FI92731B - Control of deposits on paper machine blankets and the like - Google Patents

Description

92731

Control of Deposits of Paper Machine Felt and Similar Parts This is a continuation of U.S. Patent 245,852, filed September 16, 1988.

This invention relates to the equipment used in papermaking to treat sheet felt and the like, and more particularly to the chemical treatment of paper mill felts and similar parts to control sticky deposits formed on their surface.

Papermaking typically involves processing a carefully prepared aqueous fiber suspension to produce a very uniform dry sheet of paper. The three steps involved in a typical process are sheet formation, in which the suspension is passed to a porous screen or "wire" on the surface of which the fibers settle and through which the liquid is at the same time filtered; a sheet pressing step in which the formed sheet passes through porous "felt" coated presses to remove residual water from the sheet, to improve the uniformity of the sheet and to provide a surface quality of the sheet; and a paper drying step in which the aqueous residue of the sheet is evaporated. The sheet can then be processed into a final paper product.

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Evaporation of water is known to require a lot of energy and is therefore relatively expensive. Efficient papermaking therefore involves removing water from the soil during the forming and pressing stages of the paper and avoiding sheet defects leading to the unusability of the dry sheet of paper. Blankets and wires are therefore particularly important, as they not only affect dewatering, but because they are in close contact with the sheet, 35 they also play an important role in the quality of the sheet itself. Deposits accumulated on the felt and wire can affect dewatering efficiency, cause holes in the sheet, and can migrate into the sheet material, forming defects.

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The quality of the aqueous fiber suspension used to make the sheet depends on many factors, including the wood material and water used as raw materials, the composition of the recyclable materials added to the process, and the additives used in the suspension preparation step. Thus, a number of dissolved or suspended substances may have been included in the manufacturing process, including both inorganic substances such as salts and clays, and substances of organic origin such as wood resins or "resins", and dyes, latexes and adhesives derived from recycled paper products. substances. The formation of deposits containing inorganic and / or organic substances on the surfaces of felts and other papermaking equipment during the manufacturing process has been found to be a difficult barrier to efficient papermaking. A particular problem is tacky substances such as adhesives, resins, and the like associated with recycled fibers.

Methods for quickly and efficiently removing deposits from paper mill sheet-forming equipment are very important to the industry. Paper machines could be stopped during cleaning, but downtime for cleaning is not desirable due to the resulting production losses. Purification during use is therefore highly desirable in cases where it can be effectively applied.

The wire belt or cylinder used to form the sheet rotates as a continuous belt during production. The contact portion of the sheet during the cycle begins at the point where the supply of fiber to the wire belt or cylinder begins, and continues to the point where the formed sheet is led away from the surface of the wire; and the return portion of the cycle returns the wire from the point where the formed sheet was removed to the pin-35 of the wire back to the point where the contact portion of the sheet begins. Cleaning during use is usually the case for wire belts, * · ♦ such as Fourdrinier wires.

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3,92731 during the return portion (i.e., when the wire is not in contact with the sheet being formed) by treating the return wire with a cleaning fluid (usually water); often by spray spraying the wire with liquid. In addition to showers, mechanical 5 surface cleaning can be used. The use of water jets, with or without mechanical accessories, has not been shown to be sufficient to prevent organic or inorganic deposits from forming on the wire, and additives have been used to provide more effective cleaning fluids. The predominantly fibrous and inorganic substances have been successfully removed using aqueous mixtures containing either acids or bases as well as other chemicals such as surfactants. In cases where organic deposits have been predominant, deposits have been removed with some success using organic solvents, including mixtures containing aromatic compounds with low flash points or chlorinated hydrocarbons. Some machines today use small porous fabric belts instead of traditional wires.

20 The paper mill blankets also generally rotate continuously like a belt between the sheet contacting step and the returning step. During the contacting step of the sheet, the water in the sheet is usually removed by means of a vacuum developed through presses and / or felt pores. A clean felt with relatively open fine *: 25 pores is particularly desirable for efficient papermaking, as this allows for efficient dewatering of the paper sheet. The felt cleaning method should remove both general and special inorganic and organic deposits, maintain the porosity of the felt, and treat the surface of the fabric 30 without chemical or physical effects on the substrate. Mechanical cleaning, usually in the form of a scraper, has been used to remove contaminants from the surface of the felt. However, cleaning fluids are also used to remove cumbersome organic and inorganic deposits. The fabric assemblies of several of the felts used in the 35 paper mills are sensitive to chemicals. Cleaning chemicals should be able to be removed '·' by easy rinsing. Most paper mills use 4,92731 for both continuous and intermittent cleaning. The chemicals used are organic solvents, often chlorinated hydrocarbons. Acid and base based systems are also used, but as more dilute solutions than in wire cleaning. Alkali metal hydroxides in the spring are generally not suitable for cleaning felts because they react with the fabric material.

Some well-functioning organic solvents have been found to be hazardous to health, e.g. carcinogenic, so 10 they require special care. Other solvent-based products can damage the plastic or rubber parts used in the papermaking step. One of our in-use felt treatments has been used for several years with some success and involves treating felt 15 with an aqueous solution of cationic surfactants such as alkyldimethylbenzylammonium chloride with an alkyl group of 0.2¾, C14H29- and C16H33-. a mixture of groups. However, experience has shown that certain sticky substances still tend to adhere to felts despite treatment with these pin-20 ta-active substances. Another method of treating felts that has been advocated in the past is to apply an aqueous solution containing cationic polymers to the felts. However, this type of treatment can lead to the accumulation of substances derived from the cationic polymers themselves.

Other sheeting equipment, such as thickeners, filters, screens, and rollers, can also become dirty. These process problems and treatments are generally similar to the felt-30 system, although certain aspects, such as maintaining porosity and avoiding chemical damage to the fabric, which are important in cleaning felts and certain other small-pore equipment components, may not be as critical to other equipment. 35

The amount of natural resin contained in wood varies depending on the species of wood. Certain species of pine, especially those containing more than 2% by weight of resin, are usually used only in small quantities due to the resin problems they cause. The papermaker's 5,92731 alum or sodium aluminate has traditionally been used to control natural resin deposits. These products are added to the entire pulp system assembly with the goal of keeping the resin in the fiber. Factors limiting the effectiveness of such a method include e.g. pH, corrosion tendency, paper sheet formation, and the need to control the interaction between other chemicals in the pulp system. Treatments that would allow the unrestricted use of these problematic pine species could have a significant economic significance for some pulp and paper producers.

The increasing use of recycled fiber has led to increasingly severe deposits of sticky substances during papermaking. Adhesives, resins, etc., present in second-class 15 recycled fibers, tend to adhere to different parts of the paper machine and be resistant to cleaning during use. Materials that adhere to the felt can significantly impair dewatering and paper formation. The result is holes in the product, and in extreme 20 cases, a sheet of paper breaks during the process. Frequent downtime may be necessary for solvent washing of the felts to remove particularly sticky substances associated with the recycled fiber. The advantages of paper recycling in this context are somewhat opposite, as they reduce the production capacity of paper machines.

Certain organic cleaning agents, which were often used in the past, have proven to be harmful to the environment. The development of non-environmentally friendly cleaning agents for the cleaning of organic deposits has therefore been identified as important. The compounds used * must not, of course, damage the blankets or other forming devices. Although certain substances have been found to work satisfactorily under certain conditions, there is still a need to control the deposits that occur during papermaking, especially when recycled fibers are used as a raw material.

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Deposits have been controlled by the use of bulking agents such as anionic arylsulfonic acid formaldehyde concentrates or cationic dicyandiamide formaldehyde concentrates. Additives can act, for example, as insulating agents, dispersants or surfactants. In particular, cationic dicyandiamide-formaldehyde diamoplast resins have been described as causing the resin (i.e., resinous substances) to adhere to the surface of the pulp fibers as discrete particles such that the resin particles are unevenly distributed on the surface of the fibers. This greatly reduces the amount of resin that accumulates in the paper machine without causing dark stains or spots on the paper product.

