CPCUNDIVOOD AND CHIP GROUNDWOOD

Transcription

1 IULTURE RM d_ta) erl-17 PUNDIVD AND HIP GRUNDWD PIAPIN AND PAPERMAIING EXPERIMENTS N PNDERSA PINE Revised September 1959 No UNITED STATES ḊEPARTMENT F AGRIULTURE FREST PRDUTS LABRATRY FREST SERVIE MADISN 5, WISNSIN In oopertion with the University of Wisconsin

2 GRUNDWD AND HIP GRUNDWD PULPING AND PAPERMAKING EXPERIMENTS N PNDERSA PINE By E. R. SHAFER, hemicl Engineer nd AXEL HYTTINEN, hemicl Engineer Forest Products Lbortory, 1 Forest Service U.S. Deprtment of Agriculture Summry Groundwood pulps prepred from ponderos pine thinnings nd top ends of swtimber trunks were shown to be equl in strength nd higher in brightness thn the verge of number of commercil newsprint-grde groundwood pulps. hip groundwood mde by disk milling wter-sturted chips hd bout the sme bursting nd tensile strength s ordinry groundwood pulp of the sme freeness, but it hd higher tering resistence nd lrger proportions of the longer fibered frctions. Pper mking experiments indicted tht good-qulity bookstock, newsprint, toweling, so-clled "construction" ppers used in rt clsses, nd pulpbord cn be mde with ponderos pine groundwood nd chip groundwood pulps in their furnishes. Introduction This report presents the results of groundwood pulping experiments on ponderos pine ( Pinus ponderos) thinnings nd top ends of the merchntble boles of the swtimber. hip groundwood pulping experiments were lso mde from the tops of the boles. The pulps were used to mke book, news - print, toweling, nd construction ppers nd pulpbord. _Mintined t Mdison, Wis., in coopertion with the University of Wisconsin. Report No ( Revised)

3 Description of the Wood The thinnings were cut from 45-yer-old forest in Bonner ounty, Idho. The pulpwood smple consisted of 24 sections, 8 feet in length, tht hd been cut from 9 trees. The trees rnged from bout 5 to 1 inches in dimeter brest height, nd from 35 to 5 feet in height. Six of the nine trees were of the codominte clss, with the reminder being suppressed. The 4-foot top ends of swtimber boles were obtined from logging opertion in southwestern Idho stnd 25 to 3 yers old. The verge vlues for certin physicl tests mde on these smples were: Item Thin- Top nings ends Dimeter inches Annul rings Rte of growth rings per inches Dimeter of hertwood inches. 5 Hertwood, by volume percent. 9 Brk, by volume do Brk, by weight (moisture-free bsis) do Summerwood, by volume do '19.7 Density (moisture-free weight nd green volume) pounds per cubic foot Groundwood Pulping Thinnings Three groundwood pulping experiments were mde on the thinnings to produce pulps hving firly wide rnge of properties. The dt on grinding nd pulp properties re given in tble 1. The pulps from grinder runs Nos. 963 nd 967 were of freeness used for printing ppers. In strength they were comprble to pulps mde from southern pine, somewht lower thn spruce, nd equl to overll verge for 29 commercil newsprint-grde pulps tested t the Lbortory. Though the two pulps hd similr properties, they were mde under considerbly different conditions of grinding. Grinder run No. 963 ws mde t low Report No (Revised) -2-

