EP0485498B2 - Treatment of fibrous materials - Google Patents

Treatment of fibrous materials Download PDF

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Publication number
EP0485498B2
EP0485498B2 EP90912618A EP90912618A EP0485498B2 EP 0485498 B2 EP0485498 B2 EP 0485498B2 EP 90912618 A EP90912618 A EP 90912618A EP 90912618 A EP90912618 A EP 90912618A EP 0485498 B2 EP0485498 B2 EP 0485498B2
Authority
EP
European Patent Office
Prior art keywords
suspension
fibres
rosin emulsion
aluminium salt
mixture
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
EP90912618A
Other languages
German (de)
English (en)
French (fr)
Other versions
EP0485498A1 (en
EP0485498B1 (en
Inventor
Peter Christopher Robert Street
David Barlow
Michael James Jaycock
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Ciba Specialty Chemicals RC GB Ltd
Original Assignee
Roe Lee Paper Chemicals Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
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Priority claimed from GB898917408A external-priority patent/GB8917408D0/en
Priority claimed from GB898917407A external-priority patent/GB8917407D0/en
Application filed by Roe Lee Paper Chemicals Co Ltd filed Critical Roe Lee Paper Chemicals Co Ltd
Publication of EP0485498A1 publication Critical patent/EP0485498A1/en
Application granted granted Critical
Publication of EP0485498B1 publication Critical patent/EP0485498B1/en
Publication of EP0485498B2 publication Critical patent/EP0485498B2/en
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Classifications

    • 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
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/63—Inorganic compounds
    • D21H17/66—Salts, e.g. alums
    • 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
    • D21H17/00—Non-fibrous material added to the pulp, characterised by its constitution; Paper-impregnating material characterised by its constitution
    • D21H17/62—Rosin; Derivatives thereof
    • 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
    • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
    • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
    • D21H23/04—Addition to the pulp; After-treatment of added substances in the pulp
    • D21H23/06—Controlling the addition
    • D21H23/14—Controlling the addition by selecting point of addition or time of contact between components
    • 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
    • D21H23/00—Processes or apparatus for adding material to the pulp or to the paper
    • D21H23/02—Processes or apparatus for adding material to the pulp or to the paper characterised by the manner in which substances are added
    • D21H23/04—Addition to the pulp; After-treatment of added substances in the pulp
    • D21H23/20—Apparatus therefor

