WO2001051702A1 - Traitement thermique de pate a papier - Google Patents

Traitement thermique de pate a papier Download PDF

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Publication number
WO2001051702A1
WO2001051702A1 PCT/SE2001/000032 SE0100032W WO0151702A1 WO 2001051702 A1 WO2001051702 A1 WO 2001051702A1 SE 0100032 W SE0100032 W SE 0100032W WO 0151702 A1 WO0151702 A1 WO 0151702A1
Authority
WO
WIPO (PCT)
Prior art keywords
pulp suspension
pulp
temperature
paper
proceeding
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.)
Ceased
Application number
PCT/SE2001/000032
Other languages
English (en)
Inventor
Anders Leandersson
Carl HÅKANSSON
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.)
Valmet AB
Original Assignee
Metso Paper Karlstad AB
Valmet Karlstad AB
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
Application filed by Metso Paper Karlstad AB, Valmet Karlstad AB filed Critical Metso Paper Karlstad AB
Priority to AU2001227218A priority Critical patent/AU2001227218A1/en
Publication of WO2001051702A1 publication Critical patent/WO2001051702A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • 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
    • D21C9/007—Modification of pulp properties by mechanical or physical means
    • 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
    • D21H11/00—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only
    • D21H11/16—Pulp or paper, comprising cellulose or lignocellulose fibres of natural origin only modified by a particular after-treatment