4 grinding pressure with firly shrp stone surfce, wheres grinder run No. 967 ws mde t much higher grinding pressure with dull stone surfce. The results of the two runs illustrte firly generl principle of groundwood pulping, tht the best strength of pulp is obtined t the lest energy consumption per ton by using high pressure nd dull stone. Fctors limiting the use of this desirble combintion of conditions re the mount of power vilble (the power input is generlly high in such circumstnces) nd the inbility to set nd mintin stones constntly t one grinding-surfce condition. The pulp from grinder run No. 962 ws corser nd hd lower strength thn the other two; lso, it hd higher freeness thn groundwood pulps ordinrily used for printing ppers. Groundwood pulps of good color cn be expected from young ponderos pine of this type becuse of the very smll mount of hertwood present. Top Ends Two grdes of groundwood pulp were mde from the top ends--one with low freeness for use in mking newsprint, book, nd toweling ppers, nd one with higher freeness for mking construction pper nd pulpbord. The dt for these pulps re given in tble 2. The groundwood pulps were of good qulity with strengths equl to, or better thn, those of the commercil groundwoods given in the tble for reference. The book-grde pulp (grinder run No. 113) ws drker in color thn the reference commercil pulp, so it ws brightened by bleching tretment using 3 percent of 5 percent solution of hydrogen peroxide. The brightness increse ws percent. The groundwood mde for the newsprint (grinder run No. 1141) hd stisfctory color for tht purpose. Its freeness ws comprble to tht of southern pine pulp mde for newsprint mnufcture. The bord grde of groundwood (grinder run No. 1139) hd good strength nd color for pulp of tht grde nd ws mde with resonble consumption of energy. hip Groundwood Pulping Wheres groundwood pulp is mde by pressing sticks of debrked pulpwood ginst revolving grindstone in conventionl pulpwood grinder, chip groundwood pulp is mde by grinding chips in mill, such s disk mill. Although mking groundwood from chips is reltively new, the process ppers to hve considerble promise for utilizing chippble softwood swmill residues tht re too smll for grinding in the ordinry pulpwood grinder. Report No (Revised) -3-

5 The chip groundwood pulps were mde from the sme shipment of ponderos pine top mteril tht ws used for mking the groundwood. The sticks of wood were converted to chips of the stndrd size used for chemicl pulping. The chips were sturted with wter nd ground in double-revolving disk mill t n industril lbortory. The pulps were sent to the Forest Products Lbortory for the ppermking experiments. Two grdes of chip groundwood were mde by milling t two levels of energy comsumption. ne mde t 8 horsepower-dys per ton hd the lower freeness nd ws designted for use in book, news, nd toweling ppers. The other, mde t 63 horsepower-dys per ton, hd higher freeness nd ws designted for use in the bord furnishes. A third pulp ws mde from pine chips tht hd been impregnted with hot neutrl sodium sulfite solution before milling. This pulp ws used in one of the newsprint runs. The three chip-groundwood pulps were pssed through centrifugl cleners for removl of shives before being tested nd used in the ppermking experiments. The experimentl dt for the pulps re given in tble 2. A comprison of pulps of bout the sme freeness disclosed tht chip groundwood No. A-25 ws produced with considerbly higher energy consumption thn groundwood pulp No The bursting nd tensile strength vlues were slightly higher for the groundwood, but tering resistnce ws pprecibly higher for the chip groundwood. The greter mount of longer fibered mteril retined on the 28-mesh screen probbly contributed to the higher tering resistnce of the chip pulps. The better tering vlue of the chip groundwood my be considered s desirble ttribute. rdinry groundwood is generlly lcking in this property. hip pulp No. A-27, produced from the chips treted with hot sodium sulfite, ws high in freeness, hd modertely good bursting nd tensile strength, nd hd very high tering resistnce in comprison with the groundwood pulps. An improvement in the bursting nd tensile strength without excessive losses in freeness nd tering resistnce could undoubtedly be obtined by beting this pulp. Ppers Mde From Groundwood Pulps Produced From Thinnings Ppermking runs were mde on the Lbortory Fourdrinier pper mchine, which produces pper 12 inches wide. Report No (Revised) -4-

