KR20020060204A - Cationically modified polysaccharides - Google Patents

Abstract

The present invention provides a modified polysaccharide having an increased surface charge. The polysaccharide is modified to include a cationic polymer, preferably poly quaternary amine, having a surface charge of about +5 to about +20 mV. The denatured polysaccharides can advantageously be incorporated into papermaking finished stocks with increased retention.

Description

Cationicly modified polysaccharides {CATIONICALLY MODIFIED POLYSACCHARIDES}

One goal in paper manufacturing is to increase the amount of filler in the final product to reduce the amount of fiber, a relatively expensive component. Increasing the amount of filler should not adversely affect the sizing and other essential properties of the paper. Of the fillers, starch is of interest due to its low cost and availability. Generally, undenatured raw starch is poorly retained in paper finishes due to lack of effective interaction with fibers and retention aids. Despite these drawbacks, methods have been devised to utilize starch as filler in the papermaking process.

In most paper and cardboard production, the starch is fully cooked and used in a size press. Size press starches may include additives that provide desirable properties for paper or paperboard, such as improved printing, rigidity, bonding, dusting, surface picks, and the like. Cationic starch can typically be added at the paper machine wet end to improve the strength properties and fine particle retention of the paper. Other synthetic polymers can be combined with cationic starch to improve overall fine particle retention.

Raw starch particles that are neither heated nor denatured are added to the wet end of the paper machine due to unacceptably low retention. Raw starch has a near zero particle surface charge when mixed with water. This lack of surface charge results in weak interactions with charged retention aids and / or fibers. Without strong interactions (eg chemical adhesion), starch cannot be well retained in the papermaking system. Mechanical filtration of starch particles can retain some of the starch in the fibrous web, but such retention requires a special type of headbox arrangement.

However, by applying surface charge to the raw starch particles, starch retention in the web can be increased very effectively. Such increased starch retention is achieved through the use of retention aids that form a bridging attachment between the charged starch particles and the fiber surface. The application of charge to raw starch has already been achieved by chemical modification of starch through covalent attachment of certain functional groups to the starch, for example quaternary amine groups. In paper making, these chemically modified starches are typically fully heated and then added to the wet end of the paper machine. Such chemical denaturation methods add significant cost to starch and, moreover, do not produce starch with sufficient surface charge to improve the retention of unheated starch much more than the retention of unmodified raw starch.

Thus, there is a need for fillers that are economical for use in papermaking processes and allow for increased particle retention without adversely affecting sizing. There is also a need for fillers that have increased retention and additionally provide strength to paper products into which the filler is incorporated. The present invention seeks to meet these needs and provides further related advantages.

FIELD OF THE INVENTION The present invention relates to modified polysaccharides as fillers and reinforcements for paper and cardboard products, and more particularly to modified polysaccharides with increased surface charge.

The above-described aspects and many attendant advantages of the present invention are better understood by reference to the following detailed description, which will be more readily understood when explained in conjunction with the accompanying drawings.

1 is a schematic of representative modified polysaccharides formed in accordance with the present invention.

In one aspect of the invention there is provided a modified polysaccharide with increased surface charge. The polysaccharide of the present invention is a polysaccharide modified to include a cationic polymer. The modified starch formed according to the present invention has a surface charge from about +5 to about +20 mV. The modified polysaccharide may be incorporated into a papermaking finish while preferably having enhanced retention.

In another aspect of the present invention, a paper product is provided comprising a modified polysaccharide having an enhanced surface charge. Paper products comprising modified polysaccharides have similar strengths but have increased strength compared to paper products that do not contain modified polysaccharides. In one embodiment, the paper product includes cellulose fibers and modified polysaccharides. In another embodiment, the paper product further comprises a retention aid that enhances the retention of modified polysaccharides for the fibers. The retention aid can be any of a positive or negatively charged retention aid.

In another aspect of the present invention, there is provided a method of forming a modified polysaccharide having an increased surface charge and a method of forming a paper product having increased filler integrity and strength through incorporation of the modified polysaccharide.

In one aspect of the invention there is provided a polysaccharide with enhanced surface charge. The polysaccharide is modified to include a cationic additive that provides a positive charge on the surface of the polysaccharide. As used herein, the terms "polysaccharide" and "starch" may be used interchangeably, and the terms "modified starch" and "modified polysaccharide" refer to polysaccharides formed according to the present invention with increased surface charge.

Suitable cationic additives include materials that can be irreversibly and / or strongly connected to starch and, when connected to starch, can increase surface charge. Cationic additives include cationic organic polyelectrolytes and polymers. Preferably, the cationic additive comprises a cationic polymer such as poly quaternary amine. In a preferred embodiment, the cationic additive is a relatively low molecular weight, positively charged poly quaternary amine, which is about 1,000,000 to 5,000,000 g per mole and has a molecular weight in the range of about 3 meq (milliequivalents) per gram. . Such poly quaternary amines are commercially available under the name Nalco 7527 from Nalco Chemical Co., Naperville, Illinois. The cationic additive is present on the starch in an amount of about 1 to about 15 lbs per ton of starch, based on the dry state, preferably in an amount of about 5 lbs per ton of starch.

Other cationic additives useful for forming modified starch of the present invention include cationic polyacrylamide, aluminum sulfate, chitosan, polyamine, polyamidoamine, polyethyleneimine, polyamide-epichlorohydrin (PAE), polyalkylene polyamine- Epichlorohydrin (PAPAE), and amine polymer-epichlorohydrin (APE).