We have found that the accumulation of sticky substances from papermaking pulp in papermaking felts and other papermaking equipment used in the processing of pulp into sheets can be prevented by applying to the equipment an aqueous solution containing at least 2 ppm of cationic polymer, applying to the equipment an aqueous solution consisting of water-soluble nonionic and cationic surfactants, and in an amount such that the formation of deposits derived from the cationic polymer can be prevented. The aqueous solution containing the cationic polymer and the surfactant: * is preferably substantially free of anionic macromolecules. Preferred cationic polymers are protonated or quaternary ammonium polymers, such as those obtained from the reaction between epihalohydrins and dimethylamines or diethylamines. Preferred cationic surfactants are alkyl dimethyl benzyl ammonium chlorides having from about 12 to about 16 carbon atoms in the alkyl groups. The present invention is particularly useful in the treatment of paper pulp and the handling of notes and similar equipment used in sheets.

It is an object of the present invention to provide a process by which material deposits present in papermaking equipment can be effectively controlled.

Another object of the present invention is to provide a process for controlling deposits in a paper mill which brings efficiency to papermaking using recycled fibers or resinous pine pulp fibers.

It is a further object of the present invention to provide a process for controlling deposits in a paper mill which is acceptable from an environmental point of view.

It is a further object of the present invention to provide a means for improving the production capacity and product quality of papermaking processes.

These and other objects and advantages of the present invention are described in more detail below.

Figure 1 is a schematic side view of paper machine felts that may be processed in accordance with the present invention.

Figure 2 is a schematic side view of the felts of a cylinder paper machine 20 that may be processed in accordance with the present invention.

The present invention relates to the use of an aqueous solution containing certain water-soluble cationic polymers and certain water-soluble surfactants to prevent the formation of both organic and inorganic deposits in felts or other sheet-forming devices, especially in the small-pore components of such devices. The treatment, which contains a cationic polymer as well as a cationic surfactant, allows a surprisingly effective control of the deposits in the treated devices, and also in cases where the recycled fiber material forms a significant part of the pulp mixture used. The invention provides a particularly effective cleaning and care agent for paper machine felts.

35 The present invention is generally applicable to polymer precision. . in nature and a considerable number of different polymers may be used provided they are cationic. The use of polyethyl β 92731 lenimines is considered to be within the scope of this invention, as are the use of numerous other polymeric materials containing amino groups, such as those prepared according to U.S. Patents 3,250,664, 3,642,572, 3,893,885 or 4,250,299; but the use of protonated or quaternary ammonium polymers is preferred. These preferred polymers are polymers obtained from reactions between epihalohydrin and one or more amines and polymers derived from ethylenically unsaturated monomers containing quaternary ammonium groups. The cationic polymers of this invention also include dicyandiamide-formaldehyde concentrates. Polymers of this type are discussed in U.S. Patent 3,582,461, which is incorporated herein by reference in its entirety. Either formic acid or ammonium salts and most preferably both formic acid and ammonium chloride can also be used as starting materials for the polymerization. However, certain dicyandiamide-formaldehyde concentrates tend to accumulate on felts and the like despite the presence of a cationic surfactant. A polymer of the dicyandiamide-formaldehyde type is sold under the tradename Tinofix QF, manufactured by Ciba Geigy Chemical Ltd. of Ontario, Canada, and contains as active ingredient about 50% by weight of a polymer believed to have a molecular weight of between about 20,000 and 50,000. 25>: Among the quaternary ammonium polymers derived from epihalohydrins and various amines are those derived from epihalohydrin and from the reaction of at least one amine which may be diethylamine, ethylenediamine or polyalkylene polyamine. Triethanolamine can also be used in the reaction. Examples are polymers obtained from reactions between polyalkylene polyamine and epihalohydrin, as well as polymers obtained from reactions between epichlorohydrin, dimethylamine and either ethylenediamine or polyalkylene polyamine. A typical useful amine is N, N, N ', N'-tetramethylethylenediamine as well as ethylenediamine used in combination with dimethylamine and tri-ethanolamine. The formula of these types of polymers 9 92731 is as follows: / hoch2ch ^^ -ch3 ^ \

5 H0CH „CHo - N-CH-CH-CH - N-CH.-CH-CHr - [- NH-CH - V

2 2/2 2 + _ 2 2 2 1 \ / C1_ /

\ HOCH2CH2 Cl 'OH CH3 oh J

'L _A / 2 10 where A is between 0-500, but other amines can of course be used.

Preferred cationic polymers of this invention are also those obtained by reacting dimethylamine, diethylamine or methylethylamine, preferably either dimethylamine or diethylamine, with epihalohydrin, preferably epichlorohydrin. Polymers of this type are discussed in U.S. Patent 3,738,945 and Canadian Patent 1,096,070, which are incorporated herein by reference in their entirety. Such poly-20 mers are sold under the brand names Agefloc A-50, Agefloc-50HV and

Agefloc B-50 and are manufactured by CPS Chemical Co., Inc. of New Jersey, USA. The three products have been reported to contain as active ingredient about 50% by weight of polymers having a molecular weight between 75,000 and 80,000, about 25,000,000 and 250,000, and about 20,000 and 30,000 in each product.

Another commercially available product of this type is Magnifloc 573C, manufactured by the American Cyanamide Company of New Jersey, USA, which is believed to contain about 50% by weight of a polymer having a molecular weight of between 20,000 and 30,000 as the active ingredient.

Typical polymers useful in this invention and derived from ethylenically unsaturated monomers include homo- or copolymers of vinyl compounds such as vinylpyrididine and vinylimidazole, which can be quaternized with, for example, dimethyl-C 1-4 alkyl halide, benzyl halide, benzyl halide, - or diethyl sulphate, or vinyl 92731 benzyl chloride, which can be quaternized, for example, with a tertiary amine of the formula NR1R2R3, in which R R2 and R3 are each lower alkyl, typically containing 1 to 4 carbon atoms, so that one of R1, R2 and R3 can be C 1 -C 4 alkyl; allyl compounds such as diallyldimethylammonium chloride; or acrylic derivatives such as dialkylaminomethyl (meta) acrylamide, which can be quaternized with, for example, a C 1 -C 6 alkyl halide, benzyl halide or dimethyl or diethyl sulphate, methacrylamidopropyl-10 (C 1 -C 4 alkyl) acryloxy, especially methyl) ammonium salt With a (-C 1-4) alkyl, especially methyl) ammonium salt, said salt being a halide, in particular chloride, methosulphate, ethosulphate, or the 1 / n-anion of n-valent. These monomers can be copolymerized with a (meth) acrylic derivative such as acrylamide, acrylate or methacrylate C1-C18 alkyl ester or acrylonitrile or alkyl vinyl ether, vinyl pyrrolidone, or vinyl acetate. Such polymers generally contain from 10 to 100 mol% of repeating units of the following formula: R1 R3-ch2-c-25 C00 (CH2) 2N-X "R5 30 and 0-90 mol% of repeating units of the following formula: en -CH-C-C 20 R 25 wherein R is hydrogen or a lower alkyl radical containing »* typically 1-4 carbon atoms, R 2 is a long chain alkyl group, 92731 containing typically 8-18 carbon atoms, R 1, R 4 and R 1 is each hydrogen or lower alkyl group and X is an anion, typically a halide ion, a methosulfate ion / ethosulfate ion or a 1 / n anion of an n-valent anion.

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Other quaternary ammonium polymers derived from unsaturated monomers are homopolymers of diallyldimethylammonium chloride containing repeating units of the following formula: 10 -CH 2 "" CH CH 2 -

Ch2 ^ ^ 'CH2 15 CHf ^ ^ ^ CH3 In this context, it should be noted that this polymer should be treated as "substantially linear" because, although it contains cyclic groups, these cyclic groups are linked in a linear chain and there is no crosslinking in the polymer.

