Method for producing extruded starch and paper

Abstract

The method of making paper includes the steps of providing a stock comprising fibrous material, extruded starch, and optionally inorganic fillers. The stock is pressed to a minimum solids content before drying. The extruded starch may be a) cationic starch, b) chemically or enzymatically modified, c) non-crosslinked starch, d) 40-99% solubility, e) molecular weight greater than 300,000 Da, f) weight fraction greater than 30,000,000 Da and less than or equal to 0.05, and / or g) RVA viscosity less than or equal to 15,000 cP. The input starch is extruded with water. Optionally, one or more of a polyol, a wetting agent, or a plasticizer may be added. Optionally, the starch may be modified during extrusion with chemical agents or enzymes. Optionally, the extrusion is substantially free of crosslinking agents.

Description

[Technical field]

[0001] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 329,114 (titled "Production of Paper and Board"; filed April 8, 2022) and No. 63 / 351,149 (titled "Extruded Starch and Process of Producing Paper"; filed June 10, 2022), the contents of both documents being incorporated herein by reference. [Background technology]

[0002] The present invention relates to paper (including tissue, toweling, card and board) and methods of making paper, to starch derived materials and the use of starch derived materials in the manufacture of paper, for example as dry strength agents.

[0003] The following description is in no way an admission that the matter described herein is prior art or within the common general knowledge of those skilled in the art.

[0004] Papermaking is a substantially continuous process on a papermaking machine. Many modern papermaking machines are derived from older machines, such as the Fourdrinier machine developed in the early 1800s. A typical Fourdrinier machine includes at least a forming section, a press section, and a drying section. Stock is made by combining fibers (alternatively called "fiber stock") with other materials such as fillers, optionally using refining or other physical or chemical treatments, and the stock is transferred to the head tank (alternatively called "headbox" or "stock box") of the papermaking machine. From the head tank, the stock is transferred to the headbox of the papermaking machine, from where it is transferred to a wire (typically a moving fabric loop) in the forming section. Water is drained from the stock through the wire, often assisted by suction, to produce a coherent sheet, optionally referred to as a "web." The sheet is delivered to a press section where further water is removed by pressing the sheet against a felt which absorbs the water. The pressed sheet is then delivered to a dryer section where it is dried by passing through a series of thermally, e.g. steam heated, cylinders. In some cases, these sections are followed by one or more of a size press, a calendar section and a coating section. A reel section at the end of the paper machine winds the paper onto rolls for storage, transport or further processing. Alternatively, other paper machines, e.g. cylinder mould paper machines or tissue machines, may perform similar steps to the paper machine described above, using different arrangements and designs of the sections of the paper machine. Paper may be produced in a wide variety of thicknesses (i.e. 0.07-0.18 mm, etc.) and weights (e.g. 15-300 g / m2). 2 Or 30~300g / m 2 ) and can be made of ordinary multipurpose paper or printing paper (optional 60~120g / m 2 range) to card (optional 130g / m 2or more) or paperboard (optionally 250 g / m 2 and above), and can be formed in single or multiple layers and with a variety of surface properties and other attributes.

[0005] In some cases, starch is added to the stock, for example as a dry strength agent. In conventional processes, native starch granules are heated in water to form a starch solution immediately prior to use at the papermaking site. Dissolution of the starch granules is most typically accomplished by a jet cooking process in which the aqueous starch slurry is contacted with steam at a temperature of about 120-130°C, with dissolution occurring in a tube for a processing time of about 1-2 minutes. After dissolution of the starch is complete, it is typically diluted to less than 1% solids content before being added to the papermaking stock to ensure homogeneous mixing with the stock. The dissolved starch is used promptly after production to avoid microbial spoilage or aging.

[0006] In another example, a pregelatinized starch slurry or dry cold water soluble starch is mixed with water and added to the papermaking stock. Cold water soluble starch can be made, for example, by the method described in U.S. Pat. No. 5,037,929. Alternatively, Tate & Lyle's STA-LOK™ contains pretreated cationic waxy corn starch, which is provided as a 30% solids slurry. In another example, regenerated starch particles can be used, for example, as described in EP-A-1,176,254. Summary of the Invention

[0007] The following introduction is intended to introduce the present disclosure to the reader, but does not identify any invention. One or more inventions may be included in any combination or subcombination of the features described below, or elsewhere in this specification. The inventors in this specification in no way waive or abandon their rights to any inventions not disclosed herein simply because they do not recite other inventions in the claims.

[0008] This specification describes a method for making paper. The method comprises the steps of providing a paper stock, optionally called stock for short, comprising a fibrous material such as a fibrous stock, moisture, optionally one or more inorganic fillers, and extruded starch. Optionally, the stock may comprise one or more additives or adjuvants. A web is formed from the stock. The web is pressed and dried to at least a minimum solids content. The minimum solids content is 46+(x-10)x0.3 (wt%), where x is the ash content of the dried paper. The extruded starch optionally has one or more attributes. In some examples, the extruded starch is a cationic starch. In some examples, the starch is chemically or enzymatically modified in the extruder, for example to thin the starch. In some examples, the extruded starch is not a crosslinked starch. In some examples, the solubility of the extruded starch is in the range of 40-99%, or 40-93%, or 40-92%, or less than 92%, for example, as determined by the amount of Rapid Soluble Starch (RSS). In some examples, the molecular weight of the extruded starch is greater than 300,000 Da. In some examples, the weight fraction of the extruded starch is greater than 30,000,000 Da and is 0.05 or less. In some examples, the RVA viscosity of the extruded starch at 20% S (solids content) is 15,000 cP or less.

[0009] The present application also describes compositions comprising extruded starch. In some embodiments, the extruded starch is a cationic starch. In some embodiments, the extruded starch is not a cross-linked starch. In some embodiments, the solubility of the extruded starch is 40-99% or 40-93%. In some embodiments, the molecular weight of the extruded starch is 300,000 Da or more, 500,000 Da or more, 2,000,000 Da or more, or 4,000,000 Da or more. In some embodiments, the weight fraction of the extruded starch is greater than 30,000,000 Da and less than 0.05. In some embodiments, the RVA viscosity of the extruded starch at 20% S (solids content) is 15,000 cP or less, or 5,000 cP or less.

[0010] The present application further describes a method of making a composition comprising extruded starch. The input starch or starch-containing material is extruded with water. Optionally, one or more of processing aids, polyols, humectants, or plasticizers (i.e., glycerol) can be added during or after extrusion. Optionally, the starch is acid thinned or enzymatically modified after or during extrusion. Extrusion can be performed in a twin-screw extruder, optionally with one or more mixing and / or high shear sections. Optionally, the input starch can be a cationic starch or the starch can be cationized in the extruder.

[0011] In at least some instances, the above-described extruded starches and / or methods of making paper using extruded starches result in a final paper that has increased dry strength compared to papers made using conventional starches. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a graphical representation of the dependence of Short Span Compression Test (SCT) results on cationic charge level for selected pressed sheets including starch sample blanks 1, 15, and 16 at 5 kg / t and 10 kg / t. [Diagram 2]FIG. 1 is a graphical representation of the dependence of short span compression test (SCT) results on molecular weight for selected pressed sheets containing starch samples 1, 10, and 11 at 5 kg / t and 10 kg / t. [Diagram 3] FIG. 1 is a graphical representation of the dependence of short span compression test (SCT) results on cross-linking for selected pressed sheets containing starch samples 1, 3, 12, 13 at 5 kg / t and 10 kg / t. [Figure 4] FIG. 1 graphically illustrates the dependence of burst test results on cross-linking for selected pressed sheets containing starch samples 1, 3, 12, 13 at 5 kg / t and 10 kg / t. [Diagram 5] FIG. 1 is a graphical representation of the dependence of short span compression test (SCT) results on dry solids content (low DC, high DC) for selected pressed sheets containing starch samples 1, 17, and 18 at 5 kg / t and 10 kg / t. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] In this specification and claims, the singular forms "a," "an," and "the" include the plural forms unless the context clearly indicates otherwise.

[0014] In a method of making paper, starch is added to the stock, for example upstream of or at the wet end. The starch is optionally added together with or after the addition of fillers or additives. In some cases, the starch is added to the fibrous material before other additives or fillers are added. The starch can be added to the thick or thin stock. The addition of starch increases the strength of the final paper product. The starch can be, for example, regenerated starch particles, which have been regenerated such that the crystalline structure of the native starch granules is broken down to form a new particle structure. Each starch particle contains a number of starch molecules, which can optionally be cross-linked to one another. For example, the starch particles can be produced as described in EP 1,176,254, the contents of which are incorporated herein by reference. In another example, the starch is a thermomechanically processed starch, in which the crystalline structure of the native starch granules is broken, but new supramolecular structures are not necessarily formed, or alternative starch molecules may coexist with the supramolecular starch structure. Starch particles or other forms of thermomechanically processed starch can be produced in an extruder, and when referring to simply "extruded starch", the term may refer to these forms of starch. However, other methods can be used to produce similar materials. For example, high shear static mixers can be used, which generate a similar amount of mechanical energy. In contrast, some extruders generate less mechanical energy and rely more on heat to substantially heat the starch, and such starches do not result in the same material. Extruders that generate a large amount of mechanical energy include, for example, twin-screw co-rotating extruders.

[0015] In some cases, the extruded starch is not entirely soluble, but the insoluble structures may be very small, e.g., in the range of 10-1000 nm or 50-500 nm, and may behave similarly to a solution, although its mechanical behavior is more accurately described as a "dispersion". In some cases, the mixture of extruded starch in water may contain some dissolved starch molecules and some more dispersed starch molecules, supramolecular structures or particles. The terms "dispersion" and "solution" are used herein to refer to the mixture of extruded starch in water, but are not used in accordance with their strict technical definition.

[0016] In some examples, the extruded starch contains 99% or less, or 93% or less, or 92% or less rapidly soluble starch (RSS). Rapidly soluble starch is a starch that behaves as if it is in solution to some degree when mixed with room temperature water, whether or not it is truly soluble. RSS is measured by adding 4 g of dry extruded starch to 200 ml of deionized water, stirring at 600 RPM for 2 minutes, centrifuging at 3000 RPM for 15 minutes, decanting or pipetting off 100 ml of the supernatant, drying the supernatant in an oven at 110°C, and measuring the remaining dry mass, which represents the mass of starch in the supernatant. The dry mass is divided into 2 g portions and converted to a percentage to determine the RSS. In the example detailed below, without chemical or enzymatic modification of the starch, the RSS obtained with a twin screw extruder was 92%. In another example, starch containing 97% RSS was chemically modified with acid in an extruder. The amount of acid used was less than that used to produce acid-thinned starch outside the extruder. It is expected that enzymatic treatment in the extruder could be used alternatively or additionally to produce starch with up to 97% or 99% RSS. Crosslinked starches produced in an extruder tend to contain much less RSS. However, optionally an RSS of 40 or more can be achieved by crosslinking.

