MXPA97003794A - Processes to reduce the contamination of licorescelulosi - Google Patents

Abstract

The present invention relates to a process for reducing contamination in a cellulosic liquor due to a colloidal sticky material derived from the pulping or de-inking of the cellulosic material, the process comprises mixing the collecting particles with a liquor characterized in that the collecting particles are polymer particles provided as an emulsion of the polymeric particles in water and formed of a monomeric mixture insoluble to water comprising: a) at least 20% by weight of the hydrophobic monomer having a solubility in water below 5 g / 100 cc; at least 10% by weight of a hydrophobic ionizable monomer that is preferably soluble in the monomer mixture when substantially un-ionized but is preferably soluble in water when ionized; c) from 0 to 50% by weight of the non-ionizable hydrophilic monomer which it is preferably soluble in the monomer and having a solubility in water above 5 g / 100 cc, and d) from 0.05 to 10% of the entanglement agent, and in which the proportions of a, b, c and d are such that an aqueous composition, formed by mixing 35 (weight of the dry polymer) of the emulsion in water with an alkaline acid. to ionize the monomer (b) is a fluid composition that contains the polymer in a particulate form dilates

Description

PROCESSES TO REDUCE THE CONTAMINATION OF CELLULOSIC LIQUORS DESCRIPTION OF THE INVENTION This invention relates to the minimization of the "stickiness" problems associated with cellulose liquors in papermaking and deinking processes. It is well known that paper-making liquors, including de-inking liquors, tend to become contaminated with a colloidal hydrophobic material, which has a tendency to aggregate and be deposited as sticky waste. These residues can be deposited in an apparatus used to handle the liquor and / or the production of liquor paper. The stickiness can originate from the operation of the original pulp formation and is due either to a sticky material naturally in the fibers that are formed in the pulp or can be generated by the interaction between the fibers and chemicals used in the formation process of the pulp. Alternatively, the tackiness can be caused by the deinking process. For example, deinking often involves exposing the cellulosic material to alkaline conditions and this can generate the material with a colloidal hydrophobic tack. Various treatments are known to minimize tackiness. For example, it is known to treat a coarse raw material with bentonite for this purpose. Bentonite is a material that occurs naturally with a variable quality. It will be desirable to be able to achieve the reduction of tack contamination using a synthetic material of a controllable quality. It will also be desirable to obtain better results than those obtainable using bentonite. The use of various polymers is also known.

Examples are the coagulants with a low molecular weight and the polymers mentioned in US Pat. Nos. 5,433,824, 5,368,694, 5,292,403, 524,649 and 4184912 and EP-A-280445 and 464993. There is a need for a method for controlling reproducible tackiness. , of effective cost, improved and different. According to the invention, we reduce the contamination in a cellulose liquor due to a colloidal tack material derived from the pulping or de-inking of the cellulosic material by a process that comprises mixing the collecting particles with the liquor, and in this process the particles collectors are polymeric particles provided as an emulsion of the polymeric particles in water, wherein the polymer is formed from a monomeric mixture insoluble to water, comprising: a) at least 20% by weight of the hydrophobic monomer having a solubility in water below from Sg / 100 ce at 20 ° C. b) at least 10% by weight of the hydrophilic ionizable monomer that is preferably soluble in the monomer mixture, when substantially not ionized but preferably soluble in water, when ionized. c) from 0 to 50% by weight of a non-ionizable hydrophilic monomer which is preferably soluble in the monomer mixture and which has a solubility in water above 5 g / 100 ce at 20 ° C. d) from 0.05 to 10% of an entanglement agent, and that the proportions of a, b, c and d are such as an aqueous composition, formed by mixing 3% (dry weight polymer) of the emulsion in water with an acid or alkali for ionizing the monomer (b), is a fluid composition containing the polymer in a dilated particulate form. The deinking processes employing these emulsions, and certain novel emulsions are described in the application (reference 60/3493.), Still filed as of the date hereof.

