CA1190372A - Process for the manufacture of lignocellulosic material fibreboard - Google Patents
Process for the manufacture of lignocellulosic material fibreboardInfo
- Publication number
- CA1190372A CA1190372A CA000382883A CA382883A CA1190372A CA 1190372 A CA1190372 A CA 1190372A CA 000382883 A CA000382883 A CA 000382883A CA 382883 A CA382883 A CA 382883A CA 1190372 A CA1190372 A CA 1190372A
- Authority
- CA
- Canada
- Prior art keywords
- fibre
- resin
- lying
- urea
- binder 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
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L61/00—Compositions of condensation polymers of aldehydes or ketones; Compositions of derivatives of such polymers
- C08L61/20—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
-
- 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
- B27N3/00—Manufacture of substantially flat articles, e.g. boards, from particles or fibres
- B27N3/002—Manufacture of substantially flat articles, e.g. boards, from particles or fibres characterised by the type of binder
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L97/00—Compositions of lignin-containing materials
- C08L97/02—Lignocellulosic material, e.g. wood, straw or bagasse
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L61/00—Compositions of condensation polymers of aldehydes or ketones; Compositions of derivatives of such polymers
- C08L61/20—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen
- C08L61/22—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with acyclic or carbocyclic compounds
- C08L61/24—Condensation polymers of aldehydes or ketones with only compounds containing hydrogen attached to nitrogen of aldehydes with acyclic or carbocyclic compounds with urea or thiourea
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L91/00—Compositions of oils, fats or waxes; Compositions of derivatives thereof
- C08L91/06—Waxes
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Life Sciences & Earth Sciences (AREA)
- Organic Chemistry (AREA)
- Wood Science & Technology (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Materials Engineering (AREA)
- Manufacturing & Machinery (AREA)
- Forests & Forestry (AREA)
- Dry Formation Of Fiberboard And The Like (AREA)
- Paper (AREA)
- Stringed Musical Instruments (AREA)
- Porous Artificial Stone Or Porous Ceramic Products (AREA)
- Treatments For Attaching Organic Compounds To Fibrous Goods (AREA)
- Reinforced Plastic Materials (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A process for the manufacture of lignocellulosic material fibreboard wherein the fibre impregnation step takes place when the latter is wet, at the delivery from the grinder operating at high pressure and passage to the dryer. This impregnation is effected with a binder mixture having a resin solids content lying between 40% and 45% and a viscosity of less than 15 cps, prepared from a tack free urea-formaldehyde resin having a solids content of 60% to 70%, a viscosity at 25°C lying between 150 and 300 cps and a free formaldehyde value of less than 1%.
A process for the manufacture of lignocellulosic material fibreboard wherein the fibre impregnation step takes place when the latter is wet, at the delivery from the grinder operating at high pressure and passage to the dryer. This impregnation is effected with a binder mixture having a resin solids content lying between 40% and 45% and a viscosity of less than 15 cps, prepared from a tack free urea-formaldehyde resin having a solids content of 60% to 70%, a viscosity at 25°C lying between 150 and 300 cps and a free formaldehyde value of less than 1%.
Description
'~ 3~
1~ ~ S C K 1 P ~ 1 O N
This inventio~ relate~ to a proce~ :eor the ~anufacture of l~g~ocelllAlo~ic material ~ibreboard, co~pri~g the ~tep~
of prepar~g a binder laixture, providi~,g a li~ocellulosic material" ~hredding ~aid material9 dige~t~ng ~aid ~hredded materi~, grinding the re~ulting product, impregnati~g 1;he fibre with said bi~der ~ture~ dr~ri~g the fabre ~d pres~g it .
The ~urrent practice i~ for the mar~ufactlarer of this type OI fibreboard to u~e a binder m~cture obtairled from a urea-fo~naldehyde re~in prep~red i~ tur~ :$rom a commercially available urea-formaldehyde preconden~ate~
Urea~-formaldehyae preco~den~ates are commercial high coneentration formaldehyd@ solution~ ~tabilised with ur~a, A re~in i~ prepare~ ~rom the preconde~sate~ by reaction with urea (or urea and melam me) and this resi~ i~ used to prepare a bi~der mixture ~ith which the lig~ooellulo~ic material fibre i~ impregnated (~ormally soft woods are used, such a~ pmeg eucalyptu~9 poplar~ etc., but other ~oods and products such as ~agas~e9 3traw9 etc~ may be used) and the impregnated fibre i~ tra~ferred thereafter to a pre~s, ~here the ~ibreboard i~ prepared by heat (by hot fluid~ flowing through the pres~ plate~ or by eleetrical s~te~s: elements9 high ~r~uency) and pre~ureO Ne~ertheles~, ~e~er~l disadv~nta~
ge~ are encountered ~ thi~ proces~.
