SE521309C2 - Granular polysaccharide with increased surface charge - Google Patents

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 +5 to about +20 mV. The modified polysaccharide can be advantageous incorporated into a papermaking furnish with enhanced retention.

Description

l5 20 25 30 Lu U '| 521 309 2 ten. This lack of surface charge results in a weak interaction with charged retention aids and / or fibers.

Without strong interaction (eg chemical adhesion), starch cannot be satisfactorily retained in a papermaking system. Mechanical filtration of starch particles can result in some starch retention in a fibrous web, but such retention requires a specific type of headbox configuration.

However, by applying a surface charge to the raw starch particles, it is possible to dramatically increase the starch retention in a web. Such increased starch retention is accomplished through the use of retention agents that form a bridging adhesion between the charged starch particles and the fiber surfaces. Addition of charge to crude starch has previously been accomplished by chemical modification of starch via covalent attachment of certain functional groups, eg quaternary amine groups, to the starch. In papermaking, these chemically modified starches are usually completely boiled and then added to the wet end of the paper machine. Such a chemical modification process adds a significant cost to the starch and, moreover, does not result in any starch with sufficient surface charge to improve the retention of uncooked starch significantly more than that of crude unmodified starch.

Thus, there is a need for an economical filler for use in papermaking methods that provides increased particle retention without adversely affecting bonding. There is also a need for fillers which have increased retention and which also give strength to paper products in which they are incorporated. The present invention seeks to meet these needs and provides additional related advantages.

SUMMARY OF THE INVENTION In one aspect, the present invention provides a modified polysaccharide with increased surface charge. The polysaccharide according to the invention is a polysaccharide which U 15 has been modified to include a cationic polymer.

The modified starch formed in accordance with the present invention has a surface charge of from about +5 to about +20 mV. The modified polysaccharide can be advantageously incorporated into a papermaking kit with improved retention.

In another aspect of the invention, paper products are provided which include the modified polysaccharide with increased surface charge. Paper products that include the modified polysaccharide have increased strength compared to similarly formulated 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 the cellulosic fibers and the modified polysaccharide, the paper product also includes a retention aid that improves the retention of the modified polysaccharide to the fibers. The retention aid can be either a positively or negatively charged retention aid.

In further aspects, the invention provides methods for making the modified polysaccharide with increased surface charge and methods for making paper products with increased filler retention and increased strength due to the incorporation of the modified polysaccharide.

BRIEF DESCRIPTION OF THE DRAWINGS The above aspects and many of the attendant advantages of the present invention will be more readily understood by reference to the following detailed description taken in conjunction with the accompanying drawings.

Fig. 1 schematically shows a representative modified polysaccharide prepared according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In one aspect, the present invention provides a polysaccharide with increased surface charge. The polysaccharide has been modified to include a cationic additive (u 521 5Û9j; 3Af; y ^ H 4 which gives the polysaccharide surface a positive charge. The terms "polysaccharide" and "starch" as used herein are interchangeable, and the terms "modified starch" and "modified polysaccharide" refer to a polysaccharide with increased surface charge provided in accordance with the present invention.

Suitable cationic additives include materials which can be irreversibly and / or strongly combined with starch, and which, when combined with starch, increase its surface charge. Cationic additives include cationic organic polyelectrolytes and polymers. Preferably, the cationic additive includes a cationic polymer, such as a polyquaternary amine. In a preferred embodiment, the cationic additive is a highly positively charged polyquaternary amine with a relatively low molecular weight in the range of about 1 to 5 million grams per mole and about 3 milliequivalents of quaternary amine per gram. One such polyquaternary amine is commercially available under the designation Nalco Chemical Co., Naperville, IL. The cationic additive is present on the starch in an amount from about 454 g (1 lb) to about 6810 g (15 lb) per ton of starch on a dry basis, preferably about 2270 g (5 lb per ton of starch.

Other cationic additives useful in the preparation of the modified starches of the invention include cationic polyacrylamides, aluminum sulfate, chitosan, polyamines, polyamidoamines, polyethyleneimines, polyamide piclorohydrin (PAE), polyolefin polyamine epichlorohydrin (PAPLHR) and APAPLYPHEMR .

The modified starch prepared according to the present invention has a surface charge in the range from about +1 mV to about +100 mV, +20 mV, as determined by zeta potential measurement. preferably from about +5 to about Starches from a variety of sources can be modified to be starches with increased surface charge. Suitable starches are available from, among others, corn, potatoes, tapioca, 10 15 20 25 30 521 3o9¿¿¿i; ¿,. The modified starch according to the invention can be prepared on the basis of a slurry of uncooked starch and cationic addition in water. In one embodiment, crude uncooked starch is added to water having a pH of 10 to produce a slurry of about 7% solids. The starch swells in the alkaline solution, which looks like a milky paste. Although swelling occurs, the starch remains in the form of discrete particles. At a higher pH value, however, the starch can be gelled as a result of denaturation (ie chemical boiling). Gelatinization during modified starch formation should be avoided. Without adhering to the following theory, it has been suggested that the cationic additive diffuses into the surface of the swollen starch particle to produce a surface charged particle. The cationic additive is then entrapped in the starch particle by adjusting the pH of the cationic additive treated starch slurry to approximately a neutral value. Upon addition of the cationic additive, the appearance of the starch changes from a milky paste to granular sand-like particles. In another embodiment, alternatively, the modified starch may be formed by adding the cationic additive to a starch slurry at a pH of about 7. Although the degree of swelling at neutral pH is less than that occurring at an alkaline pH value, the swelling is sufficient to give a modified starch with increased surface charge. In a preferred embodiment, the modified polysaccharide is a granular polysaccharide.