Other useful polymers derived from unsaturated monomers follow the following formula: - ~ + + Y - ZNR'R "- Z'NR'R" - ZY '30 · Ljf X "J n where Z and Z', which may be the same or different are -CH2CH = CHCH2- or -CH2CHOCHCH2-, Y and Y ', which may be the same or different, are either X or -NR'R ", X is halogen having an atomic weight greater than 30, n is an integer from 2 to 20, and R 'and R "(i) may be the same or different alkyl groups having 1 to 18 carbon atoms substituted with 1 to 12 92731 hydroxyl groups; or (ii) which together with the N atom form a saturated or unsaturated ring of 5 to 7 atoms; or (iii) which together with the N- and oxygen atom form an N-morpholino group. A particularly preferred such polymer is poly (dimethylbutenyl) ammonium chloride-bis- (triethanolammonium chloride).

Another useful polymer group derived from ethylenically unsaturated monomers consists of polybutadienes which have been reacted with lower alkylamines and some of the resulting dialkylamino groups have been quaternized. The polymer therefore generally consists of repeating units of the following formula: a) - (CH 2 -CH) -b) - (CH 2 -H) -c) - (CH 2 -CH) - and d) - (CH 2 -H) - - ch CH- d: H0 CH „I 2 1 2 1 2 CH- CH_ CH- 1 2 I 2 3 CH CH CH„ 2 +! 2 _ I 2 NR3 X NR2 in a molar ratio of ^ ^ bb ^ c where R is a lower alkyl radical, typically a methyl or ethyl radical It will be appreciated that not all lower alkyl radicals need to be the same Typical quaternizing agents are methyl chloride, di-methyl sulphate and diethyl sulphate. Various ratios of a: b ^; b2: > generally 10-90% and (a + c) about 90-10% These polymers are obtained by reacting polybutadiene with carbon monoxide and hydrogen in the presence of a suitable lower alkylamine.

Other cationic polymers that can affect anionic macromolecules and / or sticky substances in the papermaking pulp may also be used within the scope of this invention.

These are also considered to include cationic tannin derivatives, such as those of the Mannich type, obtained from the reaction between tannin (condensed polyphenolic...) And formaldehyde and amine, in salt form, e.g. acetate, formate, hydrogen chloride or quaternized. also crosslinked polyamine polymers such as epichlorohydrin crosslinked polyamideamine / polyethylene polyamine copolymers. Natural resins and starches modified by the inclusion of cationic groups are also considered useful.

The most useful polymers of this invention generally have a molecular weight of between about 2,000 and about 3,000,000, although polymers having a molecular weight of less than 2,000 and more than 3,000,000 can also be used with some success. The polymer used preferably has a molecular weight of at least about 10,000 and most preferably at least about 20,000. The polymer used preferably has a molecular weight of about 300,000 or less, and most preferably about 50,000 or less. The molecular weight of the polymers is most preferably between about 20,000 and 50,000. Mixtures of these polymers can also be used.

This invention is also generally applicable to the nature of nonionic and cationic surfactants, and a wide variety of surfactants may be used in conjunction with the polymeric component provided that they are water soluble. Suitable nonionic surfactants include ethylene oxide and hydrophobic molecules such as long chain fatty alcohols, long chain fatty acids, alkylphenols, polyethylene glycol, long chain fatty acid esters, polyhydric alcohols and partial fatty acids and their partial fatty acids. or condensation products between etherified long chain polyglycols. Combinations of these condensation products can also be used.

35 Cationic surfactants are generally preferred. Particularly suitable surfactants for use in this invention are water-soluble surfactants having molecular weights between about 200 and 800 and having the general formula: u 92731

X

wherein each R is independently selected from the group consisting of hydrogen, polyethylene groups, polypropylene oxide groups, alkyl groups having 1 to 22 carbon atoms, aryl groups and aralkyl groups, and at least one of said R groups contains at least 8 carbon atoms and preferably an n-alkyl group having 12 to 16 carbon atoms ; and wherein X is an anion, typically a halide ion 10 (e.g. chloride), or a 1 / n anion of an n-valent anion. Mixtures of these compounds can also be used as the surfactant of this invention.

The two R groups of cationic surfactants of the formula are preferably methyl or ethyl, most preferably methyl; and one R group is either an aralkyl group or <s> -CH 2 -CH 2 -, most preferably benzyl. Thus, particularly useful surfactants include alkyldimethylbenzylammonium chlorides having an alkyl group of about 20 to 16 carbon atoms. One commercially available product of this type contains a mixture of alkyldimethylbenzylammonium chloride in which about 50% of the surfactant consists of a ^ 14 ^ 29 n-alkyl group> about 40% of the surfactant consists of a 0 ^ 2 ^ 25 n-alkyl group and about 10% of the surface The active substance consists of an n-alkyl group. This product is known as a bactericide.

Surfactants useful in the present invention also include pseudocationic agents having a molecular weight of between about 1,000 and about 26,000 and having the general formula: wherein NR 1 R 2 R 2> wherein R 1 and R 2 are polyethers such as polyethylene oxide, polypropylene oxide or a combined chain of ethylene oxide and propylene oxide, and wherein R 1 is a polyether, an alkyl group or hydrogen. Examples of this type of surfactant are disclosed in U.S. Patent 2,979,528.

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We have found that when the cationic polymers of this invention are applied in combination with nonionic and / or cationic surfactants to felts, the felts can resist the formation of sticky deposits. The adhesion of sticky substances associated with the recycled fiber material can be controlled particularly effectively. The present invention is therefore particularly useful in papermaking systems in which the proportion of recycled fiber material is significant, at least about 10%. In addition, significant results have been obtained in systems where the recycled fiber material has accounted for at least 70% of the total fiber volume, and also in systems where 100% of the pulp fibers of the paper mill are derived from recycled fiber. The invention is also considered to be particularly useful for controlling resin detached from fibers, especially when using pine wood as a raw material (e.g. 5% or more) containing more than 2% by weight or more of resin.

Although this phenomenon is not fully known, it is well known that adhesives associated with recycled fiber material are generally hydrophobic, and it is believed that the products formed by the interaction of these hydrophobic substances with the cationic components of this invention are more soluble in water. Wet adhesives 25 can thus significantly lose their tendency to adhere. on the surface of the felt, making them easy to remove from the surface of the felt. It is also known that papermaking pulp contains colloidal substances and anionic macromolecules, including synthetic anionic macromolecules that may have been added as part of the papermaking process, as well as natural anionic polymers, resins, soaps, surfactants and organic acids. ) which have entered the process as "anionic waste". It is believed that the cationic components used in this invention can act on anionic macromolecules and colloidal particles to provide products that are easily removed from felts. In any case, the tendency of the adhesives to pass past the papermaking equipment instead of adhering to them is increased by the treatment according to the present invention 16 92731.

The cationic polymers and surfactants of this invention are applied as an aqueous solution directly to the equipment being treated. Treatment with the surfactant alone has not provided the same level of deposition control as can be achieved with the combinations of this invention. Overdosing the polymer on paper machine felts without a sufficient amount of surfactant, on the other hand, results in the formation of deposits from the polymer 10 itself, and in the case of felts this means reduced porosity, which in turn can reduce dewatering or production efficiency in other ways (e.g. by increasing tack). Thus, the dosage of the polymer and surfactant used in the treatment should generally be adjusted according to the specific requirements of the system being treated. The aqueous solution containing the cationic polymer and the surfactant should preferably be substantially free of anionic macromolecules. These anionic materials are natural materials such as wood lignins, chemical pulping by-products such as sodium lignosulfonates, and synthetic materials such as polyacrylates.

The polymers and surfactants of this invention are generally liquid mixtures consisting of aqueous solutions of the polymer and / or surfactant. The polymer contents of the blends can range from relatively dilute solutions with polymer concentrations suitable for continuous use, up to the solubility or coagulation limit of the polymer, but the blends are generally relatively concentrated for practical transport and handling purposes. Liquid mixtures can themselves; in this case, it contains additives which promote the dissolution of the polymers, in which case concentrated mixtures can be used. Examples of such substances are alkoxyethanols such as butoxyethanol. Liquid blends 35 suitable for transportation and handling generally contain from 5 to 50% by weight of active cationic polymer of this invention. Although the surfactants of this invention are available separately from polymer blends. As mixtures of 17,92731, in which case they can be used for the treatment of felts separately (e.g. using a separate spray system) or can be mixed before use, it is preferred to use aqueous mixtures of both cationic surfactant 5 and cationic polymer. Although the compositions of this invention may also contain other agents, useful compositions of this invention may be prepared containing a resin control agent consisting essentially of the cationic surfactants described above and cationic polymers. Liquid mixtures suitable for transport and handling generally contain from 5 to 50% by weight of polymer and surfactant components, based on the total weight. The weight ratio of surfactant to polymer in such a composite blend is generally between 50: 1 and 1:50. The weight ratio of surfactant to polymer in the liquid mixture is preferably between 10: 1 and 1: 1, especially if oils may be present? and most preferably about 1: 1 for general applications, although an excess of surfactant (e.g., 1.1: 1 or more by weight) may be considered most appropriate in cases where oils may be present.

