EP0239583B2 - Procede de pre-traitement d'une pulpe avec des stabilisateurs et du peroxyde avant le raffinage mecanique - Google Patents

Procede de pre-traitement d'une pulpe avec des stabilisateurs et du peroxyde avant le raffinage mecanique Download PDF

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Publication number
EP0239583B2
EP0239583B2 EP19860905113 EP86905113A EP0239583B2 EP 0239583 B2 EP0239583 B2 EP 0239583B2 EP 19860905113 EP19860905113 EP 19860905113 EP 86905113 A EP86905113 A EP 86905113A EP 0239583 B2 EP0239583 B2 EP 0239583B2
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Prior art keywords
chips
per litre
impregnation solution
impregnation
peroxide
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EP0239583A1 (fr
EP0239583A4 (fr
EP0239583B1 (fr
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Victor Michael Gentile, Jr.
Harry Douglas Wilder
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Kimberly Clark Tissue Co
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Scott Paper Co
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    • 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
    • D21B—FIBROUS RAW MATERIALS OR THEIR MECHANICAL TREATMENT
    • D21B1/00—Fibrous raw materials or their mechanical treatment
    • D21B1/02—Pretreatment of the raw materials by chemical or physical means
    • D21B1/021—Pretreatment of the raw materials by chemical or physical means by chemical means