1~ ~ S C K 1 P ~ 1 O N
This inventio~ relate~ to a proce~ :eor the ~anufacture of l~g~ocelllAlo~ic material ~ibreboard, co~pri~g the ~tep~
of prepar~g a binder laixture, providi~,g a li~ocellulosic material" ~hredding ~aid material9 dige~t~ng ~aid ~hredded materi~, grinding the re~ulting product, impregnati~g 1;he fibre with said bi~der ~ture~ dr~ri~g the fabre ~d pres~g it .
The ~urrent practice i~ for the mar~ufactlarer of this type OI fibreboard to u~e a binder m~cture obtairled from a urea-fo~naldehyde re~in prep~red i~ tur~ :$rom a commercially available urea-formaldehyde preconden~ate~
Urea~-formaldehyae preco~den~ates are commercial high coneentration formaldehyd@ solution~ ~tabilised with ur~a, A re~in i~ prepare~ ~rom the preconde~sate~ by reaction with urea (or urea and melam me) and this resi~ i~ used to prepare a bi~der mixture ~ith which the lig~ooellulo~ic material fibre i~ impregnated (~ormally soft woods are used, such a~ pmeg eucalyptu~9 poplar~ etc., but other ~oods and products such as ~agas~e9 3traw9 etc~ may be used) and the impregnated fibre i~ tra~ferred thereafter to a pre~s, ~here the ~ibreboard i~ prepared by heat (by hot fluid~ flowing through the pres~ plate~ or by eleetrical s~te~s: elements9 high ~r~uency) and pre~ureO Ne~ertheles~, ~e~er~l disadv~nta~
ge~ are encountered ~ thi~ proces~.
2 ~ 37~
In the ~ir~t place, there i~ a hi,~h degree of in~tabilityp ~i~ce th~ resin rem~i~ ~ table f`or a period of le~ th~ 48 hour~ .
In the ~eco~d place t th f ibre i9 llot correctly ~pregr~ted~ ce the in~tability o~ the r@9~ lleall~3 that it~ ~egree o~ polyMerization ~crea3~ ~qith time 9 mak~g it ~mpos~ible to obta~ correct~ 3table fibre ~preg~ation co~ditio~3. ~}li9 incorreot ~pregnation giYe~ rise to th~
~ppearance of b~der mixture ~tai~ o~ the ~ibreboard ~urface, with the di~ad~tage (apart ~rom the irr~gul~r ~i~ual appearance of the board ~uri~ae~ of callsing problemR a~ the time of applyi~g fini~he~ ~uch a~ pa~t, ~ar~i~h7 plastlfied pap~r~7 etc. 7 by the di~erent degree of ab30rption i~ the ~reas showing dry re~in ~tairl3 relative to the u~tainsd areas~
In the third place, there are proble~s in the tra~sfer o~
the ~pre~ated fibre 1l 81nCe the i~correct fibre impregnation and the hi~h degree o~ tac~ o~ the re~i~ u~ed calases the formatiun of lumps o~ bonded fibre (bal~ o~ bonded ~ibre) giving rise to seriou~ problem~ in the transfer ~y3tem~
(air or mecharlical) of the impregnat;ed ~ibre to the pre~
It i~ also impo3sible to impreg~ate beîore the fibre ha~
dried, ~:Lce the re~i~ being a quie3~ ~urin,g orLe o~r dry fibre~
may be impreg~atad (that i~p aftar pas~i~g throu~h the dryer), s~nce the pa~age of the impregr~Lted fibre throug~ a dryer cau~e~ pre6ellir~g be:~ore the metarial reache~ t~e pres~S, produci~g a fibrebo~d hav~g poor mech~ical propertie~,.
To solve the a~ove problem~, the ~ve~tion provide~ a proce~ o~ the type de3cribed characteri~ed es~entially i~
that ~aid binder mixture i~ prepared from a tack :Eree urea-fcrm~ldehyde resi~ having a solid~ co~tent lyirLg bet~7~en 60~ and 70~1 pre:~erab~r 6~ and ha~ring at 25QC~ ~or a 655~
solids conten-t~ a ~risco~ity :lyirlg betweex~ 150 a:rld 300 cps and a ~re~ formaldehyde ~alue o~ les~3 than 1%9 px eferably be t~feen 0.45% and oP65,~9 to ~hieh resi~ there i~ adaed water &~ 9.