The modified starch formed according to the present invention has a surface charge in the range of about +1 mV to about +100 mV, preferably in the range of about +5 to about +20 mV, as determined by zeta potential measurement.

Starches from various raw materials can be modified to provide starch with increased surface charge. Suitable starch can be obtained, among other raw materials, in particular corn, potatoes, tapioca, peas and wheat.

The modified starch of the present invention may be formed from a slurry of unheated raw starch and cationic additives and water. In one embodiment, unheated raw starch is added to water at pH 10 to prepare a slurry having about 7% solids. Starch expands in alkaline solution and appears to be a milky paste. Although expansion occurs, starch remains in the form of discrete particles. However, at higher pH, the starch can become a gel as a result of denaturation (ie chemical heating). Gelatinization should be avoided while denatured starch is forming. Without being bound by the following theory, it is suggested that the cationic additive diffuses into the surface of the expanded starch particles to provide charged particles. The cationic additive is then held in the starch particles when the pH of the starch slurry treated with the cationic additive is adjusted to about neutral pH. When cationic additives are added, the starch's appearance changes from milky paste to granular granular particles. Alternatively, modified starch can be formed by adding a cationic additive to a starch slurry at about pH 7. Although the amount of expansion at neutral pH is less than that occurring at alkaline pH, it expands sufficiently to provide modified starch with increased surface charge. In a preferred embodiment, the modified polysaccharide is a granular polysaccharide.

A schematic of representative starch particles formed in accordance with the present invention is illustrated in FIG. 1. Referring to FIG. 1, the modified starch particle 10 includes a cationic additive 12 attached to the starch particle 14.

The preparation and properties of representative modified starches with increased surface charge are described in Example 1. The measurement of the surface charge of representative starch particles formed in accordance with the present invention with increased surface charge is described in Example 2.

The modified starch of the present invention may preferably be incorporated into a papermaking finished stock. As described below, the modified starch becomes an economical filler for paper products as the modified starch is strongly retained in the pulp. Moreover, paper products containing modified starch pulp have improved strength.

The retention of modified starch in pulp is increased compared to raw starch that is not heated. As described in Example 3, Britt Jar experiments showed that the modified starch could be retained in the pulp to the same or greater extent than the precipitated calcium carbonate (PCC), a conventional filler. In general, for fine paper furnish, denatured starch was retained from about 60 to about 70% under conditions of about 45% PCC.

The modified starch can be strongly retained in the pulp to provide pulp that can make paper products with high filler retention. Alternatively, in addition to modified starch, other retention aids may be added to the pulp to further increase the modified starch retention. Such retention aids include those known in the paper industry and the anion and cation retention aids described below.

Anionic retention aids or additives may be used to increase the modified starch retention. Anion retention aids include anionic organic polymer electrolytes and polymers. Preferably, anion retention aids include anionic polymers such as anionic polyacrylamide (APAM) and the like. In a preferred embodiment, the anion retention aid is a relatively high molecular weight, slightly negatively charged polyacrylamide. Preferred polyacrylamides have a molecular weight in the range of about 8,000,000 to about 15,000,000 g per mole, and are copolymers of acrylic acid (30 mol%) and acrylamide (70 mol%). Such polyacrylamides are commercially available under the name Accurac 171 from Cytec Industries Inc., West Paterson, NJ. Alternatively, anionic polyacrylamides are commercially available under the name Nugen 24 from Northwest Specialty Chemicals, Vancouver, Washington. The anion retention aid is present in the fibrous pulp in an amount of about 0.1 to about 3.0 lbs per ton fiber, preferably about 0.5 lbs per ton fiber.

Other suitable anion retaining aids include high molecular weight anionic flocculants.

As described in Example 3, representative anionic retention aids (e.g. APAM) are preferably added to the pulp at the wet end of the papermaking machine, before the addition of the modified starch, simultaneously with the addition of the modified starch, or after the addition of the modified starch. May be added to the pulp. As illustrated in Table 9, the largest retention (72% by weight) was achieved when APAM was added to pulp followed by modified starch. The second largest retention (58 wt%) was when modified starch was added to pulp followed by APAM. Both of these conditions provided higher filler retention than a typical alkaline fine paper system (45 wt.%).

Other additives may also preferably increase the retention of modified starch near the pulp. For example, cationic retention aids and additives can increase pulp retention for modified starch. Preferably, the cationic retention aid comprises a cationic polymer such as cationic polyacrylamide (CPAM), which has a relatively high molecular weight and is slightly charged with a cation. Preferred polyacrylamides have a molecular weight ranging from about 8,000,000 to about 15,000,000 g per mole and are copolymers of acrylamide (90 mol%) and quaternary amine monomers (10 mol%). Such polyacrylamides are commercially available under the name Accurac 182RS from Cytec Industries Inc., West Paterson, NJ. The cation retention aid is present in the fibrous pulp in an amount of about 0.1 to about 12 lbs. Per ton fiber, preferably from about 0.4 to about 6 lbs. Per ton fiber.

Other suitable cation retention aids include, for example, high molecular weight cationic flocculants such as cationic polyacrylamides available commercially under the names Nalco 7530 and 7520 from Nalco Chemical Co., Naperville, Ill. Included.

