TWI621633B - Biodegradable absorbent material and method of manufacture - Google Patents

Abstract

A biodegradable graft copolymer and a substantially adiabatic polymerization process for making a graft copolymer are disclosed, the graft copolymer being derived from a carbohydrate and at least one superabsorbent α,β-unsaturated carboxylic acid derivative. The disclosed process can be carried out in a variety of currently available commercial continuous reactors. The polymerization with starch has surprisingly produced a graft copolymer which is free of residual monomers and which is produced as a moist copolymer in a substantially quantitative yield. Product processing typically involves neutralization and drying as appropriate.

Description

Biodegradable absorbent material and method of producing the same

Cross-reference to related applications

The present application claims the benefit of U.S. Provisional Patent Application No. 61/268,228, filed on Jun. 9, 2009, which is hereby incorporated by reference.

This application relates to biodegradable graft copolymers useful as superabsorbent polymers and related applications and methods of making graft copolymers.

Superabsorbent polymer (SAP) is a substance that absorbs or absorbs at least 10 times its own weight of aqueous fluid and retains the inhaled or absorbed aqueous fluid at moderate pressure. The aqueous fluid that is inhaled or absorbed is taken up into the molecular structure of the SAP rather than being contained in the pores (in this case, the fluid can be eliminated by extrusion). Some specialty SAPs can absorb up to 1,000 times their weight of aqueous fluids. The present invention is directed to: (1) a graft polymerization process suitable for the preparation of biodegradable SAP and biodegradable polymers suitable for other applications; and (2) novel graft copolymers produced by such methods.

An SAP manufacturing method comprises graft-polymerizing acrylonitrile onto starch in the presence of an initiator such as a tetravalent cerium (+4) salt to form a starch graft copolymer, and saponifying the nitrile group with an alkali metal to form an alkali metal carboxylic acid. a salt and a saponified salt of a carboxyguanamine group.

However, the saponification reaction requires expensive machines and produces ammonia, which may be corrosive, costly to remove, and expensive to recycle and/or treat. Further, potassium hydroxide (KOH) was added during the saponification reaction to make the saponified starch graft copolymer mixture alkaline, and a product mixture having both viscosity and viscosity was obtained. For most applications, an acid such as hydrochloric acid, nitric acid, sulfuric acid or phosphoric acid must be added to the alkaline mixture to neutralize the excess base and the pH of the mixture is adjusted to about 7.5. Ultimately, the viscous and viscous material must be pumped into a large amount of methanol and subjected to several chopping steps to remove the dissolved salt and convert the polymer into a usable form. Disposal of the resulting waste liquid may also be expensive because the waste liquid includes potassium and ammonium salts as well as other foreign materials. More specifically, waste containing acrylonitrile may be harmful and its disposal is also relatively expensive. Separating 1 pound of polymer may require up to 3 gallons of methanol. As a result, a 10 million-pound SAP/year plant may require up to 30 million gallons of methanol per year. A loss of only 1% of the required methanol can introduce up to 300,000 pounds of methanol per year into the environment.

The most recent method described in U.S. Patent No. 7,459,501 is developed for the manufacture of SAP and includes the monomer (acrylic acid or its ester, optionally including acrylamide) in the presence of a crosslinking agent and an initiator under isothermal conditions. Graft polymerization on starch. The batch process involves combining the reactants in water, heating the mixture to about 170 °F, and maintaining the temperature for about 15 minutes. The resulting viscous material is neutralized with a base and separated after addition of a large amount of methanol to convert the viscous material into a treatable physical form. Although this method of manufacturing SAP avoids saponification, disposal of acrylonitrile, and recovery of large amounts of ammonia, it is still necessary to utilize and recover a large amount of methanol (or other lower alcohol), and the process is viscous due to the initially formed graft copolymer product. And viscous and can not be carried out in a continuous process. In the absence of alcohol in the product separation step, the polymer produced is a non-flowable product and, even in the batch process, is too viscous and viscous to be processed by currently available equipment.

There is a need for a high purity biodegradable SAP and related polymers having a range of absorbencies and other properties, and a method of making polymers from readily available starting materials with high conversion. The process will be able to be carried out in a continuous manner using currently available production equipment, directly producing a large amount of polymer and allowing it to be separated directly without the need to dispose of toxic substances or recycle large amounts of harmful gases and/or solvents. The present invention addresses these needs.

The present invention provides high purity biodegradable superabsorbent polymer products that are directly produced from readily available starting materials with minimal processing and without further purification, and one suitable for large scale commercial production in currently available commercial equipment. Method of manufacturing a product. The disclosed method does not utilize acrylonitrile, does not require a large amount of ammonia saponification reaction, and does not require a large amount of methanol or other lower alcohol to complete the treatment of the initially formed polymer viscous material.

