JP6924801B2 - How to prepare pregelatinized partially hydrolyzed starch and how to make board - Google Patents

Description

Mutual reference to related applications This application is written in US Patent Application No. 14 / 044,582 filed on October 2, 2013, International PCT Application No. PCT / US2013 / 064776 filed on October 14, 2013, and Claims priority under US Patent Application No. 14 / 494,547 filed on September 23, 2014. All of the above patent applications are incorporated herein by reference in their entirety.

Starch generally contains two types of polysaccharides (amylose and amylopectin) and is classified as a carbohydrate. Some starches are usually pregelatinized by heat means. In general, pregelatinized starch can form dispersions, pastes, or gels with cold water. Pregelatinized starch is generally easy to digest and can be used in a number of ways, including as an additive in various foods (eg in baking, snacks, beverages, sugar confectionery, dairy products, gravy, processed foods, sauces, and meat), and in pharmaceuticals. Has been used.

Another use for pregelatinized starch is in the preparation of gypsum wallboard. In this case, during the manufacture of the board, stucco (ie, calcined gypsum in the form of calcium sulphate hemihydrate and / or calcium sulphate anhydrous gypsum), water, starch and, if necessary, other components are typically added. Is mixed in a pin mixer. This pin mixer is a pin mixer as the term is used in the art. A slurry is formed and one of the skim coats (if present) is discharged from the mixer onto a moving conveyor that carries the already applied cover sheet (often upstream of the mixer). The slurry is spread on paper (with a skim coat optionally contained on the paper). Another cover sheet with or without a skim coat is placed on top of the slurry and, for example, a molded plate or the like is used to form a sandwich structure of the desired thickness.

The mixture is formed and solidified by the reaction of calcined gypsum with water to form hardened (ie rehydrated) gypsum, forming a matrix of crystalline hydrated gypsum (ie calcium sulfate dihydrate). It is the desired hydration of the gypsum that forms the linked crystal matrix of the hardened gypsum, thereby imparting strength to the gypsum structure in the product. Heating (eg, in a furnace) is required to evaporate the remaining free (ie unreacted) water to obtain a dry product.

In many cases, pregelatinized starch increases the water requirements of the process. Moisture must be added to the stucco slurry to supplement the water requirements and provide sufficient fluidity during production. This excess water causes manufacturing inefficiencies such as increased drying times, slower production line speeds, and higher energy costs. The inventors have found that pregelatinized partially hydrolyzed starch requires less water.

The inventors have also found that the technique for preparing pregelatinized partially hydrolyzed starch is not fully satisfactory. The conventional method for preparing such pregelatinized partially hydrolyzed starch is not efficient, the amount produced is small, the production is slow, and the energy cost is high. Therefore, in the art, there is a need for improved methods for producing pregelatinized partially hydrolyzed starch, which requires particularly low water requirements.

This description of the background art has been made by the inventors to aid the reader and should not be considered as a reference to the prior art, or any problem indicated is recognized in the art. It should be understood that it should not be considered as an indication of what is being done. The described principles may alleviate problems inherent in other systems in some aspects and embodiments, but the scope of the invention to be protected is defined by the appended claims. It should be understood that the claimed invention is not defined by its ability to solve any particular problem described herein.

In one aspect, the invention provides a method for making pregelatinized partially hydrolyzed starch, which method is (a) with at least water, non-pregelatinized starch and a weak acid that does not substantially chelate calcium ions. To make a wet starch precursor having a moisture content of about 8% by weight to about 25% by weight; (b) feed the wet starch precursor to an extruder; and (c) this wetness. The starch precursor is pregelatinized and acid-modified with the above extruder at a die temperature of about 150 ° C. (about 300 ° F.) to about 210 ° C. (about 410 ° F.). The present invention also provides starch produced according to this method.

In another aspect, the invention provides a method of making pregelatinized partially hydrolyzed starch, which method (a) mixes at least water, non-pregelatinized starch and a strong acid to about 8 weights. To make a wet starch precursor with a water content of% to about 25% by weight, wherein the strong acid is in an amount of about 0.05% by weight or less of the weight of the starch; b) Feeding the wet starch to the extruder; and (c) the wet starch precursor at a die temperature of about 150 ° C. (about 300 ° F) to about 210 ° C. (about 410 ° F). Includes pregelatinization and acid modification with the above extruders. The present invention also provides starch produced according to this method.

In another aspect, the invention provides a method of making a board, which mixes (a) (i) at least water, non-pregelatinized starch and acid to about 8% by weight to about. By forming a wet starch precursor with a water content of 25% by weight, the above acids are (1) weak acids that do not substantially chelate calcium ions, (2) about 0 by weight of the above starch. Forming selected from the group consisting of 0.05% by weight or less of strong acids, or (3) any combination thereof; (ii) feeding the wet starch precursors described above to the extruder; and ( iii) The wet starch is pregelatinized by pregelatinization and acid modification with the above extruder having a die having a temperature of about 150 ° C. (about 300 ° F) to about 210 ° C. (about 410 ° F). Forming partially hydrolyzed starch; (b) mixing this pregelatinized partially hydrolyzed starch with at least water and stacco to form a slurry; (c) this slurry being mixed with a first cover sheet and a second cover. Placing between the sheets to form a wet assembly; (d) cutting the wet assembly into a board; and (e) drying the board. In some embodiments, the hardened gypsum core has greater compressive strength than the hardened gypsum core made with starch prepared differently. In another aspect, the invention provides a board made according to this method.

FIG. 1 is an amyogram in which viscosity (left y-axis) and temperature (right y-axis) are plotted against time (x-axis). This figure shows a pasting curve of starch extruded at a solid content of 10% by weight and a water content of 16% by weight of the test slurry as described in Example 2. FIG. 2 is an amyogram in which viscosity (left y-axis) and temperature (right y-axis) are plotted against time (x-axis). This figure shows a pasting curve of starch extruded at a solid content of 10% by weight and a water content of 13% by weight of the test slurry as described in Example 2. FIG. 3 is a graph plotting the temperature over time, with 3 wt% alum and 0.05 wt% and 0.0625 wt% retarders, respectively, as described in Example 3. Two slurries containing pregelatinized partially hydrolyzed starch treated with and a third slurry containing conventional pregelatinized corn starch having a viscosity of 773 centipores and an amount of 0.05% by weight retarder. It shows the temperature rise curing (TRS) hydration rate.

Embodiments of the present invention provide a method for making pregelatinized partially hydrolyzed starch. In one aspect, the invention provides a method of preparing a board (eg, gypsum wallboard). The pregelatinized partially hydrolyzed starch produced according to the method of the present invention is a food product (eg, baked food, beverage, sugar confectionery, dairy product, instant pudding, gravy, soup mix, processed food, pie filling, sauce, etc. And in meat), in pharmaceuticals, feeds, adhesives, and colorants, etc., and can be used in a variety of other ways. Such starches, prepared according to some embodiments of the invention, are generally easy to digest, can give the food the desired viscosity, and can maintain most of the functional properties of the original base material. ..

Embodiments of the present invention presuppose, at least in part, the surprising and unexpected finding of pregelatinizing and acid denaturing starch in one step in an extruder. Surprisingly and unexpectedly, pregelatinizing and acid denaturing starch in one step in an extruder has considerable advantages over pregelatinizing and acid denaturing starch in another step. For example, as described herein, the method of the present invention for making pregelatinized partially hydrolyzed starch produces without sacrificing desired properties (eg viscosity, fluidity, solubility in cold water, etc.). Higher quantities, faster production, and lower energy costs.

Furthermore, it has been found that extrusion conditions (eg, high temperature and high pressure) can significantly increase the rate of acid hydrolysis of starch. Surprisingly and unexpectedly, this one-step process allows the use of weak acids such as alum and / or smaller amounts of strong acids for acid denaturation of starch. Both acid forms provide a mechanism by which protons from the acid catalyze the hydrolysis of starch. Conventional acid denaturation processes include purification and neutralization steps. The use of a weak acid (eg, alum) and / or a small amount of a strong acid eliminates the need for a neutralization step followed by a purification step according to some embodiments of the invention. The purification step is required in conventional systems to purify the salt starch produced in the neutralization step.

The extrusion process not only pregelatinizes the starch, but also partially hydrolyzes the starch molecules (ie, by acid denaturation) according to embodiments of the present invention. Therefore, the one-step extrusion process provides both physical modification (pregelatinization) and chemical modification (acid modification, partial acid hydrolysis). Pregelatinization gives the starch the ability to give strength (for example, to final products such as gypsum board). Due to acid modification, starch is advantageously partially hydrolyzed to gain the ability to impart strength to final products such as gypsum board and reduce the amount of water required in product manufacturing, such as in the case of gypsum board manufacturing processes. .. Therefore, the product of the starch preparation method of the embodiment of the present invention is pregelatinized partially hydrolyzed starch.

According to some embodiments, the present invention provides a highly efficient acid denaturation reaction. Extruder pregelatinization and acid denaturation occur at high temperatures and / or high pressures as described herein, resulting in acid hydrolysis rates at lower temperatures (eg 50 ° C.) and / or lower pressures. It can be about 30,000 times greater than conventional acid hydrolysis rates. The rate of acid hydrolysis is further increased by using low water (about 8% to about 25% by weight) levels in the starch precursor, which increases the concentration of the reactants. Due to this highly efficient acid denaturation, surprisingly and unexpectedly, weak acids or very low levels of strong acids can be used in starch precursors to achieve optimum acid denaturation, neutralization and The inventors have found that there is no need for purification. This neutralization and purification is a costly, time consuming and inefficient requirement in conventional systems.

According to some embodiments, hydrolysis is designed to turn starch into small molecules within the optimal size range. The optimum size range is defined herein by the desired viscosity of the pregelatinized partially hydrolyzed starch. When starch is over-hydrolyzed, it is converted into overly small molecules (eg, oligosaccharides or sugars), and as a result, in the case of gypsum board, the board strength provided by pregelatinized partially hydrolyzed starch with the desired viscosity. The board strength can be less than that.

The pregelatinized partially hydrolyzed starch is (i) mixed with at least water, non-pregelatinized starch and acid to form a wet starch precursor with a water content of about 8% to about 25% by weight. Can be prepared by. The above acids are (1) weak acids that do not substantially chelate calcium ions, (2) strong acids in an amount of about 0.05% by weight or less by weight of starch, or (3) any combination thereof. be able to. Wet starch precursors are pregelatinized and acid modified in one step in an extruder at high die temperatures and / or high pressures as described herein. Starch is hydrolyzed to the extent that it has the desired viscosity, for example as described herein.

Thus, in some embodiments, the pregelatinized partially hydrolyzed starch is a mixture of at least water, non-pregelatinized starch and a weak acid that does not substantially chelate calcium ions, from about 8% by weight to about. It can be made by making a wet starch precursor having a water content of 25% by weight. Wet starch is then fed to the extruder. While in an extruder with a die temperature of about 150 ° C (about 300 ° F) to about 210 ° C (about 410 ° F), the wet starch is acid-modified so that it is pregelatinized and at least partially hydrolyzed. Will be done.

In a further embodiment, the pregelatinized partially hydrolyzed starch is a mixture of at least water, non-pregelatinized starch and a strong acid to provide a wet starch precursor having a moisture content of about 8% to about 25% by weight. It can be prepared by making, and the above-mentioned strong acid is in an amount of about 0.05% by weight or less based on the weight of the above-mentioned starch. Wet starch is then fed to the extruder. While in an extruder with a die temperature of about 150 ° C (about 300 ° F) to about 210 ° C (about 410 ° F), the wet starch is acid-modified so that it is pregelatinized and at least partially hydrolyzed. Will be done.

The resulting pregelatinized partially hydrolyzed starch preferably requires less water when incorporated into the stucco slurry and, in some embodiments, has good strength (eg gypsum board). Can be useful in the manufacture of gypsum. Thus, in another aspect, the invention provides a method of making gypsum board using starch prepared using the method of the invention, which is pregelatinized and acid-denatured in one step in an extruder. In some embodiments, the pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention requires less water than other pregelatinized starches known to those of skill in the art.

As a result, the pregelatinized partially hydrolyzed starch prepared according to the embodiments of the present invention (eg, to the pin mixer by the feed line) is incorporated into the stucco slurry with good fluidity. In some embodiments, a larger amount of pregelatinized partially hydrolyzed starch prepared according to the embodiments of the present invention can be incorporated so that higher strength and lower board density can be obtained. .. This is because there is no need to add excess water to the system. The resulting board exhibits good strength properties (eg, good core hardness, nail pull resistance, compressive strength, etc., or relationships between them based on any combination of the values provided herein. matter). Advantageously, by incorporating starch prepared according to the method of the present invention into the production of gypsum board, the strength is increased, which makes it possible to produce ultra-low density products. Gypsum board can be in the form of gypsum wallboard (often referred to as drywall), for example, and this gypsum wallboard is for ceilings and other places as well as for walls, as will be appreciated by those skilled in the art. The board used for gypsum can also be included. However, starch prepared according to this method can also have other uses, such as those used in foods.
Pregelatinization and acid denaturation

Starch is classified as a carbohydrate and contains two types of polysaccharides: straight chain amylose and branched chain amylopectin. Starch granules are semi-crystalline, as seen, for example under polarized light, and are insoluble at room temperature. Gelatinization is the process by which starch is heated in water (“heat treated”) so that the crystal structure of the starch granules melts, and the starch molecules dissolve in water and disperse well. Since starch granules are water insoluble, it has been found that when starch granules change to gelatinized form, they show almost no viscosity in water at an early stage. As the temperature rises, the starch granules swell and the crystal structure melts at the gelatinization temperature. Peak viscosity is obtained when the starch granules swell to the maximum. Further heating breaks the starch granules, the starch molecules dissolve in water, and the viscosity drops sharply. After cooling, the starch molecules reassociate to form a 3-D gel structure, which increases the viscosity. Some commercially available starches are sold in pregelatinized form and others are sold in fine grained form. According to some embodiments of the present invention, with respect to gypsum board, the fine-grained form undergoes at least some degree of gelatinization. By way of example, with respect to gypsum board, starch is pregelatinized before being added to gypsum slurry, also referred to herein as stucco slurry (usually in a mixer such as a pin mixer).

Thus, as used herein, "pregelatinization" means that the starch is gelatinized to any extent, for example before being incorporated into a gypsum slurry, or for use in other applications. means. In some embodiments relating to gypsum board, pregelatinized starch can be partially gelatinized upon incorporation into the slurry, but has been exposed to high temperatures, for example in a furnace during the process of removing excess water. When it is completely gelatinized. In some embodiments relating to gypsum board, if the starch meets the moderate viscosity properties of some embodiments under conditions according to the Viscosity-Modified Mixing (VMA) method, the pregelatinized starch is furnace. It is not completely gelatinized even when it leaves.

When referring to viscosity herein, unless otherwise specified, viscosity is in accordance with the VMA method. According to this method, the viscosity is measured using a Discovery HR-2 hybrid rheometer (TA Instruments Ltd) with concentric cylinders, a standard cup (diameter 30 mm) with a blade shape (diameter 28 mm, length 42.05 mm). ..

