MXPA02003881A

MXPA02003881A - Cationically modified polysaccharides.

Info

Publication number: MXPA02003881A
Application number: MXPA02003881A
Authority: MX
Inventors: D Vrbanac Michael
Original assignee: Weyerhaeuser Co
Priority date: 1999-10-19
Filing date: 2000-09-07
Publication date: 2002-10-23
Also published as: SE0201183D0; WO2001029313A1; SE521309C2; SE0201183L; US20020139501A1; KR20020060204A; US20040031579A1; CN1377436A; AU7122100A; JP2003512541A; CA2386403A1

Abstract

A modified polysaccharide having enhanced surface charge. The polysaccharide is modified to include a cationic polymer, preferably a polyquaternary amine, and has a surface charge from about plus;5 to about plus;20 mV. The modified polysaccharide can be advantageous incorporated into a papermaking furnish with enhanced retention.

Description

POLARIZED MODIFIED POL1SACARIDS FIELD OF THE INVENTION The present invention relates to modified polysaccharide as a filler and reinforcement aid for paper and paperboard products and, more particularly, to polysaccharide having improved surface charge.

BACKGROUND OF THE INVENTION One goal in papermaking is to increase the amount of filler in the final product to reduce the amount of fiber, a relatively expensive compound. The increase in the amount of filler should not have an adverse effect on the formation of paper size and other necessary properties. Among the fillers, starch is attractive due to its low cost and availability. In general, raw unmodified starch is not well retained in papermaking pulps due to lack of effective interaction with fibers and retention aids. Despite this disadvantage, methods using starch as a filler in papermaking have been designed. In most paper and cardboard manufacturing, the starch is completely sewn and used in a size press. The size press starch may include additives imparting desirable properties to a paper or board such as improved ting, stiffness, bonding, dusting, surface adhesion, among others. The cationic starch is typically added at the wet end of the papermaking machine and can improve paper strength properties and fine particle retention. Other charged synthetic polymers can be combined with cationic starch to improve the total fine particle retention. Uncooked and unmodified raw starch particles are not added to the wet end of a paper machine due to their unacceptable low retention. Crude starch has a particle surface charge close to zero when it is formed in suspension in water. This lack of surface loading results in a weak interaction with charged retention aids and / or fibers. Without strong interaction (eg, chemical adhesion), the starch can not be retained well in a papermaking system. Mechanical filtration of starch particles can result in some retention of starch in a fibrous web, but such retention requires a specific type of headbox configuration. However, by adding a surface charge to the raw starch particles, it is possible to dramatically increase the retention of starch in a network. Such increased starch retention is achieved through the use of retention aids which form a bridging adhesion between the charged starch particles and the surfaces of the fibers. Adding filler to raw starch has previously been achieved by chemical modification of starch through the covalent adhesion of certain functional groups, for example, quaternary amine groups, to the starch. In papermaking, these chemically modified starches are typically fired completely and then added to the wet end of the paper forming machine. Such a chemical modification process adds considerable costs to the starch and, additionally, does not result in a starch having a surface charge sufficient to improve the retention of uncooked starch significantly beyond that of unmodified raw starch. Accordingly, there is a need for an economical filler for use in papermaking methods that provides for increased particle retention without adversely impacting size formation. There is also a need for fillers that have increased retention and, in addition, impart resistance to paper products in which they are incorporated. The present invention seeks to satisfy these needs and provides additional related advantages.

BRIEF DESCRIPTION OF THE INVENTION In one aspect, the present invention provides a modified polysaccharide having an improved surface charge. The polysaccharide of the invention is a polysaccharide that has been modified to include a cationic polymer. The modified starch formed in accordance with the present invention has a surface charge of +5 to about +20 mV. The modified polysaccharide can be advantageously incorporated into a papermaking pulp with improved retention. In another aspect of the invention, paper products are provided which include the modified polysaccharide having improved surface charge. Paper products including the modified polysaccharide have increased strength compared to similarly constituted paper products that do not include the modified polysaccharide. In one embodiment, the paper product includes cellulosic fibers and the modified polysaccharide. In another embodiment, in addition to cellulosic fibers and modified polysaccharide, the paper product further includes a retention aid that enhances retention of the modified polysaccharide to the fibers. The retention aid can be a retention aid loaded positively or negatively. In additional aspects, the invention provides methods for forming the modified polysaccharide having improved surface charge and methods for forming paper products having increased filler retention and increased resistance through incorporation of the modified polysaccharide.

BRIEF DESCRIPTION OF THE DRAWINGS The aforementioned aspects and many of the advantages that accompany this invention will be appreciated more easily as they are better understood by reference to the following detailed description, when taken in conjunction with the drawings appended, in which: Figure 1 is a schematic illustration of an illustrative modified polysaccharide formed in accordance with the present invention.