~e o~ to 55;~ v~ei~ht o~ re3i~ 0.3% to 006~ of a cataly~t cv~prissd by a~molli~n c~:Loride or ~ulphate a~d a retarder compri3ing a solution o~ ammonia or ammonia a:nd urea9 the result~g binder mixtur~ havi:~g a re~ olid~ co~te~t lyi~,~ betYveen 40~G a~d 45~ a~d a ~i8cos ty at 25QC of les~
than 15 cp~ d ~ that the grinder operate~ at a pre~sure in exee~3 of 3 bars a~d th~ ~regrlation ~tep takes place when the ~et Iiere lea~es the grinder under hi~h pre~ure and pasqe~ to the inlet of the dryer 4perating sub~t~tial1y at ~tmo~pheric pre~sure, ta1{~g advantage OI th~ expansior~ o~
the f ibrs i~ ~uch pa~a~
- In a further development, from 1 to 15% of the urea in the resin is replaced by a product having a similar chemical behaviour, preferably melamine or dicyandiamide.
The fibreboard produced by the proces~ of the invention provide~ important ~provement~ over the hither to knowr~
~ibreboard~9 particu~arly in comparison with particle board.
q~he ~o~lowing advantages may be pointed ou~:
A homo~senLou~ appear~nce of the ~urface and the in~ide 0 the boa?rd . Thi~ homogenousrle S9 even allow~ mGulding~ to be made in it.
GrQater bend~g strength~
Gre~ter re~i~tence to remosra~ o:f ~cra~ in the board.
A~ ~aid above, the re~.:Ln u~ed ~or ~he preparation of the binder fflix1;ure ha~ a :~olids corltent ly~rlg between 60% and 7C%,, preferab~y 65~o7 a~d at 25QC9 :for a 657~ solid~ content, it has a ~riscosity of 150~300 cp~
Irl certaill cas@~ there snay be a~ eco~c)mic intere~t in prepar~ng a similar re~in9 ~t with a 1 ower Yolids content (eog1 67hen the re~ to ~ u~ed at a poin~ .clo~e to ~here it i~ m~fact~Lred~ the ~ t ~crea~e in the ~arriage cost~
resultirlg from the g:reater product ~eight may be compen~ated by the reduetion of the energy required for concentrati~g the resi~)~ Such a re~in with a 60% solids content has a visco~ity at 25QC o~ 80 to 140 cps.
: I~ spite of these lo~ visco~ity values which would indicate ~br r~sins having ~imilar solid~ contents and ~ormaldehyde a~d urea co~tents) that they are resi~s with a low level of polymerizatio~ and ha~ mg high free form~ldehyde levels9 there are obtained, surprisin~ly, :Eree ~ormaldehyle v~ues of less than 1~; more precisely, lyi~g between 0.45 a~d 0~65%
(dete~mination effected ~ith the traditiona1 "cold sulphite"
method).
When impre~nat mg the fibre~ the binder mix~ure behaves a~
though it; had ~o tac~9 ~uc~ that there i8 aroided the ~Or~atiOrl 9f lump9 or !'ball~" of bonded fibr~s~ givlng rise to seriou~ problems in the tran~fer~air or mech~ical~ of the 7~
~ded Iibres9 ana there i8 avoided also the appear3nce ~ the firli~hed fibre~oard o~ irregularitie~ in the mecha~ical propertie~ d appeara~ce ~ ~rhich irregularitie~ are c~ed by the ~ri~al at the pre~s of ~ome o~ the~e lump~ or " ball~" of bonded ~ibr~ .
~ o impre~ate the ~et fibre with resin9 meterirlg mea~ are required to regulate the proportio~s of the fibre and re~in.
~e weigiht ratio ~ormally used i~:
Wei~t dry r~
- 0007 - 0v11 Weighlt dry fibre As said above9 the fibre iB ~pregnated while ~et,. In ~uch case7 the wet~ birLder mixture ~mpreg~ated ~ibre is to be dried under heat and i~ such case 9 if t;he b~der m:Lxture is not in proper condition, ~hile pa~ing t}lrough the dryer i~ beco~es partially or ~qhoLLy ge1ledy ~hich reduce~ or ancels out its bind~g po~er ~hen it i~ gelled ~n the hot plate~ pres~ to form the board, 'rhi8 problem i~ solved by preparing a binder mixture in which there ha~ been added to the resin an amount OI catalyst, rlormally a~orlium chloride or sulphate 9 lyiIlg ~ormally betweerl 0.3 ~ 0~6%~ ~hich i5 laXgeJE' than the a~o~t used :in the ca~e OI dry fibre" there i3 added al~o arl amount o~ ammoni~ 801ution (lf' the ammonia u~ed i8 i~ the norr~
commerc~ally available 25% solution) th~ amoun~ added is 0. 5 -1.5~) or an~monia a~d ureaS which act3 as retarder; likewise;
th~ a~ount of water added i~ greater tha~ i~ ~he case OI
~L.~ Y2 ~preg~ating dry ~ibre" a mi~rture being obtai~ed with a re~i~
~olids conterL~ :Lying betweeD, 40-45~0 I~ thi~ way~ th~ cture ~mpregnating the ~ibre3 doe~ not pregel o~ pas i~g through the dryer ~nd gel9 correctly during ~he hot pre~sing operatiorL in v~hich ~he ~ibreboard i~ fo2~edO
With thi~ b~nder mixtl;Lre a~ailable7 the impreg~atiorl may be e~fec l;ed taki~g ad~antage o~ the ç'xpan8io~ caused ~hen the ~ibre l e~re~ th~ grixlderg ~ich ~nerally operates st a high pres~ure (over 3 bars~ 9 ~d passes to the dryer i~let ~hich operates practieally at ~o~l pre~sure. The mea~ured amount OI re~ may be aclded here ~ithout the need OI a~y ~tirr~g me chanis~ 1.
