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
  • D21C5/00—Other processes for obtaining cellulose, e.g. cooking cotton linters ; Processes characterised by the choice of cellulose-containing starting materials
  • D21C5/02—Working-up waste paper
  • D21C5/022—Chemicals 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
  • D21C9/08—Removal of fats, resins, pitch or waxes; Chemical or physical purification, i.e. refining, of crude cellulose by removing non-cellulosic contaminants, optionally combined with bleaching
• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21H—PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
  • D21H21/00—Non-fibrous material added to the pulp, characterised by its function, form or properties; Paper-impregnating or coating material, characterised by its function, form or properties
  • D21H21/02—Agents for preventing deposition on the paper mill equipment, e.g. pitch or slime control
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/64—Paper recycling

Definitions

• the invention relates to a process for reducing sticky contaminants in stock systems containing waste paper and in coated broke, and their reuse in the manufacture of papers.
• sticky is understood to mean sticky deposits in the form of organic complexes, which are formed from the waste paper by the agglomeration of disruptive materials which interact with one another. All sticky deposits which are introduced exclusively via the raw materials are referred to as “primary stickies”. If, on the other hand, the formation of the sticky contaminants is brought about only after reaction with additives, then these deposits are referred to as “secondary stickies”.
• the main source for sticky contaminants are adhesives from paper conversion, but also synthetic binders from paper finishing.
• microstickies do not cause any problems in papermaking if they do not agglomerate. In addition, they are then below the visibility limit.
• colloidal, charged particles are formed which counteract agglomeration and deposition.
• the wetting properties of the dispersant are very important in this case, since the “stickies” are generally hydrophobic.
• Known highly cationic fixing agents are polyethylene imine (PEI), polydiallyldimethyl-ammonium chloride (PDADMAC), polyvinyl amine (PVAm), polyaluminium chloride (PAC), polyacrylamide (PAAM) and so on.
• PEI polyethylene imine
• PDADMAC polydiallyldimethyl-ammonium chloride
• PVAm polyvinyl amine
• PAC polyaluminium chloride
• PAAM polyacrylamide
• Solids with a low surface energy exhibit a hydrophobic behaviour and therefore have a high affinity with hydrophobic substances, such as stickies.
• These absorption agents also include, amongst others, the synthetic fibres polyester, polyamide and polypropylene.
• Further adsorption agents used are primarily various types of talc with a specific surface modification and grain size distribution which, because of their hydrophobic and organophilic surface, are capable of depositing on sticky constituents and carrying them out with the paper.
• Adhesive particles encapsulated in this way show a lower tendency to deposition on hot machine parts.
• Combating sticky deposits by means of talc has some drawbacks, however. For example, the system is very sensitive to shear. In addition, talc is difficult to retain and often leads to blinding of the felts. Talc can have a detrimental effect on resin sizing and stabilizes foam.
• Known masking agents for stickies are, amongst others, ethoxilated nonylphenols and ethoxilated dodecylphenols having at least 9 mol ethylene oxide, whose use is limited to dosage rates of 10 ppm because of an extreme tendency to foaming (Wochenblatt für Textilfabrikation (1990) 8, 310 -313).
• graft copolymers of polyalkylene oxide and partially saponified vinylacetate (up to 15% saponification) with a weight ratio of 1:0.2 to 1:10 are used as masking agents, if appropriate in combination with other papermaking aids, it being possible for the polyalkylene oxide to be polyethylene, polypropylene or polybutylene oxide (EP 0571144 A1).
• alkoxylation products which are obtained by reacting alkylene oxides with C 10-22 carbonic acid derivatives and/or C 10-22 carbonic acids, act as masking agents (DE 195 15 273 A1).
• a hydrophilic polymer based on vinyl alcohol which contains some hydrophobic groups such as acetates, propionates, butyrates or oleates and has molecular weights from 2 000 to 125 000 or more (EP 0220001 B1), is used under the commercial name BETZ DETAC® (trademark of the BETZ company) to combat the stickiness of hydrophobic stickies by means of covering them with a hydrophilic film over a wide pH and temperature range.
• BETZ DETAC® trademark of the BETZ company
• This partially saponified polyvinyl alcohol (PVAL) is usually metered in the thick stock area, in order to ensure an adequate reaction time of 20-30 min with the stock to be treated, given good and thorough mixing.
• the necessary dosage rates to combat stickies successfully depend on the type and quantity of the waste paper used. Any influence by other aids is ruled out because of their non-ionic charge (Wochenblatt für Textilfabrikation (1990) 8, 310-313).
• the object of the invention was, therefore, to use the positive properties of partially saponified polyvinyl alcohols as a chemical agent for masking sticky constituents (microstickies) more effectively, from a process engineering point of view, for papermaking which will be less susceptible to disruption and more environmentally friendly with respect to protecting water supplies.
• the point of addition for masking sticky microstickies can therefore be located in the thick stock and also in the thin stock area, depending on the selected preparation and separation technique.
