MXPA01002635A - Combination of starch and polymer used in papermaking - Google Patents

Abstract

The present invention discloses paper having improved retention properties made by the addition to the papermaking system of a combination of cationic starch and starch phosphate, the starch combination having a select net zeta potential.

Description

STARCH POLYMER COMBINATIONS USED IN THE MANUFACTURE OF PAPER DESCRIPTION OF THE INVENTION This invention relates to an improved papermaking process wherein the polymer combinations of cationic and anionic starches have a selective zeta potential that is added to the pulp or the raw materials in the wet part to provide improved retention as well as drainage and strength properties. The term "paper" as used herein, includes laminar masses and products molded from fibrous cellulosic material, which may be derived from natural, synthetic sources such as polyamides, polyesters, rayon and polyacrylic resins as well as mineral fibers such as asbestos and glass. In addition, paper made from combinations of cellulosic and synthetic materials can be applied herein. Cardboard is also included within the broad term "paper". Papermaking, as conventionally known, is a process for introducing an aqueous slurry of pulp or wood cellulosic fibers (which have been churned or refined to achieve a level of fiber hydration and to which a variety of functional additives can be added. ) on a screen or similar device in such a way that the water is removed, thereby forming a sheet of consolidated fibers, which with pressure and drying can be processed in dry lamination or in the form of sheets. Two well-known papermaking processes involve the Fourdriner machine, the most common, and the cylindrical machine. In Fourdrinier and multiple cylinder operations, and in other machine operations, as is typical in papermaking, the feed or inlet to the machine is an aqueous slurry or suspension in water of fibers in pulp that are provided from of what is called the "wet part" system. In the wet part, the pulp together with other additives are mixed in an aqueous paste and subjected to mechanical and other operations such as beating and refining to improve the interfiber bond and other physical properties of the finished sheet. Additives commonly introduced together with the pulp fibers are pigments such as titanium dioxide, mineral fillers, such as clay and calcium carbonate and other materials introduced into a paper to achieve such properties as improved brilliance, opacity, uniformity, ink receptivity, fire retardancy, water resistance, increased volume, etc. It has been known that adding various materials, including starch, to the pulp or pulp in the papermaking process, or prior to the formation of the sheet, aids in the properties of retention, drainage and strength. Starch has been used in the paper industry for many years and in fact, it is the second largest volume raw material component in paper. Starches perform a number of functions in papermaking that include improvement in strength, increased drainage and increased retention of fibers, fines and other components in the endless belts. Both modified and unmodified types have been used. Anionic and cationic starches as well as amphoteric starches have long been used as additives in papermaking for their contributions to the strength and retention of pigment in paper. See, for example, U.S. Patent Nos. 3,459,632 issued to C. Caldwell et al. On August 5, 1969 and 3,562,103 issued to K. Moser et al. On February 9, 1971. The most recent patents involve the use of starches in papermaking including U.S. Patent 4,876,336 issued to D. Solarek et al., October 24, 1989, which describes the use of amphoteric starch derivatives and U.S. Patent 5,129,989 issued to S. Gosset et al. ., July 14, 1992, which describes the use of cationic and anionic starches in separate additions. Despite the diverse and well-known uses of different starches in papermaking, there is a continuing need and desire to provide improved papermaking properties and especially improved retention. Now, it has been found that significantly improved retention properties can be obtained in the papermaking process by the addition or combination of cationic starch and starch phosphate having a selective zeta potential, for the pulp or the raw materials in the wet part. More particularly, this invention involves the process for making paper which comprises adding to the pulp or raw materials before or during the formation of the sheet, a combination of cationic starch and starch phosphate, the combination having a zeta potential of about +20. -18 mV (millivolts). In another embodiment of this invention, the paper is made using the combination of cationic starch and starch phosphate having a selective zeta potential as described herein, and wherein the starch phosphate is made by impregnating the starch with a reactive phosphate and then drying at substantially anhydrous conditions, preferably while in a fluidized state, before heat treatment to effect phosphorylation. Preferably both the drying and heat treatment occur while in the fluidized state. This invention involves a combination of modified cationic starches and starch phosphates in amounts to provide a range of zeta potential selected for use in papermaking. The modified starches that are used in this invention can be prepared by methods known and described in the art. The cationization of starch can be produced by well-known chemical reactions with reagents containing amino, imino, ammonium, sulfonium and phosphonium groups as described, for example, in "Cationic Starches" by DB Solarek, Modified Starches: Properties and Uses, Chapter 8 , pp. 113-129, 1986, and US Patent No. 4,119,487 issued October 10, 1978 to M. Tessler Such cationic derivatives include those containing nitrogen groups comprising primary, secondary, tertiary and quaternary amines and sulfonium and phosphonium groups linked by ether or ester bonds. Preferred derivatives are those containing the tertiary amino ether and quaternary ammonium groups. The general method for preparing starches containing tertiary amine groups, which method involves reacting the starch under alkaline conditions with a dialkylaminoalkyl halide is described in US Patent 2,813,093 issued November 12, 1957 to C. Caldwell, et al. Another method, therefore, is described in U.S. Patent No. 4,675,394 issued on January 23, 1987 to D. Solarek et al. The primary and secondary amine starches can be prepared by reacting the starch with aminoalkyl anhydrides, amino epoxides or halides, or the corresponding compounds having aryl in addition to the alkyl groups. The quaternary ammonium groups may be introduced into the starch by suitable treatment of the ether or tertiary aminoalkyl starch, as described in the aforementioned US Patent No. 2,813,093. Alternatively, the quaternary groups can be introduced directly into the starch by treatment with the reaction product of an epihalohydrin and a tertiary amine and tertiary amine salt, to provide, for example, ether substituent groups of (3-trimethylammonium chloride) - 2-hydroxypropyl as described in U.S. Patent No. 4,119,487. The patents cited above, for example, '487,' 093 and '394 are incorporated herein by reference. The preparation of cationic sulfonium derivatives is described in U.S. Patent No. 2,989,520 issued June 1961 to M. Rutebberg et al., And essentially involves the reaction of starch in an aqueous alkaline medium with a beta-haloalkylsulfonium salt, vinylsulfonium salt or epoxyalkylsulfonium salt. The preparation of cationic phosphonium derivatives is described in U.S. Patent No. 3,077,469 issued February 12, 1963 to A. Aszalos and involves the reaction of starch in an aqueous alkaline medium with a beta-haloalkylphosphonium salt. The patents cited previously, namely '520 and' 469 are incorporated herein by reference. Other suitable cationic starches can be provided using reagents and methods that are well known in the art as illustrated in the references above. Further description of useful cationic starches is disclosed in US Patent No. 2,876,217 issued March 3, 1959 to E. Paschall, US Patent No. 2,970,140 issued January 31, 1961 to C. Hullinger et al., US Patent No. 5,004,808 issued on April 2, 1991 to M. Yalpani et al., US Patent No. 5,093,159 issued March 3, 1992 to J. Fernandez et al., And EP 406 837 published January 1, 1991, corresponding to US Application Serial No. 516,024 filed April 26, 1990), all of which are incorporated herein by reference. Particularly, useful cationic derivatives are those containing amino or nitrogen groups having alkyl, aryl, aralkyl or cyclic substituents of up to 18 carbon atoms and especially alkyl of 1 to 6 carbon atoms. The amount of cationic substituent in the starch can be derived and generally a degree of substitution (DS) of up to about 0.003 to 0.2 and preferably of about 0.01 to about 0.1 will be used.

