CH633894A5 - Photographic paper - Google Patents

Description

The present invention thus provides a photographic paper comprising an impression on its reverse side, the reflectivity of which is less important than that of the paper in order to present a sharp image, but the reflectivity of which is greater than that of a marking or reference mark. printed, when applied to paper, so as not to be detected by a photoelectric detection device used to cut paper into individual proofs, this paper being characterized in that printing on the reverse side is produced with an ink containing a coloring matter and a white opacifying agent.

The reflective power of photographic paper is normally not less than 90% while the reflective power of a pre-printed marking is usually very lower, and can be as low as about 10%. There is however little adjustment of the reflecting power of the pre-printed marking although it is generally such that it allows the safe use of a printing on the reverse with a reflecting power not less than 50%. Preferably, the reflectivity of the printing on the back is around 70%.

The white opacifying agents used in the context of the invention include titanium dioxide and zinc oxide. Titanium dioxide is preferred, however.

The amount of opacifying agent contained in the ink is generally between 0.1 and 30% (weight (g) / volume (ml)). Preferably less than 10% (g / ml) or even 1% (g / ml) is used.

The color of the coloring matter is not critical and either a fluorescent coloring matter or a colored coloring matter can be used. Particularly advantageous examples are nigrosine G140 (Imperial Chemical Industries) (black), scarlet drimarene R3G (Sandoz) (red) and colanyl violet RL (Hoechst Casella) (violet).

The amount of coloring matter contained in the ink is generally between 0.1 and 10% (weight (g) / volume (ml)). The amount used is preferably less than 5% (g / ml) or even 1% (g / ml).

5

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65

Besides the addition of an opacifying agent, the ink is also formulated in accordance with the standard practices of this technique.

Any photographic paper can be used in the context of the invention. Such paper may or may not contain opacifiers and / or optical agents of gloss.

In producing the reverse print according to the present invention, the ink is printed on the reverse of the photographic paper using conventional printing equipment. Particularly preferred examples of such equipment include etching and flexography, the volume of the ink printed on the paper can be changed using different cell sizes. Since the volume is directly proportional to the surface density of the dry ink layer applied, for a given concentration, the use of gravure or flexography printing equipment allows even a greater degree of adjustment of the reflecting power printing on the back of the paper.

The invention is illustrated by the description of the following examples, referring to the accompanying drawings, in which FIGS. 1 to 6 are diagrams.

Example 1

An ink composition containing the following ingredients was prepared:

50 ml of “Gohsenol” GH20 (6% polyvinyl alcohol; available from Nippon Synthetic Chemical Industriai Company Limited);

50 ml of methanol;

2 drops of "Triton" 770 (available from Rohm &Hass); 8 drops of 3.3% potassium stearate solution;

0.48 g of scarlet Drimarene R3G (Sandoz).

Using a K engraving printing machine (manufactured by RK Chemical Co. Ltd., South View, Royston,

Herts) the resulting ink was printed on the reverse side of an uncoated photographic paper containing titanium dioxide anatase and "Blancophur Bup" (a BAYER gloss agent). A printing plate was used with eight different cell volumes, and prints were obtained on the reverse side of the paper having different surface densities of the dry ink layer applied. For each of the eight reverse prints, the reflectivity, x, was determined using a spectrophoto-meter with automatic filter at a wavelength of 440 nm (Spectromat, model F 53 A, from PRETEMA).

The results were as follows:

number of etching cells / m2 = 1.72.107 m-2 ink density = 9.39.105 gnr3 dry extract = 3.60%

Cell volume Area density of x logiox

(m-3) applied dry ink layer (gm-2)

2.95 xlO-13

0.171

62.5

1.796

2.16X10-13

0.126

69.9

1,844

1.92X10-13

0.112

71.7

1.856

1.20X10-13

0.070

77.0

1.886

0.87 xlO-13

0.051

81.6

1,912

0.44X10-'3

0.026

85.2

1,930

0.27 xlO-13

0.016

88.0

1,944

0.19X10-13

0.011

88.0

1,944

0 (base)

0

88.5

1,947

633,894

A second ink composition was then prepared, identical to the first, but additionally containing 9.4 g of melustral FRN (50% titanium dioxide; which can be obtained from Hoechst).

