WO2007128024A1 - Procédé de fabrication d'une pâte de cellulose - Google Patents

Procédé de fabrication d'une pâte de cellulose Download PDF

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Publication number
WO2007128024A1
WO2007128024A1 PCT/AT2007/000222 AT2007000222W WO2007128024A1 WO 2007128024 A1 WO2007128024 A1 WO 2007128024A1 AT 2007000222 W AT2007000222 W AT 2007000222W WO 2007128024 A1 WO2007128024 A1 WO 2007128024A1
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Prior art keywords
cooking
pulp
liquor
stage
cbc
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PCT/AT2007/000222
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German (de)
English (en)
Inventor
Herbert Sixta
Andrea Promberger
Andrea Borgards
Roland MÖSLINGER
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Lenzing Aktiengesellschaft
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Publication of WO2007128024A1 publication Critical patent/WO2007128024A1/fr

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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
    • D21C3/00—Pulping cellulose-containing materials
    • D21C3/02—Pulping cellulose-containing materials with inorganic bases or alkaline reacting compounds, e.g. sulfate processes
    • 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
    • D21C11/00—Regeneration of pulp liquors or effluent waste waters
    • D21C11/0007—Recovery of by-products, i.e. compounds other than those necessary for pulping, for multiple uses or not otherwise provided for
    • 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
    • D21C3/22—Other features of pulping processes
    • D21C3/26—Multistage processes
    • 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
    • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
    • D21C9/10—Bleaching ; Apparatus therefor

Definitions

  • the present invention relates to a process for the production of a pulp from a cellulosic starting material by means of the kraft process.
  • One aspect of the present invention relates in particular to a combined production of paper and chemical pulps.
  • the yield and thus capacity loss in the production of chemical pulp is more than 25% (50.8% vs. 37.7%, respectively, completely bleached pulps) compared to paper pulp production.
  • Chemical pulps are mainly processed into cellulosic fibers by the viscose and lyocell process. During the past few years, the cost position of regenerated fibers has further deteriorated over competing synthetic fibers. Reducing pulp costs, which are the most significant cost factor, would significantly improve the cost position of regenerated fibers.
  • Luo et al. were able to show that conventional kraft pulp after adaptation of the average degree of polymerization (DP) by means of acid-hydrolytic or oxidative degradation is suitable for producing cellulosic fibers by the lyocell method [WO 99/47733].
  • the kraft pulps produced according to this prior art have a hemicellulose content of at least 7% by weight.
  • Lyocell fibers which are produced from these kraft pulps have, according to WO 99/47733, a hemicellulose content of at least 5% by weight to 27% by weight.
  • the measurement method used to determine hemicellulose content is not disclosed.
  • Hemicellulose components on the process behavior enrichment of non-fiber-forming hemicellulose components in the spinning bath, high depolymerization chemicals for setting the desired DP
  • the textile-mechanical properties more than 5 cN / tex lower strength under conditioned conditions compared to lyocell fibers from prehydrolysis kraft pulps
  • the high-molecular hemicelluloses are further concentrated by means of pressure-driven membrane separation processes before being replated in the post-bleach in the course of an E-stage on the surface of the pulp fibers, on the one hand to increase the yield and, on the other hand, to increase the static strength.
  • Another requirement of a pulp cooking process is the selectivity of the process, i. the intrinsic viscosity of the pulp produced as a function of its kappa number.
  • the present invention has as its object to provide a process for the production of pulp, which solves the above-described problems of pulp production according to the Kraft process in an improved manner.
  • a process for producing a pulp from a cellulosic starting material by means of the Kraft process which comprises the step of cooking the starting material with a cooking liquor and is characterized in that the cooking step is carried out in two stages, wherein in the first Stage delignification is carried out by means of a first cooking liquor to a kappa number of 35 to 70 in the case of coniferous wood as starting material and to a kappa number of 30 to 60 in the case of Laubhölzem as starting material, and in the second stage the cooking is continued up to the desired degree of purity of the pulp by means of a second cooking liquor.
  • the present invention is thus based on the concept of a two-stage power cooking.
  • the task of the first Kochtos is to perform the bulk of the bulk delignification.
  • coniferous woods are delignified to a kappa number of 35 to 70 or deciduous trees to a kappa number of 30 to 60.
  • the proportion of the H-factor of the first cooking stage based on the H-factor of both cooking stages together, preferably 40% to 80% in the case of coniferous wood as starting material or 20% to 60% in the case of hardwoods as starting material.
  • the H-factor defines the relative speed of the lignin dissolution and depends on the cooking time and the temperature.
