NO175402B - Procedure for preventing microbiological deposits in papermaking equipment - Google Patents

Description

The present invention relates to an improved method for obtaining clean sheet forming equipment and the like for papermaking, and more particularly for chemical treatment of papermaking equipment to control or regulate productivity-disrupting deposits of microbiological material thereon, as stated in claim 1's preamble.

The manufacture of paper typically involves the processing of a carefully prepared water-based fiber suspension to obtain a predominantly homogeneous dry sheet of paper. Three steps involved in this typical process are sheet forming, where the suspension is passed over a porous cloth or "wire", onto which fibers are deposited by filtering the liquid through the wire, sheet pressing, where the formed sheet passes through presses lined with porous "felt" for extraction of the residual water content from the sheet to improve the homogeneity of the sheet and to give the sheet surface quality, and paper drying, where the remaining water is driven off the sheet. The sheet can then be processed further into the finished paper product.

It is well known that draining water is an energy-intensive operation and thus relatively expensive. Consequently, an efficient papermaking operation depends on extracting water during the forming and pressing operation and on avoiding sheet defects, which render the dried sheet unsuitable for use. Felt and wire are therefore particularly important, as they affect not only water excretion but also, depending on their intimate contact with the sheet, the quality of the sheet itself. Deposits collected on the wire affect the efficiency with regard to separated water and can be transferred to the sheet material and thereby give rise to defects.

The quality of the water-based fiber suspension used for the production of the sheet depends on many factors, including the wood and water used as raw materials, the composition of any recycled material added to the process and the additives used in the production of the suspension. In this way, a number of dissolved or suspended materials can be introduced into the manufacturing process, including inorganic materials such as e.g. salts and clay, which materials are of an organic nature such as resins or pitch from the tree and also printing inks, latex and binders from recycled paper products, A build-up of deposits containing inorganic and/or organic material on felt and other sheet forming equipment during the manufacturing process is a well-known difficult problem in connection with efficient paper production.

Another particularly difficult deposit is the slime-like gelatinous material produced by certain bacteria that occur naturally in the papermaking system. (This material will hereafter be referred to as "slime"). As the conditions in a paper machine system are very favorable for the growth of bacteria, the problem of slime deposits on paper machine parts often becomes difficult, and if they are not removed, they will lead to serious production disturbances in the paper-making process.

Methods for the fast and efficient removal of slime deposits from the paper machine equipment are of great importance to the industry. The paper machines can be shut down for cleaning, but such interruptions for cleaning are not desirable because of the resulting production losses. So-called on-line treatment is therefore strongly preferred if this can be carried out in an efficient manner.

The most common and successful way to remove slime from paper machine equipment has been to treat the water-based fiber suspension with various types of biocides. Examples of such biocides are methylene bis-thiocyanate, 5-chloro-2-methyl-4-isothiazolin-3-one and 2-methyl-4-isothiazolin-3-one.

However, chemicals of this type are often very unpleasant to handle, and are often regarded from an environmental and health and safety point of view as unpleasant or objectionable. Because of this, there are strong forces within the industry to avoid the use of biocides in the papermaking process wherever possible.

Another way of trying to solve the problem of slime control has been to combine biocide treatment of the fiber suspension with the addition of anionic dispersants. However, progress in connection with this attempt at a solution has been very limited, especially in paper systems that work with a high degree of closed backwater system.

Yet another way of trying to achieve mucus regulation has been to treat the fiber suspension with enzymes. However, commercial progress with this method has also been very limited.

Based on this, it is easy to realize that a method which enables an effective regulation of slime deposits on paper machines, without the disadvantages associated with biocides, would be a significant step forward towards a more environmentally acceptable papermaking process.

It is now surprisingly found that productivity problems

caused by deposits of organic matter originating from microbiological activity, can be controlled or regulated in an effective manner without the use of toxic biocides or reduced amounts of such toxic biocides, namely by the use of certain polymers or surface-active compounds without mixing the substances in question into the pulp. The relevant polymers or surface-active substances are previously known in and of themselves, but as far as is known, they have never been used or proposed for use in the way that is done in the present invention. In accordance with this and in connection with prior art, reference is made to the following prior art: CA 365778, EP 8240026.1, US 3582461 and US 4190491, which all relate to resin regulation in connection with paper production, US 1486396 and US 4140798, which both relate to chemical substances such as in and for

previously known to inhibit the growth of microorganisms, and GB 2186895 which describes a group of chemicals which can be used in connection with the present invention, but which are not proposed for such use therein.