An aqueous mixture which is considered particularly suitable for the separate application of a polymer component together with the addition of a surfactant is available commercially from the Dearborn Chemical Co., Ltd. of

Ontario, Canada, and contains about 17% by weight of a condensation product of active polymer, formaldehyde, ammonium chloride, dicyandiamide, and formic acid, believed to have a molecular weight of between about 20,000 and 50,000, about 2% by weight of active polymer, obtained from the reaction between epichlorohydrin and dimethylamine and believed to have a molecular weight of between about 20,000 and 30,000, and about 8% by weight of butoxy-35 ethanol. Said product also contains small amounts of other substances, such as about 0.4% of an active alkyldimethylammonium chloride surfactant consisting of the above-described mixture of C12, C, 4- and C16-n-alkyl substituents, 18,92731 but these not considered necessary for a separate addition. The relative amount of alkyl dimethyl ammonium chloride surfactant in this product is considered insufficient to activate the polymer-5 antifouling effect of this invention. Another liquid mixture which is considered particularly suitable for the separate addition of polymer is also commercially available from Dearborn Chemical Co., Ltd. and contains about 17% by weight of active poly (hydroxyalkylene dimethylammonium chloride) having a molecular weight of about 20,000. a separate mixture of the surfactant of this invention is considered to be a liquid mixture, also prepared by Dearborn Chemical Co., Ltd., containing about 16% of the active alkyldimethylbenzylammonium chloride-15 surfactant mixture described above.

The dosage best suited for treatment depends on system factors such as the nature of the adhesive and whether the cleaning is continuous or intermittent. Also, relatively high concentrations of the polymer of this invention (e.g., 50%) can be used at full strength (100% as a liquid mixture), for example, by spraying the undiluted liquid mixture directly onto the felts. However, especially in the case of continuous treatment, it is advisable to dilute the mixtures at the treatment site with pure water or other aqueous liquids. Mi-: · (Kali water management requires, Good quality process waters can also be used for dilution.

The advantages of this invention can be realized at polymer concentrations of up to 2 ppm, especially in the context of continuous purification, and, as described below, with a sufficient amount of surfactant to prevent the formation of deposits from the added cationic polymer component. In this context, "continuous processing" of the felt means that the felt is routinely treated at least once during the cycle between the sheet contact step and the return step. This routine ♦ · treatment is best applied at the beginning of the return phase. The blanket can then contact the sheet so that the adhesion of tacky substances, including those contained in the recycled fiber material, to the felt is also prevented, and that the adhesive is easier to wash off when the aqueous washing solution is applied to the felt during the return step. In certain cases, continuous treatment is not practical and treatment with the cationic polymers and surfactants of this invention may be intermittent. For example, a liquid solution containing a polymer and a surfactant can be sprayed onto the felt until the felt is in sufficiently good condition, after which the spray is closed until the felt is in need of cleaning again.

The processing methods are described in more detail with reference to the felt systems used in papermaking, which are shown in simplified forms in Figures 1 and 2.

The press felt system corresponding to reference numeral 10 in Figure 1 includes an upper press felt 12, a lower press felt 14, a press press below the last press 16, and a press felt 18 above the last press 18. The press press 16 below the last press runs 22, a set of rollers 20, 21, 24, 25 and 26 and around the press roll 29; the lower press felt 14 extends around the set of rollers 30, 31, 32, 33, 34, 35 and 36 and the press rolls 37 and 38; the upper press felt 12 extends around the roll 40 series 40, 41, 42, 43, 44 and 45 and the press roll 47; and the press felt above the last press passes around the press roll 49 and the set of rollers 60, 61, 62 and 63. Both the upper press felt 12 and the lower press felt 14 pass between the press rolls 37 and 47. The lower press felt 14 passes between the press rolls 38 and 48; and both the press felt 16 below the last press and the press felt 18 above the last press pass between the press rolls 29 and 49. The jets used for washing the upper press felt 12, the lower press felt 14, the last press bottom 35 side press felt 16 and the last press felt upper press felt 18 correspond to reference numerals 50, 51, 52 and 53. The sheet support roller:. shown at 55. Press 57 comprises press rolls 37 and 20 92731 47; the press 58 comprises press rolls 38 and 48; and the press 59 comprises press rolls 29 and 49.

The press felt system 10 shown in Figure 1 is positioned to receive sheet material from a Fourdrinier wire type machine shown only partially in Figure 1 at 64 and having a wire 65 for receiving aqueous paper pulp from a headbox (not shown). The liquid is filtered through the openings in the wire as the wire passes through the sheet. During the contacting step, the fiber knob breaking roll 66 and the felt press roll 67, which are generally used to physically compress and remove the sheet material from the wire 65. The wire 65 passes over the guide roll 68 to return to receive more pulp. The return step generally passes a series of jets (not shown) and rollers corresponding to the wash roller 69. Other jets (not shown) may be used for certain parts of the system, such as the fiber knob breaking roll 66 or the guide roll 68.

During use of the felt system shown in Figure 1, the sheet material removed from the wire 65 after the felt press roll 67 is passed between the rolls 45 and 36 and pressed between the upper press felt 12 and the lower press felt 14 by the press rolls 37 and 47 of the press 57. The sheet 25 travels to the lower press felt 14 58, where it is pressed between the lower press felt and the press roll 48 by the press roll 38. The sheet material is then removed from the lower press felt 14 and fed to a press 59 where it is pressed 30 between the last press felt 16 below the last press felt and the press press 18 above the last press. with the press rolls 29 and 49 of the press 59. The sheet material is then removed from the press felt 16 of the last press and passed over the support roll 55 to subsequent processing equipment, such as drying equipment (not shown). The step of contacting the press felt 12 above the press felt system 10 shown in Figure 1 extends from the roll 45 or from a point between the roll 45 and the press 57 to a particular point after the press 57; the sheet contacting step of the lower press felt 14 extends from a point between the roll 36 and the press 57 to a certain point after the press 58; the sheet contacting step of the press felt 16 below the last press extends from the te-5 blade 26 to a certain point after the press 59; and the sheet contacting step of the press felt 18 above the last press extends from a point between the roll 63 and the press 59 to a certain point after the press 59.

It will be appreciated that the felt system 10 may include other accessories such as various presses, rollers, showers, guides, vacuum devices and tightening devices. In particular, felt wash rolls to remove moisture from the felt itself can be used. In addition, some of the devices shown in the figure, such as the press 58 and the felt 18 above the last press, may be omitted from the felt system. Furthermore, it will be apparent to one skilled in the art that felt systems vary widely in terms of the number of felts used and the felt circulation system.

Felt systems are also used in papermaking processes that do not use Fourdrinier wires. One such alternative system, which is particularly useful for making heavier sheet material, uses cylinder formers. The initial stages of the cylinder forming system are shown in Figure 2. The system 70 includes sets of wire cylinders, such as those shown in Figures 72 and 73, rotating so that a portion of the cylinder contacts the pulp, after which the cylinder rotates 30 to transfer the felt web to the felt felt felt 75. The system 70 includes In addition, the first upper felting felt and the second upper felting felt 77. The felting rollers 78 and 79 are used to facilitate the transfer of the sheet material 35 from the cylinders 72 and 73 to the lower felting felt.

