POLYMER COMPOSITION FOR IMPROVED RETENTION, DRAINAGE AND FORMATION IN PAPERMAKING

Abstract: The invention relates to a cationic polymer composition for improving the retention, drainage, and formation properties of paper and paperboard products. The cationic polymer composition comprises at least two coagulants where the first coagulant is a polynucleate aluminum silicate - sulphate compound containing a chloride molecule (PASS-C) and the second coagulant is selected from the group consisting of a polydadmac, a polyamine, a polyethylene imine, a polycyanogunidine, and a copolymer containing a DMDAAC. These two coagulants may be blended together and can be added to the pulp stock or slurry anywhere in the paper machine wet-end as the polymer composition is not shear-sensitive. The ratios of the two coagulants in the blend may range from about 1:1 to 1:4 and from about 1:1 to about 4:1. The polymer composition can be used alone in the paper making process or it can be used in combination with a flocculant (polyacrylamide) to enhance the dewatering efficiency. The flocculant is added after the shearing stages and after the addition of the polymer composition.

Description: POLYMER COMPOSITION FOR IMPROVED RETENTION, DRAINAGE AND FORMATION IN PAPERMAKING BACKGROUND OF THE INVENTION 1. Field Of The Invention The present invention relates to a cationic polymer composition comprising two coagulants one of which is a polyaluminum chloride silicate (PASS-C) and the other being selected from the group consisting of a polydadmac, a polyamine, a polyethylene imine, a polycyanogunidine, and a copolymer containing DMDAAC, and to a method using the composition for making paper or paperboard having improved properties in the areas of drainage, retention, and formation. 2. Description Of The Background Art In the production of paper or paperboard from a dilute aqueous cellulosic furnish improvements in retention and drainage and in the formation properties of the final paper or paperboard sheet are particularly desirable. It is well known by those skilled in the art that these parameters are frequently in conflict with each other. For example, if the cellulosic fibers of the aqueous cellulosic furnish are flocculated effectively to larger floes, retention of, for example, fiber fines and filler is generally good and can result in a porous structure yielding generally good drainage; however, formation is poor. In this light, conventional practice has resulted in those skilled in the art selecting one or more additives to improve the production of paper or paperboard according to the parameters that are most important to achieve. Alternatively, if the cellulosic fibers are flocculated to a lesser degree, drainage and retention are less satisfactory; however, formation is improved. Further, drainage and retention are often in conflict with each other when, for example, increased production of paper or paperboard is desired over the need for retention of, such as for example, fillers and the like. Retention is believed to be a function of different mechanisms such as filtration by mechanical entrainment, electrostatic attraction and bridging between aqueous cellulosic fibers and fillers. Because both cellulose and many common fillers are electronegative, they are mutually repellent and, in the absence of a retention aid, the only factor tending to enhance retention is mechanical entrainment. Drainage relates to the rate at which free water is released from a sheet as it is being formed. Thus, it will be appreciated that drainage aids improve the overall efficiency of dewatering in the production of paper or paperboard. Formation relates to the formation of the paper or paperboard sheet produced from the paper making process. Formation is generally evaluated by the variance in light transmission within a paper sheet. A high variance is indicative of poor formation. It is generally well known by those skilled in the art that as the retention level increases, the level of formation generally decreases from good formation to poor formation. A variety of compositions and processes have been proposed to improve retention, drainage, or formation in the paper making process. U.S. Patents Nos . 5,501,772; 5,501,773; 5,567,277; and 5,647,956 disclose a composition comprising an aqueous cellulosic furnish, a high molecular weight cationic polymer, and a modified lignin with a ratio of the cationic polymer to the modified lignin being from 10:1 to 1:10 on an active basis and a process employing this composition for making paper or paperboard having improved drainage, retention, and formation properties. U.S. Patent No. 5,149,400 discloses a novel polynucleate aluminum hydroxy silicate-sulphate compound (PASS) , which is especially useful as a drainage and retention aid and size promoter for use in paper making. A process for manufacturing this product is disclosed and claimed in U.S. Patent No. 5,296,213. U.S. Patent No. 5,149,400 teaches that it has been found that PASS can be used as a replacement for alum (aluminum sulphate) used as a draining-retention aid in acidic paper making processes and as a draining-retention aid and size promoter in neutral and alkaline paper making processes, even though alum itself cannot be used in such processes. It is well known to use cationic polymers or copolymers such as polyaluminum chloride, polyamines and polydadmac as a coagulant and a polyacrylamide as a flocculant at different feed points in the wet-end of a paper machine. In spite of the several polymers