According to the present invention, it has therefore surprisingly been shown that certain cationic polymers or cationic surface-active compounds or mixtures can be used in an effective manner, without any toxic biocides or in combination with such biocides in a greatly reduced amount, to control or regulate deposition in connection with paper production of production-disrupting microbiological deposits, whereby the aforementioned cationic polymers or surface-active compounds are used in a new way.

One purpose of the invention is therefore to produce an improved process for paper production, where deposits of organic material of the aforementioned type are controlled, i.e. prevented or inhibited completely or at least to a very large extent, if the deposits in question have not already formed, or is reduced or dispersed completely or to a very large extent if the deposits have already formed. The invention is particularly interesting in connection with the regulation of mucus caused by mucus-forming microorganisms.

Another purpose of the invention is to produce a new method, with which the use of toxic biocides is eliminated or greatly reduced, i.e. to produce a method by deposit regulation for paper use, which method is acceptable from an environmental point of view.

Yet another purpose of the invention is to produce a method in which mixing of chemicals into the paper pulp is avoided or reduced.

Another purpose is to produce a method where very reduced concentrations of chemicals are used to regulate or control the aforementioned deposition problems.

Another purpose is to produce a method in which productivity and product quality in connection with paper production are improved.

A further purpose of the invention is to produce

a high quality paper produced by the method according to the invention.

The invention is thus characterized by what is stated in the characterizing part of claim 1, further features appear in claims 2-19.

According to the invention, the above purposes and other purposes are achieved by producing a method for regulating production-disrupting microbiological deposits on equipment for papermaking, where the method is characterized by the fact that at one place or another surface on said equipment for papermaking, a deposit-regulating amount of a deposition regulating substance selected from the group consisting of cationic polymers and cationic surface-active compounds, which includes mixtures thereof.

As mentioned above, the expressions "regulation", "control" or the like should be seen in connection with the invention. In other words, according to the invention, it has been shown that the cationic polymer or the cationic surface-active compounds or a mixture thereof can be used both to prevent or inhibit the formation of deposits and to dissolve or disperse deposits that have already formed.

As regards the meaning of the expression "some place or surface of the papermaking equipment which is sensitive to the build-up of such deposits" or the like, it may be added that the general meaning thereof is that the cationic polymer or the cationic surface-active compounds are not mixed into pulp or the paper, but is applied to a strategic part or position on the papermaking equipment. In this way, a person skilled in the field knows from experience which place or which surface shows the greatest tendency to form deposits, i.e. where the cationic polymer or the cationic surface-active compound should primarily be applied in order to obtain the best possible result. Naturally, this also means that the polymer or the surface-active compound can be applied to more than one such place or surface, if this is necessary or appropriate.

The invention can generally be applied to any water-soluble cationic polymer or water-soluble surface-active compounds of the aforementioned type, which primarily means that a water-based solution of this polymer or this surface-active compound is used. This in turn implies that a particularly preferred method for applying the cationic polymer or the cationic surface-active compound to said place or surface is with a spray or spray operation, as this is usually a simple operation and as such operations have been shown to be very effective in connection with the invention. In other words, it has surprisingly been shown that very low concentrations of the polymer can be used in this way to obtain an extraordinary result.

The method according to the invention can usually be applied to the regulation of any deposit caused by microorganisms, but it has proven to be particularly interesting for the regulation of deposits caused by bacteria, e.g. mucus caused by mucus-forming bacteria.

Since the most distinct feature of the invention is the application of the cationic polymer or the cationic surface-active compounds directly to the place or the surface to be treated, whereby said polymer or surface-active compound is used in surprisingly low concentrations, the exact type of that polymer or surface-active compound is the compound used is not the most important feature of the invention. In this way, a variety of different polymers and surfactants can be used within the scope of the invention, i.e. also based on previously known microbiocidal activities. However, a number of particularly preferred polymers and surface-active compounds will be discussed later. Typically, a water-soluble polymer or surface-active compound is used.