Although large amounts of cationic substituents or higher substitution grades (DS) may be used, they are more expensive and difficult to manufacture and therefore not economically attractive. The term "degree of substitution" (DS) as used herein, means the average number of substituent sites or groups per anhydroglucose unit of the starch molecule. The anionic starch used in this invention is a monoester of phosphate starch. The starch phosphate can be prepared by phosphorylation using any known method including reaction with various inorganic phosphate salts. The preparation of starch phosphate monoesters using such methods is described in "Phosphorilated Starch and Miscellaneous Inorganic Esters" by D.B. Solarek, Modified Starches: Properties and Uses, Chapter 7 pp. 97-112, 1986. The phosphate groups are introduced into the starch by thermal reaction with water soluble ortho-, pyro-, meta-, or tripolyphosphates. The phosphate reactants illustrated are alkali metal phosphates such as potassium and sodium ortho-phosphate, phosphoric acid, phosphorus oxychloride, sodium potassium tripolyphosphate and potassium and sodium trimetaphosphate. The reagent may be either a mono-, di- or trialkyl metal phosphate or combinations thereof. Techniques for the phosphorylation of a starch base are further described in U.S. Patent Nos. 2,824,870 issued February 25, 1959 to H. Neukom and 2,961,440 issued November 22, 1960 to R. Kerr. These patents describe techniques for reacting starch with heat impregnated with a phosphate salt of an alkali metal, within a range of pH described. The aforementioned US Patent 3,562,103 directed to anionic phosphate groups containing starches, describes a method of starch phosphorylation comprising forming an aqueous starch paste at room temperature and adding an appropriate concentration of phosphate reagent. Preferably, the pH is adjusted between 4 and 6, although it is established that a range of 4 to 11.5 can be used. The starch is filtered without washing and adjusted to a moisture level of about 20% or less, preferably about 5 to 20% by weight at a temperature of less than about 70 ° C. The starch phosphate composition is then heated to a temperature of 100 to 160 ° C until the product has the desired level of anionic phosphate groups. The '870,' 440 and '103 patents previously cited are all incorporated herein by reference. In the North American Patent No. 4,166,173 issued on August 28, 1979 to O.B. Wurzburg et al., The disclosure of which is incorporated herein by reference, starch is phosphorylated by an improved pollution free process involving the formation of a concentrated alkali metal tripolyphosphate salt reagent solution and impregnated therewith a starch cake Containing no more than 45% by weight of moisture. Drying and thermally reacting the starch thus impregnated provides the phosphorylated starch. In the preparation, the concentrated reagent solution during the addition of the tripolyphosphate salt to water 1 or more acids are added to control the pH between 2.8 and 5.0. For the purpose of this invention, any starch containing phosphate, natural or modified can be used. For the modified product, the phosphorylation can be carried out by any known technique with the thermal reaction of the starch impregnated with phosphate which is carried out at a pH between 5.5 and 8.5, and preferably 6.0 to 8.5. The reaction of the starch can be carried out, for example, sodium or potassium tripolyphosphate salts, sodium or potassium hexametaphosphate and sodium or potassium pyrophosphate which produce orthophosphate monoester groups, ie, mono-starch phosphates. Other alkali metal salts can be used in place of sodium or potassium which are preferred as the phosphorylation reagent. In this way, by carrying out phosphorylations employing an aqueous starch paste, the pH of the starch paste containing the phosphorylation reagent is adjusted to about 5.5 to 8.5. The use of pH levels below about 5.5 will result in a degraded starch while the use of enzyme pH levels of about 8.5 may produce undesirable crosslinking. If phosphorylation is carried out by spreading the reagent, a starch paste is prepared in an ordinary manner and adjusted to be within the designated pH range and then filtered. The reagent is spread on the starch cake with adjusted pH. The practitioner will recognize that it is also possible to prepare the filter cake at a slightly alkaline pH and impregnate it with an acidic solution of phosphate reagent so that in the end the pH of the phosphate-starch reagent mixture is within the defined pH range. The specific reagent used may require adjustments of pH levels. For example, sodium tripolyphosphate (STP) has limited solubility in water (0.2 g / cc at 25 ° C). In order to achieve the highest solids solutions, the pH is maintained from 4.0 to 6.0 by the addition of acid such as HCl or H3P04 during the dissolution of the salt. In contrast, sodium hexametaphosphate (NaP03) 6 shows very high solubility and concentrated solutions (20 to 36% by weight) can be prepared without any pH adjustment. The starch phosphate suitable for this invention will include about 0.03 to 1.0% bound phosphorus, preferably about 0.1 to 0.5% by weight, based on the weight of the dried starch. By the term "bound phosphorus" is intended to mean that the phosphorus which is bound by an ester bond to a hydroxyl group of the anhydroglucose base of the derived starch. The bound phosphorus can also be defined as phosphorus that can not be removed from the product by conventional washing or separation techniques. Most commonly, the amount of phosphorylation reagent employed will vary from about 0.5 to 12% by weight, based on the weight of the dried starch. For example, treatment of waxy corn with 3.5 to 4.0% sodium tripolyphosphate will give a starch containing 0.14 to 0.22% bound phosphorus. The starch cake containing the phosphorylation reagent is dried to a moisture of less than about 9.0% and preferably from about 2.0 to 7.0% before the required heat treatment at elevated temperatures. Ordinarily, the dry phosphorylation reagent starch mixture is heated to temperatures of about 110 ° to 140 ° C and preferably will vary from about 130 ° to 135 ° C during the phosphorylation reaction. The heating period can vary from 0.1 to 4 hours or more depending on the selected reagent, pH, temperature, etc. The phosphorylation step is performed under conditions that prevent severe molecular degradation, as would be shown by a significant decrease in the viscosity of the starch. As described above, while any phosphate containing starch can be used in this invention, a particularly useful starch phosphate is one which is made by impregnating the starch with phosphate and then drying at substantially anhydrous conditions before the heat treatment for effect phosphorylation. By anhydrous or substantially anhydrous conditions it is meant that less than about 1% by weight of the moisture content, based on the weight of the dried starch. It is preferred that both the drying and phosphorylation steps occur in the fluidized state. While other drying and phosphorylation systems can be used, which are not in the fluidized state, the fluidized state is preferred because it provides excellent heat and mass transfer resulting in good and desired reaction drying characteristics. Impregnation by the phosphate reagent can be achieved by adding the reagent to a level of less than about 15% and preferably less than about 10% by weight, based on the weight of the dry starch, either in the dry state or in the wet starch, or by dissolving the reactant in water to form an aqueous solution which is then mixed with the starch. These impregnation techniques are described in U.S. Patent Nos. 4,166,173 cited above, and 4,216,310 issued August 5, 1980, to O. Wurzburg et al., Both of which are incorporated herein by reference. The impregnated starch is first subjected to the fluidized state and dried at anhydrous conditions of less than about 1% by weight of the moisture content based on the weight of the