JPH0619045A - Supporting body for photographic printing paper - Google Patents

Abstract

PURPOSE:To provide a supporting body for a photographic printing paper excellent in water resistance, whiteness and surface smoothness which hardly shows curling with the lapse of time. CONSTITUTION:The one surface of the base paper is coated with a compsn. prepared by mixing and dispersing titanium oxide in polyethylene terephthalate or in the mixture resin of polyethylene terephthalate and other resin. The other surface of the base paper is coated with a compsn. prepared by mixing and dispersing calcium carbonate in polyethylene terephthalate or in the mixture resin of polyethylene terephthalate and other resin.

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 is less prone to curling over time.

[0002]

2. Description of the Related Art Conventionally, in photographic printing paper, in order to improve water resistance and light reflection efficiency, the emulsion coating side of the base paper is coated with a polyolefin resin layer such as polyethylene containing titanium oxide mixed and dispersed. Is being done. In this case, titanium oxide enhances the image quality by increasing the whiteness of the photographic paper in particular, while it works to deteriorate the flatness of the surface of the photographic paper.

[0003]

However, in a photographic printing paper having a glossy surface, which is most popularly used at present, in order to improve the appearance of the image, the flatness and glossiness of the surface of the printing paper are further improved. It is desired to improve. Therefore, when polyethylene terephthalate is used instead of polyolefin, good results can be obtained. However, even in this case, there is a drawback that a curling tendency is apt to occur over time.

The inventors of the present invention have conducted extensive studies to solve the above-mentioned drawbacks, and as a result, a composition prepared by mixing and dispersing titanium oxide in polyethylene terephthalate or a resin containing polyethylene terephthalate as a main component was applied to the emulsion-coated side of the base paper. While coating, the other surface, by coating a composition in which calcium carbonate is mixed and dispersed in polyethylene terephthalate or a resin containing polyethylene terephthalate as a main component, it is found that curl can be improved,
The present invention has been reached. Therefore, the object of the present invention is to provide water resistance,
Another object of the present invention is to provide a support for photographic printing paper, which is excellent in whiteness and surface smoothness and is less likely to have a curling tendency over time.

[0005]

The above objects of the present invention are as follows.
Polyethylene terephthalate or a resin in which polyethylene terephthalate and another resin are mixed and dispersed, and a composition in which titanium oxide is mixed and dispersed are coated on one surface of the base paper, and the other surface of the base paper is polyethylene terephthalate or polyethylene terephthalate and other This is achieved by a support for photographic printing paper, which is obtained by coating a resin obtained by mixing and dispersing the above resin with a composition in which calcium carbonate is mixed and dispersed.

Other resins to be added to polyethylene terephthalate (referred to as blend resins) include polyolefin resins such as polyethylene and polypropylene, polyether resins such as polyethylene glycol, polyoxymethylene and polyoxypropylene, polyester-based polyurethane and polyether polyurethane. The resin can be appropriately selected and used from resins that can be extruded at 270 to 350 ° C., such as urethane resin, polycarbonate and polystyrene. Two or more kinds of the above blended resins may be used at the same time.

The mixing ratio of the polyethylene terephthalate and the blend resin is appropriately determined depending on the degree of polymerization and the kind of the blend resin to be used. In the case of the polyolefin resin, the blend ratio of the blend resin to the polyethylene terephthalate is 100: by weight. It is preferably in the range of 0 to 80:20. When the blended resin is mixed in an amount of 20% by weight or more, the resulting photographic printing paper support has low rigidity and insufficient surface smoothness.

When a resin other than the polyolefin resin is used as the blend resin, the mixing ratio is 100: 0 to 40:
It can be in the range of 60. 60% of the blended resin
When it is mixed in an amount of not less than wt%, it is not possible to sufficiently prevent the curl of the support for photographic printing paper over time.

The form of titanium oxide used in the present invention may be either anatase type or rutile type.
The average particle size is preferably 0.1 to 0.8 μm. When it is 0.1 μm or less, it becomes difficult to uniformly mix and disperse it in the resin layer, and when it is 0.8 μm or more, the smoothness of the surface of the photographic printing paper support cannot be obtained and it is white. The degree is insufficient. The content of titanium oxide in the composition is preferably 2 to 20% by weight.