According to the preferred embodiment, a cationic polymer is thus used which has a molecular weight in the range 1,000 - 5,000,000 f-eg. in the range 10,000 - 300,000. A preferred embodiment within these ranges is 20,000 - 300,000, especially 20,000 - 50,000. Another preferred range is 10,000 - 50,000.

A preferred range for the molecular weight of the cationic surface-active compound is between 200 and 600. According to another preferred embodiment of the invention, a water-based solution of the polymer or the surface-active compound is used, which solution is substantially free of anionic macromolecules.

The charge density of the compound used according to the invention should lie within a range of from 0.5 milliequivalents/gram to 20 milliequivalents/gram. A preferred embodiment within this range is 1-10 milliequivalents/gram, and especially 2-8 milliequivalents/gram.

A preferred group of cationic polymers according to the invention comprises dicyandiamide-formaldehyde condensation polymers. Polymers of this type are described by many patents: US 2774749, US 2829126, GB 1193294, DE 917392, FR 1484381, DE 2017114. JP 75111864, JP 7316067, DE 2515175, CH application 9527/72, DE OS 24571698, DE OS 24571698, DE 2403443, FR 1414407 and DE 2321627 represent some examples of such.

Another preferred group of cationic polymers for use according to the invention are the polymers which are formed by reaction between epihalohydrins and various amines. The most preferred epihalohydrins in this respect are epichlorohydrin, and examples of suitable amines include dimethylamine, diethylamine, methylethylamine, ethenediamine, triethanolamine and a polyalkene polyamine. Examples of such include the polymers obtained by reaction between a polyalkene-polyamine and epichlorohydrin, as well as the polymers obtained by reaction between epichlorohydrin, dimethylamine and either ethylenediamine or a polyalkene-polyamine. A typical amine that can be used is N,N,N',N'-tetramethyl-ethenediamine and ethenediamine used together with dimethylamine and tri-ethanolamine. Polymers of this type include those polymers that have the following general formula:

where A is a number in the range 0 - 500.

Preferred cationic polymers according to the invention also include those obtained by reacting dimethylamine, diethylamine or methylethylamine, preferably either dimethylamine or diethylamine, with an epihalohydrin, preferably epichlorohydrin. Polymers of this type are described in US 3738945 and Canadian patent 1096070, where the contents of both these patents are hereby incorporated into the present text. Such polymers are commercially available as Agefloc A50, Agefloc A-50HV and Agefloc B-50 from CPS Chemical Company, Inc., New Jersey, USA. These three products are stated to contain as their active ingredients 50% by mass of polymers with molecular weights of 75,000 - 80,000, 200,000 - 250,000 and 20,000 - 30,000 respectively. Another commercially available product of this type is Magnifloc 573C from American Cyanamid Co., New Jersey, USA, and which is believed to contain as its active ingredient 50% by mass of a polymer with a molecular weight of 20,000 - 30,000.