starch, at less than about 140 ° C more particularly between about 60 to 140 ° C , preferably between about 100 to 125 ° C. The dried product, while still in the fluidized state, is heated between about 100 to 185 ° C, preferably between about 120 to 140 ° C for about 30 to 300 minutes, at elevated temperatures of about 150 ° C, the time of processes is preferably less than about 45 minutes. The method and conditions for the impregnation and phosphorylation of the starch for the operation where the impregnated starch is dried to anhydrous conditions and then phosphorylated while in the fluidized state, can be the same as in the previously described known methods. The fluidized state is achieved by vigorously mixing the solid starch particles under vacuum or in a gas whereby a uniform distribution of starch through the vacuum or gas can be obtained. Vigorous mixing can be achieved using air or gas, at or above atmospheric pressures in a fluidized bed reactor or by sufficient mechanical agitation. Where pressurized gas is used to effect the fluidized state, the velocity of the gas must be achieved at a minimum speed so that the particles are free to move and show a "fluidized state". The fluidized state results in a very efficient heat transfer and allows the starch to dry rapidly in a virtually anhydrous state at a low temperature. The phosphate esters prepared by pre-drying to anhydrous conditions while in the fluidized state, as described above, are characterized by improved purity as the high reaction efficiency provides a product with a high level of substitution while which provides a low level of residual inorganic phosphate salts in the final starch phosphate monoester products. In addition, the process decreases undesirable side reactions such as starch hydrolysis and crosslinking. Such products are also characterized by improved viscosity, color and uniformity. The new process also retains the granular integrity of the starch advantageously allowing the optional washing of the final product. The starch phosphate prepared, as described above, which uses anhydrous conditions and the fluidized state involves a process that has improved reaction efficiency. The reaction efficiency is defined as the amount of bound phosphorus divided by the total amount of phosphorus used in the process, multiplied by 100. The phosphorus content can be measured by any suitable conventional analytical technique such as inductively coupled plasma (ICP) or gravimetric analysis. The reaction efficiencies of this process can be as high as about 70 to 85% or more, and is much improved with the reaction efficiency of traditional methods of phosphorylation starches. The process for preparing the starch phosphates by impregnating the starch with a phosphate reagent and then drying under anhydrous conditions while in a fluidized state before heat treating is described in further detail in co-pending US Patent Application # 1878, entitled "Improved Starch Phosphates Ester Composition, Process and Method of Uses in Food "by Wolfgang Bindzus et al., As inventors, filed on the same date as this application.The process and details of this process are described in this North American application # 1878 which is incorporated herein. reference The starch that can be used as the base material of the modified cationic starch and the anionic starch materials of this invention can be derived from any plant source including corn, potato, wheat, rice, waxy rice, tapioca, waxy corn, sago , sorghum, starch with high amylose content such as amylose corn having 40% or more of amylose content, etc. Starch flours can also be used.The conversion products derived from any of the following are also included: includes, for example, dextrins prepared by the hydrolytic action of acid and / or heat; oxidized starches prepared by treatment with oxidants such as sodium hypochlorite; fluency or thin boiling starches prepared by the conversion of enzymes or hydrolysis of mild acid; derived or modified starches; and cross-linked starches. The preferred starches are waxy corn, corn, tapioca, potato starch and combinations thereof. The starch base can be a granular starch or a gelatinized starch, i.e. non-granular starch. It is further mentioned that the starch base material can be the same or different for each of the components of cationic starch or anionic starch. While the amount of modification, i.e. the cationic substitution and the anionic substitution in the respective starch components can vary as mentioned in the foregoing, the characteristic The respective components of the two components are provided in such proportions that the net zeta potential of the starch combination will be in the range of about +20 to -18 mV and preferably of about +15 to -5 mV. Maintaining the zeta potential within this range is important because when the combination of starch is used with a papermaking process, significant improvement in retention of the filler is observed as well as good drainage and strength properties. When the papermaking process employs the cationic starch and the combination of anionic starch phosphate according to this invention, it involves an alkaline papermaking system, ie, where the pH of the system is typically greater than about 6.5, the combination of starch will more particularly have a zeta potential of about +18 to -18 mV and preferably about +5 to -10 mV. When the papermaking process involves an acid papermaking system, ie, pH of less than about 6.5, the combination of cationic starch phosphate / anionic starch will have a zeta potential of about +20 to +1 mV and preference approximately from +17 to +5 mV. The ratio or index of the components of cationic starch and starch phosphate in the starch combination of this invention can vary to a large extent with the proviso that the range of zeta potential, as described herein, is satisfied. More particularly, the cationic starch phosphate polymer and starch components are generally provided in amounts of about 4: 1 to 1: 4 parts by weight of the cationic starch to the starch phosphate. The term zeta potential (as used herein refers to the electrokinetic potential, the potential through the interface of solids and liquids and more particularly to the potential that crosses the diffuse layer of ions surrounding a colloidal charge particle. zeta refers to surface loading and electrophoretic mobility and is a well-known appropriate measurement.A detailed discussion of zeta potential can be found in "Zeta Potential in Colloid Science, Principles and Applications" by Robert J. Hunter, Academic Press, 1988. Several methods are known to determine the zeta potential of different materials, with electrophoresis being the most common Electrokinetic phenomena are observed when two phases move relative to each other under the influence of an electric field Electrophoresis describes the movement of particles charged or droplets in an applied electric field.A thin layer of liquid adheres to the particle or surface of the droplet so that the cutting plane is located on either side of the liquid. The potential in the plane of cut is called electrokinetic potential or zeta. The zeta potential can be easily measured by the microelectrophoresis technique. This involves measuring the velocity of individual particles in suspension, viewed in a microscope fitted with a grid, the time of transition through the grid that is recorded. Various microelectrophoresis instruments are available to measure the zeta potential. In this application, a Zetasizer 2000 instrument provided by Malvern Instruments Limited is used to measure the zeta potential. The combination of cationic starch and starch phosphate can be effectively used to add pulp prepared from any type of cellulosic fiber, synthetic fibers or combinations thereof. Among the cellulosic materials that can be used are bleached and unbleached sulphate (kraft), bleached and unbleached sulphite, bleached and unbleached soda, neutral sulfite, semi-chemical, chemisorbed wood, defibrated wood or any combination of these fibers.