DETAILED DESCRIPTION OF THE PREFERRED MODALITY In one aspect, the present invention provides polysaccharide having improved surface charge. The polysaccharide has been modified to include a cationic additive that imparts a positive charge to the polysaccharide surface. As used herein, the terms "polysaccharide" and "starch" are interchangeable, and the terms "modified starch" and "modified polysaccharide" refer to a polysaccharide having improved surface charge formed in accordance with the present invention. Suitable cationic additives include materials that can be irreversibly and / or strongly associated with starch and, when associated with starch, improve their surface charge. Cationic additives include organic polyelectrolytes and polymers. Preferably, the cationic additive includes a cationic polymer such as a polyuatemary amine. In a preferred embodiment, the cationic additive is a relatively low molecular weight polyuatemary amine charged in a highly positive manner having a molecular weight on the scale of 1 to 5 million grams per mole and about 3 milequivalents of quaternary amine per gram. Such a polyuatemary amine is commercially available under the designation Nalco 7527 from Nalco Chemical Co., Naperville, IL. The cationic additive is present in the starch in an amount of about 0.453 to about 6.80 kilograms / ton of starch in a dry base and preferably, about 2.6 kilograms / ton of starch. Other cationic additives which are useful in forming modified starches of the invention include cationic polyacrylamides, aluminum sulfate, cytosan, polyamines, polyamidoamines, polyethylene imines, polyamide-epichlorohydrin (PAE), polyalkylene polyamine, epichlorohydrin (PAPAE), and amine polymer. epichlorohydrin (APE). The modified starch formed in accordance with the present invention has a surface charge in the range of about +1 mV to about +100 mV and preferably from about +5 to about +20 mV as determined by the zeta potential measurement. Starches from a variety of sources can be modified to provide starches having improved surface charge. Suitable starches are available from corn, potatoes, tapioca, peas and wheat, among other sources. The modified starch of the invention can be formed from a suspension of uncooked raw starch and cationic additive in water.

In one embodiment, uncooked raw starch is added to water of pH 10 to provide a suspension having approximately 7% solids. The starch swells in the alkaline solution which looks like a milky paste. Although the swelling occurs, the starch remains in the form of discrete particles. However, at a higher pH, the starch can be formed in gel as a result of denaturation (ie, chemical cooking). Gelatinization during modified starch formation should be avoided. Without being limited by the following theory, it is proposed that the cationic additive diffuses on the surface of the swollen starch particle to provide a charged surface particle. The cationic additive is then trapped within the starch particle by adjusting the pH of the treated starch suspension with cationic additive at approximately neutral pH. With the addition of the cationic additive, the starch changes in appearance from a milky paste to granular sand type particles. Alternatively, in another embodiment, the modified starch can be formed by adding the cationic additive to a suspension of starch at about pH 7. Although the amount of swelling at neutral pH is less than that which occurs at an alkaline pH, the swelling is sufficient to provide a modified starch that has improved surface charge. In a preferred embodiment, the modified polysaccharide is a granular polysaccharide. A schematic illustration of a representative starch particle formed in accordance with the present invention is illustrated in Figure 1. With reference to Figure 1, the modified starch particle 10 includes cationic additives 12 adhered to the starch particle 14. The preparation and properties of exemplary modified starches having improved surface charge are described in Example 1. Measurement of the surface charge of representative improved surface charge starch particles formed in accordance with the present invention is described in Example 2. The modified starch of the invention can be advantageously incorporated into a pulp of papermaking paper. As described below, the modified starch is highly retained by the pulp thereby rendering the modified starch an economical filler for paper products. In addition, paper products that incorporate the modified starch pulp have improved strength. The retention of the modified starch in the pulp is increased compared to uncooked raw starch. As described in Example 3, the Britt vessel experiments demonstrate that the modified starch can be retained by the pulp to an equal or greater degree compared to the precipitated calcium carbonate (PCC), a conventional filler. Generally, for a thin paper stock, about 60 to about 70 percent modified starch was retained under conditions that resulted in the retention of approximately 45 percent PCC.

The modified starch can be highly retained by the pulp to provide a pulp that can yield a paper product having a high filler retention. Alternatively, in addition to the modified starch, other retention aids may be added to the pulp to further increase the retention of the modified starch. The retention aids include those known in the papermaking art and the anionic and cationic retention aids described below. An anionic retention aid or additive can be used to increase the retention of modified starch. Anionic retention aids include polyelectrolytes and anionic organic polymers. Preferably, the anionic retention aid includes an anionic polymer such as, for example, anionic polyacrylamide (APAM). In a preferred embodiment, the anionic retention aid is a slightly negative charged, relatively high molecular weight polyacrylamide. The preferred polyacrylamide has a molecular weight in the range of about 8 to about 15 million grams / mole and is a copolymer of acrylic acid (30 mole percent) and acrylamide (70 mole percent). Said polyacrylamide is commercially available under the designation Accurac 171 from Cytec Industries Inc., West Patterson, NJ. Alternatively, the anionic polyacrylamide is commercially available under the designation Nugen 24 from Northwest Specialty Chemicals, Vancouver, WA. The anionic retention aid is present in the fibrous pulp in an amount of about 0.04 to about 1.35 kilograms / ton fiber, and preferably about 0.226 kilograms / ton fiber. Other suitable anionic retention aids include high molecular weight anionic flocculants. As described in Example 3, a representative anionic retention aid is preferably added to the pulp at the wet end of the papermaking machine and can be added to the pulp before the addition of the modified starch, simultaneously with the addition of the modified starch, or after the addition of the modified starch. As illustrated in Table 9, the largest retention (72 weight percent) was achieved with the addition of APAM to the pulp followed by the addition of the modified starch. The second largest retention (58 weight percent) was the addition of the modified starch to the pulp followed by the addition of APAM. Both of these conditions provided a higher filler retention than the typical alkaline fine paper system (45 percent by weight). Other additives can also advantageously increase the retention of the modified starch by the pulp. For example, cationic retention aids and additives can increase pulp retention of the modified starch. Preferably, the cationic retention aid includes a cationic polymer such as, for example, a cationic polyacrylamide (CPAM) which has a relatively high molecular weight and is charged in a slightly positive manner. The preferred polyacrylamide has a molecular weight in the range of about 8 to about 15 million grams / mole and is a copolymer of acrylamide (90 mole percent) and a quaternary amine monomer (10 mole percent). Said polyacrylamide is commercially available under the designation Accurac 182RS from Cytec Industries Inc., West Patterson, NJ. The cationic retention aid is present in the fibrous pulp in an amount of from about 0.04 to about 5.43 kilograms / ton of fiber and, preferably, from about 0.18 to about 2.71 kilograms / ton of fiber. Combinations of anionic and cationic retention aids can be used with the modified starch to increase pulp retention. Other suitable cationic retention aids include high molecular weight cationic flocculants such as for example, cationic polyacrylamides commercially available from Nalco Chemical Co., Naperville, IL under the designations Nalco 7530 and 7520. Pulps containing the highly retained modified starches can be formed into paper products characterized by having a highly advantageous filler retention and increased strength . Paper products that benefit from the advantageous incorporation of modified starch include fine paper, newsprint, bleached cardboard, linerboard, medium board, and old corrugated cardboard (OCC), among others.