Another preferred group of cationic polymers for use according to the invention comprises polymers of ethylenically unsaturated monomers, containing a quaternary ammonium group. Such polymers may include homo- and copolymers of vinyl compounds, such as vinylpyridine and vinylimidazole, which may be quaternized with e.g. a C 1 - C 18 alkyl halide, a benzyl halide, especially a chloride, or dimethyl or diethyl sulfate or vinyl benzyl chloride, which may be quaternized with e.g. a tertiary amine with the formula NR1R2R3, where R1/R2°9 R3 nve*"°9 independently of each other is lower alkyl, preferably with 1-4 carbon atoms, with the proviso that one of these groups Rlf R2 and R3 can be - C18 alkyl . (i~C4 alkyl, especially methyl)-ammonium salt or a (meth)acryloyloxyethyl-tri-(C-^- C^, especially methyl)-ammonium salt, whereby said salt is a halide, especially a chloride, methosulfate, ethosulfate or l /n of an n-valent anion. ;In this context it should also be added that "lower alkyl" expressed in the description and patent claims means an alkyl group containing 1-6 carbon atoms, unless otherwise stated. ;In the aforementioned case of copolymers can the monomers are copolymerized, for example, with a (meth)acrylic derivative, such as acrylamide, a acrylate or methacrylate C₁-C₂ alkyl ester or acrylonitrile, or alkyl vinyl ester, vinyl pyrrolidone or vinyl acetate. Typical such polymers contain from 10 to 100 mol-% repeating units of the formula: and 0-90 mol-% repeating units of the formula: ;where R 1 represents hydrogen or lower alkyl, preferably alkyl of 1-4 carbon atoms, R 2 represents a long-chain alkyl group , typically having from 8-18 carbon atoms, R3, R4 and R5 each and independently represent hydrogen or lower alkyl, while X represents an anion, typically a halide ion, a methosulfation, an ethosulfation or l/n of an n-valent ion . ;Other quaternary ammonium polymers derived from an unsaturated polymer include homo- and copolymers of diallyl-dimethyl-ammonium chloride, which contain repeating units of the formula : ;where Z represents monomeric units, such as a (meth)-acryl derivative, such as an acrylamide, an acrylate or methacrylate C 1 -C 18 alkyl ester or acrylonitrile, or an alkyl vinyl ether, vinyl pyrrolidone or vinyl acetate, m is in the range 5 - 100% and n is in the range 0 - 95%. In this connection, it should be mentioned that this polymer should be considered "essentially linear" since, despite the presence of cyclic groups, these groups are connected along a linear chain and no crosslinks occur. ;Other polymers which can be used and which are prepared from unsaturated monomers include those with the formula: ;where Z and Z<1> which may be the same or different, are -CH2CH=CHCH2-or CH2-CHOHCH2-, Y and Y<1 > are the same or different, is either X or -NR"R", X is a halogen with a higher atomic mass than 30, n ;is an integer from 2 to 20, and R<*> and R" (i) can be the same or different alkyl groups with 2-18 carbon atoms, optionally substituted with 1-2 hydroxyl groups, or (ii) when they

considered together with N, represents a saturated or unsaturated ring of 5-7 carbon atoms, or (iii) when considered together with N and an oxygen atom, represents the N-morpholine group, especially poly(dimethyl-butenyl)ammonium chloride-bis-(triethanol- ammonium chloride).

Another class of polymers which may be used and which are prepared from ethylenically unsaturated monomers include polybutadienes, which are reacted with a lower alkyl group and in which certain of the resulting dialkylamino groups are quaternized. Usually the polymer therefore contains repeating units of the formula:

in the molar ratio a:b:c:d respectively, where R represents a lower alkyl radical, typically a methyl or ethyl radical. It can be added that the lower alkyl radicals do not have to be the same. Typical quaternizing agents include methyl chloride, dimethyl sulfate, and diethyl sulfate. Varying ratios a:b:c:d can be used, whereby the amine amounts (b+c) are usually 10 - 90% and (a+d) are 90 to 10%. These polymers are obtained by reacting polybutadiene with carbon monoxide and hydrogen in the presence of a suitable lower alkylamine.

Other cationic polymers, which have the property that they can interact with anionic macromolecules and/or slimy material in a pulp for paper production, can also be used within the scope of the present invention. These may include cationic tannin derivatives, such as those obtained via a Mannich-type reaction of tannin (a condensed polyphenolic core) with formaldehyde and an amine, formed as a salt e.g. acetate, formate, hydrochloride or quaternized as well as polyamine polymers, which are cross-linked, such as polyamideamine/polyethylene-polyamine polymers cross-linked with e.g. epichlorohydrin. Yet another suitable type of polymers are those obtained by reacting a polyamidoamine with epichlorohydrin. Such cross-linked polyamidoamines are described in US 3250664, 3893885, 3642572 and 4250299, which are hereby included in the present text.

According to a preferred embodiment of the invention, the surface-active compound has the general formula:

where each group R is independently selected from the group consisting of hydrogen, alkyl groups with 1-22 carbon atoms, aryl groups and aralkyl groups, whereby at least one of these R groups is an alkyl group with at least 8 carbon atoms, and preferably an n-alkyl group with 12 - 16 carbon atoms, and each X~ is an anion, preferably a halide ion, e.g. chloride, or l/n of an n-valent anion. Mixtures of these compounds can also be used as surface-active compounds according to the invention.

