Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
  • D21D1/00—Methods of beating or refining; Beaters of the Hollander type
  • D21D1/20—Methods of refining
• • 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
  • D21C9/001—Modification of pulp properties
• • 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
• • 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
  • D21C9/1026—Other features in bleaching processes
  • D21C9/1042—Use of chelating agents
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • 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
  • D21C9/1078—Bleaching ; Apparatus therefor with Mn-containing compounds
• • 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
  • D21C9/16—Bleaching ; Apparatus therefor with per compounds
  • D21C9/163—Bleaching ; Apparatus therefor with per compounds with peroxides
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21D—TREATMENT OF THE MATERIALS BEFORE PASSING TO THE PAPER-MAKING MACHINE
  • D21D1/00—Methods of beating or refining; Beaters of the Hollander type
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
  • D21F1/00—Wet end of machines for making continuous webs of paper
  • D21F1/0009—Regulating the freeness of the pulp

Definitions

• the present invention relates to a new refining process for paper pulp.
• Pulp for making paper, tissues, board or related products may be obtained from cellulose from wood and other sources (e.g., hemp, straw, cotton).
• wood pulp which can be either softwood or hardwood raw material.
• Softwood fibres come from needle-bearing conifer trees such as pine, spruce, alpine fir, Douglas fir.
• Hardwood fibres are derived from deciduous trees of various types, such as birch, eucalyptus, and acacia.
• Mechanical pulp contains most of the original lignin, whilst in chemical pulp most of the lignin has been removed.
• SW softwood
• HW hardwood
• Hardwood and softwood must be subjected to specific mechanical treatments (refining) for converting the wood into a fibrous slurry employed in the formation of a paper web.
• the fibres of cellulose pulp suspensions are mechanically treated to change the fibres properties.
• the cellulose pulp suspension is processed into a product having increased tensile/tear strength properties, increased freeness (Shopper-Riegler) values, increased fines, and improved paper/tissue making properties over that of the initial cellulose pulp suspension.
• Increased freeness values lead to decreased dewatering capabilities for paper/tissue making, which increases the energy required to dry the paper and it will slow down the speed of paper making.
• too low freeness yields paper/tissues that are not strong enough.
• Refining is of importance to the properties of both chemical and mechanical pulp. Apart from the dewatering, it should also be noted that the energy consumption during the refining process is high.
• WO 2004/022842 discloses a reduced energy process for refining mechanical pulp after treatment with a pectinase enzyme to produce pulp with certain freeness properties.
• EP 0458397 discloses the use manganese 1,4,7-Trimethyl-1,4,7-triazacyclononane (Me 3 -TACN) complexes as bleaching and oxidation catalysts and use for textile and pulp bleaching processes.
• Me 3 -TACN manganese 1,4,7-Trimethyl-1,4,7-triazacyclononane
• WO 2007/125517 discloses the use of 1,2,-bis-(4,7,-dimethyl-1,4,7,-triazacyclonon-1-yl)-ethane and Me 3 -TACN (Me 4 -DTNE) with buffer and sequestrants for bleaching of cellulosic substrates.
• WO 2008/086937 discloses the use of 1,2,-bis-(4,7,-dimethyl-1,4,7,-triazacyclonon-1-yl)-ethane and Me 3 -TACN (Me 4 -DTNE)for bleaching of cellulosic substrates whilst keeping the pH constant.
• the present invention may be applied to chemical and mechanical pulp, including recycling pulp, for production of paper, tissue or board.
