CA1278961C - Process and apparatus for applying bonding agent and a process for forming reconsolidated wood product - Google Patents

Abstract

ABSTRACT
A PROCESS AND APPARATUS FOR APPLYING BONDING AGENT
AND A PROCESS FOR FORMING RECONSOLIDATED
WOOD PRODUCT
Process and apparatus for introducing bonding agent in an improved manner to flexible open lattice work web of naturally interconnected wood strands, a substantial proportion of which are substantially discrete but incompletely separated from each other. The web with bonding agent applied may be compressed above or with others to form a reconsolidated wood product. The application of bonding agent is performed using at least one applying roller pair (102, 104) in which one or more rollers is corrugated to thereby allow better infiltration of the agent. Squeeze rollers (118) advantageously remove excess bonding agent. The applying rollers are preferably disposed in a bath (126) and the bonding agent, for example a foam, may be applied in the bath to be carried upstream by the rotation of the applying rollers. Conveniently a shroud (148) is provided beneath the applying rollers to guide bonding agent upstream.

Description

l)HVlt~ uLLl~uN l~ltL~I. Sl.~ 4 4Ylab ~ 14 ~_~d~ 8~361 A PROCESS AND APPARATUS ~OR APPLYING ~ONDING ~E~T
AND A PROC~SS FOR FORMING RECONSOLI~A~ED
WOOD PRO~UCT

~hi~ invention rela~es to 8 proCess and apparatus for appl~ng bonding agent and to a pro~ess for ~orming a reconsolidated wood product as well as to a recon~olidate~ wood produc~ ~ormed ~y ~he latter 5 ~rocess.
Australian Patent ~p~ ication 510,845 describes a reconsolidated wood product eorm~d from at l~ast one ~lexible open lattice work web of naturally interconnected wood strands generall~
10 ali~ned along a ~ommon grain direc~io~, a su~stantial proportion of the strands ~eing ~bst~ntially c di~cret~ t incompletely separatQd from each other,and the web having been conso~idat~d by co~pres~ion wh~lst ~ubstantially main~a~ning the wood 15 strand~ aI~gned along the ~ommon ~r~ln direction and . . . ~

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the strand~ being bonded together to hold them in juxtapo~itionæ a~umea p~r~uant to the consolidation.
That p~ten~ sp~cific~t on al~o de~cribes a pro~e~ ~or form~ng a recon~olidatea woOa proauct from a fl~lbl~ opsn latt~ce work web of natur~lly ~n~e~conn~cted woo~ ~trands, ~h~ we~ being forme~ by p~rtiall~ rending n~tur~l wood ~o that the s~rana~
are qeneral~ aliqned along a common grain ~irection, a substantia~ proportion of the strana~ being ~ubstantially ~i~crete but incompletely sep~ra~ed f~om ~ach other, ~nd the proceYs ~ompri~ing comp~ssinq the w~b to consolidate the st~an~ whilst m3int~ining them 5uch a~ to ~ubstanti~ly e~tend in the ori~in~l grain direction and bond~nq the strands to~ether to ho~d them in ju~tapositions as~umed pursuant ~o the consolidation.
One~f the dif~iculties associated with the proces~ of Austr~lian P~tent ~pecifica~ion 510,84$ i5 sati~factorily introducin~ the bondinq agent to the web of naturally in~erconnected wood strands. That p~tent speciÇication proposed introducing 3 oamed ~onding aqent to the compre~ion mould or spraying or otherw~e applying the bondinq agent during or aft~r the ~ormation of the web, but a p~rticularly pre~rred proposal was to dip the web into a ba~h of l~qu~d re~in.
It has ~een ~ound to ~e p~rticularly i~portant in the formation of a reconsolidated wooa produc~ o~ th~ type disclo~d in Au~tralian Pat~nt 30 ~pe~ific~tion 51~,845 to en~ure that the bonding ~gent is thoroughly disper~ed through the web.
Accordinq to the present inYention there i8 proYide~ a pro~e~ f~r spplyln~ ~onding agent to a fle~ible open lattice work whb of naturallY

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7~3g61 interconn~cte~ wooa ~trand~ prior to compressing and con~olidating ~aid web ~o form a recon~ollds~e~ wood product, said wub bein~ forme4 hy partially ren~ing n~tura~ wood ~o ~h~t ~aid str~nds a~e genera~ly align~d along ~ common g~8in ~irection with a subst~nti~l proport~on of ~a~d ætrands b~in~
sub~tanti~lly ~i~crete but inaompl~t~ly 8~parated from ~ach other, said pro~e5s compri~ing pa8Bing the we~ through a p~r o spplying rollcr~ of wh~ch at lea~t one roller is aorru~ate~ whereby a por~ion o~
the web pas~in~ through the applying ro~le~ at any on~ tim~ pr~d ls~erally without substantial further ~p~at~on of the ~rands, app}yin~ bonding agent to ~3i~ portion of the web immadiately prior to its pa8sage through the pair o applying roller~ or while the portion i~ spread by the pair o~ appl~ing roller~ and re~oving e~ces~ bonding agent from the web ~ownstre~m o~ ~aia appl~ing roller pair, for e~ample by means of a pair o~ squeeze roller~.
Further accordin~ to the present invention there i8 ~rnvided apparatus ~or applying bon~ing : aqent to a fl~ible open lattic~ wo~k web o na~ur~lly interconn~cted wood ~trands formed by partially rend~ng natural wood ~o that said strand~ ~
are gener~lly ali~ned 810ng a common grain direction with a ~u~st~ntial proport~on o~ ~aid strand~ being ~ub~t~ntially d~rete but Incomplet~ly separatea rom each other, ~aid apparatus compri~ing a pair o~
applyin~ rolle~ adapted to recei~ the web therethrough, at least one of the roller~ of said pair having a corrugat~d outer ~urfaae whereby to de~ine an e~ten~ed path ~or ~he web acro~s the width thereo~ and to thereby open th~ web, mean~ fo~
~pplying bonding ~gent to ~ por~ion of the we~