A schematic illustration of a representative starch particle prepared in accordance with the present invention is shown in Fig. 1. Referring to Fig. 1, the modified starch includes the particle 10 cationic additives 12 bound to a starch particle 14.

Preparations of and the properties of the representative modified starches with increased surface charge are described in Example 1. The measurement of the surface charge of repre 10o 15 20 25 30 (JJ UI 521 3o9; ¿¿¿¿¿»H 6 representative surface-charged improved starch particles prepared in accordance with the present invention are described in Example 2.

The modified starch of the invention can be advantageously incorporated into a papermaking kit. As described above, the modified starch of the pulp is largely retained, which makes the modified starch an economical filler for paper products.

In addition, paper products with the modified starch pulp have incorporated improved strength.

The retention of the modified starch in pulp increases in comparison with raw uncooked starch. As described in Example 3, experiments shown in a Britt dewatering container ("Britt jar") are loaded with pulp to an equal or greater extent equal to (Pcc), For a fine paper batch was retained until the modified starch can be retained with precipitated calcium carbonate a conventional filler. ranging from about 60 to about 70% modified starch under conditions that resulted in a retention of about 45% PCC.

The modified starch can to a large extent be retained by pulp to produce a pulp which can give a paper product with high filler retention. In addition to the modified starch, other retention aids may alternatively be added to the pulp to further increase the modified starch retention. Retention aids include those known in the papermaking art and the anionic and cationic retention aids described below.

An anionic retention aid or anionic additive may be used to increase the retention of the modified starch. Anionic retention aids include anionic organic polyelectrolytes and polymers.

The anionic retention aid preferably includes an anionic polymer, such as anionic polyacrylamide (APAM).

In a preferred embodiment, the anionic retention aid is a weakly negatively charged polyacrylamide of relatively high molecular weight. The preferred polyacrylamide has a molecular weight in the range of from about 8 to about 15 million b) U '| .... _ p - n-w f _., _, _,, ,, -. . , ', g - * H' I s f., ». l ''. . ,. ; 'I' ~ »k! . '_ °' 7 grams / mol and is a copolymer of acrylic acid (30 mol%) and acrylamide (70 mol%). Such a 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 mass in an amount from about 45.4 g (0.1 lb) to about 1362 g (3.0 lb), preferably about 227 g (0.5 lb) per ton of fibers.

Other suitable retention aids include anionic per tonne of fiber, high molecular weight flocculant.

As described in Example 3, a representative anionic retention aid (e.g., APAM) is preferably added, but may be added to the pulp prior to addition to the pulp in the wet modified paper of the papermaking machine, simultaneously with the addition of the modified starch or after the addition As shown in Table 9. (72% by weight) followed by the addition of the modified starch. the greatest retention was achieved by adding APAM to the pulp, the modified starch. The second largest retention (58% by weight) was obtained by adding the modified starch to the pulp, followed by the addition of APAM.

Both of these conditions gave a higher filler retention (45% by weight).

Other additives can advantageously also increase the fairness of the modified starch in the typical alkaline fine paper system. Cationic retention aids and additives can, for example, increase the mass retention of the modified starch. Preferably, the cationic retention aid includes a cationic polymer, such as a (CPAM), molecular weight and is weakly positively charged. The preferred cationic polyacrylamide having a relatively high polyacrylamide has a molecular weight in the range of about 8 to 15 million g / mol and is a copolymer of acrylic (90 mol%) (10 mol%). Such a polyacrylamide is commercially available under 1 __'- | 1 LJ.J.J. âr! amide and a quaternary amine monomer l0 15 20 25 30 b) U '| 8 designated Accurac l82RS by Cytec Industries Inc., West Patterson, NJ. The cationic retention aid is present in the fibrous mass in an amount of from about 45.4 g (0.1 lb) to about 5448 g (12 lb), preferably from about 181.6 g (0.4 lb) (6 lb). of anionic and cationic retention aids can be used together with per ton of fiber, to about 2724 g per ton of fiber. the modified starch to increase mass retention.

Other suitable cationic retention aids include high molecular weight cationic flocculants, such as cationic polyacrylamides commercially available from Nalco Chemical Co., under the designations Nalco 7530 and 7520.

Masses containing the highly retained starches of Naperville, IL, can be formed into paper products which are characterized by advantageously high filler retention and increased strength. Paper products that take advantage of the incorporation of the modified starch include topcoat (fl oia newsprint, bleached board, (OCC) fine paper, tong, medium board and old corrugated cardboard ”) etc.

Paper products containing modified starch and optionally one or more of the retention aids described above may be prepared by adding the modified starch and, if desired, one or more of the retention aids, to a bulk batch in the wet end of a papermaking machine. desired properties, the modified starch can be added to the pulp batch in an amount of from about 0.5 to 20% by weight, preferably from about 3 to about 10% by weight, based on the total weight of fibers.

The flow properties of a pulp batch, including the batch's ability to dewater, are an important factor in high speed methods of papermaking and machines _1_A_ 1 __ "1 '| _. L to be added thereto. An advantage of the invention is that the modified starch to a pulp batch does not adversely affect the flow properties of the batch, despite the high retention of modified starch of the batch. In batch 521 309 9 the batch is also 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 defined starch in the wet end of the pulp batch treated with an anionic retention aid does not result in the formation of a rubber-like precipitate, which would adversely affect the quality of the pulp batch and limit its usefulness in high speed papermaking. a mass batch contains they an anionic retention aid and / or modified starch do not pulp in any harmful way.

The preparation and properties of a representative OCC are described in Example 4. The strength properties of the representative paper product, containing modified starch, representative OCC product are summarized in Table II. The results show that the explosive strength according to Mullen for an OCC product containing 3% by weight of modified starch increases by about 20% compared with a similarly formulated OCC product that lacks modified starch. Increases of STFI compression over a short distance, traction and elongation were also observed. The OCC product had an increase in STFI compression over a short distance of about 5%, an increase in elongation of about 9% and an increase in elongation of about 16% compared to a similarly composed OCC product without modified starch.