• the present invention provides a method for the treatment of a cellulose pulp suspension comprising (i) the step of subjecting cellulose pulp fibres to an aqueous solution of a manganese transition metal catalyst and hydrogen peroxide at pH from 6 to 13 and (ii) subjecting the pulp to a refining process until a Shopper Riegler (SR) value of from 10 to 90° is reached and the resultant pulp is processed into paper, tissue or board, wherein the manganese transition metal catalyst is present at a concentration from 0.0001 to 1 kg/tonne oven-dry pulp and the hydrogen peroxide is present at a concentration from 0.1 to 100 kg/tonne oven-dry pulp, the manganese transition metal catalyst is preformed and a mononuclear Mn(II), Mn(III), Mn(IV) or dinuclear Mn(II)Mn(II), Mn(II)Mn(III), Mn(III)Mn(III), Mn(III)Mn(IV) or Mn(IV)
• the Freeness value (SR) is a standard measurement as measured by Shopper Riegler method for Drainability NORM EN ISO 5267-1; the Freeness value (SR) as used herein has been measured by this method.
• the concentration of the catalyst and hydrogen peroxide will have an effect upon the time of refining treatment of the pulp that is required as will the ratio of the mass of pulp to amount of actives used.
• the variables of concentration of actives, temperature, pH and time are variables that may be changed.
• the treatment time of the pulp with the catalyst and hydrogen peroxide is from 1 min to 4 h, more preferred 5 min to 3 h, and most preferred 10 min to 2 h. Further, it is preferred that the temperature of the process using the catalyst and hydrogen peroxide is from 30 to 95 °C and more preferably between 40 to 90 °C.
• the pH of the process using the catalyst and hydrogen peroxide is preferably between pH 8 and 12.
• the amount of transition metal catalyst/hydrogen peroxide required per tonne of pulp (oven dry) is essentially that of a molar ratios but within the industry it is normal to express amounts in weight.
• the range of transition metal catalyst required per tonne of pulp (oven dry) is in the range from 0.0001 to 1 kg per tonne of pulp (oven dry) which equates approximately to 0.1 to 1500 mmol/tonne pulp (oven dry).
• the hydrogen peroxide (100%) per tonne of pulp (oven dry) is in the range from 0.1 to 100 kg, more preferably 0.5 to 50 kg, most preferably 1 to 30 kg.
• the molar ratio of transition metal catalyst: hydrogen peroxide is preferably in the range from 1:100 to 1:10000.
• Pulp to produce paper or board grades is fed to a paper machine where it is formed as a paper web and the water is removed from it by pressing and drying. Pressing the sheet removes the water by force. Once the water is forced from the sheet, felt is used to collect the water. When making paper by hand, a blotter sheet is used. Pulp for the manufacturing of tissue or kitchen towel grades is dewatered and dried without pressing, to maintain the appropriate absorbancy and smoothness properties.
• Drying involves using air and or heat to remove water from the paper sheet. In the earliest days of papermaking this was done by hanging the paper sheets like laundry. In more modern times, various forms of heated drying mechanisms are used. On the paper machine, the most common is the steam-heated can dryer. These dryers can heat to temperatures above 200°F (93°C) and are used in long sequences of more than 40 cans. The heat produced by these can easily dry the paper to less than 6% moisture.
• treating a cellulose pulp suspension with a manganese transition metal catalyst and hydrogen peroxide changes the extent to which the pulp reacts to a mechanical refining process, as measured by its freeness value (Shopper-Riegler - SR), to produce a web made from the cellulose pulp suspension.
• Treatment by the manganese catalyst can be either done before the mechanical refining, during, or after the mechanical refining process.
• the ratio between tensile strength and freeness is improved, i.e., either an increased strength at the same freeness value or same strength at a lower freeness value.
• oven dry pulp is one where pulp has been dried at 100-105 °C to yield a constant weight. Reference is made to TAPPI-test T240 om-93 (1993).
• Conical refiners are of the shallow angle refiners (Jordan), medium angle refiners (Conflo) and wide angle refiners (Claflin).
• the group disk refiners comprises three types, single disc, double disc multi-disc refiners.
• Refining can be done at low consistency (2-6%), medium consistency (10-20%) or high consistency (30-35%). Depending on the requirements of the end product, different choices for optimal consistency processing can be made. Reference is made to Paper and Board Grades, Papermaking Part 1. Stock Preparation and Wet End, Book 18, chapter 4, by the Finnish Paper Engineers' Association and TAPPI (2000 ).
