FI115476B - Process for preventing resin deposition in pulp and paper making processes - Google Patents

Abstract

A method for inhibiting the deposition of pitch or stickies on and/or for removing pitch or stickies from the surfaces of pulping and papermaking machinery by adding an effective amount of a melamine formaldehyde-type polymer to a pulp slurry or furnish in contact with said machinery.

Description

115476

Method for preventing the precipitation of pitch and adhesives in pulp and papermaking processes

BACKGROUND OF THE INVENTION The present invention relates to the use of melamine-aldehyde-type polymers to prevent and / or combat resin and adhesive component precipitates in pulp and papermaking processes. More particularly, the present invention relates to the prevention of pitch deposition on machines used in pulp and papermaking processes and the removal of pitch on machines used in pulp and papermaking processes. The present invention further relates to the prevention of the deposition of adhesives on machines used in pulp and papermaking processes and the removal of tars from machines used in pulp and papermaking processes.

Resin, adhesives and stickers are a constant problem in pulp and paper mills. It is estimated that the problems resulting from the accumulation of pitch or adhesives and tackifiers in the pulp and papermaking industry. paper and final paper costing pulp and paper; · T * industry many millions of dollars a year in production I> l | in a lost form. As used in this patent application, resin

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h ·. * can be generally defined as a resin-based, composition-

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*. * 25 is a widely varying precipitate, derived from the extraction fraction of wood. The extraction fraction of wood is one of the four main components of wood: V: The other three are cellulose, lignin and hemicellulose. The extraction fraction is defined as a complex mixture of substances soluble in water, alcohol, benzene, ethyl, 2 · 3, · ter and / or acetone. The extraction fraction, which generally represents about 3 to 10% by weight of the wood, contains components such as low molecular weight carbohydrates, terpenes, aromatic and aliphatic acids, alcohols, tannins, dyes, proteins, lignins! And alkaloids and soluble lignins.

2 115476 As used in this patent application, the terms "tackifiers" and "tackifiers" are alternative terms that include primarily synthetic defects carried with recycled fibers. Examples of adhesives and tackifiers include, but are not limited to, ink residues, tars, latexes, and melt impurities found in recycled fibers. The adhesives and the tackifiers per se must be separated from the resin, which, as described above, comprises each resin-based precipitate 10, which has a wide variation in composition and is derived from the extraction fraction of wood. The constituents of pitch are naturally occurring in difference from the synthetic compounds which form the adhesive. Although resin and tackifiers cause similar problems in papermaking, they differ in their origin and composition.

Resin is a major problem in pulp and paper making because (1) it agglomerates and also encapsulates other material, resulting in the appearance of "dirt" in the final paper, (2) spreading and collecting on machines such as wires, filter mills used in the pulp and paper making process. , for mass scrubbers and paper machines, ·· and (3) reduce brightness and lightness retention. Pulp 1 for machines used in the production of paper and paper and lo. ·. composition and amount of resin precipitated on the bulging paper. . The types of wood used vary depending on the harvester, the type of wood and the type of cooker used. . 'Process type. For example, wood that is boiled var- *; I harvest from trees felled in spring or autumn, * usually contains more resin than wood that is cooked from trees felled at other times of the year. In the resin that precipitates: at 30 softwood sulphate mills, the ratio of abietic acid to fatty acid *: blades tends to be relatively higher,; than in the resin of hardwood sulphate mills and the resin precipitation problems are generally slightly more difficult in the sulphite mill. The sulphite cooking process removes only about half of the ·. : 35 stands and fat esters, leaving a considerable portion of these 3,115,476 materials encapsulated in cellulosic fibers. However, these encapsulated materials are released by shear forces occurring in pulp and papermaking processes, and resin deposits thus occur more commonly within 5 minutes in the papermaking region and on the surfaces of the papermaking machine. Resin problems can be quite troublesome at mechanical pulp mills, including pulp, TMP, CTMP, and semi-chemical pulping processes, especially softwood processes. This is due to the low chemical degradation of fatty acid esters and resin esters. Thus, these materials cannot be removed by washing and tend to remain dispersed in the aqueous system of the cooking process.