Representative 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 added to the pulp, and (c) the type and amount of retention aid added to the pulp. . The results for the percentage of starch retention for various representative OCC products are summarized in Table 12. With reference to Table 12, the results show that modified starch is largely retained by pulp and that the retention of modified starch 10 15 20 U 30 (fl 521 309 10 can be increased by the use of retention aid) The anionic retention aid gave an increase in the retention which is higher than that given by the cationic retention aid.

EXAMPLES Example 1 Preparation of representative starch with increased surface charge E35.

This example describes the preparation of and the physical properties of representative starches with increased surface charge. The representative starches including a cationic polymer, namely a polyquaternary (PQA), Representative starches including a polyquaternary (APAM) amine were prepared as described for Batch 1. amine and in addition a retention aid was prepared as described for Batch 2.

Batch 1. A cationic potato starch (Accosize 80, commercially available from Cytec Industries Inc., West Patterson, NJ) was boiled at a solids content of 3.85% in a (449, Water. A 0.1% solution of a representative cationic laboratory cooker 86% solids) in 1000 ml of deionized polymer (a highly positively charged polyquaternary amine, PQA, low molecular weight, commercially available under the designation Nalco 7527 from Nalco Chemical Co., Naperville, IL) was diluted to 0.1 % active ingredients (1.43 g exposed to 500 ml).

In each of beakers 1, 2 and 3, 5.71 g of unmodified tapioca starch (5.0 g of oven dry) was diluted to 50 ml with a buffer solution having a pH of 10 and allowed to stand for 30 minutes. To beaker 2 was added 0.95% boiled cationic potato starch (1.25 g of 3.78% solution) and mixed well. To beaker 3 was added 2270 g (5 lb / ton Nalco 7527) (1.2 g of 0.1% solution) and mixed well.

All three beakers were equilibrated for 30 minutes before microscopic observation.

All three beakers were then adjusted to a pH of 7 with 1 N sulfuric acid and observed using a microscope using 10%. (oven dry on mass- lO 15 20 25 30 p.) U! 521 309 ll basis) of the three starch samples (1 ml of starch at one each was added to 1.0 g of oven- HWBK, Aspen, solids content of about 7%) dry pulp (bleached hardwood pulp, disintegrated, commercially available from Weyerhaeuser Co. ) at a concentration of 0.5% and mixed. The starch samples were observed microscopically.

Batch 2. Cationic potato starch (Accosize 80) was boiled at a solids content of 4.5% in a laboratory boiler (69 g, at a solids content of 4.5% in 1340 ml of deionized water). A 0.1% solution of Nalco 7527 was diluted to 0.1% active ingredients (1.43 g diluted to 500 ml). A 0.1% solution of a representative retention aid (a weakly negatively charged polyacrylamide, APAM, high molecular weight, commercially available under the designation Accurac 171 from Cytec Industries Inc., West Patterson, NJ) was diluted to 0.01 % active ingredients (1.43 g diluted to 500 ml and diluted 10 times). 2 and 3, 5.0 g of omo was diluted to 50 ml with I each of beaker 1 (4.4 g o.D.) a buffer solution having a pH of 10 and allowed to equilibrate tapioca starch for 15 minutes. To beaker 2 were added 1.3% cationic (1.3 g 4.5% solvent) (5.7 lb) (12.5 g of 0.1% solution) and potato starch (Accosize 80) and mixed well. To beaker 3 was added 2588 g per ton of PQA (Nalco 7527) mixed well. After the chemical additions, the solutions were equilibrated for 30 minutes. All three beakers were then adjusted for pH to 7 with 1 N sulfuric acid and allowed to stand for 1 hour.

Mass treatment. Bleached hardwood pulp (HWBK) was disintegrated and diluted to a concentration of 0.25% with deionized water. To each of six beakers was added 0.5 g of pulp at a concentration of 0.25%. Three of the pulp samples were pretreated with APAM by adding 227 g (0.5 lb) mixed well, per ton (1.25 g of 0.01% solution). Mass S after which the starch solutions were added to the b-mass samples. To the untreated pulp samples was then added 227 g (0.5 lb) per ton of APAM (1.25 g of 0.01% solution) and mixed. All six conditions were qualitatively analyzed using a microscope.

The first experiment was designed to qualitatively compare unmodified tapioca starch with the result of the addition of boiled cationic potato starch or a cationic polymer, namely polyquaternary amine (PQA). A microscope was used to observe any physical changes or reactions with other starch particles or fibers. The microscopic observations are summarized in Table 1.

TABLE 1 Qualitative microscopic observations Beaker After chemical addition After pH adjustment Reaction with fibers l (Control) No flocculation No flocculation No interaction 2 (cationic Some flock- Some flock- Some inter-starch) action 3 (PQA) No flock- No flock- Some internment (strong action dispersed) After the addition of PQA and reduction of the pH value, there was a remarkable difference in the properties of the starch slurry. The starch granules appeared strongly dispersed. There was also some interaction between the modified starch and the fibers before and after the pH adjustment. The addition of both cooked starch and PQA meant that the starch particles had some interaction when added to fibers.

The effect of post-treatment or pretreatment 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 fibers before the addition of the starch slurry, and in the other case, APAM was added after the addition of the starch to the fibers. These observations are summarized in Table 2.