  • the H-factor expresses the cooking time and the cooking temperature as a single variable.
  • a relative reaction rate (with reference to a temperature of 100 ° C where the reaction rate is by definition 1) calculated by means of an Arrhenius approach using a certain activation energy is integrated over the time of the cooking.
  • the first cooking liquor is replaced by the second cooking liquor in the transition from the first to the second cooking stage.
  • the supply of the first cooking liquor can be stopped and at the same time the supply of the second cooking liquor from a second cooking liquor tank can be started.
  • the choice of suitable flow rates allows a largely complete entry of cooking liquors during the two cooking phases.
  • the first cooking liquor preferably has an EA (effective alkali) concentration of 10 g / L to 30 g / L, preferably 15 g / L to 25 g / L, particularly preferably 20 g / L, and a sulfidity of 50% to 120%. , preferably 100%, on.
  • EA effective alkali
  • the composition of the second cooking liquor differs from that of the first cooking liquor.
  • the composition of the second cooking liquor can be adapted to the respective requirements of the pulp quality, in particular by admixing suitable liquor streams. In principle one can differentiate between three different types of lye:
  • the second cooking liquor may be enriched with an alkali selected from the group consisting of the filtrate of a subsequent washing stage, a white liquor from the causticizing, the caustic liquor from a cold alkali extraction stage and the retentate of a membrane separation process carried out on a caustic liquor from a cold alkali extraction stage.
  • an alkali selected from the group consisting of the filtrate of a subsequent washing stage, a white liquor from the causticizing, the caustic liquor from a cold alkali extraction stage and the retentate of a membrane separation process carried out on a caustic liquor from a cold alkali extraction stage.
  • both cooking stages are preferably carried out in the form of a continuous batch cooking (CBC).
  • CBC continuous batch cooking
  • the CBC technology is known, for example, from EP 0 891 438 B1 and from Wizard, W., et al. "CBC - Continuous batch cooking The revolution in force cooking” in Pulping Process and Product Quality Conference, 2000, Boston, MA, USA. This technology offers greater flexibility in designing the second cooking stage.
  • modified continuous cooking processes the addition of either hemicellulose-rich or hemicellulose-poor cooking liquor in the countercurrent cooking zone (MCC and EMCC / ITC cooking process) or in the extended cooking zone (EMCC / ITC cooking process) is appropriate.
  • the starting material is subjected to a steam treatment before the first cooking step and the pulp obtained by the cooking is subjected in the course of further treatment of a cold-alkali extraction (CCE).
  • CCE cold-alkali extraction
  • the steaming is preferably carried out at a temperature of 120 ° C. or more and a P-factor of 50 or less. These are significantly more intensive conditions than with a "low temperature steaming", as described for example in WO 98/15687.
  • an increase in the porosity of the digestion material (wood chips) as well as partial cleavage of the lignin-carbohydrate bonds is achieved by the steam treatment.
  • P-factors greater than 50 are achieved.
  • the concept of the "P-factor” is described, for example, in “Handbook of PowerPoint", Vol. 1, Wiley-VCH 2006, pages 343-345.
  • the intensity of fiction, according to preferred steam treatment is preferably only about one-tenth of a conventional prehydrolysis.
  • the starting material is particularly preferably treated at a temperature of 150 to 180 ° C with medium pressure steam.
  • the starting material can be subjected to impregnation before the first boiling stage. If a steam treatment is also carried out, the impregnation takes place after the steam treatment.
  • the impregnation and hot displacement steps i.e., the displacement of the impregnation liquor by cooking liquor
  • the impregnation and hot displacement steps are in accordance with the method familiar in CBC technology.
  • both cooking stages and optionally the steam treatment and / or the impregnation of the starting material can be carried out in the same digester.
  • the kraft pulps produced according to the invention can be subjected to TCF or ECF bleaching in a manner known per se in order to achieve the required purity and whiteness. It turns out that the two-stage boiled pulps according to the invention have a high bleachability. Paper pulps produced according to the invention can therefore be bleached under very mild conditions, whereby the strength properties are hardly impaired.
  • At least a portion of the resulting in the cold-alkali extraction stage press liquor of the second cooking liquor of the cooking method according to the invention can be mixed.
  • This is suitable, as shown above under (c), in particular in a process for the production of high-yield paper pulps with increased hemicellulose content.
  • part of the press liquor produced in the cold-alkali extraction stage can be purified by means of a membrane separation process, preferably a nano- or an ultrafiltration, and at least a portion of the retentate of the membrane separation process can be admixed with the second cooking liquor.