[0017] As explained in more detail below, the addition of extruded starch to the stock provides the finished paper with improved strength or other mechanical properties compared to paper made with conventional cooked starch. The mechanical or other properties can be further improved by selecting an extruded starch with one or more optional properties. For example, the extruded starch is optionally not a crosslinked starch. The extruded starch optionally has an RSS in the range of 40-97% or 40-93%. Optionally, the extruded starch has a molecular weight of 300,000 Da or more, 500,000 Da or more, 2,000,000 Da or more, 4,000,000 Da or more, or 5,000,000 Da or more. Optionally, the extruded starch has a weight fraction of more than 30,000,000 Da but less than 0.05. Optionally, the extruded starch has an RVA viscosity at 20% solids of not more than 15,000 cP, or not more than 10,000 cP, or not more than 5,000 cP. Optionally, the extruded starch is a cationic starch. Optionally, cationicity is measured as the percentage of nitrogen bound to the starch excluding protein nitrogen, which is about It can be in the range of 0.1 to 1.6% or 0.1 to 0.8%.

[0018] Other steps in the papermaking process can be performed to further improve the mechanical properties. Further in the papermaking process, the web or sheet formed from the stock is pressed. In Fourdrinier papermaking machines, the web is transferred from the forming section to a separate press section. In other papermaking machines, web forming and pressing can be at least partially integrated, or other configurations of similar machines can be used. The web comprises fibrous material and extruded starch, optionally one or more mineral fillers, and optionally one or more other additives. Typically, the web after pressing is further dried in a thermal drying process.

[0019] The inventors have determined that pressing or otherwise dewatering the web to at least a minimum solids content improves the strength and other mechanical properties of the final paper, especially when the web contains extruded starch. The minimum solids content may also vary depending on the amount of inorganic filler present in the web. In some instances, the stock is pressed to a minimum solids content determined by the following formula (I): D(x)=46+(x-10)×0.3 (I)

[0020] where D(x) is the minimum solids content in weight percent and (x) is the ash content in weight percent of the final paper. The minimum solids content refers to the solids content of the pressed sheet and can be determined using the oven drying method of ISO 638:2008. The ash content x can be measured according to ISO 1762:2019. The ash content of the final paper is related to the amount of inorganic fillers added to the paper stock.

[0021] In some examples, extruded starch is made by adding one or more starch-containing input materials, such as native starch or flour, to an extruder. Water is also added to the extruder. Optionally, a processing aid, polyol, humectant, or plasticizer (such as glycerol) can be added to the extruder. When a processing aid, polyol, humectant, or plasticizer is added to the extruder, it can be added upstream or downstream of the machining area where the majority of the machining of the input material occurs. In another option, a processing aid, polyol, humectant, or plasticizer, if added, can be added to the extrudate after extrusion. The one or more starch-containing input materials suitably constitute 80% or more of the solids (i.e., all materials other than water) added to the extruder.

[0022] The starch can be treated with mechanical energy. Mechanical energy can be supplied to the starch using a high shear mixer, under some conditions a single screw extruder can be used, or a twin screw extruder can be used, which can be equipped with co-rotating or counter-rotating screws. A suitable extruder has two co-rotating screws. The extruder can have multiple barrels, in particular 5 or more or 7 or more barrels. The extruder preferably has one or more mixing and / or high shear sections. The mixing and / or high shear sections can have reverse kneading elements or can have forward and reverse kneading elements. The extruder or other high shear mixer can apply a specific mechanical energy of 100 Wh or more, or 150 Wh or more, per kg of starch-containing input material. The extruder preferably operates at a temperature below 180° C. to reduce or avoid the inclusion of short chain molecules (DP<6) in the extruded product. The maximum barrel temperature of the extruder (the temperature in the hottest barrel) can be less than 180° C. or less than 160° C., or can be in the range of 120 to 160° C. The extruder can be one of those described in U.S. Pat. No. 9,011,741 (titled Process for Producing Biopolymer Nanoparticles), the contents of which are incorporated herein by reference.

[0023] The input material comprises starch. The input material can be only one type of native starch, or it can be flour, or any combination of starches, or a combination of starch and flour. In some cases, the starch is not substantially acid thinned, but a small amount of acid can be added as a processing aid. Optionally, a weak acid (pKa of 1 or greater) can be added at less than 1% or less than 0.5% by weight of the input material on a solids basis, if added. Optionally, a strong acid can be added at less than 0.7%, less than 0.5%, or less than 0.0001% by weight of the input material on a solids basis, if added. Optionally, one or more enzymes, if added, can be added at less than 10% solids of the input material. The molecular weight of the product may be at least 300,000 Da, at least 500,000 Da, at least 2,000,000 Da, at least 3,000,000, at least 4,000,000 Da, or at least 5,000,000 Da. In some cases, the polydispersity (Mw / Mn) of the extruded product is less than 2. The extruded product is composed primarily, i.e., 80% or more by weight on a dry basis, of starch, protein, or other materials present in native starches or flours, or derivatives thereof.

[0024] Some of the examples of extruded starches mentioned above were compared with commercially available pre-gelatinized starches. Three input materials were used to make novel extruded starch products by the above method. Maximum barrel temperatures ranged from 120-160°C. SMEs ranged from 175-300Wh / kg of starch-containing input material. In sample A, the input material was dent corn starch, in sample B, the input material was corn flour, and in sample C, the input material was waxy corn starch. The extruder was that described in US Pat. No. 9,011,741. The input materials were introduced with glycerol (5% glycerol by weight, 95% starch or flour by weight) and water, but no crosslinker or acid.

[0025] A sample of PCF1000, a commercially available pre-gelatinized corn flour from Bunge, was tested for comparison. This product was made by processing corn flour in a single screw extruder. Although an extruder can be used to make pre-gelatinized starch, single screw extruders are typically configured to output low specific mechanical energy (SME) and provide a thermal process rather than mechanical energy. The extruder is used to provide a plug flow process to heat the starch rather than mechanically process it. The SME of a single screw extruder is typically well below 100Wh / kg. In at least some cases, commercially available pre-gelatinized starch may be processed at very high temperatures, for example at temperatures above 180°C. High temperatures may result in a high amount of short chain molecules being formed.

[0026] Various samples were tested by gel permeation chromatography (GPC) in dimethylsulfoxide (DMSO) to determine the molecular weight and molecular weight distribution of the samples. Gel permeation chromatography was performed on a Malvern Viscotek GPCmax equipped with a Malvern Viscotek TDA (triple detector assembly). The Viscotek TDA was equipped with refractive index (RI), intrinsic viscosity, and light scattering (LALLS, RALLS) detectors. Separation was performed using a Polyanalytik (London, Ontario, Canada) PAA-206M size exclusion chromatography column, which had a measuring dimension of 8 × 300 mm and was packed with a polyhydroxymethacrylate-based gel with an estimated exclusion limit of 2 × 107 g / mol. Calibration was performed with Pullulan 50K (product no. PATD-PUL50K, Mw: 46,001 g / mol, PDI: 1.069) and confirmation was performed with PolyCAL™ Dextran Std-T73K (Mw: 71,747 g / mol, Mn=53,956 g / mol). Both products were obtained from Polyanalytik (London, Ontario, Canada). All samples were analyzed under the following experimental conditions: flow rate 0.6 ml / min, column temperature 70 °C, mobile phase: DMSO (>99.9%) from Anachemia (Montreal, Quebec, Canada) and 0.05 M LiBr (99+%) from Sigma-Aldrich (Oakville, Ontario, Canada), sample concentration 2–3 mg / ml, injection volume 100 μl, and number of replicates 4. The samples were diluted and filtered using a 0.2 micron filter before loading onto the GPC column, and the results are shown in Table 1 below. "% recovery" refers to the percentage of solids in the sample that passed through the 0.2 micron filter. Table 1: GPC analysis of various starch samples [Table 1]

[0027] The molecular weight (MW) graph is 4×10 for all samples. 6 ~6×10 6 However, PCF1000 showed a relatively small peak in this range, with a peak molecular weight of 1×10 6 ~2×10 6 The PCF1000 distribution graph also showed a maximum of 4×10 7 The molecular weight fraction (WF / dLogMW, where WF means weight fraction and dLogMW means the interval of the logarithm of the molecular weight Mw) is 3×10 7 In comparison, the molecular weight fraction of samples A, B, and C was 3 × 10 7 In comparison, commercially available acid-thinned starches typically have a MW of 2×10 6 is less than.

[0028] The viscosity of the samples was tested using a Rapid Visco Analyzer (RVA, Perten Instruments) with the following operating procedure: Sample and analyte solutions were dispensed into a new canister at a concentration of 20% solids. Specifically, 7.0 g of dry product was added into the canister, and analyte was added up to a total mass of 35.0 g. Sample weight was determined by correcting for sample moisture content to obtain a constant dry weight. The canister was loaded with a new paddle, and the sample was pre-homogenized to ensure that all sample lumps attached in the canister were transferred into the water and immediately inserted into the RVA instrument to start the measurement. Analyte solutions were prepared by dissolving 16.0 g of sodium carbonate (Na2CO3) or 18.7 g of sodium carbonate mono-hydrate (Na2CO3·H2O) in 2 kg of demineralized water containing 0.4 ml of Acticide GA biocide (Thor Chemicals). The RVA is designed to measure the viscosity profile of a sample undergoing a thermal cycle, which allows for the solubilization of the product and is accompanied by an increase in the viscosity of the sample. The temperature dependent viscosity behavior is a material property and is measured depending on the temperature program. The following program was used: [Table 2]

[0029] The output of the RVA is a viscosity-time curve. A final viscosity RVA result is recorded for each sample. This output is dependent on many factors including starch type, amylose content, molecular weight, and molecular weight distribution. Results generated using the above sample preparation and RVA analysis protocol are shown below in Table 2. cP is an abbreviation for centipoise, a unit of measurement for viscosity. Table 2: RVA analysis results for various starch samples [Table 3]

[0030] The viscosity of starch dispersions is influenced by the starch's plant-derived components, molecular weight, and other factors. For example, dent starch retrogrades in water to a greater extent than waxy corn starch. Retrogradation is a combination of recrystallization and hydrogen bonding or freezing, and is usually accompanied by a series of physical changes, such as an increase in viscosity and turbidity of the retrograded starch solution. In particular, in the case of non-waxy starches, retrogradation transforms the starch paste into a firm gel consisting of a three-dimensional network structure. Retrogradation may have caused the significantly higher viscosity of sample A compared to sample C. The viscosity of the extruded starch made with waxy corn starch was actually lower than that of the extruded starches made with the other input furnishes.