A first aspect of the invention includes a method for forming a graft copolymer comprising: (1) combining water, a carbohydrate, at least one alpha, beta-unsaturated carboxylic acid derivative, and a catalyst to form an initiating a combination of conditions; (2) introducing the combination into a reactor having a reaction zone providing the initiation conditions; and (3) forming a graft copolymer under substantially adiabatic conditions in the reactor to obtain a free-flowing copolymer . The reaction is typically completed in about 5 minutes or less, more typically in about 3 minutes or less, and more typically in about 1 minute or less. The α,β-unsaturated carboxylic acid derivative is selected from the group consisting of acids, esters, decylamines (or hydrazines) and salts, and the catalyst is a catalyst or catalyst system capable of initiating a polymerization reaction when the combination undergoes the initiation conditions. Suitable combinations may further comprise other monomers and/or crosslinkers. The catalyst typically initiates a polymerization reaction by thermal decomposition or chemical decomposition to generate free radicals. Since the polymerization will be completed in a matter of seconds to minutes, the heat of polymerization is generated faster than it is removed, and the process becomes substantially adiabatic.

For thermally initiated polymerizations, the initiation conditions generally include temperatures at or above the activation temperature and sufficient to initiate the polymerization abruptly and allow the polymerization to proceed rapidly in an exothermic manner. For thermally initiated polymerization, the activation conditions refer to the temperature of the composition sufficient to initiate the polymerization. For chemically initiated polymerizations, the initiation conditions generally involve the presence of at least one monomer and all necessary catalyst components to initiate the polymerization reaction abruptly and to allow the polymerization to proceed rapidly in an exothermic manner.

The reaction zone of the reactor is capable of initiating a substantially adiabatic polymerization reaction by (1) rapidly increasing the combined temperature to the activation temperature of the combination or above the activation temperature of the combination or (2) initiating a chemically induced polymerization reaction. Area. Although the preferred reaction zone includes a heated surface area for the heat-induced polymerization, the reaction zone may also utilize other methods to increase the temperature of the combination, such as microwaves placed in or along the initiation zone. Radiation, infrared radiation, steam jets and the like. Chemical induction is generally achieved by combining and mixing the components required to initiate the polymerization.

Another aspect of the invention includes a method for forming a graft copolymer comprising: (1) combining water, a carbohydrate, at least one alpha, beta-unsaturated carboxylic acid derivative, and a catalyst to form a current a combination of temperature and activation temperature; and (2) bringing the current temperature of the combination to or above the activation temperature to effect a substantially adiabatic polymerization and to obtain a free flowing copolymer. The α,β-unsaturated carboxylic acid derivative is selected from the group consisting of acids, esters, decylamines (or hydrazines) and salts, and the catalyst is a catalyst or catalyst system capable of thermally decomposing or chemically decomposing to generate free radicals. Once the polymerization is initiated, it is typically completed in a reaction time of only a few seconds to a few minutes. Since the heat of polymerization is generated much faster than its removal, the process becomes substantially adiabatic. Suitable combinations may further comprise other monomers and/or crosslinkers.

Another aspect of the invention includes a method for forming a graft copolymer, the method comprising: (1) combining water, a carbohydrate, at least one alpha, beta-unsaturated carboxylic acid derivative, and a catalyst to form a combination of activation temperatures; and (b) contacting the combination with a surface heated to a temperature at or above the activation temperature to initiate polymerization and complete under less than about 5 minutes (after initiation) under substantially adiabatic conditions. The polymer is formed to give a free flowing copolymer. Suitable α,β-unsaturated carboxylic acid derivatives may be selected from the group consisting of acids, esters, decylamines (or hydrazines) and salts, and the catalyst is capable of initiating a polymerization reaction when subjected to the initiation conditions. Suitable combinations may further comprise other monomers and/or crosslinkers. Reactors capable of providing a suitable heating surface include, but are not limited to, a hot screw, a heated drum, and a belt reactor.

Another aspect of the invention includes a method for forming a graft copolymer, the method comprising: (1) combining water, a carbohydrate, at least one alpha, beta-unsaturated carboxylic acid derivative, and a first catalyst component To form a combination; and (2) to provide a second catalyst component to the combination to initiate a chemically induced substantially adiabatic polymerization and to obtain a free flowing copolymer. Suitable α,β-unsaturated carboxylic acid derivatives may be selected from the group consisting of acid, ester, decylamine (or hydrazine) and salt, and the first catalyst component can be decomposed after being combined with the second catalyst component to initiate polymerization. reaction. Suitable combinations may further comprise other monomers and/or crosslinkers.

For graft copolymers containing acidic carboxyl groups, especially SAP, the initially formed SAP can be neutralized with a base if desired. The initially formed SAP can be directly neutralized and dried in the reactor system or on the reactor system, and the resulting dried polymer is granulated, pelletized, extruded or otherwise processed prior to packaging. Heretofore, neutralization has been carried out by treating the initially formed SAP with an aqueous solution of an inorganic alkali. Preferred bases for neutralizing the initially formed SAP, if desired, include, but are not limited to, inorganic alkali metal hydroxides, carbonates, bicarbonates, and mixtures thereof.

Although any carbohydrate containing a sugar ring can be utilized according to current research, preferred carbohydrates include starch and cellulose, and starch is currently preferred. Certain carbohydrates, such as different forms of cellulose, may require pretreatment to remove lignin and/or other materials that inhibit graft polymerization prior to grafting.