The impreg~atio~ obtained i~ genera:L9 high quality.
~hi~ may be observed, among other ~ays, because ~ere are no stains formed by drops of poorly im~ibed mixture ill the fibre on ~he board surface~.
The binder mixture was prepared with a urea-fo~aldehyde res~ having a solid~ content of 65~" a ~iscosity at 25QC of 225 ops a~d a free formaldehyde ~alue o~ 0.50%, i~ a mixing vessel equipped YYith stirr~ng mea~s9 i~ the ~a~r and proport ions given below.
10V part3 in ~ei~L~ of the above re~in ~ere poured into the preparat:ion vessel~ Thereafter 40 parts in weI~ht of water ~d 4 p~t~ 7eight o:e a cataly~t ~ere addedO The cataly~t prepared as follo~s:
~ o 100 p~ts o~ ~?ater there ~ere added 27 parts OI 25%
a~o~ia acting a~ retarder arLd 13 partB of a~o~ium chloride The previou~ly ~tirred re~i~ and catalyst binder mi~ture has a gellirlg time at lOOQC of 3 minute3 and a very good ~tability o~ the sh~lf~ llhe ~risco~ity og the thus prepared mixture i3 15 Gp~ re~ olid~ c~tent is 45%~
The f:~bre used wa~ a mixture of pi~- and poplar ~YOOd chip~3, at a rate of 90~ a~a 10% respectivel~y~
r~he fibre wa~ pretrea-ted with a para~f~n emul~io~ rrhe amount of paraffin ~upplied o~er the dry fibre wa~ 1% paraff~
solids ., The amount o~ biIlder corre~pondirLg to 1 1 7 320 g of ~et ~ibre having a 50% moisture level is 1"107 g, gi~iIlg 129427 g o~
bonded f ibre .
r~he ~qeight of the bonded ~ibre o~ce it has been dried to the correct moisture level :Eor the ma~u:fac ture of fibre board i3 7,000 g, The thus obtaiIled material contai~ 5,660 g of dry ~ib;re" 498 g of res~ solid~ a~d 840 g o~ water.
R~P~ 3 Manu~actur~ of f ibreboard u~h ~ ne fibr~ ~preg~ated according to th~ pr~iou~ example ~ fibre dri~d ~ter i~n~reg~tion) ~ras u~ed for the ma~ufa~ture of fibreboard v~ith the fo~owing proce~
~ rhe ~re~ated Iibra lHa~ ~oulded irl a 500 x 500 mm laborator~ former. It ~as prepre~Jed cold in a 500 ~ 500 m~
SIEMPEI~AMP laboratory pres~ ~or 60 ~ec at a pres~ure of 15 }~g/cm2, ~he edge~ of the block were trimmed to 450 x 450 mm prior to hot pr~ing, The 7~000 g of impre~ated fibre were suîficien~ to prepare a finished board n3easuri~g 450 x 450 mm by 17 mm thick, with a den~ity of 720 kg/m3~
The pressing o~ th~ cold prepressed ~ibre blocks was effected ~n a SIEmP:EL~AMP laboratory pressy having both platen~ electrically heated to a temperature of 180QC7 under a pre~ure of 23 kg/cr~2, Yrith aJuto~atic ventilatio~ de~ice.