Definitions

  • Pulping processes can be broadly classified into high yield processes using mechanical fiberizing equipment and low yield processes using chemical reactions to produce individual fibers or pulp from lignocellulosic raw materials, usually wood in chip form.
  • high yield category there are many variations which involve varying combinations of chemical, mechanical, and thermal treatments to effect fiber separation, remove some lignin and other chemical components from the original fibers, or increase the brightness and papermaking strength of the resulting fibers.
  • This invention is directed to the art of high yield pulping in which mechanical treatment either with or without heat is the primary means of fiber separation and mild chemical treatment is used to facilitate fiber separation and to increase the papermaking strength and brightness. The application of heat may be utilized in combination with mechanical and chemical treatments to further assist in fiber separation and to accelerate chemical reactions.
  • the primary goal of this invention is to economically produce pulp in the highest possible yield of the original lignocellulosic raw material by retaining and chemically modifying the lignin in the fibers to obtain the desired papermaking properties.
  • the papermaking strength of high yield pulps can be increased by sulfonation of the lignin, particularly when the wood chips are treated with the sulfonation chemicals (usually sodium sulfite and sodium hydroxide) prior to mechanical defibration (refining).
  • the resulting fibers can also be bleached economically as with alkaline peroxide and/or sodium hydrosulfite to give both improved brightness and papermaking strength.
  • the high levels of sulfonation required for high strength result in pulps which respond less to bleaching than similar non-sulfonated or low-sulfonated pulps, and therefore such highly sulfonated pulps have lower bleached brightnesses although high strength.
  • sulfonation of lignin for increasing papermaking strength of high yield fibers is carboxylation of lignin with oxidants such as alkaline peroxide prior to and/or during defibration.
  • carboxylation results in lignin with carboxylate groups.
  • Both the sulfonate and the carboxylate groups are capable of participating in hydrogen bonding which increases the strength of paper made from such high yield pulps (papermaking strength).
  • alkaline peroxide pretreatment of chips softens the lignocellulosic raw material resulting in easier fiber separation (less energy consumption) and less fines generations (fiber fragmentation) during refining.
  • refiner bleaching with alkaline peroxide can potentially eliminate the need for separate post-refiner bleaching equipment, due to the facts that refiners are excellent mixers of pulp and bleaching agents, and the temperature within the refiner (about 100°C) causes bleaching to occur extremely fast relative to typical post-refiner alkaline peroxide bleaching steps (approximately 50 to 80°C).
  • Peroxide decomposition is hastened by the high temperatures reached in refiners and by metal contaminants, particularly manganese, iron, and copper, which are contained in significant quantities in lignocellulosic raw materials and in lesser quantities in process water. Partial removal or inactivation of such metal contaminants in lignocellulosic raw material can be effected by introducing chelating agents into the wood chips and then removing the chelant-metal complexes. However, the physical entrapment and chemical attraction of such metals by fiber components within the chips make complete removal of the metals impossible.
  • Alkaline peroxide stabilizers like water soluble sodium silicate and magnesium sulfate are often utilized in the peroxide bleaching of high yield pulps to further reduce peroxide decomposition caused by metal contaminants.
  • the silicate forms a flock in alkaline peroxide solutions and this flock attracts and adsorbes the metal ions on its surface thereby reducing their ability to decompose peroxide.
  • Magnesium ions also reduce peroxide decomposition by electronically deactivating the metal ions, thereby reducing the potential of the metal ions to decompose peroxide.
  • the present invention is based in part upon the belief that flocks or precipitates formed by silicates and/or magnesium in alkaline peroxide solutions cannot readily penetrate into the wood chip structures prior to refining due to the large size of the flock relative to the pore size of the wood chips.
  • This belief is reinforced by the fact that such stabilizers effectively stabilize peroxide against decomposition when pulp is being bleached with peroxide but are not as effective when the wood is in chip form rather than pulp.
  • a common method for circumventing the problem of peroxide decomposition in alkaline peroxide bleaching of chips during refining is to add the bleaching agent directly to the refining zone to minimize the contact time between the chip and alkaline peroxide, and in some cases to allow more intimate contact between metal contaminants and silicate and/or magnesium ion stabilizer flocks (See for example, U.S. Patent Nos. 3,023,140-Textor, 3,069,309-Fennell, 4,022,965-Goheen et al., 4,270,976-Sandstrom et al., 4,311,553-Akerlund et al.; Japanese Patent Application No. 80-72091, and Federal Republic of Germany Patent No.2818,320).
  • wood chips have been pretreated by impregnation and/or refining with chelants (U.S. Patent Nos. 3,023,140-Textor, 4,311,553-Akerlund et al., Japanese Patent Application No. 80-72091, and Federal Republic of Germany Patent No. 2818-320) or with sodium silicate (U.S. Patent Nos. 3,069,309-Fennell, 4,311,553-Akerlund et al.), or with magnesium salts (U.S. Patent Nos. 3,023,140-Textor, 3,069,309-Fennell, 4,311,553-Akerlund et al.
  • the present invention is based in part upon the hypothesis that with processes employing alkaline peroxide addition directly into the refiner, the majority of defibration occurs before the alkali and peroxide contact the fibers and have an opportunity to swell and react with the wood, thereby reducing the potential for papermaking strength development, along with requiring more energy for refining and increasing the generation of fines, all of which could be avoided if alkaline peroxide could be inserted and stabilized within the chip prior to defibration.
  • Impregnation of the chips with alkaline peroxide prior to refining has also been practiced (U.S. Patents 4,187,141-Ahrel, and 4,270,976-Sandstrom et al. and Canadian patents 1,078,558, and 1,173,604).
  • the brightness obtained has comparable to that obtainable with post refiner alkaline peroxide bleaching.
  • metal contaminants are not removed or deactivated; rather, peroxide decomposition is reduced by lower alkalinity (U.S. Patent Nos. 4,270,976-Sandstrom et al., Canadian Patent 1,078,558, and 1,173,604) or by minimizing refining temperature (U.S. Patent No.
  • the present invention is based in part upon the theory that refining of chips impregnated with highly alkaline peroxide can be practiced to achieve both high brightness and high strength if stabilizers such as magnesium ions and silicate are impregnated into the chip in a manner to form a stabilizer flock "in situ" within the chip to stabilize alkaline peroxide within the chip.
  • stabilizers such as magnesium ions and silicate are impregnated into the chip in a manner to form a stabilizer flock "in situ" within the chip to stabilize alkaline peroxide within the chip.
  • Chips are usually in the size range of less than 3 centimeters average diameter but can vary.
  • Suitable hardwoods include Aspen, Gmelina, Eucalyptus, Birch, Beech, Oak and Ash.
  • Suitable softwoods include Pine, Spruce, Fir and Hemlock.
  • the lignocellulosic raw material in pieces referred to in the art as chips is treated to produce novel pulp according to the following sequence: (A) chips (usually pretreated with steam and/or washed and soaked in water) are impregnated with a first impregnation solution containing stabilizing chemicals for peroxide (such as a solution containing silicate or magnesium ions and optionally a chelating agent) under conditions of pH, temperature, and concentration for the stabilizing chemicals so that they remain soluble in the first impregnation solution; (B) the chips are impregnated with a second impregnation solution containing the additional stabilizing chemicals, e.g., silicate or magnesium ions, and optionally a chelating agent under conditions of pH, temperature, and concentration so that the chemicals are soluble in the second impregnation solution but precipitate and/or form a flock for stabilizing peroxide when mixed with the first impregnation solution within the chips; and (C) the chips
  • Impregnation steps can be accomplished by squeezing the chips to expel excess liquids and air followed by allowing the chips to expand into the impregnation solution.
  • impregnation solutions of steps B and C can be combined into a single impregnation solution and impregnation step.
  • the alkaline peroxide impregnated chips are then refined in one or more stage(s) under atmospheric pressure or superatmospheric pressure.
  • the refining pressure is usually associated with steam added to or generated within the refining device.
  • the resulting pulp is dewatered and acidified and/or washed to remove bleaching and stabilizing chemicals to result in a novel nonsulfonated pulp having a unique combination of properties including high yield, superior brightness and papermaking strength, and low fines content.
  • Recyclable peroxide is obtained from the dewatering of the pulp after refining and preferably before acidification.
  • the peroxide obtained from the post refiner dewatering step can be reused as makeup in the impregnation step in which peroxide is added to the chips.
  • This invention is useful in producing fibrous pulps from lignocellulosic raw materials such as softwoods, hardwoods, bagasse, straw and other similar fibrous materials which have been chopped or cut into appropriate sized pieces known in the art as chips for pulping into individual fiber form.
  • lignocellulosic raw materials such as softwoods, hardwoods, bagasse, straw and other similar fibrous materials which have been chopped or cut into appropriate sized pieces known in the art as chips for pulping into individual fiber form.
  • the resulting high yield (yield of 80% or higher of the original lignocellulosic raw material) non-sulfonated pulp has properties equal to or superior to sulfonated pulps prepared in similar yields from the same lignocellulosic raw materials. These properties are high brightness and papermaking strength, and low fines content.
  • the process has the advantages of lower capital and operating costs to produce pulps of equal or better quality than comparable sulfonated pulps because of lower equipment costs for the pulping and waste treatment processes, and lower operating costs due to less chemical usage, lower refining energy, and easier treatment of process effluents.
  • all parts are by weight unless otherwise specified, and all parts based upon the weight of chips are based upon the oven-dried weight of the chips.