Paper products containing modified starch and, optionally, one or more of the retention aids described above can be formed by adding the modified starch and, if desired, the retention aid, to a pulp of paper pulp at the wet end of a paper machine. Depending on the desired properties of the paper product, the modified starch may be added to the pulp pulp in an amount of from about 0.5 to about 20 weight percent, and preferably from about 3 to about 10 weight percent based in the total weight of the fibers. The flow characteristic of a pulp of pulp, including the ability of pulp to be de-wetted, is an important factor in high-speed papermaking methods and machines. An advantage of the invention is that the addition of modified starch to a pulp of paper pulp does not adversely affect the flow characteristics of the pulp despite the high retention of the modified starch pulp. Additionally, the pulp is not adversely affected by the addition of the modified starch when the pulp is treated with an anionic retention aid according to the invention. The addition at the wet end of the modified starch to a pulp pulp treated with an anionic retention aid does not result in the formation of a gum-like precipitate, which would negatively impact the quality of the pulp of pulp and limit its utility in the production of high speed paper. Similarly, the addition of a cationic retention aid to a pulp of pulp containing an anionic retention aid and / or modified starch does not adversely affect the pulp of pulp. The formation and properties of an illustrative paper product, OCC, which contains modified starch are described in Example 4. The strength properties of the illustrative OCC product are summarized in Table 11. The results show that the breaking strength of Mullen for an OCC product containing 3 percent in modified starch weight is increased by approximately 20 percent compared to an OCC product similarly constituted that lacks the modified starch. There were also increases in compression of short time STFI, tension, and stretch. The OCC product had an increase in short-time STFI compression of approximately 5%, an increase in tension of approximately 9% and an increase in stretch of approximately 16% compared to an OCC product similarly constituted that lacks the modified starch . Illustrative OCC products were also formed by varying (a) the amount of cationic additive used to prepare the modified starch, (b) the amount of modified starch that is added to the pulp of the pulp, and (c) the type and amount of retention aid that is added to the pulp. the pulp of pulp. The starch retention percentage results for several representative OCC products are summarized in Table 12. With reference to Table 12, the results show that the modified starch is highly retained by the pulp and that the retention of modified starch can be increased. through the use of retention aids. The anion retention aid provides a greater retention improvement than the cation retention aid.

EXAMPLES EXAMPLE 1 Preparation of Enhanced Surface Charge Starch Representative In this example, the preparation and physical properties of representative starches having improved surface charge are described. Representative starches including a cationic polymer, a polyquaternary amine (PQA) were prepared as described for Group 1. Representative starches comprising a polyquaternary amine and also including a retention aid (APAM) were prepared as described for Group 2. Group 1.- A cationic potato starch (Accosize 80, commercially available from Cytec Industries Inc., West Patterson, NJ) was cooked at 3.85% solids in a laboratory cooking oven (44 g, 86% solids) in 1000 mL of deionized water. A 0.1% solution of a representative cationic polymer (a polyquaternary amine, PQA charged in a highly positive, low molecular weight, commercially available under the designation Nalco 7527 from Nalco Chemical Co., Naperville, IL) was diluted to 0.1% active (1.43 g, diluted to 500 mL). In each of the vessels for analysis, 1, 2 and 3, 5.71g of unmodified tapioca starch (OD d.Og) was diluted to 50mL with pH buffer at pH 10 and allowed to settle for 30 minutes . In the beaker for analysis 2, 0.95% cooked cationic potato starch (1.25 g of 3.78% solution) was added and mixed well. In the beaker for analysis 3, 1.58 kilograms / ton of Nalco 7527 (12.5 g of 0.1% solution) were added and mixed well. All three vessels for analysis were equilibrated for 30 minutes before microscopic observation. All three vessels for analysis were then adjusted to pH 7 with 1 N sulfuric acid and observed using a microscope. Ten percent by weight (based on O.D. pulp) of the three starch samples (1 ml of starch at about 7% solids) were each added to 1.0 g O.D. of pulp (bleached hardwood kraft pulp HWBK, Aspen, disintegrated, commercially available from Weyerhaeuser Co.) to a consistency of 0.5% and mixed. The starch samples were observed microscopically. Group 2.- Cationic potato starch (Accosize 80) was cooked 4. 5% solids in a laboratory baking oven (69 g, at 86% solids in 1340 ml deionized water). A 0.1% solution of Nalco 7527 was diluted to 0.1% active (1.43 g diluted to 500 ml). A 0.1% solution of a representative retention aid (a polyacrylamide, APAM, lightly charged, high molecular weight, commercially available under the designation Accurac 171 from Cytec Industries Inc., West Patterson, NJ) was diluted to 0.01. % of assets (1.43 g diluted to 500 ml and diluted 10 times). In each of the test vessels 1, 2 and 3, 5.0 g of unmodified tapioca starch (4.4 g of O: D :) was diluted to 50 ml with pH buffer at pH 10 and allowed to equilibrate for 15 minutes. minutes In beaker 2, 1.3% cationic potato starch (Accosize 80) was added (1.25 g of 4.5% solution) and mixed well. In the analysis vessel 3, 2.58 kg / ton PAQ (Nalco 7527) were added (12.5 g of 0.1% solution) and mixed well. After the chemical additions, the solutions were equilibrated for 30 minutes. All three vessels for analysis were then adjusted to pH 7 with 1 N sulfuric acid and allowed to stand for 1 hour.

