Classifications

• • D—TEXTILES; PAPER
  • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
  • D21C—PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
  • D21C9/00—After-treatment of cellulose pulp, e.g. of wood pulp, or cotton linters ; Treatment of dilute or dewatered pulp or process improvement taking place after obtaining the raw cellulosic material and not provided for elsewhere
  • D21C9/08—Removal of fats, resins, pitch or waxes; Chemical or physical purification, i.e. refining, of crude cellulose by removing non-cellulosic contaminants, optionally combined with bleaching
  • D21C9/086—Removal of fats, resins, pitch or waxes; Chemical or physical purification, i.e. refining, of crude cellulose by removing non-cellulosic contaminants, optionally combined with bleaching with organic compounds or compositions comprising organic compounds

Definitions

• the present invention concerns compositons and methods for reducing or preventing the deposition of pitch-like resin during the papermaking process.
• the present invention concerns the addition of from 0.5 to 20 parts per million by weight of polyampholyte to the papermaking slurry in order to prevent or reduce pitch-like resin deposits.
• Talc has also been used to control pitch by adsorbing dispersed resin particles on the faces of the talc platelets; but talc creates handling problems and requires expensive automatic feeding systems.
• Dispersants, or surface active agents have been utilized to stabilize, solubilize, and redisperse resin deposits. However, some dispersants are toxic; and large doses can result in extensive detachment of existing deposits, with severe consequences downstream.
• Papermaker's alum usually together with sodium hydroxide or sodium aluminate, has been used to flocculate the dispersed resin particles in papermaking furnishes. However, alum does not completely eliminate pitch deposition problems, and in high concentrations causes a loss of drainage and retention.
• the physical distribution of wood resin in aqueous pulp suspensions or slurries has been found to vary.
• the resin occurs (1) on the surfaces of fibers and fines, sometimes as a thin, generalized film, but more often as discrete patches or droplets; (2) inside parenchyma cells; and (3) in colloidal form suspended freely among the fibers in the process liquid.
• the intense pressure of the nips results in a transfer of a certain amount of resin from the surfaces of the fibers to those of the felts, and some parenchyma cells may also be ruptured. About 10% of the resin in the pulp is transferred to the felt where it can cause plugging of the pores or deposit subsequently during the felt dewatering process on the Uhle box lips.
• Dispersed or colloidal resin deposits occur when hydrodynamic shear is sufficient to overcome naturally-occurring electrical and steric repulsion between the resin particles and a surface on which they might deposit. Deposition of dispersed resin is also promoted by the different processes of evaporation, creaming and coalescence, and foam formation and collapse.
• the problems of pitch-like resin deposition during the papermaking process described above are reduced or prevented by incorporating in a pitch-like-resin-containing paper pulp slurry from 0.5 to 20 parts per million by weight of a polymer or copolymer of the formula: where DMDAAX ⁇ is a polymer unit resulting from monomeric dimethyldiallylammonium X ⁇ ; DEDAAX is a polymer unit resulting from monomeric diethyldiallylammonium X ⁇ ; X is an anion; M ⁇ is hydrogen; ammonium; sodium; or potassium; and k and 1 together total 50 weight percent, and m and n together total 50 weight percent; while k is from 45 to 48 weight percent and 1 is from 2 to 5 weight percent; and while m is from 45 to 50 weight percent and n is from 0 to 5 weight percent; said polyampholyte having a molecular weight greater than 1 x 10 .
• Any anion (counterion) compatible with the papermaking process may be employed, and chloride is preferred.
• Other acceptable anions include acetate, citrate, formate, glycolate, lactate, nitrate, oxalate, propionate, sulfate, and other halides, for example.
