Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C1/00—Pretreatment of the finely-divided materials before digesting
  • D21C1/04—Pretreatment of the finely-divided materials before digesting with acid reacting compounds
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
  • D21B1/00—Fibrous raw materials or their mechanical treatment
  • D21B1/04—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres
  • D21B1/12—Fibrous raw materials or their mechanical treatment by dividing raw materials into small particles, e.g. fibres by wet methods, by the use of steam
  • D21B1/14—Disintegrating in mills
  • D21B1/16—Disintegrating in mills in the presence of chemical agents
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C3/00—Pulping cellulose-containing materials
  • D21C3/04—Pulping cellulose-containing materials with acids, acid salts or acid anhydrides
  • D21C3/06—Pulping cellulose-containing materials with acids, acid salts or acid anhydrides sulfur dioxide; sulfurous acid; bisulfites sulfites

Definitions

• the invention relates to a method according to the preamble of claim 1 for the production of chemo-mechanical and / or chemo-thermo-mechanical wood materials from lignocellulose-containing raw materials, such as wood chips, wood chips, pre-fiberized wood or sawdust.
• a major disadvantage of wood pulp is the low binding capacity of lignin fibers.
• Lignin as a hydrophobic substance has hardly any starting points for hydrogen bonds. Sulphonation of lignin increases its hydrophilicity and thus the binding potential of lignin-containing fibers.
• sulfonation is also the first step in dissolving the lignin, for which a minimum degree of sulfonation must be achieved.
• a solution of sodium sulfite is used for the sulfonation can sulfonate the so-called A x and A y groups of the lignin, of which only between 15 and 30 mol% are present in the lignin (SARydholm, Pulping Processes, Intersciences Publishers, New York, London, Sydney, 1965).
• the lignin is sulfonated by bisulfite ions.
• the rate of sulfonation increases with falling pH.
• lignin condensation occurs, which not only prevent sulfonation, but also cause the lignin to turn dark. Therefore, the reaction temperatures in acid sulfite processes can be limited (maximum 140 ° C), or the pH value and the bisulfite concentration can be increased through increased use of bases.
• PCT-WO 91/19040 teaches that wood can be sulfonated in the gas phase, the sulfonation with SO 2 taking place below 100.degree. Then the wood chips are treated with alkaline solutions and the temperature raised to a maximum of 130 ° C so that no carbohydrate breakdown takes place in the wood. Jayme et al. however, higher temperatures up to 180 ° C apply in the vapor phase digestion. However, you have to increase the amount of base considerably and work with bisulfite solutions with a pH of around 4 (G. Jayme, L. Broschinsky and W. Matzke. Paper 18 , 7, 308-314, 1964. G. Jayme and W. Matzke. Wbl. Textilfabrik. 11/12, 311-314, 1964).
• CH-A-0 430 421 describes a process for the chemical-mechanical production of fibrous materials, in which the lignocellulose-containing material is first soaked with a dilute base solution, then essentially freed from the soaking liquid and introduced into a pressure vessel, the to maintain the pressure steam and such an amount of free SO 2 is supplied that the base is converted into sulfite, bisulfite or mixtures.
• the object of the present invention is now to develop a CTMP production process using acid sulfite solutions which does not require methanol and with minimal amounts of metallic bases.
• the solution according to the invention surprisingly shows that, contrary to the prior art, sulfonation can take place under the selected conditions at high temperatures without lignin condensation reactions, in particular for the whiteness of the lignocellulose-containing raw material to be treated, with reaction products colored dark or black as a result.
• lignocellulose-containing raw materials in particular wood chips
• the wood chips saturated with the impregnation solution are then very quickly heated to a reaction temperature of 130 to 180 ° C. and left at this temperature and a low pH in the gas phase for a period of 2 to 15 minutes.
• the wood chips are removed from the reaction chamber, the excess Sulfur dioxide gas is withdrawn from the reaction material.
• the wood chips are fed to a defibrating device known per se, where the reaction material is defibrated to a preselected degree of fineness by means of preselected specific grinding work from 1,200 to 1,900 kWh / t of pulp.
• a major advantage of pretreatment with acidic sulfite solution is the easy recovery of the SO 2 . Since only small amounts of base are required, the chemical loss is low: After the pretreatment of the wood, the SO 2 can , if it is not chemically bound to the wood or irreversibly bound to the base, in a degassing stage, u. U. can also be recovered with the support of a vacuum.
• the specific grinding energy can be reduced by 40% compared to conventional pretreatment without increasing yield losses.
• the wood chips are impregnated until they are saturated at a temperature ⁇ 100 ° C. This has the advantage that when using solutions with a high sulfur dioxide content, the partial pressure of the SO 2 gas is still relatively low, so that no great demands are placed on the impregnation vessel with regard to pressure resistance.
