FI66192B - FRAMEWORK FOR FOIL FRAMEING FOR PAPER INDUSTRY - Google Patents

Description

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Patent- j · rakiatarihauttu · .... ___________________________, nr ol och ragtaterttyMbMi ™ 3 »-05.öh (32) (33) (31)> ^ * qr Tuotkmn lqW trtoHm 22.08.76 Hungary-Ungern (HU) PA -1257 (71) Papiripari Vallalat, Duna utca * i2, H-1751 Budapest, Hungary-Hungary (HU) (72) BdJa Bozsits, Dunaujväros, Sändor HernSdi, Budapest, Kälmcin Lakner, Budapest, Istvän Lele, Budaörs, Päl Lengyel, Budapest, Jänos Meichl, Dunaujväros, Käroly Strauber, Dunaujväros, Mihäly Sömegi, Dunaujväros,

Arpäd Szalay, Dunaujväros, Elemär Tomcsänyi, Dunaujväros,

Hungary-Hungary (HU) (74) Oy Kolster Ab (5 * 0 Method for the production of fillers for the paper industry -Förfarande för framstälIning av fyllnadsmedel för pappersindustrin

The invention relates to a process for preparing a filler for the paper industry, in which a calcium carbonate suspension containing up to 75% of impurities obtained as a waste product from the production of cellulose using annual plants as raw material is mixed with an acid bleach slurry and adjusted to pH with various organic to 5-12 in two or more steps.

In this context, fillers are understood to mean substances used when added to a paper web.

It has long been known in papermaking to replace expensive and relatively difficult-to-obtain fibrous materials with mineral-based fillers. The filler content of different grades of paper is between 10-30%. In addition, the use of fillers in the manufacture of paper has e.g. the advantage that finely divided fillers fill the spaces between the individual fibers and thus make the paper surface smoother and smoother and reduce the transparency of the paper, which is a fundamental requirement for printing and writing paper grades. One detrimental phenomenon, on the other hand, is that by increasing the filler content, the adhesive content of the paper decreases, and in addition, the breaking length of the paper also decreases.

Based on their chemical composition, fillers tend to be divided into silicates, sulfates, carbonates or oxides. Kaolin, a silicate group, is the most commonly used in the paper industry. The main reason for the prevalence of kaolin can be found in its relatively inexpensive price and its retention of about 60-70 ores. The retention value indicates how much of the filler mixed into the paper web remains in the finished product.

The use of chalk belonging to the group of carbonates, despite its technically advantageous properties, is limited by a retention of about 50-55% compared to kaolin. The chalk used as a filler is made from naturally occurring waste of predominantly microscopic algae by slurrying or precipitating from a calcium chloride solution with soda, or from a calcium hydroxide solution with carbon dioxide. The latter is the so-called. precipitated kaismak carbonate.

Apart from the relatively poor retention, a further technical disadvantage of natural or precipitated calcium carbonate is that it is very sensitive to aluminum sulphate phosphate used as a filler in adhesives.

During the chemical regeneration of sulphate pulp mills, a significant amount of, among other things, potassium, sodium, magnesium, hydroxyl, sulphide and silicate ions as impurities, mainly calcium carbonate-containing blue-green, with an unpleasant odor and a basic reaction. caustic sludge (honey). Opportunities for the utilization or regeneration of causticizing lime sludge can be found in a very narrow area. Causticizing lime sludge, which is rich in impurities and has a high water content, is therefore also landfilled in most pulp mills for this reason. However, landfills require a particularly large area on the one hand, and on the other hand they lead to relatively high levels of environmental pollution.

A similar by-product of cellulose production is the waste of calcium 66192 hypochlorite used for the bleaching of cellulose, the amount of which and the resulting loss of chlorine can hardly be reduced at all or very little by the technical measures taken in papermaking.

The object of the invention is first and foremost to develop a method which uses by-products in the paper industry as a filler.

According to the invention, this object is solved by adjusting the pH of the suspension to between 5 and 12 by means of an organic and / or inorganic acid and / or a mixture thereof.

The pH of the suspension is suitably adjusted, on the one hand, by means of different acids in two or more steps and, on the other hand, by the same acid in several steps.