Adhesives and tackifiers are a major problem in recycled fiber pulp and paper making because, like pitch, (1) agglomerates and encapsulates other material into visible "dirt" in finished paper, (2) spreads and accumulates on machines used in the pulping and papermaking process. fabrics, filter grinders, pulp washers and paper machines, and (3) reduce pulp brightness and brightness stability. Composition of adhesives deposited on machines used in the pulp and paper industry and on high-density paper. *. The amount and quantity vary according to the type of recycled fiber * ·. ·: 25 used in the cooking. As used in this patent application.>. * The term "recycled fiber" includes all paper fibers which are · ·; is repeatedly used to make a paper end product.

Recycled fiber sources include, but are not limited to, moped tissue paper, fine paper, packaging paperboard, linerboard paperboard, tray paperboard, and newsprint. Each: These sources contain unique impurities such as inks, dyes, fillers, reinforcing resins and / or coatings. This means that the composition and concentration of the 4,115,476 adhesives may vary widely from one fiber to another.

The presence of calcium carbonate in cooking processes exacerbates the problem of pitch and / or adhesives being precipitated on pulp and papermaking machines. Crystalline calcium carbonate is capable of providing nucleation sites to precipitated metal soaps, thereby producing hydrophobic particles which merge with other particles to form a pitch precipitate.

10 Over the years, many efforts have been made to eliminate the country's resin or infectious matter problems by adding pesticides to pulp and / or papermaking processes. Although more thorough scrubbing of the pulp may help to reduce resin or tackifier problems, most treatments 15 include adding dispersants or adsorbents to the blend ratio. Can be treated, for example, with alum, talc, anionic resin agents such as polynaphthalene sulfonates or modified lignosulfonates, cationic resin agents such as polycarbonate ammonium polymers, methyl cellulose-free ionic derivatives, and the like. None of these treatments are particularly considered. effective.

Examples of polycrystalline ammonium polymers, -; 25 as resin remedies are found in U.S. Patent No. 3,582,461.

* · *, 'Patent 3 582 461 discloses water-soluble dicyanide; use of amide-formaldehyde condensates to prevent pitch * '' from being deposited on machines used in pulp and papermaking processes. The present invention utilizes I | | : Acidic colloids insoluble in water.

: Examples of attempts to combat pitch with other types of compounds and methods are found in U.S. Patents No. 3,812,055, 3,895,164, 3,896,046, 3,992,249, 35,431,390.

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Zirconium cabbages have also been used in the control of resin. See. e.g., U.S. Patent No. 4,950,361.

The melamine-formaldehyde-type polymers being processed are widely used in water treatment, especially for spray painting booths. See. e.g., U.S. Patent Nos. 4,656,059, 4,629,572, 4,935,149, and 5,068,279.

However, the use of melamine-formaldehyde-type polymers to combat resin and adhesive deposits is not known or has been proposed in the prior art.

As mentioned above, the present invention relates to the prevention and / or control of pitch and adhesives in papermaking. When the resin is defined as a material comprising naturally occurring resinous materials and rubbers released during the sorting, heating and grinding processes used in papermaking, the adhesives are defined as synthetic additives that enter into the raw materials of the paper. More specifically, adhesives are defined as adhesive precipitates formed from organic materials used in the re-treatment of paper and board: which are typically fed to a papermaking machine in a mixture with recycled fibers. "Infectious agent" - »»,; The reason for this designation is that the precipitates formed adhere to wires, felts, and other parts of the papermaking machine.

Adhesives form a mixture of a variety of materials, from melt-sensitive and pressure-sensitive adhesives to binders and coatings for printing inks or wet film resins. Examples of polymers include e.g. polyethylenes, polybutadiene-styrenes, polyvinylacetates and ,,,: polyacrylates.