[0031] To compare samples from similar plants, both PCF1000 and Sample B were made with corn flour. As shown in Table 2, the viscosity of Sample B is much lower than PCF1000, even though both have similar input materials. The inventors believe that the lower viscosity of Sample B is due to the fact that Sample B is an extruded starch as described herein, rather than a traditional pre-gelatinized starch. Without intending to be limited or bound by theory, the narrower MW distribution of Sample B (higher peak in the molecular weight distribution graph, above 1.5 WF / dLogM) than PCF1000 (peak of about 1.3 WF / dLogM) and the larger molecular weight tail of PCF1000, i.e., 3×10 for Sample B, are the causes of the viscosity reduction. 7 and / or the relative absence of molecular weights above 1.0.

[0032] Very high molecular weight starches adhere to the fiber surface, but due to their bulkiness, tend to become detached over time. Very low molecular weight starches do not hold the fibers together and do not impart strength. Suitable molecular weights (meaning weight average molecular weight unless otherwise specified, alternatively referred to as Mw, which is typically near the peak of the WF / dLogMW vs. log Mw graph) can be 2,000,000 Da or more, or 4,000,000 Da or more, and optionally up to 12,000,000 Da, up to 10,000,000 Da, or up to 8,000,000 Da. Jet cookers tend to produce very high molecular weight starches, for example in the range of 27,000,000 Da to 390,000,000 Da for starches produced at 140°C to 110°C, at least some of which may desorb from the pulp fibers during the papermaking process and not contribute to strength. Acid hydrolyzed and oxidized starches produced without an extruder may have lower molecular weights (compared to the low amounts of acid or enzymes used as processing aids in making extruded starches), but random chain scission tends to produce a large fraction of very low molecular weight starches that do not contribute to strength. The extrusion process preferentially destroys starch molecules above a critical molecular weight while minimizing further degradation of starch molecules below the critical molecular weight, which is inversely related to the shear stress (i.e., specific mechanical energy or SME) applied by the extruder. For example, the MW of the cationic starch used in Figure 1C below is about 4,000,000 Da, with 0% weight fraction below 1,000,000 Da, about 10% weight fraction above 10,000,000, and 0% weight fraction above about 25,000,000 Da. The weight fraction below 1,000,000 Da for other extruded starches can range from 0-8% or 0-1%, or below 100,000 Da. Acid hydrolysis, oxidation treatment, and enzyme treatment randomly break starch molecules, resulting in the formation of starch molecules where some have very small molecular weights.Starch that is not attached to the fibers cannot improve paper strength and also increases the biological oxygen demand (BOD) of wastewater produced by the papermaking process.

[0033] Typically, the extruded starch is added to the stock upstream of the paper machine. Alternatively, the extruded starch can be added to the stock in the paper machine, but upstream of the press section or similar section or equipment. The stock can include a mixture of fibrous material, extruded starch, optionally one or more inorganic fillers, optionally paper auxiliaries and other additives, and water.

[0034] In some examples, the stock is prepared by adding extruded starch to an aqueous suspension of fibrous material. Preparation of the stock can include multiple steps that vary the solids content of the stock. For example, the thick stock can include fibrous material at a concentration of about 0.5 to 40 g / L, 10 to 40 g / L, or 20 to 40 g / L. The diluted stock can include fibrous material at a concentration of about 0.5 g / L to about 15 g / L. In some examples, the extruded starch is added to the thick stock, but alternatively, the extruded starch can be added to the diluted stock. For example, the stock can be prepared by adding extruded starch to a thick stock having a fibrous material concentration of about 20 to about 40 g / L. The thick stock is diluted to a fibrous material concentration of about 0.5 to about 15 g / L before being transferred to the wet end. In some examples, the extruded starch is added to the aqueous suspension of fibrous material before the addition of fillers and additives.

[0035] The stock may include extruded starch at a concentration of about 0.05% to about 5% by weight solids content. The stock may include about 0% to about 40% by weight inorganic filler (hereinafter referred to as "x"), expressed as ash content. The stock may optionally include one or more other additives (also referred to as "paper auxiliaries").

[0036] The fibrous material in the stock can include virgin fibers, recycled fibers, softwood fibers, hardwood fibers, non-wood fibers, or combinations thereof. The fibrous material can include dry market pulp, machine broke, recycled fibers, or combinations thereof. Any softwood or hardwood fiber commonly used in the paper industry can be used for the fibrous material. For example, the fibrous material can include mechanical pulp, bleached and unbleached chemical pulp, and / or fibrous material of any annual plant (also known as "non-wood fibrous material").

[0037] If the fibrous material contains bleached and / or unbleached chemical pulp, the pulp dewatering of the fibrous material may be 20-30SR. Pulp dewatering is measurable in SR units according to standard ISO5267-1:1999, where "SR" stands for Shopper-Riegler units. The dewatering of the fibrous material may be about 30SR, which can be achieved by refining during the pulping process. The dewatering of the fibrous material may be less than 30SR.

[0038] The extruded starch can be added to the stock as a powder or dispersion or mixture. The extruded starch preferably has a cationic charge, but can also have an anionic, zwitterionic, or neutral charge. The extruded starch can include one or more chemical or enzymatic modifications. In some examples, cationic starches are used. The extruded starch can include corn starch, wheat starch, rice starch, pea starch, potato starch, tapioca starch, barley starch, and all varieties or cultivars, such as waxy corn starch, or combinations thereof. The extruded starch can include a mixture of starch and a biopolymer, where the starch is optionally present at at least 50% or 80% by weight, and the biopolymer is optionally a cellulose or other polysaccharide such as a gum, a protein such as soy protein or gelatin or whey protein, or combinations thereof.

[0039] The extruded starch may be dried upon exiting the extruder to form a dried starch extrudate. The dried starch extrudate may be crushed and / or ground to form an extruded starch powder. The crushing and / or grinding of the dried starch extrudate may include crushing with a hammer mill and / or grinding by cryogenic grinding.

[0040] Optionally, the extruded starch powder is added to water to form an extruded starch dispersion, which may have a solids content of about 0.1% to about 50% by weight, or about 1% to about 10% by weight.

[0041] The amount of inorganic filler (ash content) added to the paper stock can be adjusted to take into account all inorganic fillers (ash content) already present, for example by using waste paper and / or coated broke as a source of fibrous material. The inorganic fillers can be inorganic pigments, e.g. metal oxides, carbonates, silicates, or combinations thereof. The inorganic fillers can include calcium carbonate, talc, kaolin, bentonite, satin white, calcium sulfate, barium sulfate, titanium dioxide, crushed lime, chalk, marble (GCC), precipitated calcium carbonate (PCC), or combinations thereof.

[0042] Optionally, inorganic fillers can be added to the stock after the addition of the extruded starch is completed. The fillers can be added when the stock is in thick stock form (e.g., when the fiber concentration is 0.5-40 g / L, 10-40 g / L, or 20-40 g / L, etc.). The fillers can be added when the stock is in thin stock form (e.g., when the fiber concentration is 5-15 g / L, etc.). The fillers can be added both at the thick stock and thin stock stages, with the ratio of thick stock addition to thin stock addition being about 5 / 1 to about 1 / 5.

[0043] The filler content (x), expressed as the ash content in formula (I), can be from about 0% to about 40% by weight, or from about 0% to about 20% by weight, based on the total dry weight of the final paper.

[0044] The paper auxiliary may include a sizing agent, a wet strength agent, a retention aid, a drainage aid, a dry strength agent, an optical brightener, a defoamer, a biocide, a paper dye, or a combination thereof. The paper auxiliary may be added to the stock when the fiber material concentration of the stock is about 5 g / L to about 15 g / L.

[0045] The extruded starch can be added at about 0.5 kg to about 50 kg per metric ton of dry fibrous material, for example, about 0.6 kg to about 20 kg of at least one extruded starch can be added. The extruded starch can be added in an amount of about 0.05% to about 5% by weight based on the dry weight of the fibrous material. The time during which the extruded starch works on the stock from addition to sheet formation can range from about 0.5 seconds to about 2 hours, or any time between about 0.5 seconds to about 2 hours. Preferably, the time can range from about 2 seconds to about 20 seconds.

[0046] The method can include stock treatment in the wet end of the papermaking process (e.g., thick and thin stock). Stock treatment with extruded starch can begin early in the papermaking process, during pulp processing, where recycled fibrous material such as dry market pulp, paper machine broke, or OCC can be re-slushed before passing to other units such as a deflaker and / or refiner. In this manner, the extruded starch can be slushed in the pulper with the dry fibrous material, or alternatively, the extruded starch can be added to the deflaker and / or refiner. The extruded starch can be added in the form of a dry powder or in the form of a dispersion.

[0047] The solids content of the web after leaving the press section can be up to 55% by weight or even higher depending on the design and operation of the forming section, the design and operation of the press section, the web speed, the type of felt used, the age of the felt, the composition of the stock, and the temperature. The solids content can increase with increasing pressure applied in the press as the paper web passes through. This pressure, and therefore the solids content of the paper web, can vary within relatively wide limits for different papermaking machines.

[0048] After the paper web leaves the press section, it can be transferred to the drying section of the paper machine. For paper grades such as graphical or packaging, the paper web can be transferred to a cascade of drying cylinders where the solids content of the paper web can increase with each cylinder. For tissue and sanitary papers, the paper sheet can be transferred to a Yankee cylinder where final drying and creping of the paper sheet can take place. The final dry content of the finished paper can be about 95%.

