JPH0557577B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to photographic resin-coated papers with improved suitability for high speed coating of emulsions. Today's resin-coated paper for photographs is generally made of water-resistant resin-coated paper, which is coated with molten resin on both sides of the paper, and then the resin layer is rolled over a cooling roll. It is manufactured using the so-called extrusion coating method, in which the coating is cooled and solidified while being pressure-bonded. The surface shapes of photographic paper using this photographic resin-coated paper include a smooth glossy surface, a matte surface, a silky surface, a fine-grained surface, and the like. These photographic papers having different surface shapes can be obtained by using photographic resin-coated paper having a surface shape corresponding to the surface shape. Photographic paper is coated with a single layer or multiple layers such as a silver halide photographic emulsion layer, a protective layer, a subbing layer, an intermediate layer, an antihalation layer, and an ultraviolet absorbing layer on these photographic resin-coated papers. Color photographic paper is coated with multiple emulsion layers such as a blue-sensitive emulsion layer and an intermediate layer, a green-sensitive emulsion layer and an intermediate layer, and a red-sensitive emulsion layer and a protective layer. Recently, from the viewpoint of cost and productivity, it has become common practice to apply multiple layers at once. For example, it has become possible to coat many layers at once using coating methods such as the slide hopper method and curtain coat method. Furthermore, it is important to increase productivity by coating these emulsions at high speeds, and various studies have been made. Photographic resin-coated paper is hydrophobic, and in order to apply a hydrophilic emulsion layer, it is well known and widely used to make the surface on which the emulsion layer is applied hydrophilic by corona discharge treatment, fire treatment, etc. ing. For photographic resin-coated paper with a smooth glossy surface during emulsion coating, the coating speed is 100 m/min to 200 m/min.
It is carried out in minutes. However, with photographic resin-coated paper that has a rough surface such as a matte surface, silky texture, or fine-grained surface, when the emulsion coating speed is increased to 100 m/min or more, the emulsion layer shifts (hereinafter referred to as emulsion layer shift), resulting in a coating failure. Coating failures such as emulsion repellency and emulsion repellency may occur. If coating failures such as emulsion layer misalignment or emulsion repelling occur, when processed as photographic paper, color shading or color misalignment will occur, resulting in a significant quality deterioration in the performance of the photographic paper, resulting in a serious defect. Here, the rough surface of photographic resin-coated paper refers to paper that has irregularities on a flat surface, or paper that has irregularities on a patterned surface such as silky or fine-grained paper (i.e., a paper that has an emulsion layer). When used as photographic paper, the gloss of the photographic paper is 75
It is a so-called molded product with a low gloss surface of less than %. ), and is usually obtained by providing irregularities on the surface of a cooling roll in an extrusion coating process. That is, it can be obtained by providing unevenness on the flat surface of the cooling roll, or by embossing the cooling roll with texture, fine-grained surface, etc. and further providing unevenness. The degree of roughness can be selected depending on the purpose such as gloss. In addition, the degree of roughness can be selected as necessary to adjust the texture, fine-grained surface, etc., uneven feeding of the embossing, adjust gloss, and prevent glare. When applying emulsion to the surface of this roughened photographic resin-coated paper, increasing the coating speed will cause coating failures such as emulsion layer displacement and emulsion repellency, so it is not possible to increase the coating speed beyond a certain level. Productivity is poor. Various causes can be considered for coating failures such as emulsion layer shift and emulsion repellency. For example, it may be due to uneven treatment or insufficient treatment such as corona treatment on the surface of photographic resin-coated paper. However, even if processing unevenness is reduced, when the coating speed of photographic resin-coated paper with a rough surface is increased, emulsion layer displacement and emulsion repellency occur. Furthermore, even if the surface is sufficiently treated and applied before attenuation, the application speed will not increase. However, it was discovered that the coating speed increases when the rough surface shape of the roughened photographic resin-coated paper is rounded, and after further research, the present invention was completed. That is, we have invented a photographic resin-coated paper characterized in that the surface to which a photographic emulsion is coated has a rough surface composed of a plurality of curved surfaces curved toward the resin layer side.
The rough surface shape of the conventional roughened photographic resin-coated paper has a mountain-like unevenness in which the convex portions have irregular edges. On the other hand, the roughened photographic resin-coated paper of the present invention has irregularities composed of a plurality of curved surfaces curved toward the resin layer side. These rough surface shapes can be identified as clear differences from photographs taken at 100x or 1000x using a scanning electron microscope.
