ADDITIFS SEQUESTRANTS POUR LA FABRICATION DE PAPIER

RETENTION AID ADDITIVES FOR PAPER MAKING

Abrégé anglais

A pulp and paper additive comprising a selective protein recognition function
that
specifically links a component of a papermaking solution. The invention
provides an
improved process of paper manufacture and novel paper making additives of use
therein.

Revendications

Claims:
1. A pulp and paper additive composition comprising a selective protein
recognition function that specifically links a polymeric organic fibrous
material
component of a papermaking solution.
2. An additive as claimed in claim 1 wherein said component is selected from
the group consisting of cellulose, hemi-cellulose, xylan, mannan, lignin,
fibers, filler
and a binding agent.
3. An additive as claimed in claim 1 or claim 2 wherein said protein is
selected
from the group consisting of cellulase, a cellulose binding domain, xylanase
and a
amylase.
4. An additive as claimed in any cane of claims 1 to 3, wherein said filler is
selected from the group consisting of clay, kaolinite, titanium dioxide and
calcium
carbonate.
6

Description

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1410
RETENTION AID ADDITIVES FOR PAPER MAKING
FIELD OF '>-t-1E INVE:NZ'ION
This invention relates to paper making processes and additives of use therein.
BACKGROUND OF THE INVENTION
Modern papers are a sophisticated blend of l7bers. tillers and polymers
wherein during manufacture synthetic retention aids are reduired to enhance
the
deposition of tillers and tines onto the fibers before sheet formation.
Without
I ~ retention aids, most of the tillers and some of the tines pass throubh the
sheet and
remain in the white water. Poor retention lowers product quality and paper-
machine
efficiency, and v-vaster raw material. Loss of tins is especially si~niticant
in
thermomechanical and chemi-thcrmomechanical pulping processes, which produce a
significant quantity of fines in suspension.
?U Typical retention aids include high molecular weight organic polymers, with
either positive. nebative or net neutral charges. Cationic polymers are
frequently
employed to bind with cellulosic fibres, which naturally possess a negative
char;~e.
Unfortunately. conventional "effective'" retention aids cause everything to
stick to
everything else. Fillers form large aggregates instead of uniformly depositing
onto
?5 fibers and unwanted fiber-fiber tlctceulation gives pocn~ sheet formation.
A
fundamental problem is that retention aid adsorption is not selective in that
tines,
tillers and fibers compete for the retention additives.
Pulp and Paper Canada, 81. ~4, 1980- R.t-I. felton, L.l-1. Allen, and H.M.
Nugent and TAPPI J. C8, 91, 1985 - R.H. t'elton describe the use of high
molecular
;0 weight organic polymers as retention aids far pulp systems, and compare the
effects
of charge on rmention aid effectiveness.
"Pulp and Paper: C.'hemistry and Chemical 'technology, Vol 2", Chap 8, 'P.N.
Kershaw, ed., John W'iley and Sons. New York, 1981 - .1.P. Casey describes the

CA 02415911 2003-O1-02
impact of the loss of cellulosic tines on paper properties, the justification
for the need
for retention aids for effective paper formation arrd the economic impact of
tine fiber
loss.
''Handbook for Pulp and Paper Technologies". Chap I~. C'PPA/TAfPI joint
textbook committee. 1982 - G.A. Srnook describes, in a general way, the role
of
retention aids in papermaking in that prey facilitate the aggregation of
tibers and tine
materials of cellulosic tines or tillers, which are otters less than about >
microns.
J. Wood Chem. Technol., 9, 407, 1989 - S. Roy, M. Desrochers, and I..
Jurasek describes the use of proteins as potential retention aids, including
lysozyme,
I U trypsinogen. myoglobm, carbonic anhydrase and protease, Proteins were
chosen
based on their charge characteristics, without any consideratirm of their
ability to
bind chemically to the materials in a papermaking suspension, i.e., the
expected
mechanism of action for these proteins was essentially equivalent to that
observed
with high molecular weight polymers currently used in industry. I lowever, the
results
1 ~ suggested that, in addition to electrostatic interaetions, some other firm
of binding
was probably also occurring. The isoelectrie point of the proteins had a
significant
effect on binding, suggesting that most of the binding was based on
electrostatic
interactions.
U.S. Patent x.998, I 83, issued December 7, I 99c) - G.N. l.e Fevre and 8.;1.
?0 Saville, describes the immobilization of enzymes, and means to ensure that
enzyme
activity is retained and maximized.
SUMMARY ()I= 'i~l-IE 1NVIN hiGN
''> It is an object of the present invention to provide an improved process of
paper manufacture and novel paper making additives of use therein.
Accordingly, in one aspect, the invention provides a process of preparing
selective paper making additives by immobilizing cellulaseicellulosc binding
domain
(CBD) onto a clayikaolinite support, and by co-immobilizing cellulase/(C:C3D)
and cx-
>i) amylase onto a clay/kaolinite support. 'hhe cellulase/(.'BD moiety
selectively binds to
cellulose in a papermaking suspension, while amylase will bind to starch. The
product obtained is therefore highly selective, possessing specitic
recognition sites
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for starch and cellulose. Furthermore, the immobilization support
(clay/kaolinite) is a
commonly used tiller within paper.
The invention in one aspect, thus, provides a pulp and paper additive
composition comprising a selective protein recognition function that
specifically
links a polymeric organic fibrous material component of a papermaking
solution.
The additive is preferably selected From the group consisting of cellulose,
hemi-cellulose, xylan, mannan, (ignan, fibers, tiller and a hinding agent.
Preferably, the protein is selected ii-o m the group c~>nsiatir~~~ of
cellulase. a
cellulose binding domain, xylanase and a amylase.
I() The tiller is preferably selected from the gi°oup consisting of
clay, kaolinite,
titanium dioxide and calcium carbonate.
BRIEF E)ESC"RIPTION OF 'f HE DRAV~~ INGS
f > In order that the invention may be better understood, preferred
embodiments
will now be described by way of example only with reference to the
accompanying
drawings, wherein
Fig. 1 is a graph showing immobilized enzyme activity for different loadings
of a
clay, and
?0 Fig. ? represents scanning election microscope images of clay onto cotton
titers.
DETAILED DESCRIPTION ()F PREFERRED t:MB()D(MENrI S
l Ise of the process of the invention for starch coatings is described herein.
Starch coatings ("sizes") are typically utilized to till in gaps or voids on
the
surface of the sheet. 'These coatings may be administered en a size press. or
by tub
sizing. In the former operation. the rollers (or nip) are t7ooded with starch
solution,
which is then delivered and attached to the paper by absorption as it passes
between
the rollers. The process must he carefully controlled to avoid non-uniform
30 distribution of the sizing agent onto the paper stock. In particular, the
paper machine
may need to run at relatively low or moderate speeds to ensure proper
attachment of~
the solids in the sizing solution. In a tub sizing operation, the sheet passes
throu~~h a

