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
  • 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
  • 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
  • D21C9/086—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 with organic compounds or compositions comprising organic compounds

Definitions

• This invention relates to the control of pitch in the manufacture of pulp and paper.
• pitch can accumulate in paper making and also in the manufacture of pulp, causing significant problems.
• “Pitch” is the term used to describe the sticky materials which appear in paper making; these originate from the wood from which the paper is made.
• "pitch” is now used as a general term for all material soluble in organic solvents but not soluble in water, for example the ink or adhesive present in recycled paper.
• the pitch can accumulate at various points in the system. For example, it can block the felt and thus hinder drainage of the paper web. In addition, it can adhere to the wires or drying cylinders causing it to pick holes in the paper. Deposits may also build up at any earlier stage in the papermaking process. When these deposits break loose they may form a defect in the paper such as a spot or a hole. Such defects may even create a weakness in the paper sufficient to induce a breakage in the paper during the production resulting in unappreciated production down-time.
• the present invention provides a method for the control of pitch in an aqueous system used in pulp or paper making which comprises adding to the system or to the pulp making or paper making machinery, a water soluble substantially linear polymer or copolymer possessing recurring units of the formula: where each of R1 and R2 independently represents hydrogen or methyl, X represents hydrogen, -(CH2CH2NH) n H or -(CH2CH2CH2NH) n H, x represents 0 or 1, preferably 1, and n represents 1 to 3, preferably 1, or an acid addition salt or quaternary ammonium salt thereof. It will, of course, be appreciated that the presence of the cyclic structure does not mean that the polymer is crosslinked and is therefore substantially linear.
• a special feature of the products used in the present invention is that they may combine with dissolved anionic material originating from the wood from which the pulp and paper is produced, providing a method of removing these anionic materials thereby lowering the concentration of such materials in the process water.
• Water soluble anionic materials are released from the wood during pulp manufacture. These components interfere with paper production negatively in several ways: they decrease the efficiency of many products used in the papermaking process to alter the character of the paper. Examples of such additives include sizes, wet and dry strength agents and dyes.
• Anionic dissolved materials also reduce the efficiency of retention agents. They limit the extent to which the water system can be closed and they may also lower the quality of the paper such as its strength. Reference is made to TAPPI papermakers Conference 1979 p49-66 which further discusses the significance of anionic dissolved materials.
• the polymers used in the present invention are polymers and copolymers of (meth)allyl amine, vinylamine and di(meth)allyl amine.
• Particular copolymers which may be used are those derived from allylamine and diallylamine as well as those in which the co-monomer is sulphur dioxide or acrylamine.
• the proportion of non-allylic amine monomer in the copolymer desirably does not exceed 50 mole % and preferably not exceed 25 mole %.
• One or more of the nitrogen atoms in the polymer can be quaternised or be in the form of an acid addition salt.
• X represents hydrogen
• the side chain is then terminated by, say, in the case of the monoallylamine units, wherein each of R3, R4 and R5 independently represents hydrogen, a straight or branched chain alkyl or hydroxylalkyl group containing 1 to 5 carbon atoms, an optionally nuclear substituted benzyl group or a cyclohexyl group, or R3 and R4 together with the nitrogen atom form a morpholino or piperidino ring and Y represents an anion, typically a chloride, bromide, iodide, nitrate, bisulphate or dihydrogenphosphate ion.
• R3, R4 and R5 include hydrogen, methyl, hydroxyethyl and hydroxypropyl.
• a particularly preferred quaternary group is trimethylamino.
• X represents -(CH2CH2NH) n H or -(CH2CH2CH2NH) n H the terminal nitrogen atom can be quaternised or be in the form of an acid addition salt in a similar manner with similar substituents and anions.
• Preferred polymers which can be used include poly(allyl amine) hydrochloride, copolymers of allylamine hydrochloride and diallylamine hydrochloride, as well as copolymers of diallylamine hydrochloride and sulphur dioxide.
• the molecular weight of the polymers used will be from 5,000 to 100,000 or 500,000, preferably from 25,000 to 100,000 and especially from 50,000 to 100,000.
• Typical polymers which can be used may have molecular weights of, say, 7,500 to 11,000 or 50,000 to 85,000.
• the polymers used in the present invention can generally be prepared by polymerising an inorganic acid salt of the appropriate monomer, e.g. allylamine hydrochloride, in the presence of a radical- polymerisation initiator possessing an azo group or a cationic nitrogen atom, generally in a polar solvent such as water, an aqueous solution of an inorganic or organic acid, dimethylformamide or dimethyl sulphoxide.
• a typical initiator which can be used is 2,2 ⁇ -diamidinyl-2,2 ⁇ -­azopropane hydrochloride.