Preferred monomers have at least some water solubility and include alpha, beta-unsaturated carboxylic acid derivatives such as acrylic acid, methyl acrylate, acrylamide, methacrylamide, and mixtures thereof. Similar derivatives of maleic acid and itaconic acid can also be utilized. Further, other esters of α,β-unsaturated carboxylic acid or decylamine (oxime) can be utilized in a similar manner.

Preferred catalysts suitable for use in the thermal polymerization process should have at least some water solubility and may include, but are not limited to, per-compounds such as peroxides, persulfates, and the like, and azo compounds. These catalysts are typically thermally activated at a certain initiation temperature above ambient or room temperature. Redox catalysts that can be chemically activated without heating can also be utilized. Examples of redox catalysts include peroxylates of coupling metal cations, hydrogen peroxide, glycolic acid, bisulfite, and other agents.

According to current research, the crosslinking agent is polyfunctional, and a bifunctional crosslinking agent is preferred. Suitable functional groups include, but are not limited to, alpha, beta-unsaturated dicarboxylic acid derivatives, epoxides, and combinations thereof. Preferred crosslinkers should have at least some water solubility.

Various reactors may be utilized in the thermal process, with the proviso that the reactor is capable of: (1) receiving the reactants at a temperature below the catalyst activation temperature; (2) rapidly raising the temperature of the combined reactants above The temperature at which the composition is activated; (3) rapid and nearly instantaneous polymerization to obtain a substantially adiabatic polymerization process; and (4) the newly formed solid can be moved by additional neutralization and drying steps as needed. The heat required to increase the temperature of the reactants above the activation temperature of the catalyst can be provided by various means including, but not limited to, heating surfaces, microwaves, infrared radiation, steam, and the like. Preferred continuous reactors include, but are not limited to, hot screw reactors, heated drum reactors, and belt reactors.

Preferred graft copolymers are superabsorbent and are derived from starch, acrylic acid, acrylamide and bifunctional crosslinking agents. The novel SAP materials prepared by the above process have particularly high purity (unreacted monomers less than about 0.1 ppm) and are particularly stable, generally capable of maintaining a gelatinous appearance for more than 24 hours when immersed in excess water. The isolated SAP may have a sheet form, a granular form, an extruded form or may be pelletized. The graft copolymer prepared according to such methods is typically obtained in high purity wherein the copolymer and residual moisture represent at least about 98% of the composition, more preferably at least about 99% of the composition, and more preferably at least about 99.5%. combination. For preferred methods and preferred polymers, at least about 99% of all alpha, beta-unsaturated carboxylic acid derivatives are converted. In addition, a preferred SAP having a particular shape has been shown to retain the shape for a longer period of time after being submerged in water. For example, SAP particles having a cubic shape expand and maintain the cubic shape for at least about 24 to 48 hours when immersed in water.

Further details regarding the reactants, process details, graft copolymers produced, and preferred reactor systems are provided below.

For the purposes of promoting an understanding of the claimed subject matter, reference will now be made to the specific embodiments illustrated and described in the specific language. However, it is to be understood that the invention is not intended to limit the scope of the invention, and the invention is intended to cover various modifications and other modifications and other applications of the principles of the invention as described herein.

Superabsorbent polymers have proven to be particularly effective in the agricultural industry, the diaper industry, hygiene related products, and other applications. Although the desired properties can usually be achieved, it is still difficult to prepare a biodegradable high-purity SAP in large quantities at a commercial level using renewable resources as a starting material.

The method of the present invention for producing a graft copolymer (SAP) having superabsorbent properties from a carbohydrate comprises: (1) graft-polymerizing a monomer or a monomer combination onto a carbohydrate in the presence of a catalyst to form a carbohydrate graft a copolymer wherein the polymerization is carried out under substantially adiabatic conditions; (2) crosslinking the carbohydrate graft copolymer as appropriate, for example by adding a crosslinking agent such as methylenebisacrylamide Crosslinking of the carbohydrate graft copolymer; (3) adjusting the pH of the crosslinked carbohydrate graft copolymer, such as neutralization, as appropriate; (4) isolating the crosslinked carbohydrate graft copolymer; and (5) The crosslinked carbohydrate graft copolymer is dried. Although the carbohydrate may undergo some limited grafting under strong agitation conditions or after heating without a catalyst, it is preferred that the polymerization be initiated by a catalyst.

Substantially adiabatic polymerization:

A first aspect of the invention includes a polymerization process in which one or more monomers are graft polymerized onto a carbohydrate under substantially adiabatic conditions. In this regard, the term "substantially adiabatic conditions" is intended to include conditions in which the polymerization is rapid and exothermic, and all or substantially all of the heat generated by the polymerization remains in the polymerization mixture during the polymerization. That is, substantially no attempt is made to cool the combined reactants in the reaction zone during the reaction to affect the temperature therein. Thus, the heat from the polymerization is typically produced faster than it dissipates to the surrounding region, and the temperature of the reaction mixture in the reaction zone substantially reaches the temperature resulting from the uncontrolled exotherm of the polymerization reaction. The "reaction zone" is intended to include a region that receives a combination of reactants and forms a graft copolymer therein. The preferred method of the applicant can be carried out in a variety of continuous reactor systems, requiring only controlled flow rates and initiation temperatures, and is completed in less than about 60 seconds to less than about 5 minutes after initiation of the polymerization.

