WO1988005372A1 - Procede de production de bandes de fibres multicouche - Google Patents

Procede de production de bandes de fibres multicouche Download PDF

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Publication number
WO1988005372A1
WO1988005372A1 PCT/SE1988/000006 SE8800006W WO8805372A1 WO 1988005372 A1 WO1988005372 A1 WO 1988005372A1 SE 8800006 W SE8800006 W SE 8800006W WO 8805372 A1 WO8805372 A1 WO 8805372A1
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WO
WIPO (PCT)
Prior art keywords
binder
drying
fibers
layers
air
Prior art date
Application number
PCT/SE1988/000006
Other languages
English (en)
Inventor
Bengt Johan Carlsson
Original Assignee
Bengt Johan Carlsson
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 Bengt Johan Carlsson filed Critical Bengt Johan Carlsson
Publication of WO1988005372A1 publication Critical patent/WO1988005372A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B27—WORKING OR PRESERVING WOOD OR SIMILAR MATERIAL; NAILING OR STAPLING MACHINES IN GENERAL
    • B27N—MANUFACTURE BY DRY PROCESSES OF ARTICLES, WITH OR WITHOUT ORGANIC BINDING AGENTS, MADE FROM PARTICLES OR FIBRES CONSISTING OF WOOD OR OTHER LIGNOCELLULOSIC OR LIKE ORGANIC MATERIAL
    • B27N1/00—Pretreatment of moulding material