TABLE 2 Qualitative microscopic observations Fibers post-treated with APAM Fibers pre-treated with APAM Beaker 1 (control) No fiber- Starch particles interaction uniformly located on fibers 2 (cationic Some starch- Some starch- starch) agglomeration / fiber agglomeration / agglomeration 3 (PQA) No fiber interaction No fiber interaction action Treatment with APAM had an insignificant effect on the appearance of fibers treated with either cationic starch or PQA-modified starch.

EXAMPLE 2 Measurement of the surface charge for representative starch particles with increased surface charge This example describes the measurement of the surface charge of representative starch particles with increased surface charge. The charged area was determined by zeta potential measurement.

Batches 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 a buffer solution of pH 10, and the solution was allowed to stand for 1 hour. After standing for 1 hour, 2270 g (5 lb) was added per ton (on a base basis). of active ingredients) PQA (Nalco 7527) to the starch and mixed well to obtain the "modified sample". No polymer was added to the control sample. The samples were allowed to stand for an additional 1 h before -v-Av LKJV * adjustment to a pH of 7 with 1 N sulfuric acid. were allowed to stand for an additional 1 hour before analysis. Batch 3: Modified starches via pH variation The modified sample was prepared by adding 5.0 g of unmodified tapioca starch to 50 ml of buffer (as described above) and allowed to stand under 1 hour before the addition of 2270 g (5 lb) of PQA (Nalco 7527) After 1 hour, the pH was adjusted to 7 with 1 N sulfuric acid and allowed to stand for another with a pH of 10 per ton for the final hour. sample was prepared by adding buffer with a pH of 10 to 5.0 g of tapioca starch in its existing state and then allowed to stand, after (5 lb) (Nalco 7527), and the solution was allowed to stand for another 2 hours without this hour. 2270 g per ton of PQA was added to any additional pH adjustment, and a third sample was prepared as described above, except that a buffer having a pH of 7 was added to the starch without any further pH adjustment.

Zeta potential measurement. The zeta potentials of all (Coulter samples were measured using a Delsa 440 Hialeah, FL), range of 500 Hz and with a current equal to Electronics, Inc., run within a frequency of half the sample conductivity value. The sample was run at two cell levels (16 and 84). Due to the addition of PQA, the samples remained fairly well dispersed and allowed to settle for 1 hour before analysis.

The zeta potential results from the Batch 1 samples are shown in Table 3. The charge is averaged at the angles of 8.6, 17.1, 25.6 and 34.2 ° at both cell levels of 16 and 84 times, and the modified sample was run twice.

The control (unmodified sample) was run three The results show that the addition of the cationic polyacrylamide gave the modified sample a significantly increased charge compared to the control. 10 15 20 521 509 15 TABLE 3 Results of zeta potential measurements on starch Sample PQA g / ton. PH Conductivity Mean value (lb / ton) (ms / cm) (mV) Control O 7 6.1 1.59 Control 0 7 9.5 2.67 Control 0 7 9.8 -2.95 Modified 2270 (5) 7 7.7 17.35 Modified 2270 (5) 7 9.1 18.22 The zeta potential results for the samples from Theorem 2 are shown in Table 4. tial cell can change the stationary plane, Since sedimentation in a zeta potency was performed an experiment with testing of samples with different concentrations to determine the effect on the charge analysis. The concentrations were varied by varying the sedimentation times for the starch slurries before analysis. The same samples were prepared as in the first batch and included a control and a modified sample. The modified sample was also washed with deionized water to determine if the charge was on the particle surface or was only slightly bound to the surface.

TABLE 4 Results from zeta potential measurements on starch Starch PQA g / ton pH Condition Conduct- Sediment- Medium (lb / ton) d activity activity time (mV) (min) Control 0 7 Unwashed 6.96 0 -2.08 Control O 7 Unwashed 9.75 9 -2.19 Control O 7 Unwashed 9.82 15 -2.47 Modified 2270 (5) 7 Unwashed 6.86 O 10.72 Modified 2270 (5) 7 Unwashed 7.95 9 15, 24 Modified 2270 (5) 7 Washed 8.40 9 10.10 The results show that the sedimentation time does not affect the zeta potential measurement. The results also show that the charge is present on the particle surface and is not only slightly bound to the surface, and that the washing of the starch particles has an insignificant effect on the zeta potential measurement.

To determine the effect of the pH on the production of modified starch and on the total particle charge, three samples were compared (samples from Batch 3 were prepared as the results are shown in Table 5).

TABLE 5 Effect of pH adjustment on charge described above).

Starch 7527 kg / ton Initial Final Conductivity Sediment Average (lb / ton) pH value pH value whitening time value (ms / cm) (min) (mV) Modified 2270 (5) 7 7 6.79 60 17 Modified 2270 (5) 10 10 8.00 60 15.86 Modified 2270 (5) 10 7 8.05 60 18.29 All of the modified samples had a similar cationic charge. It appears that the pH adjustment did not have a significant effect on the surface charge during the modification process.

EXAMPLE 3 Pulp Retention for Representative Starch with Increased Surface Charge This example describes the retention of representative starch with increased surface charge of pulp. To determine whether the modified starch can be retained at high shear conditions, a Britt dewatering container was used for retention studies.

Mass preparation. Prince Albert type hardwood was refined to 400 ml CSF with an Escher Wyss conical refiner (Bird Escher Wyss, Manfield, MA) using the following conditions: a concentration of 3.0%, a specific edge load of 1.0 Plumbing / m, 1250 rpm, a cutting length of 0.583 km / s and a Prince Albert rod angle were also refined to 600 ml CSF with eo °. Lövcrä ny; by means of the Escher Wyss device using 10 l5 20 25 30 La.) U1 521 309 l7 the same conditions, except that the specific edge load was 3.0 Vws / m. The net effect of the specific energy for hardwood was 48.6 kW + Mt and for softwood 1.75 kwl fl t. A pulp mixture of 60% hardwood and 40% softwood was prepared. The fines were removed using a 200 mesh screen. The final freeness value for the pulp mixture without fines was 695 ml at a concentration of 2.2%.