In contrast, isothermal polymerization is carried out under conditions and rates at which the thermal removal of the polymerization may occur as fast as possible, thereby making it possible to maintain the temperature of the polymerization system constant by heat exchange with the surroundings of the system. Typically, the isothermal process is performed by operating a process for a specified period of time at a specified temperature. Depending on the reaction, the isothermal process can be carried out with heating, cooling, or a combination of intermittent heating and intermittent cooling.

Factors affecting the process of the substantially adiabatic polymerization include, but are not limited to, the choice of monomer, the choice of catalyst, its concentration, solvent selection (if utilized), and the time required to initiate the temperature above the activation temperature. The activation temperature of a particular reaction mixture is the temperature at which the mixture will be initiated and is one of the properties of the particular reaction mixture. The initiation temperature for a particular process is the temperature at which the reaction mixture is subjected to initiate a thermally induced polymerization reaction and is associated with that particular process. Initiating temperature Activation temperature.

The graft polymerization process carried out under substantially adiabatic conditions has provided the following advantages: (1) the reaction is rapid and may be almost instantaneous; (2) the monomer is completely converted to obtain a polymer substantially free of residual monomers; (3) The polymer is generally non-viscous and can be directly transferred via production equipment in the absence of organic solvents or other processing aids; (4) the yield is substantially quantitative, and no by-products/impurities are obtained. Product; (5) The product can be directly isolated without further purification except for drying; (6) no waste stream or by-product gas is produced except for water vapor; (7) the process can be easily adapted to a continuous process and scaled up to Industrial level; (8) when carried out in a continuous process, the method avoids uncontrolled polymerization of a large amount of the reactant-containing material; and (9) the process can be carried out in an aqueous medium containing no flammable solvent.

Reactants, reagents and catalysts:

Another aspect of the invention includes reactants, reagents, and catalysts for forming a carbohydrate-based polymer, as well as the desired properties of the polymer. Since the carbohydrate matrix is typically the major component of the grafted polymer, its cost, availability, and sensitivity to graft polymerization are additional important factors. For these reasons, starch and cellulose are preferred substrates. Starch has proven to be a preferred substrate due to its cost, availability and reactivity and due to the range of physical properties that its graft copolymers can achieve.

Suitable bases include starch, fine flour and lotus root starch. More specifically, exemplary starches include natural starch (e.g., Pure Food Powder (manufactured by AE Staley), waxy corn starch (Waxy 7350, manufactured by AE Staley), and wheat starch (Midsol 50, manufactured by Midwest Grain Products). ), potato starch (Avebe, manufactured by AE Staley)), dextrin starch (for example, Stadex 9, manufactured by AE Staley), polydextrose starch (for example, Grade 2P, manufactured by Pharmachem), corn flour, peeled yucca , unpeeled yucca root, oatmeal, banana powder and tapioca flour. Starch may be gelled to provide optimum absorbency. An exemplary starch is gelatinized corn starch.

Monomers suitable for use in the substantially adiabatic processes described herein include alpha, beta-unsaturated carboxylic acids and derivatives thereof (collectively referred to as alpha, beta-unsaturated carboxylic acid derivatives). The α,β-unsaturated carboxylic acids may include, but are not limited to, acrylic acid, itaconic acid, and maleic acid. Suitable derivatives of the α,β-unsaturated carboxylic acid may further include, but are not limited to, decylamine (and hydrazine), esters and salts. Preferred α,β-unsaturated carboxylic acid derivatives include, but are not limited to, acrylic acid, methacrylic acid, acrylamide, methacrylamide, and/or 2-acrylamido-2-methyl-propane sulfonate. Acid (AMPS). Other derivatives and/or combinations of the monomers listed above and other unlisted monomers may also be utilized.

In order to prepare certain graft polymers, it may be desirable to use a single monomer, such as acrylic acid. In order to prepare other graft polymers, it may be desirable to use a combination of monomers such as acrylic acid and acrylamide grafted onto a carbohydrate substrate. In order to prepare other graft polymers, it may be desirable to use a monomer mixture comprising additional monomers such as 2-acrylamido-2-methyl-propane sulfonic acid. For other graft polymers, especially SAP, the monomer mixture may require the use of a combination of monomers containing one or more crosslinkers.

The addition of acrylamide to the monomer mixture containing acrylic acid appears to help to form the resulting graft polymer. For example, a preferred weight ratio of acrylic acid to acrylamide may be about 2:1. Alternatively, the ratio of acrylic acid to acrylamide may also be in the range of 9:1 and above 9:1. The graft polymer can also be prepared using acrylic acid alone or with acrylic acid and other comonomers but without acrylamide.

