JPH063765A - Support for photographic paper - Google Patents

Abstract

(57) [Abstract] [Purpose] For a photographic printing paper support having both sides coated with a polyolefin resin, by applying a specific polyacrylamide to the surface of the photographic printing paper, it has excellent smoothness. Get the support. [Structure] By applying an anionic polyacrylamide having an average molecular weight of 3,000 or more and 100,000 or less, a target photographic paper support is obtained. The coating amount of the anionic polyacrylamide in the case of 0.05 g / m ² or more 1.0 g / m ² or less, or if it contains a cationic starch base paper, is excellent especially smoothness improvement effect. [Effect] The smoothness after coating with the polyolefin resin is excellent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photographic paper support having excellent surface smoothness.

[0002]

2. Description of the Related Art A photographic printing paper support is required to have a high level of smoothness, which is incomparable with so-called general paper such as printing paper, from the viewpoint of appearance and resolution of images. In recent years, the support for photographic printing paper is coated with a resin such as polyolefin on both sides of the base paper in order to improve the smoothness and prevent the processing solution from penetrating into the base paper layer to enable rapid development processing. Is becoming.

Unlike conventional baryta paper, the photographic paper using this type of photographic paper support does not undergo the ferro-type treatment of transferring the mirror surface when it is dried after development. The smoothness of the support is directly reflected on the smoothness of the printing paper after development and drying. Therefore, the demand for smoothness has become stricter than in the past.

As described above, since the support can be obtained by applying a resin such as polyolefin having a uniform thickness on both sides of the base paper with an extrusion coating machine or the like, the influence of the smoothness of the base paper is affected. Receive strongly. Techniques for improving the smoothness of the base paper are disclosed in JP-A-58-68037 and JP-A-6-6837.
As disclosed in Japanese Laid-Open Patent Application No. 2-54252, a method of adjusting the fiber length distribution of pulp used for the base paper within a certain range, and an optical method for pulp as disclosed in Japanese Patent Publication No. 59-42295. There is known a method of defining characteristics, and a method of adding a synthetic paper strengthening agent such as anionic polyacrylamide to a base paper by an impregnation treatment as disclosed in JP-A-2-203333.

[0005]

As described above, various attempts have been made for the purpose of improving the smoothness of the support for photographic printing paper in which both sides of the base paper are coated with a resin such as polyolefin. There is a limit to the improvement effect in adjusting the fiber length distribution, etc. Sufficient smoothness improvement effect cannot be obtained by the impregnation treatment of anionic polyacrylamide having a relatively large molecular weight which is generally used as a paper strengthening agent. In any of these methods, the intended support for photographic paper having excellent smoothness could not be obtained. That is, it is an object of the present invention to provide a support for photographic printing paper, which is obtained by coating both sides of a base paper with a polyolefin resin and has excellent smoothness.

[0006]

In order to solve the above problems, the inventors of the present invention traced changes in surface smoothness in each step of manufacturing a photographic printing paper support. As a result, it was found that when the high temperature molten resin comes into contact with the surface of the base paper during extrusion coating of the polyolefin resin, uneven contraction of the surface and calendering action at the roll nip occur simultaneously, resulting in a change in smoothness. Also, suppressing uneven shrinkage of the surface,
It was found that it is even more important than the smoothness of the base paper before extrusion coating.

Further, in order to reduce the shrinkage of the surface during the extrusion coating, the average molecular weight of the surface of the raw paper is 300.
It has been found that applying an anionic polyacrylamide having a relatively low molecular weight of 0 or more and 100,000 or less is most effective, and has completed the present invention. The reason for this is that the low molecular weight anionic polyacrylamide penetrates well into the pulp fiber wall existing near the surface and strengthens the intrafiber bond, so that swelling in the width direction of the fiber due to subsequent temperature or moisture content changes. It is thought that there is less shrinkage.

The base paper for the photographic printing paper support of the present invention comprises:
NBKP, LBKP, NBSP, LBSP, various non-wood pulp, etc. can be used. Also, antifoggants, dyes,
A filler, a sizing agent, a fixing agent, a dry paper strength enhancer, a wet paper strength enhancer and the like are optionally contained.