The ink was printed in exactly the same way as above, and the results were as follows:

number of etching cells / m2 = 1.72.107 m "2 ink density = 9.88.105 g / m3 dry extract = 7.80%

Cell volume Area density of x logiox

(m-3) dry layer of ink applied (gm-2)

Same as 0.390 61.5 1.789

above 0.286 69.5 1.842

0.254 71.7 1.856

0.159 77.6 1.890

0.115 82.5 1.916

0.059 86.8 1.939

0.036 89.3 1.951

0.025 88.1 1.945

0 89.4 1.951

The surface density of the dry ink was plotted in abs cisses and the log x plotted on the ordinate on a graph, x

being the reflecting power of the impression, for an ink with and without the opacifying agent melustral FRN. The results are shown in FIG. 1 in which the line marked P corresponds to the use of the ink with an opacifying agent.

Example 2

An ink composition containing the following ingredients was prepared:

50 ml of "Gohsenol" GH20 50 ml of methanol 2 drops of "Triton" 770

8 drops of 3.3% potassium stearate solution

19 ml of Colonyl Violet RL at 2.5 & (Hoechst Casella).

The resulting ink was printed in exactly the same way as for Example 1, and the results were as follows:

number of etching cells / m2 = 1.72.107 / m2 ink density = 9.60.105 g / m3

dry extract = 2.63%

Cell volume Surface density of x logiox

(m-3) dry layer of ink applied (gm-2)

Same as 0.128 73.3 1.865

above 0.094 77.8 1.841

0.083 79.3 1.899

0.052 82.7 1.918

0.038 85.4 1.931

0.019 87.8 1.943

0.012 89.6 1.952

0.008 90.2 1.955

0 91.1 1.960

3

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25

30

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45

50

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60

65

633,894

4

A second ink composition was then prepared, identical to the first, but additionally containing 9.4 g of melustral FRN (50% titanium dioxide).

The ink was printed in exactly the same manner as in Example 1 and the results were as follows:

number of etching cells / m2 = 1.72.107 / m2 ink density = 1.01.10® g / m3 dry extract = 7.21%

Cell volume

Area density of the

X

logiox

(m "3)

dry layer of ink applied (gm-2)

Same as

0.367

72.2

1.859

above

0.270

77.7

1,890

0.240

79.1

1.898

0.150

82.6

1,917

0.109

85.9

1,934

0.055

88.9

1,949

0.034

90.0

1.954

0.024

90.0

1.954

0

90.6

1.957

The logiox was then plotted, x being the reflecting power of the print, as a function of the surface density of the dry layer applied for an ink with and without the opacifying agent melustral FRN. The results are shown in FIG. 2 with the line marked P corresponding to the use of the ink with an opacifying agent.

Example 3

An ink composition containing the following ingredients was prepared:

50 ml of "Gohsenol" GH20 50 ml of methanol 2 drops of "Triton" 770

8 drops of 3.3% potassium stearate solution 0.4 g of Nigrosine G140 (Imperial Chemical Industries).

The resulting ink was printed in exactly the same way as for Example 1, and the results were as follows:

number of etching cells / m2 = 1.72.107 / m2 ink density = 9.49.105 g / m3 dry extract = 3.00%

The ink was printed in exactly the same way as for Example 1 and the results were as follows:

number of etching cells / m2 = l, 72.107 / m2 s ink density = l, 01.106g / m3 dry extract = 9.50%

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15

Cell volume

Area density of the

X

logiox

(m "3)

dry layer of ink applied (gm ~ 2)

Same as

0.487

60.6

1.782

above

0.357

69.2

1,840

0.318

71.6

1.855

0.198

78.0

1.892

0.144

84.0

1,924

0.074

88.2

1,946

0.045

91.5

1,961

0.032

92.1

1,964

0

92.3

1,965

25

30

The logio x was then plotted on a graph, x being the reflecting power of the impression, as a function of the surface density of the dry layer applied, for an ink with and without opacifying agent melustral FRN. The results are shown in FIG. 3 with the line marked P corresponding to the use of the ink with an opacifying agent.