  • the chips Prior to the first impregnation step, the chips are preferably saturated with water and/or steam to expel any entrapped air in accordance with conventional procedures. Before and as a part of each impregnation step, the chips are preferably squeezed to expel liquid and any remaining air, and then allowed to expand into the impregnation solution so as to absorb the impregnation solution.
  • the quantity of solution absorbed is influenced by the impregnation device and the particular material being impregnated.
  • the level of chemical addition into the chips is primarily controlled by the concentration of the particular chemical in the impregnation solution, the degree of chip compression in the impregnation device, and the density of the chips being treated.
  • the first impregnation solution is an aqueous solution consisting of stabilizers for peroxide and optionally chelating agents and has a pH, temperature, and concentration so as to avoid precipitation of the solutes in the impregnation solution. If a chelating agent is used in the first impregnation solution to effectively chelate deleterious metal ions like manganese, iron, and copper, the pH, temperature and concentration should also be selected to impede the chelant from combining with or inactivating the stabilizers.
  • magnesium sulfate As the stabilizer but other stabilizers can be used such as water soluble magnesium salts (e.g., magnesium chloride, magnesium nitrate, magnesium carbonate, and combinations thereof).
  • chelating agents or complexing agents in the first impregnation solution such as diethylene triaminepentaacetic acid (DTPA), ethylene diaminetetraacetic acid (EDTA), hydroxyethylethylenediamine-triacetic acid (HEEDTA), nitrilotriacetic acid (NTA) sodium tripolyphosphate (STPP) and phosphonic acid derivatives or other similar compounds known in the art for such functionality.
  • DTPA diethylene triaminepentaacetic acid
  • EDTA ethylene diaminetetraacetic acid
  • HEEDTA hydroxyethylethylenediamine-triacetic acid
  • NTA nitrilotriacetic acid
  • STPP sodium tripolyphosphate
  • the concentration of magnesium salt in the impregnation solution is preferably between 0.01 and 2.0 grams per liter calculated based upon the weight of magnesium in the salt so as to result in a magnesium content of the chips equivalent to preferably from 0.001% to 0.2% of the weight of chips.
  • the chelating agent concentration in the impregnation solution should be preferably from 0.01 gram per liter to 20 grams per liter (expressed as 100% chelating agent in the solution) to give preferably 0.001% to 2.0% chelant based on the dry weight of chips but chelant concentration and addition level may extend beyond such ranges depending upon the specific chelating agent and the quantity and species of metal contaminants contained in the chips.
  • the temperature of the first impregnation step is preferably between 15°C and 100°C (100°F and 212°F).
  • the pH is preferably between 5 and 10 with between 7 and 9 being most preferred. Adjustments to the solution pH can be made with any suitable acid or alkaline substance which does not react with peroxide, cause darkening of the chips, or cause any of the components of the impregnation solution to be precipitated or to lose stabilizing and/or chelating ability.
  • the pH, temperature and concentration ranges given above were selected to avoid precipitation of magnesium ions in the solution and to minimize interaction between magnesium ions and the chelant.
  • the second impregnation solution is an aqueous alkaline solution which also consists of stabilizers for peroxide and optionally chelating agents and is at a pH, temperature, and concentration so as to avoid precipitation of the solutes before entering the chip, and if a chelating agent is used, so as to effectively chelate deleterious metal ions like manganese, iron, and copper but not combine with or deactivate the stabilizers to any significant extent.
  • the critical aspect of the present invention is that the pH, temperature, and concentration of the components in the second impregnation solution be suitable for formation of a stabilizer flock after the solution enters the chip and mixes with already impregnated chemicals from the first impregnation step.
  • the second impregnation solution it is preferred to use sodium silicate, especially a 40-42 degrees Baume' sodium silicate solution with 28.7% SiO2 and 8.9% Na2O although there are suitable substitutes recommended by silicate manufacturers for alkaline peroxide bleaching.
  • chelating agents in the second impregnation solution of a type and in concentration and addition level ranges based upon the weight of the chips as described previously for the first impregnation solution.
  • the concentration of sodium silicate in the second impregation solution is preferably between 1.0 and 100 grams per liter calculated and expressed as silicon dioxide (SiO2).
  • the temperature of the second impregnation step is preferably between 15°C and 100°C (60°C and 212°F), and the pH is higher than the pH of the first impregnation solution and preferably greater than 9 with from 9 to 12 being particularly preferred and between 10 and 11 being most preferred. Adjustment to the solution pH can be made in the same manner as described for the first impregnation solution.
  • the second impregnation of the chips results in between 0.1% and 10% silicates, calculated as SiO2 based upon the dry weight of the chips.
  • the third impregnating solution is an aqueous alkaline peroxide solution which may also contain a combination of the stabilizers employed in the first and second impregnation solutions primarily for stabilizing the peroxide outside the chips.
  • the third impregnation solution contains magnesium and silicate stabilizers, and optionally chelating agents of the types and in concentrations and addition levels described for the first and second impregnation solutions.
  • the third impregnation solution contains preferably hydrogen peroxide or any other peroxygen compound suitable for bleaching, in the concentration range of preferably between 10 and 100 grams per liter (calculated and expressed as hydrogen peroxide) to give addition levels of preferably between 0.5% and 10% of the weight of chips expressed as hydrogen peroxide.
  • an alkaline substance preferably sodium hydroxide
  • the temperature of the third impregnating solution is preferably between 15°C and 100°C (60°F and 212°F).
  • the most preferred impregnation sequence is the three stage sequence previously described and presented in more detail in the examples. However, it should be understood that the invention is not limited to the generally described three stage sequence.
  • the second most preferred embodiment of the invention is a two-stage impregnation sequence in which the first impregnation stage is practiced as previously described and the second impregnation solution is combined with the third impregnation solution (alkaline peroxide) and used in a single impregnation step at a pH from 9 to 13. Reversing the solutions by using the first impregnation solution in the second impregnation step and the second impregnation solution in the first impregnation step of the three impregnation sequence described above is the third most preferred embodiment of the invention. That is the first impregnation solution description appearing on pages 9 and 10 becomes the description of the second impregnation solution and likewise the description of the second impregnation solution on pages 11 and 12 becomes the description of the first solution.
  • one component of the stabilizing flock be in the first impregnation solution and a second component be in the second impregnation solution so that the two components form the flock within the chip when the two solutions mix during the second impregnation.
  • the second component it is possible for the second component to be a base that results in a pH adjustment upon mixing of the first and second solutions in the chip to result in the "in situ" formation of the flock or sol.
  • the invention is not limited to the concentration and addition level ranges previously described for stabilizers and chelating agents, since differences in metal contamination levels of lignocellulosic raw materials and/or process water could justify stabilizer or chelating agent usages outside of the specified preferred ranges.
  • the chips are mechanically refined in a suitable defibration apparatus in one or more stages in accordance with conventional processes and equipment.
  • the pressure during refining is optional and can be at atmospheric and/or superatmospheric pressure, depending on the species being pulped and the desired pulp properties.
  • Superatmospheric pressure refining (particularly useful in first stage refining) does increase the papermaking strength, and decrease refining energy and fines generation but at the expense of higher peroxide usage and lower brightness compared to atmospheric refining.
  • the effect on papermaking strength and fines generation is particularly pronounced when the raw material is softwood as contrasted with hardwood.
  • the pulp may be allowed to continue bleaching as long as is practical prior to expelling the impregnation solutions.
  • the amount of peroxide used in the impregnation steps is preferably preselected to result in some residual peroxide remaining after refining in order to maintain high brightness, preferably the refined pulp is concentrated, e.g., by compressing or thickening, to remove residual impregnation solution containing potentially recyclable alkaline peroxide, then cooled and diluted with water, and acidified preferably with sulfur dioxide, sodium bisulfite, or sulfurous acid to a pH between 5.5 and 6.0, and then washed with water.
  • the residual peroxide extracted from the pulp after refining can be recycled as a source of peroxide in one of the impregnation solutions particularly if the process is practiced continuously or in sequential batches.
  • the washed pulp is preferably screened and cleaned to result in a pulp suitable for the production of paper products.
  • Examples A, 1 and 2 compare the process of the present invention with a single step conventional process utilizing the same chemicals. The amount of refining was adjusted to result in comparable pulps in terms of pulp freeness.
  • Example 1 For Example 1, two impregnation stages were used.
  • the first impregnation solution was a water solution containing: 5.28 grams/liter of Epsom salts, technical grade (magnesium sulfate heptahydrate Mg SO4.7H2O); 4.0 grams/liter of the penta sodium salt of diethylenetriamine pentaacetic acid (hereinafter DTPA and available as Versenex 80TM from Dow Chemical Company) and sufficient hydrochloric acid to adjust the pH to 9.0. Impregnation of the Southern pine chips was accomplished with the Sprout-Waldron impregnator as described above.
  • the second impregnation solution was a water solution containing: 5.28 grams/liter of Epsom salt; 0.4 grams/liter of DTPA; 42.2 grams/liter of sodium silicate solution (a 41° Baume' solution, 28.7% SiO2 and 8.9% Na2O, available as type "N" from P Q Corporation hereinafter referred to as "sodium silicate”); 50 grams/liter of sodium hydroxide (technical grade); and 60 grams/liter of hydrogen peroxide (added as a stabilized 50% H2O2 solution, technical grade).
  • the resulting solution had a pH of 11.7.
  • the chips were then refined at atmospheric pressure in a Sprout-Waldron 12'' laboratory refiner. Model 12-1CP.
