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
  • D21C3/20—Pulping cellulose-containing materials with organic solvents or in solvent environment

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.
• the production of wood pulp in refiners enables better qualities under optimized conditions than in stone grinding production.
• this requires a thermal or thermal and chemical treatment of the wood before defibration.
• the aim of such a pretreatment is to soften the lignin, which reduces the energy required to detach the fibers from the tissue and creates predetermined breaking points in the area of the primary wall and S1.
• the resulting fiber surfaces are high in carbohydrates and therefore have good prerequisites for the formation of hydrogen bonds between the surfaces of these fibers.
• the temperatures to be used in the thermal pretreatment are between 125 and 150 ° C.
• the energy requirement for all refiner pulp processes is significantly higher.
• the defibration energy is deliberately released to the wood layer, which lies directly on the stone surface.
• the energy transfer is less targeted because energy is used to accelerate the material, to rub the wood particles against each other and on the panes, to form the particles and for fluid friction.
• the forces always attack at right angles to the grain where the wood has lower strength. Since the wood chips in the refiner are not always aligned parallel to the centrifugal force with their fiber direction, the energy expenditure for the defibration is higher here.
• the thermal and chemical pretreatment can reduce the energy required to remove the fibers from the wood fabric, but the total energy requirement for producing a more or less largely defibrillated wood pulp does not decrease, since the fiber has become more flexible due to the pretreatment and the influence of the refiner's grinding segments can dodge, so that a more targeted defibrillation is possible, but this requires more loading and relief procedures.
• lignin must be sulfonated to produce high-quality wood pulps. This is usually done by using sodium sulfite in an alkaline medium, since the fibers swell at the same time, which creates favorable conditions for the subsequent defibrillation. As is well known, a sulfonation reaction also takes place in the acidic pH range; the lower the pH, the faster it takes place. Competing condensation reactions of the lignin are also favored by low pH values. Lignosulfonates with a higher degree of sulfonation are water-soluble and therefore reduce the fiber yield. On the other hand, acids attack the carbohydrates, depolymerize them and weaken the fiber structure.
• the lignin can surprisingly be sulfonated without major losses in yield, without the feared condensation reactions occurring.
• the power required during the subsequent defibrillation of the wood can then be reduced to approximately 50% depending on the pretreatment conditions, the resulting wood materials having excellent technological properties.
• the specific grinding work is selected depending on the desired degree of fineness or grinding in a range from 1,200 to 1,900 kWh / t of fiber.
• the use of the acidic system aliphatic alcohol / water / SO2 is not only able to sulfonate lignin, the alcohol taking over the function of the base, but the presence of the alcohol also improves the impregnation, condensation reactions in the lignin are suppressed and resin and fatty acids are dissolved .
• the alcohol also increases the solubility of SO2 in water. This system is effective at temperatures below 100 ° C, but higher temperatures can also be used. It should be noted, however, that the sulfonation is only carried out until the lignin softens at the predetermined breaking points between the primary wall and S1 of the fiber structure. A further sulfonation results from lignin release Loss of yield and fiber damage.
• a major advantage of this type of pretreatment is that the chemicals used can be easily recovered. For alcohol this is possible quantitatively, while with SO2 only the portion that does not react with the wood can be traced. This is a significant advantage compared to base-containing, neutral or alkaline sulfite systems with their complicated recovery.
• the aqueous digestion solution used in the process according to the invention contains 10 to 70 vol.% Aliphatic, water-miscible alcohols and 1.0 to 100.0 g / l sulfur dioxide.
• the pH of the digestion solutions is between 1.0 and 2.0 depending on the SO2 content.
• the wood chips are suspended in this solution, a liquor ratio of 1: 3 to 1: 6 being selected, ie 1 kg of dry wood chips are suspended in 3 to 6 kg of solution.
• the liquor ratio the wood chip moisture measured in each case must be taken into account, which lowers the concentration of the digestion solution.
• the proportion of sulfur dioxide contained in the digestion solution depends on the vol.% Content of alcohol.
• the sulfur dioxide concentration is the extent of the desired lignin sulfonation with regard to the desired yield, the temperature and the time which are chosen for the lignin sulfonation.
• After soaking the wood chips with the digestion solution they are used to initiate the Lignin sulfonation reaction heated to 50-170 ° C. Possibly.
• Excess digestion solution can be removed after soaking, especially if the lignin sulfonation is to take place in the vapor phase.
• the heating can take place indirectly by circulating the digestion solution via a heat exchanger or directly by introducing steam.
• the final temperature is again selected depending on the desired yield, the concentration of the digestion solutions and the digestion time. With short digestion times, a higher final temperature and vice versa can be aimed for. If the final temperature is chosen above 70 ° C, the reaction must be carried out in a pressure-resistant reaction vessel to avoid premature outgassing of the alcohol and sulfur dioxide.