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imme~ist~ly upstre~m o~ ~he 3pplying roller p~ir or to the open0d po~tion of the web, and a pai~ o sque~ze ro~ler~ for removinq ~c~s~ bon~in~ agent f~m the web.
By the ~re~ent invention, we have found that the lattice o the we~ ~s res~liently opensd up a~
the w~ pa~es ~hrough the applying roller pair ~ue to the ~ncr~dssd lat~r~1 p3~h A~f~ned ~y the or ea~h eorruqa'ce~ roll~r, th~t i~ th~ tncrea~ed sur^face len~th of the roller in the axial d~rection thQreof.
The bond~n~ agen~ may accorBingl~ more readily enter the body sf the ~b on~ coBt the etrsn~. It 1~ not nece~sary Por the ~e~ to be ~ubstantially compressed between th~ nip ~ the applying rollars, ~erely that its efective ~urace area be increa~e~ by ~ollowing the con~ou~ of th~ or each corrugat~d roller.
It ~ preferred that hoth roller~ of the applying roller pa~r are aorrugated in wh~ch c~e the peaks of th~ respecti~e rolle~s ~houl~ be of~et, and may int~rme~h, to de~ine a sinuou~ path between the applyin~ roller~ which i~ of greater len~th than the - a~ial length of the rolle~. As noted previously the nip between the rollers nee~ not be ~ubstantially smaller than the dep~h of the we~ sin~e it is impo~tant not to furthsr b~eak up the web by additional ~eparation of the strands. The corrugations may take any de~ir~d ~hape ~d ara conveniently sub~tsntially si~u30id~1 or sinusoidal but with lanas between ~he peak~ (i.e. ~he valleys are extended)~
Ths applying rollers may take any suitable ~orm ~nd be ma~e of, for e~ampl~, me~al, rubb~r or plastics, Ca~t iron, ~tainle~s teel and alumi~ium are p~eferred metal roller m~terial~. Alte~na~ively, CC ~ I~ ' 1C LJnV 1~ ~ UL~ I ~Ul`I I ICLD . C~ ) O~C~

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the or ea~h applying roller ma~ be pn~umstic, and it i preferr~d tha~, where only one of the roll~r~ in the roller p~ir i~ corru~ated, at lea~t ~he other ~5 pneumatic .
A ~e~ond pair o applying roller~
inaorporatiA~ ally one or more of the aforem~nt~oned features m~y be provl~d up~tream or down~tr6~am of th~ first m~ntioned pair to ~acilitate in~iltration o~ the bon~ing a~e~t to the l~tti~e work. Th~
~pa~ing b~'cween 'chf3 ~wo pa~rs of spplyin~ roll~r~ may be min~mal, for esample in the r~nge o 25~100 nun or le83, pr~erably towar~s ~he lo~er end o~ the r~ e.
A sUPport rolle~ or other ~upport me~n~ may b~
provided b~twe~n th~ two pairs of applyin~ rollers, The n~p between the roller~ o~ the two pair~ of ~pplyin~ rolle~s may be ~ub~tantial~y the sam~, bu~
mo~t ~dvantageou~ly the nip betwe~n th~ downstr~am pal~ o~ ~pplyi~g roller~ is slightly ~malle~ than that bet~een tho up~r~am pair. In a pre~rred embodim~t whe~ our applyinq roller~ ar~
corrug~te~ the ~piceg o the peaks of the up~tream pair o applylng rollers l~e in a common plane in the nip, wh~le ~he apices of the pea~æ of ~he down~tr~
paix of ~pply~ng roller~ intermesh in the nip.
~he or each pa~r of applying rollers may ~e d~iven or non~driven, or one of the two pairs may be drivQn. If nona of the appl~ing roller~ iB ~riYen it will be ne~essary to provide other mean~ for displacing the web therethrough. ~dvanta~eou~ly, p~ir of cyl~ndri~l driv~ roller~ i8 provided upstre~m of the one pair or both pairs o~ applyin~
roll~r~ whether or not th~ appl~ing rollers ar~
driv~n, and ~upport ~an~ or example in the form o~
a single roller m~y b~ provided to guide the w~b from JtlVIG~ 0~ ~_U--LI~JIY l'l~LC. Dl.~ b~ 4~WC 1~