Pulp Treatment Bleached hardwood kraft pulp (HWBK) was disintegrated and diluted to 0.25% consistency with deionized water. To each of six glasses for analysis, 0.5 g of pulp was added at a consistency of 0.25%. Three of the pulp samples were pre-treated with APAM adding 0.22 kg / ton (1.25 g of 0.01% solution). The pula was mixed well and then starch solutions were added to the pulp samples. To the pulp samples that were not pre-treated, 0.22 kg / ton of APAM (1.25 g of 0.01% solution) were added and mixed. All six conditions were analyzed qualitatively using a microscope. The first experiment was designed to qualitatively compare unmodified tapioca starch with the addition of cooked cationic potato starch or a cationic polymer, polyquaternary amine (PAQ). A microscope was used to observe any physical changes or reactions with other particles of starch or fibers. The microscope observations are summarized in table 1.

TABLE 1 Qualitative microscopic observations After the addition of the PAQ and the reduction in pH, there was a noticeable difference in the behavior of the starch suspension. The starch granules appeared highly dispersed. There was also some interaction between the modified starch and the fibers before and after the pH adjustment. The addition of cooked starch and PQA caused the starch particles to have some interaction when added to the fiber. The effect of post or pre-treatment of fibers with an anionic polymer (APAM) on the reaction of the modified starch solutions was also determined. In one case, APAM was added to the fiber before the addition of the starch suspension, and in the second case, APAM was added after the addition of the starch to the fibers. The observations are summarized in table 2.

TABLE 2 Qualitative microscopic observations The APAM treatment had a negligible effect on the appearance of fibers treated with the cationic starch and modified PQA starch.

EXAMPLE 2 Measurement of Surface Loading of Representative Improved Surface Loading Starch Particles In this example, the measurement of the surface charge of representative starch particles having improved surface charge is described. Surface loading was determined by means of zeta potential measurement.

Groups 1 and 2: Control and modified starches: unmodified tapioca starch was used for each test. To each starch sample (5.0 g) was added 50 ml of buffer solution at pH 10 and the solution was allowed to stand for one hour. After standing for one hour, 2.26 kg / ton (based on active) of PQA (Nalco 7527) was added to the starch and mixed well to provide "the modified sample". In the control sample, no polymer was added. The samples were allowed to stand for an additional hour before adjusting to pH 7 with 1N sulfuric acid. Samples were allowed to stand for an additional hour before analysis.

Group 3: Modified pH variation starches: the modified sample was prepared by adding 5.0 g of unmodified tapioca starch in 50 ml pH buffer at pH 10 (as described above) and allowed to stand for one hour before adding 2.26 kg / ton of PQA (Nalco 7527). After one hour, the pH was adjusted to pH 7 with 1N sulfuric acid and allowed to stand for a final hour. A second sample was prepared by adding pH buffer at pH 10 to 5.0 g of tapioca starch as received and then allowed to stand. After the hour, 2.26 kg / ton of PQA (Nalco 7527) were added and allowed to stand for another two hours without further adjustment of pH. A third sample was prepared as described above except that the pH regulator at pH 7 was added to the starch without further adjustment of pH.

Measurement of zeta potential. The zeta potentials for all samples were measured using a Delsa 440 (Coulter Electronics, Inc., Hialeah, FL) run at a frequency scale of ± 500 Hz and with a current equal to half the value of the conductivity of the sample . The sample was run at two ceiling heights (16 and 84). Due to the addition of the PQA, the samples remained slightly well dispersed and were allowed to settle for one hour before the analysis. The results of the zeta potential of the samples of group 1 are shown in table 3. The load is an average at angles of 8.6, 17J, 25.6, and 34.2 ° in the cell heights of 16 and 84. The control (sample no modified) was run in triplicate and the modified sample was run in duplicate. The results demonstrate that the addition of the cationic polyacrylamide gave the modified sample significantly improved loading compared to the control.

TABLE 3 Results of starch zeta potential measurement The zeta potential results of the group 2 samples are shown in Table 4. Because the settlement in a zeta potential cell can change the stationary plane, an experiment was conducted to test samples of various consistencies to determine the effect on the load analysis. The consistencies were varied by varying the settling times of the starch suspensions before analysis. The same samples were prepared as with the first group, and included a control and a modified sample. The modified sample was also washed with deionized water to determine whether the charge was on the particle surface or only weakly associated with the surface.