The pre s s ing t ime was 6 minut e 3, A:~ter sallding the board~" the re~ult~ ~ere as follow~:
SPECIFI CA~IONS OF THE~ BOARD
~hlC~ 6 ~ 0 5 De~ity k~ 3 715 Behdi~g strerlgth k~/c~n~ 339 ~ensile ~tr~ngth kg/c~2 9D6 Absorptio~ ~ ~ater at 20QC % ~1.5 Swell~:llg i~ water ~t ~OQC % 3~,8 Re~i~terlce to ~cre~
removal orl surface l~g 160 Re~i~tence to sGrew removal ~ ed~e kg 120 The above te8 t3 wer~ effeeted with fibreboard~
ma~ufac tured Yrith den ities ~et to ~ partlcu~ alue . They may also be marlufact~Lred ~7ith densities other than tho~e cho~en, there varying m thi~ ca~e ~ain:Ly the ten~ile strength ~alue~ a~d the be:nding 3trength values to a le~ser extent., Th~e propertie~3 go dow~ at loqver densities and i~crea~e at higher de~sities.
In the ~ir~t place, there i~ a hi,~h degree of in~tabilityp ~i~ce th~ resin rem~i~ ~ table f`or a period of le~ th~ 48 hour~ .
In the ~eco~d place t th f ibre i9 llot correctly ~pregr~ted~ ce the in~tability o~ the r@9~ lleall~3 that it~ ~egree o~ polyMerization ~crea3~ ~qith time 9 mak~g it ~mpos~ible to obta~ correct~ 3table fibre ~preg~ation co~ditio~3. ~}li9 incorreot ~pregnation giYe~ rise to th~
~ppearance of b~der mixture ~tai~ o~ the ~ibreboard ~urface, with the di~ad~tage (apart ~rom the irr~gul~r ~i~ual appearance of the board ~uri~ae~ of callsing problemR a~ the time of applyi~g fini~he~ ~uch a~ pa~t, ~ar~i~h7 plastlfied pap~r~7 etc. 7 by the di~erent degree of ab30rption i~ the ~reas showing dry re~in ~tairl3 relative to the u~tainsd areas~
In the third place, there are proble~s in the tra~sfer o~
the ~pre~ated fibre 1l 81nCe the i~correct fibre impregnation and the hi~h degree o~ tac~ o~ the re~i~ u~ed calases the formatiun of lumps o~ bonded fibre (bal~ o~ bonded ~ibre) giving rise to seriou~ problem~ in the transfer ~y3tem~
(air or mecharlical) of the impregnat;ed ~ibre to the pre~
It i~ also impo3sible to impreg~ate beîore the fibre ha~
dried, ~:Lce the re~i~ being a quie3~ ~urin,g orLe o~r dry fibre~
may be impreg~atad (that i~p aftar pas~i~g throu~h the dryer), s~nce the pa~age of the impregr~Lted fibre throug~ a dryer cau~e~ pre6ellir~g be:~ore the metarial reache~ t~e pres~S, produci~g a fibrebo~d hav~g poor mech~ical propertie~,.
To solve the a~ove problem~, the ~ve~tion provide~ a proce~ o~ the type de3cribed characteri~ed es~entially i~
that ~aid binder mixture i~ prepared from a tack :Eree urea-fcrm~ldehyde resi~ having a solid~ co~tent lyirLg bet~7~en 60~ and 70~1 pre:~erab~r 6~ and ha~ring at 25QC~ ~or a 655~
solids conten-t~ a ~risco~ity :lyirlg betweex~ 150 a:rld 300 cps and a ~re~ formaldehyde ~alue o~ les~3 than 1%9 px eferably be t~feen 0.45% and oP65,~9 to ~hieh resi~ there i~ adaed water &~ 9.
~e o~ to 55;~ v~ei~ht o~ re3i~ 0.3% to 006~ of a cataly~t cv~prissd by a~molli~n c~:Loride or ~ulphate a~d a retarder compri3ing a solution o~ ammonia or ammonia a:nd urea9 the result~g binder mixtur~ havi:~g a re~ olid~ co~te~t lyi~,~ betYveen 40~G a~d 45~ a~d a ~i8cos ty at 25QC of les~
than 15 cp~ d ~ that the grinder operate~ at a pre~sure in exee~3 of 3 bars a~d th~ ~regrlation ~tep takes place when the ~et Iiere lea~es the grinder under hi~h pre~ure and pasqe~ to the inlet of the dryer 4perating sub~t~tial1y at ~tmo~pheric pre~sure, ta1{~g advantage OI th~ expansior~ o~
the f ibrs i~ ~uch pa~a~
- In a further development, from 1 to 15% of the urea in the resin is replaced by a product having a similar chemical behaviour, preferably melamine or dicyandiamide.
The fibreboard produced by the proces~ of the invention provide~ important ~provement~ over the hither to knowr~
~ibreboard~9 particu~arly in comparison with particle board.
q~he ~o~lowing advantages may be pointed ou~:
A homo~senLou~ appear~nce of the ~urface and the in~ide 0 the boa?rd . Thi~ homogenousrle S9 even allow~ mGulding~ to be made in it.