Preferably, two of the R groups of the surface-active compound are selected from the group consisting of methyl and ethyl, most preferably methyl. Preferably, an R group is also selected from among the aralkyl groups Ph-CH2- and Ph-CH2-CH2-, where Ph is phenyl. The most preferred aralkyl group is benzyl.

Thus, particularly useful surfactant compounds include alkyl-dimethyl-benzyl-ammonium chlorides with alkyl groups of 12-16 carbon atoms. A commercially available product of this type comprises a mixture of alkyl-dimethylbenzylammonium chlorides, where 50% of the surfactant has a C14H29-n-alkyl group, 40% of the surfactant has a Ci2<H>25~<n> ~alky19ruPPe 0<? 10% of the substance has a C₁gr₂-n-alkyl group. This product is already known in itself for its microbiocidal effect.

As mentioned above, it has been shown that when the cationic polymers and/or cationic surfactant compounds according to the invention are applied directly, preferably by spraying, on paper machine parts in low concentrations, slime and other microbiological deposits on parts or equipment will be reduced or eliminated significantly. More specifically, it has been shown that usually such a low concentration of the polymer or surfactant as from 0.1 ppm in the dilution water produces a deposit-reducing effect. Preferably, this amount is from 5 ppm of the dilution water when continuous treatment is used, and preferably from 50 ppm of the dilution water when the application takes place intermittently. Regarding the upper limit, this can easily be determined by a person skilled in the art in each individual case, but generally speaking, this amount or concentration is kept as low as possible to avoid unnecessary contamination of the paper thereby. A preferred upper limit is 500 ppm of the dilution water.

Although the mechanism for the phenomenon obtained by the invention is not entirely certain, it is assumed that the cationic components according to the invention disperse the mucus in an embryo stage, which thus prevents the build-up of large lumps. The returned dispersed slime can then be easily removed from the system together with the paper sheet. In all cases

the slime's tendency to pass through the papermaking equipment, instead of the slime sticking to it, is significantly increased by treatment according to the invention.

As previously described, the polymer or surface-active compound is applied, e.g. by spraying in water-based

solution directly on the equipment to be treated.

As also previously mentioned, the water solution containing the cationic polymer and/or the surface-active compound should be substantially free of anionic macromolecules. This anionic material includes natural materials such as wood lignins, byproducts of chemical pulping, such as sodium lignosulfonate, and synthetic materials such as polyacrylates.

The polymers and the surface-active compounds according to the invention are typically supplied in the form of liquid mixtures, comprising water-based solutions of the polymer and/or the surface-active compound. The polymer concentration of the mixtures may vary from such dilute solutions as to have a polymer concentration suitable for continuous application up to the solubility or gelation limit of the polymer, but usually the mixtures are relatively concentrated for practical transport and handling. In addition, the liquid mixtures can include additional material, which improves the dissolution of the polymers, whereby more concentrated mixtures can be obtained. As an example of such materials, reference is made to alkoxyethanols, such as butoxyethanol. Suitable water-based mixtures usually contain 5-50% by mass of the cationic products according to the invention. It should also be added that, if desired, the mixtures according to the invention can be added in solid form, e.g. in the form of granules.

The most appropriate treatment dose or dosage is

depending on such system factors as the level of soiling of the adhesive material and whether the cleaning is continuous or periodic. Even liquid mixtures with relatively high concentrations of a polymer according to the invention (e.g. 50%), can be used at full strength (100% as a liquid mixture), e.g. in that the diluted liquid mixture is sprayed directly onto the machine parts. Especially where continuous treatment is carried out, however, the mixtures can be included

benefit is washed out at the treatment site with clean fresh water or another water-based liquid. Where it is necessary for economic reasons with respect to the water, the process water may be sufficient or suitable for dilution.

In general, the method can be carried out continuously to regulate the deposits continuously. In certain cases, however, it is not practical to have a continuous treatment, and in such cases the treatment with the cationic polymers and the surface-active substances according to the invention can take place periodically. For example, water-based solutions of the polymer or the surface-active substance can be sprayed onto the coated surface, until this surface is sufficiently clean and the spraying can then be stopped until a repeat treatment is necessary.

