dJrl qGi'7 I= EXTERIOR STRU- GWFw

Peter Vajda, President Colmhia Engineering International Ltd. Vancower , Canada

Abstract "strands" are flakes hose length is at least 3 to 4 tines greater than their %is paper sumMlrizes the history and tech- width (the slenderness ratio is essen- nology of structural flakeboard IMnufacture and tial for orientation) the currently ongoing research work aimed at bpmving and/or reducing the axt of the pre- Saw sources refer to structural particle- sently marketed products. !Ihe basic mqara boards as stnlctural flakeboards mainly tive emnanics of the product, or its ampti- because the use of flake-type particles is tive position against softwood plywocd are dis- thought to be essential for the manufacture of used and evaluated. It is concluded that an exterior structural grade product. The structural flakebards present a good opportu- term structural particleboard is used by those nity to supplement the diminishing softwood who do not wish to pre-judge the ned for a plywood supply in the housing construction and specific kind of particle in order to acfiieve saw industrial markets. structural properties.

First, let m make an attempt to clear up As the term "particleboard" is closely SOE uncertainties as to the terminology of associated with the industrial gra& and "structural grade particleboards" or "flake underlayrnent grade particleboards manufactured boards". at present by the industry wit!! uF resins, for interior applications, for the purposes of Structural grade particleboards are called differentiation 1 will use in this paper the by saw sources "particleboards" by others term structural flakeboards as designating a "flakeboards" and still by sm others as product which is made with exterior grade "waferbard" or "stranM". All these terms resins (PF or other) and having properties refer mainly to the types or kinds of particles suitable for structural and exterior applica- which are being used in the manufacture of an ticms. This terminology is not intended to exterior grade reoonstituted wood panel product. exclude the possibility that structural pro- We will therefore have to agree on terminology perties may be achieved by using either "semi- before atknpk-ing to analyze the technology and flakes" or even "randm particles" in say the emanics of manufacturing these products. axe of a structural grade panel.

In the follming paper, I propose to use History the follming terns: Structural grade flakeboard or the idea of particles are used as a generic term for structural grade flakeboard has been mund any kind of wccd particles be they randan for a long time. or of specific length, width, thickness parallel to the grain or at right angles Almost all the original particleboards in to the grain Europ in the late Forties and early Fifties were made with flakes and were aired at flakes are particles which are cut para- optimizing bending strength and stiffness. llel to the grain (that is, tk cutting They were hawever manufactured with urea knife is parallel to the grain) resins and were therefore interior rather than exterior grade products. The use of smller "semi-flakes" or "chip flakes" are flakes flakes or randan particles or semi-flakes and cut fran pulp chips by a ring type flakec the enphasis on surface cfiaracteristics and sine the pulp &ips are essentially cut 3ntemal bond properties cam at a later date, across the grain, the resulting flakes probably after 1960. will also have a cross-grain feature In North America, one of the first par- randcm particles are particles cut fran ticleboards introduced was "Novoply" which shavings, sawdust and other mill residue, used flakes in the surface layers of the or even chips, by a hamwrmill or hog board and had potentially structural proper- type macfiine ties with the exception that it was again made with urea resins. "wafers'' are large, square flakes as used in "waferboard"

427 In the early Fifties, Dale Turner working approval in the construction of haws and 2 ' at the Forest Products Laboratory in Madison, Story apartment buildings. Wisconsin, explored the effect of flake am- figuration cm board properties and shaed that In 1969, MaMillan Bloedel doubled its structural or plymod-like properties are capacity at Hudson Bay, Saskatchewan. In the adievable with suitable flake canfiguraticm. 1971 to 1974 period, four mre waferbard His paper published in 1954 is probably one of plants =re built in Canada - three in the classics in North Amrican particleboard Bay, Ontario and one at Ti.", Ont. literature. At the present, waferboard in Canada is In 1954, Jim d'Arcy Clarke presented a produced at a rate of about 500 to 550 PMsf paper to an mseting in Seattle introducing 3/8" per annun rate. About half this pro- the concept of a "waferboard" product and a duction is sold in Canada while half is waferboard plant. The research and pilot plant exported to the northeastern and northcentral mrk on this project was carried out at United States. The Canadian mnsmption of Washin- State University Wood Products waferboard is about 12%to 13%of Canadian Laboratory at Pull.", Washingbn and, by 1958, softwood plywood consmption. a waferbard plant was in operation at Sand- point, Idaho. The developent of a structural flake- board, or a substitute for plywoodr proceeded The introduction of a waferboard or struc- in the united States at a much slaver pace tural flake!xard product in 1958, haever, was than in Canada, in spite of the fact that the not timly. North An-erica had an abundant expansion potential of the U.S. plyklwa supply of law cost peeler logs and sheathing industry in tenus of available sof-twood peeler grade plywd. ?he cost advantage of wafer- log supply in the U.S. is mu& mre limited board against sheathing grade plywood was and is probably approaching its ultimate level. marginal, especially sine the Sandpoint plant was located in the northwest region along with In the early Seventies, Potlatch Forests all the plymod plants. As a result, the Inc. built a pilot plant to prove the techni- Sandpint plant did not succeed in petrating cal and marketing feasibility of Oriented the structural sheathing grade plywlooa market Strandwad based on the Elmendorf process. and the pmduct was sold mainly for deaxative Using this technology, Potlatch opted for the end uses. manufacture of a cross-oriented core board for use in the "facture of a ccmposite The late Fifties and early Sixties also saw flakeboard/plywcod product nmd Plystran. the experinentation and pilot plant work Also in the early Seventies, Blandin Paper at carried out by Armin Elmendorf, attapting to Grand Rapids, Minnesota built a waferboard work out a process for the manufacture of plant based on the Clarke process. This plant oriented flakeboard or, as it is nw called had considerable start-up difficulties but is "Oriented StranM". John Talbot at now reported to be in full production and is Washington State University also carried out marketing the product successfully. sminvestigations on flake orientation and the properties of such an oriented flakeboard Time and spa= do not permit the enwr- product. ation here of all the research and pilot plant work that has been carried out in relation to In 1963, another waferboard plant was built structural board during the past 10 years by in Hudson Bay, Saskatchewan, based on Jim various institutions in North Amrica. All Clarke's process and concept. This venture of these mncepts hmever would require con- also failed under its initial mership and siderable additional work in order to be management. It was first taken over by the jumed as fully practical and qel-ational. In Govenwnt of Saskatchewan and eventually sold view of the expected increase in North Ameri- to Madillan Blcedel Ltd. of Vanmver, B.C. can dernand for structural grade wood p-1 Under MacMillan Bloedel's magmnt and sales prcducts coupled with the impending shortage efforts, the wafertx>ardprcduct found its way of softwood peeler log supplied in the U.S. r into the structural sheathing grade markets in the demnd for structural flakebard products ccanpetition with plywood, mainly based on its in the U.S. should accelerate in the next 5 freight advantage against West Coast plywoOa years resulting in increased plant con~tru* in Canada' s mi&estern Prairie markets. tion and the introdudion of ww structrual products and prcduct variations into the U.S. The first applications penetrated by markets. waferkmard in the Prairies were in the con- struction and rermdelling of farm buildings, The Properties and Technology of C-cially fences and other general utility applications. Produced Structural Flakeboards In these applications, the pmduct proved itself to be satisfactory as an exterior Just what dc we mean by structural flake- grade parel. As a result, it received Cock board? In sinple terms, vie are aiming at a