Definitions

  • the present invention relates to a method of sizing fibres particularly but not exclusrvely cellulosic fibres) in an aqueous suspension thereof, the sized fibres being used in the production of paper.
  • the invention also relates to papermaking apparatus.
  • paper as used herein is generic to paper, paperboard, and like fibrous sheet materials which are generally (but not necessarily) of a cellulosic nature.
  • the process for manufacturing paper comprises preparing a suspension of fibres (usually cellulose fibres) from which the paper is to be produced and then passing this suspension along suitable conduit to a papermaking wire or former (hereinafter referred to generically as a wire) on which the suspension is deposited.
  • a papermaking wire or former hereinafter referred to generically as a wire
  • a vacuum is applied to that side of the wire opposite to the side on which the suspension is deposited so that water is drawn through the wire to leave a sheet of the fibres which may then be further dried and processed as required.
  • paper sizing agents are frequently added to the suspension
  • paper sizing agents are rosin emulsions which are used in conjunction with alum (or other simple or polymeric aluminium salts).
  • Further examples are cationic polymer and rosin emulsion mixtures, see for example GB-A-2,141,751. Other combinations of sizes and fixers are also used.
  • the alum is effective under acid conditions to break down the emulsion and cause the rosin to be deposited on the particulate material which constitutes the furnish (i.e. fibres and any filler present).
  • Conventional practice is for the rosin emulsion (pH ca 7) and alum solution (pH less than 3) to be added separately to the suspension of cellulose fibres from which the paper is to be prepared.
  • the additions of rosin and alum solution are made at separate locations along a pipe through which the fibrous stock is flowing.
  • the alum solution is normally added to the pipe considerably upstream of the rosin emulsion.
  • the amount of alum solution added will generally be such as to provide a pH of 5 to 5.5 in the suspension prior to the addition of the rosin emulsion. This degree of acidity is required in the suspension so that the rosin is deposited and retained on the cellulose fibres.
  • this acidic pH may cause problems if the fibrous stock has been produced at least partly from waste paper which incorporates calcium carbonate or when calcium carbonate is added as a filler.
  • the calcium carbonate gives rise to deposits of calcium sulphate.
  • Such deposits build up over a period of time cause blockage of the various lines in the plant and, more importantly, in the apertures of the foraminous wire on which the paper is formed. The process must therefore be periodically shut down so that the blockages may be cleared. Obviously this is a considerable disadvantage.
  • the use of pH conditions close to neutrality is not possible because the rosin is not sufficiently deposited or retained on the fibres. This is a significant disadvantage of sizing with rosin emulsions.
  • AKD alkyl ketene dimer
  • rosin-alum sizing result from the way in which the rosin and alum are introduced into the fibre suspension in the prior process, and that these limitations are overcome by using the procedures set out below which involve rapid mixing of rosin emulsion and alum solution streams and the incorporation of a localised zone (of relatively high concentration) in the fibre suspension.
  • the rosin emulsion/alum solution system is an unstable system in that a mixture of these two components will normally flocculate, but using the rapid mixing procedures set out below a rosin emulsion/alum solution mixture may readily be incorporated in the suspension without problems resulting from flocculation.
  • the fibres to be treated with generally be cellulose fibres and the invention will be specifically described with reference to such fibres. It should however be understood that the invention is also applicable to the sizing of other types of fibres from which paper may be prepared.
  • the fibre suspension will itself be a flowing stream within the stock pipe and the localised zone of the freshly mixed solution of the aluminium salt and rosin emulsion is provided in the fibre suspension stream by the methods described in more detail below.
  • the localised zone Is distributed within such a fibre suspension stream by the flow thereof.
  • the pH of the localised zone in the suspension may as a matter of practice be difficult to measure.
  • the pH of the suspension itself prior to mixture with the rosin emulsion (aluminium salt solution) is easy to measure and it is simply necessary to ensure that a mixture of the rosin emulsion/aluminium salt solutions will be of an acidic pH less than that of the fibre suspension.
  • the localised zone of the mixed rosin emulsion/aluminium salt solution will be at an acidic pH less than that of the fibre suspension.
  • the pH of the fibre suspension after the rosin emulsion aluminium salt has been dispersed therethrough is above 6.5, preferably above 6.7. This ensures that no substantial calcium sulphate deposits (for the case where the fibrous stock has been produced at least partly from calcium carbonate as a filler). Furthermore, operation at these pH values improves drainage through the wire of the paper making machine.