  • the purification of the caustic liquor of a C CE process by means of a membrane separation process is described in WO 2005/118923.
  • the accumulating retentate contains the entire amount of beta-cellulose in the press liquor and more than half of the Gamma-cellulose.
  • the beta cellosolve solution consists of almost pure xylan.
  • the membrane separation process can be carried out in two stages, wherein between the two separation stages, a dilution of the retentate of the first stage with water runs Runaway.
  • a nanofusion of the diluted retentate or a dialysis of the retentate of the first stage can be performed. In both cases, this step increases NaOH recovery while concentrating the hemicellulose phase.
  • the hemicelluloses contained therein, in particular xylans can be obtained from at least part of the retentate of the membrane separation process.
  • US 2005/0203291 describes a process for obtaining xylans from a xylan-rich phase.
  • precipitated hemicelluloses in particular the xylans, are obtained from the retentate of the membrane separation process by means of a reversed precipitation in a preferred embodiment of the method according to the invention.
  • xylans thus obtained can be at least partially processed to xylo-oligosaccharides.
  • Xylooligosaccharides have various uses, for example as a prebiotic active food additive.
  • xylo-oligosaccharides preference may be given to a process selected from the group consisting of hydrothermolysis and enzymatic hydrolysis.
  • a further preferred embodiment of the method according to the invention is characterized in that on the obtained by the cooking pulp in the course of Further treatment in addition to a possibly performed bleaching step, a treatment for adjusting the degree of polymerization (DP) is performed.
  • DP degree of polymerization
  • the treatment is preferably selected from the group consisting of oxidative bleaching processes, acid hydrolysis processes and electron beam irradiation processes.
  • the DP degradation of pulps to a desired DP level can be accomplished by both chemical oxidative and electron beam irradiation. Hypochlorite or ozone treatments are best suited as oxidizers for DP degradation.
  • a disadvantage of chemical-oxidative processes is that due to limited accessibility (the oxidizing agent) in the crystalline regions of the chain degradation is very heterogeneous, whereby the molecular weight distribution remains significantly wider than would correspond to a statistical degradation.
  • the present invention circumvents this problem by removing the pulps at arbitrary positions of the fiber line, i. during the manufacturing process of the pulp, starting from the unbleached pulp until before the last bleaching stage, subjected to electron beam irradiation ("EBeam" treatment).
  • EBeam electron beam irradiation
  • the electron irradiation of the pulp may preferably be carried out such that the pulp is present in a pulp density of at least 35%, preferably 40-50% and in a layer thickness of 2 to 6 mm, preferably 3 to 4 mm, and an acceleration voltage of less than 2 , 5 MeV is used.
  • Layer thicknesses between 2 and 6 mm can also be low
  • Acceleration voltages can be largely homogeneously irradiated.
  • the amount of water present in the pulp web must be taken into account when choosing the irradiation dose.
  • the dose required for a particular DP degradation is roughly doubled at a consistency of 50%.
  • Another favorable embodiment of the method according to the invention consists in that, after the treatment for adjusting the degree of polymerization, an alkaline-oxidative treatment, preferably an alkaline peroxide treatment, is carried out.
  • TCF bleaching sequence
  • W-EBeam-OP-A-Z-P W-EBeam-OP-A-Z-P; W-EBeam-OP-A-P, W-EBeam-OP-P, W-OP-A-Z-EBeam-P, W-OP
  • W-EBeam-OP-D-E-P W-EBeam-OP-D-E-P; W-EBeam-OP-D-E-D, W-EBeam-D-E-D, W-D-E-EBeam-P
  • W laundry
  • OP peroxide-enhanced oxygen delignification
  • E alkaline extraction
  • D chloride dioxide
  • Z ozone
  • P alkaline peroxide
  • the present invention also relates to the use of the inventive chemical pulps for the production of viscose and lyocell fibers.
  • the starting material is subjected to a steam treatment before cooking and the pulp obtained by the cooking is subjected in the course of further treatment of a cold-alkali extraction (CCE), are outstanding for the production of viscose and lyocell fibers.
  • CCE cold-alkali extraction
  • Lyocell fibers which are obtainable by spinning a chemical pulp produced according to the CBC * -CCE variant are characterized in particular by the following features:
  • Their content H of hemicellulose is preferably more than 3.5% by weight and is thus slightly higher than the hemicellulose content of lyocell fibers which are produced from high-quality and costly (i.e. in particular with comparatively low yield) prehydrolysis kraft pulps, e.g. in WO 94/12719.
  • the content H may be less than 5% by weight.
  • the mercerizing yield of the lyocell fiber according to the invention is 90% or more.
