CA1326317C

CA1326317C - Method of controlling microbiological deposits on paper making equipment and paper obtained thereby

Info

Publication number: CA1326317C
Application number: CA000607955A
Authority: CA
Inventors: Kjell Ingemar Korneback
Original assignee: WR Grace and Co Conn
Current assignee: Veolia WTS USA Inc
Priority date: 1988-08-11
Filing date: 1989-08-10
Publication date: 1994-01-18
Anticipated expiration: 2011-01-18
Also published as: EP0354889A2; NO893226L; FI91007C; ZA895715B; EP0354889A3; NO175402B; NZ229991A; SE467667B; SE8802873D0; SE8802873L; FI893788A; FI91007B; NO175402C; JPH02118198A; FI893788A0; AU3919089A; AU615095B2; JPH086279B2; NO893226D0

Abstract

ABSTRACT
The invention relates to a method of controlling productivi-ty disturbing microbiological deposits, e.g. slime, on paper mak-ing equipment, which method is characterized by applying to any locus or surface of said equipment a deposition-controlling amount, preferably at least about 0.1 parts per million of dilu-tion water, of a cationic polymer or a cationic surfactant or a mixture thereof.
Said application is preferably performed by spraying an aqueous solution of said polymer or surfactant directly onto the equipment to be cleaned.
The invention also relates to the improved paper prepared by such a method.

Description

TITLE OF THE INV~NTION
A METHOD OF CONTR~LLING MICRO~IOL~G~CAL DEPOSITS ON PAPE~
MAKING EQUIPMENT AND PAPER OBTAINED THEREBY

-Technical field of the invention The present invention relates to an improved method of pro-viding a clean sheet forming equipment and the like for paper pro-duction and, more particularly, to chemical treatment of papermaking equipment to control produ~tivity disturbing, microbiologi-cally originated depo~itH thereupon The invention also relates to the paper produced by said improved method Backaround of the invention The manufacture of paper typically involves the proces~ing of a carefully prepared agueous fiber suspension to produce a hi~hly uniform dry paper sh-et Three steps included in the typi-cal process are sheet forming, where the suspension is directed over a porous mesh or "wire" upon which fibers are depo~ited while liquid filters through the wire; sheet pressing, where the formed sheet is paesed through pressee covered with porous "felt" to extract retained water from the eheet, to improve the sheet' B uni-formity, and to impart surface quality to the sheet; and paper dryin~, where residual water i~ evaporat-d Erom the sheet The sheet may then be further proceEsed into the fini~hed paper pro-duct It is well known that evaporation of water is energy inten-~ive and thus relatively expeneive Consequently, efficient paper makino i~ d-p-ndent upon xtracting wat-r during the forming and pr-~in~ op-ration~, and avoiding ~he-t defect~ which render the dried ~h-et un~it for u~e Felts and wires are thus particularly important b-cau~- th-y aff-ct not only wat-r r-moval but, because o~ th-ir intimat- contact with the h--t, the quality of th- sheet it--lf D-po-it~ allow~d to coll-ct on the wir- can aff-ct its wat-r r-moval ffici-ncy and can be tran~f-rr-d to the sheet mate-ri-l to cr-at- d-f-ct~
Th- quality of th- aqu-ou~ fib-r ~u~pension used to produce th- ~h--t i~ dep-nd-nt upon many factor~, includino the wood and '~
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~ater used as raw materials, the composition of any recycled mate-rial added to the process, and the additivea used during prepara-tion of the suspension. Thu~ a variety of di~solved or suspended material3 can be introduced into the manufacturing process, inclu-ding both inorganic materials ~uch as salts and clays, and mate-rials which are organic in nature such as resins or "pitch" from the wood, as well as inks, latex, and adhesive~ from recycled pa-per products. A build up of deposits contaning inorganic and/or organic materials on felts and other sheet forming equipment dur-ing the manufacturing process i8 recognized as a troublesome ob-stacle to efficient paper making.
Another particularly troublesome deposit is the slimy gela-tinous material produced by certain bacteria that naturally occur in the paper making system. (This material i~ hereafter referred to as "slime"~. Since the conditions in a paper machine system normally are very favourable for the growth and reproduction of bacteria the problems with slime deposit build-ups on paper machine part~ often become severe and will, if not inhibited, lead to significant productivity diaturbances in the paper making pro-cess.
A typical problem caused by slime deposits occurs when big lumps oE built-up slime fall down from the position where they were formed onto the paper sheet, thus causing a sheet defect and/or break.
Methods of guickly and effectively removing slime deposits Erom the paper mill equipment are of great importance to the indu-stry The paper machines could be shut down for cleaning, but ceasing operation for cleaning i8 undesirable becau~e of the con-sequential loes of productivity. On-line treatment is thu~ great-ly preferred where it can be effectively practised.
The most commonly and successfully used way of removing slime from paper machine equipment has been to treat the aqueous fiber suspension with various type~ of biocides. Examples of such biocide~ are methylene-bis-thiocyanate, 5-chloro-2-methyl-4-iso-thiazolin-3-one and 2-methyl-~ ioothiazolin-3-one.
~ hemicals of this type are, however, often very unpleasant to handle and are from an environmental and health and safety point of view often regarded as objectionable. For the~e reasons there is a strong driving force within the industry to, wherever :,,. : . .
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3 ~3`2~317 it i~ po~sible, ~oid the use of biocide~ in the paper ~king pro-ce~.
Another approach to slime control has been to combine the biocide treatment of the fiber ~u~pension with addition o~ anionic di~per~ants. The ~ucces~ of this approach has, however, been very limited, especially in paper ~y~tems working with a high de~ree of white water closure.
Yet another approach to slime control has been to treat the Fiber suspension with enzymes. The commercial succe~ of this method has, however, also been very limited.
With this in mind it is easy to realize that a method which would enable effective control of slime deposit~ on paper machines, without the di~advantage~ connected with biocide~, would be a significant step ahead in the progress of a more environment-ally acceptable paper makin~ process.
It has now unexpectedly been found that productivityproblems cau~ed by the deposition of or~anic matter derived from microbiological activities can be effectively controlled without any use of toxic biocides or while using reduced amounts of such biocides, viz. by the use of certain polymers or surfactants and without incorporating the substance~ into the paper pulp. The polymers or surfactants referred to are previously known per se, but a~ Far a8 we know they have never been used or su~g~sted for use in the way claimed by the present invention. In this respect and with respect to the prior art mentioned above reference i8 made to the following prior art: CA 1,150,914 issued August 2, 1983, EP 82400266.1 published August 25, 1982, US 3 582 461 issued in June 1971 and US 4 190 491 issued February 26, 1980 which all relate to pitch control in connection with paper making; UK 1 486 396 published September 21, 1977 and US 4 140 798 issued February 20, 1979 which both relate to chemical substances which are known per ~e to inhibit the growth o~ microorganism~t and GB 2 186 895 published November 1, 1989 which disclo~es a group o~ chemicals which are use~ul in accordance with the present invention but which are not suggested for such a use therein.
G-A-r~l umm~LY oF th- invontion Thus, in ac~ordance with ths present in~ention it has unex-pectedly been Found that certain cationic polymers or cationic surfact~nts or mixtures th-reof can be eFFectively used, without ~; ~any noxius biocides or in combinaticn with such biocides in greatly reduced amounts, to control the deposition in connection ,,. ~
.