Conditions when using a Britt drainage tank A Britt drainage tank with a conical sieve of 100 mesh was used in the retention determination. The pulp was added to a blade-equipped Britt drainage container with the plug closed and mixed with the starch at different speeds. After time for sampling, the plug was opened and the filtrate was collected in a tared aluminum container (approx. 100 ml). The container was immediately weighed on the same four-place balance scale used for tare. The container was placed in an oven at 105 ° C until the following day. The dried sample was placed in a desiccator before weighing the container.

The concentration of the non-retained slurry was calculated from Equation 1.

Filtrate concentration = Grams of kiln dry residue (1) Grams of filtrate total The percentage of slurry suspended from the mass was calculated using Equation 2.

Percentage retained = Pulp slurry concentration - filtrate concentrate x100 (2) Pulp slurry concentration To determine the correct degree of shear or mixing speed, an initial study was performed with a typical batch of alkaline fine paper. The retention of the starch prepared in accordance with the present invention was compared with the retention of precipitated calcium carbonate.

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

Procedure with Britt drainage tank. Pulp (2.5 g, 385 g with 0.65% concentration) was added to the Britt container. Table 6 shows the chemical additives and the amounts added to the pulp samples with the mixing times after each addition.

TABLE 6 Order of chemical addition and mixing times Chemical Mixing time (s) 7718 g / ton (17 lb / ton) 15 cationic starch (0.47 g of 4.5%) 15% PCC (1.58 g of 3l, 6% ) 227 g / ton (0.5 lb / ton) APAM (6.25 g of 0.01%) The above conditions were used at three different ie 500, 100 and 1500 r / min, the ultimate aim to achieve realistic filler regeneration mixing rates, with tion. A typical filler machine or fine paper machine is between 50 and 55%. Table 7 shows the mixing speed results. 10 15 20 25 30 521 309 19 TABLE 7 Filler retention in Britt dewatering tank: Variation of mixing speed Mixing speed (r / min)% filler retention 500 50.4 1000 8.95 1500 4.5 Referring to Table 7, the value shown at 500 r / min effective retention, while conditions with higher mixing speed show insufficient retention.

Retention of modified starch The retention of the modified starch of the present invention was compared with a batch of a typical alkaline fine paper by PCC. The solutions with APAM and cationic starch were prepared as described above.

In addition, a PQA solution (Nalco 7527) was prepared by diluting 1.43 g of stock solution to 500 ml of deionized water. The PQA solution contained 0.1% of active ingredients and was mixed for 15 seconds using a Braun hand mixer. PCC was as described above. The mass was diluted to 0.42% concentration with deionized water.

The modified starch was prepared by diluting 5.0 g (12.5% solids) of unmodified tapioca starch to 50 ml with a buffer solution having a pH of 10. The starch was mixed well and allowed to stand for 1 hour. 12.5 ml of 0.1% PQA (Nalco 7527) was added and mixed well. The solution was allowed to stand for a further 1 hour. The pH was then adjusted to 7 with 1 N sulfuric acid (about 2.7 ml). the solution was 6.7%.

The final concentration of starch- The control starch was prepared by diluting 5.0 g of unmodified tapioca starch to 50 ml with a buffer solution having a pH of 10. (12.5% solids) The starch was mixed well and allowed to stand for 1 hour. volume of 12.5 ml of deionized water was added and mixed well.

The solution was allowed to stand for a further 1 hour. The pH was then adjusted to 7 with 1 N sulfuric acid (about 2.7 ml).

The final concentration of the starch solution was 6.7%.

Procedure when using Britt drainage containers. For each experiment with a Britt dewatering vessel, 2.5 g of pulp (595 g at 0.42% concentration) was added and mixed at 500 rpm.

For the control starch and the modified starch, 6.5 g of 6.7% starch (17.4%) were added.

For APAM, 6.25 ml of a 0.01% solution (227 g (0.5 lb) per tonne) was added, and for the cationic potato starch 0.5 g of 4.5% solids (7718 g (17 lb)) ) / ton)). (20%).

For PCC, 1.6 g of 31.6% solution was added. The conditions are summarized in Table 8. Each condition was used in three trials, and the whole trial was randomized (except for the batch of alkaline fine paper, which was first completed three times).

TABLE 8 Chemical conditions in Britt drainage tank First addition- Mixing time Second addition- Mixing time (s) ning (s) 17.4% modified 30 No 30 starch 17.4% modified 30 227 9 (0.5 lb) per 30 starch ton APAM 227 g (0.5 lb) 30 17.4% modified 30 per ton APAM starch 17.4% 30 No 30 control starch 17.4% control 30 227 g (0.5 lb) per 30 starch ton APAM 227 g (0.5 lb) 30 17.4% control- 30 per ton APAM starch 7718 g (17 lb) 227 g (0.5 lb) per per ton cationic 30 ton APAM 30 starch / 20% PCC Filler (modified starch or PCC) retentions are summarized in Table 9. 10 15 20 25 521 509 21 TABLE 9 Filler retention in Britt drainage tank: Variation of addition order Sample (first / second filler retention) the control / APAM 5 Modified / APAM 58 Cationic starch / PCC / APAM 45 APAM / Control 3 APAM / modified 72 Control / inge 1 Modified / none 10 The greatest retention was obtained by adding APA M to the pulp, followed by the addition of the modified starch. The second highest retention was obtained when adding the modified starch to the pulp, followed by APAM addition. Under both these conditions, a greater filler retention was obtained than in the usual alkaline fine paper system.