Example 4

An ink composition containing the following ingredients was prepared:

50 ml of "Gohsenol" GH20 35 50 ml of methanol

2 drops of "Triton" 770

8 drops of 3.3% potassium stearate solution 0.48 g of Drimarène scarlet R3G

40

45

The resulting ink was printed on the back of an uncoated photographic paper containing only titanium dioxide anatase but on the other hand exactly as described in Example 1.

The results were as follows:

number of etching cells / m2 = 1.72.107 / m2 ink density = 9.39.10s g / m3 dry extract = 3.60%

50

Cell volume (m "3)

Surface density of the applied dry ink layer (gm--)

X

logiox

Cell volume (m "3)

Surface density of the applied dry ink layer (gm-2)

X

logiox

Same as

0.144

63.9

1.806

55 Same who

0.171

63.8

1.805

above

0.106

72.2

1.859

above

0.126

70.9

1.851

0.094

73.9

1,869

0.112

72.6

1,861

0.059

79.6

1.901

0.070

78.4

1.894

0.043

84.6

1,927

0.051

82.3

1,915

0.022

87.6

1,942

60

0.026

86.6

1,938

0.013

91.2

1,960

0.016

88.4

1,946

0.009

91.7

1,962

0.011

88.0

1,944

0

92.4

1,966

0

89.8

1.953

65

A second ink composition was then prepared, identical to the first, but additionally containing 9.4 g of melustral FRN (50% titanium dioxide).

A second ink composition was then prepared, identical to the first, but additionally containing 9.4 g of melustral FRN (50% titanium dioxide).

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633894

The ink was printed on the back of an uncoated photographic paper, containing only anatase titanium dioxide, but on the other hand exactly as described in Example 1. The results were as follows:

number of etching cells / m2 = 1.72.107 / m2 ink density = 9.88.105 g / m3 dry extract = 7.80%

Cell volume Surface density of x logiox

(m "3) dry layer of ink applied (gm-2)

Same as 0.390 63.0 1.799

above 0.286 70.8 1.850

0.254 73.4 1.866

0.159 79.6 1.901

0.115 83.7 1.923

0.059 87.9 1.944

0.036 89.3 1.951

0.025 91.4 1.961

0 91.7 1.962

The curve representative of the log x x was then drawn, x being the reflecting power of the impression, as a function of the surface density of the dry layer applied, for an ink with and without the melustral opacifying agent melustral FRN. The results are shown in FIG. 4 with the line marked P corresponding to the use of an ink with an opacifying agent.

Example 5

An ink composition containing the following ingredients was prepared:

50 ml of "Gohsenol" GH20 50 ml of methanol 2 drops of "Triton" 770

8 drops of 3.3% potassium stearate solution

19 ml of 2.5% Colonyl Violet RL.

The resulting ink was printed in exactly the same way as in Example 4 and the results were as follows:

number of etching cells / m2 = 1.72.107 / m2 ink density = 9.60.105 g / m3 dry extract: 2.63%

Cell volume

Area density of the

X

logiox

(m-3)

dry layer of ink applied (gm-2)

Same as

0.128

72.7

1.862

above

0.094

78.3

1.894

0.083

79.4

1,900

0.052

82.7

1,918

0.038

86.1

1,935

0.019

88.9

1,949

0.012

90.3

1.956

0.008

90.5

1.957

0

90.7

1.958

A second ink composition was then prepared, identical to the first, but additionally containing 9.4 g of melustral FRN (50% titanium dioxide).