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the ~ri~e roller~ into the nip o~ the on~ pair or upstre~m p~ir o~ applyin~ roller~.
The m~an~ ~or remo~ing e~cQ~ bon~in~ age~t from the web may take any suitable form, but ~æ
S indi~ated here$nbefore p~e~ly compr~e~ a p~ir of ~quee~e rol1er~ whch are conveniently fo~med o~
rubber or ar~ pneumatic. Such squee~e roller~ are pr~ferabl~ plain ro~le~ and may be mounted in floating msnner. ~he combination of at least on~
corrugated applying roller an~ the s~ue~e roll~r3 is a~apted to 3uccessi~ely compres~ and relas the web prima~ily o~ sub~tantially in the direction o ~he depth t~er~of and to permanently ~na~ea~e the width of the w~b without bre~kin~ th2 lattice-continuity.
I~ ha~ be~n found that deorming the web by me~ns o~
the ~ le~t one corruqatsd applying roller such ~
to increase the width o the wsb in the rang~ 1~ to 35~, preferab~ about 25~ i~ æsti~factory ~or webs ! f~rme4 rom young pinu~ radiata trHe~.
A ~upport roll~r or other carrier mean~ may be pro~i~ed ~etween the one applying roller pair or ~he downstrea~ applying rolle~ pair and the mean~ ~or - r~moving exce~ bo~ding aqent. Such carrier means and the aforementione~ other optional ~UpPort mean~
a~e all intend~d to prev~n~ ~mall ~eparated strands or splint~rs ~rom ~eparating from the w~b, but where they ar~ in the form of roll~rs, and particul~rl~ ~f the bon~ing 3qent is 3pplied as a ~oam, they may al~o ~erve the ~unction o~ a~sisting to return e~ce s bonding a~ent to a position up~ream of the one pair or ~h~ up~tream pair of applyi~g rolle~s for re-u~e.
A shroud ~t lea~t ben~ath the one pair o~ e~ch pair of applying roller~ may be provided to a~ t ~h~
retu~n c~ the e~ces~ ~onding age~t to a po~tion __ VI~V l e ~ ULL I ~UI`I IYI~L~ 4 4Yla~

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upstre~m of ~h~ applying ~ollers, a}thou~h e~cc~s~
bon~ing age}lt ma~ also be carried back o~rer the top o the ~pplying rollers ~y the rotating a~tion thereo~ .
~he bondinq agent ma~ be of any ~uit~le Sype, that c~n be readily infiltrate~ in~o the w~b.
For e~:ample a resin agent ~uch as ta~nin may be disso~ved in w~t~r and applied as ~ liquid either by imm~rsion, or br f lo~ through ~ cur~in, or sprayed wi'ch ~ir un~er pre~ure, or the liquid may be PoAmed with ~ir or ~ther ~as and the oam ~n~iltrat~d into the ~arim ~eb. The bond~ng agent ma~ be metered o~to the we4 on either or both ma~or sura~ up~traam o the or each corxu~ated roller pair where it is lS carried orw~rd into the nip of the rollerg ~nd worked into the ~erim web. Alternat~vel5~ th~ ~onding agent may b~ applied to t:he applying roller¢ ana be carried by them into contact with the scrim w~b.
~ Alt~rnati~ely again, the bonding agent may be applie~
~o to u bsth between ~he one pair or tbe dow~tream pair of appl~in~ roll~r~ and the mean~ for remo~in~ e~c~
~ bonding ~ent, and he carried up~tre~m ~r th~
~tating ~ctio~ of the applying roll~r~.
hhen the bonding agent solution ~or emul8~0n) i~ a~plie~ as a foam, the ~oam ma~ h~vs a density o the or~er o~ lO0 g~litre, However, ~he proces~ ha~ ~e~n operat~d ~ati~fac~orily with a foam dansity in ~he range 30 ~1 to l~0 g/l and h~avier den~tie~ may b~ con~idered ~or ~pecific applioations, Foam den~ity controls the pick up of resi~ and moi~ture if it is a solution. It i8 al~o anticipate~ tha~ oam~d liquid ~sin~ ma~ be u~sd neat.
Compression 2n~ consolidation of th~ web, 39~;1 for ~xample by curing the bond~ng agent while the w~b is compres~e~ on a non-, ~emi- or fully- continuous basi~, occurs ~ownstream o the ~pplication of 40nding ~ent, Two or more ~f th~ we4~ may ~e ~uperpo~ed prior to compre~sion and consolidatio~.
~ urther acc~rding to the pr~sen~ inv~n~ion therQ i8 provided a proces6 ~or ~orming ~
recon~olidated woo~ produ~t from a plurality of sup~rpo~ed ~le~ible open latt~ce work webs of naturall~ inter~onne~te~ wood strands, each o~ said webs being ~o~mod by ptrti~lly ronding natural wood ~o that ~id ~trands ~he~eo are generally ali~ned along a common grain di~ection, a sub~tantial proportion oF said ~trands of ea~h we~ bein~
sub~tantially ~iscrete but ineompletely separste~
~rom ~ach other, said proCess ~ompri~in~ applying bonding agent to ~ai~ webx, ~uPërPosing th~ webs, compre~sinq the ~uperpos~d webs to con~olidate th~
stran~s and curlng the bonding agent to bond the 20 8tr~nds and ~ebs together, ~aid applic~tion of bon~ing a~ent compriEing pa~sing each wob ~hrough a pair of ~pplying rollers of which at least one roller is aorrugated whereb~ a portion o the web pa~sing throu~h the roll~r~ at any on~ time i~ 8p~ead 25 later~l~y without ~ub~tantial furthe~ sepa~ation of 'che strandg, applying bonding apent to ~aid portion o~ the we~ ~mlnedia~el5~ prior to its paæsage through the pair o~ applying roller~ or while the portion spread ~ th~ pa~r of ~pplyinq roller~ and removin~
30 e~ccess bonding agent from the web down~t~e~m of ~aid ro 1 ler pai r .
Still furth~r ac~ording to the present ~nv~ntion there i8 proviae~ a reconsolidated wood product orn~e~ by the proce~ ~escribed in the 1Y:5 ~ 14 IJHVlt~ ULLl~iUN MtL~. 61~ 654 4906 P. 12 96~