• the impregnation solution itself contains 1 - 34 g / l base and 20 - 145 g / l SO 2 , depending on the impregnation conditions.
• gaseous SO 2 is additionally pressed into the closed impregnation or reaction vessel.
• a further measure for obtaining the desired degree of impregnation consists in the selection of the dry content of the wood chips before the impregnation, which can be adjusted, for example, by treatment with a screw press to squeeze out water.
• MgO is advantageously used as the base. It is also possible to use other bases based on sodium, calcium or ammonium which are customary in sulfite technology. However, MgO has the advantage of simple handling in the process and a low price.
• the necessary reaction time is not only a function of the amount of chemicals used, but also of the temperature. After the impregnation, the wood chips are transferred directly into the gas phase of the reactor, where the reaction takes place. The desired sulfonation rates are only achieved if the temperature in the reaction area is sufficiently high.
• Spruce wood chips (industrial waste wood) are impregnated with an acidic magnesium bisulfite solution at room temperature. 1,000 g of otro spruce wood chips are used. The solution contains 73.3 g SO 2 / l and 10 g MgO / l. The liquor ratio is 1: 6 after removal the wood chips contain 1.7% MgO / otro wood and 14% SO 2 / otro wood. The dry content is 37%.
• the wood chips are then placed in a reactor. The reactor is then heated to 169 ° C. with steam for 60 s. This temperature is maintained for another 330 s.
• the gas phase arises over a chemical sump containing 7% SO 2 and 1% MgO in 2,300 ml solution, or by introducing 124 g SO 2 and water vapor into the reactor.
• the volume of the gas phase is 35 l.
• the chips are removed from the reactor, suspended in hot water at 80 ° C., filled into a defibrator and defibrated under a steam atmosphere at 130 ° C. and 20% consistency.
• the defibrator coarse material is then ground in a laboratory refiner under atmospheric pressure.
• Spruce wood chips (industrial waste wood) are impregnated as described in Example 1.
• the solution contains 68 g SO 2 / l and 10 g MgO / l.
• the wood chips absorb 1.7% MgO / otro wood and 13% SO 2 / otro wood.
• a treatment is then carried out as described in Example 1.
• the reaction temperature is 157 ° C for 6 minutes.
• 2,040 kWh / t are used to achieve 75 ° SR.
• the tear length is then 6,540 m. To achieve a tearing length of 5,000 m, 1,150 kWh / t grinding energy is used.
• the energy saving compared to conventional CTMP is 39%.
• Spruce wood chips (industrial waste wood) are impregnated as described in Example 1.
• the solution contains 30 g SO 2 / l and 1.7 g MgO / l.
• the wood chips absorb 0.4% MgO / otro wood and 4.1% SO 2 / otro wood.
• the further treatment is carried out as in Example 1.
• the spec. Grinding energy to reach 50 ° SR is 1,189 kWh / t.
• a tear length of 4,800 m is achieved. After pretreatment with 5% Na 2 SO 3 / otro wood, 1,750 kWh / t grinding energy is required to achieve this degree of grinding.
• the tear length is then 4,720 m.
• Spruce wood chips (industrial waste wood) are impregnated as described in Example 1.
• the solution contains 50 g SO 2 / l and 16.7 g MgO / l.
• the wood chips absorb 3.1% MgO / otro wood and 11% SO 2 / otro wood.
• the further treatment is carried out as in Example 1.
• 1,650 kWh / t are used for grinding to 75 ° SR.
• 3,640 kWh / t grinding energy is required. If the same grinding energy is used, 7,170 m tear length is achieved after treatment with 5% Na 2 SO 3 / otro wood.
• Spruce wood chips (industrial waste wood) are impregnated as described in Example 1.
• the solution contains 68 g SO 2 / l and 14 g CaO / l.
• a treatment is then carried out as described in Example 1.
• the reaction temperature is 157 ° C for 6 minutes.
• 1,380 kWh / t are used to achieve 75 ° SR.
• the tear length is then 5,190 m.
• 1,330 kWh / t grinding energy is used. This saves energy compared to conventional CTMP 29%.
• Spruce wood chips (industrial waste wood) are impregnated as described in Example 1.
• the solution contains 68 g SO 2 / l and 20 g NaOH / l.
• a treatment is then carried out as described in Example 1.
• the reaction temperature is 157 ° C for 6 minutes.
• 1,770 kWh / t are used to achieve 75 ° SR.
• the tear length is then 5,810 m.
• 1,350 kWh / t grinding energy is used.
• the energy saving compared to conventional CTMP is 28%.
• the physical properties of the fiber materials obtained are summarized in Table 1.
• the white contents of the acidic magnesium bisulfite substances are 5 to 10% higher than when using Na 2 SO 3 , so that when these substances are used in graphic printing papers, additional bleaching can either be completely omitted or can be carried out with considerably less chemicals can.
• the strength potential of the fiber materials produced by the process according to the invention is close to that of conventional cellulose materials, so that these are at least z. T. can be replaced.
• Table 1 attempt 1 2nd 3rd 4th 5 6 Degree of grinding ° SR (ZMV / 7/61) 75 75 50 92 75 75 Tear length (m) (DIN 53 112) 6,380 6,540 4,800 8,000 5,190 5,810 Gross density g / cm 3 (DIN 53 112) 0.57 0.55 0.46 0.68 0.52 0.52 Tear tear J / m (DIN 53 112) 1.09 1.12 1.22 0.68 1.10 1.08 Light scattering coefficient m 2 / kg (DIN 54 500) 37.1 43.3 47.5 46.1 43.7 43.5 Whiteness% ISO 59.1 60.1 55.4 64.4 61.3 64.1 Yield% 97 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98 98