TABLE 4 Results of starch zeta potential measurement The results show that the settling time does not affect the zeta potential measurement. The results further indicate that the charge is on the surface of the particle and not only weakly associated with the surface, and that the washing of the starch particles has a negligible effect on the measurement of zeta potential. To determine the effect of pH on the formation of modified starch and on the total particle load, three samples were compared (group 3 samples prepared as described above). The results are shown in table 5.

TABLE 5 Effect of pH adjustment on the load All the modified samples had a similar cationic charge. It does not appear that the pH adjustment has a significant effect on the surface charge modification procedure.

EXAMPLE 3 Retention of starch pulp representative of improved surface loading In this example, the retention by the representative starch pulp having improved surface charge is described. To determine if the modified starch can be retained under high shear conditions, a Britt vessel was used for retention studies.

Preparation of pulp Prince Albert hard wood was refined to 400 ml CSF with the Escher Wyss conical refiner (Bird Escher Wyss, Manfield, MA) using the following conditions: 3.0% consistency, 1.0 W-s / m specific edge load, 1250 rpm, cutting length 0.583 km / s, and 60 degree bar angle. Prince Albert softwood was also refined to 600 ml CSF with the Escher Wyss using the same conditions except that the specific edge load was 3.0 W-s / m. The specific energy of pure energy for hardwood was 48.6 kW-h / t and for softwood it was 1.75 kW-h / t. A combination of 60% hardwood pulp and 40% softwood pulp was prepared. The very short pulp fibers were removed using a 200 sieve mesh box. The final unrefined value of the pulp mixture without very short pulp fibers was 695 ml at a consistency of 2.2%.

Britt vessel conditions A Britt vessel having a 100 mesh conical mesh screen was used in the determination of retention. The pulp was added in a Britt vessel with vanes with the stopper closed and mixed with the starch at various speeds. After a time for sampling, the stopper was opened and the filtrate was collected on a tare aluminum tray (approximately 100 ml). The tray was weighed immediately on the same weight of four places that was used for the tare. The tray was placed in an oven at 105 ° C until the next day. The dried sample was placed in a desiccator before re-weighing the tray. The consistency of the non-retained suspension was calculated from equation 1.

Consistency of filtered material = residue of grams O.D. Filtering of total grams (1) The retained percentage of the pulp suspension was calculated using equation 2. consistency of material consistency Percentage retained = suspension of filtered pulp x 100 (2) consistency of pulp suspension To determine the correct degree of shear or mixing speed, an initial study was made with a typical alkaline finely ground paper pulp. The retention of starch formed in accordance with the present invention was compared to the retention of precipitated calcium carbonate.

Chemicals.- The pulp prepared as described above was diluted to 0.65% consistency with deionized water. Precipitated calcium carbonate (PCC) was obtained from Specialty Minerals, Inc., Bethlehem, PA and had 31.6% solids. A solution of highly charged, high molecular weight anionic polyacrylamide (APAM, Accurac 171) was prepared by diluting 1.43 g APAM to 500 ml with deionized water. The solution was mixed with a Braun hand mixer for 15 seconds to provide a 0.1% APAM solution and then diluted 10X by diluting 50 ml from 0.1% to 500 ml with deionized water to provide a 0.01% solution. A solution of cationic potato starch (Accosize 80) was prepared by mixing 69.9 g of starch (86% solids) with 1340 ml of deionized water at 4.5% solids.

Britt-Pulp container procedure (2.5 g, 385 g of 0.65% consistency) was added to a Britt container. Table 6 shows the chemical additions and the amounts made to the pulp samples with the mixing times following each addition.

TABLE 6 Chemical addition order and mixing times The above conditions were run at three different mixing speeds, 500, 100 and 1500 rpm, with the ultimate goal of obtaining realistic filler retention. The typical filler retention on a fine paper machine is a retention of between 50-55%. Table 7 provides the results of mixing speed.

TABLE 7 Retention of Britt container filler: variation of mixing speed With reference to Table 7, the 500 rpm data set provides effective retention while the higher mix speed conditions show inadequate retention.

Retention of Modified Starch Retention of the modified starch of the present invention was compared to a typical alkaline fine paper stock with PCC. The APAM and cationic starch solutions were prepared the same as described above. In addition, a PQA solution (Nalco 7527) was prepared by diluting 1.43 g of supply material to 500 mL with deionized water. The PQA solution was 0.1% active and mixed for 15 seconds with a Braun hand mixer. The PCC was as described above. The pulp was diluted to a consistency of 0.42% with deionized water. The modified starch was prepared by diluting 5.0 g (12.5% solids) of unmodified tapioca starch to 50 mL with pH buffer at pH 10. The starch was mixed well and allowed to stand for one hour. A volume of 12.5 mL of 0.1% PQA (Nalco 7527) was added and mixed well. The solution was allowed to stand for another hour. The pH was then adjusted to pH 7 with 1 N sulfuric acid (approximately 2.7 mL). The final consistency of the starch solution was 6.7%. The control starch was prepared by diluting 5.0 g (12.5% solids) of unmodified tapioca starch to 50 mL with pH buffer at pH 10. The starch was mixed well and allowed to stand for one hour. A volume of 12.5 mL of deionized water was added and mixed well. The solution was allowed to stand for another hour. The pH was then adjusted to pH 7 with 1 N sulfuric acid (approximately 2.7 mL). The final consistency of the starch solution was 6.7%.