4 132~3~7 - ~ith paper making o~ productivity disturbing microbiologi~al depo~its, ~aid cationic polymer~ or surfactants being utilized in a novel way Therefore, one object of the invention i~ to provide an im-proved paper making method where the deposition of organic matterof the above-mentioned type i~ controlled, i e prevented or inhi-bited completely or at least to a very great extent if not already having been formed, or reduced or dispersed completely cr to a great extent if already having been formed The invention i8 espe-cially intere~ting in connection with the control of ~lime cau~edby alime-forming microorganisms Another object of the invention is to provide a new method, by which the use of toxic biocides i~ eliminated or greatly reduc-ed, i e to provide a paper mill deposit control method which i8 environmentally acceptable Still another object of the invention i~ to provide a new method, by which the incorporation of chemicals into the paper pulp is avoided or reduced A further object of the invention is the provi~ion of a method, by which considerably reduced concentrations of chemical~
are utilized to control the depo~it problems referred to above A still further object of the invention i~ the provi~ion of a method, by which the productivity and product quality in paper making is increased A ~till further object of the invention i8 the provi~ion of a high quality paper whenever manufacturod by the method claimed These and other objecte and advantage~ of the present inven-tion will become apparent from the following more detailed de-scription of the invention p-tail~1 d--criDt~Qn_s~ th- inv-ntion In accordanc- with th- inv-ntion th- abov--~-ntion-d obj-ct-and oth-r ob~-ctc ar- acco~pli-h-d by th- pro~i~ion ot a ~-thod of controllino productivlty di~turbin~ ~icrobiolooical d-po~it- on pap-r ~akin~ quip~-nt, caid ~-thod b-lno charact-riz-d by pply-ino to any locu~ or urtac- ot ~ald pap-r ~akin~ quip~-nt which locu- or curtac- ic c-ncitl~- to build-upr ot ~uch ~icrobiolooical d-pocltc, a d-po~ition-controlllno a~ount o~ a d-po~it~on-con-trollino ~ub~tanc- ~-l-ct-d tro~ th- ~roup con~i~tin~ ot cationic .
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' _- 5 1326317 polymer~ and cationic ~urfactants, which includes mixtures thereof.
As was mentioned above the term "control" should be ~iven a broad sense in the meanin~ of the invention. Th~t is, accordin~ to the invention it has unexpectedly been found that the application of the cationic polymer or surfactant or mixture thereof can be utilized to prevent or inhibit the formation of deposits as well as to dissolve or disperse deposits which have already been formed.
With reference to the meaning of the expression "any locus or surface of the paper making equipment which is sensitive to build-ups of such deposits" or similar, it should be noted that the general meaning thereof i8 that the cationic polymer or ~ur-factant i8 not incorporated into the pulp or paper but i8 applied onto any strate~ical part or position of the paper making equip-ment. Thus, by experience a person skilled in the art knows what locus or surface shows the ~reatest tendency of forming depo~its, i.e. where the cationic polymer or surfactant ~hould primarily be applied to obtain the best results. Of course this also means that the polymer or surfactant can be applied onto more than one such locus or surface if necessary or advisable.
The invention is generally applicable to any water soluble cationic polymer or surfactant of the type reEerred to, which pri-marily means that an agueous solution of said polymer or surfac-tant is utilized. This in turn means that an especially preferablemethod of applying the cationic polymer or surfactant onto said locus or surface is by means of a spraying operation, as this is generally a simple operation and ae such an operation has been shown to be very effective in connection with the invention. That i~, it has unexpectedly been shown that very low concentration~ of the polymer can be utilized in this way for outstandiny results.
The method claimed iu generally applicable to the control of any deposition caused by microor~anism~, but it has been found to be e~pecially interectin~ to control deposits cau~ed by bacteria, e.~. ~lime caused by slime-formin~ bacteria.
A~ the major characteristic feature of the invention iB the application of the cationic polymer or eurfactant directly onto the locu~ or susface to be treated, said polymer or ~urfactant bein~ utilized in unexpectedly low concentrations, the preci~e , . , ' ,. , . ~ :