Effect of pH treatment on retention of modified starch Pulp with the highest starch retention was obtained by using pulp fibers pretreated with APAM. To evaluate the effect of the pH on the retention of the modified starch of the pulp, the pulp was treated with the modified starch at three different pH conditions. Pulp, APAM and PQA solutions were prepared as described above. The original pulp mixture was diluted to a concentration of 0.41% with deionized water. For the addition of 2.5 g of oven dry pulp, 605 g of the 0.41% solution was used for each condition. Three starch solutions were prepared as follows.

Modified starch with a pH of 10-7. 5 g (12.5% solids) of unmodified tapioca starch were diluted to 50 ml with a buffer solution having a pH of 10.

The starch was mixed well and allowed to stand for 1 hour. A volume of 12.5 ml of 0.1.5 ml of 0.1% Nalco 7527 was added and mixed well.

The solution was allowed to stand for a further 1 hour. The pH was then adjusted to 7 with 1 N sulfuric acid (about 2.7 ml).

The solutions were equilibrated for an additional 1 hour. The final concentration of the starch solution was 6.7%.

Modified starch with a pH of 10-10. 5 g (12.5% solids) of unmodified tapioca starch were diluted to 50 ml with a buffer solution having a pH of 10. The starch was mixed well and allowed to stand for 1 hour. A volume of 12.5 ml of 0.1% Nalco 7527 was added and mixed well. The solution was allowed to stand for 2 hours. The final concentration of the starch solution was 6.7%. 59 (12.5% solids) of unmodified tapioca starch was diluted Modified starch with a pH of 7-7. to 50 ml with a buffer solution having a pH of 7. The starch was mixed well and allowed to stand for 1 hour. 12.5 ml of 0.1% Nalco 7527 was added and mixed well.

The solution was allowed to stand for 2 hours. The final concentration of the starch solution was 6.7%.

Procedure in Britt drainage tank. APAM was added to the pulp in the Britt dewatering vessel, followed by mixing for 30 s, followed by addition of the starch slurry. For each experiment, 227 g (0.5 lb) (6.25 ml, (7.4 ml of a 6.74% solution) were added, the experiment was randomized, per ton of APAM 0.01% solution) and 20% starch and each condition was run 3 times. The results of the pH variation are summarized in Table 10.

TABLE 10 Filler retention in Britt drainage tanks: pH variation APAM / modified% filler retention pH10 / pH10 69 pH10 / pH7 75 pa? / PH7 77 10 15 20 25 30 521 309. . . In all of the conditions tested, a high retention of starch was obtained, with the pH = 7 / pH = 7 method giving slightly greater retention than the pH = 10 / pH = 10 method.

EXAMPLE 4 Preparation and properties of OCC containing representative starch with increased surface charge In this experiment, the preparation and properties of old corrugated board (OCC) containing modified starch are described. The properties of representative OCC products were determined and compared with OCC products that did not include modified starch.

The OCC product was prepared from a fiber-containing batch containing 100% OCC. Modified starch was prepared as described above by adding 2270 g (5 lb) of PQA (Nalco 7527) per ton of starch. (0.5 lb) APAM 171) per tonne of fiber, followed by the addition of 3% by weight The pulp was treated with 227 g (Accurac modified starch, based on the total weight of fibers, and then 2270 g (5 lb) CPAM (Accurac 182RS) fibers After depositing the batch containing the per ton of modified starch on a perforated support, the deposited pulp was dewatered and then dried to obtain 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 formed without the incorporation of modified starch, and Sample 2 refers to an OCC product which includes 3% by weight of modified starch. , based on the total weight of fibers. In the table, SCC, STFI and TEA refer to short-range STFI compression and tensile energy adsorption, respectively.

.I .Ä 24 ëmwmä: SJQ Sáï Ggwü Üæmm Hmïm qmm måmw mÄH ßåwmm mdm Qwv Håm fl Äæw må fl wJÄ N âß fl ïi âåï: ïwü írw fl wlwom Såå Tow wåmm miï Tamm m2? 33 miä mä: »iQ wJl H: EDBÜ um: Aweøïn fi ø fi v w E fi šï sšš Si En: E \ mx m flfifl E \ mx Hmßm mx ñcw fifl ßäv ~ E \ mx nwux fläm mx HG .amæ -xownum xowcH uw-m m m xHm. > owm ÜMQMOVTHWDW .UGMÜ fi WHUOÉ Ümu fl ß flfififl w flfifi DUO .HÜQÜMMQÜÜW aa QAWQQH 10 l5 20 25 30 b.) Ul 521 s09g¿ 25 Referring to Table 11, the explosive strength according to Mullen represents 2% of the OCC in the Mullen. similarly composed OCC without modified starch. Increases in short-distance STFI compression, traction and stretching were also observed. The OCC product containing the modified starch had an increase in short-term STFI compression of about 5%, an increase in elongation of about 9% and an increase in elongation of about 16% compared to similarly formulated OCC product without modified starch.

The weight percentage of starch retained in representative OCC products was compared with each other and with OCC products containing unmodified starch.

The results are summarized in Table 12-15. Several representative OCC products were prepared by varying the amount of cationic additive used to prepare the modified starch, the amount of modified starch added to the pulp batch and the type and amount of retention aid added to the pulp batch. The results of percent starch retention for various representative OCC products are summarized in Table 12. In these products, the cationic additive used to prepare the modified starch was PQA (Nalco 7527), the anionic retention aid was APAM (Accurac 171). the agent was CPAM and the cationic retention (Accurac 182). The following terms were used in Table 12: Modified starch refers to starch modified with 2270 g (5 lb) PQA (Nalco 7527) per ton of starch.