The viscose rayon fibers or regenerated cellulose type can also be used if desired. Any desired inert mineral filler can be added to the pulp that is modified with the improved starch derivatives of this invention. Such materials include clay, titanium dioxide, talcum, calcium carbonate, calcium sulfate and diatomaceous earths. Other additives commonly introduced in the paper can be added to the pulp or raw materials, for example inks, pigments, size additives, alum, anionic retention aids, etc. The amount of the combination of cationic starch polymer and starch phosphate (ie the total amount of the components of cationic starch and starch phosphate) that can be added to the wet part or paper pulp will be an effective additive amount, especially effective to improve the filling stop. More particularly, from about 0.05 to 10% of the combination of starch and preferably from about 0.1 to 2% by weight, based on the dry weight of pulp or raw materials, can be used. The starch combinations are made as a component, that is, the cationic starch or the starch phosphate is combined as a component to form the starch polymer combination. These starch or combination materials can be added to the papermaking system in the cooked or non-cooked condition. If cooked, ie dispersed or solubilized this can be achieved by standard or known techniques such as batch cooking, jet cooking or steam injection cooking. The starch components may be either cooked together as a mixture or cooked separately, then mixed and combined together and added as a component to the papermaking system. When the starch materials are cooked, the desired paper characteristics can be achieved by using smaller amounts of starch. In addition to the selected starch derivatives and other components that can be included in the alkaline papermaking system as described above, the inorganic colloidal minerals can be added to the system to form an alkaline microparticle system. Such microparticle systems can include colloidal silica or ventonite, and alum and can be incorporated into the system in amounts of less than 0.001% and more particularly from about 0.01 to 1% by weight based on the weight of the dried pulp. Further description of such inorganic microparticle materials can be found in U.S. Patent No. 4,388,150 issued June 14, 1983; U.S. Patent No. 4,643,801 issued February 17, 1987; U.S. Patent No. 4,753,710 issued June 28, 1988 and U.S. Patent No. 4,913,775 issued April 3, 1990; all of which are incorporated herein by reference. The following examples will further illustrate the embodiments of this invention. In these examples all parts are given by weight and all temperatures in degrees centigrade unless otherwise stated. EXAMPLE 1 A cationic starch was prepared in the following manner. Waxy corn (2500 g, approximately 10% moisture) and 3750 mL of water were loaded into a reactor vessel equipped with means for heating and mechanical agitation. Under stirring, the pulp temperature was raised to 43 ° C and the pH was adjusted from 11.2 to 11.5 using an aqueous solution of sodium hydroxide (4% by weight). 208 g of 60% active aqueous solution of 3-chloro-2-hydroxypropyltrimethyl ammonium chloride were added with stirring and the mixture was allowed to react at 43 ° C for 24 hours. The final pH of the system was 11.6. After the reaction was completed, the paste was neutralized to pH 7.0 with 10% hydrochloric acid and vacuum filtered over a Buchner funnel. The cake was washed with water and with dry air at room temperature. It was found to have a nitrogen content of 0.325 by weight on a dry basis (db).