i~me~iate1y preceding paragr~ph.
rwO embo~m~nts o~ apparatus ~nd a proces~
in a~cord~nce with the invention will now be deRcrib~d by way of e~ampl~ only w~h reference to the accompanying ~rsw~ngs in which:
FIGV~E 1 ig a disqram æhow~ng the steps in procsssing re~on~oliaate~ wood products ~n ao~ordance with the invantion de~Gri~ed in ~he aforementioned Au~rali~n pat~nt sp~c~~cation 510,845;
FI~URE 2 ~ ~ s~hema~ic diayram o~ one embo~im&~t o~ app~ratus u~ed in practl~ln~ the pro~es~ of the pre~ent invention;
FIaURE 3 i8 a ~ectional sids Yiew of a second em~o~ime~t o apparatus u~ed in practi~ing th~
proce~ of the present invention; and FIGU~E 4 ~ a ~ragmentary side Yi~W of an ~pplying rollèr of the ~pp~ratus in ~igure 2 or Figure 3.
Refer~ng fir~tly to Figure 1, in the proceg8 of Au~t~alian Patent Sp~cification 510,8~5 natural wood logs 10 ar~ first par~ially broken down, being pa~sed sucae~sively ~etwe~n ~ollers 12 o~ one or more roller p~irs to induce ~racking ~nd ~hence to progres~ively open up the lo~ ~tructurs to form it 25 int~ a we4 o~ lo~sel~ interconneated splintar-lik~
strand~ (calle~ "splinters" in Patent Sp~cification 510,~45), The resultan~ web, shown at 14 in ~igure 1 is o fl~ble open lattice work ~orm, with individua~ str~n~ ~eing connected ~o each other and 3n m~in~aining th~ original ~ra~n directlon of th~
wood. A~he~ve i~ ~hen applied to th~ web3 14 such a~ by imm~r~ion in a suitable liquid adheslve in a bath 1~ as ~hown. A~ter removal of OExce~s adhqsivs, ~or example ~y allowing the webs to drip, a plural~ty 17ti (~ L~ l)~ C~ ~ ~,JLL I :~UI`~ l~ltLI:~ . bl~ b~4 4~1~1b i' . 1~

of we4~ 14 ar~ asgemble~ to~ether, such a~ by la~in~
th~m one ov~r the other in ~ suit~bl~ mould 18. ~he aseemblage of o~erl~i~ we~æ 14 ~ th~n compres~e~ in mould 18 ~uch B~ ~y compr~ssion betwee~ th~ bas~ of the moul~l ~n~ an upper pres~ elemsnt 20 ~ ~hown, and the adh~s~ve is cur~d, to form the ~inal produçt 2Z.
Produc~ 22 i~ ch~racterised in that ~t comprises a plurality o~ woo~ ~trands whlch remaln na~urally inter~o~nect~d and wh~c~ e~ten~ ge~erally in the origin~l qrain d~rection o~ ~he wood. The st~ands are boun~ to~ether by the adhssi~e bu~ are po~itioned in ~omewhat displa~ed relative locatio~s as compared w~th the position~ occup~ed ln th~
ori~inal ~og 10. ~he p~oduct 22 ha~ been found to ~e particul~rly satifi~actory as it posse~se~ good mechanical properties, due to the reratively 3mall degradation o~ the oriqinal wood ~tructure which i8 caus~d b~ the p~ocess, as well as good n~ilability and a ~enerally pleasing appearance.
The proce~ immediately before ~e~cribed is : a batch type proce~s and Figures 2 to 4 i~lustrate schematic~lly two ~mbodimen~s appara~us for applying bonding aq~nt t~ one o~ n o~e webR 14 ~y ~
~5 ~emi-~ontinuou~ or continuouR proc~ss in accordance with the pre~ent in~entio~.
Refsrring now te Figure 2 apparat~s 24 comprises a fir~t pair of app~ying roll~rs ~6 and ~
second pair o rollers 2~ each mounted for ro~a~ion 3Q about an a~is transve~e to the direction of di~plsc~me~t o~ the web 14 through ~h~ apply~ng rollers, ~hown by the arrow 30. The roll~ 2~ and ~ m~y ~ach b~ dtiven or non driven ~nd in t~e prefe~r~d app~ratu~, ~11 of th~ applying rolle~ are Jlt~ ULLI~UN MELB. 613 654 4906 P. 14 ~ 1 driven to feed the web through the ~ppa~atu~ 2~. Tha roller~ n~ay b2 mounted in a ~l~itable frame or hath whieh ~or con-~enience ha~ not been ~hown.
E~ch of the rollers 26 and 28 ha~ the ~orm 5 ~hown ~n ~gure 4, th~t i~ witl~ a ~eml~inusoidal outer periphery wi~h peak~ 32 interspace~ by lands 34, an~ the peaks of e~ch o the pa~r~ o roller~ 26 and 2~ are oset so as to def ine a sinuous path between the roll~r~ of ~ch pair, ~hst i8 with the 10 pe~ks 32 ~f o~ r~ r Or each pair overlyins~ the l~nds 3~ of the oth~r roll~r in that pa~r. Each o th~ rollers ha~ a key~d ~pind:le 36 e~tending ~rom e~ch end of th~ ~olle~ bod~ and ls preferabl~ ~orme~
in steel or cast ~ ron . In a prefer~ed en~odiment, 15 the ro~lær body 38 has a length of ~out 440 mm an~
th~ peak~ 3~ ~n~ land~ 34 hav~ outsid~ diamet~r~ o~
about 150 and 110 mm re~pectively. ~he typical length a of e~ch land is ~0 n~n while the radiu~ b o~
the ~pex 40 o~ ~ach peak 3~ i~ typically 3 n~n and ~he 20 an~le a of each pea)~ i~ typically 23. The preferrsd range of thickne~es or ~Hpths o th~ w~b 14 a~e in tha rang~ 25 to 100 run and the preferred minim~lm nip (i.e.~ between the planes of th~ pe~ks~
between the rollerg of each p~ir 26 and 28 i~ in the range 0 to ~0 mm with the nip ~stween the ~ir~t pa~r o~ ro~lsr~ 26 b~ing advantageou~ly slightly ~reater than the nip b~tween the second pair of rollers ~8.
The ~epth of the peaks 32 may be in th* rang~ 15 to 25 mm and it will be appreciated that the rolle~s of 30 e~ch pair Z~ 3nd 28 may intsrmesh to a small degree.
Pre~era~ly only ~he roller~ 28 ~o intermesh.
Accor~insly, th~re may be only a ~mall ~e~re~ of compression c~ the web 14 between eith~r of th~ pair~
o~ rollers 26 ~n~ 2~ ~ut ~he weh 14 i8 ~t~etche~