The pH of the liquor during the process (that is, at the time of adding the emulsion and collecting the colloidal particles in the polymer particles) is often almost neutral (for example, a pH around 6 to 8) but in some examples, the liquor may be more acidic (for example, a pH below 4 or still a pH 3) or may be alkaline (for example a pH of up to 9 or still a pH of 10.5). An advantage of the invention is thatBy properly selecting the polymer components, it is possible to optimize the polymer for any existing pH condition during the process. The polymer will substantially retain its particulate form during the process, so that the tackiness can be collected on the particles. Therefore, the proportions of the monomers will be selected so that this is achieved. In particular, sufficient entanglement agent will be included to ensure that the nature of the particulate is substantially maintained. If the amount of the entanglement agent is quite low, the polymer can be completely dissolved in use and this is undesirable. It can be estimated whether the particles substantially retain their particulate form or not by observing their viscosity.

Preferably, the polymer emulsion is such that, when mixed with water to provide 3% of the composition and adjusted to a pH prevailing in the process, this composition will provide a viscosity below 50,000, preferably below 10,000 and more preferably down 2,000 cps measured with a Brookfield RVT Viscometer. Generally, the viscosity is between 50 and 1000 cps. However, in some processes, it is possible to use polymers that will provide viscosities above 100,000 cps as long as the polymer is added as a composition having such a concentration that it can be conveniently used in the process. The polymer preferably is such that it has a particle size, at a pH that prevails in the process, below 15 μm and more preferably below 10 μ, with the best results generally obtained when the particle size is below of 5 μm, especially below 3 μm. It is generally above 0.1 μm and preferably above 0.3 μm. The polymer particles are dilated as units to ionize the monomer (b). The emulsion is generally made by polymerizing the emulsion at a pH at which the monomer units (b) substantially do not ionize and in this state the polymer preferably has a particle size below 0.5 μm, more preferably below of 0.3 μm. It is generally above 0.02 μm, and generally above 0.05 μm. It is generally preferred that, at a pH that prevails in the process, the particle size is generally at least 1.5 times, and often at least 2.5 times in the undilated particle size. Normally, it is not greater than 5 or 8 times the undilated particle size but useful results can still be obtained with higher degrees of dilation, for example up to 15 or 20 times. All particle sizes defined herein are the particle size (ie, diameter) determined by a laser light scattering of 95% by weight of the particles. So typically the particles can dilate from a size of 50 to 300 nm to a size of 300 to 1500 nm. It is necessary to include sufficient entanglement agent to avoid total solubilization of the particles and in particular to control the size of particle in use to the desired size, and to minimize the increase in viscosity. Generally, the amount of the entanglement agent is at least 0.1% and usually at least 0.2% (2,000 ppm) by weight. Such polymers are useful especially when the process is carried out at a substantially neutral pH so that the monomer (b9 only becomes partially ionized) For example, the process can be carried out at a pH of about 6.5 to 8 using a polymer having a desired particle size under these conditions but which is further expanded if the pH is higher (e.g., a pH of 10) or lower (e.g., a pH of 3.) However, preferably, the polymer it is prepared using the proportions of an entanglement agent and other monomers such that it only expands to 15 or 20 times its diameter without expansion, preferably up to 8 times its undilated diameter, when it is completely ionized. process without risk of the polymer dissolving or also providing a high viscosity if the process pH is particularly high or particularly low. They are obtained by using higher amounts of the entanglement agent, usually at least 0.5% and typically 1 or 2% to 5% by weight. The amount of the entanglement agent and the proportions of other monomers are selected such that the polymer has a relatively low required expansion rate and a relatively low required viscosity for the composition when exposed to sufficient acid or alkali to achieve maximum polymer expansion potential (for example, a pH of 3 or a pH of 10). The polymeric emulsion is preferably made by a conventional polymerization of the oil-in-water emulsion of the monomer mixture at a pH in which the monomer (b) is substantially un-ionized and the resulting polymer is substantially un-ionized and