[0049] Cationic extruded starch can be used as a dry strength additive to improve one or more of the mechanical performance properties of paper, such as tensile strength, burst strength, short span compressive strength, and Scott bond strength. Cationic extruded starch can also be used to allow for increased production rates without creating breaks in the paper that would shut down the line. Alternatively, cationic extruded starch can be used to maintain strength at an adequate level while making other changes that can reduce cost and energy consumption but typically reduce strength. For example, reducing the paper basis weight, using shorter fibers, allowing the use of lower performance mechanically treated fibers, recycled fibers, or non-wood fibers, reducing the level of fiber refining, and increasing ash content are all desirable changes that typically reduce strength. Cationic extruded starch can be added to offset (i.e., reduce or eliminate) the loss of strength caused by one or more of the above changes.

[0050] In order to better understand the invention described herein, the following examples are provided. These examples should be understood to be for illustrative purposes only. Thus, the following examples should not be construed as limiting the scope of the invention in any way. In the following examples, the inventors have demonstrated the increase in strength over papers made with conventional starch and / or papers with solids content less than D(x) for a range of final papers of a certain weight. In Example 1B, the weight is adjusted to 100 g / m2 to ensure consistency between samples. 2 However, starches similar to Starch Sample 1 but made on a commercial scale twin screw extruder with the same starting material (cationic waxy corn starch) and the same specific mechanical energy (SME) were subsequently tested on a commercial scale tissue machine, fourdrinier and liner machine, yielding starches ranging from 16 to 205 g / m 2Final papers were produced with weights ranging from 12 to 240 g / m. Some of these final papers are described in Example 1C. Other weights are expected to produce similar results for Starch Sample 1 and the other samples described below, such as weights ranging from 12 to 240 g / m. 2 The sample numbers listed below are not consecutive because other samples were produced but were not tested according to the procedure described below.

[0051] Example Example 1A - Preparation and characterization of extruded starch products and comparative samples <Starch sample 1> Cationic waxy corn starch (Sta-Lok™ 180) available from Tate & Lyle was fed into a Buhler twin screw extruder at a flow rate of 300 kg / h and a screw speed of 600 RP. The cationic waxy corn starch had a nitrogen content of 0.35% and a moisture content of 11-13% by weight, where the weight of the cationic waxy corn starch was taken as 100% by weight. 15% by weight of water was added to the first barrel of the extruder. The extruder had 12 barrels with a controlled temperature profile of 45-45-45-40-130-130-130-135-135-135-135-135° C. The specific mechanical energy applied to the starch during extrusion was equal to 175 Wh / kg. The bulk density of the extrudate was controlled by adding 3-4% of water to barrel 12. The extrudate was discharged from two 29-hole dies and cut by a die face cutter box at 3000 RPM. The shredded extrudate was further dried by air suction conveying and then fed into a hammer mill equipped with a 3 mm sieve. After milling, the residual water content of the extruded starch powder was 7%.

[0052] <Starch sample 3> Cationic waxy corn starch (Sta-Lok™ 180) available from Tate & Lyle was fed into a Buhler twin screw extruder at a flow rate of 300 kg / h and a screw speed of 650 RPM. The cationic waxy corn starch had a nitrogen content of 0.35% and a moisture content of 11-13% by weight, where the weight of the cationic waxy corn starch was taken as 100% by weight. 12% by weight of water, 1% by weight of a 10% aqueous solution of sodium hydroxide, and 4% by weight of a 10% aqueous solution of sodium trimetaphosphate were added to the first barrel of the extruder. The extruder had 12 barrels, the temperatures of which had a controlled temperature profile of 45-45-45-40-130-130-130-135-135-135-135-135° C. The specific mechanical energy applied to the starch during extrusion was equal to 244 Wh / kg. The extrudate exited two 29-hole dies and was cut by a die face cutter box at 3000 RPM. The shredded extrudate was further dried by air suction conveying and then fed into a hammer mill equipped with a 3 mm sieve. After milling, the residual water content of the extruded starch powder was 7%.

[0053] <Starch sample 4> Moist cationic waxy corn starch (Interbond™ C) available from Tate & Lyle was fed into a Buhler twin screw extruder at a flow rate of 300 kg / h and a screw speed of 600 RPM. The cationic waxy corn starch had a nitrogen content of 0.27% and a moisture content of 11-13% by weight, where the weight of the cationic waxy corn starch was taken as 100% by weight. 12% by weight of water was added to the first barrel of the extruder. The extruder had 12 barrels with a controlled temperature profile of 45-45-45-40-130-130-130-135-135-135-135-135° C. The specific mechanical energy applied to the starch during extrusion was equal to 214 Wh / kg. The bulk density of the extrudate was controlled by adding 3-4% water to barrel 12. The extrudate exited two 29-hole dies and was cut by a die face cutter box at 3000 RPM. The shredded extrudate was further dried by air suction conveying and then fed into a hammer mill equipped with a 3 mm sieve. After milling, the residual water content of the extruded starch powder was 7%.

[0054] <Starch sample 5> Cationic potato starch (SolBond PC 80) from Solam was fed into a Buhler twin screw extruder at a flow rate of 300 kg / h and a screw speed of 600 RPM. The cationic waxy corn starch had a nitrogen content of 0.64% and a moisture content of 11-13% by weight, based on the weight of the cationic waxy corn starch. 6% water and 4.5% glycerol were added to the first barrel of the extruder. The extruder had 12 barrels with a controlled temperature profile of 45-45-45-40-130-130-130-135-135-135-135-135°C. The specific mechanical energy applied to the starch during extrusion was equal to 206 Wh / kg. The extrudate exited two 29-hole dies and was cut by a die face cutter box at 3000 RPM. The shredded extrudate was further dried by air suction conveying and then fed into a hammer mill equipped with a 3 mm sieve. After milling, the residual water content of the extruded starch powder was 7%.

[0055] <Starch sample 10> Cationic waxy corn starch (Sta-Lok™ 180) available from Tate & Lyle was fed into a Buhler twin screw extruder at a flow rate of 200 kg / h and a screw speed of 550 RPM. The cationic waxy corn starch had a nitrogen content of 0.35% and a moisture content of 11-13% by weight, where the weight of the cationic waxy corn starch was taken as 100% by weight. 6% by weight of water and 0.6% by weight of a 10% aqueous phosphoric acid solution were added to the first barrel of the extruder. The extruder had 12 barrels with a controlled temperature profile of 45-45-45-40-130-130-130-135-135-135-135-135° C. The specific mechanical energy applied to the starch during extrusion was equal to 239 Wh / kg. The extrudate exited two 29-hole dies and was cut by a die face cutter box at 3000 RPM. The shredded extrudate was further dried by air suction conveying and then fed into a hammer mill equipped with a 3 mm sieve. After milling, the residual water content of the extruded starch powder was 7%.

[0056] <Starch sample 11> Cationic waxy corn starch (Sta-Lok™ 180) available from Tate & Lyle was fed into a Buhler twin screw extruder at a flow rate of 200 kg / h and a screw speed of 550 RPM. The cationic waxy corn starch had a nitrogen content of 0.35% and a moisture content of 11-13% by weight, where the weight of the cationic waxy corn starch was taken as 100% by weight. 24% by weight of water was added to the first barrel of the extruder. The extruder had 12 barrels with a controlled temperature profile of 45-45-45-40-130-130-130-135-135-135-135-135° C. The specific mechanical energy applied to the starch during extrusion was equal to 180 Wh / kg. The extrudate exited two 29-hole dies and was cut by a die face cutter box at 3000 RPM. The shredded extrudate was further dried by air suction conveying and then fed into a hammer mill equipped with a 3 mm sieve. After milling, the residual water content of the extruded starch powder was 7%.

[0057] <Starch sample 12> Cationic waxy corn starch (Sta-Lok™ 180) available from Tate & Lyle was fed into a Buhler twin screw extruder at a flow rate of 200 kg / h and a screw speed of 550 RPM. The cationic waxy corn starch had a nitrogen content of 0.35% and a moisture content of 11-13% by weight, where the weight of the cationic waxy corn starch was taken as 100% by weight. 12% by weight of water, 4% by weight of a 10% aqueous solution of sodium hydroxide, and 1.5% by weight of a 5% aqueous solution of sodium trimetaphosphate were added to the first barrel of the extruder. The extruder had 12 barrels, the temperatures of which had a controlled temperature profile of 45-45-45-40-130-130-130-135-135-135-135-135° C. The specific mechanical energy applied to the starch during extrusion was equal to 261 Wh / kg. The extrudate exited two 29-hole dies and was cut by a die face cutter box at 3000 RPM. The shredded extrudate was further dried by air suction conveying and then fed into a hammer mill equipped with a 3 mm sieve. After milling, the residual water content of the extruded starch powder was 7%.

[0058] <Starch sample 13> Cationic waxy corn starch (Sta-Lok™ 180) available from Tate & Lyle was fed into a Buhler twin screw extruder at a flow rate of 200 kg / h and a screw speed of 550 RPM. The cationic waxy corn starch had a nitrogen content of 0.35% and a moisture content of 11-13% by weight, where the weight of the cationic waxy corn starch was taken as 100% by weight. 12% by weight of water, 4% by weight of a 10% aqueous solution of sodium hydroxide, and 1% by weight of a 5% aqueous solution of sodium trimetaphosphate were added to the first barrel of the extruder. The extruder had 12 barrels, the temperatures of which had a controlled temperature profile of 45-45-45-40-130-130-130-135-135-135-135-135° C. The specific mechanical energy applied to the starch during extrusion was equal to 269 Wh / kg. The extrudate exited two 29-hole dies and was cut by a die face cutter box at 3000 RPM. The shredded extrudate was further dried by air suction conveying and then fed into a hammer mill equipped with a 3 mm sieve. After milling, the residual water content of the extruded starch powder was 7%.

[0059] <Starch sample 15> Cationic waxy corn starch (Cato™ 235) available from Ingredion was fed into a Buhler twin screw extruder at a flow rate of 200 kg / h and a screw speed of 350 RP. The cationic waxy corn starch had a nitrogen content of 0.25% and a moisture content of 11-13% by weight, where the weight of the cationic waxy corn starch was taken as 100% by weight. 18% water was added to the first barrel of the extruder. The extruder had 12 barrels, the temperatures of which had a controlled temperature profile of 45-45-45-40-130-130-130-135-135-135-135-135° C. The specific mechanical energy applied to the starch during extrusion was equal to 139 Wh / kg. The bulk density of the extrudate was controlled by adding 1.5% water by weight to barrel 12. The extrudate was discharged from two 29-hole dies and cut by a die face cutter box at 3000 RPM. The shredded extrudate was further dried by air suction conveying and then fed into a hammer mill equipped with a 3 mm sieve. After milling, the residual water content of the extruded starch powder was 7%.