  • the disk space and the feed rates of chips into the refiner were adjusted as appropriate for the desired energy input.
  • the pulp was dewatered to 25% to 35% consistency, diluted to about 3% consistency, and the pH of the resulting pulp slurry was adjusted to between 5.5 and 6.0 with sulfurous acid (H2SO3) before the pulp properties were tested.
  • the resulting pulp was tested for brightness and the total amount of hydrogen peroxide consumed in the Example was determined. The results are given in Table 1.
  • the dewatering to 25% to 35% consistency after refining yielded recyclable hydrogen peroxide.
  • the "in situ" formation of stabilizing flock within the chips occurred during the second impregnation of the chips as a result of the mixing of the first and second impregnation solutions within the chips.
  • Example 2 the same impregnation procedures, equipment and chemicals in the same total quantities were used as in Example 1.
  • the main change in Example 2 versus Example 1 is that the chemicals were divided among three impregnation steps rather than two.
  • the additional step between the first and second steps of Example 1 impregnates some of the sodium silicate at an alkaline pH into the chips to form a stabilizing flock "in situ" prior to the addition of the hydrogen peroxide in the third impregnation.
  • the first impregnation solution for Example 2 was identical to the first impregnation solution in Example 1 and the same impregnating conditions, procedures and equipment were employed as in Example 1.
  • the second impregnation solution was a water solution containing 21.1 grams/liter of sodium silicate and 0.4 grams/liter of DTPA and had a pH of 10.7.
  • the same conditions, procedures and equipment were employed for impregnation as described in Example 1.
  • the third impregnation solution was an aqueous solution containing 5.28 grams/liter of Epsom salt, 0.4 grams/liter of DTPA, 21.1 grams/liter sodium silicate solution, 50 grams/liter of sodium hydroxide, and 60 grams/liter of hydrogen peroxide (added as a stabilized 50% H2O2 solution) and had a PH of 11.7.
  • Example A the same impregnating procedures, chemicals and equipment were used as in Examples 1 and 2 except that a single impregnation step was used containing all of the chemicals used in Examples 1 and 2 but the amount of DTPA was reduced because the higher levels of DTPA would be incompatible and react with hydrogen peroxide when combined in a single solution.
  • the impregnation solution was a water solution containing 10.56 grams/liter of Epsom salt, 0.4 grams/ liter DTPA, 42.2 grams/liter sodium silicate solution, 50 grams/liter sodium hydroxide and 60 grams/liter of hydrogen peroxide (added as a stabilized 50% H2O2 solution) and had a pH of 11.7.
  • Example 1 After the impregnation step, the chips from Example A were refined, and the resulting pulp was treated after refining as in Example 1. The pulp was then tested for brightness and the amount of hydrogen peroxide consumed was determined. The results are given in Table 1.
  • Example A consumed 7.5% hydrogen peroxide based on the dry weight of the wood chips but achieved a brightness of only 60% (Elrepho brightness).
  • the two-step impregnation sequence of Example 1 achieved a brightness of 72% Elrepho while only consuming 4.2% hydrogen peroxide based on the dry weight of the wood chips.
  • the preferred method of practicing the present invention with the three-step impregnation sequence of Example 2 consumed only 3.7% hydrogen peroxide based on the dry weight of the wood chips and achieved the highest brightness of 75% Elrepho.
  • Pulp produced from Southern Pine chips using the preferred three-stage sequence in Example 3 was compared with pulp produced by a high sulfonation CMP process (Example B) and pulp produced by a low sulfonation CTMP process (Example C) and utilizing commercial scale equipment.
  • Examples 3 B and C the same source of lignocellulosic chips (Southern Pine chips passing through 3/4'' circular screens) was used as in Examples A, 1 and 2. The chips were pretreated with atmospheric steam for 30 minutes. For all the impregnations of Examples 3, B and C, a CE-Bauer Model 560GS Impressafiner was employed. It is a tapered screw press using a 4:1 compression ratio and achieves a temperature of 40°C to 60°C during impregnation due to heat generated within the equipment. After impregnation, the chips were allowed to drain of free impregnation liquor.
  • the chips were refined under a steam pressure of 25 lbs/inch2 gage (psig) in a CE-Bauer Model 418 pressurized refiner and then subjected to secondary refining at atmospheric pressure in a CE-Bauer Model 401 atmospheric refiner.
  • the refiner plate spacing and feed rates were adjusted as appropriate for the energy input and degree of refining which was selected to result in comparable pulps in terms of freeness.
  • the refined pulp was diluted to about 3% consistency, and the pH of the resulting pulp slurry was adjusted to between 5.5 and 6.0 with sodium bisulfite (NaHSO3).
  • the first impregnation solution was a water solution containing 4.4 grams/liter of Epsom salts, 0.4 grams/liter of DTPA and had a pH of 8.3.
  • the second impregnation solution contained 17.6 grams/liter sodium silicate and 0.4 grams/liter DTPA, and had a pH of 10.6.
  • the third impregnation solution contained 4.4 grams/liter of Epsom salt, 0.4 grams/liter of DTPA, 17.6 grams/liter sodium silicate, 60 grams/liter sodium hydroxide and 50 grams/liter hydrogen peroxide and had a pH of 11.9.
  • the pulp produced was tested for brightness, freeness (Canadian standard freeness) and strength (breaking length). Results are given in Table 11.
  • the liquor used in the impregnation stage contained 58 grams/liter SO2 (achieved with a mixture of sodium sulfite and sodium bisulfite) and had a pH of 7.4. A sufficient amount of solution was retained in the chips after impregnation to result in 6.3% SO2 applied to the chips in the Impressafiner. After impregnating the chips, the chips were cooked in a digester with a 4:1 liquor to wood ratio at 160°C for 30 minutes and then the chips were drained of cooking liquor. The cooking liquor contained 59 grams/liter SO2 (achieved with a sodium sulfite and sodium bisulfite mixture) and had a pH of 7.4.
  • Example B The pulp of Example B was tested for brightness, both before (initial) and after bleaching (bleached), freeness and breaking length and the results are given in Table 11. The amount of energy consumed during refining is also given in Table 11.
  • the Southern Pine wood chips were steamed at atmospheric pressure for 30 minutes, and then impregnated using the same equipment as in Example 3 with an impregnation liquor containing 64 grams/ liter sodium sulfite and having a pH of 9.0 to result in 3.8% SO2 applied to the chips based upon the dry weight of chips. After the impregnation step, the chips were subjected to atmospheric steam for 30 minutes. After impregnation and steaming, the chips were refined in the same manner as in Example 3. The resulting refined pulp was then dewatered, washed with water and bleached with peroxide.
  • Bleaching consisted of pretreating the pulp for 10 minutes at 3% consistency with 0.25% DTPA, dewatering the pulp and then bleaching the pulp at 60°C and 12.5% consistency for two hours with a bleaching solution having 4% hydrogen peroxide, 3.5% sodium hydroxide, 4.5% sodium silicate, 0.05% Epsom salt and 0.5% DTPA, (all percentages based upon dry weight of the pulp). After bleaching, the pulp was dewatered, diluted to a 3% consistency and the pH adjusted to 5.5 with sulfurous acid. The pulp was tested for brightness (both before and after bleaching), freeness and breaking length. The amount of energy consumed during refining was also determined. The results are stated in Table 11.
  • the pulp of Example 3 was the brightest and required the lowest refining energy. It was much stronger than the pulp of Example C and brighter and almost as strong as the pulp of Example B.
  • Examples 4, 5 and D were essentially a repeat of Examples 1, 2 and A (present invention compared with a single stage impregnation process using the same chemicals) but with hard wood (Aspen) rather than softwood.
  • the first impregnation solution contained 3.52 grams/liter Epsom salt, 4.0 grams/liter DTPA and had a pH of 9 obtained by adding hydrochloric acid.
  • the second impregnation stage used an aqueous impregnation solution containing 3.52 grams/liter Epsom salt, 0.4 grams/liter DTPA, 28.16 grams/liter sodium silicate, 55 grams/liter sodium hydroxide, 40 grams/liter hydrogen peroxide. It had a pH of 12.5.
  • the chips were refined at atmospheric pressure in the Sprout-Waldron 12'' laboratory refiner Model 12-1CP using the same procedures as in Example 1.
  • the pulp was dewatered to a consistency between 25% and 35%, then diluted to about a 3% consistency and the pH of the resulting pulp slurry adjusted to between 5.5 and 6.0 with sulfurous acid.
  • the pulp was then tested and the results are given in Table 11. The dewatering resulted in a source of hydrogen peroxide that could be recycled by utilizing it in the makeup of an impregnation solution.
  • An aqueous solution identical to the first impregnation solution of Example 4 was used as the first impregnation solution.
  • An aqueous solution containing 14.08 grams/liter sodium silicate and 0.4 grams/ liter DTPA and having a pH of 10.7 was used as the second impregnation solution.
  • the third impregnation solution was an aqueous solution containing 3.52 grams/liter Epsom salt, 0.4 grams/liter DTPA 14.08 grams/liter sodium silicate, 55 grams/liter sodium hydroxide and 40 grams/liter hydrogen peroxide. It had a pH of 12.5.
  • Example D was a single stage impregnation process using the same chemicals, procedures and equipment as in Examples 4 and 5 with the following exception.
  • the impregnation stage of Example D employed an aqueous solution containing 7.04 grams/liter Epsom salt, 0.4 grams/liter DTPA, 28.16 grams/ liter sodium silicate, 55 grams/liter sodium hydroxide and 40 grams/liter hydrogen peroxide.
  • the pH was 12.5.
  • Example D consumed 4.7% peroxide and achieved a brightness of 76%.
  • Example 4 (2 stages) consumed 3.4% peroxide and achieved a brightness of 82% while the preferred three-stage sequence of Example 5 consumed only 1.5% peroxide and achieved the highest brightness (83%).
  • Example E compared the preferred three-stage impregnation process of Example 5 to the CMP process with post refining peroxide bleaching (Example E) and with the high alkaline CTMP process with post refining peroxide bleaching (Example F).
  • Aspen chips of the same type used in Example 5 were presoaked in water for 12 hours under vacuum which is equivalent to the presteaming of Example 5.
  • the soaked chips were then pretreated in a digester by cooking the chips with a 4:1 liquor to chip ratio at 150° for 90 minutes in a sodium sulfite and sodium bisulfite cooking liquor at an initial pH of 6.9 which resulted in 6% SO2 applied based on the dry weight of the chips.
  • the chips were drained of free liquor and refined in the Sprout-Waldron laboratory refiner as in Example 5.