Britt vessel procedure For each Britt vessel experiment, 2.5 g of pulp (595 g at 0.42% consistency) were added and mixed using 500 rpm. For the control starch and the modified starch, 6.5 g of 6.7% starch were added (17.4%). For the APAM, 6.25 mL of a 0.01% solution were added (0.22 kg / ton) and for the cationic potato starch, 0.5 g of 4.5% solids were added (7.70 kg / ton). For the PCC, 1.6 g of solution at 31.6% were added (20%). The conditions are summarized in table 8. Each condition was run in triplicate and the whole experiment was randomized (except for the alkaline fine paper pulp which was first completed in triplicate).

TABLE 8 Chemical conditions of Britt's container Filler retentions (modified starch or PCC) are summarized in Table 9.

TABLE 9 Britt container filler retention: Order of variation of addition.

The highest retention was achieved with the addition of APAM to the pulp followed by the addition of the modified starch. The second highest retention was the addition of the modified starch to the pulp followed by the addition of the APAM. Both of these conditions had a higher filler retention than the typical alkaline fine paper system.

Effect of pH treatment on retention of modified starch The pulp that has the highest starch retention was obtained using pulp fibers that have been pre-treated with APAM. To evaluate the effect of pH on the retention of modified starch by the pulp, the pulp was treated with the modified starch under 3 different pH conditions. The pulp, APAM and PQA solutions were prepared as described above. The original pulp mixture was diluted to 0.41% consistency with deionized water. To add 2.5 g of O.D. pulp, 605 g of the 0.41% solution were used for each condition. Three solutions of starch were prepared in the following manner. Modified starch pH 10-7.- Five grams (12.5% solids) of unmodified oca starch were diluted to 50 mL with a buffer solution at pH 10. The starch was mixed well and allowed to stand for one hour. A volume of 12.5 mL of 0.1% Nalco 7527 was added and mixed well. The solution was left to rest for another hour. The pH was then adjusted to pH 7 with 1 N sulfuric acid (approximately 2.7 mL). The solutions were balanced for one more hour. The final consistency of the starch solution was 6.7%. Modified starch pH 10-10.- Five grams (12.5% solids) of unmodified oca starch were diluted to 50 mL with pH 10 buffer solution. The starch was mixed well and allowed to stand for one hour. A volume of 12.5 mL of 0.1% Nalco 7527 was added and mixed well. The solution was allowed to stand for two hours. The final consistency of the starch solution was 6.7%. Modified starch pH 7-7.- Five grams (12.5% solids) of unmodified oca starch were diluted to 50 mL with buffer solution pH 7. The starch was mixed well and allowed to stand for one hour. 12.5 mL of 0.1% Nalco 7527 were added and mixed well. The solution was allowed to stand for two hours. The final consistency of the starch solution was 6.7%.

Britt vessel procedure.- APAM was added to the pulp in the Britt vessel followed by mixing for 30 seconds followed by the addition of the starch suspension. For each run, 0.22 kg / ton of APAM (6.25 ml 0.01% solution) and 20% starch (7.4 mL of a 6.74% solution) were added. The experiment was randomized and each condition was run in triplicate. The results of pH variation are summarized in Table 10.

TABLE 10 Retention of filler in Britt vessel: pH variation.

All the conditions tested show a high starch retention with the pH7 / pH7 method that provides a slightly larger retention than the pH10 / pH10 condition.

EXAMPLE 4 Formation and Properties of Representative Improved Surface Loading Starch Confided by OCC In this example, the formation and properties of old corrugated cardboard (OCC) containing modified starch are described. The properties of representative OCC products were determined and compared with OCC products that do not include modified starch. The OCC product was formed from a fibrous paper pulp containing 100 percent OCC. The modified starch was prepared as described above by adding 2.26 kg PQA (Nalco 7527) / tonne of starch. The pulp of pulp was treated with 0.22 kg APAM (Accurac 171) / ton of fiber followed by the addition of 3 weight percent of modified starch based on the total fiber weight, and then 2.26 kg CPAM (Accurac 182RS) / ton of fiber. After depositing the pulp of pulp containing the modified starch in a foraminous support, the deposited pulp was dehydrated, and then dried to provide the OCC product. The properties of the OCC product prepared as described above are summarized in table 11. In the table, sample 1 refers to an OCC product that was formed without the inclusion of modified starch and sample 2 refers to a product of OCC which includes 3 weight percent modified starch based on the total weight of the starch. In the table, SSC STFI and TEA refer to short space compression STFI and voltage energy absorption, respectively.

