Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~lS1~314
The problem of pitch control in papermaking has previously been
recognized. The pitch in the fibers of wood pulps is associated with naturally
occurring lignin dispersing agents. Cooking and mechanical agitation which
occur during the pulping by the sulfite process liberates pitch and these
natural dispersing agents. But, as a result of the mechanical work on the fibers,
the natural dispersing agents liberated along with the pitch are inadequate to
keep the pitch from depositing on the equipment employed in beating, hydrating,
re:fining, bleaching, and even on the wire used for forming the sheet. Because
of the tendency o-f the pitch to agglomerate within the pulp suspension or
cleposit on the surfaces of the wire or other equipment and then to break free
in the form of part:iclos of considerable si~e, the pitch frequontly causes the
formation of spots or holes in the sheet formed or may adhere to the wire or
press rolls or drier rolls ancl cause toaring of the sheet. This results in
occasional tearing of the sheet dur;ng -formation or in the production o-f sheets
with numerous imperEectiolls. Among other consequences involvecl are thc e~pc?nse
of cloanillg the I~ chinory Erequently cither with solvcnts or stcam, an(l thc loss
O ~ prOdUCtiOII dUr:illg c 1 c;lll i llg ;IllCI dll r i llg r Cn l ;l (` i ng Ol)Cr;l t i OIl !; CIlUSc?Cl by hre:lkdown
o-E the shoet.
:rn the art:.ic1c cl~titlc~ l'ar~:iclc (,onccntl.ltiol~ n In~l~ort;lnt
I'aralneter in l'itcll l~oblcllls," I-y 1,.11. /~1 Ic~ll, wllicll apl~c.lrs in ~:he Iralls;lctio!l.s
oE the Iechllical_~e~tioll ol` ~:llc (all;l-li;lll I'ull) and l'al)cl ~sso~i;ltioll ~or .]UIIC,
1977, :it is clolllollstl<l-tcd -LIl;lt thos~ woo(l pllll)s wllich C;lllSC l-itcll problellns contilir
a hi~h concclltr.ltioll oE sllspclldcd col loid.ll l~i-tcll p;lrticle.s~ 'I'hc pitcll cleposit
potcllti.ll of a pllll~ is shown to hc pl~oportioll.ll to thc concentration o-E collo-idal
pitCII drol~lets.
I`his article shows tha-t it is possible to measure the pitch by micro-
scopic obscrv.ltion the concentration of colloidally suspended pitch droplets in
*~
~S~9~4
a blood eounting chamber known as a hemacytometer. This particular method is
described by the author in this article as follows:
"A. Particle ~oncen~ration Determinations
Each pulp sample is filtered through a rapid,
coarse, filter paper ~Reeve Angel No. 202) to remove
the fibres, and the concentration of colloidally sus-
pended pitch droplets in the filtrate is counted in a
hemacytometer with a microscope. . ."
It is known that certain water-soluble polymers are capable of acting
as pitch dispersants whereby the pitch can be maintained in a colloidal state of
subdivision without agglomeration of the particles occurring. It is further
known that certain polytners and, in particular, low molecular weight water-
soluble cationic polymers, will cause the pitch particles to become attached to
the fibers. This removes the colloidal pitch particles Erom the whitew,lter and
tends to prevent deposit formation from occurring.
The ~present invent;oll ;s pred~ic;lted ut)on the discovery of certia;ll
cat;onie pulylllers whicll give superior collo;dill pitcl~ll;lrticle recluctioll ;n
aqueous pulps.