Pulps containing highly retained modified starch may advantageously be formed into paper products characterized by high filler retention and increased strength. Advantageously, paper products that benefit from the incorporation of modified starch include fine paper, newspaper paper, bleached board, liner board, medium board, and old corrugated cardboard (OCC). do.

Paper products containing modified starch and, optionally, one or more of the above-mentioned retention aids may be formed by adding modified starch and, if desired, retention aids to the pulp finished stock at the wet end of the papermaking machine. Depending on the properties of the desired paper product, the modified starch may be added to the pulp finished material in an amount of about 0.5 to about 20% by weight, preferably about 3 to about 10% by weight relative to the total weight of the fiber.

The flow characteristics of pulp finished stock, including the ability to dehydrate the finished stock, are important factors for high speed papermaking methods and machinery. One advantage of the present invention is that, despite the high retention of the modified starch in the finished stock, the addition of the modified starch to the pulp finished stock does not adversely affect the finished stock flow characteristics. Moreover, the finished stock is not adversely affected by the addition of the modified starch when the pulp is treated with the anion retention aid according to the present invention. The wet addition of modified starch to a pulp finished stock treated with an anion-holding adjuvant does not form a gum-like precipitate that negatively affects the quality of the pulp finished stock and limits its usefulness in high speed papermaking. Similarly, the addition of cation retention aids to pulp finishes containing anion retention aids and / or modified starches does not adversely affect pulp finishes.

The formation and properties of a representative paper product, OCC, containing modified starch are described in Example 4. Strength characteristics of representative OCC products are summarized in Table 11. The results show that the Mullen burst strength for OCC products containing 3% modified starch is increased by about 20% compared to OCC products with similar composition but lacking modified starch. Short ranges of compression STFI, increase in tension and elongation were also observed. OCC products had a short range of compression STFI increase of about 5%, tensile increase of about 9% and elongation increase of about 16% compared to OCC products of similar composition but lacking modified starch.

Representative OCC products also include (a) the amount of cationic additive used to make modified starch, (b) the amount of modified starch added to the pulp finish, and (c) the type of retention aid (s) added to the pulp finish. And varying amounts. Starch retention results for various representative OCC products are summarized in Table 12. Referring to Table 12, the results show that the modified starch is strongly retained by the pulp and the modified starch retention can be increased through the use of retention aids. Anionic retention aids provided a greater retention of cations than cation retention aids.

Example

Example 1

Preparation of Representative Starch with Increased Surface Charge

In this example, the production and physical properties of representative starches with increased surface charge are described. Representative starch comprising a poly quaternary amine (PQA), a cationic polymer, was prepared as described in set 1. Representative starch comprising a poly quaternary amine and further comprising a retention aid (APAM) was prepared as described in set 2.

Set 1 . Cationic potato starch (Accosize 80, commercially available from Cytec Industries Inc., West Patterson, NJ) was added to 3.85 with 1000 mL deionized water in a laboratory cooker (44 g, 86% solids). Heated as% solids. Representative cationic polymers in 0.1% solution (commercially available as low molecular weight, highly charged poly quaternary amines, PQA, name Nalco 7527 from Nalco Chemical Co., Naperville, Ill.) Dilute to 0.1% actives (1.43 g to 500 mL).

In each beaker 1, 2, 3, 5.71 g of unmodified tapioca starch (5.0 g O.D.) was diluted to 50 mL with pH 10 buffer and left for 30 minutes. Beaker 2 was added 0.95% heated cationic potato starch (1.25 g of 3.78% solution) and mixed well. Beaker 3 was added 5 lb / ton Nalco 7527 (12.5 g 0.1% solution) and mixed well. All three beakers were equilibrated for 30 minutes before microscopic observation.

All three beakers were then adjusted to pH 7 with 1N sulfuric acid and observed under a microscope. Three starch samples (1 mL of about 7% solids) at 10% by weight (based on O.D. pulp) were added at 1.0 g O.D. The pulp (hardwood bleached kraft pulp, HWBK, Aspen, disintegrated, commercially available from the Weihai user company) was added and mixed, respectively. Starch samples were observed under a microscope.

Set 2 . Cationic potato starch (Accosize 80) was heated to 4.5% solids in a laboratory cooker (69 g in 1340 mL deionized water, 86% solids). Nalco 7527 in 0.1% solution was diluted to 0.1% active ingredient (1.43 g diluted to 500 mL). A typical retention aid in 0.1% solution (commercially available under the name Accurac 171 from Cytec Industries Inc., West Paterson, NJ, high molecular weight, slightly negatively charged polyacrylamide) Dilute to% active ingredient (1.43 g diluted to 500 mL and diluted 10-fold).

In each beaker 1, 2, 3, 5.0 g unmodified tapioca starch (4.4 g O.D.) was diluted to 50 mL with pH 10 buffer and equilibrated for 15 minutes. Beaker 2 was added 1.3% cationic potato starch (Accosize 80) (1.25 g of 4.5% solution) and mixed well. Beaker 3 was added 5.7 lb / ton PQA (Nalco 7527) (12.5 g 0.1% solution) and mixed well. After chemical addition, the solutions were equilibrated for 30 minutes. All three beakers were then adjusted to pH 7 with 1N sulfuric acid and left for 1 hour.