• the copolymers can be obtained in a similar manner by radical initiation. Further details regarding the preparation of such polymers can be found in, for example, EP 140309 and 142962. As indicated, the polymers should be substantially linear without crosslinking.
• the polymers in which X represents an aminoalkyl group can generally be obtained from the corresponding polymer in which X is hydrogen.
• cyanoethylation will produce a polymer where X is CH2CH2CN which can be subjected to catalytic hydrogenation with, for example, Raney nickel.
• the starting polymer can be converted to an amine, for example by reaction with ocrylamide giving, in this instance X as CH2CH2CONH2 which can be subjected to a Hoffmann degradation, for example, with hypochlorite and alkali.
• the polymer is generally added to the aqueous system with the furnish containing the paper pulp but it is possible to add it at different points in the system depending on the precise nature of the problem.
• the pulp will generally be present in an amount from 0.5 to 10%, more usually 0.5 to 5% by weight based on the weight of the water.
• the amount of polymer required will, of course, depend to some extent on the nature of the wood or other material used to prepare the paper pulp. Also, some polymer once added will tend to recirculate in the system thus requiring a lower addition rate. In general, however, from 0.1 to 20 ppm of polymer by weight based on the aqueous medium is suitable. Preferably, the amount is 1 to 10 ppm. This corresponds in the normal case to an addition of 10 to 2,000 grams, preferably 100 to 1,000 grams, polymer per tonne fibre.
• the reaction product used in this invention onto a particular part of the pulp- or paper-making machinery such as the wire or press felts.
• the polymer is preferably pre-diluted with water, generally to a concentration below 10% by weight and preferably 1 to 5% by weight.
• biocide in particular a slimicide used in the paper making industry.
• suitable biocides include those in the following classes:
• compositions can optionally be added particularly when the composition is used as a spray, including corrosion inhibitors to protect metal substrates, thickening agents to increase contact times between the composition and the equipment, and surfactants such as amine oxides to improve the wetting of equipment.
• corrosion inhibitors for use in this manner include alkanolamine salts of aryl sulphonamide carboxylic acids, such as the product Hostacor KS1-X available commercially from Hoechst.
• Preferred surfactants for use in this manner include n-alkyl ethoxy dimethylamine oxides where the alkyl has between about 12 and about 18 carbons, such as the product Empigen OY (25% active) available commercially from Albright and Wilson; and lauryl/myristyl dimethylamine oxides, such as the product Empigen OB (30% active) commercially available from Albright and Wilson.
• the polymer is generally compatible with the usual pulp and paper making additives including starch, for example potato or corn starch, titanium dioxide, a de­ foamer such as a fatty acid alcohol, a size, for example a rosin size based on abietic acid, a neutral size based on alkyl ketene dimer or a succinic acid anhydride based size and a wet strength resin such as, if neutral, an epichlorohydrin polyamide or, if acid, a melamine- or urea-­formaldehyde resin.
• starch for example potato or corn starch
• titanium dioxide such as a rosin size based on abietic acid
• a wet strength resin such as, if neutral, an epichlorohydrin polyamide or, if acid, a melamine- or urea-­formaldehyde resin.
• compositions used in the present invention are commercially available, typically as aqueous solutions containing a concentration of 40 to 50 %, especially about 45%, by weight.
• compositions used in the present invention will possess from 1 to 70%, especially 10 to 30%, by weight of the polymer.
• a polyallyl amine hydrochloride was evaluated together with commercially available pitch control agents using essentially the method described in 1977 TAPPI paper makers conference p 23-32 by Ch E Farley. This method is built on TAPPI Standard Method RC324 which is a recognised method for evaluating depositability of pitch.
• the standard pitch solution was prepared as described in the above references.
• a synthetic pitch emulsion/dispersion was prepared by adding one litre volume of various back waters from commercial paper makers at 50°C to the synthetic pitch to reach a 1200 ppm concentration.

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• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Paper (AREA)
• Macromolecular Compounds Obtained By Forming Nitrogen-Containing Linkages In General (AREA)

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• 1987
  • 1987-02-13 GB GB08703304A patent/GB2202872A/en active Pending
• 1988
  • 1988-02-11 FI FI880641A patent/FI880641A/fi not_active Application Discontinuation
  • 1988-02-12 JP JP63028991A patent/JPS63264993A/ja active Granted
  • 1988-02-12 EP EP88301208A patent/EP0280445A1/fr not_active Withdrawn
  • 1988-02-12 NZ NZ223507A patent/NZ223507A/xx unknown
  • 1988-02-12 BR BR8800641A patent/BR8800641A/pt unknown
  • 1988-02-12 AU AU11673/88A patent/AU598099B2/en not_active Ceased
  • 1988-02-12 KR KR1019880001375A patent/KR880010187A/ko not_active Application Discontinuation
  • 1988-02-15 ZA ZA881025A patent/ZA881025B/xx unknown

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