• Processes can be either batch-wise or in a continuous manner, the latter being often preferred due to cost reasons and easier control of quality.
• wood pulp In many cases different types of wood pulp are mixed, such as softwood and hardwood pulp. One of those or both may be refined independently. Often, more refiners are employed in series, to enhance the benefits/energy requirements, to treat the pulp.
• Refining may take place for chemical pulp, mechanical pulp and recycle pulp, all objects of the current invention.
• a low refining is carried out, to ensure a good bulk, softness, absorbancy and brightness.
• a low refining is beneficial for above properties, but negatively impacts the strength properties. Therefore, often wet-and/or dry-strength agents are added. Shopper-Riegler values of between 10 and 30° are often obtained, after refining.
• printability and machine runnability are key parameters.
• the paper must be clean and bright, have the appropriate smoothness, compressibility, ink-penetration capabilities and sufficient strength for the printing operations.
• a minimum opacity is another important feature. Therefore, these papers need good refining control to develop the internal bond strength and to obtain the right level of smoothness and formation for its end use.
• Bleached board grades, used a.o. for packaging frozen foods and liquids, and for paper plates and cups need good stiffness and bulk with proper smoothness and printability. Also internal bond, creasability and dimensional stability are important factors. Therefore sufficient refining to get these properties will also be needed (without decreasing the bulk and stiffness too much).
• Shopper-Riegler values after refining of between 15 and 50° are often needed for these applications.
• the extent of refining can be monitored on-line. Energy input is the most important parameter to determine the extent of refining. Control systems exist to on-line monitor the refining process and adjust energy input according the requirements. Probes to monitor the refiner load, temperature changes, flow/consistency, drainage/freeness (SR), etc. Main process variables include temperature, pH, consistency, additives, pretreatments, production rate, and applied energy.
• Application of the manganese catalyst and hydrogen peroxide to treat the cellulosic fibers can be done at different stages during the fiber treatment/paper making process. This can be either before the mechanical refining process, during the mechanical refining process or after the mechanical refining process.
• pulp that has been bleached in one or more delignification and bleaching stage can be used to treat further to produce tissue, paper or board.
• lignin-containing pulp mechanical pulp
• recycled wood pulp can be used.
• a wet pulp slurry is brought into the paper mill.
• the pulp sheets are first put into a chest and disintegrated to obtain a diluted pulp slurry, which can be further processed.
• chemical pulp is commonly bleached by hydrogen peroxide and/or other bleaching processes using for example ozone or chlorine dioxide.
• Mechanical and recycle pulp are often bleached with hydrogen peroxide to increase brightness of the pulp.
• hydrogen peroxide together with the manganese catalyst can be employed to obtain cellulose that can be treated in the refining process.
• the manganese catalyst and hydrogen peroxide can be added during different stages in the pulp mill.
• a pulp mixer chemicals are added to the pulp, which is then mixed very thoroughly.
• catalyst and hydrogen peroxide could be added to the pulp mixer to achieve treatment of the pulp. This can be done in low consistency mixers (continuous stirred mixers, tower mixers, dynamic mixers or static mixers), medium consistency mixers (peg mixers, high shear mixers) or high consistency mixers, including Kneader and disc-type mixers.
• a steam mixer steam is added to the pulp to increase the temperature of the pulp.
• the catalyst and hydrogen peroxide may also be added to the pulp in the steam mixer.
• the bulk of the pulp bleaching takes place in the pulp bleaching tower, after which the pulp is washed.
• the bleaching towers tend to be large.
• smaller pulp retention pipes are sometimes employed to allow certain bleaching or treatment reactions to occur.
• the pulp is either moving slowly upwards (upflow tower), downwards (downflow tower), or a combination thereof (upflow-downflow tower).
• the treatment by the catalyst and hydrogen peroxide may be much shorter, allowing relatively small treatment towers.
• the pulp treated with chemicals in a previous stage of the treatment process are washed out.