~ IUS thi.s illv(i~llt:ioll pl'OVi(lCs .1 IllCthO(I oE l`CdUCillg the alllount Or col-
]okl;ll pitcll l)atticles in a(lllC011S p~ )'; which COIIII)risCs I t'C;ltillg Sai.(l pllll)S with
a watel~-d-ispersil)le polyqlt;l~erllary polylller ol essenti:llly line~lt structure Ct)ll-
sisting ossellti;llly of tl~e d.ilullct.i.oll.ll rcact:ion prodllct of a lowcr dialky1<1.lll:i.tlc
and a diEullctioll;ll epoxy coml)olllld sclcctcd from the grolll) consisting of ep-ihalo-
hydrills, d;opoxides, percursors of epih;llollydrins and diepoxides which under
alkaline conditions are readily converted into the corresponding epoxy conlpounds,
and m;xtures thereof, said polyquaternary polymer containing repeating units of
~L~5~914
N - E ~
L 12 ¦.X
wherein R and R2 are individually selected from the group consisting of alkyl
of 1 to 3 carbon atoms, and E is a residue obtained from said epoxy compound;
the total amounts of reactants being substantially equimolar, the combination
of which is such as to provide a polyquaternary compound l~hich as a 37% aqueous
solution, by weight, based on the cationic portion of said polyquaternary
compound has a viscosity at 25C. o:f at least 100 centistokes; and X re-
prescnts an ion :forming thc anion;c portion of said polyquaterllary.
~ pre:ferred speci.es o-f polymers of tllc type dcscribed above are
thosc prepared by us:ing as thc rcactants epichlorollydrill and d:imetllylamine.
Polyquaterllary polymcrs of the typc described .~hove alld thcir metllod
of preparation are dcscribed in lJnited Statcs 3,738,9~l5.
rl`he dosage Or acti.vc polymcri.c comllollcllt llSCd t(l trc;lt thc ;Iqllcous
~u:ll)s may -range :from as li.ttlc ;m~ ().l ul~ to ;IS mllcll ;IS I killogr;llll l)cr ton o~F
ulp bascd on dry fibc:r wc:i.gllt.
rO :il:lustr;ltc thc clfi(:lcy ol`l~ly illvcntioll, thc lollowillg is l~rc-
SCI~tc~(l I)y w:ly ol CX;IIIII)`l C.
Tllc tcst mctlloll uscd corrcsl)(!lldc(l gcllcr;llly to th;lt dcsclibcd l~y
2() L,.ll. Allcll ;n h;.s ;Irt:iclc, "I'i.tclll';lrticlc (onccllt:rltioll: an Iml~ortallt
P:lr;lllleter in l)itch rroblellls~ wll:icll al~l)c~lrs in thc l`ransactions of thc Icchlli.-
cal Sect;.on of the Calladiall Pulp ;IIld l'apcr Association for J~me, 1977.
IJsillg th:is test metllod, polymers of the invcntion were screened on
a variety of pulps. The results are reported in terms of pitch particles per
milliliter. In other cases it is reported in percent of pitch particles fixed
-- 3 --
~5~)914
onto fibers by the polymers. This result is determined by the following equation:
rNumber of pitch Number of pitch
¦particles/mL - particles/mL - ~% pitcl~ particles
untreated sample treated sample X l00= fixed onto fibres
~Number of pitch particles/l by polymer
~mL - untreated sample ~¦
The following procedures leading to the predictability of percent
efflciency for the various polymers tested in regards to pitcl- control were used
to generate all of the results in the following tablcs:
l. 1ake representat:ivc white watcr samples throughout the system as
far back as the grinder showers in thc ground-wood mill but at a point in thc
system prior to pitch deposits appec1ring and presenting a problem.
2. I'lace a known aliquot of thcse white water salllples ;n a Britt
l)ynamic Jar or BDJ. Set the spce(1 varial)lc of the stirrcr for tllC Britt .Jar in
a rangc of 500-l000 rpm for 2 minutc.s ;Ind dr1w off a sm.lll (lu;llltity oE the wh;tc
w~ter prior to the polylller additioll. Ihi~s would l)c collsidcrc(l;l I)llnk or a
control count al)sellt tre;ltlllcl-t cllcllli~;lls.