  • rosin emulsions and solutions of aluminium salts to effect sizing of cellulose fibres which are in aqueous suspension provided that the rosin emulsion and aluminium salt solution are continuously provided in the suspension as a freshly mixed localised zone which is at a pH less than that of the suspension. As this zone is distributed throughout the suspension, the rosin emulsion/alum mixture undergoes a pH transition which is effective to cause the rosin to be deposited on the fibres.
  • the method of the invention is most preferably carried out with cellulose fibre suspensions at a pH (before admixture with the rosin emulsion/aluminium salt) of greater than 6 particularly in the range 7 to 8.
  • the invention is also operative at virtually any normal acid pH of at least 6 for rosin sizing and up to say 9.5. This should be contrasted with the prior art process where rosin emulsion and alum solution, added at separate locations in the paper making process, are not effective for sizing cellulose fibres which are in a suspension at a pH greater than 6.
  • the invention thus provides the significant advantage that it may be used for the sizing, with rosin emulsion, of cellulose fibre suspensions which contain calcium carbonate and which are at a pH above 6. With such suspensions, the method of the invention does not give rise to unacceptable deposits of calcium sulphate, calcium aluminium sulphate, and related compounds in the paper machine. Any deposits formed are likely to be of a very small crystal size and are probably included in the final paper.
  • the method of the invention produces paper having an excellent finish on a MG (machine glaze) machine and also an increase in running speed as compared to that obtained with AKD sizes.
  • the aluminium salt used in the method of the invention should preferably be an acidic salt and is most preferably alum. It is however possible to use other aluminium salts that will give rise to polyhydroxy aluminium ions and/or Al (OH) 3 , eg. polyhydroxy aluminium salts such as the compound known as polyaluminium chloride.
  • the amount of the alum solution used will preferably be such as to provide 1-4% by weight of alum (expressed as Al 2 (SO 4 ) 3 . 18H 2 O) dry basis on the fibres.
  • Other aluminium salts may be used in appropriate amounts. For example, we have found that the amount of polyaluminium chloride used in the process may be about 1 / 5 th of the corresponding amount of alum required.
  • the pH of a mixture of the alum solution stream and the rosin emulsion stream should for preference be below 4, more preferably about 3.8.
  • the method of the invention works effectively with a wide variety of rosins, eg. tall oil rosin and gum rosin.
  • the rosin will usually have a melting point of 70-85° C.
  • the rosin emulsion will generally comprise 20-50% solids and be used in an amount so as to provide 0.1-2% by weight (dry basis) on the fibres.
  • the alum solution and rosin emulsion are intensively mixed together immediately prior to the injection of the mixture into the stock pipe along which the suspension of cellulose fibres is flowing.
  • the mixing is effected by passing the rosin emulsion and alum solution in opposite directions, and under turbulent flow conditions, along a tube which has intermediate its end an outlet communicating with the interior of the stock pipe.
  • This mixing tube may, for example, comprise a T-plece with the resin emulsion and alum solutions being directed under turbulent flow conditions) in opposite directions along the "bar" of the T and the resultant mixture being passed along the "stem" of the T into the stock pipe.
  • the rosin emulsion/alum solution mixture is able to be incorporated in the fibre suspension without flocculation problems occurring.
  • the localised zone of the mixture of rosin emulsion and alum solution is provided in a cellulose fibre suspension which is in the form of so-called thick stock, ie. a suspension which generally contains about 3% by weight of the cellulose fibres rather than the thin stock (which will generally comprise about 1% by weight of the fibres), although this does depend on the degree of dilution in going from thick to thin stock.
  • the invention is however applicable to the treatment of fibre suspensions containing greater or lesser amounts of fibres. However, for preferance the suspension will comprise 0.1%-10% by weight of fibres, more preferably 0.2-5%.
  • Fig. 1 is a plot of total dissolved aluminium (A t ) vs pH and shows the stability region of freshly precipitated Al(OH), based on the assumption that the only other species present are Al(OH) 4 - , Al(OH) 2+ , its dimer Al 2 (OH) 2 4+ , Al 13 (OH) 34 5+ , and Al 7 (OH) 17 4+ , as well as the uncomplexed ion Al 3+ .
  • Fig. 1 is a thermodynamic diagram and may be thought of as corresponding to equilibration times longer than those normally encountered in the sizing process in a paper mill.
  • the mixture of resin emulsion and alum solution which forms the localised zone in the cellulose fibre suspension preferably has a pH less than 4.
  • the aluminium concentration is normally greater than 10 -4 mol dm -3 and thus greater than the minimum value of Al T at which Al(OH) 3 precipitate will form.
  • the final position on the solubility diagram may be inside the region corresponding to Al(OH) 3 or in the Al(OH) 4 - region, where the concentration of polynuclear complexes will be vanishingly small, and there would be no precipitated Al(OH) 3 .