[0060] <Starch sample 15> Cationic waxy corn starch (Cato™ 235) available from Ingredion was fed into a Buhler twin screw extruder at a flow rate of 200 kg / h and a screw speed of 350 RP. The cationic waxy corn starch had a nitrogen content of 0.25% and a moisture content of 11-13% by weight, where the weight of the cationic waxy corn starch was taken as 100% by weight. 18% water was added to the first barrel of the extruder. The extruder had 12 barrels, the temperatures of which had a controlled temperature profile of 45-45-45-40-130-130-130-135-135-135-135-135° C. The specific mechanical energy applied to the starch during extrusion was equal to 180 Wh / kg. The bulk density of the extrudate was controlled by adding 1.5% water to barrel 12. The extrudate was discharged from two 29-hole dies and cut by a die face cutter box at 3000 RPM. The shredded extrudate was further dried by air suction conveying and then fed into a hammer mill equipped with a 3 mm sieve. After milling, the residual water content of the extruded starch powder was 7%.

[0061] Comparative starch sample <Starch sample 17> Starch Sample 17 is a waxy corn starch (Sta-Lok™ 180) having 0.35% nitrogen and 11-13% moisture content, commercially available from Tate & Lyle Co. Sample 17 is a granular starch and was used as the input starch for the extrusion process in the preparation of Samples 1, 3, 11, 12, and 13.

[0062] <Starch Sample 18> Starch Sample 18 is a cold water soluble starch (Sta-Lok™ 280) made from cationic waxy corn starch having a nitrogen content of 0.35% and is commercially available from Tate & Lyle Co. This starch sample was included in the testing program to demonstrate the differences between the extrusion process and existing methods for gelatinizing starch.

[0063] Fibraffin K Fibrafin K is a cationic potato starch available from Suedstaerke and commonly used in the paper industry for dry strength applications, and was used. Fibrafin K was supplied as granular starch and heated to a starch suspension in a jet cooker or by heating under atmospheric conditions.

[0064] See Table 3 for the composition and physical properties of the starch samples. Table 3: Composition and physical properties of the starch samples prepared. [Table 4] Table 3 Legend: NA: None ( * ) Viscosity (Brookfield, 100 RPM, 25% solids, 25°C, suspension made with 0.8% solution of sodium carbonate (Na2CO3)) ( ** ) Rapidly soluble starch: (4g dry starch was added to 200ml deionized water, stirred at 600 RPM for 2 minutes, centrifuged at 3000 RPM for 15 minutes, 100ml of the supernatant was decanted or pipetted into a dish and oven dried at 110°C to determine soluble starch) ( *** ) In the case of Sample 17 (comparative example), a suspension of starch granules with a solids content of 25% was made using a 0.8% solution of Na2CO3 (sodium carbonate). The suspension was heated on a hot plate for 30 minutes at 90° C. This resulted in a gel which could not be analyzed to measure viscosity and molecular weight. ( **** ) The amount of cross-linking agent added during the extrusion process influenced the level of rapid starch solubility RSS (for the same input starch). The greater the degree of cross-linking, the lower the level of RSS.

[0065] Example 1B - Handmade Sheet Preparation and Testing <Preparation of paper stock> The raw material (stock) for the production of hand sheets was obtained by beating a paper sheet in a pulper. The paper sheet had a basis weight of 100 g / m 2 The raw paper used was of the specification "Testliner 2" with a solids content of 1.0%. The pulping process was carried out by dissolving the paper sheets with tap water to a solids content of about 3.5% and then mechanically processing them in a pulper. The dewatering of the paper pulp at the end of the pulping process was about 43° SR. The pulp dewatering was measured in SR units according to the standard ISO 5267-1:1999, where "SR" stands for Shopper-Riegler units.

[0066] <Preparation of starch dispersion> Extruded starch powder dispersions with 10% solids were prepared in a glass beaker using starch samples 1, 3, 4, 5, 10, 11, 12, 13, 15, and 16. This was done by mixing 50 g of extruded starch powder with 450 g of tap water (at a temperature of about 20° C.) using a propeller mixer (ER10) at 1000 RPM for 30 minutes. Immediately after the stock treatment, the extruded starch powder dispersions were subjected to a two-step dilution process. 50 ml of the 10% solids dispersion was transferred to a separate glass beaker. The separated dispersion was then diluted to 1% solids by adding 450 g of tap water. This dilution procedure was repeated by mixing 50 ml of the diluted dispersion (1% solids) with 450 g of tap water again, which resulted in more dilute dispersions with 0.1% solids. The highly diluted extruded starch powder dispersion was then ready for addition to the paper stock.

[0067] For sample 17 and Fibrafin K, a comparative starch suspension with 1% solids was prepared in a glass beaker by mixing 5 g of starch powder with 495 g of tap water (at a temperature of about 20°C) using a propeller mixer (ER10) at 500 RPM for 15 minutes. The glass beaker containing the comparative starch suspension was then transferred to a heated water bath. The temperature of the water bath was kept at 92°C-95°C. The beaker was left in the water bath for 30 minutes while stirring at 500 RPM. Immediately after the stock treatment, 50 ml of the heated comparative starch solution (1% solids) was diluted with 450 g of tap water, resulting in a starch solution with 0.1% solids. The highly diluted comparative starch solution was then ready for addition to the stock.

[0068] For sample 18 (starch dispersion with 30% solids), 166.7 g of the original comparative starch dispersion with 30% solids was mixed with 332.3 g of tap water (at a temperature of approximately 20° C.) in a glass beaker using a propeller mixer (ER10) at 1000 RPM for 30 minutes to produce a comparative starch dispersion with 10% solids. Immediately after the stock treatment, this starch dispersion went through a two-stage dilution process. 50 ml of the 10% solids starch dispersion was transferred to a separate glass beaker. The separated dispersion was then diluted to 1% solids by adding 450 g of tap water. This dilution procedure was repeated by again mixing 50 ml of the diluted comparative starch dispersion (1% solids) with 450 g of tap water, resulting in a more dilute comparative starch dispersion with a solids content of 0.1%. The more dilute comparative starch dispersion was then ready for addition to the paper stock.

[0069] <Paper material processing> Separate glass beakers, each containing 500 g of 3.5% solids pulp suspension, were prepared for treatment with each starch, including the extruded and comparative starches. Two different starch loadings were used. The lower starch loading was 5 g dry starch per kg dry pulp, corresponding to 87.5 g starch dispersion or solution with a solids content of 0.1%. The higher starch loading was 10 g dry starch per kg dry pulp, corresponding to 175 g starch suspension or solution with a solids content of 0.1%.

[0070] After adding starch (either extruded starch dispersion or comparative starch solution / dispersion) to the stock at the respective dosage levels, the ingredients were mixed using a propeller mixer at 100 RPM for 30 minutes. No retention aid was added.

[0071] <Handmade sheet production> Just before handsheet production, a portion of the treated stock with each type of starch and each dosage was taken from the glass beaker and further diluted to a solids content of 0.25% (Figure 4, test samples 3-54). Handsheets were produced using a Rapid Koethen handsheet former (ISO 5269-2:2004). The amount of pulp slurry added to the handsheet former was 100 g / m 2 The hand-made sheet was adjusted to a basis weight of 200 mm.

[0072] <Blank comparison example> To generate blank comparative examples for the starch-treated cases, additional handsheets were made without any starch treatment (see Table 4, Tests No. 1 and 2). For the blank comparative examples, a cationic polyacrylamide (Percol™ provided by Solenis) was added as a retention aid to the pulp suspension. The amount added was 0.5 g (polymer solution, as received) per kg dry pulp. This treatment maintained the solids retention in the blank sheets at a similar level to that observed in the starch-treated sheets. After the addition of the retention aid, the pulp suspension was passed through the dilution and handsheet making processes described above.

[0073] <Pressing and drying> After being discharged from the Rapid Köthen handsheet former, the wet handsheets (starch treated and blank samples) were processed in a hydraulic press to achieve higher dry content. Thus, the handsheets were sandwiched between two sheets of blotter paper and pressed in a hydraulic press at 6 bar for 30 seconds. After the first pressing step, the dry content was typically found to be in the range of 42%-44%. At the test points targeting higher dry content, the wet blotter paper was removed from the pressed handsheets and replaced with a new pair of dry blotter sheets, after which the pressing process was repeated. After the second pressing step, the dry content was typically found to be in the range of 47%-48%. After pressing, the handsheets were dried at 93°C for 6 minutes using a standard light-duty dryer for handsheets. After drying, the handsheets were left under controlled environmental conditions in an artificial climate chamber at 23°C and 50% relative humidity for at least 12 hours.

[0074] The mechanical properties of the hand-made sheets were characterized by standard methods as follows.

[0075] <Short span compression test> To measure the short span compressive strength (SCT), the dried hand sheets were cut into strips with a width of 15 mm and a length of 125 mm. Six strips were taken from each hand sheet. SCT was tested according to standard ISO9895:2008. Eighteen strips from three hand sheets were used to determine a statistical average for one data point.

[0076] <Burst Strength> Burst strength was measured according to standard ISO2759:2014. Individual handsheets were cut into four sections. 12 sections from three handsheets were used to determine a statistical average for one data point.

[0077] Grammage: As specified in standard ISO536:2019.

[0078] Ash content: As specified in standard ISO1762:2019.

[0079] <Result> The test results for 54 test points are summarized in Table 4, which shows the starch treated samples at two addition levels (5 g / kg and 10 g / kg) as well as the hand sheets pressed at two dry matter content levels (see test samples no. 3-54) and the blanks to which these two dry matter content levels are compared. The minimum solids content D(x) (as determined by formula (1)) is found to be about 45.3%, since the variation in ash content between the different test sample numbers in the table was small. As shown in Table 4, test numbers 3, 4, 7, 8, 11, 12, 15, 16, 19, 20, 23, 24, 27, 28, 31, 32, 35, 36, 39, 40 correspond to a level of solids content of D(x) = 45.3% or more, test numbers 5, 6, 9, 10, 13, 14, 17, 18, 21, 22, 25, 26, 29, 30, 33, 34, 37, 38, 41, 42 correspond to a level of dry matter content of D(x) = less than 45.3%. Test numbers 23, 24, 25, 26, 47, 48, 49, 50, 51, 52, 53, 54 did not use extruded starch.