• What is claimed is a process for reducing sticky contaminants, in particular those with a finely divided composition (microstickies) in the preparation of stock systems containing waste paper and of coated broke, characterized in that, after mechanical preparation has been carried out and, if necessary, coarse sticky constituents (macrostickies) have been separated, the stock system has added to it at least one water-soluble organic polyol, in particular a water-soluble polyvinyl alcohol or a mixture of various water-soluble organic polyols, in particular a mixture of various water-soluble polyvinyl alcohols, and bentonite and, if appropriate, further chemical additives and fillers.
• water-soluble organic polyol in particular a water-soluble polyvinyl alcohol or a mixture of various water-soluble organic polyols, in particular a mixture of various water-soluble polyvinyl alcohols, and bentonite and, if appropriate, further chemical additives and fillers.
• the organic polyvinyl alcohols used are water-soluble polymers with proportions of vinyl alcohol or a copolymer of vinyl alcohol and vinyl acetate, which contain hydrophobic groups and are hydrolyzed to more than 70% by weight.
• the organic polyvinyl alcohols are used after the mechanical preparation in proportions from 0.05 to 2% by weight, in particular from 0.1 to 1.0% by weight, based on fibrous material, in combination with bentonites with a high specific surface, preferably alkali modified bentonites, in proportions from 1 to 10% by weight, based on fibrous material.
• the organic polyvinyl alcohols used have a molecular weight from 1 000 to 250 000, preferably 90 000 to 150 000.
• the polyol may also be a water-soluble organic copolymer which contains repeating units of vinyl alcohol and of non-ionic hydrophilic monomers, ionic hydrophilic monomers and/or hydrophobic monomers, the water-soluble organic copolymers comprising at least 20 mol% vinyl alcohol.
• hydrophobic monomers are vinyl acetate, propylene oxide, methacrylate, methylethacrylate, octadecylacrylate, n-octadecylacrylamide, styrene, allyl stearate, vinyl stearate, ethene, propene, n-butene, isobutene, pentene, dodecene, octadecene and vinyl ether higher than methyl.
• non-ionic hydrophilic monomers examples include vinyl pyrrolidone, ethylene oxide and acrylamide.
• the copolymer can have random distribution of the monomer units or various degrees of block formations and/or alternations in the polymer.
• Block formation means that in the copolymer there are regions which are formed by only one of the monomers, while in the case of alternation, a monomer of one sort is always bound to a monomer of the other sort.
• polyvinyl alcohols may also be modified, for example by cationic groups.
• the prepared stock mixture also has added to it cationic fixing agents in proportions from 0.05 to 1% by weight (commercially available), based on fibrous material.
• the stock mixture prepared in this way then had added to it, in a different sequence, various hydrophilicization agents, in particular partially saponified polyvinyl alcohols as masking agents, pigments with a high specific surface, in particular bentonites, as adsorption agents, and various cationic fixing agents of different chemical composition.
• various hydrophilicization agents in particular partially saponified polyvinyl alcohols as masking agents, pigments with a high specific surface, in particular bentonites, as adsorption agents, and various cationic fixing agents of different chemical composition.
• the amount added was 1% by weight (commercially available) in the case of fixing and masking agents and, respectively, 5% by weight (solids) in the case of adsorption agents, based on fibrous material.
• the preparation conditions such as pH and temperature, can be varied over a wide range.
• composite materials from the formed, moist paper sheets are additionally prepared together with aluminium foil by being compressed with one another within 30 seconds in a hot press at 20 bar pressure and 130° C. and later, following cooling and intermediate storage under standard conditions (24 h at 23° C./50% relative humidity), the forces needed to separate the two layers, approximating to the FINAT method, can be determined.
• the stickiness of any residues adhering to the laboratory stirrer, and their elimination by means of a powerful water jet are assessed.
• fixing agents can be just as effective as adsorption or hydrophilicization agents (masking agents).
• talc is generally less beneficial in its effect than bentonite as an adsorption agent (Tables 1 and 3).
• hydrophilicization agents based on partially saponified polyvinyl alcohols belong in the group of additives which bring about the lowest reduction in the COD value in the filtrate, and to some extent even increase it.
• the degree of saponification and further properties of the polyvinyl alcohols used such as molecular weight, viscosity and so on, appear to play a part (Tables 1 and 5).
• a remedy is provided only by the combination of partially saponified polyvinyl alcohol and alkali modified bentonite (Table 2, Variant A3+B2).
• a fixing agent which is additionally used can, if necessary, reduce the COD value still further (Table 2, Variant A3+B2+A1), but in the least favourable case, can also make the separation force and COD values worse again (Table 2, Variant A3+B2+B1). From this it is possible to derive the fact that, depending on the stock and adhesive system used, the optimum fixing agent in this combination of additives has to be found.
• a broke paper had about 5% (solids) of an acrylate contact adhesive added to it, and this stock mixture was well and thoroughly mixed under practical conditions in a technical centre pulper for a period of about 45 min at a moderate consistency of 6% and a temperature of about 60° C. The pH of the stock mixture was adjusted to about 6.