As the anionic polyacrylamide to be applied to the surface of the raw paper in the present invention, those having an average molecular weight of 3,000 or more and 100,000 or less, which are lower in molecular weight than ordinary paper strengthening agents are used. These anionic polyacrylamides are
Those obtained by partially hydrolyzing the amide group in polyacrylamide, or copolymers of acrylamide and acrylic acid can be used. It is also possible to use a copolymer using methacrylic acid or maleic anhydride instead of acrylic acid, or a terpolymer containing acrylonitrile or an acrylic ester as the third component.

[0010] The coating amount of the anionic polyacrylamide of the present invention is preferably 0.05 g / m ² or more 1.0 g / m ² or less. When the coating amount is less than 0.05 g / m ^2, sufficient smoothness improving effect cannot be obtained, and 1.0 g / m 2
^When it exceeds ² , the smoothness improving effect is rather deteriorated, which is not preferable. In addition, anionic polyacrylamide,
It is also possible to coat the raw paper with various surface-strengthening agents such as starch, polyvinyl alcohol and gelatin, and antistatic treatment agents such as Glauber's salt, sodium chloride, aluminum chloride and organic conductive agents.

When a cationic starch is contained in the base paper coated with the anionic polyacrylamide of the present invention, a particularly excellent smoothness improving effect can be obtained. In the base paper containing the cationic starch, the anionic polyacrylamide is localized near the surface, so that it is considered that the smoothness improving effect is enhanced.

As the polyolefin resin of the present invention, a homopolymer of α-olefin such as ethylene or propylene, a copolymer of two or more kinds of α-olefins or an α-olefin as a main component and copolymerizable therewith Copolymers with other monomers, and mixtures thereof can be used. It is also possible to add white pigments or coloring pigments such as titanium dioxide, alumina and calcium carbonate to these resins, and to add stabilizers, antioxidants, dispersants, lubricants and the like, which are usually mixed with the resin. . The polyolefin resin-coated photographic printing paper support of the present invention casts a heat-melted resin on a running base paper,
It is manufactured by a so-called extrusion coating method.

The photographic printing paper support having excellent smoothness according to the present invention can be used for color printing paper, black-and-white printing paper, typesetting printing paper, copy printing paper, plate-making printing paper and the like. .

[0014]

The average molecular weight of the base paper of the present invention is 3000
The support for a photographic printing paper coated with a polyolefin resin, which is characterized by coating 100,000 or less of anionic polyacrylamide, has a low molecular weight anionic polyacrylamide that penetrates well into the pulp fiber wall to strengthen the intrafiber bond. Therefore, the surface of the base paper is less likely to shrink due to changes in the temperature or the water content during extrusion coating of the polyolefin resin, resulting in excellent smoothness.

[0015]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples. The present invention is not limited to the examples. All parts and% in the following are by weight.

Example 1 A laboratory disc refiner provided a freeness of 350 m.
2.0 parts of cationic starch (Kate F, manufactured by Oji National Co.) and 100 parts of alkyl ketene dimer sizing agent (HACON 11 -2, Dick-
Hercules) (0.4 parts) and polyamide-polyamine-epichlorohydrin resin (Kaymen S25, Dick-Hercules) (0.50%) were added, and the basis weight was 18
A 0 g / m ² handsheet was prepared. The sheet was dried at 100 ° C. for 10 minutes.

Each of these sheets was subjected to tab size treatment with a 1% aqueous solution of anionic polyacrylamide having different average molecular weights of 3000, 10,000 and 100,000 measured by a viscosity method. The coating amount at that time was 0.2 g / m ² in all the samples. After smoothing with a super calender, these samples were made of low-density polyethylene containing 10% titanium dioxide on the front surface and low-density polyethylene on the back surface at a thickness of 32 μm and a resin temperature of 3 μm.
Extrusion coating was carried out under the condition of 20 degrees to obtain a support for photographic printing paper. These samples are referred to as Samples 1-2, 1-3, and 1-4 in order of decreasing anionic polyacrylamide molecular weight.