presently being used in the paper mills to attain better runnability of the paper machines and/or to obtain a specific end use paper property, such as improved sheet formation for better printability or improved surface strength, there remains a very real and substantial need for a polymer composition for improving the paper or paperboard by improving the drainage, retention, and formation properties thereof during the paper making process. SUMMARY OF THE INVENTION The present invention has met the above-described need. The present invention provides a cationic polymer composition that can improve the retention of fillers, sizing and fiber fines in a paper making process, which speeds up drainage in the paper machine wire, and which improves sheet or paper formation which, in turn, enhances other physical and strength properties of the finished paper. The cationic polymer composition of the invention comprises a blend of two coagulants, preferably a polydadmac or a polyamine with a polyaluminum chloride silicate (PASS-C) . The ratio of polydadmac or polyamine to polyaluminum chloride silicate may range from 1:1 to 1:4 and 1:1 to 4:1. The polymer blend is not considered as being shear-sensitive and, therefore, can be added to the pulp stock or slurry at any point in the wet-end of the paper machine. This polymer composition may be used alone or in combination with a flocculant, preferably a polyacrylamide to enhance the dewatering or drainage efficiency. If a polyacrylamide is used, preferably, the cationic polymer composition of the invention is added first to the pulp stock or slurry in the wet-end of the paper machine, followed by addition of the polyacrylamide. Since polyacrylamide is shear-sensitive, preferably, it is added to the pulp or slurry after the shearing stages in order to preserve its efficiency. Other coagulants or polymers which may be used in conjunction with the polyaluminum chloride silicate (PASS-C) are polyethylene imines, polycyanogunidines, or copolymers containing DMDAAC (dimethyldiallylammonium chloride) . From the foregoing, it is appreciated that within the scope of the invention is a method of use of the cationic polymer composition and the polyacrylamide in a paper making process for paper and/or paperboard products. The paper and/or paperboard products are, for example, such products as newsprint, fine paper, and ' corrugated medium/board furnishes. DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a cationic polymer composition for particular use in the wet-end of a paper machine in the paper making process. In the paper making process, a paper product, that is paper or paperboard or the like, is made by the general steps of forming an aqueous cellulosic slurry, subjecting such slurry to at least one shear stage, and dewatering the slurry to form a paper product sheet, which process is characterized by unique steps concerning the sequence and point of addition of certain additives. The process includes the addition of a mineral filler such as calcium carbonate, kaolin clay, or the like and a cationic charge biasing species (coagulants) to the slurry prior to at least one shear stage, which additions and points of addition are also generally known for paper making processes. The dewatering of the slurry to form a paper product sheet generally comprises draining the slurry and then drying the sheet formed thereby. The addition of a cationic or an anionic flocculant is also known generally in the paper making process. A cationic species or coagulant is added to the slurry to at least partially neutralize the charge of the surfaces of the mineral filler and cellulosic fines and/or fibers larger than the fines. Most of all of the solids in nature have negative surface charges, including the surfaces of cellulosic fines and mineral fines. The cationic species in addition to partially neutralizing the surface charge on the fines and fillers, provide cationic patches or anchoring points on the mineral and fines for the anionic flocculant subsequently added to the slurry. The cationic polymer composition of the present invention has been found to work well as a cationic donor, i.e., providing cationic sites on the minerals and fines for the anionic flocculant and as a fixative for the colloidal fines as well as a drainage aid. Visual observations on the floes formed indicate the composition's use as a possible formation aid in addition to acting as a colloidal fixative, an anionic trash neutralizer, and a drainage aid. The cationic polymer composition of the invention comprises a blend of two coagulants where the first is a polynucleate aluminum silicate-sulphate compound containing a chloride referred to as PASS-C and the second coagulant is either a polyamine or a polydadmac (polydiallyldimethylammonium chloride) . The PASS-C product is available from Handy Chemicals Limited, (a subsidiary of Alcan Aluminum) and through Hydor-Tech, a licensed manufacturer of Handy Chemicals Limited. The cationic polymer composition of the invention can be used in acidic, neutral, or alkaline paper making processes . PASS-C contains a polyaluminum chloride silicate (PAC) component. It is believed by the inventors that this PAC component can be used as a sizing promoter to replace alum and that the presence of a cationic donor in the polydadmac or the polyamine should give better sizing efficiency than either of these chemicals when used alone as a coagulant in the paper making process. Other cationic polymers used in the composition of the invention