6 Book Pper In mchine run No. 385 (tble 3) book pper ws mde from mixture contining 6 percent of ponderos pine thinnings groundwood (grinder run No. 963) nd 4 percent of commercil bleched western hemlock sulfite. For comprison, dt re given for pper mde in mchine run No from the sme sulfite pulp nd 6 percent of commercil bleched groundwood pulp. The ponderos pine pper ws higher in bursting nd folding strength but lower in tering nd tensile strength thn the reference sheet, nd it ws higher in density nd somewht lower in opcity. The high density probbly ccounts for the higher resistnce to cstor-oil penetrtion, s well s for the greter resistnce to ir flow through the sheet s indicted by the porosity test. Some, nd perhps ll, of these properties cn be corrected by the ddition of cly, usul constituent of groundwood book pper, nd by djustments in pper-mchine opertion. There is nothing to indicte tht stndrd book grde of pper cnnot be mde by using ponderos pine groundwood for the groundwood component. Newsprint Pper Newsprint ppers were mde in mchine runs Nos. 384 nd 3867 (tble 3) by using 8 percent of the ponderos pine thinnings groundwood pulps nd 2 percent of commercil unbleched spruce sulfite pulp. The principl difference between the two trils ws in the groundwood used. In mchine run No. 384, 6 percent of the groundwood component consisted of pulp from grinder run No. 962 nd 4 percent from grinder run No The freeness of this mixture ws 19 milliliters. The strength of the pper ws lower thn desirble in comprison with commercil newsprint ppers. The second tril, mchine run No. 3867, ws mde by using the sme proportions of sulfite nd groundwood, but this time, the groundwood pulps were blended in proportions to give lower freeness (bout 12 milliliters). The groundwood mixture consisted 7 percent of pulp from grinder run No. 967 nd 3 percent of pulp from grinder run No The strength of the pper in the second tril ws improved over tht in the previous tril, nd it ws equl in ter nd tensile strength to the verge of number of commercil newsprint ppers. The bursting strength ws bout 2 percent lower thn the verge, but within the rnge of this property for commercil newsprint. The brightness of the ponderos pine newsprint ppers ws very. good. Report No (Revised) -5-

7 Ppers Mde From Groundwood nd hip Groundwood Pulps Produced from Top Mteril Western hemlock bleched sulfite pulp or southern pine bleched sulfte pulp ws used s the chemicl pulp portion in the ppers nd pperbords mde from groundwood nd chip groundwood pulps of ponderos pine swtimber tops. The chemicl pulps were processed in beter nd then the groundwood or chip groundwood pulps were dded to the furnish. The qulity of the experimentl ppers ws judged by compring them with reference ppers mde on the mchine from severl commercil groundwood pulps (see tble 2 for their properties) nd the commercil chemicl pulps. Newsprint The sulfte pulp ws beten to freeness of 475 milliliters, ndin Stndrd, for these runs. For the reference run (mchine run No. 489, tble 4) the commercil news-grde spruce-spen groundwood (shipment No. 4313) ws used. When the experimentl ponderos pine pulps were substituted for the commercil groundwood (mchine runs Nos. 481 nd 4812), ppers with strength properties equl to, or better thn, the reference sheet were produced. It ws necessry to jordn the furnish contining the chip groundwood to reduce its hedbox freeness to vlue pproximting tht of the reference run. The pper contining chip groundwood hd n opcity vlue comprble to tht of the reference pper, but the pper contining the ponderos pine groundwood ws somewht lower in this property. The chip groundwood mde with neutrl sulfite-treted chips ws substituted for prt of the untreted chip groundwood nd prt of the chemicl pulp in mchine run No This pper, which contined only 1 percent of chemicl pulp, ws comprble in nerly ll respects to the reference run. All of the experimentl ppers, including the reference run, were lower in opcity thn the verge for number of commercil newsprint ppers. Book oting-bse Pper Bleched ponderos pine pulps were used in the furnishes of book cotingbse pper. A reference run (mchine run No. 4822, tble 4) ws mde using the commercil spruce-spen book-grde groundwood followed by Report No (Revised) -6-