undilated, so that the monomer (b) is preferably soluble in the monomer mixture at this pH. However, by adjusting the pH of the final composition to a pH at which the monomer will be ionized, the polymer expands. The monomers are usually all ethylenically unsaturated monomers. By referring preferably to monomers soluble in the monomer mixture we mean that the monomers are dissolved in the oily phase of the oil-in-water emulsion polymerization mixture, preferably it is in the sufficient aqueous phase that there is substantially no polymerization of the polymer. monomer in the aqueous phase. The oil-in-water emulsion polymerization is carried out at a polymerization pH, which is the pH at which the hydrophilic ionizable monomer is not ionized and preferably is soluble in the monomer mixture and typically this is in the range of to 11. When the monomer (b) is anionic (generally a carboxylic monomer) the pH of the polymerization will normally be acidic, typically around 2 to 5 or 6, and the resulting polymer will expand when the pH subsequently adjusted to be alkaline, typically above 7, for example, 7.5 or 8 to 10. When the monomer (b) is cationic (generally an amine monomer) the polymerization pH is generally alkaline, typically from 8 to 10, often around 9, and the polymer can then be brought into its fully expanded state in an acidic medium typically from 4 to 6. The amount of the hydrophobic monomer (a) is generally from 20 to 80%. Normally it is above 40%. It is usually below 70% and often below 60%. Often an amount of about 50% is preferred. The amount of hydrophilic ionizable monomer (b) it is generally from 10 to 80% by weight. The amount is typically at least 20% and usually at least 30%, and often at least 40%. In case it is included enough it can be difficult to select a monomer (a) which will avoid the monomer (b) which dissolves in the aqueous phase, so that generally the amount of monomer b is below 60%. Often quantities of around 50% are preferred. The monomer (c) is optional but may be included, if desired, to improve the hydrophilic properties without increasing the pH sensitivity. The amount is usually below 30%, usually below 10% and generally the monomer is omitted. The amount of the interleaver is generally 0.1%. The amount depends on the relative proportions of the monomers (a), (b) and (c). Increasing the amount of (b) tends to increase the amount of interlacer (d) that is required, in order to resist excess dilation. Conversely, increasing the amount of the momer (a) tends to reduce the amount of the interleaver (d) that is required. The amount of preference is sufficiently high that substantially the polymer of the polymer particles can not be dissolved. So preferably the soluble fraction is below 1% as measured by the gel content. The hydrophobic monomer (a) will have a solubility in water below 5g / 100 ce at 20 ° C and this solubility is usually substantially independent of the pH of the polymerization and thus the hydrophobic monomer will generally have this low solubility value throughout the entire polymerization, for example, the pH varies from 2 to 10. Preferably the solubility of the hydrophobic monomer in water is still lower, for example below 1.5 / 100cc. The solubility of any non-ionizable hydrophilic monomer (c) is generally any value greater than the maximum solubility defined for the hydrophobic monomer and typically is above 10g / 100g at 20 ° C but is usually not higher than 200g / 100cc at 20 ° C. . These solubilities will normally be substantially pH independent. The polymerization is an addition polymerization comprising ethylenically unsaturated monomers. This generally leads to the molecular weight, in the absence of the entanglement agent, being in the range of 100,000 to 500,000 as measured by gel permeation chromatography. The hydrophobic monomer (a) can be any of the monomers conventionally used for copolymerization with the ethylenically unsaturated carboxylic monomers in a polymerization of the oil in water emulsion. So it can be selected from alkyl (meth) acrylates, styrenes, vinyl esters, acrylonitriles, associative monomers (for example, acrylic esters or allyl ethers having a pendant polyethoxy chain terminated with a hydrophobic group such as an alkyl of fatty acid or alkaryl or aralkyl) or vinyl ethers. The preferred monomer (a) is selected from styrene and meth (alkyl acrylate, wherein the alkyl groups are generally Cl to 8 but can be a fatty acid alkyl.The preferred monomer (a) is ethyl acrylate but others suitable monomers include styrene, methyl acrylate, butyl acrylate, monomer mixtures (a) can be used.The ionizable monomer (b) is usually an amine or ethylenically unsaturated carboxylic acid.The carboxylic acids are methacrylic acid, acrylic acid itaconic acid , crotonic acid, maleic acid (or anhydride) .The preferred acid is methacrylic acid.The