FI67357B - ADJUSTMENT BASED BASE SHEET THROUGH SKIVFORM FOR CALCIUM MAGNESIUM CARBONATE SOM FYLLMEDEL OCH / ELLER BESTRYKNINGSPIGMENT - Google Patents

Description

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Use of doped basic calcium-magnesium carbonate, mainly in the form of sheets, as a filler and / or as a pigment for pigmenting

By dividing the separated application 760105 Avdeladd ur patent 760105

It is known that with the pulp in the manufacture of paper there are generally fillers to improve the whiteness, opacity and smoothness of the raw paper. These properties are important because the substrate, especially after satinization, can be heard through when the surface of the raw paper is brushed with pigments.

The use of carbonates in pulp has become increasingly important in recent years, because the advantages of papermaking are much greater in an alkaline environment than in an acidic environment. These are due not only to the service life of this part of the paper mill (corrosion in acid production) and the lower need for grinding energy, but also in particular to the improvement of the properties of papers produced in this way, especially in terms of yellowing tendency, printing properties and resistance to changes. In the case of different grades of paper, the following fillers are particularly suitable: aluminosilicate, magnesium silicate, calcium sulphate, barium sulphate, calcium carbonate (although only for certain grades of paper, such as cigarette papers), titanium dioxide, titanium dioxide barium sulphate mixtures,

In order to improve the printing properties of the paper, the uniformity of its surface, the gloss opacity, the hardness, the varnishability and the uniformity of ink consumption are particularly important.

These properties are achieved or improved when the raw paper is subsequently coated with special white pigments which are applied to the paper as a porridge or suspension in a paper lubricating apparatus.

The pigment is then subjected to the following requirements: high purity, low particle size, high whiteness and opacity, high refractive index, high specific surface area, high Shape ratio, good dispersibility and favorable theological behavior and, of course, good ink acceptability.

These properties are largely achieved by the following pigments and similar combinations, as not all of these substances alone meet the same set requirements: kaolin, calcium carbonate, satin white, titanium dioxide, barium sulfate.

It has now been found that the doped finely divided, mostly wide-form basic calcium carbonate obtained by the process according to the invention is excellently suitable as a pulp additive and / or as a coating pigment in the production of glossy papers.

Particles are obtained, in particular, on papers with a very high gloss after drying, when they are plate-like. In terms of gloss, the quality was better compared to paper coated with kaolin or satin white. The advantage of using precipitated basic calcium magnesium carbonate is still the better opacity of the treated paper and also a higher whiteness.

In a preferred embodiment of the invention, the fineness of calcium magnesium carbonate is 100% 1.

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It is further expedient that the specific surface area of the calcium magnesium carbonate is of the order of 20 m 2 / q.

It is further preferred that the basic calcium magnesium carbonate has a whiteness of> 95%.

In a preferred embodiment, plate-shaped calcium magnesium carbonate particles having a Shape ratio of about one tenth of a power greater than kaolin are used.