428 prdducrt which auld replace exterior sheathing It should be mted here that waferboard as grade (mnstruction grade) plywoOa or the stan- it is produced at the present has a powdered dard CDX grade plywWa marketed in the U.S. phenolic resin content of about 2.5% to 3.0%. Other applications and end uses are possible, A sliFpltly higher resin mtent (3.5%) pawder- even probable, but in all Likelihood the ed resin or 6% resin solids in liquid form initial market penetration will have to be made wuld improve all strength properties by at sinply as plywood replamt. least 20%. The product hmever has performxl and sold well in its present fop and the It is of interest therefore to s"rize mufacturers did not see any need to umrade here the significant praperties of "CDX" or improve. Probably the market accepted the plymod. In general and sa"t dpp&tt? waferboard prcduct - in spite of 1mr terms these are: - modulus of rupture (bending physical properties -- because it is mre strength) - along the grain 8,000 psi, across uniform and has less surface defects than the grain 4,000 psi; rrociulus of elasticity plymod made with "C" or I'D" grade vc-rs. along the grain 1,200,000 psi, across the grain 500,000 psi; linear expansion (30%to 90% The other strucbxal flakebcard product relative hmidity) - along the grain .lo%, which is nearing introduction in North Amrica across the grain .14%. is "Strw". It is made with elongated flakes, called "strands" , which are oriented These are the ge=ral properties of "ax" (mchanically) in the fonning operation. The plywood although it is seldan expressed in this faces are oriented along the panel direction mr. The plmspecifications are mainTy and the core across the width. The product is concerned with the quality and efficiency of a developrent of Elrnendorf Research Inc. the glue line in terms of glue vs. wood failure Potlatch Forests has a semi-production type in the standard tests. In addition, they are pilot plant operating at kwiston, Idaho. also aimed at mtrolling veneer quality in relation to the various plywood grades. %e ?roperties of "Strandwood" (as achiev- ed in the pilot plant and using 5.5 to 6.0% Using "C" and "D" grade veneers and a resin solids in liquid form) are mch closer standard glue line and gluing procedures, as to plywoOa; along the grain an m.0.r. of in the CDX grade (fir veneer) product, we will 8,000 psi, m.0.e. of 1,000,000 psi and linear get properties sawhat similar to those given expansion of 0.11%; across the grain m.0.r. above. We will also get a panel which retains of 2,500 psi, m.0.e. 35G,OOO psi and linear about 60% to 70% of its original strength under expansion abaut 0.16%. The market aqxrience severe long term exposure to weather or under with the product is limited but it appears to tests which sirmlate such exposure. have great pranise.

One should also note that these proprties Aqain, the above properties relate to a are achieved at a panel density of 36 lbs/ft3 density of 42 lbs/ft3 (.65 specific gravity) or .58 specific gravity. when using softmods or lm density hardwoods.

Can we achieve or approximate these proper- We may conclude fm the above that the ties with the present structural flakeboards? technolcqy for the manufacture of a semi- structural grade flakeboard, namely "wafer- The "waferboard" product as it is mufac- board", exists and is proven by 7 operating tured today does approximate plywood's "acmss plants. Furthemre, the product has been the grain" properties. Since it is a product -11 ac(Xpted by both Canadian and U.S. using large, almost square, flakes ("wafers") markets. Admittedly, waferboard is not a fomd in a random manner, the product has no fully structural product inasmuch as it has "grain" and the properties are the smin lmer strength and stiffness properties than both pard directions. CDX plywood. The strandwood or oriented flakeboard Process des hmever yield a product "ercially produced waferboard has an m. whose praperties nearly or fully equal the 0.r. of about 2,500 psi, an m.0.e. of 450,000 strength and stiffness properties of plywood. psi and a linear expansion of about -15% in The technology in this regard exists, it is both panel directions. Its strength retention similar to the one used in the manufacture of is well over 50% after the standard 6 cycle waferboard and is also proven out in the pilot weathering test and field experience with the plant operation of Potlatch at Lewiston. product in exterior applications is excellent. ?he density is 42 Ibs/ft3 or .65 sp g. It is to be noted here that all presently manufactured waferboards are made €ram aspen Both the Canadian and U.S. Building Codes roundwcd. Other species have been tried in approved waferboard for use in roof decking and laboratories and pilot plants with varying subflooring, but it has to be 1/16" to 1/8" degrees of success. The use of other Species, thicker than plywood in the sane use depending especially heavier density hardwoods, in the on support spacing. manufacture of waferboard therefore cannot be