  • the point at which the localised zone of rosin emulsion/alum solution mixture is provided is moved near to where the sheet is formed, it is believed that there will not be time for the Al(OH) 3 to redissolve or for the polynuclear species to be converted to Al(OH) 4 - , so that satisfactory sizing performance can be achieved.
  • thermodynamic (and not a kinetic) diagram representing the position at equilibrium which may take some time to achieve.
  • Al(OH) 3 and polymeric aluminium hydroxy species (initially formed) persist long enough for sizing to take place.
  • Fig. 2 is a very schematic illustration of the basic steps involved in papermaking.
  • a tank 100 there is prepared a suspension of cellulose fibres which are then passed along conduit 101 to a head box 102 from which the suspension is deposited on a wire 103 of a Foudrinier machine.
  • Vacuum boxes 104 serve to draw water from the layer of fibres on the wire.
  • conduit 101 shown in Fig. 2 is intended very schematically to represent the connection between the tank 100 and the head box 102.
  • the conduit arrangement is likely to be rather more complicated that that illustrated and may include a thick stock line and a thin stock line as well as pumps for moving the suspension.
  • a mixing arrangement 105 at some point along the conduit for providing therein a localised zone of freshly mixed streams of rosin emulsion and alum solution.
  • Various examples of such mixing arrangements are illustred in Figs. 3-8.
  • Figs. 3-8 show various mixing arrangements for providing the localised zone of the mixture of rosin emulsion and alum solution in a conduit 1 along which an aqueous cellulose fibre suspension is flowing in the direction of arrow A.
  • the conduit 1 will for preference be the thick stock pipe in each of Figs. 3-8 the rosin emulsion is considered to be supplied in the direction of arrow B along a pipe, or pipe section, referenced as 2 and the alum solution is supplied in the direction of arrow C along a pipe, or pipe section, referenced as 3.
  • the mixing device of Fig. 3 is the preferred device for use in the invention and is a T-piece arrangement in which the rosin emulsion and alum solution streams impinge upon each other so that the mixture exits in the direction of arrow D along the stem of the T which is provided in the centre of the conduit 1.
  • the mixture enters conduit 1 as a localised zone at a pH of less than 4, which then becomes dispersed throughout the cellulose fibre suspension and thus undergoes the necessary pH transition.
  • the pH of the fiber suspension up stream of the T-piece may be about 7-8 whereas down stream of the T-piece (and after distribution of the rosin emulsion/alum solution in the suspension (the pH may be about 6.7.
  • the flow of rosin emulsion and alum solution along the respective pipe sections 2 and 3 will be turbulent flow as this will promote more intensive and rapid mixing of the two streams. Whether the flow inside the mixer is laminar or turbulent is dependent on the Reynolds' number (Re). For a long smooth straight pipe the critical value of (Re) is usually taken as 2000, and this value may be used as a rough guide in calculating the diameters needed to produce the preferred turbulent flow conditions inside the mixer. A more detailed consideration of the conditions governing turbulent flow is given in Appendix a, and the design of a T-piece for mixing rosin emulsion and alum solution is given in Appendix b.
  • Fig. 4 shows a modification of Fig. 3 in which the stem of the T is omitted and the rosin emulsion/alum solution mixture simply issues through an orifice 4 into the stock pipe 1.
  • the mixing devices shown in Figs. 3 and 4 may be manufactured from tubing which is of a diameter specifically selected (or produced) to give the required turbulent flow conditions.
  • the T-piece can however also be made from standard size tubing and have its bore reduced by means of inserts as shown in Figs. 5-6. These inserts may be bored with the right sized holes to form T-piece type configurations (Figs. 5 and 6).
  • Fig.7 shows a further embodiment of T-piece type mixing device.
  • a T-piece connector has internally threaded ends such that tubes 2 and 3 for supplying rosin emulsion and alum solution respectively may be mounted therein as shown.
  • a tube may be mounted in the stem of the T through which the mixture of alum solution and rosin emulsion exits into the suspension of cellulose fibres. The length of this latter tube may be selected having regard to the length of time for which it is desired to keep the alum solution and rosin emulsion in contact with each other before they enter the cellulose fibre suspension.
  • inserts may be provided in the T-piece connector as shown.
  • the illustrated insert may be formed from a single piece of tubing (one end of which is closed) simply by boring a hole transversely through the tube adjacent its closed end to obtain the configuration shown. This insert may then simply be inserted into the T-piece connector along the stem thereof.
  • Fig. 8 shows what may be considered as a virtual T-piece, where the mixing zone is created by the injections streams, and the pipe work is somewhat curtailed.
  • Fig. 8 shows the two pipes 2 and 3 at right angles to the walls of the conduit 1 injecting into the middle of the cellulose fibre stream so that the injected flows impinge on each other.
  • the arrangement of Fig. 8 is believed to be less efficient in mixing, as might be expected, and less effective from the point of view of sizing paper making performance than the T-piece of Figs. 3 and 4.