Variable PQA refers to an OCC product prepared by pre-treating the pulp with 227 g (0.5 lb) APAM (Accurac 171) per tonne of fiber before treatment with modified starch produced from starch and varying amounts of PQA (Nalco 7527).

A, B, C and D refer to OCC products containing modified starches prepared from 10 15 20 25 30 U.) Uï 521 so9: ßi§: ¿y „26 from 454 g (1 lb), 908 g (2 lb ), 1362 9. (3 lb), 2270 g (5 lb) and 3178 g (7 lb) PQA (Nalco 7527) per ton of starch.

Variable APAM refers to an OCC product prepared by pre-treating the pulp with varying amounts of APAM (Accurac 171), followed by modified starch treatment based on starch and 2270 g (5 lb) PQA (Nalco 7527) per tonne of starch.

E, F and G refer to OCC products in which (0.25 lb), 227 g of APAM (Accurac 171) pulp have been pretreated with 113.5 g (0.5 lb) and 340.5 g (0.75 lb) ) tonnes of fiber.

APAM / PQA / APAM refers to an OCC product in which pulp (0.25 lb) APAM 171) and subsequently treated with modified starch per batch was pretreated with 113.5 g (Accurac prepared from 2270 g (5 lb) ) PQA (Nalco 7527) per tonne of starch and 113.5 g (0.25 lb) APAM (Accurac 171) per tonne of fiber.

APAM / PQA / CPAM refers to an OCC product in which the pulp (0.25 lb) APAM 171), and subsequently treated with modified starch, the batch was pretreated with 113.5 g (Accurac prepared from starch and 2270 g (5 lb) PQA (Nalco 7527) per tonne of starch, followed (2.0 lb) CPAM (Accurac 182) per tonne of fiber.

Variable CPAM refers to an OCC product prepared from 908 g by treating the pulp with varying amounts of CPAM (Accurac 182) after treatment with modified starch prepared from starch and 2270 g (5 lb) PQA (Nalco 7527) per tonne of starch.

H, I and J refer to OCC products in which the pulp is treated with 454 g (1.0 lb), 908 g (2.0 lb) and 1362 g 83.0 lb) CPAM (Accurac 182) per ton of fibers. lO 15 521 309§f, ff {§§¿fj, ¿¿¿27 TABLE l2 Comparison of OCC starch retention OCC filler% Retention Starch 1.45 Modified starch 20.82 Variable PQA A 79.19 B 95.63 C 94.52 D 88.20 Variable APAM E 82.83 F 94.52 G 88.65 APAM / PQA / APAM 81.29 APAM / PQA / CPAM 76.45 Variable CPAM H 37.50 I 42.31 J 45, 42 The results in Table 12 show that the modified starch is strongly retained by pulp and that the retention of modified starch can be increased by the use of retention aids. The anionic retention aid provided an improvement in retention that was better than that of the cationic retention aid.

The weight percentage of the retained modified starch in representative OCC products as a function of the amount of cationic starch additive (PQA, Nalco 7527) per tonne (0.5 lb) retinal agent APAM, Accurac 1719 per tonne of fiber, starch, with pretreatment with 113.5 g anjo- was determined. The results are summarized in Table 13. 10 15 20 521 309 28 TABLE 13 OCC starch retention: PQA variance PQA g / ton (lb / ton)% retention 454 (l) 84.5 454 (1) 73.9 1362 (3 ) 87.7 1362 (3) 103.6 2270 (5) 94.5 2270 (5) 94.6 3178 (7) 88.8 3178 (7) 87.6 The results show that considerable retention was obtained by using from 454 g (l lb) to 3178 g (7 lb) PQA per ton of starch, with about 2270 g (5 lb) of PQA per ton of starch giving almost optimal retention.

The weight percent of the retained modified starch (2270 g (5 lb) representative OCC products as a function of pre-PQA per ton of starch) retained in treatment with varying amounts of anionic retention aid (APAM, Accurac 171) was determined. The results are summarized in Table 14.

TABLE 14 OCC starch retention: APAM variation APAM g / ton (lb / ton)% retention 113.5 (0.25) 79.5 113.5 (0.25) 86.1 227 (0.50) 94, 5 227 (0.50) 94.6 340.5 (0.75) 89.0 340.5 (0.75) 88.3 The results show that the optimal retention was obtained for pretreatment with 227 g (0.5O lb) anionic retention aid per tonne of fiber. 10 15 521 309 29 The percentage by weight of retention modified starch (2270 g (5 lb)) PQA per tonne of starch) in representative OCC products as a function of treatment with varying amounts of cationic retention aid (CPAM, Accurac 182 ) was decided. The results are summarized in Table 14.

TABLE 15 OCC starch retention: CPAM variation CPAM g / ton (lb / ton)% retention 454 (1) 27.1 454 (1) 47.9 908 (2) 42.5 908 (2) 42.2 1362 ( 3) 44.4 1362 (3) 46.5 The results show that significant retention was obtained by using from 454 (1 lb) to 1362 g (3 lb) CPAM per ton of starch.

Although the preferred embodiment of the invention has been elucidated and described, it should be understood that various changes may be made without departing from the spirit and scope of the present invention.