429 called at the present fully operational. The Hanbak YJ" type flakers capable of, ' accepting tree length logs for flaking are an Potlatch at -ism is using "maxi--dlipsll interesting alternative for the mufacture of or large &ips made frcm western softmod flakes or "wafers". These machines are used species A the manufacture of its cmss-orien- extensively in Eurape but have not been selec- ted OOZ. In all probability, all softwood ted by North Amrican waferboard or stranM SEEC~Sand sare law density hardwood species plants to date. would be suitable for the mufacture of wafer board or oriented strandwood when using true The flakes are dried in ODnVentional flakes, wafers or strands which are cut frun particleboard dryers of the 3 pass or single mundwood. 'Ihe suitability of semi-flakes made pass drcnn type (Heil, ME€, Guaranty Perfor - frun chips or maxi-chips is questionable at the mance). Up to the present, these dryers have present, especially as it affects dirrrensional been fired by natural gas or oil. Nm, mt stability. At the pnxient state of tedmology, plants are rapidly converting to the firing of true flakes (wafers or strands) will have to trim waste and fines with the resultant and be used at least in the surface layers of a well knm misture aontml, fire hazard and structural panel in order to achieve satisfac- emission control problems. tory strength and dimensional stability properties. The binning of dry or wet flakes or wafers must be given specid attention since the The Manufacturing Technique of Waferbmrd flakes or wafers bind or bridge'in bins to a mudl greater extent that particles. Miller Waferboard is mufactuyed by a process Hofft H type bins, or similar Units, have which is dlmost identical to the one used for proven to be the mt satisfactory an3 least the manufacm of industrial grade flakeboards troublesm in the b-g and feeding of &nly in Eurape but also by the early North flakes, wafers and strads. Amrican flakeboard or particleboard plants. All waferixwd plants use a large, slwly The wafers or large flakes are made on rotating drum for the blending operatian, either clisc or drum type flakers. Prior to partially in order to prevent an excessive flaking, the mundwood is put through a thaw breaking cr splitting of the flakes and/or pond or mditioning chamber partially to thaw wafers. The manufacture of waferbad does the mod during the mld winter mnths in the require that the large wafers "sin as intact mrthem U. S. and Canada but also to soften as possible throughout the manufacturing the wood for better flaking. All presently operation, partially to Etain the typical operating waferboard plants debark their wood wafertxwrd-like appearance of the product for prior to flaking. reasons of marketability but also in order to "ize resin consuption. The high speed Most operating wafe-d plants use a disc smll blenders used in the manufacture of flaker made by CAE in Vancouver, B.C. Saw, particleboards are thought to cause excessive notably Great Lakes Pulp & Paper in Thunder wafer splitting and higher resin requimts. Bay and Waferboard Ltd. in Thnhs, Ontario Unquestionalby, high speed blenders do cause use a drum flaker made by Betmer. The H&ak wafer breakup. The contention that as a "Z" type drum flaker would perfom the sarfe result of this, resin consumption would function. increase significantly is however questionable.

Disc flakers are thought to produce more Potiat& at miston in the mufacture of accurate flakes or wafers and gemrate less the mss-Orimted board does use high speed fines than drum flakers. They do require hm- blenders of the Keyston type in connection ever that the logs be slashed to a fairly with liquid phenol resin. Here, the breakup accurate 2' length. This slashing operation is of the larger flakes into strands is desirable. very cun-bersane and generates a relatively high It is reprted that the fines and short peroentage of small "lily pads'' which cannot he strands generated by this high speed blender used in the flaking operation and are wasted. are presently higher than intended. %sin amsunption hawever is a highly acceptable flakers can use logs up to 54" in 54 to 6% solids. length but also accept logs down to 3' or 34' lengths. This results in a less cmrrbersm The first waferboard plants used a fo&g slashing operation and a mini" reject factor machine specially designed by Jim Clarke for in snall "lily pads". Adnittedly, drun flakers the forming of wafers. Later, Ma&iillan do produce a higher percentage of fines. This Blcedel and Weldwood of Canada installed a -ever is balanced by a mu& lesser percentage sdatmre conventional fomr designed of lily pad rejects. Drm flakers also have a ad manufactured by Dura in Vanmuver, B.C. m& higher output capacity than disc flakers The Great Lakes Paper plant at Thunder my and and are therefore mnsidered to be a mre Waferboard Ltd. at Tirmcins use a sawwhat practical machine for actual plant operations. modified Wurtex forming machine from Germany-

430 ' AWtany of the European forming md-hes The above will serve to hi@li*t the (Wurtex, Schenck, Bism, Fahrni) are thought to manufacturing techniques applied in the pro - be suitable for the forming of wafers, flakes ductim of wafaboard, especially inasmuch as or strands since they were originally designed they differ fran the mventional particle- for the fonning of relatively large flakes. board manufacturing tedmiques. Some adjusmts and modifications in these formers waild hme to be inplemntea to handle current DeVelO~ts the different flake sizes. Potlatch uses a specially designed noss-orienter and fomr At the present, a substantial munt of for the manufacture of their mss-oriented research is being carried out dealing with the axe board. For the forming of oriented mdifications of and hpmvarents to the basic strandmod or oriented flakeboard, all of the structural flakeboard mept. Investigations above nand forming machines wwld be suitable are being carried out with regard to the use if equipped with an orienting device. of different mod species, various board mn- struction and configuration, new mthods of At the present, three basic orienters are flaking and the use of new and different available. The first one is a mchanical type resins and resin extenders. To the knowledge orienter designed and patented by ElnEndorf of this author, the mt significant work of and currently manufactured by Bison in Germany. rather Mateinterest includes the The second is an electrical orienter manufac following: tured and supplied by Voltage Systems Inc. of Portland, Oxegon. Both these orienters have 1. The use of semi-flakes made from whole been successfully tested in pilot plant opera- tree &ips or chipped forestry waste tions although neither has been proven in and logging slash in the mufacture actual cnmercial plant operations. The third of structural board products. This is orienting device is the cross-orienter designed an extensive project carried out by the by Potlatch and cun-ently manufactured ard Forest Products laboratory at Madison, supplied by Ledcenby of Seattle, Washington. Wisconsin. This is the mly orienter in actual 24 hours/ day plant operation in North America. 2. Mike Hunt's project at Pixdue University in Indiana dealing with the ccnceptual It should be noted hm that the electrical design of a 1-1/8" thick roof deck orienter supplied by Voltage Systms is repop product made fran red oak flakes. ted to have been installed in 2 operating plants in Europe and is sucocssfully orienting 3. ?he manufacture of flakes by mans of industrial grade flakeboard made with urea a shaping lathe carried aut by Peter resin. Koch of the Forest SeMce in Louisiana.

