DE1517219C - Process for the production of sulphite pulp as well as pulp produced by the process and its use - Google Patents

Description

the most rigorous sizes or dimensions of the suspended material.

In the following description, the method according to the invention is carried out using spruce wood explained as raw material. However, other softwoods as well as hardwood or mixtures are also used Made of softwood and hardwood, suitable for use as a raw material. This applies to 1- and / or multi-year Plant.

IO

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The wood raw material is digested with an aqueous solution that contains sulfite and / or bisulfite ions as well as sodium, potassium, magnesium, calcium or ammonium ions or mixtures of them. In addition, smaller amounts of free SO _{2 can be} present. The pH of the solution at the start of the digestion is 3.0 to 7.0, expediently 3.5 to 6.0 and preferably 3.7 to 5.0. For the digestion, 30 to 200, expediently 40 to 150 and preferably 50 to 100 kg of bound SO ₂ are used per ton of absolutely dry lignocellulose-containing material.

When pumping into the reaction vessel, the cooking liquid can reach a temperature of 40 to 170 ° C, expediently 70 to 150 ° C and preferably 80 to 130 ° C. The cooking liquid can consist of water and the topical chemicals can be freshly prepared, but can also be beneficial in whole or in part from one with the current chemicals, undiluted or diluted waste liquor consist of either directly from a reaction vessel after boiling or during boiling or from a later one Phase of the treatment process that the pulp goes through after cooking can.

The cooking liquid can be pumped in with gas-water discharge and in such a way that the pressure in the reaction vessel is 1 to 12, expediently 2 to 10 and preferably 4 to 8 kg / cm ² . After pumping in the cooking liquid, the so-called pressure impregnation of the cossette material takes place, after which so much cooking liquid is drawn off from the digester that the wood-liquid ratio is in the interval 1: 2.5 to 1: 5.0. The initial temperature in the reaction vessel is, depending on the temperature of the raw material and the pumped-in cooking liquid, in the range 40 to 130 ° C. The contents of the digester are then heated directly or indirectly to the maximum cooking temperature, which is 140 to 190 ° C, preferably 145 to 180 ° C and preferably 150 to ■ 170 ° C can be.

Unlocking is only so far that the chlorine number of the finished pulp 15 to 32, advantageously 19 to 30 and preferably 20 to 28 loading <■ wears, resulting in pulp yields of 65 to 95% (absolutely dry pulp / absolutely dry raw material) . The pulp obtained in this way, when formed into sheets, e.g. B. when feeding in a paper machine, a product with good properties, e.g. B. with good porosity and dimensional stability, especially 'if the pulp has previously been processed and treated according to the invention in the manner indicated below. When using pulp which has been produced and treated according to the invention, a liner with an air permeability of less than 60, expediently less than 40 and preferably less than 30 seconds / 100 ml (Gurley) can thus be obtained. After reaching the desired degree of decomposition, the cell material is blown or poured out of the reaction vessel into a blow tank, a pulp vat or similar arrangement after or without prior leaching.

Treatment of the pulp after the
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The pulp that is opened up and blown out or thrown out in this way becomes defibration or subjected to defibration-refining performed in a known apparatus, e.g. B. in a Bauer, Asplund, Sprout-Waldron or Southerland refiner can be done, the pulp concentration 3 to 45 ° / o, expediently 10 to 40 ° / o, preferably 15 to 30 ° / o, and the temperature to 0 to 100 ° C, suitably 5 to 90 ° C and preferably 10 to 80 ° C can be kept. The defibration resp. Defibration-refining process is directed so that the freeness of the waste liquor-containing or washed Pulp 11 to 22 ° SR, expediently 12 to 19 ° SR and preferably 13 to 18 ° SR.

If the pulp has been defibrated or defibrated too lightly, the freeness of the pulp is below the lower limits of the freeness intervals given above lie what the further processing of the pulp in order to achieve one for the intended Purposes, e.g. B. as a starting material for the production of liner, make a suitable product difficult or impossible. Too high a grind of the Pulp, on the other hand, can be deteriorated in some ways Properties of the end product to be made from the pulp in question, e.g. liner, have as a consequence.

The in this way by defibration or defibration-refining treated pulp is then treated in sieve, sorter, vortex classifier (Centricloaner) and / or processed in other suitable apparatus. In connection with this the pulp becomes the amount of fine material required to achieve the desired end result removes what is different by means of Schibbyesatoren, Vallvik filters, Attis filters, wire screens Type or other appropriate apparatus can happen. The fine material consists of or contains Lignin, lignin derivative, cellulose, hemicellulose, pectin, resin, residual liquor, etc. which is removed according to the invention in order to obtain a pulp suitable for the intended purposes must be, 0.2 to 7%, suitably 0.5 to 5% and preferably 1 to 4% of the pulp on calculated based on the drying weight, depending on the nature and type of the original lignocellulosic Raw material, the degree of digestion during pulp boiling and the intensity of the defibration or defibration-refining. .