GrQater bend~g strength~
Gre~ter re~i~tence to remosra~ o:f ~cra~ in the board.
A~ ~aid above, the re~.:Ln u~ed ~or ~he preparation of the binder fflix1;ure ha~ a :~olids corltent ly~rlg between 60% and 7C%,, preferab~y 65~o7 a~d at 25QC9 :for a 657~ solid~ content, it has a ~riscosity of 150~300 cp~
Irl certaill cas@~ there snay be a~ eco~c)mic intere~t in prepar~ng a similar re~in9 ~t with a 1 ower Yolids content (eog1 67hen the re~ to ~ u~ed at a poin~ .clo~e to ~here it i~ m~fact~Lred~ the ~ t ~crea~e in the ~arriage cost~
resultirlg from the g:reater product ~eight may be compen~ated by the reduetion of the energy required for concentrati~g the resi~)~ Such a re~in with a 60% solids content has a visco~ity at 25QC o~ 80 to 140 cps.
: I~ spite of these lo~ visco~ity values which would indicate ~br r~sins having ~imilar solid~ contents and ~ormaldehyde a~d urea co~tents) that they are resi~s with a low level of polymerizatio~ and ha~ mg high free form~ldehyde levels9 there are obtained, surprisin~ly, :Eree ~ormaldehyle v~ues of less than 1~; more precisely, lyi~g between 0.45 a~d 0~65%
(dete~mination effected ~ith the traditiona1 "cold sulphite"
method).
When impre~nat mg the fibre~ the binder mix~ure behaves a~
though it; had ~o tac~9 ~uc~ that there i8 aroided the ~Or~atiOrl 9f lump9 or !'ball~" of bonded fibr~s~ givlng rise to seriou~ problems in the tran~fer~air or mech~ical~ of the 7~
~ded Iibres9 ana there i8 avoided also the appear3nce ~ the firli~hed fibre~oard o~ irregularitie~ in the mecha~ical propertie~ d appeara~ce ~ ~rhich irregularitie~ are c~ed by the ~ri~al at the pre~s of ~ome o~ the~e lump~ or " ball~" of bonded ~ibr~ .
~ o impre~ate the ~et fibre with resin9 meterirlg mea~ are required to regulate the proportio~s of the fibre and re~in.
~e weigiht ratio ~ormally used i~:
Wei~t dry r~
- 0007 - 0v11 Weighlt dry fibre As said above9 the fibre iB ~pregnated while ~et,. In ~uch case7 the wet~ birLder mixture ~mpreg~ated ~ibre is to be dried under heat and i~ such case 9 if t;he b~der m:Lxture is not in proper condition, ~hile pa~ing t}lrough the dryer i~ beco~es partially or ~qhoLLy ge1ledy ~hich reduce~ or ancels out its bind~g po~er ~hen it i~ gelled ~n the hot plate~ pres~ to form the board, 'rhi8 problem i~ solved by preparing a binder mixture in which there ha~ been added to the resin an amount OI catalyst, rlormally a~orlium chloride or sulphate 9 lyiIlg ~ormally betweerl 0.3 ~ 0~6%~ ~hich i5 laXgeJE' than the a~o~t used :in the ca~e OI dry fibre" there i3 added al~o arl amount o~ ammoni~ 801ution (lf' the ammonia u~ed i8 i~ the norr~
commerc~ally available 25% solution) th~ amoun~ added is 0. 5 -1.5~) or an~monia a~d ureaS which act3 as retarder; likewise;
th~ a~ount of water added i~ greater tha~ i~ ~he case OI
~L.~ Y2 ~preg~ating dry ~ibre" a mi~rture being obtai~ed with a re~i~
~olids conterL~ :Lying betweeD, 40-45~0 I~ thi~ way~ th~ cture ~mpregnating the ~ibre3 doe~ not pregel o~ pas i~g through the dryer ~nd gel9 correctly during ~he hot pre~sing operatiorL in v~hich ~he ~ibreboard i~ fo2~edO
With thi~ b~nder mixtl;Lre a~ailable7 the impreg~atiorl may be e~fec l;ed taki~g ad~antage o~ the ç'xpan8io~ caused ~hen the ~ibre l e~re~ th~ grixlderg ~ich ~nerally operates st a high pres~ure (over 3 bars~ 9 ~d passes to the dryer i~let ~hich operates practieally at ~o~l pre~sure. The mea~ured amount OI re~ may be aclded here ~ithout the need OI a~y ~tirr~g me chanis~ 1.