Definitions

  • the present invention relates to a method of producing multilarninated webs of fibers, which have been formed by beating a ligno ⁇ pellulose-containing material such as wood chips in an atmosphere of steam under pressure. and which have been dried and had added to them a thermosetting binder, the composition of at least one of the layers deviating from the others.
  • the invention will be described here applied to the manu ⁇ facture of laminated wood fiber boards in three layers, using ureaformaldehyde glue as binder, the boards being formed by heat pressing fiber webs with two like surface layers having therebetween a layer deviating in its compo ⁇ sition from the surface layers.
  • the webs When they are heat pressed, the webs are compressed between heated press platens , and are heated successively from the surfaces and inwards.
  • the required press time is determined by the time for heating the central plane of the web to the curing temperature of the binder in the central layer and of the curing time for this.
  • the faces of the surface layers towards the press platens are heated so rapidly during pressing that the binder there has time to harden before full pressing pressure is attained. This results in that the pressed boards have porous surface zones, which are not desirable and there- fore must be ground off.
  • a rapidly curing binder is used for the central layer and a slow curing binder for the surface layers is used to minimize the press time and the thickness of the porous surface zones.
  • the heating time for the central plane of the web can be shortened if the moisture ratio of the surface layers is high and that of the central layer low.
  • the fibers are produced by beating wood chips in a refiner pressurized with stean j and are blown out suspended in steam in a blowing duct to a through-dryer comprising heating apparatus, e.g. a steam battery for heating drying air, a long drying duct, a cyclone and a fan for driving the drying air through these three components in the men- tioned order.
  • heating apparatus e.g. a steam battery for heating drying air, a long drying duct, a cyclone and a fan for driving the drying air through these three components in the men- tioned order.
  • the blowing duct is connected to the drying duct at its end facing towards the heating apparatus, and the fibers are separated after passage through the drying duct from the cooled and moistened air in the cyclone.
  • the drying air is normally vented to the atmosphere from the cyclone.
  • he drying air is taken to a second dry ⁇ ing duct and from this to a second cyclone.
  • This arrange ⁇ ment is known as a two-stage dryer and is used for saving heat energy such that the blower duct from the. refiner is connected to the inlet end of the second drying duct, that in the-second cyclone pre-dried fibers are separated From t h e drying alrv which is then vented to atmosphere, that the pre-dried fibers are taken to the inlet end of the first drying duct, and that after passage through it they are separated in a ready dried state from the drying air in the first cyclone, i.e. the one between the two drying ducts.
  • Ureaformaldehyde binder is often added dissolved in water in a 50 % concentration.
  • the addition can take place after fiber drying in a special bindermixer.
  • Known such mixers give an uneven distribution of the binder on the fibers, which leads to fibers that are coated with too much glue forming wads. If the fibers for the outer layers are treated in this way, the wads show up on the surfaces of the finished boards in the form of dark patches, which decreases the value of the boards.
  • the addition can take place before drying the fibers, e.g. by pumping into the blowing duct.
  • the sur- face patches can be avoided in this way, but the binder is affected when the fibers are transported in the hot air in the dryer, so that to achieve the desired strength values of the boards, the amount of binder must be in ⁇ creased by about 20 % at normal drying temperatures. This increases the total production cost by about 5 %.
  • the fibers After the fibers have been dried and have had binder added to them they are usually collected in tanks, one for the surface and one for the central layer of fibers, from which they are fed to a web-forming station where they -are spread in layers above each other. Two flows are fed out from the tank for surface layer fibers, one being used for forming the lower and the other the upper of the surface layers.
  • the present invention relates to a method in the produc ⁇ tion of multilayer webs of fibers mixed with a thermo- setting binder and having a given moisture ratio, with at least one of the layers having a composition deviating from that of the others, of saving binder and heat energy.
  • investment costs can be reduced by an exten ⁇ sion of the invention.
  • the object of the invention is primarily obtained by using a two-stage dryer, in the first stage of which a fiber flow is dried at a high temperature and thereafter has a binder added to it, a second fiber flow containing binder being dried at a low temperature in the second stage of the dryer.
  • the object of the extension of the invention is achieved by using a refiner from which a fiber flow is blown to the first stage of the dryer j and another fiber flow with an addition of binder is blown to the second stage of the dryer.
  • Figure 1 is a flow diagram for two refiners 1, 2 each connected to a blowing duct 3, 4.
  • Figure 1 also shows heating apparatus 5 for air, a blower 6, a first drying duct 7, a cyclone 8, a second drying duct 9 and a second cyclone 10, connected to each other in the order mentioned.
  • the cyclones 8,10 areprovided with fiber dischargers 11, 12.
  • the blowing ducts 3, 4 are each connected to a drying duct 7, 8 at the duct end illustrated in Figure 1.
  • the fiber discharger 12 at the cyclone 8. is connected to a binder mixer 13, to which a dosing devicel4 is also connected for adding binder.
  • the binder mixer 13 is connected to a tank 15 for intermediate storage of fibers intended for the central layer of the webs.
  • a second dosing devicel6 for binder is connected to the blowing duct 3, opening out in the second drying duct 9.
  • the fiber discharger 11 at the second cyclone 10 is con- nected to a tank 17 for intermediate storage of fibers intended for the surface layers of the webs.
  • Figure 2 illustrates a variant of the arrangement in Fig ⁇ ure 1, with a refiner 18 connected to two blowing ducts 3, 4, identical with those illustrated in Figure 1 and op.n- _ _
  • Discharge of fibers from the tanks 15, 17 to the forming station, and their spreading there in three layers one above the other, is well known technique for one skilled in the art and therefore does not require any closer de ⁇ scription.
  • Fresh air is taken in by the blower 6 through the heating apparatus 5, where it is heated to 160 C and is blown out to the atmosphere after passage through the drying ducts 7, 9 and cyclones 8, 10.
  • Two approximately equally as great fiber flows with the moisture ratio 0.87 are blown through the ducts 3, 4 suspended in about 0.55 kg steam per kg dry fiber, to their respective drying ducts 9, 7.
  • 0.085 kg binder dissolved in an equal amount of water per kg dry fiber is supplied to one duct by the dosing device 16 and the mixture is lead to the second drying duct 9, where it accompanies the drying air to the second cyclone 10.
  • the second half of the fibers is blown in as they are into hot air at 160°C in the first drying duct 7 and ac ⁇ company the air to the cyclone 8, where the fibers are separated and discharged via the fiber discharger 12 to the binder mixer 13.
  • the air is cooled when it leaves the cyclone 8 to 110°C and its moisture ratio is under ' 5 %.
  • the moisture ratio of the fibers is reduced to under 0.01, i.e. they are practically completely dry when they are supplied to the mixer 13.
  • the air departing from the cyclone 8 is taken through the second drying duct 9 and the second cyclone 10, thus being cooled by the accompanying mixture of fibers and binder to 67°C, the moisture ratio adjusting itself to 40 %, which is the state in the departing drying air. Simultaneously, the drying at the moisture ratio 0.13 stops before the fibers in the fiber discharger 11 are supplied to the surface fit ⁇ urs tank 17 with the aid of the fiber discharger 11.
  • the heavily dried fibers have binder added to them with the aid of the device 14, the mix ⁇ ture then being transferred to the tank for central layer fibers.
  • the binder is added in an amount of 0.090 kg dissolved in the same amount of water per kg dry fiber.
  • the moisture ratio increases then to 0.090-0.100.
  • the moisture ratios achieved promote rapid through-heating of the fibers during hot pressing.
  • a rapidly thermosetting binder can be used without inconvenience for the central layer of fibers, since it does not partake in drying, which still further decreases the press time, which decides how large and expensive a press is required.
  • the binder for the surface layer fibers is added be- fore drying, patchy board surfaces are avoided. The desired, extensive, drying out of the central layer fibers cannot be achieved without the air departing from the cyclone 8 being hot and dry, the invention thus results in that the surface layer fibers are dried without cost for heating drying air.
  • the two fiber flows are beaten in a common refiner with associated auxiliary equipment and are subsequently divided for individual processing.
  • the refiner must then, in principle, have double as large a capacity.
  • the pro ⁇ curing cost per unit only increases slightly with capacity, however, and such an arrangement cheapens the plant.
  • Costs for maintenance are reduced at the same time, and larger refiners give better fibers for the same applica ⁇ tion of beating energy.
  • the fiber requirement must be covered by using two refiners, which are each connected to a dryer. If both fiber flows have binder added after drying, it is required that the dry content ratios in the surface layers and the central layer are 0.080 and 0.090. To avoid patches binder is added to the surface layer fibers before drying.. The dry content ratio for the sur- face layers must then be raised. If low temperature dry ⁇ ing is applied here as in Example 1, the ratio for the surface layers must be raised to 0.085 and the binder con ⁇ sumption will be the same as that in Example 1. However, the heat used in the low temperature dryer will so great that it is preferred to increase the input air temperature to 160 C, in spite of then having to increase the dry substance ratio to 0.095-0.100. This method is thus inferior to the one in Example 1, regarding costs for binder as well as costs for dryer heating energy.
  • the invention is not limited to the number of web layers, drying stages, refiners used or the number of blowing lines from a single refiner, but may be varied within the scope of the claims.
  • the binder for the- surface layers can be added to the ma ⁇ terial for beating in front of or in the refiner instead of in the blowing ducts.
  • the invention is not restricted to drying each flow in a single drying stage, and a flow may be pre-dried in one drying stage and finally dried in another, for example, optionally adding binder between the drying stages.
  • the invention can also be varied so that in using multi- component binder, one or more components or other sub ⁇ stances can be added separately and in a way other than that described.