3. Add ;l knowll doslgc ol poly1llcr lo ~llc ;lli(lllot ol whitc w;ltcr still
cont;lilled in the l31)), sct tllc sl)ccd v;lri;ll)lc ol lllc stirlcr ;It t.l-c .s;lmc sl)cc~d
use(l ft)r the control w;tllllo trc;l~lllcllt, ;IIId ;l~ tC it for 5 mill~ltcs ;It this
spccd .
4. 1hc l`iltrltc .sholll(l imlllc(liltcly bc w;thdr;lwll. If thc pitcll plr-
ticle concelltr;ltioll COllllt i~s c.Ytrcnlcly higll, ;l dilut-ioll E.lctor can bc int-roduced.
IE this dil~ltion step is nOt neccss;1ry, thcll ;I known aliq1lot of this filtrcltc
is l)laccd 011 the hel~ cytollleter. The helll.lcytollleter is placed under the micro-
scope and colloidal pitC]l particlcs are counted. Thus a count can be completed
in a knol~l volume of liquid over a small square in the American optical hema-
-- 'I --
~L~5~4
cytometer. The measurement of this volume in the hemacytometer is 2-5.10 7cm
and the particle concentration would be expressed as the number times 106cm3.
5. The initial count of the white water prior to the addition of the
polymer is considered the blank. The second count is obtained using the known
dosage of polymer addition. This second count would be subtracted from the
blank and thus, a percentage efficiency of the polymer can be calculated using
the previously mentioned formula.
The results of these tests are set forth in Tables I - VII.
TABLE I - GROUNDWOOD
Polymer Pitch Particules
/mL
. .
Control 107,500
Competitive product A 52,250
Polymer of Invention 48,750
TABLE II - GROUNDWOOD
Polymer Pitch Particules
/mL __
Control 58,750
Polymer of Lnvention 36,250
Competitive prodtlct A 72,500
Competitlve produc~ B l46,250
Competitive prodnct ~ Ls belLeve(l to be .In acrylallll(k~-dlllle~llyl-amLno ethyl
methacrylate dimethyls~llE<Ite qu.llterll.lry copolymer in about 74:26 by we:L~ht;
competitive product B is a nitric acLd solution o~ poLy(2-bydroxy propyl amino
ethyl acrylate).
A terpolymer of epichlorohydrin, dimethylamine, and ammonia in a mole ratio of
1:0-85:0.15 prepared according to US 3,738,945 having an approximate molecular
weight of 50,000, used as a 47% by weight aqueous solution. This polymer is
commercially available. -5-
r~
115~914
TABLE III - GROUNDWOOD
Polymer Pitch particles
/mL
. . _
Control 106,250
Polymer of Invention 52,500
Competitive Product A 71,250
Note: Following the addition of polymer, each sample was agitated for 2-5
minutes at 500-800 RPM prior to filtering.
TABLE [V - SULPHITE PULP
Polymer Pitch particlcs
/mL
_ _
Contro] 63,750
Polymer of Invention 30,000
Competitive ~roduct A 35,000
Note: Results obtained on samples after agitation for 2-5 minutes a-t 500-800
RPM prior to f-iltering.
'I'ABI,I V - SUI,PIII'I`I` PlJLI'
_ _ .
r~O 1 yll,cr 1~ i tcl~ lrticl~
(.ontrol 231,875
I'olylll~r ol` l~lvellti~o 10(),()n()
Co~ )otit~ive ~ o~lJ~t ~ 82,5()()
Note: Followillg the ad(litioll ol` polylller al)ove salll[)les were agit.lted for 2-5
minutes at 500-8()() Rl'M pl:ior to filtering.
~5~9~4
TABLE V I - GROUM)WOOD PULP
Polymer % of pitch particles
fixed onto fibres by
polymer.
Polymer of invention 45o
TABLE VII - SULPHITE PULP
Polymer % of pitch particles
fixed onto fibres by
polymer.
Polymer of invention 55~o
competitive product A 53O
From the abovc it is obvious that an advance in the paper treating art
has been achieved.