lY~ VflJI~ ULLI~;UN MELB. 613 654 4906 P.15 ~2~39~

late~lly, ~long tha len~th o~ the rollars, by ~ollowing th~ llOUS path de~ine~ b~r th~ nip~ S4 ilS
to op~n up the lattice wor~ of the di~ete but not compl~tely sep~r~ed ~trand~ o tha web 14.
Imme~a~te~y up~tr~am o~ the ~olle~ palr ~6 in Figure 2 i~ provided means 4~ for metar~ng bonding ~genlt onto the ~b 1~ . The means 42 i~ i llu~trate~
sch~mati(:a~ly an~l compri~e~ re~pectiv~ foraminous tube~ 44 d~f;pose~ above and below the web an~
suppli~d with liqu~d bonding ~ent such ~ a tannin soïution rom ~ re~ervoir ~not ~hown) 'chrou~h a me~erinq aevice ~not ~hown) and pipe~ 46. The tube~
44 are ~lo~;e~ ~ each end and hav~ a ~erle~ o hol~s 48, s~ch as ~hown in the lower tube 44 ~ n Fi~ure ~, ope~ling 'cow~r~3 the web 14. ~he application ~evice 42 m~y h~ modified to disch~rqe foam or vapori~ed ~ bonding asent onto the web 14, The bonding ag~nt ~hu~ ~ppli~d ~o the web 14 a3 o~ immedi~tely be~ore ~he latti~e work of the web ~s opene~ up by the roller pair 2~, such opening up permittin~ the bon4in~ agenS to lnfiltrate the lattice work.
~ufflcient ;nfi~tration may oc~ur with jURt th~
roller pair 2~, but the roller p~ir 28 may b~
proY~d~d, ~Qr e~ample 25 mm down~tream o~ ~he roller pair ~6 to enhance the ~nfiltration in much t~e same m~nner as the roller pair 2~.
The su~esgive pair~ o~ rol~ers 25 and ~8 may hav~ their pe~ in line ~ut preferably to ensure optimum di~pla~ement of the ~rsndg o~ th~ web they 30 ar~ r~ vç~1~ displaced ~o that the pesk~ of ~he ~econd roller pai~ are oppo~te ~he valley~ of ~h~
ir~t roll~r pa~r.
A pair o~ xquReze rollers 48 i~ ~ount~ for par~llel rotat~on to the roll~rs 26 and 28 to r~ceive ~ 1 C ~ 1 1 ' 1 C' U~V ~ U~ I ~UI~ l ICLD . 01.~ D~ IWt r . ll~

the web 1~ dis¢harged ~rom ~he secon~ p~ir o~ roll~r~ ~8 . The ro~ leræ 4~ arc ~hos~m ~ahematic~11y but prefe~ably have a rubber or pn~umat~a ~Oay 50 whach mAy be plain or ~ently S cor~uga~d. The ~oller~ 4~ sho~lla compress ~he w~b ~4 withol~t sub~nti~lly ~re~kirA~ the i~t6~rconn~ct;on~ twe~n the st~nds o~ the we~ ~o as to s~uee~e ~2CeS~ bond~ng agent ~rom the we~.
It wi ~1 b~ appre~iated that the 40nf~inq 10 ag~nt may be ~Espl~d between th~ Lirst and ge~ond paia~s o ro11~r~ ~6 ~nd 2~ so ~hat the bondin~ agent ig appli~d to th~ ope~ ttice work. Particularly, where the bond~ n~ agent ig in the form o~ a foam, ~or e:cample a tannin ~olution which iB ~oamed with a ~S ~uita~le activator, i~ has been ~ound th~t bondlng agen~ applied downstream o~ the ~oller pair ~, or e~en downstream of both roller pairs ~6 an~ 28, iæ
ca~ried up~tr~am by the ~otatlng gurf~ce~ o~ ~he roller~ ~o a~ to also be ~pplied to the web upstream of ~he ~ir~t roller pair 26. Thus, the bon~lng aq~nt may b~ applied ~irec~ly to the web 14 between the second pair of roller~ 28 ~n~ the squeeze rollers here the foamed bondlng agent i~ applie~ in thl~ manner, it i6 preer~ble that ~he roller 26, ~A
25 an~ 4~ are aiapoæe~ in a bath to contain the ~onding agent.
~ efOErrlng now to Figure 3, the appa~atus 100 for ~pplying bon~ing agent in much the same ~ay aæ
the apparatus a4 of Figure 2 includes two 6pac~d pair~ 102 a~d 104 of applylng roller~ whi~h are e~ch driven ~nd are ~denSical to the roller~ de~crib~d with re~eren~ ~o ~igure 4 ~D includlng pe~k~ 32 and lands 34. The ~oller~ are ~upported for ro~ion ~bout respective a~e~ 36 and ~he axe~ o e~ch pair 1gl37-12-Z2 11:17 DRJIES & COLLISON 11ELB. 613 654 4906 P. 17 39~L
1~