Once the starch is obtained, differential scanning calorimetry (DSC) techniques are used to determine if the starch is completely gelatinized. The DSC process can be used to observe whether the starch is completely gelatinized, for example to ensure that no aging has occurred. One of two procedures is applied, depending on the temperature required to completely gelatinize the starch. As will be appreciated by those skilled in the art, the temperature may also be determined by the DSC.

If the DSC reveals that the starch is completely gelatinized or has a gelatinization temperature of 90 ° C. or lower, step 1 is used. If the gelatinization temperature is higher than 90 ° C., step 2 is used. Since the viscosity is measured while the starch is in water, in step 2 the pressure heat treatment in a sealed container is used to heat to a temperature above 100 ° C. without causing obvious water evaporation. As discussed below, step 1 occurs gelatinization in an open rheometer that cannot create pressure conditions for gelatinization, so already fully gelatinized starch or gelatinization below 90 ° C. For starch with temperature. Therefore, step 2 is carried out with starch having a higher gelatinization temperature. In either method, when measuring the viscosity, starch (7.5 g, dry standard) is added to water for a total weight of 50 g.

In step 1, the starch is dispersed in water (starch and 15% of the total weight of water starch) and the sample is immediately transferred to the cylinder cell. Cover the cell with aluminum foil. The sample is heated from 25 ° C. to 90 ° C. at 5 ° C./min at a shear rate of 200s- ^1. The sample is held at 90 ° C. for 10 minutes at a shear rate of 200s- ^1. The sample is cooled from 90 ° C. to 80 ° C. at 5 ° C./min at a shear rate of 200s- ^1. The sample is held at a shear rate of 0s- ¹ at 80 ° C. for 10 minutes. The viscosity of the sample is measured at 80 ° C. and a shear rate of 100 s- ¹ for 2 minutes. Viscosity is the average of measurements from 30 to 60 seconds.

Step 2 is used with starch having a gelatinization temperature higher than 90 ° C. Starch is gelatinized according to methods well known in the starch industry (eg, by pressure heat treatment). Immediately transfer an aqueous solution of gelatinized starch (15% of total weight) into a rheometer measuring cup and keep it in equilibrium at 80 ° C. for 10 minutes. The viscosity of the sample is measured at 80 ° C. and a shear rate of 100 s- ¹ for 2 minutes. Viscosity is the average of measurements from 30 to 60 seconds.

Viscograph and DSC are two different methods of representing starch gelatinization. The degree of starch gelatinization can be determined, for example, from a thermogram from DSC, for example using the peak area (melting of crystals) in the calculation. Viscograms (from Biscograph) are less desirable for determining the degree of partial gelatinization, but for example starch viscosity changes, maximum gelatinization, gelatinization temperature, aging, retention viscosity, cooling termination It is an excellent tool for obtaining data such as viscosity at times. To determine the degree of gelatinization, DSC measurements are performed in the presence of excess water, especially in the presence of excess water of 67% or more by weight. If the moisture content of the starch / water mixture is less than 67%, the gelatinization temperature will increase as the moisture content decreases. Melting starch crystals is difficult when the available water is limited. If the moisture content of the starch / water mixture has reached 67%, the gelatinization temperature will remain constant no matter how much more water is added to the starch / water mixture. The gelatinization start temperature indicates the temperature at which gelatinization starts. The gelatinization end temperature indicates the temperature at which the gelatinization ends. The enthalpy of gelatinization represents the amount of crystal structure melted during gelatinization. The degree of gelatinization can be indicated by using the enthalpy from the starch DSC thermogram.

Different starches have different gelatinization start temperature, end temperature and gelatinization enthalpy. Therefore, different starches may be completely gelatinized at different temperatures. It will be appreciated that starch is completely gelatinized when heated above the gelatinization termination temperature in excess water. Furthermore, for any particular starch, if the starch is heated below the gelatinization end temperature, the starch will be partially gelatinized. Therefore, partial gelatinization and incomplete gelatinization will occur when the starch is heated below the gelatinization end temperature in the presence of excess water, for example as measured by DSC. Complete gelatinization will occur when the starch is heated above the gelatinization end temperature in the presence of excess water, for example as measured by DSC. The degree of gelatinization can be adjusted in different ways, for example by heating starch at a temperature lower than the end of gelatinization temperature to form partial gelatinization. For example, if the enthalpy that completely gelatinizes starch is 4 J / g, then if DSC indicates that the gelatinized enthalpy of starch is only 2 J / g, it means that 50% of the starch is gelatinized. .. Fully gelatinized starch will not have a DSC thermogram gelatinization peak (enthalpy = 0 J / g) as measured by DSC.

As mentioned, the degree of gelatinization can be a suitable arbitrary amount, for example, about 70% or more. However, lower gelatinization results in closer to fine-grained starch, maximizing the advantages of increased strength, better (more complete) dispersion, and / or reduced water requirements in some embodiments of the invention. It may not be available to the limit. Therefore, in some embodiments, a higher degree of gelatinization is preferred, eg, about 75% or more, about 80% or more, about 85% or more, about 90% or more, about 95% or more, about 97%. As mentioned above, it is preferable that the gelatinization is about 99% or more or completely (100%). In the case of gypsum board, starch with a lower degree of gelatinization can be added to the slurry to cause further gelatinization (eg up to 100%) in the furnace. For the purpose of adding to the slurry, "complete gelatinization" means that the starch is sufficiently heat-treated above the gelatinization temperature or the starch is sufficiently heat-treated and is fully gelatinized as can be seen by DSC technology. It will be understood that the transformation is achieved in other ways. Starch may be expected to undergo some slight aging due to cooling, but even so, in some embodiments as will be appreciated by those skilled in the art, in addition to gypsum slurries or in other applications. In the use of, it will be understood as "fully gelatinized". In contrast, such aging is not tolerated in making viscosity measurements with the VMA method discussed herein.

Starch molecules can be acid-denatured to hydrolyze, for example, glycosidic bonds between glucose units to obtain the desired molecular weight. One advantage of acid denaturing starch so that it has a reduced molecular weight would be a reduced water requirement. The water requirements of conventional non-acidified pregelatinized starch are very high and are associated with high energy costs. It has traditionally been considered that denaturation is generally preferred to occur prior to gelatinization, as it tends to be more efficient and cost-effective. However, surprisingly and unexpectedly, the inventors have found that pregelatinization and acid denaturation can be incorporated into one step so that they occur simultaneously rather than sequentially.

Starch Preparation Method According to some embodiments of the present invention, a wet starch precursor is prepared before being placed in an extruder. Wet starch precursors can be prepared by any suitable method. For example, in some embodiments, the wet starch precursor is prepared by combining starch raw materials, water and acid. The acids are (a) a weak acid that does not substantially chelate calcium ions and / or (b) a small amount of a strong acid.

Any suitable starch feedstock can be used as long as the starch feedstock can be used to make pregelatinized partially hydrolyzed starches, such as those that meet the moderate viscosity properties of some embodiments of the invention. Can be selected to prepare a wet starch precursor. As used herein, "starch" refers to a composition containing a starch component. Thus, the starch can be 100% pure starch, or if the starch component constitutes about 75% by weight or more of the starch composition, other components such as proteins and fibers commonly found in flour. It may have an ingredient. Starch can be in the form of starch-containing flour (eg, corn flour), such as about 75% by weight or more of the flour, such as about 80% or more, about 85% or more, about 90% or more, about 95% or more, etc. It can be a flour or the like having the starch of. Any suitable unmodified starch or flour can be used to prepare the pregelatinized partially hydrolyzed starch precursor of the present invention. For example, the starch can be CCM260 yellow cornmeal, CCF600 yellow cornflower (Bunge North America), Clinton 106 (ADM), and / or Midsol 50 (MGP Ingredients).

Wet starch precursors can be prepared to have any suitable moisture content to obtain the desired level of pregelatinization and denaturation on the extruder. In some embodiments, for example, the wet starch precursor preferably has a water content of from about 8% to about 25% by weight, such as from about 8% to about 23% by weight, based on the total weight of the starch precursor. For example, about 8% by weight to about 21% by weight, about 8% by weight to about 20% by weight, about 8% by weight to about 19% by weight, about 8% by weight to about 18% by weight, about 8% by weight to about 17% by weight. , About 8% by weight to about 16% by weight, about 8% by weight to about 15% by weight, about 9% by weight to about 25% by weight, about 9% by weight to about 23% by weight, about 9% by weight to about 21% by weight. , About 9% to about 20% by weight, about 9% to about 19% by weight, about 9% to about 18% by weight, about 9% to about 17% by weight, about 9% to about 16% by weight. , About 9% by weight to about 15% by weight, about 10% by weight to about 25% by weight, about 10% by weight to about 23% by weight, about 10% by weight to about 21% by weight, about 10% by weight to about 20% by weight. , About 10% by weight to about 19% by weight, about 10% by weight to about 18% by weight, about 10% by weight to about 17% by weight, about 10% by weight to about 16% by weight, about 10% by weight to about 15% by weight. , About 11% by weight to about 25% by weight, about 11% by weight to about 23% by weight, about 11% by weight to about 21% by weight, about 11% by weight to about 20% by weight, about 11% by weight to about 19% by weight. , About 11% by weight to about 18% by weight, about 11% by weight to about 17% by weight, about 11% by weight to about 16% by weight, about 11% by weight to about 15% by weight, about 12% by weight to about 25% by weight. , About 12% by weight to about 23% by weight, about 12% by weight to about 21% by weight, about 12% by weight to about 20% by weight, about 12% by weight to about 19% by weight, about 12% by weight to about 18% by weight. , About 12% by weight to about 17% by weight, about 12% by weight to about 16% by weight, about 12% by weight to about 15% by weight, about 13% by weight to about 25% by weight, about 13% by weight to about 23% by weight. , About 13% by weight to about 21% by weight, about 13% by weight to about 20% by weight, about 13% by weight to about 19% by weight, about 13% by weight to about 18% by weight, about 13% by weight to about 17% by weight. , About 13% to about 16% by weight, about 13% to about 15% by weight, about 14% to about 25% by weight, about 14% to about 23% by weight, about 14% to about 21% by weight. , About 14% to about 20% by weight, about 14% to about 19% by weight, about 14% to about 18% by weight, about 14% to about 17% by weight, about 14% to about 16% by weight. , Or about 14% to about 15% by weight, all based on the total weight of the wet starch precursor. During the preparation of wet starch, it will be understood that the moisture content described herein includes the moisture of the surrounding environment and the added water.

We do not want to be bound by any particular theory, but it is believed that low moisture content increases friction in the extruder. In some embodiments, the wet starch is subjected to sufficient mechanical energy as it is fed through the extruder so that friction prevents the wet starch from easily passing through the extruder. It can be prepared to have a water content. Higher friction can increase the breaking of hydrogen bonds in starch.

Any suitable weak acid that does not substantially chelate calcium ions may be mixed with the wet starch. Without wishing to be bound by any particular theory, chelation prevents, for example, the formation of coordination complexes with calcium by weak acids, or otherwise the formation of gypsum crystals in gypsum slurries. Including that. Such hindrance can lead to a decrease in the number of gypsum crystals produced, a delay in crystal formation (decrease in rate), and a decrease in the interaction between gypsum crystals. With respect to not chelating calcium ions, the term "substantially" refers to 90% or more (eg, 92% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99) of available calcium ions. %) Generally means that it does not form a chelate with the acid.

The weak acid of the embodiment of the present invention has a pKa value of about 1 to about 6, for example, about 1 to about 5, about 1 to 4, about 1 to 3, about 1 to 2, about 1.2 to about 6, about 1. .2 to about 5, about 1.2 to about 4, about 1.2 to about 3, about 1.2 to about 2, about 2 to about 6, about 2 to about 5, about 2 to about 4, about 2 It can be defined as having a pKa value of ~ about 3, about 3 ~ about 6, about 3 ~ about 5, about 3 ~ about 4, about 4 ~ about 6, or about 4 ~ about 5. As will be appreciated by those skilled in the art, the pKa value is a measure of the strength of the acid; the lower the pKa value, the stronger the acid.

Weak acids that do not substantially chelate calcium ions are characterized by the absence of multiple binding sites, such as multiple carboxyl functional groups (COO-) that tend to bind to calcium ions. In some embodiments, gypsum crystallization is substantially affected, for example, so that chelation is minimal (ie, substantially nonexistent) or compared to gypsum crystallization in the absence of a weak acid. Weak acids have minimal amounts of multiple binding sites, such as multiple -COO-groups, or are substantially free of multiple binding sites, such as multiple -COO-groups. In some embodiments, for example, aluminum sulphate (alm) is a weak acid suitable for use in the preparation of wet starch, as it does not substantially chelate calcium ions. Alum does not have multiple binding sites.

In some embodiments, the alum is added to the wet starch precursor in any suitable form, for example as an alum-containing liquid with the desired solid content. For example, liquid alum can be contained in an aqueous solution in which alum is present in a suitable arbitrary amount. Other weak acids can be added in the same way.

Weak acids are preferably weak acids that do not substantially chelate calcium ions so that pregelatinized partially hydrolyzed starch is prepared with the desired viscosity and low water requirements and is not overhydrolyzed to sugars. It can be mixed to contain any amount. For example, in some embodiments, such weak acids are included in an amount of about 0.5% to about 5% by weight based on the weight of the starch, eg, about 0.5% to about 4.5% by weight. %%, For example, about 0.5% to about 4% by weight, about 0.5% to about 3.5% by weight, about 0.5% to about 3% by weight, about 1% to about 5% by weight. %, Approximately 1% by weight to approximately 4.5% by weight, approximately 1% by weight to approximately 4% by weight, approximately 1% by weight to approximately 3.5% by weight, approximately 1% by weight to approximately 3% by weight, approximately 1.5% by weight. About 5% by weight, about 1.5% by weight to about 4.5% by weight, about 1.5% by weight to about 4% by weight, about 1.5% by weight to about 3.5% by weight, about 1 .5% to about 3% by weight, about 2% to about 5% by weight, about 2% to about 4.5% by weight, about 2% to about 4% by weight, about 2% to about 3. 5% by weight, about 2% by weight to about 3% by weight, about 2.5% by weight to about 5% by weight, about 2.5% by weight to about 4.5% by weight, about 2.5% by weight to about 4% by weight %, About 2.5% to about 3.5% by weight, or about 2.5% to about 3% by weight. It will be appreciated that these amounts include the weak acid component and, if the acid is a solution, no water or other components of the solution.

The wet starch precursor can optionally be prepared to further include a second acid capable of chelating calcium ions such as tartaric acid. Thus, in some embodiments, a second acid, such as tartaric acid, can be combined with any suitable weak acid that does not chelate calcium ions. Tartaric acid is known to delay gypsum crystallization. However, tartaric acid does not substantially delay gypsum crystallization when combined with a non-chelating weak acid so that the hydrolysis reaction due to acid denaturation is optimized. In addition to tartaric acid, other second acids such as succinic acid or malic acid may be advantageous as long as they do not exceed the accelerating effect of alum. In some embodiments, the wet starch precursor comprises both alum and tartaric acid.