The ink was printed in exactly the same way as for Example 4 and the results were as follows:

number of etching cells / m2 = 1.72.107 / m2 ink density = 1.01.106g / m3 dry extract = 7.21%

Cell volume

Area density of x

logiox

(m "3)

dry layer of ink applied (gm-2)

Same as

0.367

71.1

1.852

above

0.270

76.8

1.885

0.240

79.2

1,899

0.150

83.3

1,921

0.109

86.4

1,937

0.055

88.8

1,948

0.034

91.3

1,960

0.024

91.7

1,962

0

92.0

1,964

The curve representative of the log x x was then drawn, as a function of the surface density of the dry layer, for an ink with and without the melustral opacifying agent melustral FRN. The results are shown in FIG. 5 with the line marked P corresponding to the use of the ink with an opacifying agent.

Example 6

An ink composition containing the following ingredients was prepared:

50 ml of "Gohsenol" GH20 50 ml of methanol 2 drops of "Triton" 770

8 drops of 3.3% potassium stearate solution

0.40 g of Nigrosine G140.

The resulting ink was printed in exactly the same way as for Example 4 and the results were as follows:

number of etching cells / m2 = 1.72.107 / m2 ink density = 9.49.105 g / m3 dry extract = 3.00%

Cell volume Area density of x logio x

(m "3) dry layer of ink applied (gm" 2)

Same as 0.144

63.8

1.805

above 0.106

70.6

1,849

0.094

72.2

1.859

0.059

78.6

1,895

0.043

83.5

1,922

0.022

86.0

1,934

0.013

88.9

1,949

0.009

90.6

1.957

0

90.8

1.958

A second ink composition was then prepared, identical to the first, but additionally containing 9.4 g of melustral FRN (50% titanium dioxide).

The ink was printed in exactly the same way

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633894

6

as for Example 4 and the results were as follows:

number of etching cells / m2 = 1.72.107 / m2 ink density = 1.01.10® g / m3 dry extract = 9.56%

number of etching cells / m2! ink density = 9.54.105 g / m3 dry extract = 5.49%

l, 72.107 / m2

Cell volume (m "3)

Surface density of the applied dry ink layer (gm-2)

logiox

Same as above

0.265 0.195 0.173 0.108 0.078 0.040 0.024

62.8 70.0 72.3

79.3

84.0

87.1

91.4

1,798 1,845 1,859 1,899 1,924 1,940 1,961

0.017 0

Table (continued)

92.5

92.6

1,966

1,967

Cell volume

Area density of the

X

logiox

(m "3)

dry layer of ink applied (gm-2)

Same as

0.487

61.6

1,790

above

0.357

70.3

1,847

0.318

73.0

1.863

0.199

79.7

1.901

0.144

85.1

1,930

0.073

89.2

1,950

0.045

92.0

1,964

0.032

92.3

1,965

0

90.0

1.954

A third ink composition was then prepared, identical to the first, but additionally containing 2.35 g of zinc oxide.

The ink was printed in exactly the same way as for Example 4 and the results were as follows:

We then drew the curve representative of the log x, as a function of the surface density of the dry layer applied, for an ink without opacifying agent, for an ink with melustral FRN as opacifying agent and for an ink with oxide zinc as an opacifying agent. The results are shown in FIG. 6 with the line marked Pi corresponding to the use of an ink with melustral FRN and the line marked P2 corresponding to the use of an ink with zinc oxide.

As can be seen in each of the graphs, logio x decreases when the surface density increases, but the decrease is considerably less marked when an ink containing an opacifying agent is used in addition to a coloring matter. This is why it is much better to control the logio x and therefore the reflecting power, x. For example, if you want to print on the back of the paper with a reflective power of 70%, then with reference to Figure 6, the surface density of the ink applied, for each of the three black inks, should be :

25

30

a) ink without opacifying agent: 0.108 g / m2

b) ink with zinc oxide: 0.193 g / m2

c) ink with titanium dioxide: 0.357 g / m2.

But if, in practice, these densities deviated from these values, for example 0.05 g / m2 more or less, then the actual surface densities of the applied ink layer and the corresponding reflective powers of the prints on the back of the paper would be respectively:

a) 0.058 to 0.158 gm-2: 81% to 62%

b) 0.143 to 0.243 gm "2: 75% to 65%

c) 0.307 to 0.407 gm-2: 73% to 67%

Thus, by using an ink according to the present invention, the desired reflective power of printing on the reverse side of the photographic paper can be obtained much more easily and much more precisely.