  • the pulp was washed with water and then subjected to a post refining peroxide bleaching step which consisted of pretreating the pulp for 10 minutes at 3% consistency with 0.25% DTPA, dewatering the pulp and then bleaching the pulp at 60°C and at a consistency of 12.5% for 2 hours in a bleaching solution containing 2% hydrogen peroxide, 3.3% sodium hydroxide, 5% sodium silicate, 0.5% DTPA and 0.05% Epsom salt and having a pH of 11.5 (all percentages based upon the dry weight of the pulp). After bleaching, the pulp was dewatered and diluted to 3% consistency and the pH adjusted to 5.5 with sulfurous acid prior to being tested. The test results are given in Table 11.
  • the Aspen chips were presoaked as in Example E and then were impregnated in a digester under vacuum using a 13.3:1 liquor to wood ratio for 12 hours at a temperature of 30°C.
  • the cooking liquor impregnated into the chips was an aqueous solution containing 15 grams/liter of Na2SO3 and 26 grams/liter of sodium hydroxide and had a pH of 12.9. This resulted in 1.7% SO2 and 9.8% sodium hydroxide applied based on the dry weight of the chips.
  • the chips were then drained of excess liquid and steamed at a pressure of 5 lbs/inch2 gauge (psig) for 30 minutes.
  • the treated chips were refined under steam at 15 lbs/ inch2 gauge pressure in the Sprout-Waldron 12" laboratory refiner model 12-1C and then subjected to secondary refining in the same refiner at atmospheric pressure.
  • After refining the pulp was dewatered, washed with water and subjected to hydrogen peroxide bleaching by first pretreating the pulp for 10 minutes at 3% consistency with 0.25% DTPA, dewatering the pulp and then bleaching the pulp at 60°C for 2 hours at 12.5% consistency with a bleaching solution containing 3% hydrogen peroxide, 3.8% sodium hydroxide, 5% sodium silicate, 0.5% DTPA, and 0.05% Epsom salt and having a pH of 11.5 (all percentages based upon the dry weight of the pulp).
  • the bleached pulp was then dewatered, diluted to 3% consistency and the pH adjusted to 5.5 with sulfurous acid.
  • Example 5 The pulp of Example 5 was brighter and stronger than the pulps of Examples E and F and required substantially less energy to refine than in Example E.
  • the preferred three-stage impregnation process of the present invention was compared with CMP pulp subjected to post refining peroxide bleaching and compared with high alkalinity CTMP pulp subjected to post refining peroxide bleaching in order to substantiate the improved process of the present invention and its applicability to a difficult-to-pulp hardwood species (e.g., Eucalyptus Regnans).
  • a difficult-to-pulp hardwood species e.g., Eucalyptus Regnans.
  • Example 5 was repeated using Eucalyptus Regnans chips and with the impregnating solutions given below.
  • the first impregnation solution was an aqueous solution containing 3.96 grams/liter of Epsom salt and 4.0 grams/liter DTPA and having a pH adjusted to 9 with hydrochloric acid.
  • the second impregnation solution was an aqueous solution containing 15.8 grams/liter of sodium silicate, 0.4 grams/liter DTPA and having a pH of 10.7.
  • the third impregnation solution was an aqueous solution containing 3.96 grams/liter of Epsom salt, 15.8 grams/liter of sodium silicate, 0.4 grams/liter DTPA, 60 grams/liter sodium hydroxide and 45 grams/liter hydrogen peroxide, and having a pH of 12.5.
  • Example E for the CMP process was repeated with the same eucalyptus chips as in Example 6.
  • the cooking and bleaching conditions were as follows:
  • a 4:1 liquor to wood ratio was used at 150°C for 90 minutes.
  • the cooking liquor had a pH of 9.5 and resulted in 6% SO2 applied to the chips based upon the dry weight of the chips.
  • the post refining peroxide bleaching process employed a pretreatment with 0.25% DTPA at a 3% consistency for 10 minutes.
  • the pulp was dewatered and then bleached with a bleaching solution containing 5% hydrogen peroxide, 4.8% sodium hydroxide, 5% sodium silicate, 0.5% DTPA, and 0.05% Epsom salt based upon the dry weight of the chips and having a pH of 10.9.
  • Bleaching was at a consistency of 12.5%.
  • Example F was repeated but using the same eucalyptus chips used in Example 6 and with the digestor treatment and bleaching conditions as follows:
  • the digester liquor contained 17 grams/liter of Na2SO3 plus 28 grams/liter sodium hydroxide and had a pH of 12.9 which resulted in 1.3% SO2 and 10.4% sodium hydroxide applied to the chips based upon the dry weight of the chip.
  • the impregnation temperature was 30°C.
  • the chips were drained and steamed for 20 minutes with steam at a pressure of 5 lbs/inch2 gage (saturated).
  • the post refining bleaching solution contained 6% hydrogen peroxide, 5.4% sodium hydroxide, 5% sodium silicate, 0.5% DTPA and 0.05% Epsom salt based upon the dry weight of the chips and had a pH of 11.3.
  • the pulp of Example 6 had the highest brightness and required the least refining energy while its strength was comparable to the high alkalinity CTMP pulp and stronger than the CMP pulp.
  • the preferred three-stage impregnation process of the present invention was compared with conventional CMP with post refiner peroxide bleaching and high alkalinity CTMP with post refiner peroxide bleaching utilizing Gmelina (a tropical hardwood) chips.
  • Examples J, K and 7 were repetitions of Examples E, F and 5 with the exceptions noted below.
  • Gmelina chips of a size that would pass through a 3/4'' circular hole screen were pretreated with atmospheric steam for 20 minutes and then washed with water prior to being utilized in Examples J, K and 7.
  • Example 5 was repeated with the identical solutions as used in Example 5 but with Cmelina chips rather than Eucalyptus chips.
  • Example E was repeated with the same type of Cmelina chips as in Example 7 and with the following cooking and bleaching conditions:
  • the cooking liquor in the digester was used at a ratio of 4:1 of liquor to chips based on the dry weight of the chips. Cooking was done at 150°C for 75 minutes and then the cooked chips were drained of free cooking liquor.
  • the cooking liquor contained 37 grams/liter of Na2SO3 plus 7.4 grams/liter of sodium hydroxide and had a pH of 13. This resulted in 4.4% SO2 and 3% sodium hydroxide applied to the chips based on the dry weight of the chips.
  • the post refining peroxide bleaching treatment was with a solution that contained 5% peroxide, 4.9% sodium hydroxide, 5% sodium silicate, 0.5% DTPA and 0.05% Epsom salt based upon the dry weight of the pulp and had a pH of 11.3.
  • the pulp Prior to bleaching, the pulp was pretreated at a 3% consistency with 0.25% DTPA for 10 minutes and then dewatered. After being bleached for 2 hours at 60°C, the pulp was dewatered and diluted to 3% consistency and the pH was adjusted to 5.5 with sulfurous acid.
  • Example F was repeated except that the chips were of the same type of Gmelina chips as in Example 7 and with cooking and bleaching conditions as stated below.
  • the cooking liquor contained 15 grams/liter of Na2SO3 and 31 grams/liter of sodium hydroxide and had a pH of 13.3.
  • the cooking liquor used in the digester was used at a ratio of 4:1 liquor to chips.
  • the chips were cooked for 45 minutes at 110°C, and then the cooked chips were drained free of cooking liquor. This resulted in 1.3% SO2 and 7.8% of sodium hydroxide applied based upon the dry weight of the chips.
  • the peroxide bleaching solution contained 5% peroxide, 4.9% sodium hydroxide, 5% sodium silicate, 0.5% DTPA, and 0.05% Epsom salt and at a pH of 11.3. Prior to bleaching, the pulp was pretreated at a 3% consistency with 0.25% DTPA for 10 minutes and then dewatered.
  • the pulps of Examples J, K and 7 were tested for brightness, freeness and strength and the energy required to refine the pulps was also determined. The results are given in Table 11.
  • the pulp of Example 7 was the brightest and required the least refining energy although all three pulps had comparable tensile strength.
  • the process of the present invention is capable of achieving novel non-sulfonated pulp having properties not previously achievable.
  • a non-sulfonated pine pulp can be produced for the first time from Pine having a Yield greater than 85%, a Brightness greater than 70% and a Papermaking Strength of at least 3.0 km when refined to a Freeness of 600 ml.
  • a non-sulfonated Aspen pulp can be produced having a Yield greater than 80%, a Brightness greater than 80% and a papermaking Strength of at least 4.0 km when refined to a freeness of 500 ml.
  • a non-sulfonated Eucalyptus pulp can be produced having a Yield greater than 80%, a Brightness greater than 80% and a Papermaking Strength of at least 3.0 km when refined to a Freeness of 500 ml.
  • a non-sulfonated Gmelina pulp can be produced having a Yield greater than 80%, a Brightness greater than 75% and a Papermaking Strength of at least 2.0 km when refined to a Freeness of 500.
  • Hydrogen peroxide usage or consumption (expressed as a weight percent based on the dry weight of the chips) is the quantity of peroxide consumed from the impregnation solution (initial peroxide in the impregnating solution minus final peroxide in the impregnation solution) minus the quantity of residual peroxide in the pulp after refining if followed by a refining step or after bleaching when using post-refiner bleaching.
  • the percentage, peroxide consumed is calculated as being equal to the quantity of peroxide consumed times 100 divided by the dry weight of the chips or pulp fibers.
  • the quantity of peroxide in a solution was determined by iodometric titration using starch as an end point indicator.
  • Brightness is defined as Elrepho brightness in percent units which is determined by using the sample preparation procedure given in the Technical Association of the Pulp and Paper Industry (TAPPI) Official Test Method T218 om-83. The brightness of the sample was measured using TAPPI Provisional Method T525 su-72.
  • Refining energy (net refining energy) is expressed in horse-power days per ton (HPD/T) and is the total energy absorbed by the fibers and associated fluids during refining. It is determined by measuring the total energy input into the refiner during refining and subtracting the energy required to operate the refiner without chips being fed to the refiner (usually referred to as the idle energy required for the refiner). In small laboratory equipment the idle energy is usually significant and must be taken into account. In large industrial equipment it is usually insignificant and not taken into account in determining the energy for refining.
  • HPD/T horse-power days per ton
  • Freeness is defined as Canadian Standard Freeness (CSF) which is measured in milliliters (ml) and was determined in accordance with TAPPI Official Test Method T227 os-58.
  • Papermaking Strength is defined as breaking length (measure of papermaking tensile strength) which is measured in kilometers (km) and is a measure of the maximum length of a paper sheet that is self supporting.
  • the paper sheet was prepared using the sample preparation procedure given in TAPPI Official Test Method T205 om-81, the test specimen of the paper sheet was prepared using the sample preparation procedure given in TAPPI Official Test Method T220 om-83, and the strength measurement of the test specimen was determined by using the procedure given in TAPPI Official Test Method T494 om-81.
  • Yield is a percentage and is defined as the dry weight of pulp times 100 divided by the dry weight of the chips from which the pulp was made.