The second acid (eg, tartaric acid), if included, can be present in any suitable amount. For example, tartaric acid can be present in an amount of about 0.1% to about 0.6% by weight based on the weight of starch, for example from about 0.1% to about 0.4% by weight, about 0. It can be present in an amount of 2% to about 0.3% by weight.

In some embodiments, oil can optionally be added to the wet starch to improve starch transportability within the extruder. In some embodiments, possible oils include canola oil, vegetable oil, corn oil, soybean oil, or any combination thereof. For example, in some embodiments, canola oil or one of the aforementioned alternatives can optionally be added in an amount of from about 0% to about 0.25% by weight of starch, eg about 0. .1% by weight to about 0.2% by weight, about 0.1% by weight to about 0.15% by weight, about 0.15% by weight to about 0.25% by weight, about 0.15% by weight to about 0. It can be added in an amount of 2% by weight, or about 0.2% by weight to about 0.25% by weight.

According to some embodiments, the wet starch precursor is prepared by mixing water, non-pregelatinized starch and a small amount of strong acid. In some embodiments, the strong acid has a pKa of about -1.7 or less. Any such acid can be used and in some embodiments the strong acid comprises sulfuric acid, nitric acid, hydrochloric acid, or any combination thereof. Sulfate ions can accelerate gypsum crystallization in gypsum board embodiments, so in some embodiments, sulfuric acid alone or a combination of sulfuric acid and other acids is preferred.

The amount of strong acid is relatively small, for example about 0.05% by weight or less of the weight of starch, for example about 0.045% by weight or less, about 0.04% by weight or less, about 0.035% by weight or less, about 0. .03% by weight or less, about 0.025% by weight or less, about 0.02% by weight or less, about 0.015% by weight or less, about 0.01% by weight or less, about 0.005% by weight or less, about 0.001 By weight or less, about 0.0005% by weight or less, for example, about 0.0001% by weight to about 0.05% by weight, about 0.0001% by weight to about 0.045% by weight, about 0. 0001% by weight to about 0.04% by weight, about 0.0001% by weight to about 0.035% by weight, about 0.0001% by weight to about 0.03% by weight, about 0.0001% by weight to about 0.025. Weight%, about 0.0001% to about 0.02% by weight, about 0.0001% to about 0.015% by weight, about 0.0001% to about 0.01% by weight, about 0.0001 weight % To about 0.005% by weight, about 0.0001% to about 0.001% by weight, about 0.0001% to about 0.0005% by weight. It will be appreciated that these amounts include the strong acid component and, if the strong acid is a solution, do not contain water or other components of the solution. For example, conventional strong acid denaturation uses a 2% sulfuric acid solution with ~ 35% starch solid (2 g sulfuric acid for 35 g starch). The percentage is based on the pure sulfuric acid component. It is calculated as the weight of the sulfuric acid component divided by the weight of the wet starch. For example, if the sulfuric acid is 50% pure (meaning that half the weight of the solution is pure sulfuric acid), the weight of the sulfuric acid solution is double. To explain, to make 0.1% by weight, 0.1 g of pure sulfuric acid is added to 100 g of starch. When the sulfuric acid solution concentration is 50%, 0.2 g of 50% sulfuric acid solution is added to make 0.1% by weight.

It will be appreciated that acids have different grades (> 95%, 98%, 99.99%). These differences are embraced by the term "about" with respect to the amount of strong acid in the starch precursor. One of ordinary skill in the art will be able to readily determine the% by weight described herein to include different grades. The amount of strong acid used according to some embodiments of the present invention is significantly less than the amount of strong acid contained in the conventional system, in which in the conventional system, for example, about 2 g or more of sulfuric acid is added to 35 g of starch. used. In some embodiments, a small amount of strong acid as described above can be used in combination with a weak acid that does not chelate calcium ions, such as alum, as described herein.

Embodiments of the present invention provide the wet starch precursor to be fed through the extruder such that the wet starch precursor is pregelatinized and acid-denatured in one step in the extruder. It will be understood that an extruder is a machine generally used to melt and process a polymer into a desired shape by melting the polymer and extruding it through a die. The extruder can also mix the polymer with other ingredients such as dyes, reinforcing fibers, mineral fillers and the like. The purpose of the extruder is to disperse and distribute all the components supplied to the extruder, and to melt the components at a constant temperature and pressure.

The configuration and arrangement of the extruder is known to those skilled in the art. Extruders typically include a feed hopper for feeding feed material, a preconditioner with a heating jacket to condition the plasticizer (eg water) and polymer, an extruder module head with a heating range, and a die assembly. To be equipped. Extruders generally include a feed auger, a knife, and a screw (s). The feed auger is present to assist in transporting the wet starch precursor to the extruder. Knives are present to cut the string-like pregelatinized partially hydrolyzed starch into small pellets so that the pregelatinized partially hydrolyzed starch can be ground. The screw assists in mixing the wet starch precursor, transports the wet starch precursor through the extruder, and provides mechanical shear. The extruder can be a single-screw or twin-screw type extruder, as will be appreciated by those skilled in the art. Lessek Mosicki, Extension-Cooking Technologies, WILEY-VCH Verlag & Co., Ltd. See KGaA, 2011.

In single-screw screw extruders, the screw generally has a deep groove, a supply section that carries solids from the mouth of the feeder and compresses them, a compression section where the groove of the screw becomes shallower and the polymer melts, and a shallow groove. And with a weighing unit that carries the molten polymer to the die. Some screws are designed to include a mixer (eg, a pin extending from the screw).

Biaxial screw extruders generally have two screws, both of which rotate in the same direction (ie, co-rotate) or in opposite directions (ie, counter-rotate). The two screws may rotate with a non-meshing screw type or with a fully meshing screw type. In the case of a single-screw extruder, the material being supplied fills the entire screw groove, but in the case of a twin-screw extruder, a downstream supply port or supply hole can be used to add a particular component. As you can see, only a part of the screw groove is filled.

Die assemblies generally include a plate, spacers, and a die head. When extruding the material, the process can be either continuous, in which the material is extruded to an infinite length, or semi-continuous, in which the material is extruded to a specific length. The extruded material may be hot or cold.

The present invention provides a method for preparing pregelatinized partially hydrolyzed starch in an extruder. Any suitable extruder can be used, such as a single-screw extruder (eg, Advance 50 available from American Extension International in South Beloit, Illinois), or a twin-screw screw extruder (eg, Sabetha, Kansas). Wenger TX52) and the like, which can be obtained from a certain Wenger.

As described herein, water is mixed with non-pregelatinized starch, an acid in the form of a weak acid and / or a small amount of strong acid that does not substantially chelate calcium ions, and fed to the extruder. In some embodiments, additional water may be added to the extruder. In the extruder, the weak acid partially hydrolyzes the starch to the desired molecular weight while the starch is melted and pregelatinized in combination with a heating element and mechanical shear. Its molecular weight is indicated by the desired viscosity as described herein. Depending on the conditions in the extruder, mechanical energy also causes deterioration of starch molecules, which partially has the same effect as acid denaturation. It is believed that weak acids and / or small amounts of strong acids can be used because the conditions in the extruder of some embodiments (eg, high reaction temperature and high pressure) facilitate this chemical reaction. Therefore, the method of the present invention improves the efficiency of starch acid denaturation.

The main screw (s) can be operated at any suitable speed to obtain the desired mixing and mechanical shear. For example, in some embodiments, the main screw can be operated at a speed of about 350 RPM (± about 100 RPM). The feed auger can be operated at any suitable speed to obtain the desired feed rate. For example, in some embodiments, the feed auger can be operated at a speed of about 14 RPM (± about 5 RPM).

The knife can be operated at any suitable speed. For example, in various embodiments, the knife can be operated at speeds of about 400 RPM to about 1,000 RPM, eg, about 400 RPM to about 900 RPM, about 400 RPM to about 800 RPM, about 400 RPM to about 700 RPM, about 400 RPM to about 600 RPM, About 400 RPM to about 500 RPM, about 500 RPM to about 1,000 RPM, about 500 RPM to about 900 RPM, about 500 RPM to about 800 RPM, about 500 RPM to about 700 RPM, about 500 RPM to about 600 RPM, about 600 RPM to about 1,000 RPM, about 600 RPM to about 900 RPM, about 600 RPM to about 800 RPM, about 600 RPM to about 700 RPM, about 700 RPM to about 1,000 RPM, about 700 RPM to about 900 RPM, about 700 RPM to about 800 RPM, about 800 RPM to about 1,000 RPM, about 800 RPM to about 900 RPM, or about It can be operated at speeds of 900 RPM to about 1,000 RPM.

Wet starch can be pregelatinized and acid modified in an extruder with a die at a suitable arbitrary temperature such that the wet starch is sufficiently pregelatinized without carbonizing the material. Wet starch, for example, can be pregelatinized and acid-denatured in an extruder with a die having a temperature of about 150 ° C. (about 300 ° F.) to about 210 ° C. (about 410 ° F.), eg, in various embodiments. , About 150 ° C to about 205 ° C (about 400 ° F), about 150 ° C to about 199 ° C (about 390 ° F), about 150 ° C to about 193 ° C (about 380 ° F), about 150 ° C to about 188 ° C. (About 370 ° F), about 150 ° C to about 182 ° C (about 360 ° F), about 154 ° C (about 310 ° F) to about 210 ° C, about 154 ° C to about 205 ° C (about 400 ° F), about 154 ° C to about 199 ° C, about 154 ° C to about 193 ° C, about 154 ° C to about 188 ° C, about 154 ° C to about 182 ° C, about 160 ° C (about 320 ° F) to about 210 ° C, about 160 ° C to about 205 ° C (about 400 ° F), about 160 ° C to about 199 ° C, about 160 ° C to about 193 ° C, about 160 ° C to about 188 ° C, about 160 ° C to about 182 ° C, about 166 ° C (about 330 ° F) ~ 210 ° C, about 166 ° C to about 205 ° C, about 166 ° C to about 199 ° C, about 166 ° C to about 193 ° C, about 166 ° C to about 188 ° C, about 166 ° C to about 182 ° C, about 171 ° C (about 171 ° C) 340 ° F) to about 210 ° C, about 171 ° C to about 205 ° C, about 171 ° C to about 199 ° C, about 171 ° C to about 193 ° C, about 171 ° C to about 188 ° C, about 171 ° C to about 182 ° C, about. 177 ° C (about 350 ° F) to about 210 ° C, about 177 ° C to about 205 ° C, about 177 ° C to about 199 ° C, about 177 ° C to about 193 ° C, about 177 ° C to about 188 ° C, or about 177 ° C to It can be pregelatinized and acid-denatured in an extruder with a temperature die of about 182 ° C. The die of the extruder can be at any sufficient temperature as described herein, but the die temperature generally exceeds the melting temperature of the starch crystals.

The degree of gelatinization can be any suitable amount, for example about 70% or more, for example about 75% or more, about 80% or more, about 85% or more, about 90% or more, about 95% or more, about 97%. As mentioned above, it can be about 99% or more or complete (100%) gelatinization. In the case of making wallboards as described below, starch with such a lower degree of gelatinization is added to the stucco slurry to cause, for example, further gelatinization (eg up to 100%) in the furnace. Can be done.

The pressure in the extruder can be at any suitable level that provides suitable conditions for pregelatinization and acid denaturation. The pressure inside the extruder will be determined by the raw material being extruded, the moisture content, the die temperature and the screw speed and will be recognized by those skilled in the art. For example, the pressure in the extruder can be about 2,000 psi (about 13,800 kPa) or more, for example about 2,250 psi (about 15,500 kPa) or more, about 2,500 psi (about 17,200 kPa) or more, about. 2,750 psi (about 19,000 kPa) or more, about 3,000 psi (about 20,650 kPa) or more, about 3,500 psi (about 24,100 kPa) or more, about 4,000 psi (about 27,600 kPa) or more, or about 4 , 500 psi (about 31,000 kPa) or more. In some embodiments, the pressure can be from about 2,000 psi to about 5,000 psi (34,500 kPa), eg, from about 2,000 psi to about 4,500 psi, from about 2,000 psi to about 4, 000 psi, about 2,000 psi to about 3,500 psi, about 2,000 psi to about 3,000 psi, about 2,000 psi to about 2,500 psi, about 2,500 psi to about 5,000 psi, about 2,500 psi to about 4, 500 psi, about 2,500 psi to about 4,000 psi, about 2,500 psi to about 3,500 psi, about 2,500 psi to about 3,000 psi, about 3,000 psi to about 5,000 psi, about 3,000 psi to about 4, 500 psi, about 3,000 psi to about 4,000 psi, about 3,000 psi to about 3,500 psi, about 3,500 psi to about 5,000 psi, about 4,000 psi to about 5,000 psi, about 4,000 psi to about 4, It can be 500 psi, or about 4,500 psi to about 5,000 psi.

Surprisingly and unexpectedly, the method of the present invention for preparing pregelatinized partially hydrolyzed starch in one step in an extruder can be significantly faster than pregelatinizing and partially hydrolyzing starch in two consecutive steps. Has been found. By using the present invention, it is possible to prepare a significantly larger amount of pregelatinized partially hydrolyzed starch than starch prepared using any other method. The higher production and faster production rates are due to the high reaction rates at high temperatures and / or high pressures. In some embodiments, pregelatinization and acid denaturation occur in less than about 5 minutes, eg less than about 4 minutes, such as less than about 3 minutes, less than about 2 minutes, less than about 90 seconds, less than about 75 seconds, about. It occurs in less than 1 minute, less than about 45 seconds, less than about 30 seconds, less than about 25 seconds, less than about 20 seconds, less than about 15 seconds, or less than about 10 seconds. Moreover, in some embodiments, pregelatinization and acid denaturation occur in the extruder at a rate limited by any two of the aforementioned time points. For example, the pregelatinization and acid denaturation rate can be from about 10 seconds to 5 minutes, for example about 10 seconds to about 4 minutes, about 10 seconds to about 3 minutes, about 10 seconds to about 2 minutes, about 10 seconds to about. 90 seconds, about 10 seconds to about 75 seconds, about 10 seconds to about 1 minute, about 10 seconds to about 45 seconds, about 10 seconds to about 30 seconds, about 10 seconds to about 25 seconds, about 10 seconds to about 20 seconds , Or it can be from about 10 seconds to about 15 seconds.