The mat handling and pressing operation of 4. The use of isocyanate resins in the waferbard and strandmod is morn4by the mufacture of a structural exterior ccnventional caul system coupled with the grade flakeboard products. This work nulti-apening press, loader and unloader unit. is being carried out by a nuher of Specific press pressures required are in the researders in a nuher of Laboratories. order of 500 to 600 psi. For the mufacture of waferhard using powdered phenolic resin, 5. The use of dried and powdered coniferous press tenperatures in excess of 4009 are foliage as an extender to phenolic mcessary for the achievcmmt of satisfactory resins in the manufacture of wafer board properties and acu=ptable curing tin?? board (and plywood) carried out by cycles. I", when using liquid phenols, Suezone Chw at the Western Forest 1-r press temperatures (say 350 to 3750F) a Pmducts Laboratory in Vancouver, B.C. Progress reports have been received on all of The swing equipnt used by waferbard or these projects at various FPRS mtings and stra"d plants is similar to that used in at the Particleboard Symposium at Pullman. the manufacture of industrial particleboard. lhey are of significance because they are Presently operating waferbard plants do not at-ting to achieve substantial savings in have sanders as the pressing operations are either wood casts or resin costs in the mu- sufficiently accurate to yield an unsanded facture of structural flak- products and product within the required and acceptable would also result in the greater utilization thickness toleranas. It is highly probable of the existing North forest resource that in the future structural flakeboards, waferbard or strandwood products will find Space does not pennit a detailed evalua- their way into applications where thickness tion of these projects. For detail, the variations my have to be keptwithin closer reader is referred to the reports published limits. Caxeqwntly, future plants may in the FPFS Journals and the proceedings of have to install sanders. the Pullman Particleboard Symposium.

431 The author did however prepare conceptual In order to deal with the great nmrof' plant designs and capital cost estimates for variables, the plant was broken dam into plants turning out a structural grade flake- apprapriate sections su& as the raw material board product as determined by the investiga- handling and flaking section, the wing and tions of the Forest products Laboratory at blending section and the fonning and pressing Madison. It is ansidered to be appropriate section. The raw material handling and fla- therefore to report here in sunmary form on king sectim was designed to handle and/or the results of this study. flake each raw material form such as shaping lathe flakes, whole tree logs and whole tree Conceptual Plant Designs for the Manufacture of or forestry chips. Each handling and flaking Structural Flakeboards as Devekped by the section was designed to handle and flake the Forest Products Labaratory - Madison, Wisconsin various raw materials at the designakd plant capacities. Similarly, the drying an3 blen- The essential finding of the Madison ding section was designed to handle the resear& work was that a structural grade material flow at the designated plant capaci- flakeboard of acceptable properties my be ties. The forming and pressing sectim was mufactured by using semi-flakes ma& fm also designed for the designated plant out- whole tree &ips or chipped forestq waste in puts at a number of press sizes and configur- the axe of the board and true flakes made fm ations. ra"d in the face. In other words, it was found that the use of "chip flakes" or "Semi- Figures 1, 2 and 3 shcw the basic section flakes" in the mre would etin an insig- flow sheets for the handling and/or flaking of nificant deterioration of strength ard shaping lathe flakes, whole tree logs and dimensional stability praperties when measured whole tree &ips or forestry chips, against similar properties of a baard made respectively. entirely fran true xomciwcod flakes. Figures 4 and 5 show the basic section Based on this finding, a board construction flw sheets for the drying ad blending of was devised mnsisting of 60% "chip flakes" to the raw materials. The drying and blending be plaaed in the core of the board and 40% true section flow sheet DB1 refers to the use of flakes to be used in the face layers of the 100% shaping lathe flakes at the 50 MMsf 3/8" board. As a result, the raw material supply per annum output capacity. Flow sheet DE32 oonditions set out for the plant design were refers to the raw material inpt anditions of as follows: 40% flakes in the face (either fran whole tree logs or lathe flakes) and 60% chip flakes in 1. 40% of raw material demand in the form the axe. The nurtber of dryers and screens of tree length logs; 60% of the demand and the size of the bins and blenders are in the form of whole tree chips varied depsnding on phtoutput. Similarly, the nupnber of ring flakers in Figure 3 ('I* 2. 40% of the demand in true flakes fran a WF3) is also varied deperdhg on plant output shaping lathe operaticm; 60% of the demand (one flaker at the lmest output and 4 flakers in whole tree chips at the highest output). The plants were designed for 4 differing In the case of the whole tree length log output capacities: supply and drum flaking (Figure 21, the smallest available drum flaker oonsidered ta 50 mf 3/8" per a" be of practical use in an operating plant had (about 35,000 O.D. tons/year) sufficient capacity to handle the output of the largest unit. ?is a result, the smflow 0100 Wf3/8" per annum sheet and the sarne nunher of flak- apply to (about 70,000 O.D. tons/year) all plant outputs; only the size of the soaking ponds or anditioning chanbers is 0150 mf3/8" per annum varied dewgon plant output. (about 105,000 O.D. tons/year) In the case of the shaping lathe flake 0 200 MMsf 3/8" per annum supply andition, no flakers are ~aessary. (about 140,000 O.D. tons/year) It is ass& here that the flakes will be prepared by adjacent aperations "Ufacturing A nutber of suitable press sizes were to hardwood cants or possibly peeling veneer ad be msidered for ea& plant Output. the shaping lathe flakes are a by-product of these operations to be delivered by truck to Later, in the course of the study, it was the board plant. decided to include a wood supply situation consisting of 100%true flakes resulting from Figure 6 shows the forming and pressing a shaping lathe operation for the smallest flow sheet which is applicable to all plant output capacity plants. capacities and press amfigurations as only