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Abstract

Production d'un nouveau type de pulpe, principalement de pulpe de bois, à partir de copeaux en utilisant un prétraitement avec des stabilisateurs et un peroxyde alkalin avant la fibrillation mécanique (raffinage) pour accroître la blancheur des fibres résultantes et la résistance du papier pouvant être obtenue avec les fibres. Le nouvel aspect du prétraitement avant le raffinage est qu'il provoque la formation in situ à l'intérieur des copeaux d'une floculation ou d'un sol stabilisateurs.

Claims (39)

  1. Procédé de fabrication de pâte à haut rendement pour matériau lignocellulosique sous forme de copeaux, comprenant, dans la séquence suivante :
    (a) l'imprégnation des copeaux avec une première solution d'imprégnation contenant des produits chimiques stabilisants pour peroxyde dans des conditions de pH, température et concentration des produits chimiques stabilisants telles que ceux-ci sont solubles dans la première solution d'imprégnation ;
    (b) l'imprégnation des copeaux avec une seconde solution d'imprégnation contenant des produits chimiques stabilisants pour peroxyde dans des conditions de pH, température et concentration préétablies pour donner :
    (i) des conditions dans lesquelles les produits chimiques dans ladite seconde solution d'imprégnation sont solubles dans la seconde solution d'imprégnation ; et
    (ii) lorsque ladite seconde solution est mélangée avec la première solution d'imprégnation dans les copeaux, le mélange donne des conditions dans lesquelles un ou plusieurs des produits chimiques stabilisants dans la combinaison de la première solution d'imprégnation et de la seconde précipite(nt) ou forme(nt) une masse floconneuse pour la stabilisation du peroxyde à l'intérieur des copeaux ;
    (c) l'imprégnation des copeaux avec une troisième solution d'imprégnation contenant un peroxyde alcalin ; et
    (d) le raffinage mécanique des copeaux imprégnés de peroxyde alcalin, pour la production d'une pâte.
  2. Procédé selon la revendication 1, dans lequel la première solution d'imprégnation contient un sel de magnésium soluble dans l'eau et a un pH compris entre 5 et 10, et la seconde solution d'imprégnation contient du silicate de sodium et a un pH qui est plus élevé que le pH de la première solution d'imprégnation et se situe entre 9 et 12.
  3. Procédé de fabrication de pâte à haut rendement pour matériau lignocellulosique sous forme de copeaux, comprenant, dans la séquence suivante :
    (a) l'imprégnation des copeaux avec une première solution d'imprégnation contenant des produits chimiques stabilisants pour peroxyde dans des conditions telles que pH, température et concentration des produits chimiques stabilisants, que ceux-ci sont solubles dans la première solution d'imprégnation ;
    (b) l'imprégnation des copeaux avec une seconde solution d'imprégnation contenant un peroxyde alcalin et des produits chimiques stabilisants pour peroxyde, dans des conditions de pH, température et concentration préétablies pour donner :
    (i) des conditions dans lesquelles les produits chimiques dans ladite seconde solution d'imprégnation sont solubles dans la seconde solution d'imprégnation, et
    (ii) lorsque ladite seconde solution est mélangée avec la première solution d'imprégnation dans les copeaux, le mélange donne des conditions dans lesquelles un ou plusieurs des produits chimiques stabilisants dans la combinaison de la première solution d'imprégnation et de la seconde précite(nt) ou forme(nt) une masse floconneuse pour la stabilisation du peroxyde dans les copeaux ; et
    (c) le raffinage mécanique des copeaux imprégnés de peroxyde alcalin pour la production d'une pâte.
  4. Procédé selon la revendication 3, dans lequel la première solution d'imprégnation contenant un sel de magnésium soluble dans l'eau et a un pH compris entre 5 et 10, et la seconde solution d'imprégnation contient du silicate de sodium et a un pH qui est plus élevé que le pH de la première solution d'imprégnation et se situe entre 9 et 13.
  5. Procédé selon la revendication 1, dans lequel :
    (a) la première solution d'imprégnation a un pH qui est plus élevé que le pH de la seconde solution d'imprégnation et se situe entre 9 et 12, et contient :
    (i) du silicate de sodium à une concentration comprise entre 1,0 g par litre et 100 g par litre de silicate calculés et exprimés en dioxyde de silicium, et
    (ii) un agent chélateur pour ions métalliques, choisi parmi l'acide diéthylène-triaminepenta-acétique, l'acide éthylènediaminetétraacétique, l'acide hydroxyéthyléthylènediaminetriacétique, l'acide nitrilotriacétique, le tripolyphosphate de sodium ou des dérivés d'acide phosphonique, à une concentration d'agent chélateur dans la première solution d'imprégnation allant de 0,01 g par litre à 20 g par litre ;
    (b) la seconde solution d'imprégnation a un pH compris entre 5 et 10 et contient :
    (i) des sels de magnésium solubles dans l'eau, à une concentration comprise entre 0,01 g par litre et 2,0 g par litre, exprimée en poids de magnésium, et
    (II) un agent chélateur pour contaminants métalliques, choisi par l'acide diéthylènetriaminepentaacétique, l'acide éthylènediaminetétraacétique, l'acide hydroxyéthyléthylènediaminetriacétique, l'acide nitrilotriacétique, le tripolyphosphate de sodium ou des dérivés d'acide phosphonique, à une concentration d'agent chélateur allant de 0,01 g par litre à 20 g par litre;
    (c) les imprégnations des copeaux sont effectuées à une température comprise entre 15 et 100°C ;
    (d) la seconde imprégnation a pour résultat une teneur des copeaux en magnésium comprise entre 0,001 % et 0,2 %, par rapport au poids sec des copeaux, et une teneur des copeaux en agent chélateur allant de 0,01 % à 2 % d'agent chélateur par rapport au poids sec des copeaux ;
    (e) la première imprégnation des copeaux a pour résultat une teneur en agent chélateur allant de 0,01 % à 2,0 % par rapport au poids sec des copeaux, et une teneur en silicates comprise entre 0,1 % et 10 %, par rapport au poids sec des copeaux ;
    (f) la troisième solution d'imprégnation a un pH compris entre 11 et 13 et contient du peroxyde à une concentration allant de 10 g par litre à 100 g par litre, exprimée en peroxyde d'hydrogène, pour donner une teneur des copeaux en peroxyde comprise entre 0,5 et 10 %, exprimée en peroxyde d'hydrogène et par rapport au poids sec des copeaux, et stabilise le peroxyde.
  6. Procédé selon la revendication 2 ou 4, dans lequel la première solution d'imprégnation a une teneur en dits sels de magnésium comprise entre 0,01 g par litre et 2,0 g par litre, exprimée en poids de magnésium.
  7. Procédé selon la revendication 6, dans lequel les imprégnations des copeaux sont effectuées à une température comprise entre 15 et 100°C.
  8. Procédé selon la revendication 6, dans lequel la première imprégnation des copeaux a pour résultat une teneur des copeaux en magnésium comprise entre 0,001 % et 0,2 %, par rapport au poids sec des copeaux.
  9. Procédé selon la revendication 8, dans lequel la première solution d'imprégnation contient un agent chélateur à une concentration allant de 0,01 g par litre à 20 g par litre.
  10. Procédé selon la revendication 9, dans lequel l'agent chélateur est choisi parmi l'acide diéthylène-triaminepentaacétique, l'acide éthylènediaminetétraacétique, l'acide hydroxyéthyléthylènediaminetriacétique, l'acide nitrilotriacétique, le tripolyphosphate de sodium ou des dérivés d'acide phosphonique.
  11. Procédé selon la revendication 9, dans lequel la première imprégnation des copeaux a pour résultat une teneur des copeaux en agent chélateur allant de 0,001 % à 2,0 %, par rapport au poids sec des copeaux.
  12. Procédé selon la revendication 2, dans lequel la seconde solution d'imprégnation a un pH compris entre 10 et 11, et contient suffisamment de silicate de sodium pour donner une concentration de silicates comprise entre 1,0 g par litre et 100 g par litre, exprimée en dioxyde de silicium.
  13. Procédé selon la revendication 4, dans lequel la seconde solution d'imprégnation contient un sel de magnésium et une quantité suffisante de silicate de sodium pour donner une concentration de silicates comprise entre 1,0 g par litre et 100 g par litre, exprimée en dioxyde de silicium, et contient du peroxyde à une concentration de 10 g par litre à 100 g par litre, calculée en peroxyde d'hydrogène.
  14. Procédé selon la revendication 12 ou 13, dans lequel la dite seconde solution d'imprégnation contient un agent chélateur à une concentration de 0,01 g par litre à 20 g par litre.
  15. Procédé selon la revendication 14, dans lequel ledit agent chélateur est choisi parmi l'acide diéthylènetriaminepentaacétique, l'acide éthylènediaminetétraacétique, l'acide hydroxyéthyléthylènediaminetriacétique, l'acide nitrilotriacétique, le tripolyphosphate de sodium ou des drivés d'acide phosphonique.
  16. Procédé selon la revendication 14, dans lequel la seconde imprégnation des copeaux a pour résultat une teneur des copeaux en agent chélateur allant de 0,001 % à 2,0 %, par rapport au poids sec des copeaux.
  17. Procédé selon la revendication 12 ou 13, dans lequel la seconde imprégnation des copeaux a pour résultat une teneur en silicates comprise entre 0,1 % et 10 %, par rapport au poids sec des copeaux et exprimée en dioxyde de silicium.