  • the lyocell fiber according to the invention has a significantly higher Mercerisierbe Onemaschinen than lyocell fibers, which consist of a non-inventive Kraft pulp with high hemicellulose content, as described, for example, in WO 99/47733.
  • the strength of the lyocell fiber according to the invention is 37 cN / tex or more in the conditioned state and is thus in the same size range, which was previously achievable only with the use of high-quality and expensive to produce Vo ⁇ ydrolyse-kraft pulps.
  • the lyocell fiber produced according to the invention also differs in that the average molar mass of the xylans isolatable from the fiber is 20 kDa or more (see the method of measurement described below).
  • xylans from lyocell fibers derived from high-quality prehydrolysis kraft pulps (or sulfite pulps) have a weight average (Mw) of ⁇ 10 kDa.
  • the lyocell fibers according to the invention are thus clearly distinguishable from hitherto known fibers and have the advantage that they have excellent fiber properties despite the use of the relatively inexpensive pulp which can be produced by the process according to the invention.
  • the present invention also relates to a viscose fiber obtainable by spinning a chemical pulp made according to the CBC * -CCE variant.
  • the fiction, contemporary viscose fiber is characterized in particular by the fact that their content H hemicellulose is more than 2.0 wt.% And their Mercerisierbe Onemaschine is 90% or more.
  • the strengths of the viscose fiber according to the invention are at the level of the best viscose fibers produced from high-quality prehydrolysis kraft pulps (or else sulfite pulps).
  • the viscose fiber of the present invention may have a strength in a conditioned state of 23 cN / tex or more and a stretch in a conditioned state of .18% or more.
  • FIG. 1 shows a diagram of the basic concept of the method according to the invention and its possible applications.
  • Figure 2 shows a plot of intrinsic viscosity vs. Kappa number of one- and two-stage CBC grades of spruce.
  • FIG. 3 shows temperature and hydroxide ion profiles of one-stage and two-stage softwood CBC cookings.
  • FIG. 4 shows a plot of total yield vs. Kappa number of one- and two-stage Eucalyptus globulus CBC boils with and without hemicellulosic enrichment.
  • Figure 5 shows a plot of intrinsic viscosity vs. Kappa number of one- and two-stage Eucalyptus globiilus CBC cookings with and without hemicellulosic enrichment.
  • FIG. 6 shows the molecular weight distribution of Eucalyptus globuhis kraft pulps.
  • FIG. 7 shows the comparison of the molecular weight distribution of a CBC * pulp with a VISCBC pulp.
  • FIG. 8 shows the strengths of normal viscose fibers produced from different pulps in the conditioned state.
  • Figure 9 illustrates the effect of ozone usage and dose on the DP degradation of various pretreated CBC and LH sulfite pulps.
  • FIG. 10 shows the molecular weight distribution of a CBC pulp degraded by means of EBeam and ozone to a GVZ of 440 ml / g.
  • FIG. 11 shows the molecular weight distribution of a xylan isolated from a CCE filtrate by reverse precipitation in mineral acid
  • FIG. 12 shows the molecular weight distribution of the xylans isolated by means of DMSO from pulps and fibers produced therefrom (graphic evaluation of the GPC analysis).
  • Figure 13 contrasts the intensity of the preferred steam treatment (CBC *) according to the invention to a prehydrolysis process (VISCBC).
  • the P-factor of the inventively preferred steam treatment is less than 50; the P-factor of VISCBC prehydrolysis at 700.
  • the present invention is based on a two-stage force process that can be used flexibly to produce all of the chemical pulp qualities (from high yield paper to high purity chemical pulp).
  • the inventive method can be used to produce a paper pulp with high strength potential:
  • the two-stage kraft process of the present invention (as a batch or e.g., CBC process) is combined with a TCF or ECF bleaching sequence.
  • the erfindungs like ate Zweimatnfahrweise allows optimal adaptation of the cooking conditions to the particular requirements.
  • Variant B shows the concept of producing a high yield pulp (pulp with increased hemicellulose content):
  • the process is basically the same as in variant A.
  • the cooking liquor for the second stage of the cooking is enriched here with high molecular weight hemicellulose from hemicelVulosereicher lye.
  • this hemicellulose-rich liquor may originate from a CCE process which is carried out in a process C coupled to process B to produce a high-yield lyocell pulp.
  • the hemicellulose-rich liquor may be e.g. (a) the CCE filtrate or (b) the retentate of a nanofiltered CCE filtrate.
  • variant C in FIG. 1 leads to a high-yield lyocell pulp for the production of lyocell fibers having the highest textile-mechanical strength properties.