• acidic chlorine dioxide is washed with NaOH solution, to remove alkaline-soluble lignin residues and make the pulp ready for the next stage.
• the manganese catalyst and hydrogen peroxide could be added into an (additional) mixer, making use of its fast reaction kinetics to treat the pulp with the catalyst.
• a pulp storage tower is designed to store pulp to process further after a period of time.
• Such storage tower can be found before the processes where the pulp bleaching stages are taken place or after the final bleaching stage, before e.g. transporting to the paper mill.
• Catalyst and hydrogen peroxide can be added together with the pulp entering this storage tower, allowing a slow treatment process of the pulp.
• a pulper is used to dilute waste paper (deinked pulp) and to add alkaline and hydrogen peroxide for bleaching of deinked pulp.
• the manganese catalyst could be added in this pulper to allow the treatment of deinked pulp by the catalyst.
• the manganese catalyst and hydrogen peroxide can be added to the cellulosic pulp before the refining process in the paper mill, such as in the pulper, high density pulp chest, pulp latency chest, pulp mixing chest or pulp levelling chests.
• the pulper and high density chest are commonly used to prepare dry raw material, half stuff and recyle paper into a pumpable state by addition of water and then mixing with water.
• the pulp mixing chest two or more different types of pulp, optionally refined, are mixed and stored for further processing, such as softwood and hardwood pulp.
• levelling chests the consistency of wood pulp is lowered to desired levels.
• Mechanical pulp is often treated in latency chests to treat the fibers that are distorted (kinked, curled, or twisted). Typically mechanical pulp is diluted to 1-2% consistency, heated to 70-90 °C, agitated for at least 20 minutes, after which it is further processed. Pulp stock chests are, similarly to the pulp storage described above, used to store the wood pulp. Also the other above-mentioned chests are often used to store the wood pulp and ensure a constant flow of pulp to be treated in the subsequent processes. The wood pulp may be shipped from pulp bleaching mills or it may have been produced on site (integrated mill).
• the catalyst/hydrogen peroxide can be added just before the pulp refiner and be allowed to react with the cellulose during the refining process. Due to heat evolution during refining, the additional energy requirement to obtain an optimal treatment effect by the catalyst will be reduced or absent.
• Different refining equipment can be used, which includes beaters; Hollander beaters; shallow-angle conical refiners; medium-angle conical refiners; wide-angle conical refiners; single-disc refiners; double-disc refiners; multi-disc refiners. Reference is made to Paper and Board Grades, Papermaking Part 1. Stock Preparation and Wet End, Book 18, chapter 4, by the Finnish Paper Engineers' Association and TAPPI (2000 ) and C.F. Baker, Tappi Journal, 78, 147, 1995 .
• the catalyst/hydrogen peroxide may be added after the mechanical refining stage, in for example in the pulp blend chest (where the different wood pulp sources are mixed) or pulp stock chest.
• pulp blend chest where the different wood pulp sources are mixed
• pulp stock chest For example mechanical pulp may be treated this way.
• the manganese transition metal catalyst used may be non-deliquescent by using counter ions such as PF 6 - or ClO 4 - , it is preferred for industrial substrates that the transition metal complex is water soluble. It is preferred that the preformed transition metal is in the form of a salt such that it has a water solubility of at least 50 g/I at 20 °C. Preferred salts are those of chloride, acetate, sulphate, and nitrate. These salts are described in WO 2006/125517 .
• R1, R2, R3, and R4 are independently selected from: H and Me.
• the catalyst is derived from a ligand selected from the group consisting 1,4,7-Trimethyl-1,4,7-triazacyclononane (Me 3 -TACN) and 1,2-bis-(4,7-dimethyl-1,4,7-triazacyclonon-1-yl)-ethane (Me 4 -DTNE).
• the preformed transition metal catalyst salt is preferably a dinuclear Mn(III) or Mn(IV) complex with at least one O 2- bridge.