A crosslinking agent can be added to the mixture to form a crosslinked graft copolymer. It may be desirable to crosslink the graft copolymer to improve the properties of the polymer. For example, if the uncrosslinked graft copolymer is dissolved in an aqueous fluid, crosslinking can minimize and/or prevent dissolution of the polymer. Similarly, the softening point of the graft copolymer can be increased by crosslinking and increasing the degree of crosslinking. In general, the amount of crosslinker added is inversely proportional to the absorbance of the resulting product. Exemplary crosslinkers include: glycerides; diepoxides; diglycidyl; cyclohexanedioxane; methylenebis acrylamide; bishydroxyalkylguanamines such as bishydroxypropyl hexamethylenediamine; Such as urea-formaldehyde and melamine-formaldehyde resins; isocyanates, including diisocyanates or triisocyanates; epoxy resins, typically in the presence of a base catalyst; and derivatives and mixtures thereof. Two preferred crosslinking agents include glycidyl methacrylate and methylene bis acrylamide.

Catalysts useful in substantially adiabatic graft polymerization include catalysts and catalyst systems typically used in free radical polymerization. Preferred catalysts are heat activated and have at least some water solubility. Particularly preferred catalysts include peroxides, including hydrogen peroxide, tributyl peroxide and acetoxy peroxide; persulfates including, but not limited to, ammonium persulfate and alkali metal persulfates; and azo compounds, These include, but are not limited to, 2,2'-azobis(2-methylamidinopropane)-dihydrochloride. Catalysts that can be activated at ambient temperatures, such as redox catalyst systems, can also be utilized. For example, ammonium persulfate or potassium persulfate can be coupled with hydrogen peroxide, iron salts, glycolic acid, bisulfite, and other components to obtain a catalyst system capable of initiating polymerization at ambient temperatures below the decomposition temperature of the catalyst.

Alternative methods of initiating polymerization and crosslinking can also be employed. For example, the solid SAP product can be crosslinked by irradiation, such as exposure to gamma or x-ray electromagnetic radiation or electron beams and the like. Irradiation promotes cross-linking of the graft copolymer by generating a radical in the copolymer chain. In some applications, a crosslinked copolymer chain can be formed using an annealing or melting process after irradiation. In addition, it may be desirable to perform an irradiation treatment in an atmosphere that is relatively free of oxygen.

Method specific example:

1 is a flow diagram illustrating one exemplary embodiment of a process 1 for producing a graft copolymer derived from an alpha, beta-unsaturated carboxylic acid derivative and a carbohydrate as described herein under substantially adiabatic conditions. When the selected method utilizes starch, SAP having particularly high purity and high absorbency can be produced. Other variations of the described methods can be made by those skilled in the art using the above reactants and catalysts in accordance with the following reaction methods. According to the invention, the reactants are combined with the catalyst or catalyst component initially in a manner that avoids the initiation conditions.

For thermally initiated polymerizations, the initiation conditions generally include temperatures above the activation temperature at which the polymerization can be initiated abruptly and the polymerization proceeds rapidly in an exothermic manner. Both the properties of the resulting graft polymer and the rate of polymerization are affected by the extent to which the initiation temperature exceeds the activation temperature. According to studies conducted to date, when the initiation temperature is about 10 °F to about 15 °F higher than the activation temperature, copolymers derived from starch have obtained excellent properties including color and absorbance. The activation temperature can be affected by various factors including, but not limited to, the reactivity of the monomer, the decomposition temperature of the catalyst, the monomer and catalyst concentration, the solvent, the polymerization inhibitor present in the monomer, and the presence or absence of oxygen. Those skilled in the art of graft copolymer formation can readily optimize specific polymerization reactions by modifying such variables.

For chemically induced graft polymerization, the reactants and the first catalyst component are combined at a temperature below the heat-induced activation temperature. The second catalyst component is combined and thoroughly mixed with the reactant comprising the first catalyst component to create the initiation conditions and to initiate the polymerization reaction abruptly. The initiated polymerization is then carried out under substantially adiabatic conditions. The rate of chemically induced polymerization may affect the properties of the resulting polymer and may be affected by the temperature at which the polymerization is initiated and the amount of each catalyst component. Depending on the temperature at which the chemically induced polymerization is initiated and the exothermic nature of the polymerization process and the catalyst system chosen, if the temperature of the polymerization mixture rises above the activation temperature of the system, the chemically induced polymerization can be carried out at a later stage. In addition, it becomes heat induction. More specifically, thermal activation may occur if the polymerization mixture has an activation temperature and the exothermic nature of the polymerization causes the temperature of the mixture to exceed its activation temperature. Persulfate is an example of a catalyst or catalyst component capable of undergoing thermal or chemical activation after combination with a second catalyst component. The manner in which the two catalyst components become components of the reactant combination is generally not critical, for example, catalyst component 1 and catalyst component 2 can be reversed.

Gather Compound:

After the graft copolymer is formed, its pH can be adjusted to the desired value for a particular application by the addition of a base. For example, the crosslinked graft copolymer can be neutralized to convert the carboxyl group to a salt, thereby affecting the properties of the neutralized polymer. Depending on the use of the polymer, alternative pH values may be required with alternative bases. For SAP applications including human exposure, control is safe and suitable for contact properties. For agricultural applications, potassium and/or ammonium salts may be advantageous, and the choice of salt may depend on the type of soil and the type of crop to be planted. For most agricultural applications, the desired pH will typically range from about 6.0 to about 8.0. Depending on the requirements of a particular agricultural application, the desired pH may be greater or less than this range. For some specific examples, pH adjustment may not be necessary. For example, if the acid form of the polymer provides the desired properties, or if the graft copolymer is prepared as a salt of an alpha, beta-unsaturated carboxylic acid, no pH adjustment is necessary.