102 and 104 iB vertically ~pa~ed. The peak~ ~ of the roll~r psir 102 proje~t into a common plane at the nip 106 80 do no~ in~erme~h while the pa~kæ of roller pair 104 do intermesh ~lightly a~ shown at the nip 108. ThQ ~eakR 3~ of the applying roller~ in each pair are of~et one relative to ~he othe~ and the peak~ o the rollers ~02 are off~at relati~e to the pe~ks o~ th~ rollers 104. The bottom roller~ in each pair 102 ~nd 104 rotate in a clockw~se ~ csion wh~e the top ro~lers in each pair 102 and 104 rota~e in ~n ~nti-cloc~w~e ~irec~ion æo as ts disp~ace a web through th~ nips 106 ~n~ 108 from left ~o right in ~he dr~wing Up~tream of the rolle~ pair 10~ i~ a pair o~
lS drive roll~r~ 110 which are ~lain and supported for rotation d~out a~iæ 11~ to define a nip 114 which lies in a Common plane with the nip~ 106 and 108~
~he ~ri~e rollers 110 a~e driven to rotate in the same re~pective directions a~ the roller pair~ 10~

2~ and 104 ana ~re intende~ to force the web into the nip 1~6.
~ tween the pair of dr~ve rollors 110 a~d the p~ir of a~plyinq roller~ 102 thare i~ æuppo~ted a ~upp~rt rollar 116 for ro~ation about an a~i~
pa~ l to the a~ec 36 a~d ~12 but below the plane of ~he nips 114, 106 and 108. ~h~ suppor~ roller 116 is spacea fsom the lower drive roll~r 110 and the lower applying roller 102 by approximately 5 mm and may have a diame~er in the range of for example 50 ~o 70 mm. The primary purpofie of ~he support rolle~
i~ to prevent ~mall ~epara~ed ~r~n~B from drop~ng out of ~he we~ ween tha roller pair~ but i~ ha~ a ~econ~ary function which will be de~c~ibed in due course.