The lower felting felt 75 passes around the felt rolls 78 and 79, the roll 80, the suction roll 81 and the press rolls 83, 84, 85 and 86. The first top felting felt passes around rollers 88, 89 and 90 and a suction felt roll 91; and 92731 22 the second upper felt roll passes around the press rolls 93, 94, 95 and 96 and the rollers 97, 98, 99 and 100. Both the lower felting felt 75 and the first upper felting felt 76 pass between the suction roll 81 and the suction felt roll 5 91, whereby water is absorbed from the felts and the fibrous web. Both the lower felting felt 75 and the second upper felting felt 77 pass between the press rolls 83 and 93, between the rollers 84 and 94, between the rollers 85 and 95, and between the rollers 86 and 96. The press 103 comprises 10 press rolls 83 and 93; press 104 comprises press rollers 84 and 94; press 105 comprises press rolls 85 and 95; and the press 106 comprises press rollers 86 and 96.

The lower felting felt 75, the first upper felt-15 felting felt 76 and the second upper felting felt 77 are washed with jets 107, 108 and 109.

In connection with the use of the felts shown in Figure 2, the sheet material transferred from the cylinders 72 and 73 passes through the lower felting felt 75 over the suction roll and is pressed between the lower felting felt and the second upper felting felt 77 by presses 103, 104, 105 and 106. The sheet material is then and 77 and fed to subsequent processing equipment, such as the felt system 10 shown in Figure 1. Note 2. the sheet contacting step of the felting felt 75 below the bead system extends from the cylinder 72 to a point immediately after the press roll 86; the sheet contacting step of the first top felting felt is at the suction felting felt; The sheet contacting step of the felt felt 30 and the second top extends approximately from the roll 100 immediately after the press 96. It will be appreciated that the felt system 70 may include other accessories such as cylinders, presses, rollers, jets, guides, vacuum devices, and crossover devices. In addition, some of the devices shown in the figure may be omitted from the forming system. Alan tun-. . Furthermore, it is clear to the person skilled in the art that the forming systems vary very much in terms of the number of blankets used and the felt circulation system.

Il 23 92731

Each felt 12, 14, 16, 18, 75, 76 and 77 shown in Figures 1 and 2 can be continuously treated in accordance with the present invention by applying an aqueous solution of a suitable cationic polymer and surfactant to any part of the felt during the return step (i.e., from , where the felt is separated from the contact of the sheet, to the point where the felt again touches the sheet material). The solution is preferably sprayed onto the felt at the beginning of the return step so that the adhesive material transferred from the sheet material to the surface of the felt can be treated as soon as possible. However, the treatment point is often limited by the structure of the felt system. The jets 50, 51, 52, 53, 107, 108 and 109 shown in Figures 1 and 2 can be used for treatment purposes. In cases where the solution used is more concentrated than the solution required for continuous treatment, application can be interrupted and introduced as needed. For example, in cases where showers such as showers 50, 51, 52, 53, 107, 108 and 109 are used, the showers can be periodically opened and closed. in accordance with the requirements of the system. Devices other than blankets can also be handled in a similar manner suitable for their operation.

In typical papermaking processes, especially those using substantial amounts of recycled fiber material, the amount of cationic polymer added is generally at least about 0.002 grams per square meter of felt per minute (g / m2-min), preferably about 0.01 g / m2-min or more of the treatment. continuous, and preferably about 0.02 g / m 2 min or more during the treatment period, with the treatment being intermittent. Preferably, at least 0.5 grams of polymer per square meter per minute or less is used to minimize possible felt clogging. Conventional paper machines with felts 2-7 meters wide and 10-40 meters long generally apply about 0.02-20 grams of 35 soil polymer per minute per meter of width (i.e., g / m-min), more generally about 0.05- 12.5 g / m-min. In one method, 1 g / m-min or more is applied initially until the blanket is • repaired. Once the blanket is thus repaired, the amounts of polymer used later may be lower, or 92731 24 as described above, the application may also be intermittent. The surfactant is applied to the felts in an amount sufficient to prevent the formation of deposits derived from the applied polymer and thus plays an important role in preventing clogging of the felts. The weight ratio of surfactant to polymer is therefore maintained between about 50: 1 and 1:50. In order to have a sufficient surfactant to prevent the formation of polymer-derived deposits and to protect against random amounts of dirty and oily materials from the pulp 10, the ratio of surfactant to polymer is preferably considered to be about 1: 1 or more; and to avoid excessive use of the surfactant, the ratio of surfactant to polymer is considered to be about 10: 1 or less. The weight ratio between the two components is most preferably 1: 1. In any case, it is recommended to use a surfactant with a concentration of at least about 1 ppm. Other devices such as wires, screens, filters, rollers, and suction boxes, and materials such as metal, granite, rubber, and ceramics can also be successfully processed in accordance with this invention. However, the present invention is particularly useful for the treatment of felts and the like having pores for dewatering (i.e., relatively small pores) in which the formation of substantial deposits derived from the polymer: is undesirable; compared to, for example, other equipment parts, such as metal and plastic wires, which have relatively large pores for dewatering and in which the formation of deposits to a certain degree is not expected to cause undesired difficulties.

«

In any case, the concentration of the cationic polymer applied to the surface of the felt or other papermaking equipment as an aqueous solution should be at least about 0.0002% by weight. In order to distribute the polymer evenly, the treatment according to the invention is preferably carried out with an aqueous spray solution containing about 0.0002 to 0.2% by weight of cationic polymer.

Il 25 92731

The invention is illustrated by the following practical examples, which are not intended to limit the invention.

Example 1 5 The experiment of this example was performed on a paper machine equipped with a Fourdrinier wire. The machine had an upper first press felt, a lower first press felt, an upper second press felt and a lower second press felt, which mainly correspond to the upper press-10 felt 12, the lower press felt 14, the last press above the press felt 18 and the last press 16. Each blanket was equipped with a shower. The first press felts received a sheet material of a Fourdrinier-vii-15 strip located at almost the same location as the unit 64 shown in Figure 1 and produced corrugated paper pulp containing about 20% recycled (recycled) fibrous material and about 80% virgin hardwood fiber material.

The sheet material formed by the wire was separated from the wire and conveyed to a first press, which corresponded almost to the press 57 shown in Fig. 1, in which the sheet material was pressed between the first upper press felt and the first lower press felt. The sheet was then removed from the first press felts and conveyed to a second press, corresponding substantially to the press 59 shown in Figure 1, in which the sheet material was pressed between the second upper press felt and the second lower press felt.

30

The formation of deposits <··· on the press felt, especially on the second overhead press felt, had recently been observed in a paper machine. The deposits consisted of resins 35 and stickies from the pulp and recycled material and migrated to the felts from the fibrous web in contact with them. Sheet breaks at the second press were a constant problem «: and sometimes occurred even once during an eight-hour shift. Periodic downtime 26,927,731 was therefore necessary to reduce the number of sheet breaks. The second upper press felt was about 6.1 m wide and 18.8 m long (i.e., the treatment area of the second upper press felt 2 was about 114.7 m).

5

The second overhead press felt was treated in accordance with the present invention by mixing a test product of high pressure jet jet water located at a location almost corresponding to the jet 53 shown in Figure 1, containing about 7.5% by weight of the 10 * "12" '^ 14 "^ 1-n-alkyl substituents described above. a mixture of alkyldimethylbenzylammonium chloride, and about 7.5% piano of a polymer having a molecular weight of about 20,000 derived from dimethylamine and epichlorohydrin, and about 85% solvent (the solvent consisted mainly of water with 15 minor amounts of random substances such as ethanol, premixed with a commercial surfactant and / or polymer preparation), the dosage was initially about 0.06 2 g / min / m for each component, and the dose was reduced to about 0.02-0.03 g / m 2 after 4 hours. min / m.

The efficiency of the treatment was monitored with a Huyck & Smith porosity tester as the number of breaks at the second press stage. The porosity of a felt is considered a measure of the capacity of the felt to absorb water from the sheet. Very porous. 25 felts (i.e., a felt with many open pores) are considered desirable for sheet dewatering.