Landscapes

• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Chemical & Material Sciences (AREA)
• Life Sciences & Earth Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Wood Science & Technology (AREA)
• Chemical & Material Sciences (AREA)
• Paper (AREA)
• Processing Of Solid Wastes (AREA)
• Macromonomer-Based Addition Polymer (AREA)
• Debarking, Splitting, And Disintegration Of Timber (AREA)
• Polysaccharides And Polysaccharide Derivatives (AREA)
• Transition And Organic Metals Composition Catalysts For Addition Polymerization (AREA)

Applications Claiming Priority (3)

Publications (2)

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Cited By (1)

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• 1993
  • 1993-03-11 DE DE4307660A patent/DE4307660C1/de not_active Expired - Fee Related
• 1994
  • 1994-03-03 AT AT94910362T patent/ATE144011T1/de not_active IP Right Cessation
  • 1994-03-03 DK DK94910362.6T patent/DK0688373T3/da active
  • 1994-03-03 JP JP6519572A patent/JPH08507333A/ja active Pending
  • 1994-03-03 CA CA002157886A patent/CA2157886A1/en not_active Abandoned
  • 1994-03-03 WO PCT/EP1994/000627 patent/WO1994020670A1/de active IP Right Grant
  • 1994-03-03 ES ES94910362T patent/ES2095755T3/es not_active Expired - Lifetime
  • 1994-03-03 DE DE59400830T patent/DE59400830D1/de not_active Expired - Fee Related
  • 1994-03-03 EP EP94910362A patent/EP0688373B1/de not_active Expired - Lifetime
• 1995
  • 1995-08-29 NO NO953389A patent/NO953389L/no not_active Application Discontinuation
  • 1995-09-08 FI FI954231A patent/FI954231A0/fi unknown

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