DE2737742C3 - Filler for the paper industry - Google Patents

Description

The invention relates to a filler for the paper industry.

Fillers are understood to mean materials that are added to the paper stock and used.

It has long been known in paper production that the expensive and relatively difficult to acquire Fibers are replaced by fillers of mineral origin. The filler content of the various Paper types are between 10 and 30%. Another benefit of using fillers in paper production is, among other things, that the finely divided fillers the spaces between the individual Filling in fibers and thereby making the paper surface even and smoother and the transparency of the paper decrease, which is considered a fundamental requirement in printing and writing papers. One disadvantageous phenomenon, however, is that by increasing the amount of filler, the glue content of the Paper declines or more resin is required to achieve the same glue content, that the tear length of the paper also decreases.

The fillers are cared for due to their chemical composition in silicates, sulfates, carbonates and Divide oxides. In the paper industry, that which belongs to the group of silicates is most widespread Kaolin is used. The main cause of the spread of the kaolin is in its relatively inexpensive Texture and in its about 60-70% retention. The retention value indicates how much of the filler mixed in the paper stock remains in the finished product.

The use of chalk, which belongs to the group of carbonates, continues despite its technological point of view favorable properties which in comparison to kaolin about 50-55% retention the limits. The as a filler The chalk used is made from the remains of the naturally occurring, mainly microscopic chalk Algae showing fineness by sludging or by precipitation from calcium chloride solution produced using soda or from calcium hydroxide solution using carbon dioxide. The latter is the so-called precipitated or precipitated calcium carbonate.

Apart from its rather poor retention the natural or precipitated calcium carbonate has the property as a further technological disadvantage on. that it is very sensitive to the aluminum phosphate sulfate used to precipitate the glue When causticizing the waste liquor from sulphate cellulose factories, a significant amount of including potassium, sodium, magnesium, hydroxy! -. Sulphide and silicate ions contaminated, in its main mass calcium carbonate containing blue-green, an unpleasant odor and a basic one Lime sludge exhibiting reaction. Offer to use or regenerate the lime sludge only in a very narrow circle of possibilities. The ίο heavily contaminated and having a high water content Lime sludge therefore ends up in the dump in most of the cellulose factories. The spoil heaps however, on the one hand they take up an extraordinarily large area, on the other hand they lead to a fairly widespread pollution of the environment.

A similar by-product that pollutes the environment the cellulose production is also the residue of the calcium hypochlorite used to bleach the cellulose, its amount through the technical measures implemented in the course of paper production cannot be reduced at all or hardly at all.

The aim of the invention is to use the by-products in the paper industry as fillers.

This object is achieved according to claim 1.
The pH of the suspension is expediently adjusted on the one hand with the aid of different acids in two or more steps, on the other hand with the same acid in several steps.

According to the invention, the lead sludge is advantageously admixed with the lime sludge, the with 100 parts by weight of calcium carried into the suspension in the lime sludge through 25 Parts by weight with the lead sludge introduced calcium is supplemented.

The invention is further described in detail by means of examples.

example 1 Lime sludge became a suspension with a Dry content of 50 g / l made. The pH of the In the first step, the suspension was made using hydrochloric acid

set to 10, in the second step to 5 using hydrogen fluoride.

With the suspension, the pulp for wood-containing machine-smooth printing paper was 20% (on the fiber calculated) treated lime sludge supplied.

The stock was leveled, sheet formation was performed on a laboratory sheet maker carried out. The following values result from the appropriately leveled paper obtained:

Ripping length: 3200 m

Whiteness: 63%

Filler content: 13.0%

The comparison sample made from the same paper stock with 20% kaolin under the same conditions produced, appropriately leveled paper resulted in the following values:

Tear length: 2920 m Whiteness: 62% Filler content: 10.4%

Example 2

A suspension with a dry content of 50 g / l was prepared from lime sludge Suspension was raised to 10 in the first step using sulfamic acid, and in the second step using sulfuric acid set to 9

With the suspension the pulp for wood-containing machine-smooth printing paper 20% (calculated on the fiber) treated lime sludge fed

The stock was leveled, and the sheet formation was carried out on a laboratory sheet-forming apparatus with the obtained leveled accordingly Paper resulted in the following values:

Tear length:
Whiteness:
Filling content:

3150 m

63%

10.6

The comparison sample made from the same paper stock with 20% kaolin under the same conditions produced appropriately leveled paper resulted in the following values:

Tear length:
Whiteness:
Filler content:

2900 m

62%

10.6%

Example 3

A suspension with a dry content of 200 g / l was prepared from lime sludge, and then was so much bleaching sludge was added that to 100 parts by weight of that with the lime sludge in the suspension supplied calcium 1 part by weight calcium supplied with the bleaching sludge was omitted. The pH of the After stirring for 15 minutes, the suspension was adjusted to 9.5 with acetic acid in the first step and to 9.5 in the second Step set to 8 with phosphoric acid

With the suspension, the pulp for half-wood-free office paper was 20% (calculated on the fiber) treated lime sludge supplied.

The stock was leveled and sheet formation was performed on a laboratory sheet forming machine carried out. The following values were obtained for the correspondingly leveled paper obtained:

Average Tear length: 3710m

Whiteness: 72%

Filler content: 11.9%

The comparison sample made from the same paper stock with 20% kaolin under the same conditions produced appropriately leveled paper resulted in the following values:

Average Ripping length: 3440 m

Whiteness: 73%

Filler content: 10.7% Example 4

A suspension with a dry content of 350 g / l was prepared from lime sludge. Then it became like that a lot of bleaching sludge fed to 100 parts by weight of that fed into the suspension with the lime sludge Calcium 25 parts by weight calcium added with bleaching sludge was omitted. The pH of the suspension

was after stirring for 30 minutes in the first with sulfuric acid to 12 pounds and then in the second step with Phosphoric acid adjusted to 12

With the suspension, the pulp for wood-free machine-smooth letterpress paper was 25% (on the fiber calculated) treated lime sludge fed. The paper stock was leveled and the sheet formation was on a paper machine with a working width of 420 cm and a speed of 320 m / min carried out With the correspondingly leveled paper obtained, the following values were obtained:

Average Ripping length: 3210 m

Whiteness: 82%

Filler content: 17.8%

As a comparison sample from the same Piece of paper with 25% kaolin produced according to leveled paper under the same conditions the following values resulted:

Average Tear length

Whiteness:

Filler content:

2960 m

82%

15.6%

Example 5

A suspension with a dry content of 300 g / l was prepared from lime sludge a lot of bleaching sludge fed that to 100 parts by weight of the lime sludge fed into the suspension Calcium 10 parts by weight supplied with bleaching sludge Calcium was omitted. The pH of the suspension was increased after stirring for 25 minutes in the first step adjusted to 8.5 with sulfuric acid and then to 7 in the second step with phosphoric acid.

With the suspension, the pulp for wood-free bond paper was treated 25% (calculated on the fiber) Lime sludge supplied. The paper stock was leveled and the sheet formation on a one working width of 420 cm and a speed of 320 m / min. at the correspondingly leveled paper obtained resulted in the following values:

Average Ripping length: 2950 m

Whiteness: 81%

Filler content 19.6%

The comparison sample made from the same paper stock with 25% kaolin under the same conditions produced appropriately leveled paper resulted in the following values:

Average Ripping length: 2700 m

Whiteness: 80%

■ filler content: 15.0%

On the basis of these examples it can be clearly stated that the one used according to the invention Lime sludge achieves a retention that exceeds the retention of kaolin.

Another significant advantage is that as the amount of filler increases, so do the tear lengths of the finished product do not fall behind at all or only to a very small extent.

Also surprising is the fact that with the used according to the invention, in the initial state far-

bigen, impure lime sludge one among the conventional ones Conditions only through the use of high quality Kaolin achievable white product with the degree of contamination corresponding to the standard specification is obtained.

From the point of view of environmental protection, the fact that the entire amount of lime sludge can be used in paper production.

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Claims (2)

Patent claims: 1. Using the when causticizing Sulphate waste liquors from the production of cel'alose calcium carbonates as fillers for paper production, the calcium carbonate being a maximum of 75% aqueous suspension in the form of the resulting Lime sludge and after adjusting its pH between 5 and 12 with an acid or a Acid mixture is used. 2. Use according to claim 1, wherein the lime sludge suspension is bleaching sludge from cellulose bleaching is added by means of calcium hypochlorite.