132~31~
.,ature of the polymer or ~urfactant to be u~ed is not the main characteri~tic of the invention, provided it i8 of the cationic type. Thus, a considerable variety o~ diff0rent polymer~ and ~ur-factants may be u3ed within the ~cope of the invention, i.e. alao based on previously known microbiocidal activitiee. However, a number of especially preferable polymers and surfactants will be di~closed below. TypicAlly a water ~oluble polymer or ~ur~actant i8 used.
Thus, according to one preferable enbodiment of the inven-tion a cationic polymer is utilized which has a molecular weight within the range of 1,000 - 5,000 000, e.g. between about 10,000 and about 300,000. A preferable embodiment within said ranges i~
from about 20,000 to 300,000, especially from about 20,000 to 50,000. Another preferable range is from abou~ 10,000 to 50,000.
As to the oationic ~urfactant a preferable range of the mo-lecular weight thereof i~ between about 200 and about 600.
Accordiny to another preferable embodiment of the invention an aqueous solution of the polymer or surfactant i~ used which is ~ub~tantially free from anionic macromolecules.
The charge density of the compounds embodied by the inven-tion should be in ~ range of between ~bout 0.5 milliequiva-lento/~ram and 20 milliequivalents/gram. A preferable embodiment within ~aid range is about 1-10 milliequivalents/gram, especially about 2-B milliequivalents/~ram.
One preferred ~roup of cationic polymers according to the invention compri~es dicyandiamide-formaldehyde condensation poly-m-rs. Polymers of thi~ type are diJclosed in many pAtents. US
2,774,749 issued before 1963, US 2,829,126 issued April 1, 19 58, GB 1,193,294 filed June 1967, DE 917,392 published 1949, FR 1,484,381 published 1966, DE 2,017,114 published 1970, JP 75,111,864 published 1975, JP 73,16,067 published 1973, DE 2,515,175 publi6hed October 9, 1975, CH Application 9,527/72 filed July 23, 1972, DE 2,451,698 published May 22, 1975, DE 1,128,276 published 1962, DE 2,403,443 filed January 25, 1974, FR 1,414,407 published 1965 and DE 2,321,627 published in December 1973 represent some examples thereor.

Another prs~erable ~roup of cationic polym-r~ to be used in accordance with the invention io those polymers which are formed by r-action b-twe-n opihalohydrins and varioue amine~. The mo~t r - prererred epihalohydrin in thi~ r-~pect i~ epichlorohydrin, and as examples o~ ~uitable amine~ re~erence can be made to dimethylami-.

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7 ~ 7 ne, diethylamine, methylethylamine, ethylene diamine, triethanola~ine and a poly~lkylene polyamine Example~ thereof includ~ tho~e polymers which a~e o~tained by r~action between ~ polyalkylene polyamine and pichlorohydrin, a~ well a~ those polymer~ which are obtained by reaction between pichlorohydrin, dimethylamine and eith~r ethylen~ diamine or a polyal~ylene polya~ine A typical amine which can b~ utilized i~ N,N,N',N'-t-tr~-methyl-thyl-n- di~-mine as well a8 ~thyl~ne diamine used to~ether with dimethylamine ~nd triethanol~mine Polymer~ of this type include those poly~ers which have the rOllowin~ g~neral formula ,0/ I r,j 1 \
CWP2-+~ CH2 1 ~ C~ CN2 -tl- ~2 0~1 1 _ CH3 ON
~ ~ ~ J 2 wh-r- A i~ a number within the r~n~o of 0-500 Pr-t-rred cationic polymer- Or thi~ inv-ntion al~o includ-tho-- made by reactin~ dimethylamine, di-thylamine or methyl-thyl-amin-, prererably ~ith-r dimethylamine or diethylamine, with an pihalohydrin, prer-rably pichlorohydrin Polymers of this type ~r- di~clo~-d in U S Pat-nt No 3 738 9~5 and Canadian Pat-nt No 1 096 070. Such polymers are commQrc$ally available a~ Age~loc~
A-S0, Agerloc~ A-50HV and Age~loc* B-50 ~rom CPS Chemical Company, Inc., Or New JersQy, U8A. ThesQ three products are reported to contain as their active ingredients about 50 percent by weight Or polymers having molecular weights Or about 75,000 to 80,000, about 200,000 to 250,000 and about 20,000 to 30,000, respectively. Another commercially available product o~ this type i8 Magnirloc* 573C, which is marketed by American Cyanamide Company or New ~ersey, U8A, and is believed to contain as its active ingredient about 50 percent by weight o~ a polymer having a molecular weight Or about 20,000 to 30,000.
Another prererable group o~ cationic polymers ror use in ~t5$j~accordance~with the invention compr$se~ polymers derived ~rom ~thylenically unsa~urated monomers containing a quaternary * Trade-mark .: . .. . . .