Comparative Example 1 A support for photographic printing paper was obtained in the same manner as in Example 1, except that the molecular weights of the anionic polyacrylamides were 2000 and 200,000. These samples are referred to as Sample 1
-1 and 1-5. The above results are collectively shown in Table 1.

Example 2 In Example 1, the molecular weight of the anionic polyacrylamide was set to 10,000 and the concentration of the aqueous solution was changed so that the coating amount was 0.03, 0.05, 1.00, and 1.20 g. A support for photographic printing paper was obtained by the same method except that it was changed to 4 levels of / m ² . Samples 2-1, 2-2, and
2-3 and 2-4. The above results are shown in Table 2.

Example 3 In Example 1, 0.3 part of anionic polyacrylamide (Stargum A-15, manufactured by Hoshiko Kagaku Co.) was used in place of the cationic starch, or a cationic polyacrylamide strength enhancer (Polystron 677). Arakawa Kagaku Co., Ltd.) was added to a sheet, and a photographic printing paper support was obtained by the same method except that an anionic polyacrylamide having a molecular weight of 10,000 was coated. These samples are referred to as sample 3-
1 and 3-2.

Comparative Example 2 Same as Example 1 except that polyvinyl alcohol or cationic polyacrylamide having a molecular weight of 10,000 was applied to the same sheet as Example 1 in the same coating amount as in Example 1. A support for photographic printing paper was obtained by the method described in 1. These samples are referred to as Samples 3-3 and 3-
Set to 4. The above results are summarized in Table 3.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

The surface roughness in Tables 1, 2 and 3 means
According to JIS B0601, using a stylus type roughness meter, the center line average roughness (μ of the surface of the photographic printing paper support was measured under the conditions of a measurement length of 2.5 mm and a cutoff value of 0.8 mm.
The value of m). In addition, the appearance is a visual evaluation result of smoothness, where A is the best smoothness and D is the worst. As a photographic support, the surface roughness is 0.2.
It should be 0 μm or less, preferably 0.18 μm or less, and appearance C or more, preferably B or more (A, B).

The results shown in Table 1 show that by applying an anionic polyacrylamide having a molecular weight of 3000 to 100,000 to a sheet containing cationic starch, a support for photographic printing paper having excellent smoothness can be obtained. Shows. Results of the samples 1-3 and Table 2, obtained especially smoothness of excellent photographic printing paper support when the coating weight of the anionic polyacrylamide is 0.05 g / m ² or more 1.0 g / m ² or less Is shown.

From the comparison between Sample 1-3 and Samples 3-1 and 3-2, it is understood that a photographic printing paper support having particularly smoothness can be obtained when the raw paper contains cationic starch. In addition, from the comparison between Sample 1-3 and Samples 3-3 and 3-4, it is possible to obtain a support for photographic printing paper which is superior in smoothness to the case where other chemicals are applied by applying anionic polyacrylamide. Is clear.

[0028]

From the above results, the use of anionic polyacrylamide having an average molecular weight of 3000 or more and 100,000 or less on the surface of the base paper as in the present invention makes it possible to produce a polyolefin resin-coated photographic printing paper excellent in smoothness. It is clear that a support is obtained.

Front page continuation (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location D21H 19/20 17/28 27/00 7199-3B D21H 5/00 Z

Claims (3)

[Claims] 1. A photographic printing paper support comprising both surfaces of a base paper coated with a polyolefin resin, wherein the surface of the base paper is coated with an anionic polyacrylamide having an average molecular weight of 3,000 or more and 100,000 or less. Support for paper. Wherein the anionic coating weight of polyacrylamide, 0.05 g / m ² or more 1.0 g / m ² photographic printing paper support of claim 1, wherein the less. 3. The photographic paper support according to claim 1, wherein the base paper coated with the anionic polyacrylamide contains cationic starch.