432 ‘ &e size of unit is varied dependjng on For the sam reasons, in a southern lcca- pmss amfiguration and output capacity. tion any kind of structural flakeboard plant is unlikely to be supplied with sofbmcd raw Using these basic section flw sheets, a material. The farest resource in the south total plant flw sheet may be devised for all mists mainly of Southern pine and mixed mod supply amditions and at all plant outqut ha&mods. The pire tinher is likely to be capacities. Examples of these are shm in utilized for the manufa- of l-, ply- Figures 7, 8 and 9. wood and pulp. The chips generated by saw- mills and plyvJooa plants are also likely to be It was ass& that the waste genzraed by pur- by pulp mills at a prioe much in the plants (ba& fines and board trim) would ex~ssof the emanidly feasible limits of be used as the fuel for the dqers and the a structural flakeboard plant. scm of the boiler. About 50% to 60% of the fuel -?3=- softwood bgying and folEstrry waste (slash, inents are self-generated. The shortage in fuel. bran-, txps, etc.) may be available in chip requirerents is made up by purchased bark or form to flakebo& plants. The high bark hog fuel. Alternately, coal axld be used for content of this raw material will mder it making up the shorhge in the fuel demand of urdesirable for pulp manufacture - at least the boiler. The flow sheets related to the in the near term. In all probability, ways plant waste utilization as fuel in the dryers will be found to separate the bark frun the and the boiler an= alsoshawnin Figmxi 7, 8 wood in these types of chips and pulp mills and 9. will be foraed to utilize this softcllood raw material as well. Capital Costs In the long term therefore, structural Based on the plant design and flw sheets flakebard plants in the South will have to described abave, plant designs =re prepand fall back on the hardwood resource. mst of and equipmt msts, building 00s- and plant the unutilized hardwood in the South is of amstruction costs were estimated. the high aenSity species such as cak and hickory. Substantial munts of resear& work Table 1 shm the su“ry of capital msts will be required to prove the feasibility of at thvarious output capacities and press am- manufacturing a structural flak- of figurations. Each plant was designed for acceptable propertieS and density frcm this northern and southern locations, taking into high density raw material. “sideration @pent and building require- mts suited to northern and southern climtes. Table 2 shm the sacapital costs on a The manufacturing msts and earnings per unit of output basis for the purpose of projections for the various plants described cxxnparison. earlier and as surac\arized in Tables 1 and 2 have been analyzed and prepared by mans of a The Tables shw that the use of lathe ccmputer program developed for this special flakes results in considerable savings in purpose by the Forest Products Laboratory capital mts at all plant capacities against at Madison. !the projections are prepared for the use of tree length logs for the manufacture a great n- of potential plant locations of true flakes. Since lathe flakes arrive at and e available from the lab at Madison. the plant prepared, ready for drying, their use will also result in significant savings in It is understood that the ccarputer program processing and manufacturing axts. is available for analyzing and preparing data for any -ired plant location and raw mate- The availability of lathe flakes in ade- rial condition and is threfore suitable for quate quantities and in any given location may the accurate analysis of specific cases. This be questioned. It is also difficult to project paper proposes tm deal with the overall and or foresee the cost of such lathe flakes to a basic cxxpetitive position of structural flake- prcposed board plant or, in other wrds, the board against softwood plywood in the u.S. or price which may be acoeptable to a mufac- North Amrica in general. turer producing the lathe flakes as a by- product. At any rate, it was assumed that by In the final analysis, structural flake- providing a use for such a waste product of a board is mt to ccmplesnent the softwood hardwood lumber or furniture CQnPonent supply in the U.S. markets and, as a result, manufacbxer such operations would be en- will have to ccmpete with softmcd plywood. raged and rendered emnanical. The mufacture It is true that, potentially, structural of lathe flakes fmn softwoods was not con- flakeboard does have saw properties and sidered to be an eoonanical alternative since charactertistics which are superior to the saw material could also be turned into sheathing grade softwax3 plywood (surface pulp chips for which a pulp mill would normally properties, panel size, etc.) and could pay a nu& higher price than the board plant. therefoxe eventually find special ad specific

