CA2415911A1 - Retention aid additives for paper making - Google Patents

Abstract

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.

Description

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 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

2 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 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.

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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Claims (4)

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.