DE2148146A1 - Waterproof support for a photographic paper - Google Patents

Description

FATEKTAUWXLTE

DR. E. WIEGAND DIPL-ING. W. NIEMANN 2148146

DR. M. KÖHLER DIPL-ING. C. GERNHARDT

MDNCHEN HAMBURG

TELEPHONE: 55547 « 8000 MÖNCHEN 15,

TELEGRAMS: KARPATENT NUSSBAUMSTRASSE 10

W. 40 733/71 13 / Gtz September 27, 1971

Fuji Photo Film Co., Ltd. Ashigara-Kamigun, Kanagawa, (Japan)

Waterproof support for photographic paper

The invention relates to a support for photographic paper.

Heretofore, barite paper has been widely used as a support for photographic paper. It owns however, the disadvantage that during the treatment or processing, for example development or Fixation, the treatment liquid penetrates the paper and a decrease in the treatment speed or cause the paper to turn yellow with the passage of time. Hence the barite paper was from a resin coated paper, which is displaced by coating both surfaces of the paper made with a resin such as polyethylene to make it waterproof. Pas resin-coated paper is usually made by an extrusion coating process.

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When the side of a resin-coated paper as a support on which a photographic emulsion is applied is to be, a transparent resin on v / eist, light penetrates through the emulsion layer, at the time of the image groupings through a layer of the resin and becomes on the surface of the paper is diffusely reflected and in turn reaches the emulsion layer. Because of this, the picture becomes blurry and the resolving power is lowered.

In the method of opacifying the resin, it is common practice to use an inorganic pigment such as zinc oxide, titanium oxide or incorporate zinc sulfite into the resin. Titanium oxide is the most widely used inorganic pigment due to its excellent whiteness and high hiding power. To further explain the invention reference is made to the drawing.

FIG. 1 shows a sectional view of a conventional support for photographic papers.

FIG. 2 shows a sectional view of a support for photographic papers according to the invention.

FIG. 3 shows a schematic representation of a method for producing a carrier according to the invention.

Referring to Fig. 1, a resin-coated paper as a support consists of a paper T, a resin layer 2, around the back (surface on which no photographic emulsion is applied as a coating) waterproof, and a resin layer 3 to the surface (surface on which a photographic Emulsion is to be applied as a coating) to make it waterproof. The resin layer 3 contains an inorganic one Pigment, e.g., titanium oxide, for the reasons described above. The opacity of the resin is tried to reduce the To prevent blurring of the image.

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The production of such a resin-coated paper poses the following two problems.

1) The inorganic pigment promotes the decomposition and oxidation of the resin at the time of extrusion coating of the resin. In order to coat a resin on the surface of paper with sufficient bonding strength between the paper and the resin layer, it is necessary to raise the temperature of the resin sufficiently. However, the increase in the resin temperature leads to a remarkable increase in decomposition and oxidation, particularly when an inorganic pigment is incorporated in the resin . The decomposition and oxidation products of the resin in turn cause fogging of the photographic emulsion. Desirably, the temperature of the resin should therefore be kept as low as possible.

2) A resin with an inorganic pigment incorporated therein is very expensive because of the cost of the inorganic pigment and the cost of incorporating the pigment into the resin, which cost is added to the cost of the resin itself. Accordingly, the use of too much resin containing an inorganic pigment leads to an increased cost of the photographic paper. The amount of an inorganic pigment-containing resin used in the manufacture of resin-coated paper should be kept to a minimum. An attempt to reduce the amount of the inorganic pigment-containing resin by reducing the thickness of the resin layer cannot be applied to the manufacture of a support for photographic papers because of poor surface smoothness of the resin layer, decreased bonding strength between the paper and the resin layer and hence the need to raise the temperature of the resin. 209814/1535

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According to the invention, the above has been achieved Problem solved in that a coating made of a resin double layer on one side of the paper on which a photographic emulsion is to be applied as a coating, is provided, an inorganic Pigment only in the one layer that is closer to the photographic emulsion layer to be applied is, has been incorporated.

With reference to FIG. 2, the carrier according to FIG Invention from a paper 1, a resin layer 2, to the back (surface on which no photographic Emulsion is applied as a coating) waterproof to make a resin layer 3 that is not inorganic Contains pigment around the top (surface on which a photographic emulsion is used as a coating is to be applied) to make waterproof and a resin layer 4, which consists of a resin that has been made opaque by the incorporation of an inorganic pigment such as titanium oxide, which Layer also serves to make the top surface waterproof. The sum of the thickness of the layers 3 and 4 (total thickness) should be sufficient to make the surface of the support smooth. Since layer 3 contains no inorganic pigment and is not in direct contact with a photographic emulsion layer is present, the plating or coating can be carried out at temperatures sufficiently high to to obtain sufficient bond strength between this layer and the paper. Layer 4 will applied to the layer 3 as a coating, and therefore sufficient bonding strength can be obtained even if the coating is carried out at relatively low temperatures. It is therefore possible increased decomposition and oxidation of the resin caused by the incorporation of an inorganic Pigment caused to prevent.