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  • Chemical & Material Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Paper (AREA)
EP90912618A 1989-07-29 1990-07-30 Treatment of fibrous materials Expired - Lifetime EP0485498B2 (en)

Applications Claiming Priority (5)

Application Number Priority Date Filing Date Title
GB898917408A GB8917408D0 (en) 1989-07-29 1989-07-29 Paper sizing
GB898917407A GB8917407D0 (en) 1989-07-29 1989-07-29 Papermaking
GB8917407 1989-07-29
GB8917408 1989-07-29
PCT/GB1990/001176 WO1991002119A1 (en) 1989-07-29 1990-07-30 Treatment of fibrous materials

Publications (3)

Publication Number Publication Date
EP0485498A1 EP0485498A1 (en) 1992-05-20
EP0485498B1 EP0485498B1 (en) 1996-09-18
EP0485498B2 true EP0485498B2 (en) 1999-12-08

Family

ID=26295679

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90912618A Expired - Lifetime EP0485498B2 (en) 1989-07-29 1990-07-30 Treatment of fibrous materials

Country Status (7)

Country Link
EP (1) EP0485498B2 (es)
AU (1) AU6186490A (es)
CA (1) CA2059529C (es)
DE (1) DE69028631T2 (es)
ES (1) ES2094161T5 (es)
GB (1) GB9201848D0 (es)
WO (1) WO1991002119A1 (es)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2292158B (en) * 1994-07-26 1998-12-09 Roe Lee Paper Chemicals Compan Sizing method
FI108802B (fi) 1998-02-26 2002-03-28 Wetend Technologies Oy Menetelmä ja laite kemikaalin syöttämiseksi nestevirtaan sekä paperikoneen syöttöjärjestelmä
US7234857B2 (en) 1998-02-26 2007-06-26 Wetend Technologies Oy Method and apparatus for feeding a chemical into a liquid flow
RU2200217C2 (ru) * 2001-03-11 2003-03-10 Хабаровский государственный технический университет Устройство для введения полимерных добавок в бумажную массу
US6543382B1 (en) * 2002-02-08 2003-04-08 Delaval, Inc. Side outlet milking claw
FI115148B (fi) * 2003-10-08 2005-03-15 Wetend Technologies Oy Menetelmä ja laite kemikaalin syöttämiseksi nestevirtaan
US20070133346A1 (en) * 2005-12-14 2007-06-14 Tommy Jacobson Mixing of chemicals into a thin stock pipe
DE102010028574A1 (de) * 2010-05-05 2011-11-10 Voith Patent Gmbh Mischanordnung
DE102010028577A1 (de) * 2010-05-05 2011-11-10 Voith Patent Gmbh Verfahren zur Zumischung einer Chemikalie zu einem Prozessstrom
CN103930618B (zh) * 2011-11-14 2016-06-08 凯米拉公司 Akd组合物以及纸和纸板的生产

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2041285A (en) * 1933-09-28 1936-05-19 Cew Judson A De Paper sizing
GB2141751B (en) * 1983-06-03 1987-07-08 Roe Lee Paper Chemicals Compan Sizing compositions

Also Published As

Publication number Publication date
WO1991002119A1 (en) 1991-02-21
DE69028631T2 (de) 1997-02-27
EP0485498A1 (en) 1992-05-20
AU6186490A (en) 1991-03-11
DE69028631D1 (de) 1996-10-24
ES2094161T5 (es) 2000-06-16
ES2094161T3 (es) 1997-01-16
CA2059529C (en) 2001-11-27
EP0485498B1 (en) 1996-09-18
GB9201848D0 (en) 1992-03-18
CA2059529A1 (en) 1991-01-30

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