may be polyethylene imines, polycyanogunidines, or copolymers containing DMDAAC (dimethyldiallylammonium chloride) . The ratio of the first coagulant to PASS-C may range from about 1:1 to 4:1. It is believed by the inventors that PASS-C may have been used as a polymer in effluent water treatment but has never been used for the retention, drainage, and/or formation of paper products. An effective amount of the composition of the present invention should be employed in the paper making process. It will be appreciated by those skilled in the art that the dosage of the composition added to the aqueous cellulosic furnish being treated is dependent on the degree of retention, drainage, and formation desired. At least about one pound of the cationic polymer composition of the invention per ton based on the dry weight of furnish should be added to the aqueous cellulosic furnish. As used herein, the term "furnish" refers to all paper and paperboard furnishes based on, for example, but not limited to, mechanical pulp, semi-bleached kraft pulp, unbleached kraft pulp, and/or unbleached sulfite pulp . As used herein, an "effective amount" refers to the amount of the cationic polymer composition of the present invention necessary to bring about the desired result, such as, for example, the amount needed to improve drainage, retention or formation in the manufacture of paper or paperboard. It will be appreciated by those skilled in the art that the cationic polymer composition of the invention may be employed in conjunction with other additives used during the manufacture of paper or paperboard such as, but not limited to, fillers, pigments, binders, and strength aids. The cationic polymer composition of the invention may be added to the paper furnish (pulp stock or slurry) at any convenient point prior to sheet formation. Preferably, the composition is added to thin diluted aqueous cellulosic paper furnish. Preferably, the cationic polymer composition is not shear-sensitive so that it can be added to the paper furnish at any point in the wet-end of the paper machine, including before any of the shear stages. If the cationic polymer composition of the invention is to be used in conjunction with an anionic or cationic flocculant, such as a polyacrylamide, since the flocculant is generally shear-sensitive, then preferably this flocculant is added after the shearing stages (i.e., screens) to preserve its efficiency with regard to drainage and fiber fines or filler retention. Also, if a flocculant is to be used with the cationic polymer composition of the present invention, then preferably the cationic polymer composition is added first to the paper furnish in the wet-end of the paper machine followed by the flocculant. General Laboratory Procedure For Screening And Testing The Examples 1. Pulp Stock Pulp samples, also known as "thick stock" were taken from various pulp lines in two commercial paper mills . Samples of tray water or "thin stock" were also collected and mixed with the thick stock in order to dilute the thick stock to attain the consistency needed in the headbox. The percent solids for each of the samples taken from the thick stock and the thin stock was determined based on the ratio of the weight of the oven- dry fibers to the total weight of the sample slurry. From the percent solids of the fiber in the thin and thick stock samples, the required weight of each sample slurry in order to obtain a target or "mix" consistency at the headbox is easily determined. 2. Polymer Separation Each cationic donor, i.e., PASS-C, polydadmacs, polyamines, was prepared at 1% solids with distilled water. The flocculants were first made down at 2% solids, and then to 0.1% solids with distilled water. The first step dilution to 2% solids "uncoils" the polymer thereby maximizing its efficiency. Further dilution to 0.2% or 0.1% is necessary not only to reduce polymer viscosity but also to attain a better mixing with the cellulose fibers. A 0.1% final solids was chosen for better precision since small samples were handled. 3. Stock And Polymer Mixing, Time, Sequence and Speed Of Stirrer This varied according to the type of furnish, i.e., with or without fillers, and is shown respectively in Tables 1 and 2. Basically, a final slurry of about 500 ml was prepared. 4. Sample Preparation For Transmittance And Cationic Demand Determination (PCD) The slurry of Step 3 was passed through a Calgon drainage tube (mesh No. 100) until about 150 ml of the filtrate was collected. This filtrate was used for transmittance and cationic demand tests . For the fine paper evaluation of Examples Bl.l and B1.2,the drainage time for 100 ml of the filtrate through the tube was recorded and presented in the results. 5. Transmittance (%) Test A Hach DR 100 instrument was used with distilled water as the reference. "Good" distilled water is essentially free of colloidal impurities." This instrument measures transmittance at 450 NM wavelength. Distilled water is placed in a vial and the transmittance reading is adjusted to 100. The distilled water is then replaced by the sample and a reading is taken. This reading was recorded and is the transmittance percentage. The clearer the filtrate which is an indication of "good" colloidal fixation, the higher the transmittance percentage . 