The relative porosity of the second upper press felt was monitored during the 21 day experiment using the Huyck 30 & Smith method using relative porosity numbers (H.S. numbers) ranging from the highest value for 100% non-porous or clogged felts to lower percentages for more porous felts. The H.S. of the second upper press felt remained at about 35% during the first 35 days of the test. The supply of the treatment product was cut off for more than 24 hours. The H.S. figure then rose to about 50% and • was related to the interruption of treatment. The blanket was cleaned and 27,92731 tests were continued. After continuing the test, the H.S. number dropped to 45%, where it remained for several days. The dosing of both treatment components was reduced by about half due to pump malfunction and the H.S. figure increased to 53%. Dose-5 lu was restored to the previous level and the H.S. number remained at about 53% for the rest of the test.

Porosity measurements made during the test showed that when the polymer and surfactant were used according to the present invention, the porosity of the felt could be kept unchanged. When the supply of these substances was cut off, the clogging of the felt increased by about 15-40%. In addition, sheet breaks caused by the second overlay press felt could be eliminated throughout the 30-day period. From this it could be concluded that the treatment according to the present invention would prevent the occurrence of interruptions and downtimes caused by deposits in the second press; that the treatment would prevent the accumulation of adhering substances on the treated felt; and that the clogging of the felt by the fibers was significantly reduced during processing.

Example 2 The test of this example was performed on a cylinder machine (unlike the Fourdri-Nier wire machine). The machine had a first lower 25 side felt, a suction felt felt and a first upper *; felt, which mainly corresponds to the lower felting felt 75 shown in Fig. 2, the first upper felting felt 76 and the second upper felting felt 77. The machine also had a second upper felt, a second lower 30 felt and a last press felt, which mainly correspond to the upper felt shown in Fig. 1. felt 12, a press felt 14 below, and a press felt 16 below the last press. (Thus, the machine did not have a felt corresponding to the press felt 18 35 above the last press.) Each felt had showers. The machine had 7 wire cylinders installed in series, which mainly correspond to the wire cylinders 4 • 72 and 73 shown in Fig. 2, and the machine produced board (e.g. straw board or recycled fiber board) from 100% recycled pulp.

28 92731

The paper web formed by the cylinders was transferred to the first lower felt, where the sheet was pressed between the first lower felt and the suction felt felt and passed through about four presses between the first lower felt and the first upper felt. The sheet was then detached from the first lower felt and passed to a second press, which was closest to the press 57 shown in Figure 1 and in which the sheet was pressed between the second upper felt and the second lower 10 felt. The sheet was next separated from the other press felts and transported to the felt of the last press, where it was re-pressed in a press similar to the press 59 shown in Fig. 1 using an overhead press roll without a felt.

15

Before performing the test with the combination of a cationic polymer and a cationic surfactant according to the present invention, the first lower blanket, the suction felting blanket, the first upper blanket and the second upper blanket were pretreated in a conventional manner with an alkyldimethylbenzylammonium chloride product containing a mixture of n-alkyl substituents, using jets whose positions corresponded mainly to the positions of jets 107, 108, 109 and 50 shown in Figures 1 and 25.

: The test solution used in the test, containing about 7,5% by weight of a mixture of alkyldimethylbenzylammonium chloride, 7,5% by weight of a polymer with a molecular weight of about 20 000 derived from dimethylamine and epichlorohydrin, and about 85% by weight of solvent (i.e. The same product as in Example 1) was used, added to the jet water,: the concentration was estimated to be about 2.6 ppm of both surfactant and polymer, and the mixture was applied to the four felts in question. When no clogging was observed in the felts due to the initial addition of polymer, the concentration of both the surfactant and the polymer was increased by 50% (whereby the concentration was estimated to be 4 ppm). Treatment was left at this level for the remainder of the test period. Each component was applied to each felt at about 1.5 grams / minute at the beginning of the test and at about 2.25 grams / minute at the end of the test. The width of the first lower felt, the suction-5 felting felt, the first upper felt and the second upper felt was about 2.35 m and the lengths of each felt were 31.7 m, 18.9 m, 20.1 m and 12.8 m, respectively (i.e. .treatment areas were approximately 74.5 m2, 44.4 m2, 47.2 m2 and 30.1 m2).

1 0

Relative porosities were measured during the test in the width direction of the vacuum-treated felts as well as in the width direction of the untreated second lower felt. The considerable increase in vacuum meant that the condition of the blankets deteriorated.

15 The results are shown in Tables 1-5.

table 1

Porosity of the first felt below 20

Time Application rate ^ Relative porosity (kPa) (min.) (Approx.) G / min / m Front Front Middle Rear Rear aliopolymer / surface- End Middle Central Active on end 25 _material • • · · • After pre-treatment 30.5 27, 1 33.9 37.2 27.1 0 Feed started - 5 0.02 0.02 30.5 27.1 33.9 37.2 27.1 30 40 0.02 0.02 37.2 30.5 27.1 27.1 27.1 65 0.02 0.02 33.9 27.1 27.1 27.1 27.1. 100 0.03 0.03 33.9 33.9 30.5 30.5 33.9 135 0.03 0.03 37.2 33.9 33.9 33.9 30.5 215 0.03 0, 03 33.9 33.9 30.5 30.5 33.9 35 245 The feed was stopped - 265 0 0 33.9 33.9 33.9 33.9 33.9 '· · 30 92731

Table 2

The porosity of the suction felt felt

Time Application rate ^ Relative porosity (kPa) (min.) (Approx.) G / min / m Front Front Middle Rear Rear 5 aliopolymer / surface- End Central Central End active _substent _

After pre-treatment 6.8 6.8 6.8 6.8 6.8 10 0 Feed started - 5 0.03 0.03 6.8 6.8 6.8 6.8 6.8 40 0.03 0, 03 10.2 10.2 10.2 6.8 10.2 65 0.03 0.03 10.2 10.2 10.2 10.2 10.2 100 0.05 0.05 6.8 6, 8 6.8 6.8 6.8 15 135 0.05 0.05 10.2 10.2 6.8 6.8 6.8 215 0.05 0.05 13.5 13.5 10.2 10 , 2 16.9 245 The feed was stopped _____ 265 0 0 10.2 10.2 10.2 10.2 10.2 290 0 0 13.5 10.2 10.2 10.2 10.2 20 _

Table 3

Porosity of the first felt above

Time Application rate ^ Relative porosity (kPa) 25 (min.) (Approx.) G / min / m Front Front Middle Rear Rear aliopolymer / surface- End Middle Central Active from end, _ substance_ 30 After pre-treatment 10.2 13.5 13 .5 13.5 13.5 0 Feed started - 5 0.03 0.03 10.2 13.5 13.5 13.5 13.5 40 0.03 0.03 13.5 13.5 13.5 13.5 13.5: 65 0.03 0.03 13.5 13.5 13.5 13.5 13.5 35 100 0.05 0.05 13.5 13.5 13.5 13.5 13 .5,135 0.05 0.05 16.9 16.9 16.9 13.5 13.5 215 0.05 0.05 16.9 16.9 13.5 16.9 16.9 245 Feeding stopped _ 265 0 0 16.9 13.5 13.5 13.5 13.5. 40 _

II

31 92731

Table A

Porosity of the second felt above

Time Application rate ^ Relative porosity (kPa) (min.) (Approx.) G / min / m Front Front Middle Rear Rear 5 aliopolymer / surface- End Middle Central End active _ material_________

After pre-treatment 6.8 10.2 10.2 10.2 10.2 10 0 Feed started - 5 0.05 0.05 6.8 10.2 10.2 10.2 10.2

AO 0.05 0.05 6.8 3, A 3, A 0 3, A

65 0.05 0.05 6.8 6.8 10.2 10.2 10.2 100 0.07 0.07 6.8 10.2 6.8 6.8 6.8 15 135 0.07 0 .7 10.2 10.2 6.8 6.8 6.8 215 0.07 0.07 13.5 13.5 16.9 13.5 13.5 2A5 Feeding stopped - 265 0 0 13.5 13 , 5 16.9 13.5 13.5 20

Table 3

Porosity of the second felt below (untreated)