The resulting pH adjusted graft copolymers produced by the methods described herein can then be directly isolated after some degree of pre-drying or without pre-drying. An exemplary separation process involves pre-drying in a reactor system, removing it from the reactor system, followed by further drying and processing as needed. If desired, the dried graft copolymer can then be pelletized according to a pelletizing method known to those skilled in the art. The graft copolymer prepared in accordance with the present invention can be isolated directly without the use of methanol, other lower alcohols and/or other processing aids.

The method described herein directly yields a pH which does not contain foreign salts and does not escape ammonia, as compared to an alternative method of producing a graft copolymer such as SAP which is required to be subjected to a saponification step (described in the [Prior Art] section). A modified graft copolymer reaction material (crosslinked or uncrosslinked). In addition, the resulting graft copolymer is non-viscous but flowable, making it possible to maintain a completely aqueous system, avoiding the use of anti-adhesives to prevent sticking and avoiding contamination by alcohol. The use of methanol or similar alcohols can significantly increase the cost of manufacturing SAP because the recovery and disposal of methanol (related lower alcohols) can be relatively expensive. In addition to cost, the use of alcohol also introduces safety and environmental issues. The use of an anti-adhesive agent increases processing costs and material costs, and obtains a graft copolymer additionally containing an anti-adhesive. The present invention provides a method of avoiding such defects.

Reactor selection:

The following disclosure is provided to illustrate examples of reactors that can undergo substantially adiabatic graft polymerization, and is not intended to limit the breadth of the invention, nor is it intended to limit the disclosed process to the particular reactor. The reactor illustrated includes a hot screw (Fig. 2), a heated drum reactor (Fig. 3) and a belt reactor system (Fig. 4).

Figure 2 illustrates a hot screw reactor system 50 suitable for carrying out substantially adiabatic graft polymerization. A double hot screw (not illustrated) is preferred due to its inherent cleaning ability. The system includes a source of reactants 53 capable of delivering a suitable reaction mixture to polymerization reaction zone 52 maintained at an initiation temperature to initiate polymerization reaction abruptly upon introduction of the reactants. Reactant source 53 may be a vessel designed to maintain the reactants at a temperature below the initiation temperature and activation temperature or a mixing device such as a static mixer that passes through the reaction stream to the polymerization zone 52 . The solid formed in the polymerization zone 52 is moved in the direction of the neutralization zone 54 by the extrusion screw 57 , wherein the base can be introduced into the system 50 from the alkali reservoir 58 . The neutralized solids from the neutralization zone 54 are further moved into the drying zone 56 by the extrusion screw 57 , wherein the moisture is removed via the venting opening 55 connected to the vacuum source. By regulating the time the polymer of the drying zone 56, wherein the temperature and the degree of vacuum maintained in the discharge of the polymer obtained was dried to the drying zone of 56. The solids exiting reactor system 50 can be further dried, granulated, and sized as needed.

Figure 3 illustrates a heated drum reactor polymerization system 60 . Reactant 63 comprising carbohydrates, monomers, and catalyst can be delivered from reactant source 72 to polymerization reaction zone 64 of heating drum 61 via delivery system 62 , wherein the polymerization reaction begins abruptly to form a graft copolymer. Reactant source 72 may be a mixing device (e.g., a static mixer) that contains a reservoir or reactant of the combined reactants to effect its combination and mixing. The surface of the heated drum reactor 61 is maintained at an initiation temperature sufficient to suddenly initiate a substantially adiabatic polymerization. As the heated drum 61 rotates, the newly formed polymer passes through a neutralization zone 66 where the polymer is contacted with a base 65 delivered from a neutralizing alkali source 68 . As the heated drum 61 continues to rotate, the neutralized polymer enters the drying zone 73 where moisture is removed from the solids. Vent vent 67 can be used to move air over the wet polymer to promote drying. As the heated drum continues to rotate, the dried or partially dried solids reach the positioned cutter 71 to remove substantially all of the solids 70 attached to the heated drum 61 , thereby collecting the solids in the hopper 69 . The hopper 69 can be replaced with a conveyor belt (not shown) or other collection mechanism to aid in the removal of solids.

Figure 4 illustrates a belt reactor system 100 suitable for use in a substantially adiabatic graft polymerization process. Reactant 102 can be delivered from reactant source 113 to polymerization zone 110 maintained at the initiation temperature to suddenly form a heated ribbon of solid polymer 101 . The initiation temperature can be maintained by directly heating the belt surface, by infrared radiation, by microwave radiation, or by any other conventional method. The formed polymer is transferred from the zone from the polymerization zone 110 into the neutralization zone 111 , wherein the base 104 can be added from the neutralization source 103 to form the neutralized polymer 105 . Further movement of the heated belt causes the neutralized polymer 105 to be moved into the drying zone 112 where moisture is removed by evaporation. Water removal can be facilitated by traversing the air through the wet solids, additional warming, or any other conventional drying method. As the dried or partially dried solid 106 is removed from the drying zone 112 , contact with the cutter 107 causes the polymer 108 to be removed and collected in the vessel 109 . The container 109 can be replaced with a conveyor belt or other automated component to aid in the collection of the formed polymer. Suitable for the belt reactor can also receive the combined small droplets, thereby affecting the polymerization and obtaining a polymer in the form of a paste.