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-~ ~32~317 ~~mmonium group Such polymer~ m~y comprise homo- and copolymers of vinyl compounds, such aa vinyl pyridine and vinyl imidazole, which may be quaternized with, say, a Cl-Clg-alkyl halide, a benzyl halide, especially a chloride, or dimethyl or diethyl sulphate, or vinyl benzyl chloride, which may be quaternized with for in~tance a tertiary amine of Eormula NR1R2R~, wherein R1, R2 and R3 are each and independently lower alkyl, preferable with 1-~ carbon atom~, with the proviso that one of ~aid groupa R1, R2 and R3 may be C1-C18-alkyl; allyl compounds such as diallyldimethyl ammonium chloride; or acrylic derivatives such as dialkyl aminomethyl-(meth)acrylamide, which may be quaternized with for in~tance a C1-C1g-alkyl halide, a benzyl halide or dimethyl or diethyl ~ulphate, a m-thacryl~mido propyl-tri~C1-C4-alkyl, ep-cially methyl) ammonium ~alt, or a (meth)acryloyloxy-thyltri~C1-C~-alkyl, -p-cially m-thyl) a~monium ~alt, caid ~alt bein~ a halid~ p--oially a chlorid-, m-tho~ulphat-, etho~ulphate, In thi4 context it should alco be added that throughout the de4cription and claimc the term "lower alkyl" means an alkyl group containing 1-6 carbon atoms, unles~ otherwi4e stated In the ca~e of copolymers as referred to above the monomers can be copolymerized for instance with a ~meth)acrylic derivative ~uch as an acrylamide, an acrylate- or methacrylate-C1-C1g-alkyl e4ter or acrylonitrile, or an alkyl vinyl ether, vinyl pyrroli-done, or vinyl acetate Typical ~uch polymer~ contain 10 to 100mole percent of recurring unit~ of the formula ~1 ~3 -q2 C .
I
COO!CN2J2! ~ X-and 0-90 mole percent of recurrin~ unit~ of the formula I

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1326317 ~
wherein R1 represent~ hydrogen or lower alkyl, preferably alkyl with 1-4 carbon atoms, R2 represent~ a long chain alkyl group, typically of from 8 to 18 carbon atom~, R3, R~ and Rs ~ach and independently repre~ents hydrogen or lower alkyl, while X repre-sents an anion, typically a halide ion, a metho~ulphate ionS an - ethosulphate ion.
Other quarternary ammonium polymers derived from an un-saturated monomer include homo and copolymers of diallyldimethyl ammoniumchloride which contain recurring or repeating units of the formula + cf j~ CNZ~