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• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Health & Medical Sciences (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• General Chemical & Material Sciences (AREA)
• Toxicology (AREA)
• Paper (AREA)
• Processing Of Solid Wastes (AREA)

Applications Claiming Priority (2)

Publications (1)

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Country Status (15)

Cited By (4)

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• 2001
  • 2001-01-17 DK DK01900212T patent/DK1268923T3/da active
  • 2001-01-17 CA CA 2391459 patent/CA2391459A1/en not_active Abandoned
  • 2001-01-17 ES ES01900212T patent/ES2225465T3/es not_active Expired - Lifetime
  • 2001-01-17 EP EP01900212A patent/EP1268923B1/de not_active Expired - Lifetime
  • 2001-01-17 PT PT01900212T patent/PT1268923E/pt unknown
  • 2001-01-17 AT AT01900212T patent/ATE274613T1/de not_active IP Right Cessation
  • 2001-01-17 AU AU23908/01A patent/AU781031B2/en not_active Ceased
  • 2001-01-17 WO PCT/IB2001/000034 patent/WO2001053601A1/en not_active Ceased
  • 2001-01-17 JP JP2001553451A patent/JP2003520308A/ja active Pending
  • 2001-01-17 DE DE2001605137 patent/DE60105137T2/de not_active Expired - Fee Related
  • 2001-01-17 KR KR1020027009249A patent/KR20020069258A/ko not_active Abandoned
  • 2001-01-17 NZ NZ518572A patent/NZ518572A/en unknown
  • 2001-01-19 US US09/766,559 patent/US20010023751A1/en not_active Abandoned
• 2002
  • 2002-05-13 ZA ZA200203801A patent/ZA200203801B/xx unknown
  • 2002-07-17 NO NO20023437A patent/NO20023437L/no not_active Application Discontinuation

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