Appropriate positioning of the components associated with hot screw reactor 50 , heated drum reactor 60, and belt reactor 100 can be readily determined by those skilled in the art for specific graft copolymerization, neutralization, and drying. The locations provided for the various components in Figures 2, 3, and 4 are provided for illustrative purposes only and are not intended to be considered as optimal locations. Moreover, the examples of reactors provided herein are for illustrative purposes, and the examples are not intended to limit any claimed method to a particular reactor unless such limitations are obvious.

Example:

The following examples describe the graft polymerization of a particular carbohydrate with acrylic acid under substantially adiabatic conditions with or without acrylamide, with or without a crosslinking agent. The reaction mixture is formed by: (1) forming (a) a combination of water and acrylic acid and (b) a combination of starch, acrylamide, a crosslinking agent and a catalyst, and mixing the two combinations; or (2) The remaining components are added by a combination of water and starch formation and agitation. The aqueous starch mixture is typically stirred for 1 to 2 hours until homogeneous, followed by a grafting operation. At an industrial level, a jet cooker utilizing steam sparging can be used to facilitate the preparation of the water starch mixture. Examples of graft polymerization in a stainless steel tube, on a heated metal surface (heated long handle pan), in a vessel suspended in a water bath, and in a microwave oven are provided. The monomer content and absorbance of the formed polymer were measured. Procedures for adapting such methods to continuous reactors, including hot screws, heated drum reactors, and belt reactors, are also provided. Embodiments of substantially adiabatic polymerization in a heated hot screw, on a heated drum reactor, and on a belt reactor are also provided.

The absorbance (water) of the graft copolymer is determined by the following steps: drying the copolymer sample; determining the moisture content of the dried sample; weighing 0.5 g of the sample; adding about 700 mL of water; and after about 4 hours The mixture was poured into a 325 mesh screen to remove excess water. The residual surface water was removed by gentle wiping and the fully hydrated sample was weighed. The difference between the hydration weight of the sample and its dry weight (which has been corrected for any moisture remaining in the dry sample) is determined and used to determine the absorbance of the sample.

Example 1-8

An aqueous solution of the reaction mixture containing starch, acrylic acid, acrylamide, a crosslinking agent, and a catalyst is prepared. The reaction mixture is added to a stainless steel tube heated to an initiation temperature to initiate polymerization, and the initiated polymerization is carried out under substantially adiabatic conditions in the steel tube. Heating is provided in a heating mantle or water bath. Use a water bath to provide more precise temperature control. The polymer is formed in a quantitative yield. The selected polymer was neutralized with an aqueous solution of potassium hydroxide and its absorbance was measured. Table I provides details of Reactions 1 through 8. Each polymerization is completed in less than about 5 minutes to obtain a solid, and some polymerizations are completed in less than about 1 minute. The lack of agitation in the stainless steel tube causes a slight delay in the polymerization in the center of the tube. In addition, reactions conducted at higher temperatures have shown that if the polymer is exposed to higher temperatures for longer than necessary, some discoloration may occur due to overheating. Although the polymer sample obtained generally does not contain any acrylic odor, some slight acrylic odor can be detected from the headspace above a stored polymer sample, which was obtained from the early use of a non-stirred tubular reactor. Operation. A tubular reactor containing an auger or similar agitation mechanism can improve the agitation of the reaction mixture, promote heat transfer to reach the initiation temperature, and further move the resulting solid through the tube. Better mixing and heat transfer can further reduce any traces of acrylic acid remaining in the solids. Similar graft polymerizations can be carried out with other carbohydrates and alpha, beta-unsaturated carboxylic acid derivatives described herein.

Example 9

A reaction mixture containing 1000 g of water, 100 g of starch, 100 g of acrylic acid, 50 g of acrylamide, 0.5 g of glycidyl methacrylate, and 0.5 g of ammonium persulfate was prepared. A portion of the reaction mixture (about 1/3) was placed in a microwave oven and heated on a high fire to quickly reach the initiation temperature (about 30 seconds), at which time the microwave oven was turned off. The solid formed was neutralized with KOH and the absorbance was determined to be 111 . No residual acrylic acid was detected by the sense of smell, and the iodine solution did not decolorize after contact with the obtained polymer.

Example 10

A reaction mixture containing 1000 g of water, 100 g of starch, 125 g of acrylic acid, 25 g of acrylamide, 0.5 g of glycidyl methacrylate, and 0.25 g of ammonium persulfate was prepared. A portion of the reaction mixture having an initial temperature of about 145 °F was poured onto a metal stalk pan heated in a water bath maintained at about 180 °F. The rapidly formed polymer was cooled and neutralized with potassium hydroxide, and its absorbance was determined to be 360. Residual acrylic acid could not be detected. Similar results were obtained by adding a similar polymerization mixture to an electric oven preheated to about 375 °F, but the polymerization took place much faster.