[0080] <Analysis and Conclusions> The test resulted in solids content after pressing either below the minimum solids content defined by "D(x)" (-1.3% to -3%) or above the minimum solids content defined by "D(x)". A difference of 1.3% to 3% below the minimum solids content of 45.3% and a difference of 1.4% to 2.6% above the minimum solids content of 45.3% are considered significant. The blank specimens (specimens 1 and 2) did not show what would be considered a significant response in strength parameters (SCT and burst) when the solids content was increased from "below" to "above" the minimum solids content defined by "D(x)" for the samples under test.

[0081] Tests performed with cooked starch comparison samples (see Table 4, test samples 23-26 and test samples 47-50) showed some increase in strength parameters when the starch addition level was increased from 5 to 10 g / kg dry pulp. However, these tests did not indicate what would be considered a significant response in strength parameters (SCT and burst) when the solids content was increased from "below" to "above" the minimum solids content defined by "D(x)" for the samples tested.

[0082] For the specimens containing extruded starch treated samples (Table 4, specimens 3-22 and 27-46), what was considered to be a significant response in strength parameters (SCT and burst) was observed when the solids content increased from "below" to "above" the minimum solids content defined by "D(x)" for the tested samples, both at low (5 / kg) and high (10 / kg) starch addition levels. In Table 4, the increase in strength averaged 6% to 8. This response is considered to be significantly greater than that predicted in the context of using cooked granules with the comparative samples (see Table 4, specimens 23-26 and 47-50).

[0083] The cationic cornstarch granules (sample 17) prepared by heating for test samples Nos. 47-50 have also been used as base starch for processing in an extruder (sample 1) and to carry out test samples Nos. 3-6. When starch is used as a dry strength agent in papermaking, based on the above test results, it has been concluded that processing the starch in an extruder produces what is considered to be a significant increase in paper strength compared to processing the starch using conventional heating methods.

[0084] It was also observed that industrial gelatinized starches made from cationic corn starch with the same cationic charge density (see Table 4, Sample 18, Tests Nos. 51-54) did not show the same degree of strength increase compared to handsheets made with extruded starch treated samples as the solids content increased from "below" to "above" the minimum solids content defined by "D(x)" for the samples tested. These results suggest that treating starch to make it cold water soluble (e.g., the gelatinization process) is not a step in the extrusion process that affects the dry strength performance of extruded starch in paper.

[0085] It was observed that the test specimens with handsheets containing extruded starch Sample 1 showed better strength performance than the comparative pre-heated starches and comparative heated granular starches based on the same starch type and cationicity, see Figure 5. It was also observed that the difference in strength performance between handsheets containing extruded starch Sample 1 (non-crosslinked) and Sample 12 (crosslinked) was not significantly different, see Figures 3 and 4. Furthermore, a plateau in strength performance was observed for all the test specimens when going from 5 g / kg to 10 g / kg. Based on these results, it is believed that (i) the performance of paper products containing extruded starch does not depend heavily on cationicity, as the products with the highest charge showed slightly lower strength performance (see Figure 1); (ii) the performance of paper products containing extruded starch does not depend heavily on maximizing molecular weight (MW), as the products with the highest MW showed reduced performance (see Figure 2); and (iii) the performance of paper products containing extruded starch does not depend heavily on changes in crosslinking, as crosslinking was not found to result in what would be considered a significant increase in strength.

[0086] Test specimens using handsheets containing extruded starch samples 1 and 2 were observed to show what was considered to be a significant increase in strength properties for both starch addition levels (5 kg / t and 10 kg / t) when going from low dry content (<44%) to high dry content (>46%). What was considered to be a very small increase in strength properties was observed for the comparison starches, i.e. cooked granular starch (sample 17) and cold water soluble starch (sample 18). See Figure 5. Table 4 - Composition and mechanical properties of the handmade sheets produced [Table 5] JPEG2025511888000007.jpg111163

[0087] Example 1C - Machine-made Paper <Paper sample 1> Using 100% RCP (recovered paper) fiber with added extruded cationic starch, the basis weight is 15.5-16.5g / m 2 Tissues with extruded cationic starch (GSM) were produced. The extruded cationic starch was different from 2, 4 and 6 kg / T. As cationic starch loading increased, the zeta potential increased from -12.4 mV to 2.4 mV and the cationic demand decreased from 78 uEq / L to 3 Eq / L. The retention increased from 75.2% to 88.9%. The cationic starch is effective in neutralizing the charge on the fiber surface. The improved retention as above also assists in reducing the BOD of the wet end system.

[0088] <Paper sample 2> In one example, standard waxy corn starch (Interstarch) was modified to give a nitrogen content of 0.35% by weight and a molecular weight of 4×10 6Daltons and 92% RSS. The cationic extruded starch was added to a machine producing tissue paper from virgin fibers with the following composition: 40% softwood kraft fiber pulp (long fiber), 40% kraft hardwood pulp (short fiber), and 20% bleached chemi-thermodynamic pulp (BCTMP fiber).

[0089] The paper machine is 17.5g / m 2 and was producing tissue paper at a speed of 1650 m / min. The tissue machine was a dual-headbox system, which has two headboxes that simultaneously add pulp slurry to the wire. In this example, one of the headboxes fed primarily long fibers and the second fed primarily short fibers.

[0090] Additionally, cationic polyacrylamide (cPAM) and polyethyleneimine (PEI) have been added to systems including what are also referred to in the paper industry as "retention systems" or "retention systems."

[0091] Extruded starch was added only to the long fiber system. It was added before entering the long fiber machine chest, which in turn was added before the refiner, refiner chest, or head tank. 10 kg of extruded starch was added per ton of dried long fiber pulp at the long fiber line. This resulted in a total of 5 kg of extruded starch added per ton of finished tissue paper. The extruded starch was added over a 23 hour period.

[0092] No inorganic fillers were added. The solids content, also called dryness, immediately after the press section was measured to be between 44% and 46% solids during the addition of extruded starch. The ash content was essentially 0%. The press solids exceeded the minimum press solids D=46+(0-10)x0.3=43%.

[0093] The tensile strength of the tissue paper was measured multiple times over the period before and during the addition of the extruded starch. The tensile strength of the tissue paper was measured in both the machine direction (direction of the moving wire) and the cross machine direction (perpendicular to the direction of the wire). The tensile strength measurements were averaged for the period before and during the addition of the extruded starch.

[0094] The average tensile strength measured in the machine direction of the tissue paper without extruded starch was 129 N / m (Newtons per meter).

[0095] The average tensile strength measured in the cross machine direction for tissue paper without extruded starch was 65 N / m.

[0096] The average tensile strength measured in the machine direction of tissue paper made with the extruded starch was 159 N / m (Newtons per meter).

[0097] The average tensile strength measured in the cross machine direction of tissue paper made with the extruded starch was 86 N / m.

[0098] The addition of extruded starch resulted in a 23% increase in tensile strength in the machine direction and a 32% increase in tensile strength in the cross direction.

[0099] The dusting tendency of tissue papers was also examined during periods of extruded starch addition and compared to periods without extruded starch addition. Dusting is a measure of fines and fibers that can break away from tissue papers. Improved binding of fines and fibers to the tissue matrix results in less dusting during the manufacturing process and end use of the tissue. Dusting tendency is measured by the amount of dust that can break away from 81 cm of tissue with constant air flow for a fixed period of time. 2 It is assessed by measuring the fines and fibres that break off and are collected from the sample. 2The sample is weighed and placed into a collection chamber. A constant flow of air is then directed through the chamber and over the sample. The airflow exiting the chamber is filtered to remove loose fines and fibers from the air. The collected fines and fibers are weighed and reported as the amount of loose fines and fibers as a percentage of the original tissue.

[0100] The average % dust from tissue papers made without extruded starch was determined to be 1.3%.

[0101] The average % dust from tissue papers made with extruded starch was determined to be 1.1%.

[0102] Softness of tissue paper is a desirable characteristic for end users of tissue paper. Those of ordinary skill in the art of papermaking will typically recognize that there is an inverse relationship between tissue strength and softness, i.e., as the tensile strength of the tissue paper increases, the softness of the tissue paper decreases. Softness was measured with a Tissue Softness Analyzer manufactured by Emtec Electronic GmbH. The Tissue Softness Analyzer measures micro-surface roughness, macro-surface roughness, and stiffness. These parameters have been extensively evaluated in human panel tests to develop algorithms that correlate the characteristics to human perception of softness to generate a quantitative value as an index of softness (also called "hand"). The higher this "hand" value, the softer the tissue is considered to be.

[0103] The tissue paper made without extruded starch had a softness measurement of 74.

[0104] The tissue paper made with the extruded starch had a softness measurement of 75.

[0105] The application of extruded starch unexpectedly resulted in a significant improvement in tensile strength without any loss in tissue softness.

[0106] <Paper sample 3> In another example, standard waxy starch (Interstarch) was modified to produce a starch with a nitrogen content of 0.35% by weight and a molecular weight of 4×10 6 The cationic extruded starch was extruded to yield a 100% PP, 100% Dalton, and 92% RSS. The cationic extruded starch was added to a machine making hand towel paper with 70% hardwood and 30% softwood fibers. Alternatively, hand towel paper was made with a composition of 60-70% hardwood, 3% softwood, and up to 10% BCTMP. The BCTMP fibers are short and low cost, but their use results in a lower tensile strength end product.

[0107] The machine is fitted with a two-ply headbox for a maximum of 18 g / m 2 The company was manufacturing hand towels.

[0108] Additionally, cationic polyacrylamide (cPAM) and polyethyleneimine (PEI) were added as part of the retention system and wet strength additive.

[0109] The extruded starch was added to the long fiber system at a total addition of 5 kg of extruded starch per ton of finished hand towels, which was added prior to entering the long fiber machine chest, which in turn was added prior to the refiner, refiner chest, or head tank.

[0110] No inorganic fillers were added. The solids content of the web, also referred to as web dryness, immediately after the press section and during the addition of the extruded starch was measured to be 44%-46%. The ash content was measured to be essentially 0%. The press solids exceeded the minimum press solids D=46+(0-10)x0.3=43%.

[0111] 18g / m 2 The tensile strength of the hand towels was measured over a period of one year prior to the addition of extruded starch (referred to as the "control") and multiple times thereafter during the addition of extruded starch (referred to as the "test"). The tensile strength of the hand towels was measured in both the machine direction (direction of the moving wire) and the cross machine direction (perpendicular to the direction of the wire).