433 -et applications avoiding direct ompetition newly built plants. The fact of the matter is with the_ softklood plymcd product, sheathing huiever that newly built structural board ' grade or sanded eade. Still, initially as plants would have to axpete against plywoOa w11 as in the long run, structural flakeboard plants Wkicfi were built 5 to 10 years ago at a will have to carpete with the standard CDX substantially 1-r than present capital oost sheathing grade softvllood plywood in the am- and which are laryely depreciated. In reality wntional larye vlolune housing mnstruction therefore, the advantaw of plywood in total markets such as the roof decking, floor decking conversion oosts would be mre in the order of and wall sheathing applications. The oost $15 to $20 per Msf 3/8". This is a real and conrpetitive position of structural flakeboard significant advantage for plyw.m-3 in soft against UIX plywood is th&ore of vital markets as they are in a pition to lmr hportane in assessing the long term emdc prices without suffering actual cash losses. and financial viability of the flakeboard At the sane pricz level, nekl structural board industry in the U.S. and in North &erica. plants woad not be able to met their finan- cial charges such as interest and principal Table 3 shm a amprison of softwood paylnents on outstanding loans. plywood (CDX) vs. structural flakeboard mts. The oost figures sham in Table 1 are meant The wood msts of the two products are to represent the average range of mts smht difficult to experie~adby presently operating plymod plants against presently aperating waferbard Strandwood requires about .75 O.D. tons of plants. wood per Msf 3/8" output. Here, wood msts are easy to calculate. For instance, at $30 The costs of other types of structural per O.D. tm delivered log cost, the wood boards, such as oriented flakeboard plants or msts of a structural board plant muld be in flakeboard plants using raw materials other the order of $22 to $23 per Msf 3/8". In SOE than aspen roundmod, are likely to be in the instances, when using forestry drips in the same range as the ones sham in Table 3 under are of the board, the fines generation would structural board mts - scm spcial loca- be higher than in presently operating wafer- tions and mod supply ccxlditions excepted. board plants and therefore wood reqUiranents may be mre in the order of .8 to .85 O.D. The costs sham in Table 3 are roeant to be tons per Msf 3/8". The rejected fines hmever typical and to be used in a cmparative sense. may be used as fuel in the dxyers and in the They refer to plant cutput capacities ranging boiler and, at the presently applicable fuel fmabout 100 to 160 Wf 3/8" per annum. replamnt values, this would result in Wy do not include sane cost factors such as significant reduction in fuel purchase require- interest msts and Oorporate overhead msts mnts. sine these iterns are difficult to ampaxe as they vary fran plant to plant or corporation Tbe wood casts given for structural board to corporatian. in Table 3 represent the lw and the high range applicable under present circurnstanes. ?he amversion aosts of the two products Elost Canadian wafemplants pay about $32 are fairly similar except for chemical and to $35 per O.D. ton for aspen rwndwood. In labor msts. PlywaA has higher labor costs s~meinstanes such log msts are dmto $25 while structural board has higher Mcal per O.D. ton. It is unreasonable to e-ct oosts. Prior to 1974, these two factors were that wood in any form may be pur&& for reasonably balanced so that the total mnver less than $25 per O.D. trm delivered to the sion asts ere also about equal. The sharp plant. This figure therefore represents the increase in resin prices which toak place in law end of the range while the $35 per O.D. 1974 have hurt structural board a great deal ton figure would, at present, be representa- mre than plywood. As a result, structural tive of the high end of the wood cost range. board's cost disadvantage in chemicals is greater than the advantage in labor axits. On In the mufacture of plw, akuut 45% the whole and under present and foreseeable to 47% of the log ends up as veneer or even- future mditims, the direct amversion oosts tually as plywoOa. About 37% to 38%of the of structural board will be, on the average, wood v01u-1~is in the fonn of pulp chips or $7 e0 possibly $14 per Msf 3/8" higher than lumber manufactured from the axe. Assdmg those of CDX plymcxl. for the mntthat dl1 of this ends up in chips, these &ips are saleable at a reason- W IXJISL amversicm costs including able price to the pulp industry -- although depreciation (taken cm a 15 year, straight line saw pulp mills dislike veneer chips and basis) will also be about $12 to $15 higher for prefer sawmill &ips or chips made fran round- structural board than for plywood. wood. In the long run however, pulp mills will be forced to use this chip form so that It should be mted here that these cost chips generated by the plywood aperation do ocnparisons are for newly built plants against represent a substantial inaxe to the plywood

434 plant. The rest of the woo3 volm ends up in reality therefore, 7/16" wa€erbcard is sold shrinkage (in the Wing operation) and as against 3/8" plymcd at the sam price. In waste (dry trim). The latter may be used as the same application therefore (and at the fuel, at the present at a $20 to $25 per O.D. pEsent) waferboard costs would be an addi- ton fuel replamt value. ticmal $12 to $17 per Msf 3/8" higher than that of the thinner coapetitive axplywood For the purposes of (zu'pXing plyWOd costs producrt. with structural board costs, the wood 03Sts of plywood must be calcula&d on a net basis, that This oost disadvantage may be overam in is, log casts less chip sales. In the normal the future if oriented structural flake board plymod profit and loss statemnt, chip sales is proven to have similar strength properties are sham as in" and all wood 00s- are to plywood and is appmved by the codes thick- debited against plycod costs. lhis could be mss for thickness with the plywood product. hi-y misleading for purposes of canparison. The inpartanoe of achieving strength and therefore thickness parity with plywood in the The net wood aosts of plywooa therefore markets is thereby anply damnstrat&. will depend on actual delivered log cost to the mill, less the &ip price obtainable FOB There is haever another side of the cost plywoOa plant in any given location. These coin. structural flakeboards may be mu- figures may vary widely depending on the log factured in the eastern Wted States, close supply situation of a given mill as w11 as its to the large eastern markets and utilizing relative location to pulp mills or to a chip the mixed hamhod resource still plentiful in export loading facility. Furth-re, log t?eastern regions. In such locations, costs will also vary widely depending on structural board would enjoy the sam freight whether the mill is operating wholly or advantages relative to local markets and partially on self-awned tinker or on public, against plywood originating fmn the West Forest Serviae med tinher supply. Coast as presently enjqed by the southern plywoOa plants "facturing plywood from '&e wood cost range shm for plywood in Scuthern pine and selling the output in the Table 3 represents to the best of the author's South, Mihst and Northeast. hledge the net wood axts experienced by sheathing grade plywood industry at the At the present, about *thirds of the present. "he low range would represent a U.S. plymod supply originates in the West oondition wherein log costs are relatively lcw and about one-third in the South. This and am= ampled with relatively high chip supply situation may change sxwhat in the sales values. 'Ihe high range of $50 per Msf future in favor of the South. It is unlikely 3/8" wad be valid if log costs are relative- that plywood production in the South will ly high and chip sale values are on the lcw ex& the 8 Bsf 3/8" level or roughly 40% side. Sam plywmd plants may experienoe lmr of the present total U.S. demand for plywood. than the $30 per Msf net mod oosts while others may be in excess of the $50 per Msf 3/8" Against this supply picture, about 40% of range. As an industry average hwever, the the U.S. pl- supply is consum& in the net wood mst range sham in Table 3 is South, about 40% in the northcentral and believed to be fairly representative. northeastern regions and about 20% in theWest. It is therefore reasonable to expect that On the whole, the total cost ranges, southem plywood production will essentially representative of the structural board and be mnsmd in the South while structural plywood industries are fairly similar. The law board is likely to find its greatest success xange of both costs should apply to larger if manufactured 5n the northcentral and north- outplt plants (about 150 Wf 3/8") enjoying eastern regions, supplemnting and ccmpeting favorable wood supply corditions while the high with westem plywcod in the Midwest adNorth- range wuld apply to less favorable wood supply east mkets. In these locations (and if conditions at a laer plant output (about 100 properly located) structural board auld MMsf 3/8" pei annum). It is to be not& enjoy a $30 to $35 per Msf 3/8" freight hcwever that existing plywcod plants would advantage against western plywad which would still enjq a $5 to $10 per Msf 3/8" advantage largely overam the basic ad earlier demon- against newly built structural board plants due strakd cost disadvantages. For an oriented totheirlaer plant costs and resulting lcw structural board which wuld be acepted by depreciation charyes. the Codes on a thickness parity basis with plywood, the cost advantage against western At the present, structural board or plybod on a delivered axst basis to specific mnwrcially produced wafexboard has a further markets would be real and significant. disadvantage against plpccd. As nentioned earlier, waferboard is accepted in the housing In the southem location, a structural industry at greater thicknesses (1/16") in the flakeboard plant would have to ampte direc- load bearing application as plywood. In tly with southem plywcd in the southern