suitable ionizable amines are dialkyl aminoalkyl or dialkylaminoalkyl methacrylates and dialkylaminoalkyl (meth) acrylamides. dimethylaminoethyl (meth) acrylates. The non-ionizable hydrophilic monomer (c) can be, for example, a hydroxyalkyl alkyl (meth) acrylate, typically hydroxyethyl (meth) acrylate. The interlayer (d) can be any polyethylenically unsaturated, oil-soluble interlayer or other suitable interleaver to cause entanglement during the polymerization of the emulsion in water. The typical materials are divinylbenzene, diallyl phthalate, and di-, tri- and tetrafunctional (meth) acrylates. The preferred material is a diallyl phthalate (DAP). The polymerization of the oil-in-water emulsion is preferably carried out in such a way that the polymer particles formed by the polymerization of the emulsion have a dry size (determined by the dispersion of the laser light) below 0.5 μm and generally below 0.3 μm and preferably above 0. 02 μm, typically 0.05 to 0.2 μm. So that at least 90% by weight, often at least 95% and preferably at least 100% by weight of the particles have such a size. The polymers of the emulsion can be made by widely conventional techniques for the polymerization of an oil-in-water emulsion suitable for making the desired particle size. Thus, the monomer mixture is typically formed and emulsified in water at the pH of the polymerization in the presence of a suitable emulsifier. The emulsifier is typically of an anionic class, preferably an ethoxylated sulfate of a fatty acid alcohol. The amount of the emulsifier is typically about 3%. Emulsification can be achieved by homogenizing the monomer mixture in water containing the emulsifier in a conventional manner. Polymerization can be initiated by typically including water-soluble initiators such as ammonium persulfate. The polymerization is preferably carried out at a temperature of at least 90 ° C. The polymerization generally continues for a period of 1 to 3 hours, if desired, the monomer can be fed into the polymerization mixture during the polymerization. The total amount of the polymer in the final polymer emulsion is generally in the range of 20 to 40% by weight. When all the monomer is in the emulsion before the polymerization, therefore, the amount of preference will be within the same range. It will be appreciated that the polymer particles have hydrophobic and hydrophilic components and can thus be related as amphipathic. It appears that the hydrophobic components of the polymeric particles can interact with the colloidal sticky materials, probably due to the hydrophobic nature of these, in order to cause the colloidal particles to be collected by the polymeric particles, thus forming the aggregates.

The formation of these aggregates may be sufficient to reduce pollution in any particular condition as they may, for example, prevent the contamination of a liquor before it is spent in the process or in some other process, where the risk of contamination may be smaller or can be reduced by some additional treatment. However, it is generally desirable to fix the added tackiness in the cellulosic fibers in the liquor or to separate the added tackiness of the liquor. When the polymer is cationic, the sticky aggregates and the polymeric particles can be sufficiently cationic to be substantive with respect to the cellulosic fibers in the liquor and can thus be fixed in the fibers without further treatment, especially when the fiber content is relatively high , for example above 0.1%. However, the substantivity of the aggregates with the fibers can be improved by incorporating the cationic polymer material into the liquor before or after adding the particulate polymeric material. This is particularly desirable when, as is normally the case, the particulate material is anionic. Instead of fixing the stickiness in the cellulose fibers in the liquor, it may be desirable to remove the tackiness of the liquor, and the removal of the collected tackiness may be promoted by adding a water-soluble coagulant or a flocculant in the liquor before, or more usually after, add the particulate polymeric material. Generally this coagulant or flocculant is counter-ionic in the particulate polymeric material. Generally the polymeric material is anionic and the coagulant or flocculant is cationic. Preferred processes according to the invention comprise using an anionic particulate polymer to collect the tackiness and a cationic coagulant of low molecular weight to fix the stickiness in the fibers or to produce the cationic tackiness, in order to promote its removal from the liquor, for example, by sedimentation or filtration or flotation. Typically, the cellulosic content of the suspension is below 25. In some examples, it may be desirable to add a flocculant, generally, a cationic flocculant, in order to further improve this removal by sedimentation, filtration or flotation. The cationic coagulants can be an inorganic coagulant, such as a polyvalent metal salt (e.g. alum) but is preferably a cationic polymeric material. Typically it has a molecular weight below 2 million and often below 1 million (measured by gel permeation chromatography). Expressed in the terms of an intrinsic viscosity (measured by a suspended level viscometer at 25 ° C in IN of buffered sodium hydroxide at a pH of 7.5) below 3dl / g and often below 1.5 dl / g. The coagulant can be any of the conventional cationic coagulants such as a polyethylene imine, a polyamine (for example a condensate of a diamine with epichlorohydrin) and polymers of an ethylenically unsaturated cationic monomer, optionally copolymerized with up to 50% of another monomer, generally acrylamide or other non-ionic monomer. Suitable cationic monomers are quaternary diallyldialkyl salts, especially diallyldimethyl ammonium chloride and dialkylaminoalkyl (meth) acrylate or acrylamide, generally as the addition of an acid or quaternary ammonium salts. An example is the quaternary salt of dimethylaminoethyl (meth) acrylate. The cationic monomer is preferably at least 80% by weight of the monomers used to form the polymer, and is generally 100%. A preferred material is DADMAC poly. If the flocculant is used, it is generally a material that has an intrinsic viscosity above 4, and often above 6 dl / g. It can be a non-ionic acrylamide or an ionic acrylamide, for example, an acrylamide copolymer with a suitable amount of sodium acrylate or one of the cationic monomers listed above. A liquor to which the invention can be applied is a washing liquor or debugger of a deinking process. The deinking processes comprise the formation of a pulp and the subjection of the pulp to a separation process whereby the ink particles are separated from the pulp, for example, by depuration or flotation. The liquor treated in the invention can be a wash liquor or scrubber that is used to remove the ink particles from the pulp (often after filtration or other separation of the ink particles from the liquor) or it can be a liquor that be drained of the de-inked pulp. The invention is of particular value in such processes, wherein the deinking pulp formation process is carried out under alkaline conditions, for example at a pH of from 8 to 10.5, often from 9 to 10.5, since these alkaline conditions they can promote the release of the colloidal tackiness of the cellulosic material.

The washing liquors of the deinking process (ie, the liquors used to wash the pulp during the process or separated from the pulp after the process) generally have a cellulosic content in a range of 0.01 to 1% by weight. When the invention is used for the treatment of such liquors, it usually removes the colloidal tackiness, with some or all of the cellulosic content, from the liquor by a flotation or sedimentation process, with the removal being promoted by the addition of a coagulant. , generally after the addition of the collecting particles. It will be noted that the invention does not extend to a deinking process as such, but mainly to a process in which the polymer particles are incorporated into the pulper or other deinking process in order to promote the removal of the ink from the ink. pulp. The ink particles in this step are non-colloidal tack. The invention is also of value for the treatment of contamination derived from the cellulosic material formed in pulp. Therefore, the polymeric material can be added during the pulping process, or more generally, a coarse raw material or a thin raw material or recycled water (ie, recycled water from the drain) can be added during papermaking. In such processes it is generally desirable to fix the tackiness and the particulate polymer in the fibers in the recycled water, the thin processing material or a coarse raw material by depending on the use of the cationic polymer particles or by the addition of the cationic coagulant before, or more generally after, of the addition of the polymer particles. When the liquor is generally 0.01 to 1%. When the liquor is a thin raw material the concentration is generally 0.2 to 2% and when the liquor is a component of a coarse raw material or a thin raw material, the concentration is generally from 1.5 to 5%. The dosage of the particulate material will normally be in the range of 1 to 50 ppm based on the total weight of the liquor or 1 to 5000 ppm, often 50 to 1000 ppm, based on the cellulosic content of the liquor. The emulsion is generally added after dilution to a polymer concentration of 0.005 to 0.5%, often 0.01 to 0.15 of the polymer. The amount of the cationic polymeric coagulant which is generally used is in the range of 1 to 200 ppm of the active polymer (based on the weight of the liquor) or 1 to 2000 ppm, often from 20 to 1000 ppm based on the cellulosic fibers .

The following are examples of the invention. EXAMPLE 1 This demonstrates the production of the polymer emulsion. The feed monomer is formed of 155 parts by weight of ethyl acrylate, 155 parts by weight of methacrylic acid and 5.9 parts by weight (about 2%) of diallyl phthalate. This feed monomer is homogenized with 310 parts by weight of water, 5.7 parts by weight of 27% of a sodium salt solution of an ethoxylated C12-16 fatty acid alcohol sulphated surfactant and 0.1 parts by weight of the agent from separation. The resulting emulsion together with a solution of 30 parts of water and 0.55 parts of ammonium persulfate are gradually fed to a solution of 360 parts of water, 5.75 parts of the surfactant, 0.1 parts of the separation agent and 0.38 parts of the ammonium persulfate during a period of about 90 minutes, while the polymerization mixture is maintained is maintained at a temperature of about one hour and then cooled. The product emulsion has a polymer content of approximately 30% by weight. If necessary, it can be filtered to remove coarse particles. The processed emulsion has a particle size range (determined by scattering of laser light) of 95% by weight of the particles around 100 nm (0.1 μm). When the emulsion is diluted with water for a solids content of 3% at a pH of 8, the particle size is at least 95% approximately 3μm and the viscosity is approximately 150 cps as measured by the Brookfield RVT Viscometer. When the process is repeated with different amounts of the interlayer, the particle size of the non-neutralized emulsion remains constant (with an approximate average of 0.1 μm) but the size of the dilated, neutralized particle varies according to the amount of interleaver, as shown in the following table, which gives the approximate average particle size at different amounts of interleaver after neutralization at a pH above 8: TABLE 1 Interleaver% 0.25 0.5 0.75 1 2 5 Dilated size (μm) 1.3 1 0.6 0.65 0.3 0.36 The polymers shown in Example 1 have high degrees of alkali expansion (generally made with 0.25% interleaver quantities and lower, are commercially available as thickeners.) Polymers that have higher amounts of entanglement are the materials Novelties Due to their low dilatation properties, they are not useful as thickeners EXAMPLE 2 With the f In order to demonstrate the ability of the polymeric emulsion to remove stickiness, a laboratory experiment was carried out using a polymer emulsion according to Example 1 (employing 1.9% DAP) in a laboratory experiment. The cellulosic fiber suspension was produced to generate a thin raw material of paper pulp. The thin raw material comprises only the fiber fraction with 2% of the raw material classified by its consistency. The filtrate contained fine fibrous components and a filler, both having dimensions less than 75 μm, as well as, the dissolved concomitant and the colloidal material that includes the tackiness. The experiment was carried out at a natural pH and at room temperature. The emulsion was added as a dilute suspension (0.3% of the polymer concentration) to a coarse raw material and stirred for five minutes, after which a solution of a cationic polymeric coagulant was added and stirred for five minutes before the separation of the components of the raw material by filtration through a dynamic drainage vessel. The cationic polymeric coagulant that was used was a polydiallyldimethyl ammonium chloride solution. The filtration had the effect of separating the fiber fraction from the filtrate containing the fine fibrous components, the filler and the colloidal and the dissolved material including the tackifying components. The turbidity of this filtrate was measured (with the results expressed in FTU). The filtrate was then centrifuged to separate the fine fibrous components and the filling of the colloidal and dissolved material and the centered element containing the colloidal and dissolved material was estimated by the Total Organic Carbon (with the results expressed as TOC in mg / l). The results are described in Table 1, in which the dosages of the emulsion and the coagulant solution are expressed as percentages based on the fiber. TABLE 1 Coagulant Emulsion Turbidity: TOC (FTU) (mg / l) 0 0 155 1570 1 0 128 1530 0 0 0.8 138 1560 TABLE 1 (Continued) Coagulating Emulsion Turbidity TOC 0.6 0.8 88 1500 1. 0 0.8 73 1490 1. 6 0.8 82 1485 0 1.6 122 1480 0. 6 1.6 90 1450 1. 0 1.6 70 1480 1. 6 1.6 80 1420 This clearly demonstrates the benefit of including the emulsion defined in the process. EXAMPLE 3 This is an example of a process of deinking the recycled pulp carried out in a normal way by forming the pulp with a high consistency followed by screening and debugging the coarse raw material followed by flotation of the deinking to provide a rejected fraction containing the ink and a subflow, the thin raw material is screened and purified and de-inked by washing. The subflow of the deinking by flotation and the clean thin raw material are passed, through a centrifugation step, at a point where, in the invention, the emulsion is added and the treated liquor is then mixed with a de-inking subflow by washing . The resulting mixed liquor containing the emulsion particles is then dosed with a cationic polymeric coagulant (a polymer of a poly-DADMAC solution) and subsequently with a flocculant with a high molecular weight, and then subjected to a clarification of dissolved air . The turbidity of the accepted fraction of the dissolved air clarifier was measured. The results are shown in Table 2 TABLE 2 Particle Coagulant Flocculant Clarifier Cationic collector (ppm) Accept (ppm) (ppm) (FTU) 0 3.4 6.1 18.3 1.7 3.4 6.1 18.1 1.7 3.4 6.1 17.0 10.1 4.5 6.1 16.9 10.1 4.5 4.5 17.3 8.1 4.5 4.5 17.7 Again, the lower turbidity value obtained when the emulsion of Example 1 is used to demonstrate the improved performance. EXAMPLE 4 A milling experiment employing the general process described in Example 3 was carried out and it was found that, when quantities of the same cationic and flocculating coagulant are widely employed, the additional use of the emulsion of Example 1 was able to provide a significant reduction in the percentage of TOC.