Time Application rate ^ Relative porosity (kPa) (min.) (Approx.) G / min / in Front Front Middle Rear Rear 25 aliopolymer / surface- End Middle Central End active active _ substance_ I · ·

After pre-treatment 10.2 10.2 16.9 13.5 16.9 30 0 Feed started - 50 0 10.2 10.2 16.9 13.5 16.9 AO 0 0 16.9 13.5 13, 5 16.9 13.5 65 0 0 16.9 16.9 13.5 13.5 13.5 100 0 0 13.5 13.5 13.5 13.5 10.2 35 135 0 0 16.9 16.9 16.9 13.5 16.9 215 0 0 16.9 16.9 10.2 13.5 16.9 265 0 0 16.9 16.9 10.2 13.5 16.9 32 92731

It is apparent from Tables 1-5 that the cationic polymer can be applied to paper machine felts in accordance with the present invention without the felts clogging or suffering from porosity. The pressure loads (i.e., the pressures used in the six presses of the paper machine) 5 remained unchanged during the test period; and vacuum pressures (i.e., suction used to remove fluid from the felts) measured at 13 points for the first lower felt, suction felt felt, first upper felt, second upper felt, and second lower felt also remained unchanged during the 10 test periods. The felting vacuum remained unchanged during the test. During the test, various paper properties were also monitored, which are summarized in Table 6.

Table 6 15 Paper properties

Time (min) Speed Humidity in square ^ Caliper * from start_ (m / min) _ [%) _ (g / m -) _ (microns)

After pretreatment 20 69.6 5.9 552, A 802.9

The speed of the machine was reduced before starting the test by 15 66.9 A, 6 557.3 820, A

50 66.9 3.2 538.9 813.9 60 Mass flow was increased due to low humidity and caliper 25 100 Treatment agent feed was increased 215 69.6 A, 5 550.2 823.8 2A5 Treatment was stopped 265 71, AA, 9 551, 7,822.6 30 _ * It was found that Caliper gave values 25 microns higher than the actual values due to a computer error.

The pulp had a pH of about 6 and a tank temperature of about 38 ° C. 35 The consistency of the pulp was about 0.37% in cylinders 1 and 7 and about 0.1% in cylinders 2, 3, A, 5 and 6. The paper quality was maintained. unchanged during the test. The optimum moisture content was considered to be 5%, and the optimum caliper was considered to be about 800.

33 9 2 7 31

It can be seen from Table 6 that the desired sheet moisture could be maintained during processing and that high speed could be maintained during and after processing of the felts of this invention.

5

Example 3 The experiment of this example was performed on a paper machine with a single Fourdrinier wire with a capture felt and a set of presses and blankets leading to a Yankee dryer. The machine normally processed 10 pulps containing a substantial portion (i.e., about 40-100%) of deinked recycled pulp. The pulp had a pH of 6.0-6.5 and a temperature of about 40 ° C. The daily production volume of the machine was about 50 tons.

Prior to testing, the blanket had to be washed approximately 15 times daily as an organic solvent and / or mixtures of an organic solvent and detergent. Approximately 22.8 liters of solvent were used per wash (i.e., approximately 342 liters of solvent daily). Solvent washes were performed during use at intervals determined by the paper grade. Significant quantities of paper could not be sold due to poor quality. The relatively inexpensive and therefore the desired amount of deinked recycled pulp was found to cause operational disturbances during processing, which in turn can lead to deterioration and / or breakage of the sheet. For practical reasons, the amount of deinking pulp used was limited to a maximum of about 60%.

Prior to testing, a new catch felt was installed, approximately 2.7 meters wide and 16.2 meters long. For the capture felt, 30 two lubrication jets were installed. Typical I. the service life has been about 50 days. The new low pressure shower was installed for testing the felt side of the sheet about a meter before the end of the suction box. The shower used clean water and had 13 nozzles, each with a water flow of 9.1 liters in 35 minutes.

• ·

In the test, a test product containing about 7.5 34,92731% by weight of a mixture of alkyldimethylbenzylammonium chloride, about 7.5% of a polymer having a molecular weight of about 20,000 derived from dimethylamine and epichlorohydrin, and about 85% by weight of solvent (i.e. the product used in Examples 1 5 and 2), to a low pressure jet of pure jet water to give an estimated concentration of about 34 ppm of both surfactant and polymer, and about 0.09 g / m 2 min of both surfactant and polymer were applied to the felt.

10

Although the porosity of the felt was not measured on this machine, it could be seen during the hours after the start of the test that the intervals between solvent cleanings of the felt could be extended. The proportion of deinking pulp was also increased to 100%. The amount of solvent washes decreased to about 5-12 washes per day for five days, and the amount of solvent required for one solvent wash could be reduced to about 13.6 liters per wash, reducing the amount of solvent required per day to about half (i.e., to about 164 liters per day).

20

The low pressure jet was then moved to a new location after the suction box. The amount of solvent washes could then be reduced about 3 times daily. The new location of the shower could thus be said to represent an improvement.

25

The composition of the pulp was next changed to include 60% deinking pulp and 40% virgin pulp. The number of solvent washes for this pulp grade decreased to about one daily wash.

30

In summary of this 18-day preliminary test, the treatment of this machine's felt according to the present invention can provide significant cost savings by allowing the use of a large amount of deinking pulp without unacceptable operating disturbances, reducing the number of solvent washes required for efficient production and washing. increased the number of 35 92731 grippers, and by reducing the amount of poor quality finished paper.

The examples describe various embodiments of this invention. Other embodiments will be apparent to those skilled in the art from the specification or practice of the invention described herein. It is to be understood that modifications and variations may be made without departing from the spirit and scope of the novel concepts of this invention. It is also to be understood that the invention is not limited to the specific compounds and examples described herein, but encompasses such modified forms of the invention as fall within the scope of the following claims.

«4

Claims (44)