6. Cationic Demand Test (meq/L) A Mutek Particle Charge Detector (PCD) was used. 10 ml of the filtrate from the Calgon drainage tube of Step 4 was titrated until end-point with a 0.001 N standard polydadmac titrant . The 0.001 N (one equivalent wt . of solute per liter of solution) polydadmac titrant is an industry standard. The reading was multiplied by 100 in order to convert the reading into meq/L. The meq/L value represents the cationic demand of the system, or how much cationic polymer is required to neutralize the colloidal anionic trash or impurities in the system. A lower meq/L value indicates a more efficient polymer in trash neutralization. It is a relative value. Table 1 Speed Of Stirrer, Chemical Addition Sequence, And Time - With Fillers) Stock/chemical Time (sec) Stirrer speed (rpm) Comments Thick stock 0 1100-1200 Add thick stock to a Ball jar Filler 5 1100-1200 Add filler 'Coagulant 10 1 100-1200 Add coagulant 15 1100-1200 Add thin stock 20 600-800 Reduce stirrer speed 2 Flocculant 25 600-800 Add flocculant, if required 30 Stop stirring and pour slurry Into a Calgon drainage tube 1 Coagulant is polyamine, polydadmac and/or PASS-C as shown in Examples 2 Flocculant is anionic or cationic as shown in Examples Table 2 (Speed Of Stirrer, Chemical Addition Sequence, And Time - Without Fillers) Stock/chemical Time (sec) Stirrer speed (rpm) Comments Thick stock 0 1100-1200 Add thick stock to a Ball jar 'Coagulant 10 1100-1200 Add coagulant Thin stock 15 1100-1200 Add thin stock 20 600-800 Reduce stirrer speed 2 Flocculant 25 600-800 Add flocculant, if required 30 Stop stirring and pour slurry Into a Calgon drainage tube 1 Coagulant is polyamine, polydadmac and/or PASS-C as shown in Examples 2 Flocculant is anionic or cationic as shown in Examples Examples The following examples demonstrate the invention in greater detail. These examples are not intended to limit the scope of the invention in any way. In the examples, the following products were used: Hydraid ® 2010 is a high molecular weight polydadmac. Hydraid ® 2060 is a high molecular weight polyamine. Hydraid ® 2020 is a low molecular weight polydadmac. Hydraid ® 2050 is a low molecular weight polyamine. Hydraid ® 954 is a high charge, high molecular weight cationic flocculant. Hydraid ® 7706 is a low charge, high molecular weight anionic flocculant. Hydraid ® 7736 is a high charge, high molecular weight anionic flocculant. Hydraid ® 8736 is a high charge, high molecular weight anionic flocculant. ECCat ™ 2900 is a polyaluminum chloride (PAC) . The difference between Hydraid ® 7736 and 8736 is its chemistry of manufacture. Hydraid ® is a registered trademark of Calgon Corporation, Pittsburgh, PA, U.S.A. These products are commercially available from Calgon Corporation ECCat ™ is a trademark of ECC International Inc., Roswell, GA. PASS-C is a polyaluminum chloride silicate available from Handy Chemicals Limited or Hydor-Tech, Annacis Island, New Westminster, British Columbia, Canada In the examples, if the coagulant is a blend of Hydraid ® 2020 and PASS-C with a 2:1 ratio, then there are two parts Hydraid ® 2020 and 1 part PASS-C. The ratio amounts are given on a volume basis. The dosages of the chemicals are given in kilograms per ton based on the oven dry weight of the pulp fibers . The cationic polymer composition of the invention was used in a newsprint (Examples A) , fine paper (Examples B) , corrugating medium/board furnishes (Example C) , and coated machine furnish (Example D) as exemplified in the several following examples. The laboratory test procedure for each of the following examples was performed according to the procedure described hereinabove . Example Al .1 (Without Filler) Preliminary Screening - This work was done primarily to compare the existing commercial polymers (Samples Nos . 2-6) with each other and with the cationic polymer composition of the invention (Sample No. 7) . Transmittance and cationic demand were used as the criteria. A high transmittance value indicates "good" colloidal fixation, and a low cationic demand value indicates "good" anionic trash neutralization, or the capability of the polymer to neutralize the anionic trash. Generally, high amounts of anionic trash or "detrimental substances" interfere with fiber-to-fiber bonding which is undesirable. Therefore, these detrimental substances need to be neutralized and fixed onto the fibers. The chemicals were added to the thick stock only in the manner described in Table 2. A newsprint furnish consisted of the following: 37% GWD (groundwood) , 25% CTMP (chemi-thermomechanical pulp) , 22% semi-bleached kraft, and 16% paper machine broke (some clay in broke) . The paper furnish was diluted with machine white water to a 1% stock consistency with a stock pH of 5.2. The dosages of the chemicals of Samples 2-7 were in kilogram (polymer) per ton of oven-dry fiber. These amounts are shown below. The ratio amount of Hydraid 2050 to PASS-C in Sample 7 was 1:4 on a volume basis . Cationic Dosage Transmittance Demand Sample No Treatment (kqtT) (%) (meq/U 1 Control or Blank (no chemical) 0 31 270 2 Hydraid 2010 2 35 210 3 Hydraid 2060 2 44 190 4 Hydraid 2020 2 34 175 5 Hydraid 2050 2 41 190 6 • PASS-C 2 36 215 7 Hydraid 2050 and PASS-C blend (1 4) 2 41 190 *PASS-C is polyaluminum chloride silicate These results indicate that PASS-C can be used as a blend with Hydraid ® 2050 (a polyamine) and the blend performs similarly to the coagulants being used commercially. The blend is particularly interesting due to the smaller floes formed which were observed visually. Smaller floes result in better sheet formation. Example Al .2 (Without Filler) The work done in this example involved a two- component system which is generally applied in paper mills where the cationic donor acts