JHVIt~ ULLI~UN l~ltL15. bl:5 b~4 4YIC11~ 1'. 1~

~ ~'7~9fi'1 Downstr~am oF the applying roller pair 104 is a pair o ~queez~ rollers ll~ which are ~180 dri~en to rotste about r~spective a~es ~20 p~r~
to the ase~ 36 and 112 ~o that th~ nip 122 l~s ~ n 5 the com~on plvn~ of the nipg 106, 10~ an~ 114. ~he squeeze rollers 118 are al~o ~riven to rotat~ in the ~ame re~p~ct~v@ dire~tion~ ~ the apply~ng roller8 an~ th~ drive roller~ nnd may otherwi~e be ide~tical to tha ~qu~e~e roll~r~ ~8 ~o w~ll not ~e ~escrlb~d 0 further.
A second support xoller 124 i~ mounte~ ~or rotation about an axi~ p~rallel to the other de~cribed ~es and below the plane Of th~ nips. ~he ~upport roll0r 124 ~a~ hav~ a ~iameter in the range 50 to 70 mm and i~ 5hown ~paced from ths 40ttom squeeze roll~r llB ~y ~oUt 5 mm while ~lmo~t touching the lower ~pp~ying roller 104. ~gain, the pr~mary function of the support roller 1~4 is to prevent ~mall ~eparated ~trand~ ~rom droppin~ out of the web a~ it passe~ through the apparatus 100 bu~ it has e ~econd~ry purpo~e wh1ch will b8 descri4ed herein~fter.
~ 11 o~ the pairs of ~sller~ 102, 104, 110 and 118 and the support rollers 116 ~nd 124 are supported fo~ rotation in an open en~ed baSh 1~6 ha~ng a bottom 128, sides 130 ~only one shown) and at l~a~t a pa~tial down~ream end 132, The bath ~6 is inten~ed to contain the bonding agent, pre~erably in a foam form, as will ~e describ~d in mo~e detail hereina~ter~
A~ the down~ream ~nd, a Con~eyor b~lt 134 shown onl~ in part is supported or ~i~placement on ~paced rollers 13~ ~one only ~hown) to reeive the co~te~ and ~pread web ~rom the bath 126 for onward LH~ BULL I ~UN r'ltL8. 613 65~ 4906 P . l~l 8g61 pro~esslng for e~ample ~ ~escribed with re~erenS~e to Fiquxe 1. Tha conv~yor 13~ is dispase~ within a hougin~ 13~ bu~ ~his snd the conYs~or 134 Inay ~ak~
any s~it~ble form ~nd w~ll not ~e des~ribad Çur~h@r, 5 A third ~upport roller 1~0 i8 ~upport~d for rotat~or about ~n a~l~ p~r~llel ~o the other descriibed ~o~
betw~en th~ lower ~gueeze rol ler dnd ~he ad~ 2c~nt con~eyor rollex 1~5. The purpoge o~ the third ~upport roll~r 140 i al~o to prevent small sep~rated 10 str~nds from ~ropp~nq out o~ the coated and spread web .
Ag noted already, the ba~h 1~6 is ~r~marily int~nde~ to t~ke oam bonding agent ~ ich may be aB
previou~l3r desar~bed and this may b6s introduced to 15 the bath in ~ b~tch manner or ~ire~tly onto th~ ~e~
within the batl~ immediately ups~e~m o the apply~ing roller~ 102 or el~ewhere up8tream of the sSluee~e .
roll~rs 118. The ~qu~e~e roller~ 118 ~queeæe ~sce~s bon~ng agent out of ~he impre~neted web and it is 20 ound that the excess is ~rawn by the anti-clockwi~e rotation o the upper rolle~s 102 and 1~4 over~ th~
top ther~f back to u~stream o the roller pair 102 where~ its re~urn passage is blocked ~y a parti~l wall 142 e~ten~lin~ acro~ the bath abovs the plane of the 25 nip~. A ~im~lar mo~ement of t~e e2~cess bol~ding agent is caused between ~h~ bottom roller3 102 and lo~ and the ba~e 1~8 of the bath 1~6 and the ~eturn pa~sa~e of ~h~ portion of the e~cess bonding agent is prevent~d l:-y a p~rtial wall :l44 e;4tending across the 30 width of th~ bath between ~he ba~e 12~ and the iræt support roll~r 116. ~ well 146 in the ba~e 12~ o the bath allow~ a ~reater volum~ of bonding ag~nt to be ~ccommodated ben~ath the rolleræ 1~2 and 104.
It h~s ~een found that even be~ter lY~ lY ~ vlt~ ~ ~,ULLI~iUN MtL~. 613 654 4g06 P.20 impr~3gnation o~ ~be web i~ c~u~d by th~ provi~ion of a æhroud l~ hich extends across th~ width of the bath f rom imme~ c~l3r adj acen~ the ir~t support roller 11~, b~n~ath ~n~ p~rtly around t~e bo~ton~
5 ~pplyin~ roll~r 102 to l~etween the bo'ctom rollers 102 and 104, ben~atll an~ partly around the bottom ~oller 104 to ~djacent the second ~upport roller 124 and the bottom s~uee~e roller 118~ The shroud 148 e~ en~ in clo~e prosisnit~ to the lower arc~ o~ th~ bottom rol~er~ 10~ an~ 104 but exc~ss bonding agent is carried ~dtacent ~he ~hroud between the peak~ 32 o~
the bottom applying ~oll0rs. A 1~red lip 150 def ine~ a ~unn~l to rec~i~e ~xcèss ~ondin~ agent f rom between the second support ~oller 12~ and the bo~tom squceze roller 118.
rhe roller pAir~ 102 and 104 are ~hown relati~fely clo~ely spac~d and ~n pr~ctice this spacing msy be of the or~er o~ 25 mm. In a mo~i~ic~'cion, th~ roller pairs 102 ~nd 104 may ~e ~o spac~d b~ a ~other greater di~tance such as the spacing betwe~n ths drive ~ollers 110 and the - applying roller~ 10~ snd a similar support roller m~y be di&po~ed betw~en the bottom roller~ 102 an~ 104.
The ~escribed meth~d and apparatus have been ad~anced merely by way of e~planation snd many modi~icatio~s ~n~ vari~tions may be made thereto withou~ departing rom the spirit and ~co~e of the ~nvention a~ defined ~y the ~PPended c~aims~

~0 .

Claims (43)

1. A process for applying a bonding agent to a flexible open lattice work web of naturally interconnected wood strands prior to compressing and consolidating said web to form a reconsolidated wood product, said web being formed by partially rending natural wood so that said strands are generally aligned along a common grain direction with a substantial proportion of said strands being substantially discrete but incompletely separated from each other, said process comprising passing the web through a pair of applying rollers of which at least one roller is corrugated whereby a portion of the web passing through the applying rollers at any one time is spread laterally without substantial further separation of the strands, applying bonding agent to said portion of the web immediately prior to its passage through the pair of applying rollers or while the portion is spread by the pair of applying rollers and removing excess bonding agent from the web downstream of said applying roller pair.

2. A process according to claim 1 wherein both rollers of the applying roller pair are corrugated and the peaks of the respective rollers are offset.

3. A process according to claim 1 wherein at least one of the applying rollers is pneumatic.

4. A process according to any one of claims 1 to 3 wherein the or each corrugated roller of the applying roller pair has substantially sinusoidal peaks with lands between the peaks.

5. A process according to claim 1 wherein a second pair of applying rollers is provided upstream or downstream of the first-mentioned applying roller pair.

6. A process according to claim 5 wherein at least one roller of the second pair of applying rollers is corrugated.

7. A process according to claim 6 wherein the peaks of the at least one roller of the second pair of applying rollers are offset from the peaks of the at least one roller of the first-mentioned pair.

8. A process according to claim 5 wherein the nip of the second pair of applying rollers is less than the nip of the first-mentioned pair.

9. A process according to claim 6 wherein both rollers of the second pair of applying rollers are corrugated and the peaks intermesh.

10. A process according to claim 1 or claim 5 wherein all of the applying rollers are driven.

11. A process according to claim 1 wherein a pair of driver rollers is provided upstream of the applying roller pair.

12. A process according to claim 5 wherein a pair of driver rollers is provided upstream of the applying roller pair or of the upstream applying roller pair.