Definitions

  • the present invention relates to a method for treating a chemically produced pulp suspension of a material containing lignocellulose after beating of said pulp suspension. Especially it relates to the treatment of a pulp suspension intended for production of an end product with high porosity, i.e. with low Gurley number, preferably for production of craft sack paper.
  • the invention is also applicable to pulp suspensions for other products.
  • the invention also relates to a paper or paper board product produced according to the method of the invention.
  • a high bulk i.e. a low density is often aimed at, e.g., for porous sheets.
  • porosity Another important parameter for such products, especially craft sack paper, is porosity.
  • High porosity is aimed at because it implies high air permeability (for example measured in Gurley number), a low Gurley number corresponding to a high air permeability.
  • Gurley number for example measured in Gurley number
  • the reason for aiming at low Gurley numbers for especially craft sack paper is that when the sacks, often industrial sacks, are filled a certain amount of air comes along with the material into the sack being filled. Especially at industrial filling of sacks its important that these amount of air can find its way out very fast.
  • a problem in connection with wet pressing of a paper or paper board web is that conventional roll pressing results in both increased density and reduced porosity as the dry solids content is increased. If the web is heated in the press section, e.g. steam boxes, during very short periods of time - typically less than 50 ms - the dry solids content is certainly increased but the bulk deteriorates, i.e. the density increases.
  • the press section e.g. steam boxes
  • One object of the invention is in the production of a paper or paper board web from a chemically produced pulp suspension, to achieve reduced density and/or increased porosity, by comparison with a corresponding paper or paper board web produced from a reference pulp, i.e. a corresponding pulp suspension not treated according to the invention.
  • this is achieved by heating a beated pulp suspension in a heat treating step to a treating temperature of at least 60° C yielding a reduced density and/or increased porosity in a paper or paper board product produced from the treated pulp suspension.
  • the heating continues just until the intended treating temperature has been attained after which the pulp suspension is lead further in the line.
  • the suitable treating time at said treating temperature is at least 30 seconds, preferably at least 1 minute and more preferably 1-60 minutes and most of all 1-30 minutes.
  • the surprising result can be used for increased quality when the product is craft sack paper.
  • the grammage can be reduced thanks to the reduced density.
  • at maintained level of density/bulk at least some percent (e.g. about 1 %) higher dry solids content can be obtained before the end drying, which may be said to correspond to some percent (e.g. about 4 %) increase of the production and corresponding lower specific steam consumption.
  • US 4,431,479 it is indeed known to heat treat a pulp suspension after mechanic treatment at high consistency.
  • the process described therein differ considerably from the invention concerning both the type of product/pulp, the object of the treatment and the way the treatment is carried out.
  • the heat treatment which preferably is carried out at atmospheric pressure by heating with steam, can be carried out both at low consistency and high consistency. Accordingly, in a first embodiment of the invention the pulp suspension is heat treated at a consistency of 1-12 %, preferably 2-8 %.
  • the pulp suspension is instead heat treated at a consistency of 10-50 %, preferably 10-40 % and more preferred 13-40 %.
  • the latter case may have economical advantages: the less water the pulp suspension contains the less steam is consumed to heat the pulp to desired temperature.
  • a high consistency in the treatment has the advantage that the treatment, if desired, may take place directly at the consistency of the pulp after the mechanical treatment of the fibres at high consistency, so called HC-beating, i.e. at least 20 %, preferably 25-40 % and more preferably 25-35 %.
  • HC-beating i.e. at least 20 %, preferably 25-40 % and more preferably 25-35 %.
  • less removal of water is needed after HC- beating before heat treatment at high consistency.
  • the beating is carried out as HC-beating, at least when the product is craft sack paper.
  • the beating is carried out to a beating degree of 15-25° Shopper-Riegler, preferably under 20° Shopper-Riegler.
  • the pulp suspension is produced according to the sulphate method (craft) or modifications of it.
  • the pulp suspension is intended to be used in the end product craft sack paper showing high porosity, i.e., a low Gurley number, preferably a Gurley number under 20 s, more preferably a Gurley number under 10 s and most preferably a Gurley number under 5 s.
  • the grammage of the product is typically 60-120 g/m 2 .
  • the pulp suspension constitutes of pulp for craft sack paper, or more specifically of long-fibred chemical pulp of soft wood. As the craft sack paper is unbleached, the pulp suspension shows a relatively high kappa number during the heat treatment.
  • the heating according to the invention is carried out preferably at atmospheric pressure, the steam having a temperature of 100° C. Also a pressurised method may be possible, the pressure of the treatment being above 1 bar (abs) and the temperature being above 100° C. Preferably, the pulp suspension is stirred mechanically during the heating.
  • the pulp suspension is diluted with white water as required, suitably to a consistency of under 2 %, preferably under 1 %, suitably some tenth %, and is led to a headbox for formation of a web on a wire.
  • the temperature of the pulp suspension can be maintained at the treating temperature or reduced by at most 20° C compared to a temperature during the treatments according to the invention, preferably with at most 5-15° C.
  • the web is pressed and dried in a conventional way after formation of the wire, as well modern as older press and drying methods being possible to use.
  • Fig. 1 shows schematically a flow diagram for a possible accommodation plan of the apparatus for realization of the invention
  • Fig. 2 shows a diagram over the density as a function of dry solids content for a test series according prior art
  • Fig. 3 shows a diagram over density as a function of dry solids content for a first test series according the present invention
  • Fig. 4 shows a diagram over density as a function of dry solids content for a second test series according to the present invention
  • Fig. 5 shows a diagram over porosity as a function of dry solids content for said second test series according to the present invention.
  • Fig. 1 shows a possible accommodation plan of the apparatus for a embodiment of the invention according to production of craft sack paper.
  • Part number 1 in Fig. 1 shows an atmospheric compensation tank to which a pulp suspension 2 is led after beating 12.
  • a pulp suspension 2 is led after beating 12.
  • steam 3 having a temperature of 100° C for heating the pulp to about 90° C under mechanic stirring.
  • the dwell time in the compensation tank 1 is about 15 minutes.
  • the pulp suspension is diluted with process liquid 4 having a temperature that is 0-20° C below the temperature in the compensation tank, the liquid consisting preferably of so called white water.
  • the temperature of the pulp suspension decreased by as most 20° C when the consistency is regulated to about 3-4 %.
  • the pulp suspension is pumped 5 to a so called machine chest 6 acting as a buffer and to which possible chemicals are added.
  • the pulp suspension is pumped 7 further to be subsequently additionally diluted 8 with white water from a white water tank 9 provided with white water 13 from the wire tank 14.
  • the consistency is regulated at the dilution 8 to about 0,2 % and also the flow of pulp is regulated after which the pulp suspension is pumped by a mixing pump 10 to further be led to a headbox 11.
  • the pulp suspension is formed from the headbox 11 on the wire (not shown) in order to the be led further through wet press section and drying.
  • EXAMPLE 1 (prior art)
  • a paper web was heat treated with low pressure steam by means of two steam boxes, between first and second press, and before couch roll.
  • Line 1 in Fig. 2 constitutes the reference showing how the density of the end product is dependent of dry solids content at the pressing of the web without treatment with headboxes. In principle the density increases proportionally to the dry solids content.
  • the line 2 shows how the density in the end product is dependent of the dry solids content at the pressing of the web including the treatment by means of steam boxes. For all test points the white water temperature was the same.
  • line 2 constitutes a continuation of line 1, i.e. the density continues to increase with increasing dry solids contents which is achieved by means of treatment with headboxes. Accordingly, higher dry solids contents in the press section is achieved at the price of higher density in the end product.
  • a pulp suspension of craft sack paper pulp, produced by means of the sulphate method was treated according to the invention.
  • Line 1 in Fig. 3 shows how the density depends on the dry solids content of a reference sample in which the pulp had a conventional temperature of about 40° C after the beating.
  • the pulp was diluted with white water having a temperature of 44° C, formed on the wire by means of the headbox, pressed and dried.
  • the pulp suspension has been treated with steam to a temperature of about 60° C after which the pulp was diluted with white water having a temperature of about 50° C, formated on a wire, pressed and dried.
  • the heat treatment may be carried out in many other ways than with direct steam, for example by use of indirect steam or in other ways.
  • the process is not limited to be atmospheric.
  • the pulp suspension may also be sulphite pulp, at least if the product is not craft sack paper.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Wood Science & Technology (AREA)
  • Paper (AREA)