as the coagulant and is added to the thick stock, and the flocculant is added to the thin stock. Addition of the coagulant and flocculant followed the procedure of Table 2. The flocculant (Hydraid 954) was dosed at 0.5 kg/ton of over - dry fiber while the remaining chemicals (except the control sample) were dosed at 2.0 kg/ton of oven-dry fiber. The paper furnish was the same as that in Example Al . l . The ratios given i: basis . Cationic Transmittance Demand Sample No. Treatment (%) (meq/L) 8 Control or Blank (no chemical) 35 205 9 Hydraid® 2010/954 54 160 10 Hydraid® 2020/954 59 120 11 Hydraid® 2050/954 58 120 12 Hydraid® 2060/954 62 120 13 954 (only) 42 190 14 PASS-C/954 50 160 15 2010/2050 (1:1) + 954 53 140 16 2010/PASS-C(1 :4) + 954 55 150 17 2050/PASS-C(1 :4) + 954 44 160 The results indicate that the polydadmac (e.g., 2010) can be blended with PASS-C (Sample No. 16) to improve colloidal fixation (from the transmittance results) and anionic trash neutralization (from the cationic demand results) compared to polydadmac (Hydraid ® 2010, Sample 9) alone. Based on visual observations of the Calgon drainage tube, the floes containing PASS-C (Sample Nos . 14, 16, and 17) appeared to be smaller and better distributed in the pulp stock as compared to the samples not containing PASS-C. These results may suggest that a PASS-C blend containing a high molecular weight polyamine (e.g.2060) (Sample No. 12) may give better transmittance and cationic demand results when compared to the low molecular weight polyamine of Sample Nos. 11 and 17. These results may also indicate that a greater amount of the polyamine or polydadmac than the ratios shown in Sample Nos. 15-17 of the blend of the invention may be necessary. Example Al .3 (Without Filler) This experiment was done to determine which polymer is the best for PASS-C. The newsprint furnish was the same as that for Example Al .1 and the dosages were the same as that for Example A1.2, i.e., 2.0 kg/ton of oven- dry fiber. The results were: Cationic Transmittance Demand Sample No. Treatment (%) (meq/L) 18 Control or Blank 33 200 19 2010/PASS-C (1.1) + 954 50 160 20 2020/PASS-C (1.1) + 954 48 145 21 2050/PASS-C (V1) + 954 49 140 22 2060/PASS-C (1.1) + 954 53 140 The results indicate that the best blend appears to be 2060 and PASS-C (Sample No. 22) . Example Al .4 (Without Filler) This experiment was done to determine the best ratio between 2060 and PASS-C of Example Al .3 above. The newsprint furnish was the same as that for Example Al .1 and the dosages were the same as that for Example Al .2 , i.e. 2.0 kg/ton of coagulant in the ratios shown below and 0.5 kg/ton of flocculant (954). The results were: Cationic Transmittance Demand Sample No Treatment (%) (meq/L) 23 Control or Blank 33 200 24 2060/PASS-C (4 1 ) + 954 58 120 25 2060/PASS-C (3 1 ) + 954 57 125 26 2060/PASS-C (2 1) + 954 56 130 27 2060/PASS-C (1.1) + 954 53 140 28 2060 + 954 57 130 These results seem to indicate that the ratio of coagulants, i.e., 2060 to PASS-C, should at least be 2:1 (Sample No. 26) in order to obtain good transmittance and acceptable cationic demand values. Examples Al .1 through Examples Al .4 above were conducted where both 2060 and PASS-C were made down to 1% solution and then mixed together. Example Al .5 below was performed to determine the effect if the two polymers, i.e., 2060 and PASS-C were mixed on a net product basis and then made down to a 1% solution. Example Al .5 (Without Filler) This experiment was performed to determine the best manner in blending 2060 and PASS-C together to form the composition of the present invention. The results were: Cationic Transmittance Demand Sample No Treatment (%) (meq/L) 29 Control or Blank 34 185 30 2060 first with dilution water and then PASS-C 57 125 31 PASS-C first with dilution water and then 2060 55 125 32 2060 and PASS-C premixed and then dil water 55 125 These results seem to indicate that the manner for blending the composition of the invention is inconsequential with regard to the performance of the composition. In that Examples Al .1 through Al .5 involved a newsprint furnish without any fillers, the chemicals were added to the stock according to the procedure shown in Table 2 above. The following Example A2.1 involved a newsprint furnish containing fillers and, thus, the chemicals were added according to the procedure of Table 1. Example A2.1 (With Filler) This experiment used the same newsprint furnish of Example Al .1 but included a commercial calcined clay filler. The clay loading was 10% of the furnish. Clay was first added to the stock followed by the coagulant and then the flocculant according to the procedure of Table 1. The coagulant dosage or coagulant blend (dosage in ratios as shown) was 2 kg/ton, while the flocculant (954) dosage was 0.5 kg/ton of dry-oven fiber. The results were: Cationic Demand Transmittance Sample No Treatment (meq/L) (%) 33 Blank, no clay no polymer 190 31 34 Blank with clay, no polymer 200 20 35 With clay no coagulant, with 954 170 30 36 With clay, 2010 and 954 110 48 37 With clay, 2020 and 954 140 36 38 With clay, 2050 and 954 160 31 39 With clay, 2060 and 954 100 55 40 With clay, PASS-C and 954 145 32 41 With clay, 2060/PASS-C (1 1) + 954 130 41 42 With clay, 2060/PASS-C (2 1) + 954 120 44 43 With clay, 2060/PASS-C (3 1) + 954 110 55 44 With clay, 2060/2020 (1 1) + 954 110 50 The results may indicate that the polymer composition of the invention comprising 2060 polymer and PASS-C used m conjunction with the 954 flocculant (Samples 41-44) work best with