A method for preventing sticky materials from sticking to paper machine blankets or similar machine components used in the processing of paper pulp tiles, characterized in that it comprises the following steps: (a) A water solution containing at least about 2 ppm of a machine solution is applied to said machine components. cationic polymer; and (b) applied to said machine components an aqueous solution containing at least one compound from the group of water-soluble nonionic and cationic surfactants; and that the surfactant is applied in an effective amount that prevents the formation of coatings originating from the cationic polymer. 25 Process according to claim 1, characterized in that the cationic polymer is a dicyandiamide-formaldehyde condensation polymer, which further contains at least one compound from the group containing formic acid and ammonium salts as starting materials for the polymerization. Process according to claim 2, characterized in that the cationic polymer is derived from a reaction between formaldehyde, dicyandiamide, formic acid and ammonium chloride. 4. A process according to claim 1, characterized in that the cationic polymer is obtained by reaction between epihalohydrin and one or more amines, or derived from ethylenically unsaturated monomers containing a quaternary ammonium group. Process according to claim 1, characterized in that the cationic polymers are protonated or contain quaternary ammonium groups. Process according to Claim 1, characterized in that the cationic polymer is obtained by reacting epihalohydrin with at least one compound from the group containing diethylamine, dimethylamine and methylethylamine. Process according to claim 6, characterized in that the cationic polymer is prepared by reacting epichlorohydrin with dimethylamine. Process according to claim 6, characterized in that the cationic polymer is prepared by reacting epichlorohydrin with diethylamine. Process according to claim 1, characterized in that the concentration of the cationic polymer in the aqueous solution is about 0.0002-0.02% by weight and the weight ratio of the surfactant applied to the felt is applied. the polymer polymer is from about 50: 1 to about 1:50. Method for monitoring the accumulation of material on a paper machine felt, which pivots between the sheet touch stage and the return stage according to claim 1, characterized in that the surfactant and the cationic polymer are applied to the paper machine felt in the same aqueous solution during the return stage of the felt. the surfactant and polymer are from about 50: 1 to 1:50. 35 Method according to claim 10, characterized in that the aqueous solution is substantially free of anionic macromolecules. 92731 46 12. A process according to claim 10, characterized in that the cationic polymer is applied in an amount of at least about 0.002 g / m 2 min. 13. A method according to claim 10, characterized in that the coatings on the blankets receiving material from the cylinders of the cylinder machine can be monitored. 14. A method according to claim 10, characterized in that the coatings on the blankets receiving sheet material from the machine cloth in a Fourdrinier machine can be monitored. 15. A method according to claim 10, characterized in that the felt is continuously treated with the aqueous solution. Process according to claim 15, characterized in that the cationic polymer is applied in an amount of at least about 0.01 g / m 2 min. 17. A method according to claim 10, characterized in that the blanket is treated with the aqueous solution periodically. 25 18. Process according to claim 17, characterized in that the cationic polymer is applied in an amount of at least about 0.02 g / m 2 min during the application period. The method according to claim 1, characterized in that at least about 10% of the pulp fibers of the papermaking machine are derived from ether-used material. 20. A method according to claim 1, characterized in that the pulp fibers of the paper machine are derived from about 100% of the material used. II 92731 47 21. A method according to claim 1, characterized in that the mass of the papermaking machine is mainly derived from tali containing about 2% by weight of resin or more. 22. A process according to claim 1, characterized in that the aqueous solution containing the surfactant contains at least 1 ppm of the surfactant. The method according to claim 1, characterized in that the applied surfactant is selected from the surfactants whose molecular weight is from about 20 ° to 800 and which has the general formula R 15. N + X- R s' '' '' '' SSSVS'R where each R is separately selected in the group consisting of hydrogen, polyethylene groups, polypropylene oxide groups, alkyl groups containing 1-22 carbon atoms, aryl groups and aralkyl groups, and wherein at least one of said R groups contains at least 8 carbon atoms, and where X 'is an anion or 1 / n of an anion with n-valence. The process according to claim 23, characterized in that at least one R group of said surfactant is an n-alkyl group containing about 12-16 carbon atoms. 25. A process according to claim 24, characterized in that two R groups of said surfactant are methyl and ethyl, and one R group is -CH -, - and <ϋ> CH 2 -CH 2 -. Process according to claim 24, characterized in that the surfactant is a mixture of alkyl dimethyl ammonium chloride or alkyl dimethyl ammonium chloride. 27. A method of treating paper machine blankets which pivot between the sheet touch step and the return step and which is used in the process treatment of pulp tiles, to prevent sticky hydrophobic substances from sticking to the felt, characterized in that the method comprises the following steps: during the return step, an aqueous solution containing (i) at least about 2 ppm of a cationic polymer having a molecular weight from about 10,000 to 300,000 and (ii) a water-soluble surfactant having a molecular weight from about 200 to 800 and with the general application is applied. wherein each R is separately selected in the group containing hydrogen, polyethylene groups, polypropylene oxide groups, alkyl groups containing 1-22 carbon atoms, aryl groups and aralkyl groups, and wherein at least one of said R groups contains at least 8 carbon atoms, and where X 'is an anion or 1 / n of an anion having 20 n-valence; and wherein said surfactant is applied to the felt in an amount effective to prevent the formation of coatings originating from said polymer; and where an effective amount of said cationic polymer is applied from about 0.002 to 0.5 grams per minute per square meter of felt, such that the cationic polymer and the surfactant affect the hydrophobic material, so that it essentially loses its ability to adhere to the felt. . 28. A method according to claim 27, characterized in that the paper machine felt is used in a system selected from the cereals in which the proportion of return fibers in the system *: fibers is at least about 10% and in which 5% or more of the fibers are derived from tallow containing over 2% by weight of resin. 35 29. A method according to claim 27, characterized in that the felt is routinely treated at least one thread during the cycle consisting of the sheet touch stage and the return stage, n 92731 49 and that the polymer is applied in an amount of at least about 0.01 grams per minute per square meter of felt. 30. A method according to claim 27, characterized in that the aqueous solution is sprayed onto the felt in an amount of at least about 0.02 grams of cationic polymer per minute per square meter of felt, until the felt is in a satisfactory condition, and that the spraying is completed thereafter. until the blanket needs to be refitted to prevent the formation of coatings on the blanket. 31. A method of monitoring a build-up of adhesives on paper machine blankets in a papermaking system, in which the proportion of return fibers of the system fibers is at least about 10%, and in which the blankets oscillate between the sheet touch stage and the return stage used in sheet processing of pulp containing both anionic macromolecules and adhesives, characterized in that the process comprises the following steps: during the return step, an aqueous solution which is substantially free of anionic macromolecules and containing (i) at least about 2 ppm of a cationic polymer having a molecular weight of about 10 is applied. And (ii) a water-soluble surfactant having a molecular weight of from about 200 to about 800 and having the general formula: RR + n + r Where each R is separately selected in the group containing hydrogen, polyethylene groups, polypropylene oxide groups, alkyl groups containing 1-22 carbon atoms, aryl groups and aralkyl groups, and wherein at least one of said R groups contains at least 8 carbon atoms and where X * is an anion or 1 / n of an anion with n-valence; and wherein said surfactant is applied to the felt in an effective amount to prevent the formation of coatings derived from said polymer; and wherein said cationic polymer is applied with the weight ratio of surfactant: polymer from 10: 1 to about 1: 1, and which reacts with the anionic macromolecules and adhesives to form products which are easy to detach from the felt. 5 32. A process according to claim 31, characterized in that the amount of recycled fibers is at least 70% of the system fibers, and that the cationic polymer is applied to the felt in an amount of at least about 0.002 grams per minute per square meter of felt. 33. A mixture for monitoring an accumulation of sticky substances on paper machine blankets and the like, characterized in that it contains: (a) a cationic polymer; and (b) a water-soluble surfactant having a molecular weight from about 200 to 88 and having the general formula: R 20 + N + X 'where each R is separately selected in the group containing hydrogen, polyethylene groups, polypropylene oxide groups, alkyl groups containing 1-22 carbon atoms, aryl groups and aralkyl groups, *. and wherein at least one of said R groups contains at least 8 carbon atoms, and wherein X 'is an anion or 1 / n of an anion having n-valence; and wherein the weight ratio of the surfactant to the cationic polymer is from about 50: 1 to about 1: 1. 30 34. A composition according to claim 33, characterized in that the molecular weight of the cationic polymer is from about 10,000 to 3,000,000. A mixture according to claim 34, characterized in that the cationic polymer is a dicyandiamide-formaldehyde condensation polymer, which further contains at least one compound from the group containing formic acid and ammonium salts as starting materials for the polymerization. A mixture according to claim 34, characterized in that the cationic polymer is derived from a reaction between formaldehyde, dicyandiamide, formic acid and ammonium chloride. A mixture according to claim 34, characterized in that the cationic polymer is obtained by a reaction between epihalohydrin and one or more amines, or derived from ethylenically unsaturated monomers containing a quaternary ammonium group. A mixture according to claim 34, characterized in that the molecular weight of the cationic polymers is about 300,000 or less and that they are either protonated or contain quaternary ammonium groups. 39. A composition according to claim 34, characterized in that the cationic polymer is obtained by reacting epihalohydrin with at least one compound from the group containing diethylamine, dimethylamine and methylethylamine. Mixture according to claim 34, characterized in that at least one R group of said surfactant is an n-alkyl group containing about 12-16 carbon atoms. A mixture according to claim 40, characterized in that two R groups of said surfactant are methyl and ethyl, and an R group is <3> -CH2- and -ch2-ch2-. 42. A mixture according to claim 40, characterized in that the surfactant is a mixture consisting of alkyl dimethyl ammonium chloride or alkyl dimethyl ammonium chloride. 92731 52 43. A composition according to claim 42, characterized in that the cationic polymer is derived from dimethylamine and epichlorohydrin and that the molecular weight of the cationic polymer is about 20,000. 44. A mixture according to claim 34, characterized in that the mixture is an aqueous solution containing in total from about 5 to 50% by weight of said polymer and said surfactant. 10 45. A composition according to claim 34, characterized in that the weight ratio of the surfactant to the cationic polymer is from about 10: 1 to about 1: 1. 46. A composition according to claim 45, characterized in that the weight ratio of the surfactant to the cationic polymer is 1.1: 1 or greater. II »II: