is provided has a surface wavelength of 0.08 mm or less. , 10-point average roughness is 0.3-
0.7 μm, the average pitch is 5 to 40 μm, and
30% of cutting depth / maximum height in relative load curve
A resin-coated photographic support having a relative roughness of 10 to 50% in surface roughness. 2. In a method for producing a resin-coated photographic support in which a molten polyolefin resin is extrusion-coated on a paper or synthetic paper substrate, the extrusion-coating speed is 150 m.
/ Min or more, and the resin-coated surface on the side on which the emulsion layer is provided has a surface wavelength of 0.8 mm or less, a ten-point average roughness of 0.8 to 1.2 μm, and an average pitch of 5 to 30 μm. Further, the resin is characterized by being molded while being cooled by a cooling roll having a surface roughness of 50 to 90% in relative load length when the cutting depth / maximum height in the relative load curve is 70%. A method for producing a coated photographic support.