  18. Procédé selon la revendication 13, dans lequel la seconde imprégnation a pour résultat une teneur de copeaux en peroxyde comprise entre 0,5 et 10 %, calculée en peroxyde d'hydrogène et par rapport au poids sec des copeaux.
  19. Procédé selon la revendication 1 ou 6, dans lequel la troisième solution d'imprégnation a une teneur en peroxyde allant de 10 g par litre à 100 g par litre, calculée en peroxyde d'hydrogène, et a un pH compris entre 9 et 13.
  20. Procédé selon la revendication 19, dans lequel la troisième imprégnation a pour résultat une teneur des copeaux en peroxyde comprise entre 0,5 % et 10 %, calculée en peroxyde d'hydrogène et par rapport au poids sec des copeaux.
  21. Procédé selon la revendication 19, dans lequel la troisième solution d'imprégnation contient un stabilisant choisi parmi des stabilisants de peroxyde à base de magnésium et à base de silicates, et un agent chélateur pour la stabilisation contre la décomposition due à des ions métalliques.
  22. Procédé selon la revendication 1, dans lequel :
    (a) la première solution d'imprégnation a un pH compris entre 5 et 10 et contient :
    (i) des sels de magnésium solubles dans l'eau, à une concentration comprise entre 0,01 g par litre et 2,0 g par litre, exprimée en poids de magnésium, et
    (ii) un agent chélateur pour contaminants métalliques choisi parmi l'acide diéthylènetriaminepentaacétique, l'acide éthylène-diaminetétraacétique, l'acide hydroxyéthyléthylène-diaminetriacétique, l'acide nitrilotriacétique, le tripolyphosphate de sodium ou des dérivés d'acide phosphonique, à une concentration de l'agent chélateur dans la première solution d'imprégnation allant de 0,01 g par litre à 20 g par litre,
    (b) la seconde solution d'imprégnation a un pH qui est plus élevé que le pH de la première solution d'imprégnation et se situe entre 9 et 12, et contient :
    (i) du silicate de sodium a une concentration comprise entre 1,0 g par litre et 100 g par litre, de silicates exprimés en dioxyde de silicium, et
    (ii) un agent chélateur pour ions métalliques, choisi parmi l'acide diéthylène-triaminepentaacétique, l'acide éthylène-diaminetétraacétique, l'acide hydroxyéthyléthylène-diaminetriacétique, l'acide nitrilotriacétique, le tripolyphosphate de sodium ou des dérivés d'acide phosphorique, à une concentration allant de 0,01 g par litre à 20 g par litre,
    (c) les imprégnations des copeaux sont effectuées à une température comprise entre 15 et 100°C,
    (d) la première imprégnation a pour résultat une teneur en magnésium des copeaux comprise entre 0,001 % et 0,2 %, par rapport au poids sec des copeaux, et une teneur des copeaux en agent chélateur allant de 0,01 % à 2 % d'agent chélateur par rapport au poids sec des copeaux ;
    (e) la seconde imprégnation des copeaux a pour résultat une teneur des copeaux en agent chélateur allant de 0,01 % à 2,0 % par rapport au poids sec des copeaux, et une teneur en silicates comprise entre 0,1 et 10 % par rapport au poids sec des copeaux ;
    (f) la troisième solution d'imprégnation a un pH compris entre 11 et 13 et contient du peroxyde à une concentration de 10 g par litre à 100 g par litre, calculée en peroxyde d'hydrogène, pour donner une teneur des copeaux en peroxyde comprise entre 0,5 et 10 %, calculée en peroxyde d'hydrogène et par rapport au poids sec des copeaux.
  23. Procédé selon la revendication 3, dans lequel :
    (a) la première solution d'imprégnation a un pH situé entre 5 et 10, et contient :
    (i) des sels de magnésium solubles dans l'eau, à une concentration comprise entre 0,01 g par litre et 2,0 g par litre, exprimée en poids de magnésium, et
    (ii) un agent chélateur pour contaminants métalliques, choisi parmi l'acide diéthylènetriaminepentaacétique, l'acide éthylène-diaminetétraacétique, l'acide hydroxyéthylétylène-diaminetriacétique, l'acide nitrilotriacétique, le tripolyphosphate de sodium ou des dérivés d'acide phosphonique, à une concentration d'agent chélateur dans la première solution d'imprégnation allant de 0,01 g par litre à 20 g par litre;
    (b) la seconde solution d'imprégnation a un pH qui est plus élevé que le pH de la première solution d'imprégnation et se situe entre 9 et 13, et contient :
    (i) du silicate de sodium à une concentration comprise entre 1,0 g par litre et 100 g par litre, de silicates calculés et exprimés en dioxyde de silicium ;
    (ii) un agent chélateur pour ions métalliques, choisi parmi l'acide diéthylène-triaminepentaacétique, l'acide éthylène diaminetétraacétique, l'acide hydroxyéthyléthylène-diaminetriacétique, l'acide nitrilotriacétique, le tripolyphosphate de sodium ou des dérivés d'acide phosphoniques, à une concentration d'agent chélateur allant de 0,01 g par filtre à 20 g par filtre ;
    (iii)du peroxyde à une concentration allant de 10 g par litre à 100 g par litre, exprimée en peroxyde d'hydrogène, pour donner une teneur en peroxyde des copeaux comprise entre 0,5 et 10 %, calculée en peroxyde d'hydroxyde et par rapport au poids sec des copeaux, et
    (iv) un sel de magnésium soluble dans l'eau, à une concentration comprise entre 0,01 par litre et 2,0 g par litre, exprimée en poids de magnésium.
  24. Procédé selon la revendication 22 ou 23, dans lequel le matériau lignocellulosique est choisi parmi le bois tendre, le bois dur, le pin, l'épicéa, le tremble, l'eucalyptus, le gmelina, le hêtre, le chêne, le frêne, le sapin, le sapin du Canada, la bagasse et la paille.
  25. Procédé selon la revendication 22 ou 23, dans lequel on concentre la pâte après raffinage, pour éliminer la solution d'imprégnation résiduelle, et on recycle ladite solution d'imprégnation résiduelle, en tant que source de peroxyde à utiliser dans ladite troisième solution d'imprégnation.
  26. Procédé selon la revendication 1, dans lequel la seconde solution d'imprégnation contient un sel de magnésium soluble dans l'eau et a un pH compris entre 5 et 10, et la première solution d'imprégnation contient du silicate de sodium et a un pH qui est plus élevé que le pH de la seconde solution d'imprégnation et se situe entre 9 et 10.
  27. Procédé selon la revendication 2, dans lequel la seconde solution d'imprégnation a une teneur en dits sels de magnésium comprise entre 0,01 g par litre et 2,0 g par litre, exprimée en poids de magnésium.
  28. Procédé selon la revendication 6, dans lequel les imprégnations des copeaux sont effectuées à une température comprise entre 15 et 100°C.
  29. Procédé selon la revendication 6, dans lequel la seconde imprégnation des copeaux a pour résultat une teneur des copeaux en magnésium comprise entre 0,001 % et 0,2 %, par rapport au poids sec des copeaux.
  30. Procédé selon la revendication 6, dans lequel la seconde solution d'imprégnation contient un agent chélateur à une concentration allant de 0,01 g par litre à 20 g par litre.
  31. Procédé selon la revendication 9, dans lequel la seconde imprégnation des copeaux a pour résultat une teneur en agent chélateur allant de 0,001 à 2,0 %, par rapport au poids sec des copeaux.
  32. Procédé selon la revendication 12, dans lequel ladite solution d'imprégnation contient un agent chélateur pour des ions métalliques, à une concentration de 0,01 g par litre à 20 g par litre.
  33. Procédé selon la revendication 14, dans lequel ledit agent chélateur est choisi parmi l'acide diéthylène-triaminepentaacétique, l'acide éthylène-diaminetétraacétique, l'acide hydroxyéthyléthylènediaminetriacétique, l'acide nitrilotriacétique, le tripolyphosphate de sodium ou des dérivés d'acide phosphonique.
  34. Procédé selon la revendication 14, dans lequel la première imprégnation des copeaux a pour résultat une teneur des copeaux en agent chélateur allant de 0,001 % à 2,0 %, par rapport au poids sec des copeaux.
  35. Procédé selon la revendication 5, dans lequel on concentre la pâte après raffinage pour éliminer la solution d'imprégnation résiduelle, et on recycle ladite solution d'imprégnation résiduelle, en tant que source de peroxyde à utiliser dans ladite troisième solution d'imprégnation.
  36. Nouvelle pâte de pin non sulfonée, ayant un rendement d'au moins 85 %, une blancheur supérieure à 70 % et une longueur à la rupture, dans la fabrication du papier, d'au moins 3,0 km à un indice d'égouttage de 600 ml.
  37. Nouvelle pâte de tremble non sulfonée, ayant un rendement d'au moins 80 %, une blancheur supérieure à 80 % et une longueur à la rupture, dans la fabrication du papier, d'au moins 4,0 km à un indice d'égouttage de 500 ml.
  38. Nouvelle pâte d'eucalyptus non sulfonée, ayant un rendement d'au moins 80 %, une blancheur supérieure à 80 % et une longueur à la rupture, dans la fabrication du papier, d'au moins 3,0 km à un indice d'égouttage de 500 ml.
  39. Nouvelle pâte de gmelina non sulfonée, ayant un rendement d'au moins 80 %, une blancheur supérieure à 75 % et une longueur à la rupture, dans la fabrication du papier, d'au moins 2,0 km à un indice d'égouttage de 500 ml.
EP19860905113 1985-09-20 1986-08-13 Procede de pre-traitement d'une pulpe avec des stabilisateurs et du peroxyde avant le raffinage mecanique Expired - Lifetime EP0239583B2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US77845785A 1985-09-20 1985-09-20
US778457 1985-09-20