Pulp treatment . Hardwood bleached kraft pulp (HWBK) was ground and diluted with deionized water to 0.25% concentration. To each of the six beakers was added 0.5 g of pulp at a 0.25% concentration. Three pulp samples were pretreated by adding 0.5 lb / ton (1.25 g of 0.01% solution) with APAM. The pulp was mixed well and then starch solution was added to the pulp samples. 0.5 lb / ton APAM (1.25 g of 0.01% solution) was then added to the untreated pulp sample and mixed. All six conditions were qualitatively analyzed under a microscope.

The first experiment was designed to quantitatively compare unmodified tapioca starch with heated cationic potato starch or cationic polymer, poly quaternary amine (PQA). Microscopy was used to observe physical changes or reactions with other starch particles or fibers. The microscopic observations are summarized in Table 1.

Table 1. Qualitative Microscopy

Beaker After chemical addition after pH adjustment Reaction with fiber 1 (control) No agglomeration No agglomeration No interaction 2 (cationic starch) Clumping slightly Clumping slightly Little interaction 3 (PQA) No agglomeration No agglomeration (highly dispersed) Little interaction

After addition of PQA and pH reduction, there was a marked difference in the reaction state of the starch slurry. Starch granules appeared to be highly dispersed. There was also some interaction between the modified starch and the fiber before and after pH adjustment. The addition of both heated starch and PQA allowed the starch particles to have some interaction when added to the fiber.

The effect on the modified starch solution reaction of the fibers pretreated or pretreated with anionic polymer (APAM) was also observed. In one case, APAM was added to the fiber before the starch slurry was added, and in other cases, APAM was added after the starch was added to the fiber. The observations are summarized in Table 2.

Table 2. Qualitative Microscopy

Beaker Fiber pretreated with APAM Fibers Post-treated with APAM 1 (control) No fiber interaction Starch particles evenly laid on the fibers 2 (cationic starch) Slight starch flocculation / fiber interaction Slight starch flocculation / fiber interaction 3 (PQA) No fiber interaction No fiber interaction

APAM treatment had a minor effect on the appearance of fibers treated with either cationic starch or PQA-modified starch.

Example 2

Surface charge measurement of representative starch particles with increased surface charge

In this example, a measurement of the surface charge of representative starch particles with increased surface charge is described. The charged surface was measured by zeta potential measurement.

Set 1 and 2: Control and Modified Starch . Each test was performed using unmodified tapioca starch. 50 mL pH 10 buffer was added to each starch sample (5.0 g) and the solution was left for 1 hour. After standing for 1 hour, 5 lb / ton (based on active ingredient) PQA (Nalco 7527) was added to the starch and mixed well to prepare a "modified sample". No polymer was added to the control sample. These samples were left to stand for an additional hour before adjusting to pH 7 with 1N sulfuric acid. These samples were left for 1 hour before being analyzed.

Set 3: modified starch with varying pH . Denatured samples were prepared by adding 5.0 g of unmodified tapioca starch to 50 mL pH 10 buffer (as described above), left for 1 hour and then 5 lb / ton PQA (Nalco 7527). After 1 hour, its pH was adjusted to pH 7 with 1N sulfuric acid and left for the last 1 hour. A second sample was prepared and left to stand by adding pH 10 buffer to 5.0 g of tapioca starch as received. After 1 hour 5 lb / ton PQA (Nalco 7527) was added and left to stand for another 2 hours without further pH adjustment. A third sample was prepared as described above except that pH 7 buffer was added to the starch without further pH adjustment.

Zeta potential measurement . Zeta potential for all samples using the Delsa 440 (Coulter Electronics, Inc., Hailer, FL) operating with a current equal to half the conductivity value of the sample over a frequency range of ± 500 Hz Was measured. The sample was run at two cell heights 16 and 84. Due to the addition of PQA, the samples were fairly well dispersed and analyzed after settling for 1 hour.

Zeta potential results from set 1 samples are shown in Table 3. The charge is the average at 8.6, 17.1, 25.6 and 34.2 ° angles at both 16 and 84 cell heights. The control (undenatured sample) was run three times and the denatured sample was run twice. The results show that the addition of cationic polyacrylamide resulted in a significant increase in charge in the denatured sample compared to the control.

Table 3. Starch Zeta Potential Measurement Results

Sample PQA (lb / ton) pH Conductivity (ms / cm) Average (mV) Control control 000 777 6.19.59.8 1.592.67-2.95 Metamorphosis 55 77 7.79.1 17.3518.22

Zeta potential results from set 2 are shown in Table 4. Since the settling in the zeta potential cell can change the stationary plane, experiments were conducted to test samples of various concentrations to determine the effect on charge analysis. After changing the concentration by changing the settling time of the starch slurry was analyzed. Samples were prepared as in the first set and included control and denaturing samples. The modified sample was also washed with deionized water to determine if the charge was on the surface of the particle or only weakly connected to the surface.

Table 4. Starch Zeta Potential Measurement Results

Starch PQA (lb / ton) pH Condition Conductivity (ms / cm) Settling time (minutes) Average (mV) Control control 000 777 Do not clean Do not wash Do not clean 6.969.759.82 0915 -2.08-2.19-2.47 Metamorphosis 555 777 Do not clean Do not clean 6.867.958.40 099 10.7215.2410.10

The results show that the settling time does not affect zeta potential measurements. The results further illustrate the fact that the charge is on the particle surface and not only weakly connected to the surface, and that cleaning the starch particles has a minor effect on the zeta potential measurement.

