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Process for producing tissue paper

a tissue paper and web technology, applied in the direction of non-fibrous pulp addition, pulp liquor regeneration, inorganic base addition, etc., can solve the problems of tissue paper being difficult to dewater during its production, too low dryness during production, and mechanically produced fibrous materials find only limited use, etc., to achieve improved utilization of organic materials, use extraordinarily efficiently, and less chemicals

Inactive Publication Date: 2009-10-29
VOITH PATENT GMBH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0018]The fibers already exhibit high strength values at a freeness which is far lower as compared with fibers used hitherto. The fibrous material according to the invention is already capable of forming good bonds with neighboring fibers at a lower freeness and therefore also with a lower expenditure of refining energy.
[0078]It is viewed as particularly advantageous that, as a result of this management of the filtrate, less fresh water and fewer chemicals are used for the digestion. At the same time, a maximum of dissolved organic material is captured. This improved utilization of the organic materials that have gone into solution also improves the economy of the process according to the invention.

Problems solved by technology

Mechanically produced fibrous materials find only limited use, since here the tendency to yellowing and the poor strength properties of the stocks prevent widespread use.
Furthermore, a high freeness causes a high water retention value for the fibers of the stock suspension, which means that the tissue paper is difficult to dewater during its production.
At high machine speeds, the poor dewatering ability often results in too low a dryness during production.

Method used

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  • Process for producing tissue paper
  • Process for producing tissue paper

Examples

Experimental program
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Effect test

example 1

Coniferous Wood Digestion in the Liquid Phase

[0099]A mixture of birch wood and Douglas fir chips, after steaming (30 minutes in saturated steam at 105° C.), was dosed with a sodium sulfite digestion solution with a liquor ratio of wood:digestion solution of 1:3. The total use of chemicals was less than 15%, based on o.d. wood. The pH at the start of the digestion was adjusted to pH 8.5-9 by adding SO2.

[0100]The birch wood / chips mixture impregnated with chemical solution was heated to 170° C. over a time period of 90 minutes and digested at this maximum temperature over 60 minutes.

[0101]The free-flowing liquid was then removed by centrifuging, collected and analyzed and strengthened in an arrangement for feeding back unused liquid and in this way conditioned for the next digestion.

[0102]The digested chips were defibered. Partial quantities of the fibrous material produced in this way were refined for different times in order to determine the strength at different freenesses. The expe...

example 2

[0109]The fibrous material was produced from birch chips, the pH at the start of the digestion being 9.4.

[0110]In addition to the 15% total chemicals (sulfite and NaOH in the prescribed ratio), 0.1% anthraquinone, based on the quantity of wood used, was added.

[0111]The digestion time was 60 minutes.

[0112]The following values resulted:

Yield (%):81.1Lignin content:22.7Whiteness (% ISO):53.7Tearing length (km):9.6Tear propagation resistance (cN; 100 g / m2):75.0

[0113]As a result of the addition of 0.1% anthraquinone, the digestion time can be reduced from about 180 minutes to 60 minutes under otherwise unchanged digestion conditions. This time gain is valuable, above all because the fibrous material production plants can be dimensioned smaller. Further potential savings reside in the fact that the temperature needed for the digestion has to be maintained over only a very much shorter time period.

[0114]Furthermore, it was determined that, with a decreasing use of overall chemicals to valu...

example 3

Deciduous Wood Digestion in the Liquid Phase

[0115]Eucalyptus chips, after steaming, have a sodium sulfite digestion solution added at a liquor ratio of wood:digestion solution of 1:3. The use of chemicals was 10.5% here (as NaOH) on o.d. chips.

[0116]Over a time period of 90 minutes, the material to be digested was impregnated and the digestion material was heated to the maximum digestion temperature of 170° C. The digestion time was 50 minutes.

[0117]Digestions with eucalyptus wood show that these materials can be produced with a specific energy input for defibering of less than 250 kWh / t.

[0118]The yield in these trials was around 77%, based on the wood mass used. Given an initial freeness of 14°SR, these materials already have a 3.5 km tearing length with a specific weight of 2.05 cm3 / g. In the subsequent bleaching these materials could be bleached to whitenesses of 79.9% ISO.

[0119]Trials have shown that the digestions in the vapor phase exhibit a lower overall time requirement. As ...

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Abstract

The invention relates to a process for producing a tissue web, which is produced from a stock suspension including fibers. In this case, the volume and the tearing length are to be improved with the lowest possible freeness by the stock suspension containing lignocellolosic fibrous material made of wood or annual plants which has a tearing length of more than 6.5 km at 12°SR or a tearing length of more than 8.0 km at 15°SR and a lignin content of at least 15%, based on the oven-dry fibrous material, for coniferous wood in the unbleached state, or a tearing length of more than 4.5 km at 20°SR and a lignin content of at least 12%, based on the oven-dry fibrous material, for deciduous wood in the unbleached state, or a tearing length of more than 3.5 km at 20°SR and a lignin content of at least 10%, based on the oven-dry fibrous material, for annual plants in the unbleached state.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This is a continuation of PCT application No. PCT / EP2007 / 010165, entitled “METHOD FOR THE PRODUCTION OF TISSUE PAPER”, filed Nov. 23, 2007, which is incorporated herein by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The invention relates to a process for producing a tissue web, which is produced from a stock suspension including fibers.[0004]The invention also relates to a process for producing a stock suspension for use in particular for the production of tissue webs.[0005]2. Description of the Related Art[0006]Tissue products are currently mainly produced from fully cellulosic materials, in particular kraft pulps.[0007]Mechanically produced fibrous materials find only limited use, since here the tendency to yellowing and the poor strength properties of the stocks prevent widespread use.[0008]Common mixture ratios between long fiber and short fiber stocks lie in the region of 50:50.[0009]The porosity and the...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): D21C11/00D21H11/00D21C3/02D21C3/06
CPCD21C3/00D21C3/06D21C9/00D21H27/002D21F11/145D21H11/06D21F11/14
Inventor SCHUBERT, HANS-LUDWIGMELTZER, FRANK PETERAALTO, ESA-MATTI
Owner VOITH PATENT GMBH
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