An anionic starch phosphate was prepared as follows. Waxy corn (400 g) with pH adjusted to 8.5 was placed in a Hobart mixer and impregnated with an aqueous solution of sodium tripolyphosphate (STP) (9.5 g STP, 25.8 g H20) to provide a level of 2.3% treatment. The pH of the aqueous STP solution was adjusted to 5.3 with the slow addition of HCl to achieve complete dissolution before starch application. The STP solution was applied to the starch by a manual spray bottle for approximately 5 minutes. After the addition of STP was completed, the mixture was continued for 10 minutes. The resulting impregnated starch was dried at 60 ° C to 4% moisture in an air forced oven. The resulting material was ground to a fine powder, spread as a thin layer on a tray (3-20 mm), and heated at 155 ° for 30 minutes in an air-forced oven. The amount of phosphorus bound in the product was determined by washing the sample with 5% of an aqueous solution of ethylenediamine tetraacetic acid (EDTA) followed by rinsing of distilled water and measuring the phosphorus by inductively coupled plasma (ICP) after the acid solution of the starch. The sample produced was found to have a bound phosphorus content of 0.19%. Similar products were made using tapioca and corn starches. Various combinations of the prepared cationic starch and the starch phosphate were made having different charges of zeta potential (mV). The zeta potentials were determined using a Zetasizer 2000 instrument obtained from Malvern Instruments Limited. Using this instrument, which involves a microelectrophoresis technique, and the procedure recommended by the manufacturer, zeta potential measurements were made for the various combinations. Combinations of the samples were prepared by dispersing 1 g of the selected starch combination in distilled water in a Pyrex 150 mL beaker. The dispersed combination was cooked in boiling water for 30 minutes, with stirring for the first 5 minutes. The combination was diluted to 0.1% with distilled water and cooled to room temperature. Samples of the combination starch solutions (20 mL) were injected into the instrument set at 25 ° C and the average of three zeta potential readings were recorded. The various combinations were evaluated for retention of the filler in alkaline systems and acid paper manufacturing using Standard Dynamic Alkaline Retention Evaluation, Tappi T 261 pm 90. The raw material was prepared to manufacture standard paper using a pulp pulp that It comprises an aqueous pulp of bleached hardwood kraft pulp (BHWK). And bleached soft wood kraft pulp (BSWK).