In the process according to the invention, the causticizing lime slurry is preferably suspended, optionally mixed with hypo-slurry, and the 100 parts by weight of calcium introduced into the suspension with the causticizing lime slurry is supplemented with 25 parts by weight of the calcium introduced with the hypo-slurry.

According to another preferred embodiment of the process according to the invention, natural or precipitated calcium carbonate is suspended and up to 10% of water glass is added to the suspension before the acid treatment.

The invention is further illustrated in detail by the following examples:

Example 1

A suspension with a dry matter content of 50 g / l was prepared from the causticizing lime slurry. The pH of the suspension was adjusted to 10 in the first step with hydrochloric acid and to 5 in the second step with hydrogen fluoride.

According to the suspension, 20% of the treated lime slurry, based on the fibers, was applied to the pulp web of wood-containing machine glossy printing paper.

The pulp was surface glued, sheet formation was performed with a laboratory sheet forming apparatus. The following values were obtained with the corresponding surface-glued paper obtained:

Breaking length: 3200 m degree of whiteness: 63% filler content: 13.0%

Control samples from the same pulp contained 20% kaolin on paper prepared in the same way under the same conditions, the following values were obtained: 4 breaking length 2920 m £ 61 Q 9 degree of whiteness 62% O) s Δ filler content 10.4%

Example 2

A suspension with a dry matter content of 50 g / l was prepared from the causticizing lime slurry. The pH of the suspension was adjusted to 10 in the first step with sulfamic acid and to 9 in the second step with sulfuric acid.

Along with the suspension, 20% of the treated lime slurry, based on the fibers, was fed to a wood-containing machine glossy pulp.

The paper web was surface glued and sheeting was performed with a laboratory sheet forming machine. The surface-glued paper thus obtained had the following values:

Breaking length: 3150 m degree of whiteness: 63% filler content: 10.6%

With a reference sample of the same pulp, with 20% kaolin, on a surface-glued paper prepared under the same conditions, the following values were obtained:

Breaking length: 2900 m degree of whiteness: 62% filler content: 10.6%

Example 3

A suspension with a dry matter content of 200 g / l was prepared from the causticizing lime slurry, and then so much hypo-slurry was added that 1 part by weight of the calcium introduced into the suspension with the causticizing lime slurry became 1 part by weight of the calcium introduced with the hypo-slurry. After stirring for 15 minutes, the pH of the suspension was adjusted to 9.5 in the first step with acetic acid and to 8 in the second step with phosphoric acid.

Along with the suspension, 20% of the treated lime slurry, based on the fibers, was applied to the pulp of the semi-wood-free office paper.

The paper web was surface glued and sheeting was performed with a laboratory sheet forming machine. The following values were obtained with the obtained surface-glued paper: average breaking length: 3710 m degree of whiteness: 72% filler content: 11.9%

With a control sample from the same paper web containing 20% kaolin, the following values were obtained with surface-glued paper prepared under the same conditions: 5 fi 6 Λ Q 9 avg. breaking length 3440 m V O I 7 c degree of whiteness: 73% filler content: 10.7%

Example 4

A suspension with a dry matter content of 350 g / l was prepared from the causticizing lime slurry. So much hypo-slurry was then added that per 100 parts by weight of calcium added to the suspension with the causticizing lime slurry became 25 parts by weight of calcium with the hypo-slurry. After stirring for 30 minutes, the pH of the suspension was adjusted to 12.5 in the first step with sulfuric acid and then to 12 in the second step with phosphoric acid.

Along with the suspension, 25% of the treated lime slurry, based on the fibers, was applied to the pulp (web) of wood-free machine glossy printing paper. The paper pulp was surface glued and the web was formed on a paper machine with a working width of 420 cm and a speed of 320 m / min. The following values were obtained with the corresponding surface-glued paper: degree of whiteness: 3210 m filler content: 82% filler content: 17.8%

As a control, the following values were obtained from the same pulp containing 25% kaolin on the same surface-glued paper produced under the same conditions: average breaking length: 2960 m degree of whiteness: 82% filler content: 15.6%

Example 5

A suspension with a dry matter content of 300 g / l was prepared from the causticizing lime slurry. So much hypo-slurry was then added that per 100 parts by weight of calcium introduced into the suspension with the causticizing lime slurry became 10 parts by weight of calcium introduced with the hypo-slurry. The pH of the suspension was adjusted to 8.5 in the first step of the 5 minute stirring pitch with sulfuric acid and then to 7 in the second step with phosphoric acid.