(See Figures 3 to 6, Figures 9 to 12, and Figures 15 to 18.) By controlling the size, number, etc. of the unevenness, which is composed of multiple curved surfaces curved toward the resin layer side, it is possible to Similar to the rough surface, the quality of the photographic paper, such as gloss and texture, can be satisfied. When the emulsion coating speed is 100 m/min or less, emulsion layer displacement and emulsion repellency do not occur, but as the coating speed increases, emulsion layer displacement and emulsion repellency occur. The cause of emulsion layer shift and emulsion repellency is not clear, but the following may be considered. In other words, when the rough surface has a mountain-like unevenness with irregular edges, air is easily retained between the mountain-like unevenness, and as the coating speed increases, the emulsion layer is placed on the rough surface. In this case, it is estimated that the emulsion layer and the air cannot be replaced sufficiently, resulting in misalignment of the emulsion layer, or that the air expands during drying, resulting in emulsion repellency. on the other hand,
Since the uneven surface is made up of a plurality of curved surfaces curved toward the resin layer, the surface is smooth, so air can be sufficiently replaced with the emulsion layer even during high-speed coating, and it is thought that emulsion layer shift and emulsion repellency are less likely to occur. The paper support for the photographic resin-coated paper used in the present invention is usually made of pulp mainly composed of natural pulp. Depending on the case, synthetic pulp, synthetic fibers, etc. may be mixed or used alone. The paper support contains a sizing agent, a strength agent, a fluorescent agent, an antistatic agent, etc., and whether or not to use them is selected depending on the purpose. Further, the resin used in the present invention may be any resin such as thermoplastic or thermosetting resin as long as it can be imprinted with a mold. Preferred is polyolefin resin, particularly preferred is polyethylene. There is no particular limit to the thickness of the resin layer, but it is obvious that it needs to be thick enough to copy the surface shape of the roll. In order to obtain the rough surface composed of a plurality of curved surfaces curved toward the resin layer side of the present invention, the method described below is preferable, but the method is not limited thereto. For example, on the matte surface, the iron core roll is copper-plated or not, and the flat surface is sandblasted or liquid honed to form fine irregularities on the copper-plated surface or the iron core roll, and the rough surface is become Once the required roughness is achieved, apply plating.
Any plating may be used at this time, but chrome plating is preferred from the viewpoint of operability, and hard chrome plating is particularly preferred. The thickness of the plating layer is preferably 1μ to 50μ. Using the roll thus obtained, a resin-coated paper with a matte surface having a rough surface composed of a plurality of curved surfaces curved toward the resin layer side is obtained. If the thickness of the plating layer is less than 10μ, the rough surface composed of multiple curved surfaces on the resin layer side will be incomplete and a mountain-like rough surface with irregular edges will remain, resulting in high-speed coating. Above, I don't like it. Also 50μ
If it is larger, the gloss will change after coating the emulsion, which is undesirable. In addition, for silky texture, the iron core roll is either copper-plated or not, and the uniform surface is embossed little by little using a tortoise-shell pattern embossing roll. After that, finer irregularities are formed on the embossed mold using sandblasting or liquid honing.