the newsprint furnish containing clay. Samples 39 and 43 may indicate that some 2060 polymer can be replaced with PASS-C and still produce equivalent fixation results, i.e., same transmittance of 55, but slightly lower charge neutralization effects, i.e., cationic demand of 110 meq/L (Sample 43) vs. 100 meq/L (Sample 39) . Similar to the previous experiments, the pulp stock containing the PASS-C visually exhibited smaller and more uniform floes than that not containing PASS-C. These features are important for the formation properties of the paper web. Example Bl .1 (Without Filler; A fine paper furnish consisted of 48% bleached softwood, 32% bleached hardwood, 12% coated broke, and 8% machine broke. The thick stock had a consistency of 3.5% while the thin stock for dilution into the thick stock had a consistency of about 0.07%. The final consistency after mixing the thick and thin stocks together was 0.45% which was the headbox consistency of the paper machine from which both stocks were taken. The pH of the final stock was 7.6. The adding of the chemicals into the stock was according to the procedure of Table 2. In view of the nature of this fine paper furnish, a cationic donor (coagulant) with a low molecular weight and a cationic flocculant with a low to medium charge and a low to medium molecular weight would be required. In view of this, Hydraid 2020 (a polydadmac) and 954 (flocculant) were selected. The ratios are shown in parenthesis next to the coagulant blends and the amounts are given next to the chemicals. For Sample 53, the amount of coagulant blend dosage was 0.5 kg/ton with a 2:1 ratio and the amount of 945 flocculant was 0.3 kg/ton. The results were : Cationic Drain Time Transmittance Demand Sample No. Treatment (sec) (%) (meq/L) 45 Control or Blank (no chemical) 17 13 60 46 2020, 0.5 kg/T 14 29 30 47 PASS-C, 0.5 kg/T 13 15 40 48 2020/PASS-C (2:1), 0.5 kg/T 13.5 29 30 49 945, 0.5 kg/T 9 45 27 50 7706, 0.5 kg/T 22 34 35 51 2020/945 (0.5/0.3 kg/T) 9.6 49 15 52 PASS-C/945 (0.5/0.3 kg T) 9.3 42 16 53 2020/PASS-C (2:1) + 945 (0.5 ' ) 8.6 51 12 These results indicate that the composition of the invention comprising a 2:1 ratio of 2020 with PASS-C in conjunction with the 945 flocculant (Sample No. 53) had the best performance in terms of drainage, transmittance, and cationic demand. Example B1.2 (With Filler) The fine paper furnish of Example Bl.l was used with a precipitated calcium carbonate (PCC) filler. The PCC was scalenohedral and was added at a 15% loading. The sequence of addition was: PCC and coagulant to thick stock, and then dilution with the thin stock, and finally the flocculant (945) . The results were: Cationic Drain Time Transmittance Demand Sample No Treatment (sec) (%) (meq/L) 54 Control or Blank 20 6 7 25 55 2020, 0 5 kg/T 18 5 14 16 56 PASS-C, 0 5 kg/T 18 5 10 17 57 2020/PASS-C (2 1) , 0 5 kg/T 19 15 15 58 945 , 0 3 kg/T 14 8 33 20 59 2020/945 (0 5/0 3 kg/T) 11 5 46 10 60 PASS-C/945 (0 5, 0 3) 12 4 48 13 61 2020/PASS-C(2 1) + 945 (0 5, 0 3) 11 8 48 10 These results show that overall the composition of the invention comprising 2020 coagulant and PASS-C in conjunction with 945 flocculant (Sample 61) performed the best . Example C A brown stock which is used for corrugating medium/board production was used m this experiment. The sequence of pulp and chemical, and the stirring speed generally were that of Table 2. The ratios for the coagulant blends appear in parenthesis and the amounts for either the coagulants or the coagulant blends and the flocculant were as shown below. The results were: Cationic Drain Time Transmittance Demand Sample No Treatment (sec) (%) (meq/L) 62 Control or Blank 48 20 42 63 2010 0 6 kg/T 42 42 24 64 2020, 0 6 kg/T 42 51 22 65 2050, 0 6 kg/T 39 42 22 66 2060, 0 6 kg/T 42 50 20 67 PASS-C 0 6 kg T 44 24 34 68 PASS-C/2060 (1 2), 0 6 kg/T 43 40 23 69 954, 0 4 kg T 30 30 32 70 2010@0 6 kg/T + 954 @ 0 4 kg/T 24 60 24 71 2020@0 6 kg/T + 954 @ 0 4 kg/T 22 65 20 72 2050@0 6 kg/T + 954 @ 04 kg/T 20 57 19 73 2060@0 6 kg/T + 954 @ 0 4 kg/T 19 69 16 74 PASS-C@0 6 kg/T + 954 @ 0 4 kg/T 26 33 30 75 PASS-C/2060 (1 2) @ 0 6 kg/T + 954 @ 0 4 kg/T 21 58 21 76 PASS-C/2060 (1 3) @ 0 6 kg T + 954 @ 0 4 kg/T 20 64 18 77 2020/2060 (1 1) @ 0 6 kg/T + 954 @ 0 4kg/T 20 59 22 These results seem to indicate that the best treatment is Sample 73 with the 2060 polymer used in conjunction with the flocculant, followed by Sample 76 having the PASS-C/2060 blend (1:3 ratio) with the 954 flocculant. The coagulants in this example were added to the thick stock while the flocculant was added to the thin stock in order to simulate the addition of the flocculant after a shearing stage, i.e., screening. Example D A coated machine furnish was used. This furnish consisted of 15% softwood, 45% hardwood, 10% coated broke, and 30% free broke. The composition of the invention comprising PASS-C with either polydadmac (2010 - Sample 86) or polyamine (2060 - Sample 85) with a 4:1 volume ratio were used in polymer screening in conjunction with commercial polymers (Part 1) . The coagulants were screened using thick stock and the best coagulant was then used with an anionic flocculant as indicated in Part 2. The criteria for selecting the best coagulant was based on drainage time and anionic trash neutralization indicated by the negative PCD values, explained hereinabove . The dosages are on a dry weight basis. The results for Part 1 were: Part 1 Dosage PCD Drainage Sample No. Treatment (#/T) (meq/L) (sec/100 ml) 78 Blank 0 -261 20.9 79 2010 2.5 -67 21 80 2020 2.5 -44 12 81 2030 2.5 -82 19.4 82 2050 2.5 -56 Poor drainage 83 2060 2.5 - Poor drainage 84 PAC" 11.5 -219 10 85 PASS-C/2060 2.5 -119 24 86 PASS-C/2010 2.5 -146 8.5 ** PAC = polyaluminum chloride which is the coagulant presently being used by this commercial paper mill. The high charge/high weight coagulants (2010 and . 