The impreg~atio~ obtained i~ genera:L9 high quality.
~hi~ may be observed, among other ~ays, because ~ere are no stains formed by drops of poorly im~ibed mixture ill the fibre on ~he board surface~.
The binder mixture was prepared with a urea-fo~aldehyde res~ having a solid~ content of 65~" a ~iscosity at 25QC of 225 ops a~d a free formaldehyde ~alue o~ 0.50%, i~ a mixing vessel equipped YYith stirr~ng mea~s9 i~ the ~a~r and proport ions given below.
10V part3 in ~ei~L~ of the above re~in ~ere poured into the preparat:ion vessel~ Thereafter 40 parts in weI~ht of water ~d 4 p~t~ 7eight o:e a cataly~t ~ere addedO The cataly~t prepared as follo~s:
~ o 100 p~ts o~ ~?ater there ~ere added 27 parts OI 25%
a~o~ia acting a~ retarder arLd 13 partB of a~o~ium chloride The previou~ly ~tirred re~i~ and catalyst binder mi~ture has a gellirlg time at lOOQC of 3 minute3 and a very good ~tability o~ the sh~lf~ llhe ~risco~ity og the thus prepared mixture i3 15 Gp~ re~ olid~ c~tent is 45%~
The f:~bre used wa~ a mixture of pi~- and poplar ~YOOd chip~3, at a rate of 90~ a~a 10% respectivel~y~
r~he fibre wa~ pretrea-ted with a para~f~n emul~io~ rrhe amount of paraffin ~upplied o~er the dry fibre wa~ 1% paraff~
solids ., The amount o~ biIlder corre~pondirLg to 1 1 7 320 g of ~et ~ibre having a 50% moisture level is 1"107 g, gi~iIlg 129427 g o~
bonded f ibre .
r~he ~qeight of the bonded ~ibre o~ce it has been dried to the correct moisture level :Eor the ma~u:fac ture of fibre board i3 7,000 g, The thus obtaiIled material contai~ 5,660 g of dry ~ib;re" 498 g of res~ solid~ a~d 840 g o~ water.
R~P~ 3 Manu~actur~ of f ibreboard u~h ~ ne fibr~ ~preg~ated according to th~ pr~iou~ example ~ fibre dri~d ~ter i~n~reg~tion) ~ras u~ed for the ma~ufa~ture of fibreboard v~ith the fo~owing proce~
~ rhe ~re~ated Iibra lHa~ ~oulded irl a 500 x 500 mm laborator~ former. It ~as prepre~Jed cold in a 500 ~ 500 m~
SIEMPEI~AMP laboratory pres~ ~or 60 ~ec at a pres~ure of 15 }~g/cm2, ~he edge~ of the block were trimmed to 450 x 450 mm prior to hot pr~ing, The 7~000 g of impre~ated fibre were suîficien~ to prepare a finished board n3easuri~g 450 x 450 mm by 17 mm thick, with a den~ity of 720 kg/m3~
The pressing o~ th~ cold prepressed ~ibre blocks was effected ~n a SIEmP:EL~AMP laboratory pressy having both platen~ electrically heated to a temperature of 180QC7 under a pre~ure of 23 kg/cr~2, Yrith aJuto~atic ventilatio~ de~ice.
The pre s s ing t ime was 6 minut e 3, A:~ter sallding the board~" the re~ult~ ~ere as follow~:
SPECIFI CA~IONS OF THE~ BOARD
~hlC~ 6 ~ 0 5 De~ity k~ 3 715 Behdi~g strerlgth k~/c~n~ 339 ~ensile ~tr~ngth kg/c~2 9D6 Absorptio~ ~ ~ater at 20QC % ~1.5 Swell~:llg i~ water ~t ~OQC % 3~,8 Re~i~terlce to ~cre~
removal orl surface l~g 160 Re~i~tence to sGrew removal ~ ed~e kg 120 The above te8 t3 wer~ effeeted with fibreboard~
ma~ufac tured Yrith den ities ~et to ~ partlcu~ alue . They may also be marlufact~Lred ~7ith densities other than tho~e cho~en, there varying m thi~ ca~e ~ain:Ly the ten~ile strength ~alue~ a~d the be:nding 3trength values to a le~ser extent., Th~e propertie~3 go dow~ at loqver densities and i~crea~e at higher de~sities.