Abstract

Procédé de traitement d'une suspension (2) de pâte, produite chimiquement, d'une matière contenant de la lignocellulose, après raffinage (12) de cette suspension de pâte. Ladite suspension (2) est chauffée lors d'une phase de traitement par chauffe à une température de traitement d'au moins 60 °C, ce qui permet d'obtenir un produit papier ou carton à densité réduite et/ou à porosité accrue, à partir de la suspension de pâte ainsi traitée.
PCT/SE2001/000032 2000-01-10 2001-01-10 Traitement thermique de pate a papier Ceased WO2001051702A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU2001227218A AU2001227218A1 (en) 2000-01-10 2001-01-10 Heat treatment of paper pulp

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE0000031A SE515722C2 (sv) 2000-01-10 2000-01-10 Värmebehandling av mald, kemiskt framställd massasuspension
SE0000031-5 2000-01-10

Publications (1)

Publication Number Publication Date
WO2001051702A1 true WO2001051702A1 (fr) 2001-07-19

Family

ID=20278033

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE2001/000032 Ceased WO2001051702A1 (fr) 2000-01-10 2001-01-10 Traitement thermique de pate a papier

Country Status (3)

Country Link
AU (1) AU2001227218A1 (fr)
SE (1) SE515722C2 (fr)
WO (1) WO2001051702A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1749935A2 (fr) 2005-08-01 2007-02-07 Voith Patent GmbH Procédé de fabrication de papier tissu
WO2015189800A1 (fr) * 2014-06-13 2015-12-17 Stora Enso Oyj Procédé de fabrication d'au moins une couche d'un produit de papier ou carton et produit de papier ou carton
EP3088606A1 (fr) * 2015-04-29 2016-11-02 BillerudKorsnäs AB Papier d'ensachage brun désintégrable

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4409065A (en) * 1977-01-26 1983-10-11 Technopulp A.G. Kraft paper
US4431479A (en) * 1982-05-11 1984-02-14 Pulp And Paper Research Institute Of Canada Process for improving and retaining pulp properties
WO1999002772A1 (fr) * 1997-07-09 1999-01-21 Assidomän AB Papier kraft et son procede de fabrication

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4409065A (en) * 1977-01-26 1983-10-11 Technopulp A.G. Kraft paper
US4431479A (en) * 1982-05-11 1984-02-14 Pulp And Paper Research Institute Of Canada Process for improving and retaining pulp properties
WO1999002772A1 (fr) * 1997-07-09 1999-01-21 Assidomän AB Papier kraft et son procede de fabrication

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1749935A2 (fr) 2005-08-01 2007-02-07 Voith Patent GmbH Procédé de fabrication de papier tissu
EP1749935A3 (fr) * 2005-08-01 2009-05-13 Voith Patent GmbH Procédé de fabrication de papier tissu
WO2015189800A1 (fr) * 2014-06-13 2015-12-17 Stora Enso Oyj Procédé de fabrication d'au moins une couche d'un produit de papier ou carton et produit de papier ou carton
US20170121913A1 (en) * 2014-06-13 2017-05-04 Stora Enso Oyj Process for producing at least one ply of a paper or paperboard product and a paper or paperboard product
US9988765B2 (en) 2014-06-13 2018-06-05 Stora Enso Oyj Process for producing at least one ply of a paper or paperboard product and a paper or paperboard product
EP3088606A1 (fr) * 2015-04-29 2016-11-02 BillerudKorsnäs AB Papier d'ensachage brun désintégrable
WO2016173684A1 (fr) * 2015-04-29 2016-11-03 Billerudkorsnäs Ab Papier pour sac brun désintégrable

Also Published As

Publication number Publication date
AU2001227218A1 (en) 2001-07-24
SE0000031D0 (sv) 2000-01-10
SE515722C2 (sv) 2001-10-01
SE0000031L (sv) 2001-07-11

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