To determine the effect of pH on modified starch formation and on overall particle charge, three samples (Set 3 samples prepared as described above) were compared. The results are shown in Table 5.

Table 5. Effect of pH Adjustment on Charge

Starch 7527 (lb / ton) Initial pH Final pH Conductivity (ms / cm) Settling time (minutes) Average (mV) Metamorphosis 555 7107 7107 6.798.008.05 606060 17.2515.8618.29

The modified samples all had similar cation charges. It is not seen that pH adjustment had a significant effect on denaturing process surface charge.

Example 3

Pulp Retention of Typical Starch with Increased Surface Charge

In this example, the retention of the starch by the pulp side of a representative starch with increased surface charge is described. To determine if denatured starch could be retained at high shear conditions, Britt Jar was used for retention studies.

Pulp Production . Prince Albert hardwood was purified at 400 mL CSF using a Ischer Whisical Purifier (Bird Escher Wyss, Manfield, Mass.) Under the following conditions: 3.0% concentration, 1.0 Ws / m Specific edge load, 1250 rpm, 0.583 km / s cut length, and 60 degree bar angle. In addition, Prince Albert softwood was also purified with 600 mL CSF using Isher Whiskey, except that the specific edge load was 3.0 Ws / m. The net power specific energy for hardwood was 48.6 kW-h / t and 1.75 kW-h / t for softwood. A pulp blend of 60% hardwood and 40% softwood was prepared. Fines were removed using a 200 mesh screen box. The freeness value of the light-free pulp mixture was 695 mL at 2.2% concentration.

Britza conditions . A brit ruler with a 100 mesh cylindrical mesh screen was used for retention measurements. The pulp was added to a vaned Britt Jar with a stopper closed and mixed with starch at various speeds. After the time for sampling had elapsed, the stopper was opened and the filtrate collected in a tared aluminum pan (about 100 mL). The pan was weighed on the same four-place balance as was used to weigh the packaging immediately. The pan was placed in an oven at 105 ° C. until the next day. The dry sample was placed in a desiccator and the pan was weighed again. The concentration of slurry not retained was calculated by Formula 1.

(One)

Percentage retention from the pulp slurry was calculated using Equation 2.

(2)

To determine the exact shear angle or mixing speed, initial studies were done with typical alkaline fine paper finishes. The retention of starch formed according to the invention was compared with the retention of precipitated calcium carbonate.

Chemical substance . The pulp prepared as described above was diluted with deionized water to a concentration of 0.65%. Precipitated calcium carbonate (PCC) was obtained from Specialty Minerals, Inc. of Bethlehem, Pennsylvania and had a 31.6% solids. A highly charged, high molecular weight anionic polyacrylamide (APAM, Accurac 171) solution was prepared by diluting 1.43 g APAM with 500 mL of deionized water. The solution was mixed with a Brown Hand Blender for 15 seconds to prepare a 0.1% APAM solution and then diluted 10 × by diluting 50 mL of 0.1% with deionized water to 500 mL to prepare a 0.01% solution. Cationic potato starch (Accosize 80) solution was prepared by mixing 69.9 g of starch (86% solids) with 1340 mL of deionized water to 4.5% solids.

Britza procedure . Pulp (2.5 g, 385 g at 0.65% concentration) was added to the brits. Table 6 shows the mixing times for each addition along with the amount and amount of chemical addition to the pulp sample.

Table 6. Addition Sequence and Mixing Time of Chemicals

chemical substance Mix time (seconds) 17 lb / ton cationic starch (4.5% 0.47 g) 20% PCC (31.6% 1.58 g) 0.5 lb / ton APAM (0.01% 6.25 g) 151530

The conditions were run at three different mixing speeds, 500, 1000 and 1500 rpm, depending on the ultimate goal of achieving realistic filler retention. Typical filler retention on the fine paper machine was between 50-55%. Table 7 provides the mixing rate results.

Table 7. Brittle Filler Retention: Mixing Rate Variation

Mixing speed (rpm) Filler retention rate 50010001500 50.48.954.5

Referring to Table 7, the 500 rpm data set provided an effective retention, while at higher mixing speed conditions, it showed an inappropriate retention.

Modified starch retention

Retention rates for modified starch of the present invention were compared with typical alkaline fine paper finished stocks with PCC. APAM and cationic starch solutions were prepared as described above. In addition, 1.43 g raw material was diluted to 500 mL with deionized water to prepare a PQA solution (Nalco 7527). PQA solution was 0.1% active and mixed for 15 seconds in a brown hand blender. PCC was as described above. The pulp was diluted with deionized water to a concentration of 0.42%.

Denatured starch was prepared by diluting 5.0 g (12.5% solids) of unmodified tapioca starch to 50 mL with pH 10 buffer. The starch was mixed well and left to stand for 1 hour. 12.5 mL volume of 0.1% PQA (Nalco 7527) was added and mixed well. The solution was left to stand for another hour. The pH was then adjusted to pH 7 with 1N sulfuric acid (ca. 2.7 mL). The final concentration of starch solution was 6.7%.

Control starch was prepared by diluting 5.0 g (12.5% solids) of unmodified tapioca starch to 50 mL with pH 10 buffer. The starch was mixed well and left for 1 hour. 12.5 mL volume of deionized water was added and mixed well. The solution was left to stand for another hour. The pH was then adjusted to pH 7 with 1N sulfuric acid (ca. 2.7 mL). The final concentration of starch solution was 6.7%.