[0112] When the hand towels were made with 70% hardwood fiber and 30% softwood fiber, the tensile strength of the furnish was as follows: [Table 6] When the hand towels were made with 60% hardwood fiber, 30% softwood fiber, and 10% BCTMP, the tensile strength was as follows: [Table 7]

[0113] The addition of extruded starch resulted in increased tensile strength in both the machine and cross machine directions. Moreover, the results also suggest that the use of 5 kg / ton of extruded starch in a low-cost stock formulation with 10% BCTMP can maintain the tensile strength properties of tissue made without BCTMP.

[0114] <Paper sample 4> In another example, standard waxy starch (Interstarch) was modified and extruded to give a nitrogen content of 0.35% by weight and a molecular weight of 4×10 6Daltons and an RSS value of 92% were achieved. This cationic extruded starch was added to a machine producing tissue paper from 100% deinked pulp (DIP) slurry. Deinked pulp is made from fibers collected from various sources after their primary use has ended. The fibers often contain various levels of inorganic mineral pigments, also called fillers. The amount of pigment carried through the deinking process can be controlled to some extent. Retaining the filler in the DIP typically causes lower achievable strength properties, as the filler does not contribute to the strength of the sheet. On the other hand, removal of the filler results in a reduction in the overall waste paper yield from the deinking process.

[0115] The above machine is 15.6g / m 2 and produced tissue paper at a speed of 1400 meters per minute. This tissue machine is called a gap former. In this system, a headbox feeds the pulp slurry between two moving wires (an upper wire and a lower wire) which carry and "drain" or "dewater" the slurry. After the forming section, the formed mat is transferred to the press station for further mechanical dewatering.

[0116] In this example, there are no chemicals used as yield aid systems to enhance yield.

[0117] In this example, the ash content was 2.5% and the basis weight was 15.6 g / m2 during the three months immediately preceding the period in which the extruded starch was added. 2 The ash was carried by the deinked pulp. Extruded starch was added to the system at the outlet of the mixing chest. The amount of extruded starch was adjusted to 2.7 kg per tonne of finished tissue. The extruded starch was added over a period of 32 hours.

[0118] The addition of extruded starch increased the retention of ash content in tissue paper from 2.5% to 3.3%, which represents an increase in yield. Furthermore, the basis weight of tissue paper produced during the addition of extruded starch was 15.3 g / m 2 One of ordinary skill in the art of papermaking would expect that an increase in ash content would lead to a loss in tensile strength in tissue paper. Similarly, a basis weight of 15.6 g / m 2 from 15.3 g / m 2 Reducing the thickness to 0.2 mm is expected to lead to a decrease in tensile strength.

[0119] The solids content measured immediately after the press section was 45%-47%. This press solids content exceeds the minimum press solids content for the papermaking process described in this disclosure. Minimum press solids content D=46+(3.3-10)×0.3=43.4%.

[0120] The tensile strength of the tissue papers was measured for three months before the addition of the extruded starch and for the period during the addition of the extruded starch. The tensile strength of the tissue papers is measured in both the machine direction (direction of the moving wire) and the cross machine direction (perpendicular to the direction of the wire). The tensile strength measurements were averaged for the three months before the addition of the extruded starch and for the period during the addition of the extruded starch.

[0121] The average machine direction tensile strength of the tissue paper without extruded starch was 178 N / m (Newtons per meter).

[0122] The average cross machine tensile strength of the tissue paper without extruded starch was 89 N / m.

[0123] The average machine direction tensile strength of tissue papers made using the extruded starch was 189 N / m (Newtons per meter).

[0124] The average cross machine tensile strength of tissue papers made using the extruded starch was 83 N / m.

[0125] Unexpectedly, the increase in ash content and decrease in basis weight during the addition of 2.7 kg / tonne of extruded starch did not lead to a loss in the overall tensile strength of the tissue.

[0126] Furthermore, tissue softness improved during the addition of 2.7 kg / tonne of extruded starch: 55.6% softness during the addition of extruded starch compared to 51.4% softness during the three-month average for this grade before the addition of extruded starch.

[0127] <Paper sample 5> In another example, a linerboard was made with a base ply made from 100% recycled OCC (old corrugated container) stock and a white top ply made from 100% virgin hardwood pulp and added precipitated calcium carbonate (PCC) The linerboard is used to make corrugated boxes.

[0128] The paper machine is designed to produce board with a total basis weight of 175 g / m 2 The machine will produce a linerboard grade of 10 ...

[0129] Extruded cationic waxy-cone with nitrogen content of 0.35% by weight, molecular weight of 4 x 106 Daltons, and RSS value of 92% as described for paper samples 2-4 was added to the inlet of the base ply mixing chest only in a finished 4 kg / ton linerboard over a period of time (referred to as the test sample). No adjustments were made to the top ply (printed ply) or base ply weight ratios. The addition of extruded starch reduced the amount of retention aid required.

[0130] The ash content measured during the addition of extruded starch was 15.5%. The solids content measured immediately after the press section was measured to be between 48% and 49%. This press solids content exceeds the minimum press solids content of the papermaking process described in this disclosure. Minimum press solids content D = 46 + (15.5 - 10) x 0.3 = 47.7%.

[0131] The important tests used to evaluate the strength of linerboard are the Short Span Compression Test (SCT), the Burst Test, and the Scott Bond Test.

[0132] SCT is performed by cutting a 15mm wide strip from the manufactured linerboard and holding the sample between two clamps (usually 0.7mm apart). A compressive force is applied to the sample. The maximum compressive strength is recorded in kilonewtons per metre. The basis weight is divided and the resulting units are Newton metres per gram (Nm / g).

[0133] Burst pressure is another metric used to determine the strength of linerboard and the resulting corrugated board. It is used as an indicator of a packaging container's ability to withstand stresses during shipping. It is defined as the maximum pressure that the surface of the linerboard can withstand in a vertical direction before bursting. Burst strength is measured in kilopascal meters squared (kPa m 2 / g).

[0134] The Scott Bond test is a measure of the energy required to very quickly peel a linerboard specimen. The force is applied by a pendulum of known mass and speed. The pendulum device provides a rotational tensile stress, which results in minimal shear stress and rupture in the z-direction. The energy absorbed by the stretching or elongation of the fiber matrix while the specimen ruptures in the z-direction is recorded. The stronger the fiber network, the greater the amount of energy absorbed during specimen rupture. The Scott Bond is measured in Joules per square meter (J / m 2The results are shown below: [Table 8]

[0135] The results showed that even though the ash content increased by 15.6% over the test period, which had a negative effect on the strength of the linerboard, the extruded cationic starch increased the strength measured by SCT (3.4% increase), strength measured by Burst (8.9% increase), and strength measured by Scott Bond (21.8% increase).

[0136] Previous attempts to increase the strength of this machine were made by adding 3Kg / t of jet-cooked cationic starch to the base ply, but this did not affect the strength as measured by SCT, Burst and Scottbond.

[0137] <Paper sample 6> In another example, standard waxy starch (Interstarch) was modified and extruded to give a nitrogen content of 0.35% by weight, a molecular weight of 4X10^6 Daltons, and an RSS value of 92%. The cationic extruded starch was added to a machine producing graphic printing paper. The pulp slurry consisted of 75% short fibers, 23% long fibers, and 2% BCTMP pulp. In addition, ground calcium carbonate (GCC) "filler" was added to the pulp slurry to give a final paper ash content of 31%. In addition, an anionic polyacrylamide emulsion was added as a retention system. In addition, 8 kg / ton of the above cationic starch was added. The furnish was added to the fourdrinier wire through the headbox. The total basis weight of the finished paper was 120 g / m2. 2 The paper is produced at a speed of 680 m / min.

[0138] In this example, 4.3 kg of extruded starch was added per tonne of finished paper. The extruded starch was added at the outlet of the staple chest. The strength of the paper was tested before, during and after the addition of the extruded starch. The strength tests showed that the Scott Bond of the paper produced with the addition of 4.3 kg / tonne of extruded starch was 35% higher than the periods produced before and after the addition of extruded starch. In addition, the tensile strength of the paper produced during the period of extruded starch addition was 15% higher than the paper produced without the addition of extruded starch.

[0139] Previous attempts to increase the strength of paper by adding conventional cooked starch have not provided any additional strength.

[0140] <Paper sample 7> 16.8g / m 2 Tissues of weight were made with 100% DIP furnish. Target strengths were 130-172 N / m machine direction (MD) tensile strength and 65-68 N / m cross direction (CD) tensile strength. The addition of 2 kg / T of extruded cationic waxy corn starch resulted in 158 N / m MD tensile strength and 80 N / m CD tensile strength. The addition of 2 kg / T of extruded cationic Solbond™ PC50 potato starch resulted in 154 N / m MD tensile strength and 75 N / m CD tensile strength. The addition of 2.4 kg / T of extruded cationic Raisamyl™ 80051 wheat starch resulted in 153 N / m MD tensile strength and 77 N / m CD tensile strength. Corn, potato and wheat starches all achieved or exceeded the target strengths at acceptable addition levels.

[0141] The embodiments described herein are for illustrative purposes only, and those skilled in the art may make changes, modifications, and / or variations to the particular embodiments. The claims should not be limited by the particular embodiments described herein, but should be construed consistent with the entire specification.

Claims

1. A method for making paper, The steps include preparing a pulp comprising a fibrous material, extruded starch, moisture, and optionally one or more inorganic fillers, The steps include forming a paper web from the aforementioned paper material, The steps include pressing the aforementioned paper web, The steps include drying the aforementioned paper web, It has, The paper web after pressing has a solid content of at least the same unit weight % as the minimum solid content D(x) defined by the following formula (I): D(x)=46+(x-10)×0.3 (I) However, in the same formula, x is the ash content of the dried paper. A method characterized by the following:

2. The aforementioned ash content is as defined in ISO 1762:2019. The method according to claim 1.

3. The weight of the aforementioned paper is 12 to 240 g / m². ２ It is within the range of, The method according to claim 1.

4. This includes adding extruded starch to the aqueous suspension of the fibrous material. The method according to claim 1.

5. The concentration of the fibrous material in the aforementioned paper stock before draining is in the range of 0.5 g / L to 15 g / L. The method according to any one of claims 1 to 4.

6. The method involves preparing a thick paper stock with an initial concentration of fibrous material in the range of 0.5 g / L to 40 g / L, 10 to 40 g / L, or 20 to 40 g / L, and then diluting the thick paper stock to a concentration in the range of 0.5 g / L to 15 g / L. The method according to claim 5.

7. The concentration of the inorganic filler in the aforementioned thick paper stock is in the range of 0 to 20 g / L. The method according to claim 6.