SUMMARY OF THE INVENTION The present invention relates to the prevention of the precipitation of pitch 35 and adhesives on pulp and / or 6115476 papermaking machines, in particular the wet end of a papermaking machine, and the removal of pitch and adhesives from said machines. an effective amount of the named melamine-formaldehyde-type polymer in a pulp slurry or 5 paper blend ratio.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing pitch deposition on pulp and papermaking means or machines. The method is characterized in that an effective amount of a melamine-formaldehyde-type polymer is added to the blend, pulp or papermaking stream containing the resin in contact with said means or machines, wherein said melamine-formaldehyde-type polymer comprises (a) melamine or a substituted melamine and (b) a compound of the following formula

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R 1 -C 2 -R 2 wherein R 1 and R 2, which may be the same or different, are selected from: * · H and C 1-4 straight or branched alkyl groups.

The invention also relates to a method for preventing the deposition of adhesives on recycled pulp and paper making devices or machines. The process is characterized in that an effective amount of a melamine-formaldehyde-type polymer is added to the recycled fiber blend, pulp or papermaking stream containing adhesives in contact with said means or machines. said melamine-formaldehyde type, ··. the polymer comprises (a) melamine or substituted melamine and (b) a compound of the following formula

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Wherein R 1 and R 2, which may be the same or different, are selected from the group consisting of H and straight or branched C 1-4 alkyl groups.

An effective amount of a melamine-formal-5 dehyde type polymer must be used. The melamine-formaldehyde-type polymer used in the present invention is a polymer comprising (a) melamine or substituted melamine and (b) a compound of the following formula R 10 -C-R 2 wherein R 1 and R 2, which may be the same or different, are selected from H and C 1-4 straight or branched alkyl groups. Preferred compounds of (b) include aldehydes, of which methanal (formaldehyde), ethanal and propanal are particularly preferred; the most preferred aldehyde is formaldehyde. Melamine-formaldehyde-type polymers of the present invention may also contain moderate amounts of other ingredients such as urea and / or dicyandiamide.

However, despite the presence of other ingredients, the molar ratio of component (a) to component (b) is in the range of about 1: 1 to about 1: 6 and the preferred ratio is about 1: 1 to 1: 3. The most preferred molar ratio is about 1 molar; list of melamine or its derivative and about 2-2.5 mol- * 25 list of aldehyde. The most preferred polymer is thus prepared from melamine and formaldehyde such that the molar ratio of melamine to formaldehyde is from about 1: 2 to about 1: 2.5.

The melamine-formaldehyde polymers being processed are insoluble in water. They are thus used in the preferred I (30 min in acidic solutions in which the melamine polymer is stable), suspended in a finely divided colloid.

Calgon's product CA-289 having a pH of about 1.6 to about 2.1 is an example of a preferred form. This product contains 8% active melamine-formaldehyde polymer in an acidic aqueous solution. Any acid may be used in the preparation of the acid melamine-aldehyde suspension, but hydrochloric acid is preferred. Other stabilizing agents such as alcohols may be used.

The percentage by weight of active melamine polymer in the stabilized (acidic) suspension or solution should be in the range of about 0.1 to about 20%, preferably about 1 to about 15%, and most preferably about 4 to about 12%, for cost and product stability reasons. The pH must be low enough to keep the melamine-aldehyde-type polymer as a finely divided, colloidal suspension.

The molecular weight of the melamine-aldehyde-type polymer is not critical. However, the preferred molecular weight range is from about 500 to about 50,000 and the most preferred molecular weight range is from about 500 to about 5,000. As noted above, suitable melamine-aldehyde-type polymers are commercially available from Calgon Corporation under the trademarks CA-289 and WT-2511. These products have a molecular weight of about 2,200.

Paper mixing, paper making! an effective amount of a polyamine-type melamine-formaldehyde type must be added or maintained to the recycled fiber stream. The melamine polymer interacts with the resin or adhesives contained in such streams; * 'By preventing resin or adhesive deposits and / or • removing existing resin or adhesive deposits from the surface of the papermaking means. Herein, the patent application; ; as used herein, the term "effective amount" means honey; ; the amount of the laminin-formaldehyde-type polymer that achieves the desired inhibition or removal of the resin or adhesive in the designated system.