• the level of application of the manganese catalysts can vary depending on the application, but will be typically between 0.0005 and 0.2 kg/t oven-dry pulp (o.d.p.).
• the hydrogen peroxide is provided as an aqueous solution per se, or as peroxy salts, such as, percarbonate, etc. However, for cost reasons liquid hydrogen peroxide is preferred.
• a preferred level of hydrogen peroxide applied is: 0.1 kg/t to 100 kg/t oven dry pulp (o.d.p.), more preferable 0.3 to 50 kg/t o.d.p. and most preferred 0.5 to 25 kg/t o.d.p.
• the reagents are preferably provided in an alkali medium, optimally between pH 8 and 13, the alkalinity of which is preferably provided by sodium hydroxide or sodium carbonate.
• the temperature of the treatment process is preferably between 30°C and 95°C and more preferably between 40°C and 90°C.
• the time of the treatment with the catalyst and hydrogen peroxide is between 1 minute and 4 hours, more preferably between 5 minutes and 3 hours, and most preferably between 10 minutes and 2 hours.
• sequestrants are suitable for use with the present invention. Suitable sequestrants include ethylenediamine tetra-acetate (EDTA), the polyphosphonates such as DequestTM and non-phosphate stabilisers such as EDDS (ethylene diamine di-succinic acid).
• EDTA ethylenediamine tetra-acetate
• DequestTM the polyphosphonates
• EDDS ethylene diamine di-succinic acid
• the sequestrant used in the treatment step with manganese catalyst and hydrogen peroxide is preferably a aminocarboxylate sequestrant or mixtures thereof.
• aminocarboxylate sequestrants ethylenediaminetetraacetic acid (EDTA), N-hydroxyethylenediaminetetraacetic acid (HEDTA), iminodisuccinic acid (IDS), nitrilotriacetic acid (NTA), N-hydroxyethylaminodiacetic acid, diethylenetriaminepentaacetic acid (DTPA), methylglycinediacetic acid (MGDA), and alanine-N,N-diacetic acid.
• DTPA diethylenetriaminepentaacetic acid
• DTPA diethylenetriaminepentaacetic acid
• Phosphonate sequesterents may also be used; a preferred phosphonate sequestrant is Dequest 2066 (Diethylenetriamine Penta(methylene phosphonic acid sodium salt).
• the most preferred concentration of the sequestrant used in the method is 0.01 to 50 kg/ton oven dry pulp in the solution containing the manganese catalyst and hydrogen peroxide, most preferably 0.03 to 20 kg/ton oven dry pulp.
• PE polyethylene
• the PE bottles are put in a pre-heated water bath (62.5°C) for 1 hour and are shaken throughout the bleaching process. Subsequently the pulp mixture is filtrated through a Buchner funnel and washed with copious amounts of demineralised water. Using the filtrate, the H 2 O 2 consumption is measured. The following analyses are carried out on the bleached pulp: kappa number, brightness and intrinsic viscosity.
• the treated pulp was desintegrated (DIN EN ISO 5263-1; 2004-12), beaten (PFI-mill) ( ⁇ NORM EN ISO 5264-2; 2003-05) and the drainability (Schopper-Riegler method, ⁇ NORM EN ISO 5267-1; 2000-10) was tested.
• Table 2 Results of beating and drainability of bleached softwood pulp using [Mn 2 (-O) 3 (Me 3 TACN) 2 ](CH 3 COO) 2 (P1), [Mn 2 (-O) 3 (Me 3 TACN) 2 ](CH 3 COO) 2 and DTPA (P2) and no [Mn 2 (-O) 3 (Me 3 TACN) 2 ](CH 3 COO) 2 (P3) at pH 11.0 at 60°C for 60 minutes.

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• Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Paper (AREA)
• Catalysts (AREA)
• Polysaccharides And Polysaccharide Derivatives (AREA)

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• 2010
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• 2011
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  • 2011-05-09 CN CN201180037116.7A patent/CN103109015B/zh not_active Expired - Fee Related
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