8. The aforementioned pulp contains the extruded starch in an amount of 0.05 to 5% by weight or 0.06 to 2% by weight, based on the weight of the dried fiber material. The method according to claim 4.

9. The aforementioned extruded starch is not cross-linked starch. The method according to claim 4 or 8.

10. The aforementioned extruded starch is cross-linked starch. The method according to claim 4 or 8.

11. The extruded starch is a cationic starch. The method according to claim 4 or 8.

12. The aforementioned fibrous material includes coniferous tree fibers, hardwood fibers, non-wood fibers, or a combination thereof. The method according to any one of claims 1 to 4.

13. The aforementioned fibrous material includes waste paper, market pulp, paper machine waste paper, recycled fibers, or a combination thereof. The method according to any one of claims 1 to 4.

14. The inorganic filler comprises one or more pigments selected from the group consisting of metal oxides, silicates, carbonates, calcium carbonate, crushed lime, chalk, marble (GCC), precipitated calcium carbonate (PCC), talc, kaolin, bentonite, satin white, calcium sulfate, barium sulfate, and titanium dioxide. The method according to any one of claims 1 to 4.

15. At least a portion of the inorganic filler is prepared as part of the recycled fiber material. The method according to any one of claims 1 to 4.

16. The aforementioned pulp includes one or more paper auxiliaries, which are optionally selected from the group consisting of sizing agents, wetting strengtheners, yield enhancers, drainage aids, dry strength enhancers, fluorescent whitening agents, defoamers, biocides, paper dyes, or combinations thereof. The method according to any one of claims 1 to 4.

17. The ash content of the aforementioned paper is in the range of approximately 0% by weight to approximately 40% by weight. The method according to any one of claims 1 to 4.

18. The aforementioned extruded starch is, The extruded starch is a cationic starch. The aforementioned extruded starch is not cross-linked starch. The solubility of the extruded starch is 40-99% or 40-93%. The molecular weight of the extruded starch is greater than 300,000 Da, greater than 500,000 Da, greater than 2,000,000 Da, or 4,000,000 Da or more. The molecular weight of the extruded starch is 12,000,000 Da or less, or 10,000,000 Da or less, or 8,000,000 Da or less. The weight fraction (WF / dLogM) of the extruded starch at 30,000,000 Da is 0.05 or less. The cumulative weight fraction of the extruded starch with a molecular weight of 1,000,000 Da or less or 100,000 Da or less is 0 to 8% or 0 to 1%. The RVA viscosity of the extruded starch is 15,000 cP or less or 5,000 cP or less. The extruded starch is modified chemically or enzymatically during the extrusion process. Having one or more of the following attributes: The method according to claim 4 or 8.

19. A method for producing a starch-containing product, The process includes a step of processing a starch-containing material in an extruder or other high shear and / or high specific mechanical energy environment, The step of processing the starch-containing material is preferably carried out using a twin-screw extruder, optionally using one or more mixed and / or high-shear sections, and substantially without the use of crosslinking agents. A method characterized by the following:

20. The starch-containing material is chemically or enzymatically modified in the extruder or other high-shear environment, for example, the starch is acid-diluted and / or cationized. The method according to claim 19.

21. The resulting product has a molecular weight (Mw) of 300,000 Da or more, or 500,000 Da or more, 2,000,000 Da or more, or 4,000,000 Da or more, or 5,000,000 Da or more, with an optional maximum of 12,000,000 Da. The method according to claim 19.

22. The resulting product has a molecular weight of 3 × 10 ７ It does not substantially have a fraction greater than Da. The method according to any one of claims 19 to 21.

23. The aforementioned starch-containing material includes natural starch or grain flour. The method according to any one of claims 19 to 21.

24. The aforementioned starch-containing material includes corn starch, for example, waxy corn starch. The method according to any one of claims 19 to 21.

25. The aforementioned starch-containing material includes cereal starch (e.g., corn, wheat, or barley starch), root vegetable or tuber starch (e.g., potato or tapioca starch), or bean starch (e.g., pea or lentil starch), or a combination thereof. The method according to any one of claims 19 to 21.

26. The RVA viscosity of the obtained product is 15,000 cP or less or 5,000 cP or less at a solid content of 20%. The method according to any one of claims 19 to 21.

27. The aforementioned extrusion and other treatments are carried out when the SME of the starch-containing material is 100 Wh / kg or more or 150 Wh / kg or more. The method according to any one of claims 19 to 21.

28. The aforementioned extrusion and other processes are carried out at a maximum barrel temperature of 180°C or lower, or 160°C or lower. The method according to claim 27.

29. A wetting agent, plasticizer, or polyol is added to the extruder. The method according to any one of claims 19 to 21.

30. A starch-containing product having a molecular weight (Mw) exceeding 300,000 Da, a) The solids content is 20% and the RVA viscosity is 15,000 cP or less. b) Not substantially containing a weight fraction exceeding 30,000,000 Da (i.e., 3 × 10) ７ The WF / dLogMW in Da must be 0.05 or less. c) The solubility is in the range of 40-99%. d) The cumulative weight fraction of a molecular weight of 1,000,000 Da or less or 100,000 Da or less is in the range of 0 to 8% or 0 to 1%, and e) The molecular weight is 12,000,000 Da or less. A starch-containing product characterized by comprising one or more of the following.

31. The molecular weight is 4,000,000 Da or more. The product according to claim 30.

32. The RVA viscosity at a solid content of 20% is 15,000 cP or less, or 10,000 cP or less. The product according to claim 30.

33. The mixture further comprises one or more wetting agents, plasticizers, and polyols such as glycerol. The product according to claim 32.

34. The aforementioned product mainly consists of, that is, 80% or more of the dry weight of the aforementioned product, one or more of starch, protein, or other materials present in natural starch or flour, or derivatives thereof, optionally waxycorn starch. The product according to any one of claims 30 to 33.

35. The solubility is in the range of 40-93% or 40-92%. The product according to claim 34.

36. It is cationic, and for example, the bound nitrogen content excluding protein nitrogen is in the range of approximately 0.1 to 1.6% or 0.1 to 0.8%. The product according to claim 35.

37. A method for manufacturing paper, cards and cardboard, A paper stock containing a mixture of paper fibers, inorganic filler, water, and at least one type of extruded starch is drained, and a sheet is formed in the wire section. The steps include: pressing the wet paper sheet in the press section to further remove moisture from the sheet; In the drying section, the final step involves removing moisture through heat treatment to form the product, It has, The pulp, having a fiber concentration in the range of 0.5 g / L to 40 g / L and an inorganic filler concentration in the range of 0 to 20 g / L, contains at least one starch dispersion obtained from the extruded starch. Before the papermaking method, for example, before the first dewatering step begins, the pulp containing the starch dispersion is diluted to a fiber concentration in the range of 0.5 g / L to 15 g / L. Subsequently, the diluted pulp is drained to form a sheet, and the sheet is pressed in the press section until it has a solid content of D(x)% by weight or more. Here, D(x) is D(x)=46+(x-10)×0.3 Calculated by, In the same formula, x is the numerical value (unit weight %) of the inorganic filler content of the product, and D(x) is the minimum solid content (unit weight %) of the sheet after pressing. The extruded starch that provides the aforementioned starch dispersion is obtained by a process in which input starch is mixed with an aqueous solution and mechanical and thermal energy is applied in an extruder by shearing and / or additional heating. A method characterized by the following:

38. The extruded starch is added to the thick or thin pulp in the wet end system of the paper machine. The method according to claim 37.

39. The aqueous solution is water, alcohol, or a mixture thereof. The method according to claim 37.

40. The starch added can be any type from among cationic starch, cross-linked cationic starch, anionic starch, cross-linked anionic starch, nonionic starch, cross-linked nonionic starch, amphoteric starch, and cross-linked amphoteric starch. All of these may or may not undergo other chemical modifications, such as carboxylation, oxidation, hydrolysis, etherification, or esterification. The method according to any one of claims 37 to 39.

41. In the step of mixing the aforementioned starch and aqueous solution to obtain a mixture, an additional plasticizer is added in addition to water. The method according to any one of claims 37 to 39.

42. A reactant containing a cationic or anionic functional group is added to the extruder to react with the starch during the extrusion method. The method according to any one of claims 37 to 39.

43. Add a crosslinking agent to the extruder, and / or The mixture of the aforementioned starch and aqueous solution is added to the extruder before the crosslinking agent has already been added to the mixture. The method according to any one of claims 37 to 39.

44. One or more chemical agents are added to the extruder, and / or Before adding the mixture of the input starch and aqueous solution to the extruder, one or more chemical agents have already been added to the mixture. The method according to any one of claims 37 to 39.

45. A hydroxyl solution is injected into the final stage of the extruder. By dispersing the mixture inside or outside the extruder, a dispersion with a solid content of 20% to 50% by weight is obtained. The hydroxyl solution used in the extrusion method is water, a mixture of water and alcohol, or alcohol. The solid content of the obtained dispersion is 20% to 50% by weight. As an option, the dispersion can be added directly to the paper stock, or added after being diluted with old water first. The method according to any one of claims 37 to 39.

46. A high-viscosity starch molten material is discharged from the outlet of the extruder with a dry content of at least 65% by weight and the remaining moisture content being less than 14% by weight or less than 10% by weight. When the aforementioned high-viscosity material is cooled, it becomes a brittle solid that can be crushed into small pieces using cryogenic grinding in a hammer mill or other similar crushing steps / apparatus. The resulting powder product is characterized by being in a completely amorphous state without any signs of birefringence, and by providing a stable dispersion of starch containing particles with a particle size of 0.2 to 100 μm when mixed with cold water solids at a concentration of 1% by weight. The aforementioned starch powder is dispersed in water and added to the thick and / or thin pulp of the paper machine, and / or added early in the pulp preparation process. Preferably, the starch powder is added directly to the paper stock in a thick and / or thin paper stock state that forms a dispersion with the liquid component of the paper stock. The method according to any one of claims 37 to 39.

47. The solid content of starch in the final pulp composition ranges from 500 g of dry starch per ton of dry paper fiber to 50 g of dry starch per ton of dry paper. The method according to any one of claims 37 to 39.

48. At least a portion of the drying section of the papermaking method consists of a Yankee cylinder type apparatus. The method according to any one of claims 37 to 39.

49. The extruded starch is characterized by an RSS of 92% or less. The method according to any one of claims 37 to 39.

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