  • the basic scheme is according to variant A.
  • the cooked pulp is here, either directly after washing and sorting or after each bleaching cycle. or Depolymerisationsbra ("DEPOLY”), preferably after an O-stage, treated in a CCE refining step.
  • DEPOLY Depolymerisationskin
  • CCE filtrate can be used to reinforce white liquor, preferably in the second cooking stage. If paper pulp production is absent or too low, the lye can be recylylated after purification by means of nanofueration.
  • the permeate (b) is recycled to the CCE stage, hemicelluloses can be obtained from the retentate (c).
  • Variant D in FIG. 1 shows a process for producing high-yield dissolving pulps, which is in particular (a) viscose pulp for fibers having high textile-mechanical properties, (b) all other dissolving pulps which are derivatized to cellulose ester or ether.
  • the basic scheme is according to variant C.
  • the wood is subjected to a steam activation treatment (DA stage), in which the composite structure of the wood is greatly loosened, with the aim of selectively separating the low molecular weight hemicelluloses in the subsequent alkaline boiling.
  • DA stage steam activation treatment
  • Spruce wood is cooked in a 10.8 1 large test cooker by the CBC (continuous batch cooking) method to pulp with kappa numbers between 16 and 42.
  • the single-stage reference cooking has the following conditions:
  • Target temperature of 160 ° C reached cooking stage Cook liquor is pumped from top to bottom in a flow rate of twice the volume of the cooker per hour through the cooker: 160
  • Impregnation and heating of the two-stage CBC cooking according to the invention were carried out analogously to the one-stage variant.
  • test results are summarized in FIG. 2 on the basis of a selectivity plot (limiting viscosity number vs. kappa number).
  • the results show that the already high selectivity of single-stage CBC boiling can be further improved by the two two-step variants.
  • FIG. 3 shows temperature and hydroxide ion profiles of the one- and two-stage softwood CBC cookings described above.
  • Eucalyptus globulus is processed into pulp with capillary numbers between 13 and 28 in a 10.8 1 large test cooker according to the CBC process (continuous batch cooking).
  • One-stage reference cooking (one-stage) has the following conditions:
  • Target temperature of 155 0 C reaches boiling level: cooking liquor is poured from top to bottom in a flow rate of
  • Impregnation and heating of the two-stage CBC cooking were carried out analogously to the single-stage variant.
  • the second stage cooking liquor was prepared with the hemi-rich filtrate of a CCE treatment.
  • the yield could be significantly improved in the entire kappa number range both for the "simple" two-stage variant ("hemi-add”) and for the hemicellulose-enhanced two-stage variant compared to the one-stage mode of operation become.
  • Example 3 Production of high-yield chemical pulps for further processing into viscose and lyocell fibers
  • the wood was subjected to steam activation (DA) before the start of the CBC cooking by bringing the digester contents with the aid of medium-pressure steam to a temperature of about 165 0 C.
  • DA steam activation
  • CBC * The combination of the DA + CBC processes is referred to as "CBC *" for better identification, and CBC * pulp became after O-delignification cold-alkali extracted, with the aim to remove the alkaloids looking for hemicelluloses.
  • the DP setting was carried out as part of the subsequent bleaching by an ozone treatment (Z).
  • Z The subsequent P-bleaching served to stabilize the cellulose and to set the desired final whiteness.
  • VISCBC modified Visbatch process, see Wizcmi, W., et al., "CBC - Continuous batch cooking, The revolutionary in force cooking” in Pvlp in g process and product Quality Conference, 2000, Boston, MA, USA).
  • the P-factor expresses the intensity of the prehydrolysis.
  • the calculation is based on the same concept as the H-factor, whereby a different activation energy (123 kJ / mol) is used.
  • the yield (cellulose content) of the CBC * pulp was higher by 15.7 percentage points (6.1 percentage points) compared to the VISCBC reference pulp (see Tab.l).
  • the CBC * and VISCBC pulps were then finish bleached using an OZP-TCF sequence.
  • the CBC * pulps were cold alkali extracted after an O-delignification (CCE stage).
  • the CCE treatment was performed at two different NaOH concentration levels, 50 g / L and 100 g / L.
  • the alkali source was white liquor with a sulphidity of 26%. All other conditions, such as temperature (30 0 C), residence time (30 min) and mass density (10%) were kept constant in both experiments.
  • the subsequent bleaching was carried out with the aid of a ZP sequence in all pulps, the task of ozone bleaching being primarily to adjust the DP to the level for regenerated pulps (DPv 950 - 1200, corresponds to an intrinsic viscosity number CV of 420 - 500 ml / g) , The most important process and pulp data (as part of pulp bleaching) are listed in Table 2 below.