The removal of fine material from the pulp serves the purpose of making the pulp more suitable for its processability in the machines that are used for the production of the end product provided according to the invention, e.g. B. Liner, can be used, as well as to improve certain properties of the end product. ■.: · ■ ·· -. ■ ■

After the fines are removed, the pulp is sent to the paper mill, preferably before pumping or the inclusion on the wet machine of a cellulose factory, with finely divided hydrophobic and oleofil material such as ultra-fine particle size magnesium silicates. But others can too Products come into consideration that have the ability to block resin in the pulp, which would otherwise in the processing (conversion) of the pulp and use of the end product cause difficulties can give. The amount of resin blocking material to be added can be 1 to 20 kg per ton absolutely dry cellulose, depending on the ability of the preparation to render the resin harmless do.

The method according to the invention enables the production of a pulp that is suitable for large numbers can be used for various purposes, in particular, but not exclusively, for such Purposes in which sulphate pulp was previously used, for example for liners, whereby the pulp according to the invention can result in a cheaper and in some respects improved end product. in the In the case of liner, the sulfite pulp according to the invention results in a product which, among other things, is stiffer, more water-resistant, is lighter and in some ways stronger than Salfatliner.

The pulp produced according to the invention, which has a chlorine number of 15 to 32, expediently 19 to 30 and preferably 20 to 28, and that after defibrating or defibrating-refining increased to Freeness largely freed from fine material according to the above and the possibly resin-blocking, z. B. hydrophobic and oleofil material was supplied, can in the state in which it is located, used or prior to further conversion into intended end products with other pulp, z. B. sulphate pulp, are mixed.

The following list gives examples of factory manufacturing conditions the invention of bisulfite pulp intended for the manufacture of packaging material Yield.

Cooking liquid

Total SO _L
Bound SO ₂ ,%

₂ ,

pH

Number of kilograms of bound SO ₂ per ton of absolutely dry wood

Temperature when pumping into cooker, ⁰ C

Boiling

Heating time, hours

Printing time, hours

Maximum pressure, kg / cm ²

Maximum temperature, ⁰ C

Gas discharge, hours

Chlorine number of the pulp

Pulp yield, ° / o

Defibration-refining Pulp concentration, ° / o .... Grinding energy, kWh / t pulp., Freeness, ° SR

Removal of fines from the pulp

Loss due to application of the Schibbye method,%> ....

Operational trial I I Π

4.06 2.03 4.7

85.3 80

4.30 0.30 7.0 157 1.30

24.5

71

25th

400

16

1.8

80.0 82

4.00 2.40 5.5 145 0.30

22.6

68

25th

350

15th

Regarding raw material and treatment, the application in cases I and II above was as follows:

Wood water-bearing,

pure bark spruce

Cooker fulfillment according to Svensson with

1 kg of pack steam

Cooking liquid filling ... impregnation

at 5 kg pressure

Cooking while heating

deduction was made at 105 ° C

The food to be cooked was blown to the ladle by 2 kg of pressure. The fiber material was washed and then treated in a Bauer Dofibrator. The pulp was then by means of a centrifugal sieve and Vortex cleaner cleaned.

The test of the pulp in the Valley-Holländer resulted in the following test values:

Operating trial

Meal, minutes

Degree of grinding, ° SR

Volume weight

Tear length, km

Bursting factor

Tear factor

Number of folds

Air permeability according to G ur 1 ey,
Seconds / 100 ml

0
15th

0.485
6.3
48
104
650

0.6

11.5 25

0.590

8.4 62 76 850

4.0 26
45

0.680

9.8
70
61
850

160

14.5 0.475 6.3 47 113 790

0.8

10 25

0.575

8.9 65 86 1300

4.6

23 45

0.650 10.3 75 67 1500

190

The invention is not limited to the above exemplary embodiments or to all of the above data for the The sub-processes included in the procedure are limited, as these depend on the one used Starting material and the end products to be produced in various ways within the scope of the invention can be modified.