435 markets. This would appear to be a difficult would have a reasonably s-g cmpstitive. task and, unless southern &nand for plywoOa position against CDX ply"CX3 if located in the exdthe swly in the south, a relatively northcentral ard northeastern regicms of the high risk venture. For this xeascm and at united Stat32s. least in the initial stages of introducing structural flakebard to the Wets, the considering the diminishing supply of northcentral or northeastern lccatim mars softmod peeler 1- in the united sta*s to be mn= advantageous. The "facture of against the projected expansion of the markets structural board in the mth is likely to for plywood or plywood-like products, st=ruc entail a lesser degxee of financial risk after tural flakeboards present a good apportunity the product has been we11 established and to supplement this diminishing supply while accepted by the general housing mtruction utilizing a hithem unused fo-t resour~e. and possibly S~IE industrial markets. The eventual mufacture of strudmral "hem is a further interesting point which flakebard products for market wlicatims may be deduced from Table 3. Current prcposdLs other than those presently occupied by for the use of a structural flakeboard type softmod plymcd is a good, long range panel include its application as core material possibility. in a oonpositicm type panel having "er faoes and a structural board are. The product The dewlopent of lmer oost and more is nand "Can-ply", or "plystran'a as manufa- effective resins and resin extenders is also tured by Potlatch at Lewiston. In this a gocd possibility. This would further product, the structural board sirrply replaces strengthen the qtitivepositicm of core veneer in a plymcd-like panel. It is of structural flakeboards against plywood interest to ccmpare the aost of manufacturing products. structural board against veneer manufacturing msts.

Table 3 shms that the approximate average mt of manufacturing structural flakeboard is in the order c,f $90 per Msf 3/8" or $30 per Msf Y8". This is fairly close to the approxi- mate price range of fir core veneer an a 1/8" basis as guoted an the wst Coast. The actual ast of a veneer, and especially axe veneer, to plywood manufacturers is prdMbly swt less. On this basis; the substitution of vemer with structural flakeboard does not seem to offer significant advantages. A substantid tightening of the oore veneer supply both in the West and in the South and a consequent increase in the cost and price of veneer will have to take place before such substitution may be wnsidered eoonanical. Conclusions

Fmn the foregoing analyses, we may mnclude the follcrwing. WafeKbOard, the only strueal grade flakeboard product carmercially manufactued at the present, has found a strong acceptance in both the Canadian and U.S. markets. At present price levels, these plants are gmeratixq attractive earnings, in spite of the fact that waf-ard must be sold 1/16" thicker than plywad in the same load bearing application.

The results of the "ently ongoing researdl work indicae that oriented structural flakeboard aould easily adtieve strength parity with plywood and aould be sold th~cknessfor thickness against plywcod in the amstruction markets. Plants manufacturing sudl a product

436 c TABLE 1

U.S.O.A. Forest Products Laboratory Wadi son , Wisconsin STRUCTURAL PARTI CLEBOARO SIIFWIRY OF CAPITAL COSTS WAC1TY/Y R 40% LATHE FLAKES- 40% TREE LENGTH LOGS- MMsf 3/8" LOCATION PRESS SIZE 100% LATHE FLAKES 60% CHIPS 60% CHIPS

50 SOUTH Continuous f 7,100.000 f 8.200.000 f 9,950,000 4'~8'-24 opg $ 7,100.000 f 8,200,000 f 9,900,000 4'~16'-12 opg $ 8.100,OOO f 9.200,OOO f 10.800.000

50 NORTH Continuous f 7,450,000 f 8,550,000 f 10.400.000 4'~8'-24 opg f 7.560,000 f 8.670.000 f 10,500,000 4'~16'-12 opg f 8.550.000 f 9.600.000 f 11,600,000

100 SOUTH 4'~16'-24 opg f 11,700.000 f 13,550,000 NORTH 4'~16'-24opg f 12,300.000 f 14.600.000

150 U)mH 4'~24'-24OQg f 14.900,OOO f 17,000.000 8'~24'-12 ow f 17,000.000 f 19.200.000

150 NORTH 4Ix24l-24 opg f 15,800,000 f 18,700,000 8'~24'-12 opg f 18.000,OOO f 21.000.000

~~ 200 SOUTH 8'~24'-16 opg f 20,000,000 f 22,400.000 NORTH 8'~24'-16 opg f 21.500.000 f 24.500.000 .....

TABLE 2

U.S.O.A. Forest Products Laboratory kdison. Wisconsin STRUCTURAL PARTICLEBOARD

SUMMARY OF CAPITAL COSTS PER UNIT OF OUTPUT ($ PER Msf 3/8") CAPAC ITY/Y R 40% LATHE FLAKES 40% TREE LENGTH LOGS msf 3/8 LOCATION PRESS SIZE 100% LATHE FLAKES 60% CHIPS 60% CHIPS

50 SOUTH Continuous $142 -00 $164.00 5199.00 4'~8'-24 opg 142 .OO 164.00 -198.60 4'~16'-12 opg 162.00 184.00 216.00

50 NORTH Continuous 149.00 171.00 208.00 4'~8'-24 Opg 151.00 173.00 210.00 4'~16'-12 opg 170.00 192.00 232.00

100 SOUTH 4'~16'-24 Opg 117.00 135.00 100 NORTH 4'~16'-24 opg 123.00 146 .OO

150 SOUTH 4'~24'-24 opg 99.00 113.00 8'~24'-12 opg 113.00 128.00

150 NORTH 4'~24'-24 opg 105.00 124.00 8'~24'-12 opg 120.00 140.00

200 SOUTH 8'~24'-16 opg 100.00 112.00 200 NORTH 8'~24'-16opg 107.00 122.00

437 TABLE 3

COMPARISON OF PLYWOOD(CDX) vs. STRUCTURAL BOARD COSTS

PLVWWD STRUCTURAL BOARD

$/MSF 3/0"