~H~ CN2 _ where Z represento monomeric units, like for in~tance a ~meth)acrylic derivative such as an acrylamide, an acrylate- or methacrylate -C1_c18-alkylester or acrylonitrite, or an alkyl ~inyl ~th-r, ~inylpyrrolidon- or vinyl ac-tat-, m i~ within th-ran~- of S-100X and n ic ~ithin the rang- of 0-95X
In thi~ r-cp-ct, it chould b- not-d that thie polym-r ehould b- r-~ard-d a~ ~cubctantially lin-ar~ cinc- althou~h it contain-oycllc ~roUp~ng-, thec- ~roupinge ar- conn-ct-d alon~ a lin-ar ahain and th-r- i~ no croca-linkin~
Oth-r poly~-rc which can b- u--d and ~hlch ar- d-rived from uncaturat-d monom-rc includ- thoo- havin~ th- for~ula ~5 _ _ X- , X-~'' ' .
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~~ where Z and Z', which may be the ~ame or difforent, are -CN2CH=CHCH2- or CH2-CHOHCH2-, Y and Y , which ~ay be the ~ame or different, ar~ eith-r X or -NR'R", X io a halog~n of atomic wei~ht ~r-at~r than 30, n i~ an int-~r of from 2 to 20, and R' and R
(i) ~ay be the ~amo or different alkyl group~ of from 1 to 18 car-- bon atomfl, optionally substituted by 1 to 2 hydroxyl group~; or ~ii) when tak~n to~ether with N repreoent a saturatod or unsa-turated rin~ of from 5 to 7 ~toms; or Ciii) ~h~n taken to~ether with N and an oxygen atom represent the N-morpholino group; espe-cially poly(dimethylbutenyl)ammonium chloride-bio-~triethanol ammonium chloride) Another cla~s of polymer which can be used and which is de-rived from ethylenically un~aturated mono~2rs includes polybuta-dienes which have been reacted with a lower alkyl amine and some of the re~ulting dialky-l amino ~roups are quaternized ln general, therefore, the polymer will possess recurrin~ units of the formula ~ CH2 ~ tH2-oH)- e) -~CN ~ J- ~nd ~) -(cHr H~-CN ~N2 ~N2 H2 ~ H2 N2 N3 al2 CN2 N2 ~ ~3 X- ~2 in the molar proportions a b c d, respectively, where R represents a lower alkyl radical, typically a methyl or ethyl radical It should be underotood that the lower alkyl radicals need not all be the same Typical quaternizing agents include methyl chloride, dimethyl ulphate, and diethyl sulphate Varyin~ ratios of a b c d may be u~ed with the amine amount- (blc) bein8 ~enerally from 10 to 90 X with (aId) bein~ from 90 to lOX These polymer~ can be obtained by reactin~ polybutadiene with carbon monoxide and hydro-~en in the pre~ence of an appropiate lower alkyl amine Other cationic polymers which are capable of interactin~
with anionic macromolecule~ and/or ~limy material in paper making pulp may al~o be u--d within the cope of thi~ invention These may include catlonic tannin derivativeo, ouch a~ those obtained by a Mannich-typ- reaction of tannin ~a conden~ed polyphenolic body) with formald-hyd- and an amin-, formed a~ a ~alt, e ~ acetate, formate, hydrochloride, or quaternized, a~ well as polyamin- poly-\~ .

, 11 ~b 132~317 ner- which have been cros~-linked, ~uch a~ polyamideamine/poly-ethyl~ne poly~mine copolymer- cros~-linked with, ~ay, epichloro-hydrin Yet anoth~r ~uitable type o~ polymer i~ that ~orm-d by r-acting a polya~ido amina with epihalohydrine Such oro-~linked polyamidoamines ar- de~cribed in US patent~ 3,250,66~, 3,B93,~85, ~,642,572 and ~,250,299, AcGording to a preferable embodiment of the invention the cationic ~urfactant is of the general formula [I ~ ~ r wherein e~ch R i8 independently selected ~rom the ~roup consistin~
o~ hydrogen, alkyl ~roup- havin~ bet~een about 1 and 22 earbon atoms, aryl groupr, and aralkyl group~, t least one of ~aid R
~roupc being an alkyl ~roup havin~ at least about 8 c~rbon atoms and preferably an n-alkyl group having between about 12 and 16 earbon atom~; and wh-rein X~ i8 an anion, pr-f-rably a halide ion, e.g. chloride. Mi~es of these compounds can also be used as the surfactant of this invention.
Pref~rably two ot the R group~ of the urfactant are ~elect-ed from the group con~istin~ of methyl and ethyl, most preferably methyl Pro~orably al~o one R group is selected ~rom the aralkyl group~ Ph-CH2- and Ph-CH2-CH2-, where Ph i~ phenyl The mo-t pre-~erable aralkyl group i8 benzyl Thu~, particularly useful ~urfactants include alkyl dimethyl benzyl ammonium chloride~ havin~ al~yl group~ or between about 12 and 16 carbon atom~ One eom~-rcially available product ot this typ- includ-~ a ~ixture Or alkyl dimethyl benzyl a~monium chlorid-~ wh-r-in about 50X of the ~ur~actant ha~ a Cl~H2g n-alkyl group, about ~0X ot the ~urtactant has a C12H2s n-alkyl group, and about 10X ot the ~urtactant has a C16N33 n-alkyl group Thir pro-duet lo known p-r - ror it~ mlcroblocldal ~-ctlv-n-~
Ao wa~ ment~oned abov~ lt ha~ be-n found that when the cat-ionlc polymors and/or catlonlc ~ur~actanto o~ thic invention are appli-d dir-ctly, jr---r-bly by ~praying, onto paper ~achine parts at low eonc-ntration~ ~llme and oth-r microbiological deposit~ on .