Claims (7)

Patent claims: 1. A process for the manufacture of a fiber product such. B. Packaging material, suitable Pulp from lignocellulosic material, by a sulfite process, preferably a bisulfite process, wherein the digested material is controlled defibration and / or defibration-refining is subjected to which, if necessary, ■ to achieve a certain Freeness of the pulp is followed by a grinding process and then a certain one from the pulp Fine material fraction is removed, characterized in that the digestion is driven so far that the chlorine number of the finished pulp is in the range 15 to 32. lies that a freeness of 11 to 22 ° SR is achieved, that the removed fine material fraction 0.2 to 7% of the amount of pulp and that the pulp, if applicable, is a material with the ability to to block resin in the pulp, in an amount of 1 to 20 kg / t absolutely dry Pulp is added. 2. The method according to claim 1, characterized in that the treatment of the digested material is carried out so far that the freeness of the pulp is 12 to 19 ° SR, preferably 13 to 18 ° SR. 3. The method according to any one of the preceding claims, characterized in that from the Pulp fine material in an amount of 0.5. to 5%>, preferably 1 to 4%, e.g. B. 1.5 to 3% of the Pulp, calculated on the dry weight, is removed. 4. The method according to any one of the preceding claims, characterized in that the removal of fine material from the pulp by using Schibbyesatoren, Vallvik filters, Attis filters, wire screens or other suitable apparatus is effected in such a way that certain solid, colloidal, semi-colloidal and dissolved substances in the pulp suspension, z. B. lignin, lignin derivative, cellulose, hemicellulose, pectin, resin, residual liquor, etc., with small Fiber, particle or aggregate sizes in one or more work steps from the pulp be eliminated. 5. The method according to any one of the preceding claims, characterized in that as the The material added to the pulp is a hydrophobic and oleophilic material such as magnesium silicate ultrafine particle size is used and. the absolutely dry pulp in a lot from about 5 to 15 kg per ton is added. 6. pulp, produced according to any one of the preceding claims, characterized by a Chlorine number from 15 to 32, a freeness of 11 to 22 ° SR and a low content of fines. 7. Use of the pulp obtained according to one of claims 1 to 5 for fiber products, such as packaging material, e.g. B. Liner, corrugated paper, cardboard, corrugated cardboard, etc. The present invention relates to a method for producing a fiber product such. B. Packaging material, suitable pulp from lignocellulosic material, by a sulphite process, preferably a bisulfite process, the digested Material is subjected to controlled defibration and / or defibration-refining which, if necessary, is followed by a grinding process to achieve a certain degree of freeness of the pulp, and that a certain amount of fine material is then removed from the pulp, which is thereby is characterized in that the digestion is carried out so far that the chlorine number of the finished pulp in the range 15 to 32 is that a freeness of 11 to 22 ° SR it is achieved that the amount of fine material removed is 0.2 to 7% of the amount of zeI Istoff and that the pulp optionally contains a material with the ability to block resin contained in the pulp, in an amount of 1 to 20 kg / t absolutely dry ao kenem pulp is added. The invention also relates to the pulp produced in this way from lignocellulosic material, characterized with a chlorine number of 15 to 32, a freeness of 11 to 22 ° SR and a low content of fine material, as well as the use of the pulp produced according to the invention for fiber products such as packaging material, e.g. B. Liner, corrugated paper, cardboard, corrugated cardboard, etc. From the Austrian patent specification 203 839 is a process for the production of bleached semi-pulp known from cellulose-containing raw material, which is partially digested by sulfite or bisulfite processes, subsequent mechanical defibration and sorting through a slot screen. In contrast, the method according to the invention is used to digest the lignocellulose-containing material continued until certain values, namely 15 to 32, are reached for the chlorine number. By combining it with a coordinated grinding process and then removing a specific one Fine material fraction of the amount of pulp one obtains a pulp material, its deformation properties are improved on a paper machine. A paper product of great strength and is obtained Stiffness. Thus, the pulp produced according to the invention has the advantage over the known sulfite processes pulps produced have the advantage of a broader field of application. For example Liners for corrugated cardboard are produced, for which sulphate pulp was previously used. The ones from the Products obtained from cellulose produced according to the invention are characterized by a particular brightness and water resistance. It is advantageous to digest the lignocellulose-containing Raw material to carry out only so far that the chlorine number of the finished pulp is im The range is 19 to 30 or 20 to 28, which means pulp yields of 65 to 95% (absolutely dry pulp / absolute dry raw material), whereby the chlorine number and thus the pulp yield, taking into account the nature and type of the starting material to get voted. The amount of fine material removed in the course of the method according to the invention consists of solid, colloidal, semi-colloidal or even dissolved substances that are in the starting material were contained or were formed during the digestion treatment, especially fibers, Particles, aggregates, agglomerates etc. of the lower