2060) produced relatively large floes which seemed to hinder drainage; however, when the 2010 coagulant was blended with PASS-C (Sample 86) , it produced the best drainage (8.5 sec/100 ml) and good charge neutralization (-146 PCD meq/L) when compared to the polyaluminum chloride (Sample 84) currently being used in the mill regardless of the higher dosage of the polyaluminum chloride, i.e., 11.5 lbs . /ton of PAC (Sample 84) vs. 2.5 lb. /ton of the blended PASS-C/2010 (Sample 86). It is believed by the inventors that an amount of 2.5 lbs . /ton of composition of the invention may be adequate for this mill application. Part 2 The PASS-C/2010 (Sample 86) blend was then used in combination with anionic flocculants and compared to the current retention aid program being used by the mill, which program includes the use of colloidal silica. The blend of the invention was added at 2.5 lbs. /ton on a dry weight basis to thin stock before the flocculant was added. The results were: PCD Transmittance Drainage Sample No. Treatment (meq/L) (%) (sec/100 m/L) 87 Control (PAC @ 11.5 #/T) -69.8 4 40 88 7706**(0.6#/T) -19.8 18 39.9 89 7736 * *(0.6 #IT) 43.7 10 40 90 8736* * (o.6 #/T) 37 11 40.6 91 Current program *** -28.8 11 40.1 ** Treatment for samples 88-90 included a coagulant (2010/PASS-C @ 1:4 ratio) at 2.5#/T. The 7706, 7736, and 8736 are anionic flocculants. Current program is 11.5 #/T of PAC, 0.6#/T of anionic flocculant and 2#/T of BMA (Colloidal Silica) . These results seem to indicate that with the proper anionic flocculant which is 7736 in this example, the PASS-C/2010 blend of the invention improves retention (highest transmittance value of 18) without sacrificing drainage. The drainage times for Sample Nos. 87-91 were basically the same. Example E Experimental This experiment was performed to show the synergy between PASS-C and Hydraid 2010. Thick stock from the stuff box and machine white water samples were grabbed. Meanwhile, 1% polymer solutions were prepared from the following: Hydraid 2010 (high molecular weight polydadmac) , PASS-C and ECCat 2900 (PAC) . The required dosages of the polymers were added to a certain volume of the thick stock and the consistency of the stock was diluted to 1% bringing the total volume of the slurry to 500 ml. The schedule of mixing was as follows: T Tiimmee,, B Brriitttt JJaarr sec . Speed, RPM Comments 0 1200 Thick stock in Ball jar 10 Add polymer 2200--2255 Add WW (white water) to bring volume to 500 ml (cons. = 1%) 35 Stop stirring. Pour slurry into a Calgon drainage tube and record the time for 100 ml to drain. On the filtrate, do PCD and transmittance. For transmittance, use 1 part by volume of filtrate and 9 parts of distilled water. PCD is ran on the filtrate without further dilution , The results were: Treatment PASS-C, Hydraid® 2010 ECCat 2900 Drain Time PCD, No. #/τ #/T a/τ Sec/100 ml Trans., % meq/L 1 0 0 0 20.1 21 -147 2 1 0 0 10 29 -115 3 2 0 0 9 31 -112 4 3 0 0 8.2 35 -108 5 0 1 0 9.2 28 -106 6 1 1 0 8.4 34 -100 7 2 1 0 7.6 48 -94 8 0 2 0 8.5 33 -91 9 1 2 0 8 40 -89 10 0 3 0 9.4 36 -77 11 2.5 0.5 0 7.5 50 -95 12 1.5 1.5 0 7.8 42 -93 13 0 0 1 11 25 -125 14 0 0 2 10.5 25 -118 15 0 0 3 10 28 -113 16 0 1 2 9.8 30 -98 17 0 1.5 1.5 9.3 31 -98 18 0 2 1 9 32 -96 19 0 0 0 20.9 20 -143 In order to show synergy, the blend of PASS-C and Hydraid 2010 must show better results than either PASS-C or Hydraid 2010 used alone at the same dosage. Example Drain Time, PASS-C Hydraid 2010 sec . Trans . , 2 0 9 31 0 2 8.5 33 1 1 8.4 34 The blend of PASS-C and Hydraid 2010 showed slightly better drainage and transmittance results indicating a possible synergy. The next step was to look at a higher dosage of pounds/ton. Drain Time, PASS-C Hyd: raid 2010 sec T rans . , o o 3 0 8.2 35 0 3 9.4* 36 2 1 7.6 48 1 2 8 40 2.5 0.5 7.5 50 1.5 1.5 7.8 42 Large floes were seen visually. Treatments involving blends of PASS-C and Hydraid 2010 showed faster drainage and higher transmittance. These seem to indicate synergy between PASS-C and Hydraid 2010. The next question was whether any synergy could be seen between ECCat 2900 (PAC) and Hydraid 2010 (high molecular weight polydadmac) . Drain Time, ECCat 2900 Hyd:raid 2010 sec . Trans . , "6 3 0 10.5 25 0 3 8.5 33 2 1 9.8 30 1 2 9 32 1.5 1.5 9.3 31 The above results seem to indicate that there is no synergy between ECCat 2900 (straight PAC) and Hydraid 2010. From the above data, it will be appreciated by those skilled in the art that the coagulant composition of the invention comprising PASS-C with a polyamine or a polydadmac and a method of use of composition in a paper making process for making paper or paperboard significantly improve the parameters of drainage, retention and formation over known cationic polymer technology generally employing a single cationic polymer. Other cationic polymers such as polyethylene imines, polycyanogunidines, and copolymers containing DMDAAC may also be used with the PASS-C. Whereas particular embodiments of the present invention have been described for purpose of illustration, it will be evident to those skilled in the art that numerous variations and details of the invention may be made without departing from the invention as defined in the appended claims.

