DE2044780C3 - Gray paper opaque to actinic light and process for its manufacture - Google Patents

Description

The invention relates to actinic light opaque gray paper for photographic purposes made from fibrous materials containing water-dispersible materials black pigments and / or water-soluble black dyes from 1.3 to 3.8% g / nr. That Paper is mainly used in the silver salt diffusion process. It also relates to a method for Manufacture of such a paper.

Black paper impermeable to actinic light mil contents of black pigments, in particular Carbon black, or black, water-soluble dyes, is known to be used for pholographic Purposes, these papers have the disadvantage that for the production of an opaque, dazzling white Surface multiple white coatings must be applied. Since the weight of these coatings is Relative to the weight of the actual paper is high, these are known to have white coatings provided papers are heavy and have only a low strength.

It is also known e.g. B. according to French patent specification 1431 160, titanium pigments, e.g. titanium dioxide and / or fibrous potassium titanate, and / or finely divided magnesium silicate or aluminum oxide as Use fillers for paper.

Fine combination of these well known types of fillers is not known.

The object of the invention is to improve the known black ones while achieving a higher opacity Papers door photographic purposes by increasing their strength and reducing the proportion of them black pigments and / or dyes.

This object is achieved in that a paper described at the outset is additionally used as titanium pigment 14 to 26 g / m ^{2 of} titanium dioxide and / or fibrous potassium titanate and, based on the weight of the titanium pigment, 1.5 to 15% colloidal particles of hydrous magnesium silicate or hydrous aluminum oxide contains homogeneously distributed.

Papers which contain carbon black as the black pigment are particularly suitable.

In the papers according to the invention up to 10% of the titanium pigment can be replaced by another filler, e.g. B. by sodium silicoaluminate.

The particles of magncsium silicate are preferably about 20 nm in diameter and the particles of the aluminum oxide is preferably about 30 nm in diameter.

If desired, the papers according to the invention can have a white pigmented side on the one hand Have coating. On the other hand, the paper can be rough, pigmented, against water and solvent resistant coating.

A process according to the invention for producing such papers is characterized in that an aqueous pulp of the fibrous materials forming the paper, an aqueous slurry of the titanium pigment and adding an aqueous slurry of the colloidal particles, each individually or in admixture with one another, then adding an aqueous slurry of the black pigment and / or the black dye, adjusts the slurry to an acidic value by adding alum and using it in the usual way / u paper processed and this dries.

Then, on one side of the finished paper, a white pigmented coating and optionally on the other side a rough, pigmented, water and solvent resistant coating be applied.

The papers according to the invention bring progress with them that there is already a single white one on them Coating is sufficient to cover one for duplicating / wcckc required to obtain dazzling white surface layer, while with the known black Papers require at least two such coatings. This is not an easy one Adding the effect of the fillers, but, as tests have shown, to be synergistic Effect that goes far beyond the additive effect of the components.

The examples illustrate some embodiments of the invention. Under "%" is always "weight percent" to understand.

example 1

A 2% aqueous dispersion of hydrous magnesium silicate and an aqueous 50% dispersion of titanium dioxide in rutile form containing 10% sodium silicoaluminal were prepared separately, with a high speed mixer was used. The dispersion of titanium dioxide contained an additional 0.3% sodium hexametaphosphate, based on the weight of the titanium dioxide, to make the dispersion to facilitate the figment particles. The two dispersions were given in the above Sequence of a 3% slurry of sulfite kraft pulp added. This tissue was to one Mahlgraii of about 350 have been refined, with the degree of grinding given in "Canadian degrees of freedom" and was determined by the TAPPf method T-227 m-58. There was 0.5% magnesium silicate and 10% of the Filler pigments added based on the weight of the fibers. Before making the opaque paper 2% cationic starch was added on a Fourdrinier machine to improve filler retention (cf. Pages 688, 689, Vol. 18, Kirk-Othmer, "Encyclopedia of Chemical Technology «) and about 1% water-repellent resin adhesive, both based on the Content of fibers. The pH was adjusted to about 4.5 by adding alum. Then you gave 1.5%, based on the amount of fibers, predispersed carbon black immediately after the addition of the cationic starch added. A paper free from knots and holes was then produced by conventional methods. That Paper was pressed and dried in the usual way. The finished paper was sized with 6% oxidized starch. Calendering was then carried out using a machine in order to obtain a smooth surface for ('ic further coatings to obtain.

The gray paper obtained holds a gap of 0.19 mm, a weight of 170 grams per square meter and contained 15.5 grams of fillers and 2.1 grams of carbon black per square meter. The fillers and the others Additives were practically completely retained by the paper because the white water was in circulation was held. The paper obtained had a uniform gray color and was completely opaque.

Examples II and 111

Following the procedure of Example 1, additional gray papers that looked similar were made. Different from example 1 the dispersions of magnesium silicate and titanium dioxide were mixed, before they were added from the fiber suspension. Further differences emerge from Table 1.