Perform surface roughening. After that, perform the metsuki. As with the mat surface, the plating is preferably chrome plating, especially hard chrome plating. The thickness of the matte layer is
10μ to 50μ is preferable. Using the roll thus obtained, a silky resin-coated paper having a rough surface composed of a plurality of curved surfaces curved toward the resin layer is obtained. If the thickness of the plating layer is less than 10 μm, the rough surface composed of a plurality of curved surfaces curved toward the resin layer side will be incomplete, and a mountain-like rough surface will remain, which is undesirable for high-speed coating. Moreover, if it is larger than 50μ, the gloss will change, which is not preferable for achieving the desired texture. There are no special conditions regarding the plating method, and a commonly used plating method may be used. However, in order to control the thickness, processing conditions, plating bath temperature, electric current, etc. must be carefully controlled. The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the Examples. Example 64 parts by weight of low-density polyethylene with a density of ^0.92 , 25 parts by weight of high-density polyethylene with a density of 0.96, 10 parts by weight of anatase-type titanium, blue Additives such as flavor pigments and resin stabilizers to add 1 part by weight of resin, and on the other side, 50 parts by weight of low-density polyethylene with a density of 0.92 and 50 parts by weight of high-density polyethylene with a density of 0.96. Extrude and coat 30μ of each part by weight of resin formulation. During extrusion coating, the shape of the surface to which the emulsion is applied was made into three types: a matte surface, a fine-grained surface, and a silky surface having a rough surface composed of a plurality of curved surfaces curved toward the resin layer side. Similarly, three types of surfaces were prepared for comparison: a pine surface having a mountain-like rough surface with irregular convex edges, a fine-grained surface, and a silky surface. The surfaces to be coated with each emulsion were subjected to corona discharge treatment under the same conditions, and then the emulsion was coated. The emulsion coating speed was changed to four levels as shown in Table 1, and coating failures such as emulsion layer shift and emulsion repellency were evaluated. As a result, as shown in Table 1, photographic resin-coated paper having a rough surface shape consisting of a plurality of curved surfaces curved toward the resin layer can be coated at high speed, and the effects of the present invention are obvious. 【table】

[Brief explanation of drawings]

FIG. 1 is a stereoscopic micrograph of the surface of the resin-coated paper of Invention Example-1 among Examples, magnified 20 times. FIG. 2 is a stereoscopic micrograph of the surface of the resin-coated paper of Comparative Example-1 in the Examples, magnified 20 times. Figure 3 shows an example of the invention among the examples.
This is a 100x scanning electron micrograph of the resin-coated paper surface of No. 1. FIG. 4 is a scanning electron micrograph of the surface of the resin-coated paper of Comparative Example-1 in the Examples, magnified 100 times. FIG. 5 is a scanning electron micrograph of the surface of the resin-coated paper of Invention Example-1 among Examples, magnified 1000 times.
FIG. 6 is a scanning electron micrograph of the surface of the resin-coated paper of Comparative Example-1 in the Examples, magnified 1000 times. FIG. 7 is a stereoscopic micrograph of the surface of the resin-coated paper of Invention Example-2 in Examples, magnified 20 times. FIG. 8 is a stereoscopic micrograph of the surface of the resin-coated paper of Comparative Example-2 in the Examples, magnified 20 times. FIG. 9 is a 100x scanning electron micrograph of the resin-coated paper surface of Invention Example-2 among Examples. FIG. 10 is a 100x scanning electron micrograph of the surface of the resin-coated paper of Comparative Example-2 in the Examples.
FIG. 11 is a scanning electron micrograph of the surface of the resin-coated paper of Invention Example-2 among Examples, magnified 1000 times. 1st
Figure 2 shows the surface of the resin-coated paper of Comparative Example-2 in the Examples.
This is a scanning electron micrograph at 1000x magnification. FIG. 13 is a stereoscopic micrograph of the surface of the resin-coated paper of Invention Example-3 in Examples, magnified 20 times. FIG. 14 shows in the example,
This is a stereoscopic micrograph of the surface of the resin-coated paper of Comparative Example-3, magnified 20 times. FIG. 15 is a 100x scanning electron micrograph of the resin-coated paper surface of Invention Example-3 among Examples. FIG. 16 is a 100x scanning electron micrograph of the surface of the resin-coated paper of Comparative Example-3 in the Examples. FIG. 17 is a scanning electron micrograph of the surface of the resin-coated paper of Invention Example-3 among Examples, magnified 1000 times.
FIG. 18 is a scanning electron micrograph of the surface of the resin-coated paper of Comparative Example 3 in Examples, magnified 1000 times.

Claims (1)

[Claims] 1. In a photographic resin-coated paper in which both sides of the paper are coated with resin by an extrusion coating method and the gloss of the photographic paper is 75% or less, the surface to which the photographic emulsion layer is applied is roughened. 1. A photographic resin-coated paper characterized in that it has a rough surface formed by a plurality of curved surfaces curved toward the resin layer side by using a cooling roll that is then plated. 2. The photographic resin-coated paper according to claim 1, wherein the rough surface is a fine-grained surface, a matte surface, or a silky surface. 3. The photographic resin-coated paper according to claim 1, wherein the plating of the cooling roll is chrome plating having a thickness of 10 μm to 50 μm. 4. The photographic resin-coated paper according to claim 1 or 3, wherein the roughening of the cooling roll is sandblasting. 5. The photographic resin-coated paper according to claim 1 or 3, wherein the surface roughening of the cooling roll is liquid honing.