Britza procedure . For each Brittle experiment, 2.5 g pulp (595 g at 0.42% concentration) was added and mixed using 500 rpm. For control starch and modified starch, 6.5 g of 6.7% starch was added (17.4%). 6.25 mL of 0.01% solution was added for APAM (0.5 lb / ton) and 0.5 g of 4.5% solids for cationic potato starch (17 lb / ton). For PCC, 1.6 g of 31.6% solution was added (20%). Table 8 summarizes the conditions. Each condition was performed three times and the entire experiment was randomized (except for the first alkaline pine paper finish).

Table 8. Brittle Chemical Conditions

First addition Mixing time (s) Second addition Mixing time (s) 17.4% modified starch 30 No addition 30 17.4% modified starch 30 0.5 lb / ton APAM 30 0.5 lb / ton APAM 30 17.4% modified starch 30 17.4% control starch 30 No addition 30 17.4% control starch 30 0.5 lb / ton APAM 30 0.5 lb / ton APAM 30 17.4% control starch 30 17 lb / ton Cationic Starch / 20% PCC 15/15 0.5 lb / ton APAM 30

Filler (modified starch or PCC) retention is summarized in Table 9.

Table 9. Brittle Filler Retention: Addition Sequence Variation

Sample (first / second addition) Filler retention rate Control / APAM 5 Denaturation / APAM 58 Cationic Starch / PCC / APAM 45 APAM / Control 3 APAM / Degeneration 72 Control / No addition One Denaturation / no addition 10

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

Effect of Treatment pH on Modified Starch Retention

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

Modified starch pH 10-7 . 5 g (12.5% solids) of undenatured tapioca starch was diluted with pH 10 buffer to 50 mL. The starch was mixed well and left for 1 hour. 12.5 mL volume of 0.1% Nalco 7527 was added and mixed well. The solution was left to stand for another hour. The pH was then adjusted to pH 7 with 1N sulfuric acid (ca. 2.7 mL). The solution was equilibrated for one hour. The final concentration of starch solution was 6.7%.

Modified starch pH 10-10 . 5 g (12.5% solids) of unmodified tapioca starch was diluted to 50 mL with pH 10 buffer. The starch was mixed well and left for 1 hour. 12.5 mL volume of 0.1% Nalco 7527 was added and mixed well. The solution was left for 2 hours. The final concentration of starch solution was 6.7%.

Modified starch pH 7-7 . 5 g (12.5% solids) of unmodified tapioca starch was diluted to 50 mL with pH 7 buffer. The starch was mixed well and left for 1 hour. 12.5 mL of 0.1% Nalco 7527 was added and mixed well. The solution was left for 2 hours. The final concentration of starch solution was 6.7%.

Britza procedure . APAM was added to the pulp in the breech and then mixed for 30 seconds followed by the addition of starch slurry. For each run, 0.5 lb / ton APAM (6.25 mL 0.01% solution) and 20% starch (7.4 mL of 6.74% solution) were added. The experiment was randomized and each condition was run three times. The results for pH variation are summarized in Table 10.

Table 10. Brittle filler retention: pH fluctuations

APAM / Degeneration Filler retention rate pH10 / pH10 69 pH10 / pH7 75 pH7 / pH7 77

All conditions tested showed high retention of starch and the pH 7 / pH 7 method provided slightly higher retention than the pH 10 / pH 10 condition.

Example 4

Formation and Characterization of OCC Containing Representative Starch with Increased Surface Charge

In this example, the formation and properties of OCCs containing modified starch are described. The characteristics of representative OCC products were measured and compared with OCC products that do not contain modified starch.

OCC products were formed from fibrous finished stock containing 100 percent OCC. Modified starch was prepared as described above by adding 5 lb PQA (Nalco 7527) per ton of starch. The pulp finish was treated with 0.5 lb APAM (Accurac 171) per ton of fiber, followed by 3% by weight of modified starch based on the total weight of the fiber, followed by 5 lb CPAM (Accurac 182RS) per ton of fiber. The pulp finished stock containing modified starch was deposited on a foraminous support, and then the deposited pulp was dewatered and then dried to prepare an OCC product.

The properties of the OCC products prepared as described above are summarized in Table 11. In the table, sample 1 means OCC product formed without containing modified starch, and sample 2 means OCC product containing 3% by weight modified starch relative to the total weight of the fiber. In the table, SSC STFI and TEA mean a short range of compressed STFI and tensile energy absorption, respectively.

Table 11. Characteristics of OCC with modified starch

Sample# Basic weight lb / Msf Caliper Density kg / ㎥ Burst (Mullen) lbs Indices SSCSTFIlbs / in Indices Tensile lbs / in Indices kidney% TEAinlb / in ² 12 32.732.2 13.312.9 473.9481.1 5464 45.959.6 12.3512.8 11.311.9 21.924.6 20.122.9 2.7463.191 0.43790.5657

Referring to Table 11, for the Mullen burst strength for OCC Product Samples 1 and 2, the OCC with modified starch showed an increase of about 20% compared to OCC with similar composition but without modified starch. An increase was also observed in the short range of compression STFI, tensile and elongation. OCC products containing modified starch had a shorter range of compression STFI increase of about 5%, tensile increase of about 9%, and elongation increase of about 16% compared to OCC products of similar composition but without modified starch.