  • the yield advantage is mainly due to the higher cellulose content.
  • the higher xylan content (alkali-resistant) of the CBC * -CCE pulps also contributes to the higher yield, which decreases with increasing NaOH concentration in the CCE stage.
  • FIG. 6 The upper part of Figure 6 shows unbleached CBC pulps made after a two-stage CBC cooking process.
  • CBC-two-stage “CBC hemi-add” refer to the pulps produced according to Example 2 with and without hemicellulose accumulation.
  • ⁇ -xylan refers to isolated xylan isolated from the CCE step.
  • FIG. 6 The lower part of FIG. 6 represents the following pulps:
  • a comparison with the molecular weight distribution of conventional, highly refined, chemical pulps made according to a prehydrolysis force process shows (see Figure 7) that the CCE treatment with the higher NaOH concentration level has a narrower distribution (lower polydispersity) than with allows the comparison pulp.
  • VISCBC prehydrolysis force process
  • a VISCBC pulp is subjected to a "CBC * CCE100 Depoly" pulp, a CBC * pulp that has undergone a CCE process with 100 g / l NaOH, and a depolymerization treatment (TCF bleach) was compared. Further processing to regenerated fibers
  • Table 3 shows that the steam activation treatment prior to CBC cooking is the critical step in improving the resulting viscose quality.
  • the subsequent CCE treatment leads to a further improvement of the viscose quality, whereby, as expected, the effect increases with increasing NaOH concentration.
  • Table 3 shows that the quality of the viscose made from the CBC * -CCE100 pulp is nearly equivalent to that prepared from the reference VISCBC cell stock.
  • the viscoses were filtered and spun on a laboratory spinning machine with 20 holes ( ⁇ 50 ⁇ m) at a total of 4 different draw ratios.
  • the strengths of the produced normal viscose fibers in the conditioned state are summarized in FIG. These fibers are made of a) CBC paper pulp b) CBC * -CCE pulp and a c) VISCBC reference pulp compared.
  • the pulp "SolucelT is a VISCBC pulp.
  • the content of hemicellulose is the sum of the non-glucose-containing sugar constituents (calculated as anhydro-sugars) after a total hydrolysis (two-stage hydrolysis with sulfuric acid) of the pulp or fiber.
  • the measurement is carried out by means of anion exchange chromatography combined with pulsed amperometry as a detection method.
  • the measuring methodology is described in U. Maize, H. Sixta, ACS Symposium Series 2004, 864, 94, and H. Sixta et. Al. Proceedings of the 1st International ISWPC 2001, Vol. 3, pp. 655-658.
  • the fibers are extracted for 3 hours on a Soxhlet extractor with 96% EtOH and dried overnight at 50 ° C under vacuum.
  • the pulp “High Hemi” is a pulp corresponding to the teaching of WO 99/47733
  • the pulp “Solucell” is a VISCBC pulp.
  • the lyocell fibers according to the invention clearly exceed the properties of fibers produced from a pulp according to the teaching of WO 99/47733.
  • the ozone bleaching was carried out at 10% consistency and pH 2.0 by mixing in a high-shear mixer under fiuid obtainden conditions.
  • the EBeam treatment was carried out at 10 MeV accelerating voltage by IBA SA of Louvain-La-Neuve in a Rhodotron Accelerator after drying the pulp sheets.
  • the hemicellulose-poor CBC-CCE 100 pulp requires only about 3 kg O 3 / t for a 5.6 KSP (GVZ degradation from 750 ml / g to 420 ml / g), while a CBC pulp contains four times as much xylan (see Table 2) for the same degradation performance more than 12 kg O 3 / t needed.
  • the electron irradiation is different: The required dose for a particular DP degradation here is largely independent of the type of pulp and pulp composition.
  • Table 7 confirms the stabilizing effect of an alkaline peroxide treatment following the degradation processes on the basis of the copper number and carboxyl group contents.
  • the P-stage causes after both degradation processes an additional KSP of about 0.6 - 1.2, depending on the respective conditions.
  • Table 7 Copper number and carboxyl group content of CBC * -CCE100 pulps after Z, EBeam or subsequent alkaline peroxide bleaching
  • the use of hemicellulose-rich cooking liquor in the second cooking stage primarily causes an increase in pulp yield.
  • the average yield increase (at a hemoconcentration of about 10 g / l in the cooking liquor) is about 2% ⁇ points compared to the single-stage variant over a wide kappa number range (see FIG. 4).