The average particle size of the calcium carbonate used in the present invention is preferably 0.01 to 1.5 μm. 0.01 μm
In the following cases, it becomes difficult to mix and disperse as in the case of titanium oxide, and when it is 1.5 μm or more, the smoothness of the surface of the support for photographic printing paper cannot be obtained. The content of calcium carbonate in the composition is preferably in the range of 1 to 30% by weight. The type of calcium carbonate may be any of vaterite, calcite, and aragonite, and may have any shape such as a shape close to a true sphere, a needle shape, or a go stone shape. The resin such as polyethylene terephthalate and titanium oxide or calcium oxide can be easily mixed according to a conventional method.

In producing the photographic paper support of the present invention, one side of the base paper is coated with a mixed composition of polyethylene terephthalate or a resin obtained by mixing polyethylene terephthalate or another blended resin with titanium oxide. At the very least, this can be used as an emulsion coated surface, and the other surface can be coated with a mixed composition of polyethylene terephthalate or a resin obtained by mixing polyethylene terephthalate or another blended resin with calcium carbonate.

The thickness of the resin layer covering the base paper is 5 to 5 mm, respectively.
The thickness is preferably in the range of 50 μm, particularly 15 to 35
It is preferably in the range of μm. When the thickness is 50 μm or more, the coating layer is apt to crack, and the thickness is 5 μm.
When it is m or less, the waterproofness of the support for photographic printing paper is insufficient and the rigidity is lowered, which is not preferable. Further, from the viewpoint of sufficiently preventing curl, it is preferable that the coating layers on both surfaces have substantially the same thickness.

When the base paper is coated with the above-mentioned mixed composition, the surface of the base paper may be pretreated by corona discharge treatment or undercoating. By coating a photographic emulsion layer on the titanium oxide-containing composition coating layer of the support obtained as described above in a known manner, a photographic printing paper excellent in whiteness and glossiness as well as water resistance can be obtained. Obtainable.

[0014]

EFFECTS OF THE INVENTION The support of the present invention has a water resistance and a whiteness which are different from those of conventional ones because the surface of the base paper is coated with a resin containing polyethylene terephthalate as a main component, which is originally superior in surface smoothness to polyolefin. While keeping the same,
The smoothness of the surface is improved and the glossiness becomes excellent.
Further, one side of the base paper is coated with a composition containing polyethylene terephthalate as a main component and a composition containing titanium oxide, and the other side is coated with a composition containing polyethylene terephthalate as a main component with calcium carbonate. Therefore, it is extremely unlikely that a curling habit is generated over time.

[0015]

EXAMPLES The present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

Examples 1-5 and Comparative Example 1. Thickness 180μ
m of the base paper, the titanium oxide-containing resin composition shown in Table 1 on one surface, the calcium carbonate-containing resin composition on the other surface are melt-extruded at 300 ° C. to form a laminate layer of 25 to 38 μm, The results of evaluating the curl of the obtained support are as shown in Table 1.

For the evaluation of curl, a plurality of samples were wound around the core having a diameter of 10 cm and the support was left for 6 hours in an environment of 50 ° C., and the curl was 5 cm in length × 5 cm in width. When the sample of (1) was placed on a horizontal plate, the height (36 points including the four corners of the sample) of the sample from the horizontal plate was measured every 1 cm in the vertical and horizontal directions, and the standard deviation was used.

[0018]

[Table 1]

Claims (1)

[Claims] 1. A resin comprising polyethylene terephthalate or a mixture of polyethylene terephthalate and another resin,
A composition obtained by coating one side of a base paper with a composition obtained by mixing and dispersing titanium oxide, and mixing and dispersing calcium carbonate in a resin obtained by mixing polyethylene terephthalate or polyethylene terephthalate and another resin on the other side of the base paper. A support for photographic printing paper, which is formed by covering things.