8 runs (mchine runs Nos nd 4826) in which the ponderos pine pulps were substituted for the commercil groundwood. The pper contining either the ponderos pine groundwood or the chip groundwood ws equl or higher in strength thn the reference pper. They were lso slightly brighter, but lower in opcity. All of the ppers contined 7 percent of cly filler. The opcity possibly would hve been improved by using more filler. The pper contining the chip groundwood ws little stronger thn the one contining the pine groundwood. reped Toweling Toweling pper cn vry considerbly in properties nd pulp composition. For these tests, furnish contining 5 percent of commercil news-grde groundwood nd 5 percent of southern pine semibleched sulfte pulp (mchine run No. 4827, tble 5) ws used s bsis of comprison. The sulfte pulp used in ll runs ws beten to 55-milliliters freeness. To ech furnish, 1.5 percent of wet strength resin (bsed on weight of totl fiber) ws dded. The creping ws done on the first press, nd the second nd third presses were bypssed. The ponderos pine groundwood used ws mixture of the intermedite nd high-freeness pulps (grinder runs Nos nd 1141, tble 2). The chip groundwood used ws the low freeness pulp No. A-25. The ppers contining the pine groundwood (mchine run No. 4828) nd chip groundwood (mchine run No. 4829) pulps were firly good in dry strength properties compred to the reference run. Both were more bsorbent of wter thn the reference, the one contining the chip groundwood pulp being especilly bsorbent. The pper contining the pine groundwood ws firly good in wet tensile strength, but the one contining the chip groundwood ws pprecibly lower thn the stndrd. onstruction Pper onstruction pper, which is high in groundwood content, is used for rt work in schools. The usul bsis weights rnge from 4 to 8 pounds per 3, squre feet. The construction ppers mde in these experiments were close to the 8-pound weight. A groundwood content of 8 percent ws used. The control run (mchine run No. 485, tble 5) ws mde with commercil bord grde of spen groundwood pulp nd southern pine bleched sulfte pulp tht hd been processed to freeness of 5 milliliters. The ppers mde with ponderos pine groundwood nd chip groundwood substituted for the commercil groundwood were better thn the reference run Report No (Revised) -7-

9 in ll strength properties. The pper contining the conventionl groundwood ws better in bursting nd tering strength thn tht contining the chip groundwood, though the strength of the ltter pper ws dequte. Pulpbord Groundwood comprises the mjor portion of the fiber furnish in such bords s bottle cp, mtchbord, nd shoebord, s well s number of other specilty bords. The requirements nd properties of these bords vry considerbly depending on the end use. Mediumweight bord weighing pproximtely 6 pounds per 1, squre feet nd contining 7 percent of groundwood ws selected s the bsis for compring the experimentl groundwood pulps. The pulps used in these runs were the sme s those used to mke the construction ppers. The bords contining the pine pulps were better in most properties thn the control run. The bord contining the chip groundwood hd very good tering strength nd folding endurnce. In other properties, it ws not quite so good s the bord contining the ordinry pine groundwood. The dt re in tble 5. Report No (Revised)

10 Tble 1.--The groundwood pulping of ponderos pine thinnings Grinder run No. : 962: 963: 967 Grinding conditions:1 Pressure of wood on stone lb. per sq. in.: 2: 15: 35 Power input? hp: 65: 45: 1, 3 Grinding rte?' 3 Energy consumption tons per 24 hr.: 1.5:.7: 1.76 hp.-dys per ton: 44: 64: 57 Pulp properties- 4 - Bursts pts. per lb. per rem:.14:.23:.26 Ters gm. per lb. per rem Tensile :. lb. per sq. in.: 765:1,43:1,616 Breking length meters:1,67:2,55:2,76 Density gm. per cc:.33:.4:.41 Brightness.. percent: 6.4: 68.: Freeness: (ndin Stndrd) ml.: 255: 95: 55 Screen nlysis (Appleton selective screen): : : : Retined on 24-mesh percent: 2.1: 2. Retined between 24- nd 42-mesh percent: 5.8: 5.2:... Retined between 42- nd 8-mesh percent: 41.7: 4.7 Retined between 8- nd 15-mesh percent: 14.4: 8.1 Pssing 15-mesh percent: 36.: 44. lln grinder runs Nos. 962 nd 963, 6-grit rtificil stone with mediumshrp surfce ws used; in grinder run No. 967, the pulp stone ws 9-grit rtificil stone with dull surfce. In ll experiments the peripherl speed of the stone ws 3,12 feet per minute, the grinder-pit temperture rnged from 13 to 15 F., nd the grinder-pit consistency rnged between 3 nd 4 percent. Per squre foot of wood- to stone contct surfce. /Bsed on moisture-free wood. gulp through flt plte screen hving slots.8 inch in width. Rem size 25 x 4 inches, 5 sheets. hower brightness due to molds tht developed on the wood smple when stored in covered continers. Report No (Revised)

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