The invention will now be further described with the following non-limiting example.

EXAMPLE.

A commercial paper machine of the double-wire type was used to produce newsprint. In order to inhibit microbiological growth and the corresponding occurrence of slime deposits, biocides were added to the backwater circulation system of this machine.

The addition points for the biocides are locked to the wire tub and the shower water tank. Furthermore, a cationic polymer of the dicyandiamide-formaldehyde type was used as a deposit control agent, and as such the fiber suspension was added in a position corresponding to the suction side of the Deculator pump. The complete dosing situation and machine capacity status is shown in Table 1 No. A.

In the first experiment, the point of addition of the polymer was moved from the pulp suspension to the water used for the high-pressure shower system, which enabled the diluted cationic polymer to directly, via the high-pressure spray tubes, come into contact with machine parts sensitive to slime deposits . The actual surfaces connected to the high-pressure shower system are the top and bottom wire, the forming roller, the collection felt and the press filters. The effect of the new treatment on the machine is shown in table 1 no. B.

In the second attempt, two things were done. Firstly, the addition of biocide to the shower water tank was discontinued. Secondly, the polymer shower treatment was extended to also include the low-pressure shower system. Compared to the first attempt, with this extension it was also possible to reach other deposit-sensitive machine parts, i.e. suction vessels in the wire and press section and with the polymer shower treatment.

The effect of the extended polymer shower treatment and the reduced biocide addition is shown in Table 1 no. C.

Claims (20)