The weight percentages of starch retained in representative OCC products were compared to each other and to OCC products containing unmodified starch. The results are summarized in Table 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 finish, and the form and amount of retention aid added to the pulp finish. . Starch retention rates for various representative OCC products are summarized in Table 12. For these products, the cationic additive used to form modified starch was PQA (Nalco 7527), the anion retention aid was APAM (Accurac 171), and the cation retention aid was CPAM (Accurac 182). The following terms are used in Table 12:

Modified starch means starch modified with 5 lb PQA (Nalco 7527) per ton of starch;

Variable PQA means an OCC product prepared by pretreatment of pulp finish with 0.5 lb APAM (Accurac 171) per ton of fiber followed by starch and modified starch prepared from variable amounts of PQA (Nalco 7527): A , B, C and D mean OCC products containing modified starch made from 1, 3, 5, 7 lb PQA (Nalco 7527) per ton of starch;

Variable APAM means an OCC product prepared by pretreatment of pulp finish with variable amounts of APAM (Accurac 171) followed by modified starch made with 5 lb PQA (Nalco 7527) per ton of starch and starch: E , F and G mean OCC products pretreated with pulp finished stock with 0.25, 0.50 and 0.75 lb APAM (Accurac 171) per tonne of fiber;

APAM / PQA / APAM is pretreated with 0.25 lb APAM (Accurac 171) pulp finish, then modified starch made with 5 lb PQA (Nalco 7527) per ton of starch and starch, then 0.25 lb per ton fiber OCC products treated with APAM (Accurac 171);

APAM / PQA / CPAM is pretreated with 0.25 lb APAM (Accurac 171) pulp finish, then modified starch made from 5 lb PQA (Nalco 7527) per ton of starch and starch, followed by 2.0 lb per ton fiber OCC products treated with CPAM (Accurac 182);

Variable CPAM means an OCC product made by treating pulp finish with modified starch made with starch and 5 lb PQA (Nalco 7527) per ton of starch prior to treatment with variable amounts of CPAM (Accurac 182): H , I and J mean OCC products treated with pulp finished stock with 1.0, 2.0 and 3.0 lb CPAM (Accurac 182) per tonne of fiber.

Table 12. OCC Starch Retention Rate Comparison

OCC Filler Retention Starch 1.45 Modified starch 20.82 Variable PQAABCD 79.1995.6394.5288.20 Variable APAMEFG 82.8394.5288.65 APAM / PQA / APAM 81.29 APAM / PQA / CPAM 76.45 Variable CPAMHIJ 37.5042.3145.42

The results in Table 12 show that the modified starch is highly retained in the pulp and the modified starch retention can be increased through the use of retention aids. Anion retention aids provided greater retention rates than cation retention aids.

As a function of the amount of starch cationic additive (PQA, Nalco 7527) per ton of starch, the percentage by weight of modified starch retained in representative OCC products pretreated with 0.5 lb anion retention aid (APAM, Accurac 171) per ton of fiber Was measured. The results are summarized in Table 13.

Table 13. OCC Starch Retention: PQA Variation

PQA (lb / ton) Retention 11 84.573.9 33 87.7103.6 55 94.594.6 77 88.887.6

The results show that significant retention was achieved using 1-7 lb PQA per tonne of starch, with about 5 lb PQA per tonne of starch providing a near optimum retention.

The weight percentage of modified starch (5 lb PQA / ton starch) retained in a representative OCC product was measured as a function of pretreatment with varying amounts of anion retaining aid (APAM, Accurac 171). The results are summarized in Table 14.

Table 14. OCC Starch Retention: APAM Fluctuations

APAM (lb / ton) Retention 0.250.25 79.586.1 0.500.50 94.594.6 0.750.75 89.088.3

The results show that optimal retention was achieved when pretreated with 0.50 lb anion retention aid per tonne of fiber.

The weight percentage of modified starch (5 lb PQA / ton starch) retained in representative OCC products as a function of treatment with varying amounts of cationic retention aid (CPAM, Accurac 182) was measured. The results are summarized in Table 15.

Table 15. OCC Starch Retention: CPAM Change

CPAM (lb / ton) Retention 11 27.147.9 22 42.542.2 33 44.446.5

The results show that significant retention was achieved using 1-3 lb CPAM per tonne of starch.

While the preferred embodiments of the present invention have been illustrated and described, it will be understood that various changes may be made without departing from the spirit and scope of the invention.

Included in the detailed description.