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shallow tub or bath that contains the starch solution: excess solution is
subseduently
removed by passing the sheet through a set ol~rollers.
In either type of process, the objective is to achieve a uniierrr~ coating of
the
sizing agent onto the paper. Selective or controlled deposition of starch onto
the
underlying cellulosic component of the paper will improve sheet formation and
coating uniformity. 'T'he additives described herein, which prc>mute selective
binding
between paper constituents and starch theretor-e improves deposition of starch
coatings onto paper.
Enzymes were immobilized onto clay/kaolinite, through a cross-linking
process, adapting an existing immobilization technolo~,y, in accordance with
aforesaid IJSP >,998,183, to a-amylase, cellulasc:. and the cellulose-binding
domain
(CBD) of cellulase. ~hh~ effectiveness of the intelligent paper additive was
established through adsorption studies, followed by examination of fibers
using
scanning electron microscopy. Measurements ot~ the activity of the soluble and
I > immobilized enzyme provided additional evidence regarding the
effectiveness of the
II11Il10bIIIZal1011 procedure.
Examines
Example (: Experiments with cellulase immobilized on kaolinite
For a variety of diffierent immobilization conditions, measurements of the
?0 activity of soluble cellulase betore and ai-ter immobili-r_ation were
conducted, based
on the production of reducing sugars. '!he activity of the immobilized enzyme
was
affected by the duration of immobilization, and the relative concentration of
cellulose
to clay. For the support modification step, which takes place over 1.~ to 10
hours, the
glutaraldehyde concentration typically ranched between I and ~°/,
(v/v). For the
_'~ immobilization step. the modified support was incubatmi in enzyme
solution,
comprised of raw enzyme solution diluted either ~, 10, or 20 told, to
establish the
effect of protein concentration on the immobilization process. The activity of
the
immobilized enzyme for some different loadings of clay and immobilization
conditions is shown in Figure 1. 'these data indicate that cellulose is
attached to clay,
30 and that this configuration recognizes the Ce111110Se Ill tile SOILIll011,
establishing that
cellulose and clay can be attached in this manner.
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Adsorption studies with the immobilized cellulase were conducted by
incubating the bioadditive in a solution containing cotton (c.cllulose)
tibers. As a
control, tibers were also incubated in a suspension of clay alone. Figure 2
compares
the SEM images of native cotton tibei°s. cotton tibers exposed to clay
only, and
cotton tibers incubated in cellulase imn~ubili~cd onto clav, wherein
(aj is untreated cotton fiber:
(b) is cotton tiber incubated in clay suspension:
(ej is cotton fiber incubated in clay-cellulase complex
As shown in F' ig. 2, much more cloy is attached to the cotton when the clay
is
I () coupled to cellulose than ii' the cotton is incubated in clay alone. The
selective
interaction between cellulose and cellulose (cotton) thus facilitates greater
deposition
of clay.
Although this disclosure has described and illustrated certain prefierred
embodiments of the invention, it is to be understood that the invention is nut
1 ~ restricted to those particular embodiments. Rather. the invention includes
all
embodiments which are functional or mechanical equivalents of the specific
embodiments and features that have been described and illustrated.
(.)

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