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12 13263~7 , ~aid parts or equipment are aigniEicantly reduced or eliminated.
More specifically, it has been found that generally such a low concentration of the polymer or surfactant as from about 0.1 parta per million of dilution water will give a depo~it-reducing effect.
Preferably Yaid amount i9 from about 5 parts per million of dilution water where continuous treatment is used, while preferably from about 50 parts per million of dilution water is utilized during the application period where the application is intermittent. As to the upper limit this can easily be determined by a person skilled in the art in each specific case, but in general said amount or concentration is kept at as low level as possible to avoid an unnecessary contamination of the paper therewith. A preferable upper limit i~ 500 parts per million of dilution water.
While the mechanism of the phenomenon obtained by this in-vention is not completely understood, it is believed that the cat-ionic components of this invention disperse the slime at an em-bryonic stage thus preventin~ build-up of big lumps. The recharged cationic dispersed slime can then easily be removed from the system together with the paper sheet. In any case the tendency of slime to pass by paper making equipment rather than adhering to the same is greatly increa~ed by the treatment in accordance with this invention.
As was mentioned above the polymer or surfactant of this invention i8 applied, such as by spraying, in aqueous solution directly onto the equipment being treated.
As has also been mentioned the aqueous solution containing the cationic polymer and/or ~urfactant should be substantially free from anionic macromolecules. These anionic materials include natural materials such as wood lignins, by products of chemical pulping such as ~odium ligno~ulfonates, and synthetic materials such as polyacrylates.
The polymer~ and surfactants of this invention are typically ~upplied a~ liquid compositions comprisin~ aqueous solutions of the polymer and/or surfactant. Polymer concentrations of the com-po~itions may ran0e from such relatively dilute solutions having polymer concentrationfl suitable for continuou~ application up to the solubility or gellin~ limit~ of the polymer, but ~enerally the composition~ are relatively concentrated for practical shipping , , .; '' , ' , ., ' ., ' ' , 13 13~17 ~nd handling purposes. Moreover, the liguid compositions may com-prise additional materials which enhance the dissolution of the polymers 80 as to allow more concentrated compositions to be ob-tained. As an example of such materials reference c~n be made to alkoxyethanols such as butoxyethanol. Suitable agueou~ composi-tions will generally contain between 5 and 50 percent by wei~ht of the cationic products of this invention. It should also be understood that, if desired, the compounds embodied by this invention can be added in solid form, e.g. as ~ranulates.
The most appropriate treatment dosa~e depends on such system factors as the soiling level of the adhesive material, and whether cleaning is continuous or periodic. Even liquid compositions com- -prisin~ relatively high concentrations of a polymer of the inven-tion (for example 50X~ may be employed at full ~trength (lOOX a~
the liquid composition) for example by spraying the undiluted liquid composition directly onto the machine parts. However, par-ticularly where continuous treatment is practiced, the composi-tions may be advantageously diluted at the treatment location with clean fresh water or other aqueous liquid. Where necessary for water economy, proces~ water may be adequate for dilution.
Generally the method claimed can be performed continuously in order to continuously control the deposits referred to. In some cases, however, continuous treatment is not practical and then the treatment with the cationic polymers and surfactants of this in-vention may be periodic. For example, aqueous solutions of thepolymer or surfactant may be sprayed on the deposited surface un-til said surface is satisfactorily cleaned, and the sprayin~ may then be discontinued until further treatment becomes necessary.
The invention will now be further described by means of the ollowin~ non-limitin~ example.

~xamDle A commercial paper machine of twin wire type produces news-print paper. In order to inhibit microbiological ~rowth and the correspondin~ occurrence of slimy deposits biocides are added to the white water circulation system of this machine.
The addition points of the biocides have been fixed to the wire chest and to the shower water tank. Further, a cationic poly-mer of dicyandiamide-formaldehyde type is used as deposit control : . .

-`- 1326317 ~id and as ~uch added to the fiber suspension in a position corre-sponding to the suction side of the Deculator pump. The complete dosage situation as well as machine capacity ~tatus is shown in table 1, No A.
In the first trial the addition point of the ~olvmer was moved from the pulp suspension to the water u~ed for the high pressure shower system, thus enabling the diluted cationic polymer to directly, through the high pressure spray bars, come in contact with machine parts sensitive to slimy deposition. The actual sur-faces connected to the high pre~sure shower system is the top and bottom wire, the forming roll, the pick up felt and the press felts. The effect of the new treatment on the machine statu~ i8 shown in Table 1, No B.
In the second trial two measures were taken. Fir6tly the biocide addition to the shower water tank was interrupted. Second-ly the polymer shower treatment was extended to comprise also the low pressure shower system. In addition to the first trial it was by this extension also possible to reach other deposition sensi-tive machine parts, i.e. suction boxes in wire and pre66 section and with the polymer shower treatment.
The effect of the extended polymer shower treatment and the reduced biocide addition i8 shown in Table 1, No C.

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Claims

1. A method of controlling productivity disturbing micro-biological deposits on paper making equipment, characterized by applying to any locus or surface of said paper making equipment which locus or surface has a tendency of causing build-ups of such microbiological deposits, a deposition-controlling-amount of a deposition-controlling substance selected from the group consisting of water-soluble cationic polymers and cationic surfactants.

2. A method according to claim 1, characterized by applying said cationic polymer or cationic surfactant by spraying an aqueous solution thereof onto said locus or surface.

3. A method according to claim 2, characterized in that said aqueous solution is substantially free from anionic macro-molecules.

4. A method according to any one of the preceding claims, characterized in that the cationic polymer has a molecular weight within the range of 1,000 - 5,000,000, and/or that the cationic surfactant has a molecular weight of between about 200 and about 600.