Pulp pulp (80:20 BHWK: BSWK, parts by weight) was refined in a standard laboratory Valley mill at approximately 400 CSF (Canadian Standard Freeness) and a pH of 7.8 to 8.2 and contained calcium carbonate filler precipitate (30% db) with 8 to 10% of fiber fines and total fines of 37 to 42%. The test was run while mixing and stirring using a bottle of Britt with a sieve having holes of 76 microns in diameter. The combinations of the sample in various proportions with the different zeta potentials were evaluated by adding the selected amounts of the pulp pulp combinations. The percentage of CaCO3 retention was determined for each sample with the results given below in Table 1. Similar results were obtained using an acid papermaking system with the retention clay filler results also given in Table 1 A review of this table and retention results will indicate that appropriate improvements in significant retention are obtained when combinations of cationic starch and starch phosphate having zeta potential values are used with the range selected as described in this application.

TABLE 1 Manufacture of Acid Paper H-6.0) -Percentage of Clay Retention (%) Combinations of Zeta Potential Applied Quantities cationic starch / (mV) (% by weight of raw material) anionic (w / w) 0.5 1.0 1.5 2.0 100/0 +24.5 24.5 24.6 23.4 24.7 80/20 +21.1 28.6 31.5 32.3 33.7 70/30 +17.6 30.9 37.5 40.4 41.7 60/40 +15.8 30.2 38.1 45.6 49.7 50/50 13.3 27.1 38.2 44 52.9 40/60 +1.1 19.4 22.8 27.9 34.6 30/70 -7.8 19.4 24.4 27.9 36.8 20/80 -16.4 18.9 20.9 25.3 28.8 0/100 -19.7 17.2 16.8 16.9 17.0 Alkaline paper manufacture (pH-7.8) - Retention percentage of CaCO3 Combinations of Zeta Potential Applied Quantities cationic starch / (mV) (% by weight of raw material) anionic (w / w) 0.5 1.0 1.5 2.0 100/0 +24.5 11.3 8.2 8.4 8.5 80/20 +21.1 17.2 17.1 16.1 15.9 70/30 +17.6 19.4 19.7 19.4 18.7 60/40 +15.8 20.2 21.6 20.9 20 50/50 13.3 23.2 25.2 26.3 26.5 40/60 +1.1 27.2 32.1 32.2 33 30/70 -7.8 23.7 26.6 27.5 29.4 20/80 -16.4 20.9 22.9 24.1 26.2 0/100 -19.7 18.4 18.4 18.8 17.2 EXAMPLE 2 For comparative purposes, combinations of the sample of cationic starch and starch phosphate as prepared in Example 1 and having the zeta potential within the preferred ranges were evaluated for calcium carbonate retention and compared with an amphoteric waxy starch material (0.25% cationic N content, 0.12% P-bound content). ) and a cationic waxy starch (0.36% N quaternary). The results are reported in Table 2 below. Similar results are given for the same combinations of starch in an acid system to determine the percentage of retention of filler clay. The results are also found in Table 2. The results show the significantly improved retention properties in acid and alkaline paper manufacturing systems when the starch combinations of this invention are used when compared to an amphoteric starch (which has both groups). cationic as anionic in the same starch molecule) or cationic starch.

TABLE 2 Alkaline Paper Manufacturing System Amount Applied (% by weight of Raw Material) Samples Potential zeta (mV) 0.5 1.0 1.5 2.0 Combination of 50/50 of +13.3 17.1 18.8 19.6 18.3 Cationic / anionic starch Combination of 40/60 of +1.1 20.6 20.8 21.5 22.5 Cationic / anionic starch Control (amphoteric starch) +14.8 12.6 11.1 10.4 9.2 Control (cationic starch) 24.5 9.2 6.3 5 5.6 Acid Paper Manufacturing System Quantity Applied (Weight% of Raw Material) Samples Potential zeta (mV) 0.5 1.0 1.5 2.0 Combination of 50/50 of +13.3 44.1 49.3 50.1 47.6 cationic / anionic starch Combination of 40/60 of +1.1 44.6 49.5 48.8 47.6 Cationic / anionic starch Control (amphoteric starch) +14.8 35.6 36.7 35 33.3 Control (cationic starch) +24.5 27.4 25.6 24.7 26.5 EXAMPLE 3 Additional combinations of cationic starch and starch phosphates were prepared as in Example 1 using tapioca starch as the base material. The cationic tapioca had a nitrogen content of 0.24% (db) and tapioca phosphate had a bound phosphorus of 0.18%.

Combinations of the tapioca starches were made by having the zeta potentials within the desired range and were evaluated for calcium carbonate retention in an alkaline papermaking system and for the retention of clay in an acid papermaking system. The results are shown in Table 3 below and compared with an amphoteric tapioca starch (0.28% cationic N, 0.1% bound P) and a cationic tapioca starch (0.24% cationic N). The results in Table 3 show the significant improvement in retention in the acid and alkaline papermaking systems when the starch combinations of this invention are used when compared to the amphoteric tapioca (which has cationic and phosphate groups therein). starch molecule) or a cationic tapioca starch.TABLE 3 Preparation of Acid Paper (pH 6.0) -Retention of Clay (%) Amount Applied (% by weight of Raw Material) Samples Potential zeta (mV) 0.5 1.0 1.5 2.0 Tapioca Caiónica Aniónioca +13.8 48.5 54.7 56.9 56.6 (Combination p / p-50/50) Cationic Tapioca / Aniónioca -4.9 46.4 56.5 6.3 63.9 (Combination p / p-40/60) Amphoteric tapioca (Control) +22.5 34.2 33.7 32.3 32.2 Amphoteric tapioca (control) +28.7 28.6 28.6 30.4 29.6 Alkaline Paper Manufacturing (pH 7.8) -CaCO3 Retention (%) Amount Applied (% by weight of Raw Material) Samples Potential zeta (mV) 0.5 1.0 1.5 2.0 Tapioca Cationic / Anionic +13.8 21.1 21.5 21.4 20.8 (Combination p / p-50/50) Cationic Tapioca / Aniónioca -4.9 22 22.2 24.3 23.8 (Combination p / p-40/60) Amphoteric tapioca (Control) +22.5 14.7 13.3 11.6 11.6 Cationic tapioca (Control) +28.7 10.4 8.3 8.4 9.6 EXAMPLE 4 Samples of cationic starch and starch phosphate were prepared as in Example 1 with the individual starches separately boiled and then combined together before being added to the papermaking system.