Claims (55)

A polysaccharide particle and a cationic additive, wherein the cationic additive is attached to the polysaccharide particle to provide a polysaccharide particle having 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 poly quaternary amine. The composition of claim 3, wherein the poly quaternary amine has a molecular weight in the range of about 1,000,000 to about 5,000,000 g per mole. The composition of claim 3, wherein the poly quaternary amine has about 3 meq quaternary amines per gram. The composition of claim 1, wherein the cationic additive is present in the composition in an amount of about 1 to about 15 lbs per ton of polysaccharide. The composition of claim 1, wherein the surface charge is in the range of 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, peas and wheat starch. And a polysaccharide particle having a positive surface charge, wherein the polysaccharide particle having a positive surface charge comprises a cationic additive attached to the polysaccharide particle. 10. The pulp finish stock according to claim 9, wherein the cationic additive comprises a cationic polymer. 11. The pulp-finish material of claim 10, wherein the cationic polymer comprises a poly quaternary amine. 10. The pulp finishing material of claim 9 wherein said polysaccharide particles have a surface charge in the range of about +1 mV to about +100 mV. 10. The pulp finished stock according to claim 9, further comprising an anion retaining aid. 10. The pulp finished stock according to claim 9, further comprising a cation retention aid. The pulp finished stock according to claim 13, further comprising a cation retention aid. 15. The pulp finished stock according to claim 13, wherein the anion retention aid comprises an anionic polyacrylamide. 17. The pulp finished stock according to claim 16, wherein the anionic polyacrylamide comprises a copolymer of acrylic acid and acrylamide. 18. The pulp finishing material of claim 17, wherein the copolymer comprises about 30 mole percent acrylic acid and about 70 mole percent acrylamide. 18. The pulp finishing material of claim 17, wherein the copolymer has a molecular weight in the range of about 8,000,000 to about 15,000,000 g per mole. 15. The pulp finished stock according to claim 13, wherein the anion retaining aid is present in the finished stock in an amount of about 0.1 to about 3.0 lb per ton fiber. 15. The pulp finished stock according to claim 14, wherein the cationic retention aid comprises cationic polyacrylamide. 22. The pulp finished stock according to claim 21, wherein the cationic polyacrylamide comprises a copolymer of acrylamide and a quaternary amine monomer. The pulp finishing material of claim 22 wherein the copolymer comprises about 90 mol% acrylamide and about 10 mol% quaternary amine monomers. The pulp finishing material of claim 22 wherein the copolymer has a molecular weight in the range of about 8,000,000 to about 15,000,000 g per mole. 15. The pulp finished stock according to claim 14, wherein the cationic retention aid is present in the finished stock in an amount of about 0.1 to about 12 lbs per ton of fiber. A paper product comprising polysaccharide particles having a positive surface charge, wherein the polysaccharide particles with a positive surface charge comprise a cationic additive attached to the polysaccharide particles. 27. The paper product of claim 26, wherein the cationic additive comprises a cationic polymer. 28. The paper product of claim 27, wherein the cationic polymer comprises a poly quaternary amine. 27. The paper product of claim 26, wherein the polysaccharide particles have a surface charge in the range of about +1 mV to about +100 mV. 27. The paper product of claim 26, further comprising an anion retention aid. 27. The paper product of claim 26, further comprising a cationic retention aid. 31. The paper product of claim 30, further comprising a cationic retention aid. 31. The paper product of claim 30, wherein the anion retention aid comprises an anionic polyacrylamide. 32. The paper product of claim 31, wherein the cationic retention aid comprises cationic polyacrylamide. 27. The paper product of claim 26, wherein the paper product is selected from the group consisting of fine paper, newspaper paper, bleached paper, liner paper, corrugated paper, and old corrugated cardboard (OCC). Adding a polysaccharide particle having a positive surface charge to the first pulp finish stock, the cationic additive attached to the polysaccharide particles, to provide a second pulp finish stock; Depositing the second pulp finished stock onto an open support to provide a wettable web; And Dewatering and drying the wettable web to provide a paper product. 37. The method of claim 36, wherein the cationic additive comprises a cationic polymer. 38. The method of claim 37, wherein the cationic polymer comprises a poly quaternary amine. The method of claim 36, wherein the starch particles have a surface charge in the range of about +1 mV to about +100 mV. 37. The method of claim 36, further comprising adding an anion retention aid to the first pulp finished stock. 37. The method of claim 36, further comprising adding a cationic retention aid to the first pulp finished stock. 41. The method of claim 40, further comprising adding a cationic retention aid to the first pulp finished stock. 41. The method of claim 40, wherein the anion retention aid comprises an anionic polyacrylamide. 42. The method of claim 41 wherein the cation retention aid comprises cationic polyacrylamide. 37. The method of claim 36, wherein the paper product is selected from the group consisting of fine paper, newsprint, bleached paper, liner paper, corrugated paper and OCC. Adding a polysaccharide particle having a positive surface charge to the first pulp finish stock, the cationic additive attached to the polysaccharide particles, to provide a second pulp finish stock; Depositing the second pulp finished stock onto an open support to provide a wettable web; And Dewatering and drying the wettable web to provide a paper product of increased strength compared to paper that is similar in composition but lacks polysaccharide particles having a positive surface charge. 47. The method of claim 46, wherein the cationic additive comprises a cationic polymer. 48. The method of claim 47, wherein the cationic polymer comprises a poly quaternary amine. 48. The method of claim 47, wherein the polysaccharide particles have a surface charge in the range of about +1 mV to about +100 mV. 48. The method of claim 47, further comprising adding an anion retention aid to the first pulp finished stock. 48. The method of claim 47 further comprising adding a cationic retention aid to the first pulp finished stock. 51. The method of claim 50, further comprising adding a cationic retention aid to the first pulp finished stock. 51. The method of claim 50, wherein the anion retention aid comprises an anionic polyacrylamide. 53. The method of claim 52, wherein the cationic retention aid comprises cationic polyacrylamide. 47. The method of claim 46, wherein the paper product is selected from the group consisting of fine paper, newsprint, bleached paper, liner paper, corrugated paper and OCC.