Along with the suspension, 25% of the treated calcium was introduced into the pulp (web) of wood-free bank paper, calculated from the fibers. The paper pulp was surface glued and the web was formed on a paper machine with a working width of 420 cm and a speed of 320 m / min. The following values were obtained with the corresponding surface-glued paper: 6 66192 average breaking point: 2950 m degree of whiteness: 81% filler content: 19.6%

As a control, the following values were obtained from the same pulp containing 25% kaolin, prepared under the same conditions and surface-glued, respectively: average breaking length: 2700 m degree of whiteness: 80% filler content: 15.0%

Example 6

A suspension with a dry matter content of 50 g / l was prepared from the precipitated calcium carbonate, and 1.5% sulfuric acid and 0.5% phosphoric acid, based on the amount of calcium carbonate, were introduced. This suspension was mixed in an amount of 250 parts by weight per 1000 parts by weight of bleached sulphate cellulose.

The pulp was surface glued and web formation was performed with a Rapid-Köthen web forming machine. The resulting pin-bonded paper had the following values: breaking length: 6000 m filler content: 14.0%

Example 7

Before the acid treatment, 5% of water glass was added to the suspension of Example 6, based on the amount of calcium carbonate. Otherwise, it was resubmitted according to Example 6 and the corresponding surface-glued paper obtained had the following values: breaking point: 5600 m filler content: 16.6%

Example 8

The paper grades prepared according to Examples 6 and 7 were mixed for comparison with a suspension of precipitated calcium carbonate with a dry matter content of 50 g / l, of which 25 parts by weight per 1000 parts by weight of bleached sulphate cellulose.

The paper pulp was surface glued and the web formation was performed with a Rapid-Köthen web forming device. The resulting surface-glued paper had the following values: breaking length: 4660 m filler content: 12.0% 66192 7

Example 9

For comparison purposes, the grades of paper prepared according to Examples 6 and 7 were mixed with the same amount of kaolin paper pulp instead of precipitated calcium carbonate, and the following values were obtained with the surface-glued paper prepared under the conditions of Example 8: breaking length 4860 m that the sensitivity of the causticizing lime slurry or calcium carbonate treated according to the invention to aluminum sulphate was surprisingly reduced compared to the untreated nasal or precipitated calcium carbonate. As a result, its retention achieves and exceeds kaolin retention.

Another significant advantage of the method according to the invention is that as the amount of filler increased, the degree of surface sizing (gluing degree) and the breaking length of the finished product did not decrease at all or only to a very small extent.

It is also surprising that the process according to the invention in the initial state with a colored, impure causticizing lime slurry gives, under previous conditions, only a white product obtainable using very valuable kaolin with a standard degree of impurity.

From the point of view of environmental protection, the fact that the caustic sludge can be used in its entirety for the production of paper is of particular importance.

Claims (8)

66192 8 A process for the preparation of fillers for the paper industry, characterized in that a suspension of impurities containing up to 75% of calcium carbonate obtained as a waste product from the production of cellulose using annual plants as raw material is mixed into a bleaching slurry and the pH of the suspension is adjusted with various organic and / or with inorganic acids to 5-12 in two or more steps. Process according to Claim 1, characterized in that the pH of the suspension is adjusted with different acids in two or more steps. Process according to Claim 1, characterized in that the pH of the suspension is adjusted with the same acid in several steps. Process according to one of Claims 1 to 3, characterized in that the pH of the suspension containing lime slurry is adjusted to 5 to 12. Process according to Claim * 4, characterized in that hypo-slurry is mixed into the suspension. Process according to Claim 5, characterized in that the amount of calcium introduced into the suspension with the causticizing lime slurry, which constitutes 100 parts by weight, is supplemented with at most 25 parts by weight of the calcium introduced with the hypo-slurry. Process according to one of Claims 1 to 3, characterized in that natural or precipitated calcium carbonate is suspended. Process according to Claim 7, characterized in that up to 10% of water glass is added to the suspension before the acid treatment.