1. Procedure for regulating production-disrupting microbiological deposits, e.g. slime, on papermaking equipment, characterized in that in the areas of the papermaking equipment where such microbiological deposits are formed, a deposit-regulating amount of cationic polymers or cationic surface-active compounds is applied, the cationic polymer being selected from the group consisting of a) dicyandiamide-formaldehyde condensation polymers, optionally containing as polymerization reactant(s) at least one compound selected from the group consisting of formic acid and ammonium salts, preferably ammonium chloride, b) polymers of the general formula where A is a number in the range 0 - 500, and obtained by reacting epihalohydrins and at least one amine, and c) polymers obtained from ethylenically unsaturated monomers containing a quaternary ammonium group, and where the cationic surface-active compound has the general formula: where each R is independently selected from the group consisting of hydrogen, alkyl groups with 1-22 carbon atoms, aryl groups and aralkyl groups, whereby at least one of said R groups is an alkyl group with at least 8 carbon atoms and preferably an n-alkyl group with 12 - 16 carbon atoms, and each X~ is an anion, preferably a halogen, e.g. chloride, or l/n of an n-valent anion. 2. Method according to claim 1, characterized in that the cationic polymer or cationic surface-active compound is applied by spraying a water-based solution thereof on said area. 3. Method according to claim 2, characterized in that the water-based solution is substantially free of anionic macromolecules. 4. Method according to claims 1 - 3, characterized in that the cationic polymer has a molecular weight in the range 1,000 - 5,000,000, especially in the range 10,000 - 300,000 and/or that the cationic surface-active compound has a molecular weight of 200 -600. 5. Method according to claim 1, characterized in that polymer (c) comprises a homo- or copolymer of i) a vinyl compound, e.g. vinylpyridine or vinylimidazole, quaternized with a C 2 -C 3 -alkyl halide or a benzyl halide, preferably the chloride, or with dimethyl or diethyl sulfate, or a vinyl compound, e.g. vinylbenzyl chloride, quaternized with a tertiary amine of the formula NR1R2R3, where R^ R2 and R3 are each and independently lower alkyl, preferably with 1-4 carbon atoms, with the proviso that one of R1# R2 and R3 may be C^ - C^ q alkyl, ii) an alkyl compound, e.g. diallyl-dimethyl-ammonium chloride, or iii) an acrylic derivative, e.g. dialkylamino-methyl(meth)-acrylamide, which may be quaternized with a - C^_ q alkyl halide, a benzyl halide or dimethyl or diethyl sulfate, a methacrylamidopropyl-tri(Ci-C4~ alkyl, especially methyl) ammonium salt or a (meth)acryloyloxyethyl-tri(C1-C4-alkyl, especially methyl)-ammonium salt, preferably a halide, e.g. chloride, methosulfate, ethosulfate or l/n of an n-valent anion. 6. Method according to claim 5, characterized in that the copolymer is obtained from a comonomer selected from the group consisting of a meth(acrylic) derivative, e.g. an acrylamide, an acrylate or methacrylate (C 1 -C 2 ) alkyl ester or acrylonitrile and an alkyl vinyl ether, vinyl pyrrolidone and vinyl acetate. 7. Method according to claim 7, characterized in that the copolymer contains 10 - 100 mol-% repeating units with the formula: and 0-90 mol-% repeating units with the formula where R 1 represents hydrogen or lower alkyl, preferably with 14 carbon atoms, R 2 represents a long-chain alkyl group, preferably with 8-18 carbon atoms. R 3 , R 4 and R 5 each and independently of one another represent hydrogen or lower alkyl, and X represents an anion, preferably a halogen, a methosulfation, an ethosulfation or 1/n of an n-valent anion. 8. Method according to claim 1, characterized in that polymer (c) includes a homo- or copolymer of diallyl-dimethyl-ammonium chloride with repeating units of the formula: where Z represents monomeric units, preferably from a (meth)acrylic derivative, such as an acrylamide, an acrylate or methacrylate-(C^-C^g) alkyl ester or acrylonitrile, or an alkyl vinyl ether, vinyl pyrrolidone or vinyl acetate, m is in the range 5 - 100%, and n is in the range 0 - 95%. 9. Method according to claim 1, characterized in that polymer (c) is obtained from monomers with 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<1>R", X is halogen with an atomic mass greater than 30, n is an integer from 2 to 20, and R' and R" i) can be the same or different alkyl groups with 1-18 carbon atoms, optionally substituted with 1-2 hydroxyl groups, or ii) when they are considered together with N, represent a saturated or unsaturated ring of 5-7 carbon atoms, or iii) when considered together with N and an oxygen atom, represent the N-morpholine group, especially poly(dimethyl-butenyl)-ammonium chloride-bis-(triethanol) -ammonium chloride). 10. Process according to claim 1, characterized in that polymer (c) is obtained from polybutadienes, which are reacted with a lower alkylamine and where certain of the obtained dialkylamino groups are quaternized, in particular a polymer including repeating units with the formulas in the molar ratio a:b:c:d, where R represents lower alkyl, preferably methyl or ethyl. 11. Method according to claim 11, characterized in that the quaternization medium includes methyl chloride, dimethyl sulfate or diethyl sulfate and/or that (b+c) is 10 - 90% and (a+d) is 90 - 10%. 12. Method according to claims 1 - 12, characterized in that the molecular weight of the cationic polymer is 20,000 - 300,000, preferably 20,000 - 50,000. 13. Method according to claims 1 - 13, characterized in that the molecular weight of the cationic polymer is 10,000 - 50,000. 14. Method according to claim 1, characterized in that two of the R groups are selected from the group consisting of methyl and ethyl, preferably methyl. 15. Method according to claim 1 or 15, characterized in that an R group is Ph-CH2- or Ph-CH2-CH2-, where Ph is phenyl, preferably benzyl. 16. Method according to claims 1-16, characterized in that the surface-active compound includes alkyl-dimethyl-ammonium chloride(s) with alkyl group(s) with 12-16 carbon atoms. 17. Method according to claims 1-17, characterized in that the polymer or the surface-active compound is applied in an amount of at least 5 ppm of the dilution water in a continuous treatment operation. 18. Method according to claims 1-18, characterized in that the polymer or the surface-active compound is applied in an amount of 50 ppm of the dilution water in an intermittent treatment operation. 19. Method according to claims 1-19, characterized in that the cationic polymer or the surface-active compound is applied in an amount of up to 500 ppm of the dilution water. 20. Method according to claims 1 - 20, characterized in that the charge density of the cationic polymer or the cationic surface-active compound lies within the range 0.5 - 20 milliequivalents/gram, preferably 1 - 10 and most preferably 2-9 milliequivalents/gram.