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3 sheets of drawings

Claims (11)

633894 2 1. Photographic paper having on its back a print whose reflectivity is lower than that of paper in order to present a sharp image but whose reflectivity is higher than that of a mark preprinted on paper so that the printing is not detected by a photoelectric detection device of the mark used to cut the paper into individual proofs, characterized in that the printing on the back of the paper is produced with an ink containing a coloring matter and a white opacifying agent. 2. Photographic paper according to claim 1, characterized in that the white opacifying agent is titanium dioxide. 3. Photographic paper according to claim 1, characterized in that the white opacifying agent is zinc oxide. 4. Photographic paper according to one of the preceding claims, characterized in that the amount of opacifying agent contained in the ink is 0.1 to 30% (g / ml). 5. Photographic paper according to claim 4, characterized in that the amount of opacifying agent contained in the ink is 0.1 to 10% (g / ml). 6. Photographic paper according to claim 5, characterized in that the amount of opacifying agent contained in the ink is 0.1 to 1% (g / ml). 7. Photographic paper according to one of the preceding claims, characterized in that the coloring material is nigrosine, scarlet drimarene or violet colanyl. 8. Photographic paper according to one of the preceding claims, characterized in that the amount of coloring matter contained in the ink is 0.1 to 10% (g / ml). 9. Photographic paper according to claim 8, characterized in that the amount of coloring matter contained in the ink is 0.1 to 5% (g / ml). 10. Photographic paper according to claim 9, characterized in that the quantity of coloring matter contained in the ink is 0.1 to 1% (g / ml). 11. A method of manufacturing paper according to one of claims 1 to 10, characterized in that the ink is printed on the paper with a printing device by rotogravure or by flexography. The object of the invention is a photographic paper. In commercial production of photographic prints, long rolls of light-sensitive paper are exposed and processed continuously to produce a succession of photographs arranged along the paper at regular intervals. The paper is then cut into individual photographic prints by a guillotine which is activated when marks or marks preprinted on the paper are detected, using a photoelectric detector device, thanks to their much less reflecting power than the reflective power of unmarked paper. The reflecting power in question here is the ratio between the intensity of the reflected light and the intensity of the incident light expressed as a percentage. Although pre-printed marks can be placed on the front (emulsion side) or on the reverse side of the paper, the present invention relates only to the latter situation. Additionally, the back of photographic paper often has an imprint, such as a firm name or design, which is used by photographic paper manufacturers to identify their products. The reflecting power of the impression thus made on the back of the paper must however be sufficiently greater than that of the pre-printed marks or marks to ensure that the impression on the reverse of the paper is not detected by the device. photoelectric detection, of course having regard to its sensitivity. If the impression of the reverse is detected, then the guillotine is activated with disastrous consequences. To present, in spite of everything, a clear image to the client, the reflecting power of the printing of the reverse side must be lower than the reflecting power of the unmarked paper, and must be much lower for an image with high contrast. However, these requirements are in conflict with those making it possible to avoid unwanted actuation of the guillotine. This is why a compromise is sought in which the reflective power of the impression carried by the back of the paper is high enough to present a sharp image but, moreover, is not too high to prevent the printing on the reverse side is detected by the photoelectric detection device. However, this compromise is difficult to achieve when the printing on the reverse side is produced with an ink containing only a coloring product because, for a small change in the surface density of the dry layer of ink applied, the change in the reflectivity is too big. Thus, the degree of adjustment of the reflecting power of such a print on the reverse side is not sufficient to allow the best compromise to be reached. It has now been found that a greater degree of adjustment of the reflectivity of an impression carried by the back of the paper can be obtained by using an ink which contains an opacifying agent in addition to the coloring product. As a result, the desired reflective power of reverse printing can be obtained much more easily than was previously possible.