The method of the present invention for preparing pregelatinized partially hydrolyzed starch can be a continuous process that occurs at any sufficient rate. In some embodiments, the starch is pregelatinized and acid-denatured in an extruder at a production rate of about 100 kg / hour or more, eg, about 150 kg / hour or more, about 200 kg / hour or more, about 250 kg / hour or more. , About 300 kg / hour or more, about 350 kg / hour or more, about 400 kg / hour or more, about 450 kg / hour or more, 500 kg / hour, about 550 kg / hour or more, for example, about 600 kg / hour or more, about 650 kg / hour or more, about 700 kg / Hour or more, about 750 kg / hour or more, about 800 kg / hour or more, about 850 kg / hour or more, about 900 kg / hour or more, about 950 kg / hour or more, about 1,000 kg / hour or more, about 1,050 kg / hour or more, About 1,100 kg / hour or more, about 1,150 kg / hour or more, about 1,200 kg / hour or more, about 1,250 kg / hour or more, about 1,300 kg / hour or more, about 1,350 kg / hour or more, about 1 , 400 kg / hour or more, about 1,450 kg / hour or more, or about 1,500 kg / hour or more at a production rate of pregelatinization and acid denaturation. Moreover, in some embodiments, the production rate can be limited by any two of the speed points described above. For example, the production rate is about 100 kg / hour to about 1,500 kg / hour (for example, about 100 kg / hour to about 1,500 kg / hour, about 100 kg / hour to about 1,000 kg / hour, about 250 kg / hour to about 1). , 500 kg / hour, about 250 kg / hour to about 1,000 kg / hour, about 600 kg / hour to about 1,250 kg / hour, about 650 kg / hour to about 1,200 kg / hour, about 700 kg / hour to about 1,100 kg / Hour, about 750 kg / hour to about 1,000 kg / hour, etc.).

In some embodiments, the inventors have found that conditions within the extruder (eg, high temperature and high pressure) particularly contribute to the efficient and sufficient pregelatinization and acid denaturation of starch in one step. .. Mixing wet starch in an extruder creates a very large amount of friction, which produces heat. Since the space between the screw and the chamber in the extruder is very small, the screw creates a shear force in the extruder. Specific mechanical energy (SME) represents mechanical energy per unit of mass of an object. SME will depend on the water content. The higher the water content (eg, due to fluidity), the lower the viscosity and friction, and therefore the SME. In the presence of more water, the viscosity and friction will be smaller and the SME will be smaller. The water content in the wet starch precursors of the invention described herein provides an efficient SME.

In the extruder, starch is pregelatinized with high efficiency due to the conditions provided by the embodiments of the invention described herein. Although not bound by any particular theory, good mixing in an extruder according to some embodiments of the invention requires water for the reaction in the extruder. Is considered to be a smaller amount. Since the water content is very low, the reaction product concentration tends to be high, and the chemical reaction rate can be accelerated. The high temperature of the extruder also significantly accelerates the reaction rate. When the starch exits the extruder, the reaction takes place so that the starch is pregelatinized and partially hydrolyzed.

In conventional acid denaturation, starch is added to a strong acid solution. This conventional method is significantly more water than the surprising and unexpected method of simultaneously pregelatinizing and acidifying starch in one step rather than continuously, as described herein. And use acid. Conventional acid denaturation takes several hours. After the reaction takes place, it is necessary to neutralize the acid, purify and wash away. The neutralization and purification steps are time consuming and costly.

Until the surprising and unexpected discovery of the inventors, it was considered undesirable in conventional acid denaturation to use a weak acid that does not substantially chelate calcium ions, or a small amount of a strong acid. This is because, in the conventional method, when the acid becomes weak or the amount of the strong acid becomes small, the acid denaturation takes a long time. Therefore, in conventional acid denaturation, large amounts of strong acids (eg, having a pKa of less than about -1.7) have been shown. Surprisingly and unexpectedly, when preparing pregelatinized partially hydrolyzed starch in an extruder using the weak acids or small amounts of strong acids described herein according to embodiments of the invention, the neutralization step and There is no need for a purification process. This is due to the mild acidic conditions and less interference with gypsum crystallization. In some embodiments, the acid can still be present in the pregelatinized partially hydrolyzed starch.

Characteristics of Starch and Advantages of Using Starch in Gypsum Board The starch prepared by the extruder according to the embodiment of the present invention can be any pregelatinized partially hydrolyzed starch. In some embodiments, the starch can be prepared to have a variety of desired properties as described herein (eg, medium viscosity, cold water solubility, cold water viscosity, etc.).

The pregelatinized partially hydrolyzed starch prepared by an extruder according to an embodiment of the present invention can be suitable for use in gypsum board. For use in gypsum board, for example, pregelatinization and acid denaturation are advantageous, for example for strength purposes, by obtaining the desired viscosity (and therefore the molecular weight range) according to the embodiments of the invention described herein. be. In the method of making wallboards discussed herein, the starch contained in the stucco slurry can be gelatinized by about 70% or more, for example about 75% or more gelatinization, about 80% or more gelatinization, about. It can be 85% or more gelatinized, about 90% or more gelatinized, about 95% or more gelatinized, about 97% or more gelatinized, or about 100% gelatinized (ie, completely gelatinized).

Further, according to an embodiment of the present invention, the desired viscosity can be obtained by supplying the extruder with a wet starch containing a weak acid that does not substantially chelate calcium ions as described herein. The starch is hydrolyzed to show that the desired molecular weight range has been obtained. Therefore, as will be appreciated by those skilled in the art, viscosity indicates the molecular weight of pregelatinized partially hydrolyzed starch.

In some embodiments, the pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention can be prepared to have any suitable viscosity. In some embodiments, the pregelatinized partially hydrolyzed starch is a condition of the VMA method when the pregelatinized partially hydrolyzed starch is in water in an amount of 15% by weight of the total weight of the pregelatinized partially hydrolyzed starch and water. When attached to, the viscosity is characterized as having a "moderate" viscosity (ie, having a viscosity of about 20 centipoise to about 700 cmpoise). Therefore, the VMA method is used to determine if pregelatinized partially hydrolyzed starch exhibits moderate viscous properties when subject to the conditions of the VMA method. This does not mean that pregelatinized partially hydrolyzed starch must be added to the gypsum slurry under these conditions. Rather, when adding pregelatinized partially hydrolyzed starch to the slurry, the starch can be in wet form (various concentrations of starch in water) or in dry form, and as described herein, completely. It does not have to be gelatinized, or otherwise it does not need to be under the conditions described in the VMA method.

In some embodiments, the moderate viscosity of pregelatinized starch can be from about 20 centimeters to about 700 centimeters, eg from about 20 centimeters to about 500 centimeters, from about 30 centimeters to about 200 centimeters, or about. It can range from 100 centimeters to about 700 centimeters. In embodiments of the invention, the viscosities of pregelatinized starch when tested under the VMA method can be, for example, as listed in Tables 1A, 1B and 1C below. In the table, "X" represents the range from about [corresponding value in the top row] to about [corresponding value in the leftmost column]. The values shown represent the viscosity of pregelatinized starch in centipores. For ease of representation, it will be understood that each value is represented by "about". For example, the first "X" in Table 1A ranges from "about 20 centimeters to about 25 centimeters".

Therefore, the viscosity of the pregelatinized partially hydrolyzed starch prepared according to the embodiments of the present invention can have a range including between or any of the aforementioned endpoints listed in Tables 1A, 1B or 1C. Alternatively, in some embodiments, the pregelatinized partially hydrolyzed starch has a viscosity (10% solid, 93) of about 5 lavender units (BU) to about 33 BU as measured according to the lavender method described herein. ℃), and has a viscosity of, for example, about 10 BU to about 30 BU, about 12 BU to about 25 BU, or about 15 BU to about 20 BU.

In some embodiments, the pregelatinized partially hydrolyzed starch prepared according to the embodiments of the present invention provides an advantageous advantage to the strength of the product (eg, wallboard) in which the pregelatinized partially hydrolyzed starch is used. be able to. Since starch contains a glucose monomer containing three hydroxyl groups, it provides multiple sites for hydrogen bonding to gypsum crystals. Without wishing to be bound by any particular theory, the molecular size of pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention provides optimal starch molecule mobility and starch molecules. Is believed to align with the gypsum crystals, promote good bonding of starch molecules and gypsum crystals, and strengthen the resulting crystalline gypsum matrix, for example by hydrogen bonds.

Conventional pregelatinized starches prepared according to methods other than those described herein, eg, having a non-medium viscosity, have longer chain lengths and higher molecular weights (too high viscosities) and shorter chain lengths. And have either low molecular weight (too low viscosity) and do not provide the same combination of advantages, respectively. With respect to starch efficiency, if the gypsum molecules are sufficiently attached to the gypsum crystals, the additional gypsum has a significant advantage because the gypsum crystals are already attached so that there are no additional gypsum crystal sites to which the starch molecules adhere or bind. It is also thought that it will not last. Therefore, the optimum binding between the pregelatinized partially hydrolyzed starch molecule and the gypsum crystal prepared according to the embodiment of the present invention improves the strength of the crystalline gypsum matrix, and the starch required to increase this strength has been conventionally used. Less than starch. In some embodiments, for example, dissolved starch molecules with moderate viscosity (indicating a moderate starch molecular weight) provide optimal mobility of the starch molecules so that the starch molecules are aligned with the gypsum crystals. The inventors have found that good hydrogen bonding between starch molecules and gypsum crystals is promoted and core strength is promoted.

The pregelatinized partially hydrolyzed starch prepared according to some embodiments of the present invention also provides an advantage in terms of water requirements in some embodiments. Adding conventional pregelatinized starch to the gypsum slurry requires the addition of additional water to the gypsum slurry to maintain the desired degree of slurry fluidity. This is because conventional pregelatinized starch increases the viscosity of the gypsum slurry and reduces its fluidity. Therefore, the use of starch in conventional systems has resulted in an increase in water requirements such that more excess water is required in the gypsum slurry.

Surprisingly and unexpectedly, pregelatinized partially hydrolyzed starches prepared according to embodiments of the present invention, in particular having the desired moderate viscosity, require less water and are particularly compared to conventional starches. Therefore, the effect on the water requirement of the gypsum slurry is reduced. Furthermore, due to the efficiency of pregelatinized partially hydrolyzed starch prepared according to embodiments of the invention, such that less starch can be used, to water requirements according to some embodiments of the invention. The favorable effects can be even more significant. This lower water requirement provides considerable efficiency during production. Excess water, for example, requires energy input to dry. The speed of the line must be slowed down to accommodate drying. Therefore, reducing the amount of water input into the gypsum slurry not only increases the production rate, but also reduces energy resources and costs. In some embodiments, the increment of water requirement in the gypsum slurry is required by other starches, such as pregelatinized starches having viscosities greater than 700 centipoise (eg, about 773 cmpoise), prepared by different methods, for example. Less than the alleged increment of water requirements.

In the preparation of pregelatinized partially hydrolyzed starch, any suitable non-pregelatinized starch can be selected as long as it is sufficiently pregelatinized and acid-denatured in the extruder. As used herein, "starch" refers to a composition containing a starch component. Thus, the starch can be 100% pure starch, or if the starch component constitutes about 75% by weight or more of the starch composition, other components such as proteins and fibers commonly found in flour. It may have an ingredient. Starch can be in the form of starch-containing flour (eg, corn flour), such as about 75% by weight or more of the flour, such as about 80% or more, about 85% or more, about 90% or more, about 95% or more, etc. It can be a flour or the like having the starch of. For example, but not limited to, starch can be in the form of starch-containing cornflower.

In some embodiments, the pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention can be prepared to have the desired cold water solubility. Conventional pregelatinization techniques include making starch soluble in cold water and generally require heat treatment of starch in excess water. However, these prior arts are not efficient. Extrusion involves a combination of heating and mechanical shear, but surprisingly and unexpectedly, according to embodiments of the present invention, pregelatinized partially hydrolyzed starch with low water content and cold water solubility is produced in a one-step process. It is an energy efficient method that can be used to do so. Cold water solubility is defined as having an arbitrary amount of solubility in water at room temperature (about 25 ° C.). It has been discovered that starch, which exhibits solubility in cold water, can provide a significant advantage to the strength of gypsum products (eg, wallboards). The cold water-soluble starch of the present invention has a cold water solubility of greater than about 30% and can increase the strength of the gypsum core when added to the hardened gypsum core. The solubility of pregelatinized starch in water is defined as the amount of starch dissolved in water at room temperature divided by the total amount of starch.

In some embodiments, the cold water solubility of pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention is from about 30% to about 100%. In other embodiments, the cold water solubility of the extruded pregelatinized partially hydrolyzed starch is from about 50% to about 100%. In embodiments of the present invention, the cold water solubility of the extruded pregelatinized partially hydrolyzed starch can be, for example, as listed in Table 2. In the table, "X" represents the range from about [corresponding value in the top row] to about [corresponding value in the leftmost column]. The values shown represent the cold water solubility of extruded pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention (Table 2). For ease of representation, it will be understood that each value is represented by "about". For example, the first "X" in Table 2 is in the range of "about 30% to about 35%". The range of the table is between the start point and the end point and includes the start point and the end point.

Without wishing to be bound by any particular theory, the combination of mechanical and thermal energy during extrusion is the cold water solubility of pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention. Probably the cause. As the starch undergoes extrusion, the hydrogen bonds between the starch molecules are thought to break. When the extruded starch dissolves in water, the starch forms hydrogen bonds with water molecules. After the pregelatinization process, the extruded pregelatinized partially hydrolyzed starch is free to hydrogen bond with the gypsum crystals, thus giving the gypsum product higher strength. Therefore, starch that is soluble in cold water improves the strength of gypsum wallboard and therefore requires less starch compared to conventional starch.

In some embodiments, the pregelatinized partially hydrolyzed starch has a cold water viscosity (10% solid, 25 ° C.) of about 10 BU to about 120 BU as measured according to the lavender method described herein. For example, it has a viscosity of about 20 BU to about 110 BU, about 30 BU to about 100 BU, about 40 BU to about 90 BU, about 50 BU to about 80 BU, or about 60 BU to about 70 BU.

Use of Starch Prepared According to Methods in Board Making In some embodiments, the board (eg, gypsum board) is a mixture of at least water, non-pregelatinized starch and acid, from about 8% by weight to about. It can be made by forming pregelatinized partially hydrolyzed starch by making a wet starch precursor with a water content of 25% by weight, the above acids are: weak acids, starches that do not substantially chelate calcium ions. It is selected from strong acids in an amount of about 0.01% by weight or less, or a combination thereof.

The wet starch precursor is then fed to an extruder with a die temperature of about 150 ° C (about 300 ° F) to about 210 ° C (about 410 ° F) to pregelatinize the wet starch and at least partially hydrolyze it. Acid denaturation. The pregelatinized partially hydrolyzed starch is then mixed with at least water and stucco to form a slurry, which is then placed between the first cover sheet and the second cover sheet to form a wet assembly. The wet assembly is then cut into boards and dried. The hardened gypsum core of the board preferably has a higher compressive strength than the hardened gypsum core made using starch prepared by different methods.

The pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention can, surprisingly and unexpectedly, be contained in the slurry in relatively small amounts (solid / solid basis) and still on the board. A significant improvement in strength can be obtained. Therefore, the pregelatinized partially hydrolyzed starch prepared according to the embodiment of the present invention is in an amount of about 0.1% by weight to about 10% by weight, for example, about 0.5% by weight to about 10% by weight, based on the weight of stucco. Can be contained in gypsum slurry.

Increasing the amount of pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention beyond these ranges in the slurry does not effectively improve strength. This is because, in some embodiments, the strength level can reach a certain level with respect to the addition of more starch. However, higher starch amounts can be used where necessary, especially where diminishing returns in strength are tolerated.