Publications (4)

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EP0239583A1 EP0239583A1 (fr) 1987-10-07
EP0239583A4 EP0239583A4 (fr) 1988-03-22
EP0239583B1 EP0239583B1 (fr) 1991-01-02
EP0239583B2 true EP0239583B2 (fr) 1994-01-12

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EP (1) EP0239583B2 (fr)
AR (1) AR243622A1 (fr)
AU (3) AU605745B2 (fr)
BR (1) BR8606875A (fr)
CA (1) CA1274657A (fr)
DE (1) DE3676490D1 (fr)
ES (1) ES2002755A6 (fr)
MX (1) MX174399B (fr)
PT (1) PT83406B (fr)
WO (1) WO1987001746A1 (fr)

Families Citing this family (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE458690B (sv) * 1986-11-06 1989-04-24 Sunds Defibrator Saett att framstaella mekanisk massa fraan lignocellulosahaltigt material i styckeform med en laengd i fiberriktningen av minst 200 mm
CA2057231A1 (fr) * 1991-01-07 1992-07-08 Ulrike Tschirner Methode pour le pretraitement de matieres lignocellulosiques avant le depulpage alkalin a haut rendement au peroxyde
FR2672315B1 (fr) * 1991-01-31 1996-06-07 Hoechst France Nouveau procede de raffinage de la pate a papier.
CA2631545C (fr) * 2005-12-02 2014-08-19 Akzo Nobel N.V. Procede de production de pate a haut rendement
US8268122B2 (en) 2005-12-02 2012-09-18 Akzo Nobel N.V. Process of producing high-yield pulp
US9273270B2 (en) 2014-02-20 2016-03-01 Church & Dwight Co., Inc. Unit dose cleaning products for delivering a peroxide-containing bleaching agent

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE496197C (de) * 1928-05-15 1930-04-17 Carl G Schwalbe Dr Verfahren zur Herstellung von Zellstoff aus verholzten Fasern
CA895757A (en) * 1970-04-03 1972-03-21 E. Worster Hans Single-stage soda-oxygen pulping
US4187141A (en) * 1975-02-24 1980-02-05 Alf Societe Anonyme Method of producing bleached mechanical pulp
SE436368B (sv) * 1979-01-12 1984-12-03 Sunds Defibrator Sett att framstella blekta, mekaniska, kemimekaniska och halvkemiska massor av lignocellulosahaltiga fibermaterial
JPS63402A (ja) * 1986-06-18 1988-01-05 Toyota Motor Corp 焼結鍛造用原料粉末およびその粉末を使用した焼結鍛造法

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Publication number Publication date
AU6658290A (en) 1991-01-31
EP0239583A1 (fr) 1987-10-07
PT83406A (en) 1986-10-01
AU6225386A (en) 1987-04-07
EP0239583A4 (fr) 1988-03-22
EP0239583B1 (fr) 1991-01-02
ES2002755A6 (es) 1988-10-01
AR243622A1 (es) 1993-08-31
PT83406B (pt) 1989-05-12
AU663781B2 (en) 1995-10-19
BR8606875A (pt) 1987-11-03
WO1987001746A1 (fr) 1987-03-26
AU605745B2 (en) 1991-01-24
CA1274657A (fr) 1990-10-02
MX174399B (es) 1994-05-13
DE3676490D1 (de) 1991-02-07
AU3984493A (en) 1993-08-19

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