TABLE 11 Properties of OCC containing modified starch? n With reference to Table 11, the Mullen breaking strength for the OCC product of samples 1 and 2 represents an increase of approximately 20% compared to OCC similarly constituted that lacks modified starch. There were also increases in compression of short lapse STFl, tension, and stretch. The OCC product containing modified starch had an increase in short-time compression STFl of 5%, an increase in tension of 9% and an increase in stretch of 16% compared to an OCC product similarly constituted that lacks starch modified. The percentage by weight of starch retained in representative OCC products was compared to one another and compared to OCC products containing unmodified starch. The results are summarized in tables 12-15. Several representative OCC products were formed by varying the amount of cationic additive used to prepare the modified starch, the amount of modified starch added to the pulp pulp, and the type and amount of retention aid added to the pulp pulp of the pulp. paper. The starch retention percentage results for several representative OCC products are summarized in Table 12. In these products, the cationic additive used to form the modified starch was PQA (Nalco 7527), the anion retention aid was APAM (Accurac). 171), and the cationic retention aid was CPAM (Accurac 182). The following terms are used in table 12: Modified starch refers to modified starch with 2.26 kg PQA (Nalco 7527) / tonne of starch; Variable PQA refers to an OCC product prepared by pretreatment of the pulp of pulp with 0.22 kg of APAM (Accurac 171) / ton of fiber before treatment with modified starch prepared from starch and variable amounts of PQA (Nalco 7527): A, B, C, and D refers to OCC products containing modified starch prepared from 0.45, 0.90, 1.35, 2.26 and 31.7 kg of PQA (Nalco 7527) / tonne of starch; Variable APAM refers to an OCC product prepared by pre-treating the pulp of pulp with varying amounts of APAM (Accurac 171) followed by treatment with modified starch prepared from starch and 2.26 kg of PQA (Nalco 7527) / tonne of starch; E, F, and G refers to OCC products in which the pulp of pulp was pre-treated with 0.11, 0.22 and 0.33 kg of APAM (Accurac 171) / ton of fiber. APAM / PQA / APAM refers to an OCC product in which the pulp of pulp was pretreated with 0.11 kg of APA (Accura 171), and then treated with modified starch prepared from starch and 2.26 kg of PQA (Nalco 7527) / ton of starch and 0.11 kg of APAM (Accurac 171) / ton of fiber; APAM / PQA / CPAM refers to an OCC product in which the pulp of pulp was pre-treated with 0.11 kg of APAM (Accurac 171), then treated with modified starch prepared from starch and 2.26 kg of PQA (Nalco 7527) / tonne of starch followed by 0.90 kg of CPAM (Accurac 182) / ton of fiber; and variable CPAM refers to an OCC product prepared by treating the pulp of pulp with varying amounts of CPAM (Accurac 182) after treatment with modified starch prepared from starch and 2.26 kg of PQA (Nalco 7527) / tonne of starch: H, I, and J refers to OCC products in which the pulp of pulp was treated with 0.45, 0.90, and 1.35 kg of CPAM (Accurac 182) / ton of fiber.

TABLE 12 Comparison of OCC starch retention.

The results in Table 12 show that the modified starch is highly retained by the pulp and that the retention of modified starch can be increased through the use of retention aids. The anion retention aid provides a greater retention improvement than the cation retention aid. The percentage by weight of modified starch retained in representative OCC products was determined as a function of amount of cationic starch additive (PQA, Nalco 7527) / tonne of starch, with pretreatment with 0.22 kg of anionic retention aid (APAM, Accurac). 171) / ton of fiber. The results are summarized in table 13.

TABLE 13 Retention of OCC starch: variation of PQA The results show that significant retention was achieved using 0.45 to 3J7 kg PQA / tonne of starch, with approximately 2.26 kg PQA / tonne of starch providing almost optimal retention. The percentage by weight of modified starch (2.26 kg PQA / tonne of starch) retained in representative OCC products was determined as a pre-treatment function with varying amounts of anionic retention aid (APAM, Accurac 171). The results are summarized in table 14.

TABLE 14 Retention of OCC starch: variation of APAM The results show that optimal retention was achieved for pre-treatment with 0.22 kg of anion retention aid / tonne of fiber. The percentage by weight of modified starch (2.26 kg PQA / tonne of starch) retained in representative OCC products was determined as a treatment function with varying amounts of cationic retention aid (CPAM, Accurac 182). The results are summarized in table 15.

TABLE 15 Retention of OCC starch: variation of CPAM The results show that significant retention was achieved using 0.45 to 1.35 kg of CPAM / tonne of starch. Although the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes may be made thereto without departing from the spirit and scope of the invention.