Claims (55)

10 15 20 25 30 U) U '| 521 309 30 PATENT REQUIREMENTS A composition comprising a polysaccharide particle and a cationic additive, wherein the cationic additive is bound to the polysaccharide particle to produce a polysaccharide particle with a positive surface charge. The composition of claim 1, wherein the cationic additive comprises a cationic polymer. The composition of claim 2, wherein the cationic polymer comprises a polyquaternary amine. The composition of claim 3, wherein the polyquaternary amine has a molecular weight in the range of from about 1 million to about 5 million g / mol. A composition according to claim 3, wherein the polyquaternary amine has about 3 milliequivalents of quaternary amine / g. The composition of claim 1, wherein the cationic additive is present in the composition in an amount from about 454 g (1 lb) to about 6810 g (15 lb) per ton of polysaccharide. The composition according to claim 1, wherein the surface charge is in the range from about + 1 mV to about + 100 mV. The composition of claim 1, wherein the polysaccharide is selected from the group consisting of corn, potato, tapioca, pea and wheat starch. A bulk kit comprising a polysaccharide particle with a positive surface charge, wherein the polysaccharide particle with a positive surface charge comprises a cationic additive bound to the polysaccharide particle. The kit of claim 9, wherein the cationic additive comprises a cationic polymer. 11. ll. The kit of claim 10, wherein the cationic polymer comprises a polyquaternary amine. A kit according to claim 9, wherein the polysaccharide portion has a surface charge in the range from about + 1 mV to about mV. F (D * Q O [I 10 15 20 25 30 35 521 309 31 A kit according to claim 9, further comprising an anionic retention aid. The kit of claim 9, further comprising a cationic retention aid. The kit of claim 13, further comprising a cationic retention aid. The kit of claim 13, wherein the anionic retention aid comprises an anionic polyacrylamide. The kit of claim 16, wherein the anionic polyacrylamide comprises a copolymer of acrylic acid and acrylamide. The kit of claim 17, wherein the copolymer comprises about 30 mole percent acrylic acid and about 70 mole percent acrylamide. The kit of claim 17, wherein the copolymer has a molecular weight in the range of from about 8 to about 15 million g / mol. The kit of claim 13, wherein the anionic retention aid is present in the kit in an amount from about 227 g (0.1 lb) to about 1362 g (3.0 lb) per ton of fibers. The kit of claim 14, wherein the cationic retention aid comprises a cationic polyacrylamide. The kit of claim 21, wherein the cationic polyacrylamide comprises a copolymer of acrylamide and a quaternary amine monomer. The kit of claim 22, wherein the copolymer comprises about 90 mole percent acrylamide and about 10 mole percent quaternary amine monomer. The kit of claim 22, wherein the copolymer has a molecular weight in the range of from about 8 to 15 million g / mol. The kit of claim 14, wherein the cationic retention aid is present in the kit in an amount from about 45.4 g (0.1 lb) to about 5448 g (12 lb) per ton of fibers. A paper product comprising a polysaccharide particle having a positive surface charge, wherein the polysaccharide particle has a positive surface charge comprising a cationic additive bound to the polysaccharide particle. 10 15 20 25 30 35 521 309 32 The paper product of claim 26, wherein the cationic additive comprises a cationic polymer. The paper product of claim 27, wherein the cationic polymer comprises a polyquaternary amine. The paper product of claim 26, wherein the polysaccharide particle has a surface charge in the range of from about +1 mV to about +100 mV. The paper product of claim 26, further comprising an anionic retention aid. The paper product of claim 26, further comprising a cationic retention aid. The paper product of claim 30, further comprising a cationic retention aid. The paper product of claim 30, wherein the anionic retention aid comprises an anionic polyacrylamide. The paper product of claim 31, wherein the cationic retention aid comprises a cationic polyacrylamide. A paper product according to claim 26, wherein the paper product is selected from the group consisting of fine paper, newsprint, bleached board, topcoat board, medium board and old corrugated board. A method of making a paper product comprising: adding a polysaccharide particle having a positive surface charge to a first pulp batch to provide a second pulp batch, the polysaccharide particle having a positive surface charge comprising a cationic additive bonded to polysaccharide particle : depositing the second batch of pulp on a perforated support to produce a wet web, and dewatering and drying the wet web to produce the paper product. The method of claim 36, wherein the cationic additive comprises a cationic polymer. lO 15 20 25 30 35 521 509 33 The method of claim 37, wherein the cationic polymer comprises a polyquaternary amine. The method of claim 36, wherein the starch particle has a surface charge in the range of about + 1 mV to about + 100 mV. The method of claim 36, further comprising adding an anionic retention aid to the first batch of pulp. The method of claim 36, further comprising adding a cationic retention aid to the first batch of pulp. The method of claim 40, further comprising adding a cationic retention aid to the first batch of pulp. The method of claim 40, wherein the anionic retention aid comprises an anionic polyacrylamide. The method of claim 41, wherein the cationic retention aid comprises a cationic polyacrylamide. A method according to claim 36, wherein the paper product is selected from the group consisting of fine paper, newsprint, bleached board, topcoat paper, medium board and old corrugated board. A method of increasing the strength of a paper product comprising: adding a polysaccharide particle having a positive surface charge to a first mass charge to produce a second mass charge, the polysaccharide particle having a positive surface charge comprising a cationic additive bound to the polysaccharide particle ; depositing the second batch on a perforated support to produce a wet web, and dewatering and drying the wet web to provide the paper product with increased strength compared to a similarly composed paper without the positive surface charge polysaccharide particle. 10 15 20 25 521 309 34 The method of claim 46, wherein the cationic additive comprises a cationic polymer. The method of claim 47, wherein the cationic polymer comprises a polyquaternary amine. The method of claim 47, wherein the polysaccharide particle has a surface charge in the range of about + 1 mV to about + 10 mV. The method of claim 47, further comprising adding an anionic retention aid to the first batch of pulp. The method of claim 47, further comprising adding a cationic retention aid to the first pulp batch. The method of claim 50, further comprising adding a cationic retention aid to the first pulp batch. The method of claim 50, wherein the anionic retention aid comprises an anionic polyacrylamide. The method of claim 52, wherein the cationic retention aid contains a cationic polyacrylamide. A method according to claim 46, wherein the paper product is selected from the group consisting of fine paper, newsprint, bleached board, cover layer board, medium board and old corrugated board.