5. A method according to claim 4, characterized in that the cationic polymer is selected from the group consisting of (a) dicyandiamide-formaldehyde condensation polymers, optionally including as polymerization reactant(s) at least one compound selected from the group consisting of formic acid and ammonium salts;
(b) polymers formed by reaction between epihalohydrins and at least one amine, and;
(c) polymers derived from ethylenically unsaturated monomers containing a quaternary ammonium group.

6. A method according to claim 5, characterized in that in polymer (b) the epihalohydrin is epichlorohydrin and/or the amine is selected from the group consisting of dimethylamine, diethylamine,methylethylamine,ethylenediamine,triethanolamine and a polyalkylene polyamine.

7. A method according to claim 6, characterized in that the polymer is represented by the general formula:

where A is a number within the range of 0-500.

8. A method according to claim 5, characterized in that polymer (c) comprises a homo- or copolymer of (i) a vinyl compound quaternized with a C1 - Cl8 alkyl halide or a benzyl halide or with dimethyl or diethyl sulphate, or a vinyl compound quaternized with a tertiary amine of the formula NR~R2R3, where R1, R2 and R3 are each and independently lower alkyl with the proviso that one of R1, R2 and R3 can be C1 -C18 - alkyl;
(ii) a quaternized allyl compound; or (iii) an acrylic derivative which may be quaternized with a C1 - C18 - alkyl halide, a benzyl halide or dimethyl or diethyl sulphate, a methacrylamido-propyl-tri(C1-C4-alkyl), (meth) acryloyloxyethyl-tri(C1-C4-alkyl), methosulphate, ethosulphate.

9. A method according to claim 8, characterized in that said copolymer is derived from a comonomer selected from the group oonsisting of a meth(acrylic) derivative, an acrylate- or methacrylate-(C1-C18)-alkyl ester or acrylonitrile, and an alkyl vinyl ether, vinyl pyrrolidone and vinyl acetate.

10. A method according to claim 9, characterized in that said copolymer contains 10-100 mole percent of recurring units of the formula X-and 0-90 mole percent of recurring units of the formula:

wherein R1 represents hydrogen or lower alkyl R2 represents a long chain alkyl group, R3 R4 and R5 each and independently represent hydrogen or lower alkyl, and X represents an anion, preferably a halide ion, a methosulphate ion, and ethosulphate ion.

11. A method according to claim 5, characterized in that polymer (c) comprises a homo- or copolymer of diallyldimethyl ammonium chloride having recurring units of the formula:

where Z represents monomeric units;

m is within the range of 5-100%; and n is within the range of 0-95%.

12. A method according to claim 5, characterized in that polymer (c) is derived from monomers of the general formula:

where Z and Z', which may be the same or different, are -CH2CH=CHCH2- or -CH2-CHOHCH2-, Y and Y', which may be the same or different, are X or -NR'R", X is a halogen having an atomic weight greater than 30, n is an integer of from 2 to 20, and R' and R"
(i) may be the same or different alkyl groups of from 1 to 18 carbon atoms, optionally substituted by 1 to 2 hydroxyl groups; or (ii) when taken together with N represent a saturated or unsaturated ring of from 5 to 7 atoms; or (iii) when taken together with N and an oxygen atom represent the N-morpholino group.

13. A method according to claim 5, characterized in that polymer (c) of the formula:
is derived from polybutadienes which have been reacted with a lower alkyl amine and where some of the resulting dialkyl amino groups have been quaternized and which polymer comprises recurring units of the formulae:

F) G) H) and I)

14. A method according to claim 13, characterized in that the quaternizing agent comprises methyl chloride, dimethyl sulphate or diethyl sulphate and/or (b+c) is from 10 to 90% and (a+d) is from 90 to 100%.

15. A method according to any one of claims 1 to 3 and 5 to 14, characterized in that the molecular weight of the cationic polymer is from about 20,000 to 300,000.

16. A method according to claim 4, characterized in that the molecular weight of the cationic polymer is from about 20,000 to 300,000.

17. A method according to any one of claims 1 to 3 and 5 to 14, characterized in that the molecular weight of the cationic polymer is from about 10,000 to 50,000.

18. A method according to claim 4, characterized in that the molecular weight of the cationic polymer is from about 10,000 to 50,000.

19. A method according to any one of claims 1 to 4, characterized in that the cationic surfactant is of the general formula:
X-wherein each R is independently selected from the group consisting of hydrogen, alkyl groups having between about 1 and 22 carbon atoms, aryl groups, and aralkyl groups, at least one of said R groups being an alkyl group having at least about 8 carbon atoms; and wherein X is an anion.

20. A method according to claim 19, characterized in that two of the R groups are selected from the group consisting of methyl and ethyl.

21. A method according to claim 19, characterized in that one R group is Ph-CH2- or Ph-CH2-CH2- where Ph is phenyl.

22. A method according to claim 20, characterized in that one R group is Ph-CH2- or Ph-CH2-CH2- where Ph is phenyl.

23. A method according to claim 19, characterized in that said surfactant comprises alkyldimethylbenzyl ammonium chloride(s) having alkyl group(s) of between about 12 and 16 carbon atoms.

24. A method according to claim 20, 21 or 22, characterized in that said surfactant comprises alkyldimethylbenzyl ammonium chloride(s) having alkyl group(s) of between about 12 and 16 carbon atoms.