Claims

NOVELTY OF THE INVENTION CLAIMS 1. - A composition comprising a polysaccharide particle and a cationic additive, in which the cationic additive adheres to the polysaccharide particle to provide a polysaccharide particle having a positive surface charge. 2. The composition according to claim 1, further characterized in that the cationic additive comprises a cationic polymer. 3. The composition according to claim 2, further characterized in that the cationic polymer comprises a polyquaternary amine. 4. The composition according to claim 3, further characterized in that the polyquaternary amine has a molecular weight in the scale of 1 million to 5 million grams per mole. 5. The composition according to claim 3, further characterized in that the polyquaternary amine has approximately 3 meq of quaternary amine per gram. 6. The composition according to claim 1, further characterized in that the cationic additive is present in the composition in an amount of about 0.45 to about 6. 79 kg per ton of polysaccharide. 7. The composition according to claim 1, further characterized in that the surface charge is on the scale of about +1 mV to about +100 mV. 8. The composition according to claim 1, further characterized ... because the polysaccharide is selected from the group consisting of corn, potato, tapioca, pea and wheat starches. 9. A pulp of pulp comprising a polysaccharide particle having a positive surface charge, in which the polysaccharide particle having a positive surface charge comprises a cationic additive adhered to the polysaccharide particle. 10. The paper pulp according to claim 9, further characterized in that the cationic additive comprises a cationic polymer. 11. The paper pulp according to claim 10, further characterized in that the cationic polymer comprises a polyquaternary amine. 12. The paper pulp according to claim 9, further characterized in that the polysaccharide particle has a surface charge on the scale of about +1 mV to about +100 mV. 13. The paper pulp according to claim 9, further comprising an anionic retention aid. 14. - The paper pulp according to claim 9, further comprising a cationic retention aid. 15. The paper pulp according to claim 13, further comprising a cationic retention aid. 16. The paper pulp according to claim 13, further characterized in that the anionic retention aid comprises an anionic polyacrylamide. 17. The paper pulp according to claim 16, further characterized in that the anionic polyacrylamide comprises a copolymer of acrylic acid and acrylamide. 18. The paper pulp according to claim 17, further characterized in that the copolymer comprises about 30 mole percent acrylic acid and about 70 mole percent acrylamide. 19. The paper pulp according to claim 17, further characterized in that the copolymer has a molecular weight in the range from about 8 to about 15 million grams per mole. 20. The paper pulp according to claim 13, further characterized in that the anionic retention aid is present in the pulp in an amount of about 0.04 to about 1.35 kilograms per tonne of fiber. 21. - The paper pulp according to claim 14, further characterized in that the cationic retention aid comprises a cationic polyacrylamide. 22. The paper pulp according to claim 21, further characterized in that the cationic polyacrylamide comprises an acrylamide copolymer and a quaternary amine monomer. 23. The paper pulp according to claim 22, further characterized in that the copolymer comprises approximately 90 mole percent acrylamide and aprolO mole percent quaternary amine monomer. 24. The paper pulp according to claim 22, further characterized in that the copolymer has a molecular weight in the range from about 8 to about 15 million grams per mole. 25. The paper pulp according to claim 14, further characterized in that the cationic retention aid is present in the pulp in an amount of about 0.045 to about 5.43 kilograms per tonne of fiber. 26. A paper product comprising a polysaccharide particle having a positive surface charge, in which the polysaccharide particle having a positive surface charge comprises a cationic additive adhered to the polysaccharide particle. 27. - The paper product in accordance with the claim 26, further characterized in that the cationic additive comprises a cationic polymer. 28.- The paper product in accordance with the claim 27, further characterized in that the cationic polymer comprises a polyquaternary amine. 29. The paper product according to claim 26, further characterized in that the polysaccharide particle has a surface charge on the scale of about +1 mV to about +100 mV. 30. The paper product according to claim 26, further comprising an anionic retention aid. 31. The paper product according to claim 26, further comprising a cationic retention aid. 32.- The paper product in accordance with the claim 30, which additionally comprises a cationic retention aid. 33.- The paper product in accordance with the claim 30, further characterized in that the anionic retention aid comprises an anionic polyacrylamide. 34.- The paper product in accordance with the claim 31, further characterized in that the cationic retention aid comprises a cationic polyacrylamide. 35. - The paper product according to claim 26, further characterized in that the paper product is selected from the group consisting of fine paper, newsprint, bleached paperboard, coating board, medium board, and corrugated old cardboard. 36.- A method for forming a paper product comprising: adding a polysaccharide particle having a positive surface charge to a first pulp of pulp to provide a second pulp of pulp, in which the particle of polysaccharide having a positive surface charge comprises a cationic additive adhered to the polysaccharide particle; depositing the second pulp of pulp on a foraminous support to provide a wet network; and dehumidify and dry the wet web to provide the paper product. 37. The method according to claim 36, further characterized in that the cationic additive comprises a cationic polymer. 38.- The method according to claim 37, further characterized in that the cationic polymer comprises a polyquaternary amine. 39. The method according to claim 36, further characterized in that the starch particle has a surface charge on the scale of about +1 mV to about +100 mV. 40. - The method according to claim 36, further comprising adding an anionic retention aid to the first pulp of paper pulp. 41. The method according to claim 36, further comprising adding a cationic retention aid to the first pulp of paper pulp. 42. The method according to claim 40, further comprising adding a cationic retention aid to the first pulp of pulp 10 43. The method according to claim 40, further characterized by the anionic retention aid. comprises an anionic polyacrylamide. 44. The method according to claim 41, further characterized in that the cationic retention aid comprises a cationic polyacrylamide. 45.- The method according to claim 36, - * further characterized in that the paper product is selected from the group consisting of fine paper, newsprint, bleached cardboard, linerboard, medium board, and old corrugated cardboard. 46. A method for increasing the strength of a paper product comprising: adding a polysaccharide particle having a positive surface charge to a first pulp of pulp to provide a second pulp of pulp, in the which the polysaccharide particle having the positive surface charge comprises a cationic additive adhered to the polysaccharide particle; depositing the second pulp of pulp in a foraminous support to provide a wet network; and de-humidifying and drying the wet web to provide the paper product having increased strength compared to a similarly constituted paper that lacks a polsaccharide particle having a positive surface charge. 47. The method according to claim 46, further characterized in that the cationic additive comprises a cationic polymer. 48. The method according to claim 47, further characterized in that the cationic polymer comprises a polyquaternary amine. 49. The method according to claim 47, further characterized in that the polysaccharide particle has a surface charge on the scale of about +1 mV to about +100 mV. 50.- The method according to claim 47, further comprising adding an anionic retention aid to the first pulp of paper pulp. 51. The method according to claim 47, further comprising adding a cationic retention aid to the first pulp of paper pulp. 52. - The method according to claim 50, further comprising adding a cationic retention aid to the first pulp pulp 53. The method according to claim 50, further characterized in that the anion retention aid comprises a polyacrylamide anionic i * 54.- The method according to claim 52, V further characterized in that the cationic retention aid comprises a cationic polyacrylamide. The method according to claim 46, further characterized in that the paper product is selected from the group consisting of fine paper, newsprint, bleached cardboard, lining cardboard, medium cardboard, and old corrugated cardboard.