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In the manufacture of the support according to the invention, the layer 3 and the layer 4 can be applied one after the other in sequence. The covering or coating can be carried out of the illustrated in Figure 3 functioning according to the "Eoextrudierverfahren ¹¹ also to the invention. Here, a resin containing no inorganic pigment, establishment of an extrusion pressed 5 and a resin having a content of inorganic pigments is from the Extruder 6. These two types of resins are introduced into the injection mold 7 and extruded in the form of a two-layer film 8, which is then applied to a paper 1 as a coating.

A highly flowable resin can be used as layer 3 to ensure good adhesion to the paper to obtain. The resin constituting the layer 4 may of course be a dye or a fluorescent dye included to regulate the color or whiteness of the support.

The invention is explained in more detail below with the aid of examples.

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example 1

A polyethylene with a density of 0.919 g / cm ⁵ and a melt index of 7 (Sumikathene L-705, Sumitomo Chemical Co., Ltd.) was on a high quality paper with a basis weight of 170 g / m at 335 ⁰ C in a Thickness of 30 'Ji applied as a coating. Was on the top of this coating a polyethylene having a thickness of 0.925 g / cm and a melt index of 2 (Sumikathene L-211, Sumitomo Chemical Co., Ltd.) with a titanium oxide content of 10% at 280 ⁰ C in a thickness applied by 10 u. The total thickness was 40 p. The coated or coated product was named Sample 1.

A polyethylene having a density of 0.925 g / cm ⁵ and a melt index of 2 (Sumikathene L-211) as described above, having a content of 7.5% titanium oxide was coated on a paper of the same quality at 32O ⁰ C in a thickness applied from 40 li as a coating. The product thus obtained was called a sample.

The back of both samples 1 and 2 was coated with polyethylene with a density of 0.925 g / cm (Sumikathene L-211) at 320 ° C in a thickness of 40 u as a coating upset. The bonding strength between the paper surface and the resin layer was measured using a test device (Schopper's tester), the following results being obtained:

Sample 1: No peeling between the paper and polyethylene.

Sample 2: 148 g (peel between the paper and polyethylene).

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The photographic emulsion was aufgebrächt on each of these samples as a coating and the samples were allowed to stand for 48 hours at 50 ⁰ C and at a relative humidity of 80%. Fogging occurred in Sample 2, but not in Sample 1. When an image was copied using a photographic paper comprising Sample 1 and Sample 2 as a support, the copied image was not blurred; the resolving power was good, both supports had the same surface smoothness.

Sample 1 contained 1/3 of titanium oxide compared to Sample 2 but had as photographic paper superior properties compared to sample 2.

Example 2

A polyethylene with a density of 0.916 g / cm 'and a melt index of 5 (NUC-8008, Nippon-Unicar Kabushiki Kaisha) was coated onto a high quality paper with a basis weight of 170 g / m at 340 ° C. in a thickness of 30 μ applied. A polyethylene with a density of 1.03 g / cm and a melt index of 5 (NUC 8055, Nippon Unicar Kabushiki Kaisha) with a content of 14 % titanium dioxide at 280 ^° C. in a thickness of 10 μm was applied to the top of this coating Coating applied. The total thickness was 40 ju. This product was named Sample 3.

A 1.1 mixture of the polyethylene materials indicated above (NUC-8008 and NUC-8055) with a content of 7 % titanium dioxide was applied as a coating to a paper of the same quality at 320 ° C. in a thickness of 40 μm. The product was named Sample 4.

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In both samples 3 and 4, the back side has been described with a polyethylene of a density of 0.916 g / cm above ⁰ C to a thickness of 40 at 32O (NUC 8008): η applied.

The bond strength between the paper surface and the resin layer was made in the same manner as above as described in Example 1 using both samples, and the results shown below were obtained.

Sample 3: No peeling or peeling between papers and polyethylene.

Sample 4: 170 g (peeling or peeling between paper and polyethylene).

,, ff

The properties of the samples in terms of their photographic emulsions were also determined. It was found that the fog density in Sample 3 0.3 and Sample 4 was 1.3; In both samples, the copied image was not blurred and the resolving power was not was good. Both supports had the same surface smoothness.

Sample 3 contained half titanium dioxide as compared with Sample 4. However, it had superior properties as compared to photographic paper Sample 4.

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Claims (3)

2148U6 Claims A waterproof support for a photographic paper formed by extrusion coating of a Resin is made on both surfaces of the paper, characterized in that the resin layer on the surface of the support on which a photographic emulsion is coated should, of an upper layer that comes into contact with the photographic emulsion, and one lower layer that is in contact with the paper, with only the upper layer contains an inorganic pigment. 2. Carrier according to claim 1, characterized in that the upper en and lower resin layers through Coextrusion applied as a coating or coating became. 3. Support according to claim 1 or 2, characterized in that the resin made of polyethylene and the inorganic Pigment consists of titanium dioxide. 2098U / 1535 Blank page