Example Il Example 111 Table I. Example Il Example III

Thickness, millimeters DJS

Weight, g / m 'W> <>

Fillers, g / m '18.4

Ruli. u / m ⁷ 2.36

0.19
Ui5
19.0
2.5

Amount of fuel retained,%, calculated as ash
Opacity of the paper

Completely

93

Completely

Example IV

The 0.19 mm thick gray paper, which was produced according to Example I, was ^{coated on one side in an amount of 50 g / m 2} with an aqueous coating comprising 62 parts of titanium dioxide, 38 parts of barium sulfate and 10.8 parts of gelatin and contained 6 parts of glycerin. The sheet obtained was completely opaque and completely white on the coated side without the gray color of the paper showing through.

^{3 (1} example V

A gray paper according to Example II was in two stages in an amount of 45 g / m * with an aqueous Coated mixture containing 100 parts titanium dioxide, 12 parts c

2; Contained gelatin and 6 parts glycerin. The paper coated in this way was calendered again. On the opposite side of the paper was applied in an amount of 18 g / m ^{2 of} a latex coating, the 55 parts of polyvinylidene chloride, 5 parts of titanium dioxide and

contained in 0.19 part of carbon black.

Example Vl

A gray paper according to Example I was according to Bei-ι game V covered, with the exception that the back cover had a thickness of 0.025 millimeters and consisted of unpigmented high density polyethylene applied by extrusion. Conventional gelatin image-receiving layers were applied to the papers according to Example V and Example VI. The thus obtained Bildcmpf'angs-Papicrc could in combination with an image negative, the one has an opaque coating on the back, can be used successfully in a silver salt diffusion process, 4) with developing outside of the darkroom, i.e. H. in the presence of actinic light. In in each case the photographic prints were satisfactory with no stains or defects by the light falling through.

Example VII

Following the procedure of Example I, a 0.2 mm thick gray paper was made. In this one was the

r> Magnesium silicate replaced by 0.5% hydrous aluminum oxide. It contained 13.5% fillers based on the weight of the fibers. The paper holds a square meter weight of 166 grams and contained 19.5 grams of filler and 2.3 grams of carbon black per square meter. the

hu fillers were retained in an amount of 93%, as emerged from the determination of the ashes. The paper produced in this way was uniformly gray and completely opaque.

'• ι Example VIII

Following the procedure of Example I, a 0.2 mm made of thick gold paper. The 1- "UIIsIoITe consisted

based on 7% titanium dioxide and 7% potassium titanate on the amount of paper fiber. The paper weighed 154 grams per square meter and contained Fs 20 grams of titanium pigments and 2.2 grams of carbon black per square meter. The filler was in a lot held by 93%. The resulting gray paper was completely opaque.

The comparison of the opacities of papers, one of which was manufactured according to Example I and three others were generally made in the same manner, but (A) the hydrous magnesium silicate was omitted or (B) the tilane pigment was omitted was ouer (Ct the soot was omitted, gave the following results:

Paper according to example I:
clear negative, no black spots,

Paper A (no hydrous magnesium silicate.):

many black! lick,

Paper B (no tilan pigment): lots of black spots. Paper C (no soot): negative turned dark.

Claims (8)

Patent claims: 1. For actinic light impermeable gray paper for photographic purposes made of fibers with a content a .. η black pigments dispersible in water and / or water-soluble black dyes of 1.3 to 3.8 g / m ² , characterized in that the Paper also contains 14 to 26 g / m of ^{titanium pigment:} titanium dioxide and / or fibrous potassium titanate and, based on the weight of the titanium pigment, 1.5 to 15% colloidal particles of hydrous magnesium silicate or hydrous aluminum oxide, homogeneously distributed. 2. Paper according to claim 1, characterized in that up to 10% of the titanium pigment by a usual filler are replaced. 3. Paper according to claim 1 or 2, characterized in that that it contains hydrous magnesium silicate with particle diameters of 20 nm. 4. Paper according to claim 1 or 2, characterized in that it is hydrous aluminum oxide with particle diameters of 30 nm. 5. Paper according to one of claims 1 to 4, characterized in that it is on one side has a conventional white pigmented coating. 6. Paper according to claim 5, characterized in that it is on the white pigmented coating opposite side a usual rough, pigmented, resistant to water and solvents has a permanent coating. 7. A method for producing paper according to any one of claims 1 to 4, characterized in that that an aqueous pulp of the fibrous materials forming the paper is an aqueous slurry of the titanium pigment and an aqueous slurry of the colloidal particles, by themselves or in a mixture with one another, added, then an aqueous slurry of the black pigment and / or add the black dye, adjust to a slightly acidic pH value by adding alum and the slurry thus obtained is processed into paper in the usual manner and this is dried. 8. The method according to claim 7 for the production of paper according to claim 5 or 6, characterized in that that one side of the paper Jen white pigmented coating and optionally on the other ropes the rough, pigmented, water and solvent resistant coating brings up.