CHEMICALS 8.00 - 10.00 25.00 - 28.00 POWER 3.00 - 5.00 4.00 - 7.00 STEAM 8 FUEL 1.00 - 3.00 1-00 - 3.00 LABOR 18.00 - 24.00 12.00 - 15.00 SUPPLIES 5.00 - 7.00 6.00 - 8.00 ADMIN~STRAT~VE SALARIES 8 EXPENSES 4.00 - 5.m 4.00 - 5.00 TAXES 8 INSURANCE 2.00 - 3.00 3.00 - 4.00 DIRECT CONVERSION COSTS 41.00 - 57.00 55.00 - 70.00 DEPRECIATION (15 YEAR STRAIGHT LINE) 9.00 - 11.00 10.00 - 13.00 TOTAL CONVERSION COSTS 50.00 - 68.00 65.00 - 83.00

WOOD COSTS LESS CHIP SALES 30.00 - 50.00 a S25/O.D. TON 19.00 a t35/O.D. TON 28.00 Fig. 2 -- Basic section flwsheet. wood yard TOTAL COSTS 80.00 - 118.00 84.00 - 111.00 and flaking section. Type WF-2. Tree length log flaking.

TCUCC DUMP ii 1

I--- I---I---I I DRY E. 9, M ETECI NG- --

TO DCY_E--

Fig. 1 -- &sic section flmhet. wood yard Fig. 3 -- Basic section flm sheet. wood and flaking section. Type WF 1 and WF la. yard and flaking section. Type WF 3. &p Lathe flake handling. handling flaking.

438 IFACE 1

4CAL€ -1 , P-.SCALE.

Fig. 4 -- Basic section flmheet. Drying and blending section. Typ DB-1.

Fig. 5 -- Basic section flaisheet. Drying and blending section. ?Lpe DB-2.

439 ?*" : L- 1-.--'I='-

I

i

Pig. 7 -- Basic plant flow sheet. Plant output capacity: 50 M.M.S.F., 3/8" per yea. kbd i.nput conditions: 100 % shaping late flakes. . .*

.-

1 TYPE DO-Z

c

Fig. 8 -- Basic plant flm sheet. Plant output capacity: 100 M.M.S.F. 3/8" per yc.,rr- Wad input mnditions: 40% lathe flakes and 60 % chips.

441 ADHESIVES FROM SOUTHERN PINE BARK- A REVLE?; GP PAST AND CURRENT APPROACHES TO RESIN FomuL~,no;,PROBLEMS

Richard W. Hemingway Principal Wood Scientist Southen? Fovest Experiment Stat.ion u. S. Forest Service Pineville, Louisiana

Abstract adhesives under industrial conditions. In this paper, some of the proper2- Basic properties of conifer bark ties of conifer bark polyflavonoids polyflavonoids and various approaches and various approaches to their use to their use in wood adhesives are in wood adhesives are reviewed. The reviewed. The object is to focus on intent is to focus on some of the the important problems which must be important properties and problems overcome if these abundant and renewa- which must be dealt with if these a- ble phenols are to be utilized i!?wood bundant and renewable phenols are t(; adhe si vc formulat ions. be utilized in wood adhesives.

--_Introduction ----__ Polvflavonoids-- Along with the urgent necessity __-St ruct ____ we -f shifting from petroleum to alter- nate sources of energy, it is also The materials in conifer barks essential to develop new sources of which are the active constituents used industrial chemicals from renewable in adhesive formulation are polymers resources. Oil supplies can be built up of flavonoid units. These expected to be increasingly diverted polymers are classified on the basis from energy to the production of petro- of their solubility into groups such chemicals, but there is no assurance as the condensed tannins (soluble in of the long term supply of the usual alcohol and water), the phlobaphenes array of inexpensive base chemicals, (soluble in alcohol but not water), Despite debate over its timing, the and the phenolic acids (insoluble in relative cost of chemicals derived neutral solvents but soluble in from oil must eventually climb dis- alkaline solutions) (1). When proportionately to the increase in attempting to use these polymers In cost of renewable resources such as wood adhesive formulations, it is forest products, important to have developed a Of particular concern tc the for- realistic conceptual model of their est product,^ industry is the long term structure to assist in making decis- supply and cost of chemicals for the ions as to how to accentuate or synthesis of adhesives which will be minimize properties of these polymers. required in inereasin@ amcunts a5 Despite the efforts of many noted materials such as exterior flakeboards chemists, the structure and properties are made from forest resources of of polyflavonoids from conifer barks diminishing quality. For the past 25 remain poorly understood. years, particularly in petroleum Considerable progress has been deficient countries, a concerted made, however, on the chemistry of the effort has been made to replace sub- proanthocyanidins (dimeric and staiitial amounts of phenol and resor- trimeric flavonoids) by the research cinol with tree barks or their extracts groups of Roux (2), Haslam (3), and for the preparation of wood adhesives, Weinges (4). Recent work by Haslam A resurgenne of interest in this et al. (5) suggests that the procyan- possibility has also occurred in the idins (Droanthocyanidins which give United States because of the changed c:qayii din chloride on treatment with ecoJiomic climate relative to petroleum. HC1) arc forined from a flavene However, despite considerable research interntrdiate (T) hhich is held and development, with the exception of by an enzyme to permit stereospecific the use of wattle tannins in limited formation of either a carbocation (T!) amourits , these adhesives have not been or a flavafi-3-01 (JlI) and that the widely applied by industry. The lack procvanidins are then formed noti- of thteir. acceptance has been the enzymatically by condensatiori of' tkll result 01' both a relatively low cost of carboration (C-11) with the nucleo- ~IICJ!C1 ~JIthe past and technoiogical phillic sites (C-8 nr C-6) of tlie pr.ob1 ems encountered when using these flavan- i-(11s , Cqiit itiued concleri:,nt, ioi