In embodiments of the present invention, pregelatinized partially hydrolyzed starch can be added to the gypsum slurry in amounts such as those listed in Tables 3A and 3B below. In the table, "X" represents the range from about [corresponding value in the top row] to about [corresponding value in the leftmost column]. The values shown represent the amount of starch as a weight percent of stucco. For ease of representation, it will be understood that each value is represented by "about". For example, the first "X" ranges from "about 0.1% by weight starch of stucco to about 0.25% by weight starch of stucco".

Therefore, the amount of pregelatinized partially hydrolyzed starch added to the slurry, prepared according to the embodiments of the present invention, should range from between the aforementioned endpoints listed in Table 3A or 3B, or any of them. Can be done.

The pregelatinized partially hydrolyzed starch prepared according to the embodiments of the present invention can be added to the slurry in combination with other starches in some embodiments of various uses. For example, in the case of the gypsum wallboard described below, the pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention may be combined with other starches, especially if some increase in water requirements is tolerated. In combination, core strength and paper-core coupling can be improved.

Thus, in some embodiments of the invention, the gypsum slurry comprises one or more pregelatinized partially hydrolyzed starches prepared according to the embodiments of the invention and one or more other types of starch. It may be. Other starches may include, for example, pregelatinized starches having viscosities less than 20 centipores and / or viscosities greater than 700 cmpores. One example is pregelatinized corn starch (eg, with a viscosity greater than 700 centipores, such as about 773 cmpores). Other starches may be in the form of non-pregelatinized starches such as acid-modified starches and alkylated starches such as ethylated starches which are not gelatinized. The starch combination may be premixed (eg, in dry mixing, optionally with other ingredients such as stucco, or in wet mixing with other moist ingredients) prior to addition to the gypsum slurry, or one of them. They may be incorporated into gypsum slurries one by one, or any modification thereof. The pregelatinized partially hydrolyzed starch prepared according to the embodiment of the present invention, and other starches may be contained in any suitable ratio.

For example, the starch content of pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention can be, for example, about 10% by weight or more, in percent of the total starch content added to the gypsum slurry, eg, about. 20% or more, about 30% or more, about 40% or more, about 50% or more, about 60% or more, about 70% or more, about 80% or more, about 90% or more, about 95% or more, about 99% or more, about It can be 100% or more, or any range in between. In some embodiments, the ratio of pregelatinized partially hydrolyzed starch to other starches prepared according to embodiments of the present invention is about 25:75, about 30:70, about 35:65, about 50:50. , About 65:35, about 70:30, about 75:25, etc.

In some embodiments, in addition to the starch component, the slurry is formulated to contain water, stucco, a foaming agent (sometimes simply referred to as "foam") and, if desired, other additives. Will be done. Surprisingly and unexpectedly, the same as without pregelatinized partially hydrolyzed starch prepared in an extruder according to the embodiments of the present invention according to some embodiments, especially according to embodiments showing moderate viscosity. It has been found that the amount of water that needs to be added to maintain a level of slurry fluidity is less than the increment of the amount of water needed when using starch prepared according to different methods. There is. Stucco can be in the form of alpha calcium sulphate hemihydrate, beta calcium sulphate hemihydrate and / or calcium sulphate anhydride. The stucco can be fibrous or non-fibrous. A foaming agent can be incorporated to form a void distribution within the continuous crystalline matrix of the hardened gypsum. In some embodiments, the foaming agent comprises an unstable component of the main weight portion and a stable component of the light weight portion (eg, a blend of unstable and stable / unstable). case). The weight ratio of the unstable component to the stable component is effective in forming the void distribution inside the hardened gypsum core. See, for example, U.S. Pat. Nos. 5,643,510, 6,342,284 and 6,632,550.

It has been found that suitable clearance distribution and wall thickness (independently) can be effective in improving strength, especially on lower density boards (eg, less than about 35 pcf). See, for example, U.S. Patent Application Publication Nos. 2007/0048490 and 2008/090068. The evaporated water gap generally has a gap having a diameter of about 5 μm or less, and contributes to the total gap distribution together with the above-mentioned voids (bubbles). In some embodiments, the volume ratio of pores with pore sizes greater than about 5 microns to pores with pore sizes greater than about 5 microns is from about 0.5: 1 to about 9: 1. Yes, for example, about 0.7: 1 to about 9: 1, about 0.8: 1 to about 9: 1, about 1.4: 1 to about 9: 1, about 1.8: 1 to about 9: 1. , About 2.3: 1 to about 9: 1, about 0.7: 1 to about 6: 1, about 1.4: 1 to about 6: 1, about 1.8: 1 to about 6: 1, about 0.7: 1 to about 4: 1, about 1.4: 1 to about 4: 1, about 1.8: 1 to about 4: 1, about 0.5: 1 to about 2.3: 1, about 0.7: 1 to about 2.3: 1, about 0.8: 1 to about 2.3: 1, about 1.4: 1 to about 2.3: 1, about 1.8: 1 to about 2 .3: 1 mag. In some embodiments, the effervescent agent is present in the slurry in an amount of, for example, less than about 0.5% by weight of stacco, eg, about 0.01% to about 0.5% by weight of stacco, about 0%. 0.01% by weight to about 0.4% by weight, about 0.01% by weight to about 0.3% by weight, about 0.01% by weight to about 0.2% by weight, about 0.01% by weight to about 0. Exists in an amount of 1% by weight, about 0.02% by weight to about 0.4% by weight, about 0.02% by weight to about 0.3% by weight, about 0.02% by weight to about 0.2% by weight, etc. do.

Additives such as accelerators (eg, wet gypsum accelerators, heat resistance accelerators, environmental stability accelerators) and retarders are well known and can be included in some embodiments. See, for example, US Pat. Nos. 3,573,947 and 6,409,825. In some embodiments that include an accelerator and / or a retarder, the accelerator and / or the retarder, respectively, on a solid basis, are, for example, from about 0% to about 10% by weight (eg, about 0.1%) of gypsum. % ~ About 10%) can be present in the gypsum slurry, eg in an amount of about 0% to about 5% by weight (eg about 0.1% to about 5%) of stucco in the gypsum slurry. Can exist. If desired, other additives may be incorporated to allow, for example, a low-weight product that is given strength to provide sufficient strength and may prevent permanent distortion, eg, the product on a conveyor going down the production line. In some cases, the raw strength may be increased, the fire resistance may be increased, the water resistance may be increased, and the like.

For example, the slurry can optionally contain one or more dispersants to improve fluidity in some embodiments. The dispersant is in the core slurry in dry form with other dry components and / or in liquid form with other liquid components, such as pregelatinized partially hydrolyzed starch and other components prepared according to embodiments of the present invention. May be included in. Examples of dispersants include naphthalene sulfonic acids such as polynaphthalene sulfonic acid and salts thereof (polynaphthalene sulfonate) and derivatives which are condensation products of naphthalene sulfonic acid and formaldehyde; and poly such as polycarboxylic acid ether. Carboxylate dispersants such as PCE211, PCE111, 1641, 1641F, or PCE 2641 type dispersants such as MELFLUX 2641F, MELFLUX 2651F, MELFLUX 1641F, MELFLUX 2500L dispersant (BASF), and Coatex, Inc. COATEX Ethacryl M; and / or lignosulfonate or sulfonated lignin, available from. Lignosulfonate is a water-soluble anionic polyelectrolyte polymer that is a by-product of wood pulp production using sulfite pulping. An example of a lignin useful in practicing the principles of the embodiments of the present invention is Marasperse C-21, available from Reed Lignin Inc.

Lower molecular weight dispersants are generally preferred. Lower molecular weight naphthalene sulfonic acid dispersants are preferred because they tend to require less water than higher viscous and high molecular weight dispersants. Therefore, a molecular weight of about 3,000 to about 10,000 (eg, about 8,000 to about 10,000) is preferred. As another example for the PCE211 type dispersant, in some embodiments, the molecular weight can be from about 20,000 to about 60,000, less than a dispersant having a molecular weight greater than 60,000. Indicates a delay.

An example of naphthalene sulfonate is DILOFLO available from GEO Specialty Chemicals. DILOFLO is a 45% aqueous naphthalene sulfonate solution, but other aqueous solutions with a solid content ranging from, for example, about 35% to about 55% by weight are also readily available. Naphthalene sulfonates can be used in dry solid or powder form, for example LOMARD, available from GEO Specialty Chemicals. Another preferred naphthalene sulfonate is Hampsire Chemical Corp. DAXAD available from.

When a dispersant is included, the dispersant can be included in any suitable (solid / solid) amount, eg, in an amount of about 0.1% to about 5% by weight based on the weight of the stucco. Can be, for example, about 0.1% to about 4%, about 0.1% to about 3%, about 0.2% to about 3%, about 0.5% to about 3%, about 0.5%. It can be contained in an amount of about 2.5%, about 0.5% to about 2%, about 0.5% to about 1.5%, and the like.

In some embodiments, one or more phosphoric acid-containing compounds can optionally be included in the slurry, if desired. For example, the phosphate-containing components useful in some embodiments include water-soluble components, where the phosphate-containing component is an ion, salt, or acid, ie condensed phosphorus, each containing two or more phosphoric acid units. Acids; salts or ions of condensed phosphates, each containing two or more phosphate units; and monobasic or monovalent ions of orthophosphate, and in the form of water-soluble acyclic polyphosphates. There can be. See, for example, U.S. Pat. Nos. 6,342,284, 6,632,550, 6,815,049, and 6,822,033.

When a phosphate composition is added in some embodiments, the phosphate composition can improve biostrength, resistance to permanent strain (eg, sagging), dimensional stability, and the like. For example, trimetaphosphate compounds including sodium trimetaphosphate, potassium trimetaphosphate, lithium trimetaphosphate, and ammonium trimetaphosphate can be used. Sodium trimetaphosphate (STMP) is preferred, for example sodium tetramethaphosphate, having a phosphate repeat unit of about 6 to about 27 and having a molecular formula _{Nan + 2} P _n O _{3n + 1} (in the formula, n = 6 to 27). Sodium hexametaphosphate with, tetrapotassium pyrophosphate with molecular formula K ₄ P ₂ O _{7 , dipotassium tripoly sodium tripolyphosphate with molecular formula Na 3} K ₂ P ₃ O ₁₀ , sodium tripolyphosphate with molecular formula Na ₅ P ₃ O ₁₀ , Tetrasodium pyrophosphate with molecular formula Na ₄ P ₂ O ₇ , aluminum trimetaphosphate with molecular formula Al (PO ₃ ) ₃ , acidic sodium pyrophosphate with _{molecular formula Na 2} H ₂ P ₂ O _{7, 1,000-3,000} Ammonium polyphosphate having multiple phosphate repeat units and having the molecular formula (NH ₄ ) _{n + 2} P _n O _{3n + 1} (in the formula, n = 1,000-3,000), or two or more phosphates. Other phosphates, including polyphosphoric acid, having repeating units and having the molecular formula H _{n + 2} P _n O _{3 n + 1} (where n is 2 or more) may be suitable.

In some embodiments, the phosphate can be contained in dry form or in water form (eg, about 5% to about 20% phosphate solution, such as about 10% solution, etc.). When a phosphate is included, the phosphate can be in any suitable amount (solid / solid basis), for example from about 0.01% to about 0.5% by weight based on the weight of the stacco. Can be, for example, from about 0.03% to about 0.4% by weight, from about 0.1% to about 0.3% by weight, or from about 0.12% to about 0.4% by weight, based on the weight of the stacco. Can be% by weight.

Additives suitable for fireproof evaluated products and / or water resistant products can also be optionally included, and suitable additives include, for example, siloxane (water resistance); fiber; aluminum trihydrate ( ATH), a heat-absorbing additive such as magnesium hydroxide or the like; and / or highly expansive particles (eg, which can expand to about 300% or more of their original volume when heated at 1560 ° F for about 1 hour). Can be mentioned. For a description of these and other ingredients, see, for example, US Application No. 13 / 400,010 by the same applicant (filed February 17, 2012), which is pending at the same time. In some embodiments, high expansion vermiculite is included, but other refractory materials can be included. The boards of some refractory-evaluated products of the present invention have an adiabatic index (TI) of about 17 minutes or longer, such as about 20 minutes or longer, about 30 minutes or longer, about 45 minutes or longer, about 60 minutes or longer; / Or can have high temperature shrinkage in the xy direction of less than about 10% (at a temperature of about 1560 ° F (850 ° C.)) and expansion in the z direction of more than about 20%. The fire-resistant or water-resistant additive may be contained in a suitable arbitrary amount, if desired, depending on, for example, a fire resistance evaluation. For example, when a fire or water resistant additive is included, the fire or water resistant additive can be in an amount of about 0.5% to about 10% by weight of the stacco, eg, about 1% to about 1% by weight of the stacco. It can be 10% by weight, about 1% by weight to about 8% by weight, about 2% by weight to about 10% by weight, about 2% by weight to about 8% by weight, and the like.

In some embodiments, if a siloxane is included, the siloxane is preferably added in the form of an emulsion. The slurry is then molded and dried under conditions that promote polymerization of the siloxane to form a highly crosslinked silicone resin. A catalyst that promotes the polymerization of siloxane to form a highly crosslinked silicone resin can be added to the gypsum slurry. In some embodiments, a solvent-free methyl hydrogen siloxane solution sold by Wacker-Chemie GmbH (Munich, Germany) under the name SILRES BS 94 can be used as the siloxane. This product is a siloxane solution that does not contain water or solvent. In some embodiments, it is intended that about 0.3% to about 1.0% BS 94 siloxane may be used based on the weight of the dry component. For example, in some embodiments, it is preferable to use about 0.4% to about 0.8% siloxane based on the weight of the dried stucco.

The slurry formulation can be made at any suitable water / stucco ratio, for example at a ratio of about 0.4 to about 1.3. However, the pregelatinized partially hydrolyzed starches prepared according to embodiments of the present invention reduce the amount of water that needs to be added to the slurry in which they are placed, so in some embodiments other starches (eg different). Compared to conventional pregelatinized starches prepared according to the method), this slurry uses a lower water / stucco ratio input than conventional gypsum slurries containing other starches, especially lower weight. / Can be blended in density. For example, in some embodiments, the water / stucco ratio is about 0.4 to about 1.1, about 0.4 to about 0.9, about 0.4 to about 0.85, about 0.45. ~ About 0.85, about 0.55 to about 0.85, about 0.55 to about 0.8, about 0.6 to about 0.9, about 0.6 to about 0.85, about 0.6 It can be ~ about 0.8 mag.

The cover sheet can be formed of any suitable material and basis weight. Advantageously, the board core formed from the pregelatinized partially hydrolyzed starch-containing slurry prepared according to embodiments of the present invention, in some embodiments, is, for example, less than 45 lbs / MSF (eg, about 33 lbs / MSF to 45 lbs /). It provides sufficient strength even on boards with lower basis weight cover sheets such as MSF), and sufficient strength even on lower weight boards (eg having a density of about 35 pcs or less). I will provide a. However, in some embodiments, heavier basis weights are used if desired, for example to further improve nail pull resistance or to improve the feel, for example the desired "feel" properties for the end user. Can be promoted.