  • NF pilot nanofiltration
  • a CCE filtrate was prefiltered using a candle filter (Profile Star ABl A4007J) to filter out residual fibers and undissolved particles.
  • the NF system was operated at a temperature of 40 ° C, a pressure of 25 bar and a specific flow rate of 5 l / m 2 .h.
  • the beta-cellulose (xylan) concentration in the feed was about 15 g / l, the NaOH concentration 90 g / l. In equilibrium, the flow rates and thus the liquor loads in the permeate to retentate behaved as 0.82: 0.18.
  • the total amount of beta-cellulose in the retentate was about 85 g / l.
  • the retentate was diluted with water in a ratio of 1: 1.5 and fed again to the NF.
  • the NF conditions of the second stage were comparable to those of the first stage, only the permeate dropped to about 70% of the feed amount.
  • the beta-cellulose in the retentate of the second NF stage was now present at a concentration of about 115 g / l and a NaOH concentration of about 32 g / l (hemilauge).
  • This substrate was used to isolate the beta-cellulose (xylan) by reverse precipitation with mineral acid.
  • a sulfuric acid diluted 1: 3 with water were mixed with 1 part of hemi-lye, in the end a pH of between 4 and 5 being established.
  • XOS was prepared from xylan in two ways, (A) hydrothermolytically, (B) enzymatically:
  • the solution was then neutralized to pH 6.5-7.0 with 0.3N NaOH.
  • the water-soluble products were centrifuged off at 4000 rpm for 60 min.
  • the isolated amount of XOS was 189.7 g of freeze-dried powder, corresponding to a yield of 59.6% based on the xylan used.
  • the hydrothermally produced XOS mixture shows a relatively uniform composition over the examined DP range (see Table 8 below).
  • the reaction was carried out in a 7L fermentor with 6 L charge, the xylan concentration was 20 g / L (120 g xylan).
  • the preparation was likewise carried out with the enzyme pentopane mono BG, but with an increased concentration of 1 g / L (50 mg / g xylan).
  • the fermentation was carried out at 40 ° C for 96 h.
  • the workup was as described above.
  • the XOS yield was 78% based on the amount of xylan used (93.66 g XOS).
  • the product consists mainly of xylobiose (Table 8).
  • Example 7 Molar mass distribution (MMV) of hemicelluloses (XylaneV isolated from pulps and fibers produced according to the invention
  • the hemicelluloses are purified by DMSO according to the method of D. Evtuguin et al. (Carboh. Res. 338 (2003) 597) extracted from the substrates (pulp, or fibers) and purified. Fibers are previously de-averted with EtOH (25 g Soxhlet with 1 L EtOH, 6 h). The isolated xylan (5 mg) is suspended in DMAc (1 mL) and dissolved by the addition of LiCl (8 mg) at room temperature molecularly dispersed.
  • the molecular weight distribution is determined by GPC under the following conditions: eluent: LiCl / DMAc; Temperature: room temperature; Separation column: Mixed A from Polymer Labs; Detection: MALLS (Wyatt) / RI; Refractive index increment: 0.136 mL / g.
  • the pulp "Solucell-1772" is a VISCBC pulp.
  • Xylans from CBC * -CCE pulps are significantly higher molecular weight and more polydisperse than those from conventional prehydrolysis kraft pulps (PHK).
  • Lyocell fiber xylans made by using a CBC ⁇ -CCE pulp have a weight average (Mw) of ⁇ 20 lcDa.
  • xylans from lyocell fibers derived from commercial PHK pulps (or sulfite pulps) today have a weight average (Mw) of ⁇ 10 kDa.

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Abstract

L'invention concerne un procédé de fabrication d'une pâte de cellulose à partir d'une matière première cellulosique par le procédé kraft, lequel procédé comprend l'étape de cuisson de la matière première à l'aide d'une liqueur de cuisson. Le procédé selon l'invention se caractérise en ce que cette étape de cuisson est effectuée en deux phases. Au cours de la première phase, une délignification est effectuée à l'aide d'une première liqueur de cuisson à un indice kappa de 35 à 70, lorsque des bois résineux sont utilisés comme matière première, et à un indice kappa de 30 à 60, lorsque des bois feuillus sont utilisés comme matière première. Au cours de la seconde phase, la cuisson est poursuivie à l'aide d'une seconde liqueur de cuisson, jusqu'à ce que le degré de pureté souhaité de la pâte de cellulose soit obtenu.