13. A process according to claim 11 or claim 12 wherein a support roller is provided between the drive roller pair and the applying roller pair or the upstream applying roller pair to support the web between the drive roller pair and the applying roller pair or pairs.

14. A process according to claim 1 wherein the means for removing excess bonding agent is a pair of squeeze rollers.

15. A process according to claim 5 wherein the means for removing excess bonding agent is a pair of squeeze rollers.

16. A process according to claim 14 or claim 15 wherein the squeeze rollers are formed of rubber or are pneumatic.

17. A process according to claim 14 or claim 15 wherein a support roller is provided between the applying roller pair or the downstream roller pair and the squeeze rollers to support the web between the applying roller pair or pairs and the squeeze rollers.

18. A process according to claim 1 wherein at least the applying roller pair is mounted for rotation in a bath.

19. A process according to claim 5 wherein at least each applying roller pair is mounted for rotation in a bath.

20. A process according to claim 18 or claim 19 wherein the bonding agent is introduced to the bath downstream of a position immediately upstream of the applying roller pair or the upstream applying roller pair and is carried to said immediately upstream position by the rotation of the applying roller pair or pairs.

21. A process according to claim 18 or claim 19 wherein at least a bottom roller of the or each applying roller pair is corrugated and a shroud extends immediately beneath the or each said bottom roller to guide bonding agent upstream of the rotating applying rollers.

22. A process according to claim 1 wherein the bonding agent is a foam.

23. Apparatus for applying bonding agent to a flexible open lattice work web of naturally interconnected wood strands formed by partially rending natural wood so that said strands are generally aligned along a common grain direction with a substantial proportion of said strands being substantially discrete but incompletely separated from each other, said apparatus comprising a pair of applying rollers adapted to receive the web therethrough, at least one of the rollers of said pair having a corrugated outer surface whereby to define an extended path for the web across the width thereof and to thereby open the web, means for applying bonding agent to a portion of the web immediately upstream of the applying roller pair or to the opened portion of the web, and a pair of squeeze rollers for removing excess bonding agent from the web.

24. Apparatus according to claim 23 wherein both rollers of the applying roller pair are corrugated and the peaks of the respective rollers are offset.

25. Apparatus according to claim 23 or claim 24 wherein at least one of the applying rollers is pneumatic.

26. Apparatus according to claim 23 wherein the or each corrugated roller of the applying roller pair has substantially sinusoidal peaks with lands between the peaks.

27. Apparatus according to claim 23 wherein a second pair of applying rollers is provided upstream or downstream of the first-mentioned applying roller pair.

28. Apparatus according to claim 27 wherein at least one roller of the second pair of applying rollers is corrugated.

29. Apparatus according to claim 28 wherein the peaks of the at least one roller of the second pair of applying rollers are offset from the peaks of the at least one roller of the first-mentioned pair.

30. Apparatus according to claim 27 wherein the nip of the second pair of applying rollers is less than the nip of the first-mentioned pair.

31. Apparatus according to claim 28 wherein both rollers of the second pair of applying rollers are corrugated and the peaks intermesh.

32. Apparatus according to claim 23 or claim 27 to 28 wherein all of the applying rollers are driven.

33. Apparatus according to claim 23 wherein a pair of driver rollers is provided upstream of the applying roller pair.

34. Apparatus according to claim 27 wherein a pair of driver rollers is provided upstream of the applying roller pair or of the upstream applying roller pair.

35. Apparatus according to claim 33 or claim 3 wherein a support roller is provided between the drive roller pair and the applying roller pair or the upstream applying roller pair to support the web between the drive roller pair and the applying roller pair or pairs.

36. Apparatus according to claim 23 wherein the squeeze rollers are formed of rubber or are pneumatic.

37. Apparatus according to claim 23 or claim 27 wherein a support roller is provided between the applying roller pair or the downstream roller pair and the squeeze rollers to support the web between the applying roller pair or pairs and the squeeze rollers.

38. Apparatus according to claim 23 wherein at least the applying roller pair is mounted for rotation in a bath.

39. Apparatus according to claim 27 wherein at least each applying roller pair is mounted for rotation in a bath.

40. Apparatus according to claim 38 or claim 39 wherein the means for applying bonding agent introduces the bonding agent to the bath downstream of a position immediately upstream of the applying roller pair or the upstream applying roller pair whereby rotation of the applying rollers is adapted to carry the bonding agent to said immediately upstream position.

41. Apparatus according to claim 38 or claim 39 wherein at least a bottom roller of the or each applying roller pair is corrugated and a shroud extends immediately beneath the or each said bottom roller to guide bonding agent upstream of the rotating applying rollers.

42. A process for forming a reconsolidated wood product from a plurality of superposed flexible open lattice work webs of naturally interconnected wood strands, each of said webs being formed by partially rending natural wood so that said strands thereof are generally aligned along a common grain direction, a substantial proportion of said strands of each web being substantially discrete but incompletely separated from each other, said process comprising applying bonding agent to said webs, superposing the webs, compressing the superposed webs to consolidate the strands and curing the bonding agent to bond the strands and webs together, said application of bonding agent comprising passing each web through a pair of applying rollers of which at least one roller is corrugated whereby a portion of the web passing through the rollers at any one time is spread laterally without substantial further separation of the strands, applying bonding agent to said portion of the web immediately prior to its passage through the pair of applying rollers or while the portion is spread by the pair of applying rollers and removing excess bonding agent from the web downstream of said roller pair.

43. A reconsolidated wood product when formed by the process of claim 37.