• the existing mixture of alcohol, steam and unused SO2 gas can first be withdrawn and reprocessed, e.g. B. by condensation.
• Alcohol and sulfur dioxide still present in the liquid can also be evaporated and recovered by lowering the pressure or blowing in steam.
• the recovery of the Alcohol and the unused sulfur dioxide can also take place after the defibrating device in a downstream, known heat recovery system with a condensation stage.
• the wood chips are conveyed by known conveying devices of a known defibrating device, such as, for. B. disc refiner, supplied and mechanically defibrated. Possibly. a wood chip washing device can be connected upstream of the defibrating device. A preselected degree of fineness of the chips to be defibrated is achieved by the throughput quantity per unit of time and the work input of the drive of the disc refiner in kwh / t of fiber.
• a known defibrating device such as, for. B. disc refiner
• a wood chip washing device can be connected upstream of the defibrating device.
• a preselected degree of fineness of the chips to be defibrated is achieved by the throughput quantity per unit of time and the work input of the drive of the disc refiner in kwh / t of fiber.
• alcohols whose boiling point is below 100 ° C. under normal pressure. These alcohols include methanol, ethanol, propanol, isopropanol and tertiary butyl alcohol. Because of its high availability and low price, methanol is preferred.
• the mixing ratio between water and alcohol can be varied within wide limits, but the alcohol content between 20 and 50 is preferred Vol.%, In particular between 20 to 40 vol.%, Selected.
• the specified end temperature range during the holding time can be freely selected within the specified limits in coordination with the residence time and the concentration of the digestion solution.
• higher temperatures require additional heat and additional design measures on the reaction vessel because of the pressure that builds up in the process. It is therefore preferred to heat the digestion solution containing the wood chips to a temperature of 80 to 120 ° C. If alcohols with a boiling point close to 100 ° C are used, a temperature of 100 to 120 ° C is selected.
• the holding time at the final temperature influences the degree of yield on the one hand and is determined on the other hand by the volume of the reaction vessel as a function of the mass flow of digestion solution and wood chips to be carried out. For this reason, a holding time at a final temperature of 2 to 120 minutes is preferred, particularly in the case of continuous processes.
• the actual impregnation stage can be preceded by a treatment, the wood chips being pretreated with an alcoholic aqueous solution be that contains a neutral and / or alkaline sodium compound.
• Such sodium compounds can consist of sodium sulfite and / or sodium hydroxide and / or sodium carbonate, the solution preferably containing a concentration of 1 to 10 g / l total alkali, calculated as NaOH.
• the purpose of these sodium compounds is to buffer the organic acids, such as formic and acetic acid, which arise from the wood during the holding time at the final temperature during the actual lignin sulfonation reaction, to avoid lignin condensation due to a low pH value and to promote the swelling of the wood.
• Another advantage of adding the sodium compounds is the maintenance of the white content of the wood chips to be defibrated, especially when sodium sulfite is added.
• Treatment of the wood chips with an aqueous solution containing a sodium compound can also be carried out after the lignin sulfonation reaction in the reaction vessel and after being driven off and drawn off the alcohol and sulfur dioxide gas from the remaining digestion solution.
• the wood chips are first separated from the remaining digestion solution with the aid of devices known per se and then treated with a solution containing the sodium compound at a temperature of 20 to 150 ° C.
• a solution which contains 1 to 10 g / l of sodium sulfite, sodium hydroxide or sodium carbonate, calculated as NaOH, alone or in a mixture is preferred. In this way it is also possible to positively influence the paper technology properties of the wood pulp to be produced.
• the present method can also be applied to mechanically defibrated fibrous materials, such as. B. sauerkraut obtained in the production of wood chips.
• Spruce wood chips are treated at 120 ° C for 10 minutes with a methanol / water mixture of 40:60 vol.%, Which contains 12.5 g / l SO2.
• the liquor ratio is 1: 4.
• the methanol and the unused SO2 are recovered in the gas phase and the wood is defibrated in a refiner.
• the grinding energy requirement is only 1,400 kWh / t, while 25 g / l Na2SO3 pretreated spruce wood chips to achieve the same Freeness 2,500 kWh / t required.
• the energy saving is 44%.
• the fiber has the following technological values: Tear length 3,260 m Tear resistance (Brecht / Imset) 1.04 J / m spec. volume 2.30 cc / g Light scattering coefficient according to SCAN C27: 69 42.5 m2 / kg
• Spruce wood chips are first treated for 15 minutes at 100 ° C with a methanol-water mixture containing 5 g / l Na2SO3, then an aqueous SO2 solution with 50.0 g / l is added and 60 minutes at 100 ° C .