Claims: WHAT IS CLAIMED IS: 1. In a paper furnish, an improved cationic polymer composition for improving properties in the area of retention, drainage, and formation properties, said composition comprising: a first coagulant being cationic polynucleate aluminum hydroxy silicate - sulphate compound containing a chloride molecule (PASS-C) ; and a second coagulant being selected from the group consisting of a polyamine, a polydadmac, a polyethylene imine, a polycyanogunidine, and a copolymer of DMDAAC. 2. The paper furnish of Claim 1 wherein the ratio of said second coagulant to said first coagulant ranges from about 1:1 to about 1:4 and from about 1:1 to about 4:1. 3. The paper furnish of Claim 1 wherein said second coagulant is a polydadmac. 4. The paper furnish of Claim 1 whereinsaid second coagulant is a polyamine. 5. The paper furnish of Claim 1, further comprising: a cationic flocculant which is added to said furnish after said cationic polymer composition. 6. The paper furnish of Claim 5 wherein said cationic flocculant is a cationic polyacrylamide. 7. The paper furnish of Claim 1, further comprising: an anionic flocculant which is added to said furnish after said polymer composition. 8. The paper furnish of Claim 2 wherein said anionic- flocculant is an anionic polyacrylamide. 9. The paper furnish of Claim 2 wherein said furnish is selected from the group consisting of newsprint furnish, fine paper furnish, and corrugating medium/board furnish. 10. The paper furnish of Claim 1 wherein said furnish contains fillers. 11. The paper furnish of Claim 9 wherein said furnish is a newsprint furnish. 12. The paper furnish of Claim 9 wherein said furnish is a fine paper furnish. 13. The paper furnish of Claim 9 wherein said furnish is a corrugating medium/board furnish. 14. A process in which paper or paperboard is made by forming an aqueous cellulosic paper furnish having improved properties in the areas of retention, drainage, and formation which comprises: (a) adding to said furnish an effective amount of a cationic polymer composition comprising a first coagulant being a polynucleate aluminum hydroxysilicate-sulphate with a chloride molecule (PASS-C) and a second coagulant being selected from the group consisting of a polyamine, a polydadmac, a polyethylene imine, a polycyanogunidine, and a copolymer containing DMDAAC; (b) draining the furnish to form a sheet; and (c) drying said sheet. 15. The process of Claim 14 providing ratios of said second coagulant to said first coagulant in blends ranging from about 1:1 to 1:4 and 1:1 to 4:1. 16. The process of Claim 14 wherein said second coagulant is a polyamine. 17. The process of Claim 14 wherein said second coagulant is a polydadmac. 18. A process of Claim 14 further comprising the step of adding a cationic flocculant to said paper furnish at least after said furnish passes through its last shearing stage . 19. A process of Claim 18 wherein said cationic flocculant is added to said furnish after adding said cationic polymer composition to said furnish. 20. A process of Claim 14 further comprising the step of adding an anionic flocculant to said furnish after adding said cationic polymer composition to said furnish. 21. A process of Claim 20 wherein said cationic flocculant is a polyacrylamide. 22. A process of Claim 20 wherein said anionic flocculant is a polyacrylamide. 23. Paper or paperboard produced by the process of Claim 14 wherein said paper or paperboard has improved properties in the area of retention, drainage, and formation.

Inventors: LASMARIAS VICENTE B, WALSH DENIS, LASMARIAS, VICENTE, B., WALSH, DENIS
Applicants: ECC INT INC, LASMARIAS VICENTE B, WALSH DENIS, ECC INTERNATIONAL INC., LASMARIAS, VICENTE, B., WALSH, DENIS
Application year: 1999
Main classification: D21H21
IPC codes: B01D21, D21H17, D21H21, D21H23