The melamine polymer may be added intermittently or continuously to the papermaking stream to be treated: a preferred dose of at least about 0.00454 kg (about 0.1 lb) of polymer per ton of dry fiber based on the active polymer. More preferably, the dosage is maintained in the range of about 35, 182 to about 4.54 kg / tonne (about 0.40 to about 10.0 pounds / ton). The melamine-formaldehyde-type polymer may be added at any convenient point, but is preferably added so that contact between the melamine-formaldehyde-type polymer and the resin or tackifier is maximized. The melamine-formaldehyde-5 type polymer can be added, for example, to brown liquor washers, thickeners, thick mass types or machine dilution types. Can also be added in many places.

eXAMPLES

Example 1 - Tests at the Paper Mill - Resin Jet

Calgon product CA-289 was fed to a small storage shed placed after the non-brown pulp slurry type at a softwood bleached sulphate pulp mill. Fresh 15 wood chips were used in the experiment. After processing, the stock was optionally fed through a screening plant to the bleaching plant.

The feed ratio was in the range of 0.908 to 4.54 kg (2 to 10 pounds) of 8 wt.% Active polymer per ton of blend. This corresponds to a feed ratio of about 0.073 to about 20 0.4 kg (about 0.16 to about 0.8 pounds) per ton of active polymer.

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Visually observing the sorting plant and the swirl purifiers in the bleach during the experiment could 'detect that they were practically non-existent.' · 25 pitches at all. In addition, pulp dyeing experiments showed> 'f that the amount of loose resin in the system, i.e. the amount of colloidal and loose, encapsulated resin, had significantly decreased. The amount of resin precipitated in the screening plant; , * decreased slightly (8%) after the experiment.

The Uhle boxes of the press section of the papermaking machine were cleaned one day before and one day after the experiment with colloidal: melamine formaldehyde. No resin or scale deposits were observed in the Uhle boxes. This treatment replaces the powerful AZC program.

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Example 2 - Office Mixed Waste - Control of Infectious Agents

The acidic melamine-formaldehyde colloid sold by Calgon Corporation was fed into a recycled fiber blend of office blend waste containing 3% by weight of fibers, deinking chemicals, printing ink, and bleach. The dose of polymer calculated from the active polymer was 0.295 kg (0.65 lb) / ton. Labo-10 laboratory sheets were then prepared from treated and untreated mixture ratios. Untreated laboratory sheets contained large sticky particles adhered to fibers. The treated laboratory sheets contained smaller, non-sticky particles with less fiber adherence. These experiments demonstrate the ability of the polymer to inhibit agglomeration of the adhesive-adhesive particles. These experiments also demonstrate the ability of CA-289 polymer to keep the surface of the adhesives non-stick.

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Claims (8)

1. A method for preventing the deposition of resin on pulp and paper making devices or machines, characterized in that a resin composition, stock or paper making stream containing resin in contact with said devices or machines is applied. effective amount of a melamine-formaldehyde-type polymer, said melamine-formaldehyde-type polymer comprising (a) melamine or substituted melamine and (b) a compound of the formula 0 Rx - C - r2 wherein R 1 and R be the same or different, are selected from the group H and linear or branched C 1-4 alkyl groups. Process according to claim 1, characterized in that b) is formaldehyde. 3. A method according to claim 1, characterized in that the mole ratio a): b) is about 1: 1: 1 - about 1: 6. *; · Method according to claim 2, characterized in - *. characterized in that the mole ratio a): b) is about ·: 1: 1 - about 1: 6. • <· 25 5. A method for preventing deposition of ♦ · M sticky substances on recycled fiber pulp and paper making devices or machines, characterized in that a recyclable, stock or: paper making stream of recycled fiber containing 30 substances in contact with said devices: or machines, an effective amount of a melamine-formaldehyde-type polymer, wherein said melamine-formaldehyde-type polymer comprises (a) melamine or substituted *; melamine and (b) a compound of the formula R 1 - C - R 2 wherein R 1 and R 2, which may be the same or different, are selected from the group H and linear or branched C 1-4 alkyl groups. 6. A process according to claim 5, characterized in that b) is formaldehyde. 7. A process according to claim 5, characterized in that the mole ratio a): b) is about 1: 1 - about 1: 6. 8. A method according to claim 6, characterized in that the molar ratio a): b) is about 1: 1 - about 1: 6. »· •» • 1