Claims (12)

1. NOVELTY OF THE INVENTION Having described the invention as above, we consider what is contained in the following: CLAIMS 1. A process to reduce contamination in a cellulose liquor due to a colloidal sticky material derived from the formation of pulp or deinking of the material cellulosic, the process comprises mixing the collecting particles with a liquor characterized in that the collecting particles are polymer particles provided as an emulsion of the polymer particles in water and formed of a water-insoluble monomer mixture comprising: a) at least 20% by weight of the hydrophobic monomer having a solubility in water below 5 g / lOOcc; b) at least 10% by weight of a hydrophobic ionizable monomer that is preferably soluble in the monomer mixture when substantially not ionized but preferably soluble in water when ionized; c) from 0 to 50% by weight of the non-ionizable hydrophilic monomer which is preferably soluble in the monomer and having a solubility in water above 5 g / 100 cc, and d) from 0.05 to 10% of the crosslinking agent, and wherein the proportions of a, b, c and d are such that an aqueous composition formed by mixing (weight of the dry polymer) of the emulsion in water with an acid or alkali to ionize the monomer (b) is a fluid composition which contains the polymer in a dilated particulate form.
2. 2. A process according to claim 1, wherein the liquor is wash water from a deinking process.
3. 3. A process according to claim 1, wherein the liquor is a coarse raw material, a thin raw material or water recycled from a papermaking process.
4. 4. A process according to any of the preceding claims in which a water-soluble coagulant or flocculant is added to the liquor.
5. A process according to any of the preceding claims in which the polymer particles are anionic and the water-soluble cationic coagulant is subsequently added to the liquor.
6. 6. A process according to claim 5, in which tackiness is collected with the polymer particles and removed from the liquor by sedimentation, filtration or flotation.
7. A process according to any of claims 4 to 6 in which a coagulant is added to the liquor and the coagulant is selected from polyamines, polyethylene imines and copolymers of 80 to 100% of the ethylenically unsaturated cationic monomer, preferably DADMAC , with 0 to 205 of the ethylenically unsaturated nonionic monomer.
8. A process according to any of the preceding claims in which the emulsion has an undilated particle size of 0.02 to 0.5 μm, and a particle size at the pH prevailing in the pulp which is at least 1.5 times the size of the the particle not dilated and is from 0.1 to 5 μm.
9. 9. A process according to any of the preceding claims in which the polymeric emulsion provides a viscosity, at the pH prevailing in the pulp, of 10,000 cps measured by a Brookfield RVT viscometer.
10. 10. A process according to any of the preceding claims in which the amount of the entanglement agent is at least 0.5% by weight.
11. 11. A process according to any of the preceding claims in which the amount of monomer (a) is from 40 to 70%, the amount of monomer (b) is from 30 to 60%, and the amount of the monomer (c) ) is from 0 to 30% and each of the monomers (a), (b), and (c) are ethylenically unsaturated.
12. 12. A process according to any of the preceding claims in which the monomer (a) is selected from alkyl (meth) acrylates, styrenes, vinyl esters, acrylonitriles, associative ethylenically unsaturated monomers and vinyl ethers, the monomer ( b) is selected from ethylenically unsaturated carboxylic acids and amines, the monomer (c) is a hydroxyalkyl (meth) acrylate and the monomer (d) is an oil-soluble polyethylenically unsaturated monomer.