The combinations of starch were evaluated as a sample of 50/50 weight / weight (w / w) for the retention of CaC03 in an alkaline papermaking system. The results are compared with an amphoteric starch and a cationic starch (all starches are the same as in Example 1) and given below in Table 4. These results show the improved retention properties for the starch combinations of this invention when compared with amphoteric or cationic starches. TABLE 4 Alkaline Paper Manufacturing (pH 7.8) - Retention of CaCO3 (%) Applied Quantity (% by weight of Raw Material) Samples Potential zeta (mV) 0.5 1.0 1.5 2.0 Cationic Phosphate / Starch 15.3 23.4 26.9 28.1 32.4 (Combination 50/50-p / p) Amphoteric Starch (Control) 13.7 23.5 22.8 20.3 20.3 Cationic Starch (Control) 25.3 17.5 14.8 10.8 12.8 EXAMPLE 5 The waxy maize starch was impregnated with an aqueous sodium tripolyphosphate solution in accordance with a method described in U.S. Patent 4,166,173. After impregnation, the total amount of phosphorus in starch was 1.05% by weight. Four (4) kg of the impregnated starch was then dried in a fluidized bed reactor by heating to approximately 113 ° C (235 ° F) until the moisture content was less than about 1% by weight. In order to effect phosphorylation, the dry impregnated starch in the reactor was heated and reacted at a temperature of about 116 ° C (240 ° F) for 45 minutes. The heat treatment in the fluidized bed reactor resulted in a bound phosphorus level of 0.17%. The waxy maize starch phosphate ester, prepared as described above, was mixed with a cationic waxy corn starch, prepared as in Example 1, at a rate that resulted in a zeta potential of +14.5 mV, ( Sample A). This Sample A together with a reference sample (Sample B) which is a mixture of cationic starch and anionic starch in a weight ratio of 50:50 and made as described in Example 1, were evaluated for drainage performance in the pulp of paper under acidic conditions. The results are shown below in Table 5.

TABLE 5 Drain Performance of the Acid Paper Manufacturing (pH - 6.0) Addition of Starch Sample A Sample B Ibs / T Drain (cc / seq.) Drain (cc / sec) 10 128 124 20 165 158 30 187 176 40 200 186 The results in Table 5 show that the drainage performance of the The mixture containing the fluid bed made from the dry starch phosphate at anhydrous conditions (Sample A) was better than the reference mixture (Sample B) which contained the starch phosphate prepared in the conventional manner. The mixture of cationic waxy maize starch and waxy maize phosphate prepared using anhydrous conditions and a fluidized bed reactor, such as described in the above (Sample A) was evaluated for retention of fill. This was achieved in an alkaline papermaking system as described in Example 1. The results were compared with a reference sample made from a mixture of cationic starch and anionic starch (made in a conventional manner) (sample B) and made according to Example 1. The results shown below in Table 6 indicate that the retention performance of Sample A (fluidized bed / anhydrous starch phosphate) was significantly increased when the level of addition of starch was increased to 40%. lbs / ton of paper and was similar to that of the reference sample. TABLE 6 Retention Yield Alkali Paper Production (pH-7.8) Addition of Starch Sample A Sample B Ibs / T Retention (% CaCO) (Retention (% CaCQ) 16.5 20.3 20 30.5 36.5 30 42.3 45.1 40 49.2 49.6 EXAMPLE 6 A potato starch phosphate ester was prepared in a fluidized bed reactor as follows. It was dissolved in sodium tripolyphosphate (188 g) in 6000 g of water. Then 4000 g was drained. of dry weight, of the potato starch in the solution of aqueous sodium tripolyphosphate. The pulp was stirred for 30 minutes and filtered on a Buchner funnel. The resulting starch cake was dried with air at a moisture content of approximately 12% by weight and defibrated using a Prater mill. The phosphorylation reaction in a fluidized bed reactor was carried out as follows. The starch was dried in the fluidized bed reactor at a temperature of about 110 ° C (230 ° F) until the moisture content of the starch was less than 1%. Then, the temperature was increased to the reaction temperature of 149 ° C (300 ° F) and maintained for 30 minutes. The reaction resulted in a potato starch phosphate ester having 0. 24% bound phosphorus. The potato starch phosphate ester was mixed with a cationic waxy corn starch (prepared as described in Example 1) in a proportion that resulted in a zeta potential of +14.0 mV (Sample D). Sample D and Reference Sample B (prepared as described in Example 5) were evaluated for drainage performance in the pulp of paper under acidic conditions. The results shown below in Table 7 indicate that the mixture containing the fluidized bed / potato starch phosphate prepared anhydrous (Sample D) showed an increased drainage rate as the level of starch addition increased to 40 lbs / ton of paper. Also Sample D showed drainage significantly faster than Reference Sample B. TABLE 7 Drainage Performance Acid Papermaking (pH-6.0) Addition of Starch Sample D Sample B Ibs / t Drain (cc / seq.) Drain (cc / seq.) 10 147 143 20 195 167 30 234 181 40 250 192 The mixture of potato starch phosphate ester and the cationic waxy corn starch (Sample D) described above was evaluated together with Reference Sample B for retention of the filler in an alkaline manufacturing system (as described in Example 1). The results given in Table 8 show an increased level of filler retention for the sample mixture containing the potato starch phosphate ester (Sample D) as the level of starch addition increased to 40 lbs / ton. of paper. The retention of the fill of Sample D was also significantly better than that of Reference Sample B. TABLE 8 Retention Performance Alkali Paper Production (pH-7.8) Starch Addition Sample D Sample B Ibs / t Retention (% CaCO3) Retention (% CaCO3) 44.9 15.9 20 69.1 28.9 30 68.7 40 40 62.2 47.6 EXAMPLE 7 A waxy maize starch phosphate ester was prepared as follows. Sodium tripolyphosphate (88 g) was dissolved in 4500 g of water, then the waxy corn starch (3000 g dry weight) was drained into the aqueous sodium tripolyphosphate solution and stirred for about 10 minutes. The starch paste was filtered on a Buchner funnel then air dried and defiberized using a Prater mill. The starch was then dried in a fluidized bed reactor by heating at 116 ° C (240 ° C) until the moisture content was less than 1%. The temperature of the fluidized bed reactor was then increased to 149 ° C (300 ° F) and held there for 60 minutes to phosphorylate the starch. This reaction resulted in a bound phosphorus of 0.19%. The waxy maize starch phosphate was mixed with cationic corn starch (described in Example 1) in a proportion that resulted in a zeta potential of +12.5 mV (Sample E). Sample E was evaluated for drainage performance in paper pulp under acidic conditions. The results were compared with the drainage performance of Sample A (Example 5). Sample A contains a waxy maize starch phosphate ester which was made in a fluidized bed reactor at a significantly lower reaction temperature (116 ° C / 240 ° F). The results shown below in Table 9 indicate that Sample A has better drainage performance than Sample E. This is an indication that the use of phosphorylated starch prepared in a fluidized bed reactor at high temperature and time conditions ( Sample E) has a negative effect on the performance of the starch phosphates as a drainage aid in papermaking (compared to Sample A). TABLE 9 Drainage Performance Acid Papermaking (pH 6.0) Addition of Starch Sample E Sample A Ibs / t Drain (cc / seq.) Drain (cc / seq.) 10 76 128 20 96 165 30 113 187 40 135 200