25. A method according to any one of claims 1 to 3, 5 to 14, 16, 18, 20 to 23, characterized by applying said polymer or surfactant in an amount of at least about 5 parts per million of dilution water in a continuous treatment operation.

26. A method according to claim 4, characterized by applying said polymer or surfactant in an amount of at least about 5 parts per million of dilution water in a continuous treatment operation.

27. A method according to claim 15, characterized by applying said polymer or surfactant in an amount of at least about 5 parts per million of dilution water in a continuous treatment operation.

28. A method according to claim 17, characterized by applying said polymer or surfactant in an amount of at least about 5 parts per million of dilution water in a continuous treatment operation.

29. A method according to claim 19, characterized by applying said polymer or surfactant in an amount of at least about 5 parts per million of dilution water in a continuous treatment operation.

30. A method according to claim 24, characterized by applying said polymer or surfactant in an amount of at least about 5 parts per million of dilution water in a continuous treatment operation.

31. A method according to any one of claims 1 to 3, 5 to 14, 16, 18 or 20 to 23, characterized by applying said polymer or surfactant in an amount of at least about 50 parts per million of dilution water in an intermittent treatment operation.

32. A method according to claim 4, characterized by applying said polymer or surfactant in an amount of at least about 50 parts per million of dilution water in an intermittent treatment operation.

33. A method according to claim 15, characterized by applying said polymer or surfactant in an amount of at least about 50 parts per million of dilution water in an intermittent treatment operation.

34. A method according to claim 17, characterized by applying said polymer or surfactant in an amount of at least about 50 parts per million of dilution water in an intermittent treatment operation.

35. A method according to claim 19, characterized by applying said polymer or surfactant in an amount of at least about 50 parts per million of dilution water in an intermittent treatment operation.

36. A method according to claim 24, characterized by applying said polymer or surfactant in an amount of at least about 50 parts per million of dilution water in an intermittent treatment operation.

37. A method according to any one of claims 1 to 3, 5 to 14, 16, 18, 20 to 23, 26 to 30 or 32 to 36, characterized by applying said cationic polymer or surfactant in an amount of up to 500 parts per million of dilution water.

38. A method according to claim 4, characterized by applying said cationic polymer or surfactant in an amount of up to 500 parts per million of dilution water.

39. A method according to claim 15, characterized by applying said cationic polymer or surfactant in an amount of up to 500 parts per million of dilution water.

40. A method according to claim 17, characterized by applying said cationic polymer or surfactant in an amount of up to 500 parts per million of dilution water.

41. A method according to claim 19, characterized by applying said cationic polymer or surfactant in an amount of up to 500 parts per million of dilution water.

42. A method according to claim 24, characterized by applying said cationic polymer or surfactant in an amount of up to 500 parts per million of dilution water.

43. A method according to claim 25, characterized by applying said cationic polymer or surfactant in an amount of up to 500 parts per million of dilution water.

44. A method according to claim 31, characterized by applying said cationic polymer or surfactant in an amount of up to 500 parts per million of dilution water.

45. A method according to any of claims 1 to 3, 5 to 14, 16, 18, 20 to 23, 26 to 30, 32 to 36 or 38 to 44, characterized in that the charge density of the cationic polymer or surfactant is within the range of about 0.5 - 20 millie equivalent/gram.

46. A method according to claim 4, characterized in that the charge density of the cationic polymer or surfactant is within the range of about 0.5 - 2.0 millie equivalent/gram.

47. A method according to claim 15, characterized in that the charge density of the cationic polymer or surfactant is within the range of about 0.5 - 2.0 millie equivalent/gram.

48. A method according to claim 17, characterized in that the charge density of the cationic polymer or surfactant is within the range of about 0.5 - 2.0 millie equivalent/gram.

49. A method according to claim 19, characterized in that the charge density of the cationic polymer or surfactant is within the range of about 0.5 - 2.0 millie equivalent/gram.

50. A method according to claim 24, characterized in that the charge density of the cationic polymer or surfactant is within the range of about 0.5 - 2.0 millie equivalent/gram.

51. A method according to claim 25, characterized in that the charge density of the cationic polymer or surfactant is within the range of about 0.5 - 2.0 millie equivalent/gram.

52. A method according to claim 31, characterized in that the charge density of the cationic polymer or surfactant is within the range of about 0.5 - 2.0 millie equivalent/gram.

53. A method according to claim 37, characterized in that the charge density of the cationic polymer or surfactant is within the range of about 0.5 - 2.0 millie equivalent/gram.

54. A method of claim 4 wherein the cationic polymer has a molecular weight within the range of about 10,000 and about 300,000.

55. A method of claim 10 wherein Z represents monomeric units from a (meth) acrylic derivative.

56. A method of claim 55 wherein Z represents monomeric units from a (meth) acrylic derivative selected from the group comprising acrylamide, an acrylate- or methacrylate-(C1-C18)-alkylester or acrylonitrile.

57. A method of claim 10 wherein R2 represents a long chain allyl group with 8-18 carbon atoms.