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  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Wood Science & Technology (AREA)
  • Forests & Forestry (AREA)
  • Paper (AREA)
  • Dry Formation Of Fiberboard And The Like (AREA)

Abstract

Le procédé de production de bandes multicouches de fibres avec additions d'un liant à thermoprise consiste à chauffer un matériau contenant de la lignocellulose dans une atmosphère de vapeur sous pression, à ajouter le liant, à sécher et former des bandes en couches superposées, les couches ayant des compositions mutuellement différentes par rapport à la proportion de liant et/ou humidité. Selon l'invention, deux ou plusieurs courants de fibres sont produits et sont séchés individuellement dans une sécheuse à étages multiples de manière à éconimiser de l'énergie thermique, et le liant à thermoprise est ajouté à un ou plusieurs des courants de fibres avant le séchage ainsi qu'à un ou plusieurs courants de fibres après le séchage, également dans le but d'économiser du liant.
PCT/SE1988/000006 1987-01-15 1988-01-15 Procede de production de bandes de fibres multicouche WO1988005372A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8700146-7 1987-01-15
SE8700146A SE454337B (sv) 1987-01-15 1987-01-15 Sett vid framstellning av flerskiktade trefibermattor

Publications (1)

Publication Number Publication Date
WO1988005372A1 true WO1988005372A1 (fr) 1988-07-28

Family

ID=20367183

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/SE1988/000006 WO1988005372A1 (fr) 1987-01-15 1988-01-15 Procede de production de bandes de fibres multicouche

Country Status (3)

Country Link
AU (1) AU1188588A (fr)
SE (1) SE454337B (fr)
WO (1) WO1988005372A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5034175A (en) * 1987-12-16 1991-07-23 Sunds Defibrator Industries Aktiebolag Method and apparatus for manufacturing fiber board sheets
DE4113843A1 (de) * 1991-04-27 1992-10-29 Siempelkamp Gmbh & Co Anlage fuer die aufbereitung und das streuen des streugutes zu streugutmatten im zuge der herstellung von faserplatten mit mittelschicht sowie oberer und unterer deckschicht
EP0873829A1 (fr) * 1997-04-25 1998-10-28 CR&DO B.V. Procédé pour la préparation de composites de cellulose

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE385558B (sv) * 1973-12-22 1976-07-12 Texaco Ag Sett for framstellning av spanplattor med kondensationsharts som bindemedel

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SE385558B (sv) * 1973-12-22 1976-07-12 Texaco Ag Sett for framstellning av spanplattor med kondensationsharts som bindemedel

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5034175A (en) * 1987-12-16 1991-07-23 Sunds Defibrator Industries Aktiebolag Method and apparatus for manufacturing fiber board sheets
DE4113843A1 (de) * 1991-04-27 1992-10-29 Siempelkamp Gmbh & Co Anlage fuer die aufbereitung und das streuen des streugutes zu streugutmatten im zuge der herstellung von faserplatten mit mittelschicht sowie oberer und unterer deckschicht
EP0873829A1 (fr) * 1997-04-25 1998-10-28 CR&DO B.V. Procédé pour la préparation de composites de cellulose
US6365077B1 (en) 1997-04-25 2002-04-02 Cr&Do B.V. Process for preparing cellulosic composites

Also Published As

Publication number Publication date
SE8700146D0 (sv) 1987-01-15
AU1188588A (en) 1988-08-10
SE454337B (sv) 1988-04-25

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