Claims (17)

1. CLAIMS 1. A method for making paper having improved retention properties characterized in that it comprises adding to the pulp before or during the formation of the sheet, an effective amount of a combination of more than one starch polymer comprised of a cationic starch and a starch phosphate, the starch polymer combination is provided to have a zeta potential of about +20 to -18 mV.
2. 2. The method of compliance with the claim 1, characterized in that the starch in the components of cationic starch and starch phosphate is waxy corn, corn, tapioca, potato starch or a combination thereof.
3. 3. The method according to claims 1-2, characterized in that the cationic starch is cationized with a tertiary amino or quaternary ammonium ether group.
4. 4. The method according to claims 1-3, characterized in that the starch phosphate is prepared by the reaction with an ortho-, pyro-, meta- or tripolyphosphate of alkali metal.
5. 5. The method according to claims 1-4, characterized in that the cationic starch has a cationic ether group of 2-diethylaminoethylchloride or 3-chloro-2-hydroxypropyltrimethyl ammonium.
6. 6. The method according to claims 1-5, characterized in that the starch phosphate is prepared by the reaction with alkali metal tripolyphosphate.
7. The method according to claims 1-6, characterized in that the paper is made in an alkaline papermaking system and the zeta potential of the starch combination is about +18 to -18 mV.
8. 8. The method according to claim 7, characterized in that the zeta potential of the starch combination is +15 to -10 mV.
9. 9. The method according to claims 1-6, characterized in that the paper is made in an acid papermaking system and the zeta potential of the starch combination is from about +20 to +1 mV.
10. 10. The method according to claim 9, characterized in that the zeta potential of the combination of starch is from +17 to +5 mV.
11. 11. The method according to claims 1-4, characterized in that the zeta potential of the starch combination is from about +15 to about -5 mV.
12. 12. A paper containing homogeneously dispersed therein a combination of cationic starch and starch phosphate, the combination of starch is characterized in that it has a zeta potential of +20 to -18 mV.
13. 13. The paper in accordance with the claim 12, characterized in that the starch in the components of cationic starch and starch phosphate is waxy corn, corn, tapioca, potato starch or a combination thereof and the cationic starch is cationized with a tertiary amino or quaternary ammonium ether group .
14. 14. The paper made by the method according to claims 1-11.
15. 15. The method according to claims 1-11, characterized in that the starch phosphate is made by a) impregnating the starch with a phosphate reagent to form an impregnated starch: b) drying the impregnated starch at substantially anhydrous conditions; and c) heating to phosphorylate the starch.
16. The method according to claim 15, characterized in that the impregnated starch is dried at a moisture content of less than 1% by weight of the starch.
17. 17. The method according to claims 15-16, characterized in that the impregnated starch is dried and phosphorylated while in a fluidized state.