In some embodiments, one or both cover sheets can be formed from paper and, for example, about 45 lbs /, to increase strength (eg, nail pulling strength), especially with lower density boards. MSF or higher (eg, about 45 lbs / MSF to about 65 lbs / MSF, about 45 lbs / MSF to about 60 lbs / MSF, about 45 lbs / MSF to about 55 lbs / MSF, about 50 lbs / MSF to about 65 lbs / MSF, about 50 lbs / MSF to about It can have a basis weight of 60 lbs / MSF, etc.). If desired, in some embodiments, one cover sheet (eg, the "front" side when installed) has the higher basis weight described above, eg nail pull resistance and The feel can be improved and other cover sheets (eg, the "back" sheet when the board is installed) can have a somewhat lower basis weight if desired (eg less than about 45 lbs / MSF). Basis weight, eg, about 33 lbs / MSF to 45 lbs / MSF, or about 33 lbs / MSF to about 40 lbs / MSF).

Board weight is a function of thickness. Since boards are generally made of various thicknesses, board density is used herein as a measure of board weight. Advantages of pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention can be seen over various board densities, such as board densities of about 40 pcf or less, such as about 20 pcf to about 40 pcf, about 24 pcf to. It is about 37 pcf and the like. However, preferred embodiments of the present invention have specific utility at low densities and are prepared according to different methods due to the increased strength provided by the pregelatinized partially hydrolyzed starch prepared according to the embodiments of the present invention. It allows the use of lower weight boards, which have better strength and lower water requirements than boards made from other starches.

For example, in some embodiments, the board density can be from about 20 pcf to about 35 pcf, eg, about 20 pcf to about 34 pcf, about 20 pcf to about 33 pcf, about 20 pcf to about 32 pcf, about 20 pcf to about 31 pcf, About 20 pcs to about 30 pcs, about 20 pcs to about 29 pcs, about 21 pcs to about 35 pcs, about 21 pcs to about 34 pcs, about 21 pcs to about 33 pcs, about 21 pcs to about 32 pcs, about 21 pcs to about 31 pcs. Approximately 29 pcs, about 24 pcs to about 35 pcs, about 24 pcs to about 34 pcs, about 24 pcs to about 33 pcs, about 24 pcs to about 32 pcs, about 24 pcs to about 31 pcs, or about 24 pcs to about 30 pcs. can.

Pregelatinized partially hydrolyzed starch prepared according to embodiments of the invention can be added to the slurry to increase the strength of the products of the invention, which can be particularly advantageous at lower weights / densities. .. For example, in some embodiments, boards made according to embodiments of the present invention have a density of 29 pcf and a compressive strength of about 400 psi (2,750 kPa) or higher when tested according to the methods described in Example 4. Has. Advantageously, in various embodiments at various board densities described herein, the boards produced by the methods of the invention are about 400 psi or more, such as about 450 psi (3,100 kPa) or more, about 500 psi ( 3,450 kPa) or higher, about 550 psi (3,800 kPa) or higher, about 600 psi (4,100 kPa) or higher, about 650 psi (4,500 kPa) or higher, about 700 psi (4,800 kPa) or higher, about 750 psi (5,200 kPa) or higher , About 800 psi (5,500 kPa) or more, about 850 psi (5,850 kPa) or more, about 900 psi (6,200 kPa) or more, about 950 psi (6,550 kPa) or more, or about 1,000 psi (6,900 kPa) or more It can be prepared to have strength. Moreover, in some embodiments, the compressive strength can be limited by any two of the strength points described above. For example, the compressive strength can be about 450 psi to about 1,000 psi (for example, about 500 psi to about 900 psi, about 600 psi to about 800 psi, etc.).

In some embodiments, the boards made according to the present invention conform to the test protocol of ASTM standard C473-10. For example, in some embodiments, when the board is molded to a thickness of 1/2 inch, the board has a nail pulling resistance of about 65 lbs or more as measured according to ASTM C473-10, eg about 68 lbs. As described above, it has nail pulling resistance of about 70 lb or more, about 72 lb or more, about 75 lb or more, about 77 lb or more, and the like. In various embodiments, the nail pulling resistance can be from about 68 lbs to about 100 lbs, eg, about 68 lbs to about 95 lbs, about 68 lbs to about 90 lbs, about 68 lbs to about 85 lbs, about 68 lbs to about 80 lbs, about 68 lbs. ~ About 77 lb, about 68 lb ~ about 75 lb, about 68 lb ~ about 72 lb, about 68 lb ~ about 70 lb, about 70 lb ~ about 100 lb, about 70 lb ~ about 95 lb, about 70 lb ~ about 90 lb, about 70 lb ~ about 85 lb, about 70 lb ~ about 80 lb, about 70 lb to about 77 lb, about 70 lb to about 75 lb, about 70 lb to about 72 lb, about 72 lb to about 100 lb, about 72 lb to about 95 lb, about 72 lb to about 90 lb, about 72 lb to about 85 lb, about 72 lb to about 80 lb, About 72 lbs to about 77 lbs, about 72 lbs to about 75 lbs, about 75 lbs to about 100 lbs, about 75 lbs to about 95 lbs, about 75 lbs to about 90 lbs, about 75 lbs to about 85 lbs, about 75 lbs to about 80 lbs, about 75 lbs to about 77 lbs, about 77 lbs. It can be from about 100 lbs, about 77 lbs to about 95 lbs, about 77 lbs to about 90 lbs, about 77 lbs to about 85 lbs, or about 77 lbs to about 80 lbs.

With respect to bending strength, in some embodiments, when molded on a board with a thickness of 1/2 inch, the board is about 36 lbs or more in the length direction (eg, about 38 lbs or more) as measured according to ASTM standard C473. , About 40 lb or more) and / or has a bending strength of about 107 lb or more (for example, about 110 lb or more, about 112 lb or more, etc.) in the width direction. In various embodiments, the board can have bending strength in the length direction of about 36 lbs to about 60 lbs, eg, about 36 lbs to about 55 lbs, about 36 lbs to about 50 lbs, about 36 lbs to about 45 lbs, about 36 lbs. ~ About 40 lb, about 36 lb ~ about 38 lb, about 38 lb ~ about 60 lb, about 38 lb ~ about 55 lb, about 38 lb ~ about 50 lb, about 38 lb ~ about 45 lb, about 38 lb ~ about 40 lb, about 40 lb ~ about 60 lb, about 40 lb ~ about It can have bending strength in the length direction of 55 lbs, about 40 lbs to about 50 lbs, or about 40 lbs to about 45 lbs. In various embodiments, the board can have bending strength in the width direction of about 107 lbs to about 130 lbs, eg, about 107 lbs to about 125 lbs, about 107 lbs to about 120 lbs, about 107 lbs to about 115 lbs, about 107 lbs. About 112 lbs, about 107 lbs to about 110 lbs, about 110 lbs to about 130 lbs, about 110 lbs to about 125 lbs, about 110 lbs to about 120 lbs, about 110 lbs to about 115 lbs, about 110 lbs to about 112 lbs, about 112 lbs to about 130 lbs, about 112 lbs to about 125 lbs. , About 112 lbs to about 120 lbs, or about 112 lbs to about 115 lbs in the width direction.

Further, in some embodiments, the board can have an average core hardness of about 11 lbs or more when measured according to ASTM C473-10, eg, about 12 lbs or more, about 13 lbs or more, about 14 lbs or more, about 15 lbs. As mentioned above, it can have an average core hardness of about 16 lb or more, about 17 lb or more, about 18 lb or more, about 19 lb or more, about 20 lb or more, about 21 lb or more, or about 22 lb or more. In some embodiments, the board can have a core hardness of about 11 lbs to about 25 lbs, eg, about 11 lbs to about 22 lbs, about 11 lbs to about 21 lbs, about 11 lbs to about 20 lbs, about 11 lbs to about 19 lbs, About 11 lb to about 18 lb, about 11 lb to about 17 lb, about 11 lb to about 16 lb, about 11 lb to about 15 lb, about 11 lb to about 14 lb, about 11 lb to about 13 lb, about 11 lb to about 12 lb, about 12 lb to about 25 lb, about 12 lb ~ About 22 lb, about 12 lb ~ about 21 lb, about 12 lb ~ about 20 lb, about 12 lb ~ about 19 lb, about 12 lb ~ about 18 lb, about 12 lb ~ about 17 lb, about 12 lb ~ about 16 lb, about 12 lb ~ about 15 lb, about 12 lb ~ about 14 lb, about 12 lb to about 13 lb, about 13 lb to about 25 lb, about 13 lb to about 22 lb, about 13 lb to about 21 lb, about 13 lb to about 20 lb, about 13 lb to about 19 lb, about 13 lb to about 18 lb, about 13 lb to about 17 lb, About 13 lbs to about 16 lbs, about 13 lbs to about 15 lbs, about 13 lbs to about 14 lbs, about 14 lbs to about 25 lbs, about 14 lbs to about 22 lbs, about 14 lbs to about 21 lbs, about 14 lbs to about 20 lbs, about 14 lbs to about 19 lbs, about 14 lbs. ~ About 18 lb, about 14 lb ~ about 17 lb, about 14 lb ~ about 16 lb, about 14 lb ~ about 15 lb, about 15 lb ~ about 25 lb, about 15 lb ~ about 22 lb, about 15 lb ~ about 21 lb, about 15 lb ~ about 20 lb, about 15 lb ~ about 19 lb, about 15 lb to about 18 lb, about 15 lb to about 17 lb, about 15 lb to about 16 lb, about 16 lb to about 25 lb, about 16 lb to about 22 lb, about 16 lb to about 21 lb, about 16 lb to about 20 lb, about 16 lb to about 19 lb, About 16 lbs to about 18 lbs, about 16 lbs to about 17 lbs, about 17 lbs to about 25 lbs, about 17 lbs to about 22 lbs, about 17 lbs to about 21 lbs, about 17 lbs to about 20 lbs, about 17 lbs to about 19 lbs, about 17 lbs to about 18 lbs, about 18 lbs. ~ About 25 lb, about 18 lb ~ about 22 lb, about 18 lb ~ about 21 lb, about 18 lb ~ about 20 lb, about 18 lb ~ about 19 lb, about 19 lb ~ about 25 lb, about 19 lb ~ about 22 lb, about 19 lb ~ about 21 lb, about 19 lb ~ about It can have a core hardness of 20 lbs, about 21 lbs to about 25 lbs, about 21 lbs to about 22 lbs, or about 22 lbs to about 25 lbs.

Due, at least in part, to the moderate viscosity properties obtained in some embodiments of the invention, these criteria (eg, nail pull resistance, bending strength and core strength) are very low as described herein. Density boards (eg, about 31 pcf or less) can also be adapted.

Pregelatinized partially hydrolyzed starch prepared according to an embodiment of the present invention is temperature-raised-cured to match or exceed the temperature-increasing curing (TRS) hydration rate of conventional pregelatinized starch prepared according to different methods. It has been found by the inventors to indicate the (TRS) hydration rate. The desired cure time may vary depending on the formulation and the desired cure time may be determined by one of ordinary skill in the art depending on the plant conditions and available raw materials.

The product of the embodiment of the present invention can be produced on a typical production line. For example, board manufacturing techniques are described, for example, in US Pat. No. 7,364,676 and US Patent Application Publication No. 2010/0247937. Briefly, in the case of gypsum board, the process usually involves discharging the cover sheet onto a moving conveyor. In such an embodiment, this cover sheet is a "front" cover sheet, since gypsum board is usually formed "front down".

The dry and / or wet components of the gypsum slurry are fed to a mixer (eg, a pin mixer) and stirred to form the gypsum slurry. The mixer comprises a body and a drain conduit (eg, a gate-canister-boot arrangement known to those of skill in the art, or the arrangement described in US Pat. Nos. 6,494,609 and 6,874,930). .. In some embodiments, the drain conduit can include a slurry distributor with either one supply port or multiple supply ports, eg, US Patent Application Publication No. 2012/0168527 (A1) (A1). Slurry distributors and the like described in Application No. 13 / 341,016) and 2012/010403 (A1) (Application No. 13 / 341,209) can be included. In those embodiments using slurry distributors with multiple supply ports, the drain conduit can include a suitable flow splitter, eg, U.S. Patent Application Publication No. 2012/0170403 (A1). Flow splitter and the like can be included. The foaming agent can be added to the outlet conduit of the mixer (eg, to the gates described in US Pat. Nos. 5,683,635 and 6,494,609) or to the body, if desired. The foaming agent-containing slurry, which is discharged from the discharge conduit after all the ingredients have been added, is the main gypsum slurry and forms the gypsum core. This board core slurry is discharged onto the moving front cover sheet.

The front cover sheet may have a thin skim coat in the form of a relatively dense slurry layer. Further, as known to those skilled in the art, a hard edge can be formed from the same slurry flow that forms the front skim coat. In embodiments where the foam is placed in the discharge conduit, the second gypsum slurry stream can be removed from the mixer body to form a dense skim coat slurry, which can then be used as known to those of skill in the art. A front skim coat and a hard edge can be formed. If front skim coats and hard edges are included, the front skim coats and hard edges are usually placed upstream of the mixer, on the moving front cover sheet, before placing the core slurry. After being discharged from the discharge conduit, the core slurry is spread on a front cover sheet (optionally with a skim coat) and covered with a second cover sheet (usually a "back" cover sheet) in the form of a sandwich structure. To form a wet assembly. This is the final product board precursor. The second cover sheet may optionally have a second skim coat, which is formed from a second (dense) gypsum slurry that is the same as or different from the front skim coat if a front skim coat is present. Can be made to. The cover sheet may be made of paper, fiber mats, or other types of materials such as foils, plastics, glass mats, non-woven materials such as blends of cellulose fillers and inorganic fillers.

The wet assembly provided thereby is transported to a molding site, where the product is sized to the desired thickness (eg, by a molding plate), and then transported to one or more knife cutting areas, where the product is desired. Cut to length. The wet assembly is cured to form a linked crystal matrix of hardened gypsum and a drying process is used to remove excess water (eg, by moving the assembly through a furnace). Surprisingly and unexpectedly, boards prepared according to the present invention using pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention are required in the drying process due to the low starch water requirement characteristics. It has been found that the time required for this is significantly less. This is advantageous because it reduces energy costs.

It is also common to use vibration in the manufacture of gypsum board to remove large gaps or air pools from the placed slurry. Each of the above steps, as well as processes and devices that perform such steps, are known to those of skill in the art.

Pregelatinized partially hydrolyzed starches prepared according to embodiments of the present invention include, for example, gypsum wallboards, acoustic (eg, ceiling) tiles, joint compounds, gypsum-cellulose fiber products such as gypsum-xylem fiber wallboards, and the like. It can be used in blending various products such as gypsum. In some embodiments, such products can be formed from the slurries of the embodiments of the present invention.