Claims (7)
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the manufacture of lignocellulosic material fibreboard, comprising the steps of preparing a binder mixture, providing a lignocellulosic material, shredding said material, digesting said shredded material, grinding the resulting product, impregnating the fibre with said binder mixture, drying the fibre and pressing it, wherein said binder mixture is prepared from a tack free urea-formaldehyde resin having a solids content lying between 60% and 70% and having at 25°C, for a solids content of 65%, a viscosity lying between 150 and 300 cps and a free formaldehyde value of less than 1%, to which resin there is added water in an amount of 40 to 55 weight % of resin, from 0.3% to 0.6% of a catalyst comprised by ammonium chloride or sulphate and a retarder comprising a solution of ammonia or ammonia and urea, the resulting binder mixture having a resin solids content lying between 40% and 45%
and a viscosity at 25°C of less than 15 cps; the grinder operates at a pressure in excess of 3 bars and the impregnation step takes place when the wet fibre leaves the grinder under high pressure and passes to the inlet of the dryer operating substantially at atmospheric pressure, taking advantage of the expansion of the fibre in such passage.
and a viscosity at 25°C of less than 15 cps; the grinder operates at a pressure in excess of 3 bars and the impregnation step takes place when the wet fibre leaves the grinder under high pressure and passes to the inlet of the dryer operating substantially at atmospheric pressure, taking advantage of the expansion of the fibre in such passage.
2. A process as claimed in claim 1 in which the resin has a solid content of 65%.
3. A process as claimed in claim 1 in which the resin has a free formaldehyde value between 0.45 and 0.65%.
4. The process of claim 1, claim 2 or claim 3, wherein the pressing step comprises a cold prepressing of the fibre and a hot pressing in a platen press.
5. The process of claim 1, claim 2 or claim 3, wherein prior to impregnation, the material is treated with a paraffin emulsion providing an amount of paraffin solids of about 1%
by weight of the dry fibre.
by weight of the dry fibre.
6. The process of claim 1, claim 2 or claim 3, wherein the weight ratio of dry resin to dry fibre lies between 0.07 and 0.11.
7. The process of claim 1, claim 2, or claim 3, wherein in the resin part of the urea, lying between 1 and 15%, has been replaced by melamine and dicyandiamide.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| ES494,323 | 1980-08-18 | ||
| ES494323A ES494323A0 (en) | 1980-08-18 | 1980-08-18 | PROCEDURE FOR MANUFACTURING LIGNOCELLULOSIC MATERIAL FIBER BOARDS |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1190372A true CA1190372A (en) | 1985-07-16 |
Family
ID=8480972
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000382883A Expired CA1190372A (en) | 1980-08-18 | 1981-07-30 | Process for the manufacture of lignocellulosic material fibreboard |
Country Status (8)
| Country | Link |
|---|---|
| AR (1) | AR225361A1 (en) |
| AT (1) | AT374517B (en) |
| CA (1) | CA1190372A (en) |
| DE (1) | DE3132468A1 (en) |
| ES (1) | ES494323A0 (en) |
| MX (1) | MX158012A (en) |
| NO (1) | NO156290C (en) |
| SE (1) | SE442101B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1754012A1 (en) * | 2004-05-24 | 2007-02-21 | Basf Aktiengesellschaft | Molded elements made of - materials containing lignocellulose |
| WO2006010192A1 (en) * | 2004-07-27 | 2006-02-02 | Orica Australia Pty. Ltd. | System for providing powder coated reconstituted cellulosic substrate |
| US20080292886A1 (en) * | 2007-03-23 | 2008-11-27 | Hercules Inc. | Adhesive formulations containing urea additives, methods of forming plywood therewith, and plywood products made thereby |
-
1980
- 1980-08-18 ES ES494323A patent/ES494323A0/en active Granted
-
1981
- 1981-06-01 MX MX187642A patent/MX158012A/en unknown
- 1981-07-27 AT AT0330181A patent/AT374517B/en not_active IP Right Cessation
- 1981-07-30 CA CA000382883A patent/CA1190372A/en not_active Expired
- 1981-08-06 AR AR286358A patent/AR225361A1/en active
- 1981-08-07 SE SE8104755A patent/SE442101B/en unknown
- 1981-08-14 NO NO812760A patent/NO156290C/en unknown
- 1981-08-17 DE DE19813132468 patent/DE3132468A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| DE3132468A1 (en) | 1982-05-06 |
| NO156290B (en) | 1987-05-18 |
| NO156290C (en) | 1987-08-26 |
| ES8104064A1 (en) | 1981-04-01 |
| AR225361A1 (en) | 1982-03-15 |
| SE442101B (en) | 1985-12-02 |
| SE8104755L (en) | 1982-02-19 |
| ES494323A0 (en) | 1981-04-01 |
| ATA330181A (en) | 1983-09-15 |
| NO812760L (en) | 1982-02-19 |
| MX158012A (en) | 1988-12-29 |
| AT374517B (en) | 1984-05-10 |
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