• Preferred polymer compositions of Formula I are (1) where X 9 is chloro; and k is 47.5 weight percent, 1 is 2.5 weight percent, m is 47.64 weight percent, and n is 2.36 weight percent, giving a polyampholyte having repeating units of dimethyldiallylammonium chloride (DMDAAC), diethyldiallylammonium chloride (DEDAAC), acrylamide (AM), and acrylic acid (AA); and (2) where X ⁇ is chloro; and k is 47.5 weight percent, 1 is 2.5 weight percent, m is 50 weight percent, and n is 0 weight percent, giving a polyampholyte having repeating units of dimethyldiallylammonium chloride (DMDAAC), diethyldiallylammonium chloride (DEDAAC), and acrylamide (AM).
• DMDAAC dimethyldiallylammonium chloride
• DEDAAC diethyldiallylammonium chloride
• AM acrylamide
• acrylic acid acrylic acid
• AA
• the pitch control additives of the present invention may be incorporated into the pulp slurry at any stage of the pulping operation, including prior to or after digestion, during beating, in the stock-chest, or in the headbox of the papermaking machine.
• the pitch control additives may also be added to the whitewater being recirculated for pulp slurry dilution prior to the headbox. This is the preferred point of addition.
• the amount of pitch control additive incorporated into the pulp slurry to be treated will be between 0.5 and 20 parts per million by weight, based on the total weight of pulp slurry treated. This amount of incorporated additive will correspond approximately to from 0.01 to 0.1% by weight, based on the weight of pulp solids.
• the polymer additives of the present invention are readily soluble in turbulent water, and are desirably prepared as 0.25% solutions by pouring into turbulent water with continued moderate agitation for approximately 10 minutes. These solutions are then conveniently metered to a pulp slurry in the treatment amounts described above.
• the polymer additives may be added neat, that is, at the percent solids concentration in which they are usually prepared and used: about 35 to 55% solids.
• This example illustrates the effectiveness of the pitch control additives of the present invention in reducing pitch deposits by attaching pitch colloidal particles to wood fibers and fines, measured as a percent count reduction from blank.
• the pulp slurry involved was a combination of pulp from four pulping systems: kraft, groundwood, thermo-mechanical, and cold soda.
• each polymer was attached to fibers by using a Britt jar. Once the Britt jar propeller was set in motion (200 rpm), headbox stock (500 ml) was added to the jar. Because of pitch count variability, samples were done by buckets. The count for each sample was logged against the count for the blank from the same bucket. A 0.1% solution of each test polymer was made, and polymer treatment in a 1 ppm - 20 ppm dosage range was added in different samples. After mixing for a specific time period (2 minutes), filtrate was withdrawn from the bottom of the jar and filtered through steel wool. The number of colloidal particles per unit volume present in the filtrate was counted by using a microscope and hemacytometer. The particles were counted within ten .05 mm x .05 mm x .1 mm unit volumes. The count was averaged per one unit. The effectiveness of a polymer was evaluated by determining the percent count reduction from the blank.

Landscapes

• Life Sciences & Earth Sciences (AREA)
• Engineering & Computer Science (AREA)
• Wood Science & Technology (AREA)
• Paper (AREA)
• Undergarments, Swaddling Clothes, Handkerchiefs Or Underwear Materials (AREA)
• Orthopedics, Nursing, And Contraception (AREA)
• External Artificial Organs (AREA)

Applications Claiming Priority (2)

Publications (1)

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Family Applications (1)

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Cited By (18)

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Citations (2)

• 1982
  • 1982-02-11 AU AU80400/82A patent/AU8040082A/en not_active Abandoned
  • 1982-02-12 FI FI820476A patent/FI820476L/fi not_active Application Discontinuation
  • 1982-02-15 EP EP82400267A patent/EP0058622A1/fr not_active Withdrawn
  • 1982-02-16 DK DK66382A patent/DK66382A/da not_active Application Discontinuation
  • 1982-02-16 NO NO820466A patent/NO820466L/no unknown
  • 1982-02-17 JP JP57022942A patent/JPS57149592A/ja active Pending

Patent Citations (2)

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