Thus, pregelatinized partially hydrolyzed starch prepared in an extruder according to an embodiment of the present invention is also advantageous in products other than the paper surface gypsum board of the embodiment of the present invention, as described herein. Can have an effect. For example, pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention can be used in mat surface products (eg woven fabrics) in which the board cover sheet is in the form of a fiber mat. The mat can optionally have a topcoat to reduce water permeability. Other components that may be included in the manufacture of such matte surface products, as well as materials and methods for making fiber mats, are discussed, for example, in US Pat. No. 8,070,895 and US Patent Application Publication No. 2009/0247937. ing.

In addition, gypsum-cellulose products include cellulose host particles (eg, xylem fibers), gypsum, pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention, and other components if desired (eg, siloxane, etc.). It can be in the form of a water resistant additive). Other ingredients and manufacturing methods include, for example, U.S. Pat. Nos. 4,328,178, 4,239,716, 4,392,896, 4,645,548, and 5, It is discussed in 320,677, 5,817,262, and 7,413,603.

Examples of Embodiment In one embodiment, the method for producing pregelatinized partially hydrolyzed starch is as follows: (a) at least water, non-pregelatinized starch, and a weak acid that does not substantially chelate calcium ions are mixed. To make a wet starch precursor having a moisture content of about 8% to about 25% by weight; (b) feed the wet starch precursor to the extruder; and (c) this wet starch precursor. Includes pregelatinization and acid modification with the above extruders at die temperatures from about 150 ° C. (about 300 ° F.) to about 210 ° C. (about 410 ° F.).

In another embodiment, the pressure inside the extruder is about 2,000 psi or higher.

In another embodiment, the pregelatinized partially hydrolyzed starch has a cold water solubility greater than about 50%.

In another embodiment, the pregelatinized partially hydrolyzed starch has a cold water viscosity (10% solid, 25 ° C.) of about 10 lavender units (BU) to about 120 BU.

In another embodiment, the pregelatinized partially hydrolyzed starch has a viscosity characteristic of about 20 centipoise to about 700 cmpoise when the viscosity is measured while subjecting the starch to the conditions of the VMA method.

In another embodiment, the pregelatinized partially hydrolyzed starch has a viscosity of about 5 BU to about 33 BU (10% solid, 93 ° C.).

In another embodiment, the weak acid that does not substantially chelate calcium ions comprises alum.

In another embodiment, tartaric acid is included during mixing to form a wet starch precursor.

In another embodiment, the weak acid that does not substantially chelate calcium ions is in an amount of about 0.5% to about 5% by weight by weight of starch.

In another embodiment, the wet starch has a moisture content of about 10% to about 20% by weight by weight of the starch precursor.

In another embodiment, pregelatinization and acid denaturation occur in the extruder at die temperatures from about 175 ° C. (about 350 ° F.) to about 205 ° C. (about 400 ° F.).

In another embodiment, the production of pregelatinized partially hydrolyzed starch in the extruder is about 100 kg / hour or more.

In another embodiment, pregelatinization and acid denaturation occur in less than about 5 minutes.

In another embodiment, pregelatinization and acid denaturation occur in less than about 1 minute.

In another embodiment, the method does not have a step of purifying pregelatinized partially hydrolyzed starch.

In another embodiment, the method does not have a step of neutralizing pregelatinized partially hydrolyzed starch.

In another embodiment, the pregelatinized partially hydrolyzed starch is gelatinized by about 70% or more.

In another embodiment, the pregelatinized partially hydrolyzed starch is prepared according to an embodiment of the present invention.

In another embodiment, the method for making pregelatinized partially hydrolyzed starch is: (a) a mixture of at least water, non-pregelatinized starch and a strong acid, with a water content of about 8% by weight to about 25% by weight. The above-mentioned strong acid is to be produced in an amount of about 0.05% by weight or less of the weight of the above-mentioned starch; (b) the above-mentioned wet starch is hydrolyzed. And (c) pregelatinizing the above-mentioned wet starch with the above-mentioned extruder at a die temperature of about 150 ° C. (about 300 ° F) to about 210 ° C. (about 410 ° F) and acid. Including degeneration.

In another embodiment, the method for making pregelatinized partially hydrolyzed starch is: (a) a mixture of at least water, non-pregelatinized starch and a strong acid, with a water content of about 8% by weight to about 25% by weight. The above-mentioned strong acid is to be produced in an amount of about 0.01% by weight or less of the weight of the above-mentioned starch; (b) the above-mentioned wet starch is hydrolyzed. And (c) pregelatinizing the above-mentioned wet starch with the above-mentioned extruder at a die temperature of about 150 ° C. (about 300 ° F) to about 210 ° C. (about 410 ° F) and acid. Including degeneration.

In another embodiment, the strong acid has a pKa of about -1.7 or less.

In another embodiment, the strong acid is sulfuric acid, nitric acid, hydrochloric acid, or any combination thereof.

In another embodiment, the method of making the board has (a) (i) at least water, non-pregelatinized starch and acid mixed to have a water content of about 8% by weight to about 25% by weight. By forming a wet starch precursor, the above acids are (1) weak acids that do not substantially chelate calcium ions, and (2) in an amount of about 0.05% by weight or less of the weight of the above starch. Forming selected from the group consisting of certain strong acids, or (3) any combination thereof; (ii) feeding the wet starch precursors described above to the extruder; and (iii) the wet starches described above. Forming pregelatinized partially hydrolyzed starch by pregelatinization and acid modification with the above-mentioned extruder having a die having a temperature of about 150 ° C. (about 300 ° F.) to about 210 ° C. (about 410 ° F.). (B) Mix this pregelatinized partially hydrolyzed starch with at least water and stacco to form a slurry; (c) Place this slurry between the first and second cover sheets. It involves forming a wet assembly; (d) cutting the wet assembly into a board; and (e) drying the board.

In another embodiment, the strong acid is in an amount no more than about 0.01% by weight by weight of starch.

In another embodiment, the method of making the board is to mix (a) (i) at least water, non-pregelatinized starch, and an acid that does not substantially chelate calcium ions, from about 8% by weight. To make a wet starch precursor having a water content of about 25% by weight; (ii) feed the wet starch precursor to the extruder; and (iii) to feed the wet starch above to about 150 ° C. (about). Forming pregelatinized partially hydrolyzed starch by pregelatinization and acid modification with the above-mentioned extruder having a die having a temperature of 300 ° F) to about 210 ° C (about 410 ° F); (b) this The pregelatinized partially hydrolyzed starch is mixed with at least water and stacco to form a slurry; (c) the slurry is placed between the first cover sheet and the second cover sheet to form a wet assembly. Allowing; (d) cutting the wet assembly into boards; and (e) including drying the boards.

In another embodiment, the method of making the board has (a) (i) at least water, non-pregelatinized starch and a strong acid mixed to have a water content of about 8% by weight to about 25% by weight. To make a wet starch precursor, wherein the strong acid is in an amount of about 0.05% by weight or less of the weight of the starch; (ii) the wet starch precursor is hydrolyzed. And (iii) pregelatinizing the above-mentioned wet starch with the above-mentioned extruder having a die having a temperature of about 150 ° C. (about 300 ° F) to about 210 ° C. (about 410 ° F) and Acid modification; (b) mixing pregelatinized partially hydrolyzed starch with at least water and stacco to form a slurry; (c) placing this slurry between the first and second cover sheets. To form a wet assembly; (d) cut the wet assembly into a board; and (e) dry the board.

In another embodiment, the strong acid is in an amount no more than about 0.01% by weight by weight of starch.

In another embodiment, the hardened gypsum core has greater compressive strength than the hardened gypsum core made with starch prepared differently.

In another embodiment, the pregelatinized partially hydrolyzed starch is gelatinized by about 70% or more when added to the slurry, which further gelatinizes during the drying step.

In another embodiment, the pregelatinized partially hydrolyzed starch is completely gelatinized when added to the slurry.

In another embodiment, the board has a density of 29 pcf and a compressive strength of about 400 psi (2,800 kPa) or higher.

In another embodiment, the board has a core hardness of about 11 or higher as measured according to ASTM C473-10.

In another embodiment, the board has a density of about 21 pcf to about 35 pcf.

In another embodiment, the slurry further comprises sodium trimetaphosphate.

In another embodiment, the amount of water that needs to be added to maintain the same level of slurry fluidity as in the absence of pregelatinized partially hydrolyzed starch is pregelatinized partially hydrolyzed starch prepared according to different methods. Less than the increment of the amount of water required when used.

In another embodiment, the starch is in an amount of about 0.5% to about 10% by weight based on the weight of the stucco.

In another embodiment, the wallboard is prepared according to an embodiment of the invention.

It should be noted that the above is merely an example of an embodiment. Other preferred embodiments are apparent from the entire description herein. It will also be appreciated by those skilled in the art that each of these embodiments may be used in various combinations with the other embodiments provided herein.

The following examples further illustrate the invention, but of course should not be construed as limiting its scope in any way.

Example 1
This example illustrates the preparation of pregelatinized partially hydrolyzed starch according to embodiments of the present invention.

Nine pregelatinized partially hydrolyzed starches prepared according to embodiments of the present invention were prepared for various tests of specific properties (eg viscosity, fluidity, strength). These nine starches of the invention were tested with three commercially available starches.

According to the method of the present invention for preparing pregelatinized partially hydrolyzed starch, wet starch precursors are composed of 100 kg of germ-removing cornmeal commercially available from Bunge North America (St. Louis, Missouri) as CCM 260 yellow cornmeal. Prepared by mixing different amounts of aluminum sulfate (alm), weak acids that substantially do not chelate calcium ions and / or tartrate (less than 20% by weight of total weak acids), and different amounts of water. Wet starch precursors were fed from American Extension International (South Beloit, Illinois) to a single-screw extruder marketed as Advantage 50. In the extruder, the wet starch precursor was pregelatinized and acid-denatured in one step so that pregelatinization and acid denaturation occurred simultaneously.

Table 4 below lists the extrusion parameters for cornflower in the presence of acid. The residence time of the extrusion (ie, the time for pregelatinization and acid denaturation) was less than 30 seconds. All percentages are based on the total weight of starch, while water is based on the total wet weight, expressed as the sum of water, starch and other additives.

The resulting pregelatinized partially hydrolyzed starches are conventional pregelatinized corn starch with a viscosity of 773 centipores (referred to as Composition 1A (comparative)), as well as Clinton 277 (ADM, Chicago, Illinois) and Caliber 159 (Cargill). As a control, two low-water requirement starches (referred to as Composition 1B (comparative) and Composition 1C (comparative), respectively) prepared by extrusion of acid-modified corn starch commercially available as Weissata, Minnesota. evaluated.

Pregelatinized partially hydrolyzed starch, referred to as compositions 1D-1L, was made by an extrusion process.

Table 5 below details the various moisture content of the compositions 1D-1L in extrusion and the acid content in extrusion. The compositions 1D to 1H and 1L were prepared with a water content of 16% by weight, and the compositions 1I and 1K were prepared with a water content of 13% by weight. Compositions 1D to 1G and compositions 1I to 1L were prepared using 1% to 4% by weight of alum solution, and composition 1H contained alum solution and tartaric acid. The compositions 1F and 1L were prepared using the same water content and the same amount of acid, but in Example 3 they have different amounts of retarder.

The following Examples 2-4 test the compositions listed in Table 5 for various properties. In Example 2, the compositions 1B to 1L were evaluated for viscosity in an amylograph test. Example 3 tested the fluidity of the slurry prepared using one of the compositions 1A, 1D-1I and 1K-1L and evaluated by slump test. This data was further confirmed by measuring the 50% hydration time of the slurry. This reveals how long it takes for the slurry to cure. Example 4 was tested for the strength of the slurry prepared with the compositions 1A, 1D-1I and 1K and evaluated by the compressive strength test described herein.

Example 2
This example illustrates the viscosity of pregelatinized partially hydrolyzed starch prepared in an extruder according to an embodiment of the present invention. Compositions 1D-1K were compared to extruded commercially available acid-modified starches (compositions 1B-1C) and tested for how the viscosity changes, especially based on the amount and water content of the acid (eg alum). .. Moisture content is defined by the moisture level of the wet starch supplied through the extruder.

In the test preparation, the composition was mixed with water to make a starch slurry such that the starch slurry contained the composition in an amount of 10% by weight. The term "solution" is used when the starch is completely gelatinized and completely dissolved, and the term "slurry" is used when the starch is not completely dissolved. Each composition was then tested for viscosities at different temperatures by the amylograph technique described herein. The test results are plotted in FIGS. 1 and 2. 1 and 2 assess the viscosity of pregelatinized partially hydrolyzed starch at different temperatures by plotting viscosity (left y-axis) and temperature (right y-axis) against time (x-axis). It is an amyogram to be used. The temperature curve is overlaid on each sample. The same temperature profile was used for each sample. The other curves show the viscosity of starch.

The initial viscosity at 25 ° C. was an index of the fluidity of the slurry system containing any one of the compositions 1B to 1K. 25 ° C. is the temperature at which starch is mixed with stucco and other ingredients to make a board. Moreover, at this temperature, the viscosity of starch has a negative correlation with the fluidity of the stucco slurry.

The viscosity at trough (93 ° C.) is an index of the molecular weight of any one of the compositions 1B to 1K. At a temperature of 93 ° C., the starch molecules are completely soluble in water. The viscosity of the starch solution at 93 ° C. has a positive correlation with the molecular weight of the starch obtained by partial hydrolysis.

FIG. 1 is an amyogram plotting viscosity (left y-axis) and temperature (right y-axis) over 50 minutes (x-axis). The comparative compositions 1B and 1C, as well as the compositions 1D and 1H of the invention described herein, were mixed to give a starch solution in an amount of 10% by weight based on the weight of the solution. To prevent the formation of lumps, the starch was added to the water in the mixing cup of the Waring blender with slow mixing for 20 seconds. The starch solution was then evaluated using Viscograph-E (CW Brabender® Instruments, Inc., South Hackensack, NJ). According to the procedure for measuring lavender viscosity described herein, for example, C.I. W. Viscosity is measured using a Brabender Viscograf. It should be noted that lavender units are measured at 75 RPM using a 16 fluid ounce (about 500 cc) size sample cup with a 700 cmg cartridge, as specified herein. As described herein, lavender units can be converted to other viscosity measurements such as centipores (eg, cP = BU x 2.1 if the measurement cartridge is 700 cmg) or Krebs units. Those skilled in the art will also easily recognize what they can do. The paste profile of the compositions 1D-1H extruded with a moisture content of 16% by weight is shown in FIG. 1 together with the comparative compositions 1B and 1C.

Considering the compositions 1D-1H of the present invention, as the alum increased from 1% by weight to 4% by weight, the initial viscosity decreased from 70 lavender units (BU) to 10 BU, and the molecular weight also decreased. The initial viscosities of the compositions 1D-1H and the viscosities at 93 ° C. were reduced to the same extent as the initial viscosities of the compositions 1B and 1C and the viscosities at 93 ° C. Compositions 1B and 1C represent conventional viscosity limits for low water requirements starch.

The results of compositions 1D-1H shown in FIG. 1 demonstrate that optimal acid denaturation can be obtained during extrusion. These results further suggest that the method of the present invention for preparing pregelatinized partially hydrolyzed starch successfully reduced the viscosity (molecular weight) of the starch. No viscosity peak was observed at 70 ° C. to 90 ° C., indicating that the compositions 1D-1H were completely gelatinized. Had the compositions 1D-1H not been completely gelatinized, there would have been an increase in viscosity. Complete gelatinization of the starch composition was confirmed by differential scanning calorimetry (DSC).