• the liquor ratio is 1: 4 after the addition of the SO2 solution.
• the wood chips are defibrated in the refiner to a freeness of 70 ° SR.
• the energy requirement is 1,850 kWh / t, which means a saving of 26% compared to a standard CTMP.
• the yield is 96%, the fiber has the following technological values at 70 ° SR: Tear length 4,320 m Tear resistance (Brecht / Imset) 1.23 J / m spec. volume 2.22 cc / g Light scattering coefficient according to SCAN C27: 69 46.7 m2 / kg
• a pulp pulped in the refiner without pretreatment to a freeness of 15 ° SR is treated for 10 min at 100 ° C with the methanol / water / SO2 solution described in Example 1 and then further ground in a Jokro mill under standard conditions. 6,750 revolutions were required to achieve a freeness of 70 ° SR.
• the untreated reference material required 15,750 revolutions to achieve a freeness of 63 ° SR.
• Spruce wood chips are treated at 100 ° C for 60 minutes with a methanol-water mixture of 30: 70 vol.%, Which contains 50 g / l SO2. After the treatment time, the methanol and the unused SO2 are recovered and the wood chips are shredded in a refiner. 1,390 kWh / t are required to achieve a freeness of 77 ° SR.
• the yield is 92.0%, the fiber has the following technological values: Tear length 4,070 m Tear resistance (Brecht / Imset) 0.96 J / m spec. Volume 2.03 cc / g Light scattering coefficient according to SCAN C27: 69 39.9 m2 / kg
• Spruce wood chips are steamed for 20 minutes and entered into a methanol / water mixture of 50:50 vol.%, Which contains 100 g / l SO2. After a Impregnation time of 30 minutes, the excess amount of liquid is removed.
• the wood chips impregnated in this way are treated in a defibrator with steam at 150 ° C. for 5 minutes and then defibrated under pressure.
• the grinding energy to achieve a grinding degree of 68 ° SR is 1,510 kWh / t.
• the fiber material produced has the following technological properties: Tear length 4,130 m Tear resistance (Brecht / Imset) 1.02 J / m spec. volume 2.28 cc / g Light scattering coefficient according to SCAN C27: 69 41.5 m2 / kg
• a further digestion experiment was carried out according to the invention with a methanol / SO2 solution which contained 70% by volume of methanol and 23 g / l SO2 at a temperature of 160 ° C. for a digestion period of 8 minutes. These chips were then defibrated in a disc refiner.
• Table 1 example 6 7 8th temperature ° C 160 130 130 Digestion time min 8th 205 300 SO2 use % / l 2.3 5.5 5.5 % / atro 13.9 33.0 33.0 Methanol content Vol .-% 70 50 50 Initial pH - 1.1 1.0 0.9 yield % 92.5 43.5 39.2 Splinter content % 0.8 13.1 10.6 Shatter-free yield % 91.5 April 30 28.6 Whiteness % ISO 61.6 22.8 19.0 Residual lignin content % 22.2 7.8 7.4 Kappa number - 148 51.7 49.5 Intrinsic viscosity dm3 / kg - 544 458 Freeness SR 70 20th 19th Tear length km 4480 1970 1670 Burst resistance kPa - 50 40 Tear resistance cN 70.2 13.2 11.3

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• 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)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Chemical And Physical Treatments For Wood And The Like (AREA)
• Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)
• Catalysts (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Macromonomer-Based Addition Polymer (AREA)

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• 1989
  • 1989-09-28 DE DE3932347A patent/DE3932347A1/de active Granted
• 1990
  • 1990-09-25 CA CA002067129A patent/CA2067129A1/en not_active Abandoned
  • 1990-09-25 AT AT90914536T patent/ATE126294T1/de not_active IP Right Cessation
  • 1990-09-25 DE DE59009516T patent/DE59009516D1/de not_active Expired - Fee Related
  • 1990-09-25 US US07/842,365 patent/US5338405A/en not_active Expired - Fee Related
  • 1990-09-25 EP EP90914536A patent/EP0494214B1/de not_active Expired - Lifetime
  • 1990-09-25 ES ES90914536T patent/ES2076374T3/es not_active Expired - Lifetime
  • 1990-09-25 JP JP2513596A patent/JPH05502480A/ja active Pending
  • 1990-09-25 WO PCT/EP1990/001622 patent/WO1991005102A1/de active IP Right Grant
• 1992
  • 1992-03-23 NO NO921129A patent/NO178467C/no unknown
  • 1992-03-25 FI FI921305A patent/FI921305A0/fi not_active Application Discontinuation

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