PCT/AT2007/000222 2006-05-10 2007-05-09 Procédé de fabrication d'une pâte de cellulose WO2007128024A1 (fr)

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014086883A1 (fr) * 2012-12-06 2014-06-12 Lenzing Aktiengesellschaft Procédé de production d'un article façonné cellulosique
CN104345125A (zh) * 2014-09-23 2015-02-11 朱琳 一种快速评价柳木硫酸盐法制浆工艺的方法
CN112262240A (zh) * 2018-06-15 2021-01-22 维美德公司 用于在硫酸盐法制浆中优化滤液循环的方法和组件

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US4849052A (en) * 1983-08-24 1989-07-18 Beloit Corporation Batch digester multi-stage pulping process
US5522958A (en) * 1994-07-18 1996-06-04 Pulp And Paper Research Institute Of Canada Two-stage kraft cooking
JPH09268487A (ja) * 1996-03-27 1997-10-14 Mitsubishi Paper Mills Ltd クラフトパルプの製造方法
US5736006A (en) * 1996-10-10 1998-04-07 Ahlstrom Machinery Inc. Method and apparatus for pulping with controlled heating to improve delignification and pulp strength
WO2000011261A1 (fr) * 1998-08-24 2000-03-02 Kvaerner Pulping Aktiebolag Procede permettant de precipiter de l'hemicellulose sur des fibres afin d'ameliorer le rendement et l'aptitude au raffinage
JP2000136491A (ja) * 1998-10-30 2000-05-16 Mitsubishi Paper Mills Ltd クラフトパルプの製造方法
JP2000136490A (ja) * 1998-10-30 2000-05-16 Mitsubishi Paper Mills Ltd クラフトパルプの製造方法
EP0891438B1 (fr) * 1996-04-04 2001-07-04 Lenzing Technik GmbH & CO. KG Procede de guidage en continu de liquides lors du lessivage de la pate dans un lessiveur
US20010032711A1 (en) * 1998-10-26 2001-10-25 C. Bertil Stromberg Pulp cooking with particular alkali profiles
EP1435403A1 (fr) * 2003-01-02 2004-07-07 Weyerhaeuser Company Verwendung von Holz mit niedrigem spezifischem Gewicht zur Herstellung von Lyozellprodukte
WO2005118950A1 (fr) * 2004-06-02 2005-12-15 Lenzing Aktiengesellschaft Procede de production d'une pate chimique

Patent Citations (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4849052A (en) * 1983-08-24 1989-07-18 Beloit Corporation Batch digester multi-stage pulping process
US5522958A (en) * 1994-07-18 1996-06-04 Pulp And Paper Research Institute Of Canada Two-stage kraft cooking
JPH09268487A (ja) * 1996-03-27 1997-10-14 Mitsubishi Paper Mills Ltd クラフトパルプの製造方法
EP0891438B1 (fr) * 1996-04-04 2001-07-04 Lenzing Technik GmbH & CO. KG Procede de guidage en continu de liquides lors du lessivage de la pate dans un lessiveur
US5736006A (en) * 1996-10-10 1998-04-07 Ahlstrom Machinery Inc. Method and apparatus for pulping with controlled heating to improve delignification and pulp strength
WO2000011261A1 (fr) * 1998-08-24 2000-03-02 Kvaerner Pulping Aktiebolag Procede permettant de precipiter de l'hemicellulose sur des fibres afin d'ameliorer le rendement et l'aptitude au raffinage
US20010032711A1 (en) * 1998-10-26 2001-10-25 C. Bertil Stromberg Pulp cooking with particular alkali profiles
JP2000136491A (ja) * 1998-10-30 2000-05-16 Mitsubishi Paper Mills Ltd クラフトパルプの製造方法
JP2000136490A (ja) * 1998-10-30 2000-05-16 Mitsubishi Paper Mills Ltd クラフトパルプの製造方法
EP1435403A1 (fr) * 2003-01-02 2004-07-07 Weyerhaeuser Company Verwendung von Holz mit niedrigem spezifischem Gewicht zur Herstellung von Lyozellprodukte
WO2005118950A1 (fr) * 2004-06-02 2005-12-15 Lenzing Aktiengesellschaft Procede de production d'une pate chimique

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2014086883A1 (fr) * 2012-12-06 2014-06-12 Lenzing Aktiengesellschaft Procédé de production d'un article façonné cellulosique
CN104345125A (zh) * 2014-09-23 2015-02-11 朱琳 一种快速评价柳木硫酸盐法制浆工艺的方法
CN104345125B (zh) * 2014-09-23 2016-02-17 周栋 一种快速评价柳木硫酸盐法制浆工艺的方法
CN112262240A (zh) * 2018-06-15 2021-01-22 维美德公司 用于在硫酸盐法制浆中优化滤液循环的方法和组件

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