FIG. 2 is a second amylogram plotting viscosity (left y-axis) and temperature (right y-axis) over 50 minutes (x-axis). The comparative compositions 1B and 1C and the compositions 1I-1K of the invention described herein were mixed to give a starch solution in an amount of 10% by weight based on the weight of the solution. To prevent the formation of lumps, the starch was added to the water in the mixing cup of the Waring blender with slow mixing for 20 seconds. The starch solution was then evaluated using Viscograph-E. The paste profile of the compositions 1I-1K extruded with a moisture content of 13% by weight is shown in FIG. 2 together with the comparative compositions 1B and 1C.

A tendency similar to that observed with compositions 1D-1H was observed with compositions 1I-1K. In particular, the method of preparing pregelatinized partially hydrolyzed starch in an extruder, as described herein, successfully reduced the viscosities of compositions 1I-1K.

As the alum increased from 1% to 3% by weight, the initial viscosity decreased from 75BU to 14BU and the molecular weight also decreased. The initial viscosities of the compositions 1I-1K and the viscosity at 93 ° C. were reduced to the same extent as the initial viscosities of the compositions 1B and 1C and the viscosity at 93 ° C.

Furthermore, the results of compositions 1I-1K shown in FIG. 2 demonstrate that optimal acid denaturation can be obtained during extrusion. No viscosity peak was observed at 70 ° C. to 90 ° C., indicating that the compositions 1I-1K were completely gelatinized.

Furthermore, these results indicate that at a given acid level, more starch hydrolysis can be made at lower water content than at higher water content. This is because lower water content results in higher mechanical energy and therefore more starch degradation that results in smaller starches at the same acid level.

Example 3
This example illustrates the fluidity of a gypsum slurry containing compositions 1A (for comparison), 1D-1I, and 1K-1L. The composition was evaluated for fluidity using the slump test. The slump test will be understood by those skilled in the art.

In the preparation for the test, the slurry used was 2% by weight of the composition 1A (for comparison), 1D-1I, and 1K-1L, respectively, using the parameters listed in Table 6 below, and water. Prepared at a stucco ratio (WSR) of 100.

Starch was weighed into a dry mixture containing stucco with a purity greater than 95% and a heat resistance accelerator. Water, sodium trimetaphosphate (10 wt% solution), dispersant, and retarder were weighed into a mixing bowl of a Hobart mixer. The dry mixture was placed in a mixing bowl of a mixer available from Hobart (Troy, Ohio) as an N50 5-Quart mixer, soaked for 10 seconds and mixed at Speed II for 30 seconds. For foam preparation, a 0.5% solution of Hyonic® PFM-33 soap (available from GEO® Specialty Chemicals, Ambler, PA) was made and then mixed with air to create bubbles. .. Bubbles were added to the slurry using a foam generator.

Each slurry was then placed in a cylinder with a diameter of 4.92 cm (1.95 inches) and a height of 10 cm (3.94 inches). The cylinder was then pulled up to allow the slurry to flow freely. Next, the diameter formed by the slump was measured to illustrate the fluidity of the slurry. They are listed in Table 7 below. Table 8 also includes the results of the 50% hydration time test, which will be described in more detail below.

As can be observed from Table 7, the slurries prepared with the compositions 1D-1I and 1K showed a larger slump size than the slurries prepared with the composition 1A (for comparison). Slurries prepared with compositions 1D-1I and 1K cure faster than composition 1A (for comparison), and slurries containing compositions 1D-1I and 1K are better than slurries containing composition 1A. It was shown to have good fluidity.

In addition, the 50% hydration time of the slurry was measured to compare the slump size when the slurry cures at the same rate. The temperature profile of the slurry was measured using software as understood by those skilled in the art.

This further test was performed to confirm that the slump test was correct, especially the large slump observed in slurries containing pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention resulting from slow hydration. Instead, it was illustrated that it was the result of improved fluidity compared to composition 1A (for comparison).

The composition 1H prepared with 2% by weight alum and 0.3% by weight tartaric acid effectively hydrolyzed starch until it became low viscosity and had little effect on the hydration rate. This is because tartaric acid and alum have opposite effects on the rate of hydration.

FIG. 3 is a graph plotting temperature over time, showing the rate of elevated curing (TRS) hydration. Compositions 1F with 0.05% and 0.0625% retarders hydrate faster than or at the same rate as Composition 1A (comparative), respectively.

As seen in FIG. 3, composition 1L with 0.0625% by weight retarder had the same hydration rate as composition 1A (for comparison). The slump size of composition 1 L with 0.065 wt% retarder was 18.415 cm (7 1/4 inch), which was significantly larger than composition 1A.

This result indicates that the large slump size observed in the slurry containing pregelatinized partially hydrolyzed starch prepared according to the embodiment of the present invention was not due to slow curing but due to high fluidity. Suggest. In addition, pregelatinized partially hydrolyzed starch prepared according to embodiments of the present invention will allow wallboarding with less water without sacrificing fluidity.

Example 4
This example illustrates the strength of a gypsum disk prepared with a slurry containing compositions 1A (for comparison), 1D-1I, and 1K. Strength was assessed using the compressive strength test described herein.

To prepare for testing, the slurry was prepared using 2 wt% compositions 1A (for comparison), 1D-1I, and 1K-1L, respectively, using the parameters listed in Table 4 above. bottom.

A water stucco ratio (WSR) of 100 and air bubbles were used to make a gypsum disc with a final density of 29 pcf. Starch was weighed into a dry mixture containing stucco and a heat resistance accelerator. Water, a 10% sodium trimetaphosphate solution, a dispersant, and a retarder were weighed into a mixing bowl of a Hobart mixer. The dry mixture was placed in a mixing bowl of a mixer available from Hobart (Troy, Ohio) as an N50 5-Quart mixer, soaked for 10 seconds and mixed at Speed II for 30 seconds. For foam preparation, a 0.5% solution of Hyonic® PFM-33 soap (available from GEO® Specialty Chemicals, Ambler, PA) was made and then mixed with air to create bubbles. .. Bubbles were added to the slurry using a foam generator. The foam generator was operated at a speed sufficient to obtain the desired board density of 29 pcf. After adding the foam, the slurry was immediately poured to a point just above the top of the mold. As soon as the plaster hardened, the excess was scraped off. The mold was sprayed with a mold release agent (WD-40 ™). The disc was 10.16 cm (4 inches) in diameter and 1.27 cm (0.5 inches) thick.

After the disc had hardened, the disc was removed from the mold and then dried at 110 ° F. (43 ° C.) for 48 hours. After removal from the oven, the disc was allowed to cool at room temperature for 1 hour. Compressive strength was measured using a material test system commercially available from MTS Systems Corporation (Eden Prairie, Minnesota) as SATEC ^{TM E / M Systems.} The load was applied continuously at a speed of 0.04 inch / min (using a constant speed of 15-40 psi / sec) without impact. The results are shown in Table 8 below.

As can be seen in Table 8, the foam discs containing the compositions 1D-1I and 1K have compressive strength comparable to the foam discs containing the composition 1A (for comparison), and the pregelatinized partially hydrolyzed starch It was shown that the properties could be improved and the water requirement could be reduced without sacrificing strength. The desired compressive strength of the disk sample is about 400 psi. Strength is required so that the board can be handled properly without collapsing.

In the context of describing the present invention (especially in the context of the following claims) (eg, with respect to acid, raw material starch, or other ingredients or items), "one (a)" and "one (an)". ) ”And“ the ”and“ one or more (at least one) ”and the use of similar referents are not clearly inconsistent in context, unless otherwise specified herein. To the extent possible, it should be interpreted as covering both the singular and the plural. The use of the term "at least one" followed by an enumeration of one or more items (eg, "one or more of A and B") is otherwise provided herein. Means one item (A or B) selected from the listed items, or any combination of two or more of the listed items (A and B), unless there is a clear contradiction in the context. It needs to be interpreted as. The terms "comprising," "having," "inclusion," and "contining" are non-limiting terms (ie, "including," unless otherwise noted. , Not limited to that). The description of a range of values herein is merely intended to be treated as an abbreviation for individually referencing each separate value within that range, unless otherwise specified herein. Each separate value is incorporated herein as individually described herein. All of the methods described herein can be performed in any suitable order, unless otherwise specified herein or in clear context. The use of any example and all examples provided herein, or exemplary language (eg, "such as"), is merely intended to better illustrate the invention. , Unless otherwise requested, does not impose any restrictions on the scope of the present invention. The terms herein should not be construed as indicating any non-claiming element as essential to the practice of the present invention.

Preferred embodiments of the present invention are described herein and include the best embodiments of the present invention known to the inventors. Modifications of those preferred embodiments may be apparent to those skilled in the art by reading the aforementioned description. The inventors anticipate that those skilled in the art will use such variants as needed, and the inventors will implement the invention in ways other than those specifically described herein. Intended to be. Accordingly, the present invention includes, as permitted by applicable law, all modifications and all equivalents of subject matter described within the scope of the claims attached herein. Moreover, any combination of the above elements in all possible variations thereof is included by this disclosure unless otherwise specified herein or as clearly contradictory in context.

[Additional Notes]
[Appendix 1]
A method for producing pregelatinized partially hydrolyzed starch, wherein (a) at least water, non-pregelatinized starch, and a weak acid that does not substantially chelate calcium ions are mixed to obtain about 8% by weight. To make a wet starch precursor with a moisture content of about 25% by weight;
(B) Feeding the wet starch precursor to an extruder; and (c) the wet starch at a die temperature of about 150 ° C. (about 300 ° F) to about 210 ° C. (about 410 ° F). A method that includes pregelatinization and acid denaturation in an extruder.

[Appendix 2]
The method according to Appendix 1, wherein the weak acid that does not substantially chelate the calcium ion contains alum.

[Appendix 3]
The method according to Appendix 1 or 2, wherein tartaric acid is included in the mixture for producing the wet starch precursor.

[Appendix 4]
The method according to any one of Supplementary notes 1 to 3, wherein the method does not include a step of purifying the pregelatinized partially hydrolyzed starch and a step of neutralizing the starch.

[Appendix 5]
A method for producing pregelatinized partially hydrolyzed starch, wherein (a) at least water, non-pregelatinized starch and a strong acid are mixed and have a water content of about 8% by weight to about 25% by weight. To make a wet starch precursor, wherein the strong acid is in an amount of about 0.05% by weight or less of the weight of the starch;
(B) Feeding the wet starch precursor to an extruder; and (c) the wet starch at a die temperature of about 150 ° C. (about 300 ° F) to about 210 ° C. (about 410 ° F). A method that includes pregelatinization and acid denaturation in an extruder.

[Appendix 6]
The method according to Appendix 5, wherein the strong acid has a pKa of about -1.7 or less.

[Appendix 7]
The method according to Appendix 5 or 6, wherein the strong acid is sulfuric acid, nitric acid, hydrochloric acid, or any combination thereof.

[Appendix 8]
(A) (i) At least water, non-pregelatinized starch and acid are mixed to form a wet starch precursor having a water content of about 8% by weight to about 25% by weight. Acid
(1) Weak acid that does not substantially chelate calcium ions,
(2) Forming selected from the group consisting of strong acids in an amount of about 0.05% by weight or less by weight of the starch, or (3) any combination thereof;
(Ii) Feeding the wet starch precursor to an extruder; and (iii) having the wet starch with a die having a temperature of about 150 ° C. (about 300 ° F) to about 210 ° C. (about 410 ° F). Forming pregelatinized partially hydrolyzed starch by pregelatinization and acid denaturation in the extruder;
(B) The pregelatinized partially hydrolyzed starch is mixed with at least water and stucco to form a slurry;
(C) The slurry is placed between the first cover sheet and the second cover sheet to form a wet assembly;
A method for making a board, comprising (d) cutting the wet assembly into boards; and (e) drying the boards.

[Appendix 9]
The method according to Appendix 8, wherein the slurry further contains sodium trimetaphosphate.

[Appendix 10]
When using pregelatinized partially hydrolyzed starch, the amount of water that needs to be added to maintain the fluidity of the slurry at the same level as the slurry without pregelatinized partially hydrolyzed starch is prepared according to different methods. The method of Appendix 8 or 9, which is less than the increment of the amount of water required for.

Claims (9)

A method for producing pregelatinized partially hydrolyzed starch for blending into gypsum slurry used for producing gypsum board, wherein the method is (a) at least water, non-pregelatinized starch, and unmodified non-modified starch. Wet starch precursor having a water content of 8% to 25% by weight by mixing with a strong acid having a pKa of -1.7 or less in an amount of about 0.05% by weight or less based on the weight of pregelatinized starch. To make;
(B) Supplying the wet starch precursor to an extruder; and (c) delivering the wet starch to the extruder at a die temperature of 150 ° C. (about 300 ° F) to 210 ° C. (about 410 ° F). Methods that include simultaneous pregelatinization and acid denaturation in. The method according to claim 1, wherein the strong acid is sulfuric acid, nitric acid, hydrochloric acid, or any combination thereof. The method according to claim 2 , wherein the strong acid is sulfuric acid. The method according to any one of claims 1 to 3 , wherein the amount of the strong acid is 0.0001% by weight to about 0.02% by weight of the non-pregelatinized starch. The method according to claim 4 , wherein the amount of the strong acid is 0.0001% by weight to about 0.01% by weight of the non-pregelatinized starch. The method according to any one of claims 1 to 5 , wherein the method does not include a step of purifying the pregelatinized partially hydrolyzed starch and a step of neutralizing the starch. The method according to any one of claims 1 to 6 , wherein the slurry containing the pregelatinized partially hydrolyzed starch further contains sodium trimetaphosphate. The amount of water that needs to be added to maintain the fluidity of the slurry containing the pregelatinized partially hydrolyzed starch at the same level as the slurry without the pregelatinized partially hydrolyzed starch is prepared according to different methods. The method according to any one of claims 1 to 7 , which is less than the increment of the amount of water required when using the partially hydrolyzed starch. (A)
(I) At least water, the non-pregelatinized starch, and a strong acid having a pKa of -1.7 or less in an amount of about 0.05% by weight or less based on the weight of the unmodified non-pregelatinized starch are mixed. To form a wet starch precursor with a moisture content of 8% to 25% by weight;
(Ii) Feeding the wet starch precursor to an extruder; and (iii) the extrusion of the wet starch with a die having a temperature of 150 ° C. (about 300 ° F) to 210 ° C. (about 410 ° F). Simultaneous pregelatinization and acid denaturation on the machine; to form pregelatinized partially hydrolyzed starch with a gelatinization degree of 70% or higher;
(B) The pregelatinized partially hydrolyzed starch is mixed with at least water and stucco to form a slurry;
(C) The slurry is placed between the first cover sheet and the second cover sheet to form a wet assembly;
A method for making a board, comprising (d) cutting the wet assembly into boards; and (e) drying the boards.

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