Example 11-17

An aqueous solution of a reaction mixture containing starch, acrylic acid, acrylamide, a crosslinking agent (glycidyl methacrylate), and a catalyst is prepared. Example 15 additionally contained a significant amount of 2-acrylamido-2-methylpropane sulfonic acid (AMPS). The reactants are placed in a vessel located in a water bath maintained at the initiation temperature. Once the activation temperature is reached and exceeded, the polymerization is initiated, resulting in an increase in temperature and the formation of a solid. The odorless and iodine test as described above demonstrates that there is no residual acrylic acid in the polymer. The polymer yield is substantially quantitative. A portion of the polymer was neutralized with potassium hydroxide or sodium bicarbonate, and the selected samples (13 and 14) were additionally rinsed with isopropanol and dried prior to testing to determine the absorbency of the polymer. This method can also be used to prepare graft polymers without crosslinking agents. Isopropanol rinses were only used to determine the possible effect on polymer absorbance. The results are summarized in Table II below.

Example 18-22

An aqueous solution of a reaction mixture containing starch, acrylic acid, acrylamide, a crosslinking agent (methylenebisacrylamide), and a catalyst (ammonium persulfate) is prepared. The reactants are placed in a vessel located in a water bath maintained at the initiation temperature. Once the activation temperature is reached, the polymerization is initiated, causing the temperature to rise and form a solid. The odorless and iodine test as described above demonstrates that there is no residual acrylic acid in the polymer. The polymer yield is substantially quantitative. A portion of the polymer was neutralized with potassium hydroxide, sodium bicarbonate or potassium carbonate, followed by testing to determine the absorbency of the polymer. The results are summarized in Table III below.

Example 23

The graft polymerization was carried out in a twin hot screw reactor. Suitable reactors may be single screw reactors or twin screw reactors and may vary in size and configuration. For purposes of illustration, a reactor having a diameter of about 24 angstroms and a length measurement of about 20 angstroms has been selected. The twin hot screw assembly is equipped with the fitting illustrated in Figure 2 of the single screw reactor. The area and accessory names utilized in Figure 2 are used in this embodiment. As illustrated, the reactor is equipped with a reactant source 53 , a neutralization source 58, and a venting port 55 that reaches the vacuum source. During the polymerization described below, the twin screw operates at a rate of about 2.25 Torr/min and the polymerization reaction zone 52 is heated to at least about 165 °F to about 180 °F. The polymerization zone 52 is from about 2 Torr to about 4 Å long, the neutralization zone 54 is from about 1 Torr to about 2 Å long, and the drying zone 56 is from about 14 Torr to about 17 Å long.

A polymerization mixture containing 10,000 kg water, 1,120 kg starch, 1.250 kg acrylic acid, 350 kg acrylamide, 2.5 kg methylene bis decyl amide, and 7.5 kg ammonium persulfate was passed through the reactant source at a rate of about 20 gallons per minute. 53 is delivered to the polymerization zone 52 of the hot screw. Once inside the twin hot screw, the polymerization is initiated and completed in about 1 to 4 minutes. As the hot screw moves the wetting solids from the polymerization zone 52 into the neutralization zone 54 , a sufficiently dilute aqueous potassium hydroxide solution is delivered from the neutralization source 58 to the twin screw to mix and neutralize the carboxyl groups of the polymer and obtain about 7.5 pH value. As the twin screw continues to move forward, the neutralized solids are transferred into the drying zone 56 where the wetting polymer is subjected to reduced pressure with continued heating to promote drying. The desired degree of dryness can be achieved by varying the length of the drying zone, varying the vacuum applied to the venting opening 55 , varying the rate of rotation of the screw 57 , and increasing the temperature of the drying zone 56 . If desired, the flowable solid exiting the twin screw reactor can be further dried, granulated and/or sized directly for any particular application without any further purification or processing. When operated in this manner, the dual hot screw reactor 50 can produce about 21 million pounds of copolymer during about 300 days of operation.

Example 24

The graft polymerization was carried out on a heated drum reactor 60 (Fig. 3). The reactor can vary in size and configuration, but for illustrative purposes, a reactor having a heated drum measuring about 4 Torr x about 9 Torr has been selected to achieve a usable surface area of about 91 square feet and about 10 The circumference of a linear ft. As illustrated in Figure 3, the reactor is equipped with a reactant source 72 , a neutralization source 68 , a reactor vent 67, and a cutter/scraper device 71 . During operation, the heated drum rotates counterclockwise at a rate that completes one revolution approximately every 8 to 9 minutes.

The polymerization mixture containing 1000 kg water, 112 kg starch, 125 kg acrylic acid, 25 kg acrylamide, 0.25 kg glycidyl methacrylate and 0.5 kg ammonium sulfate is heated to about 150 °F and at about 0.9 gallons per minute. The rate is from the reactant source 72 by heating the drum to the polymerization zone 64 . The surface of the heated drum is maintained at a temperature of from about 170 °F to about 200 °F. The polymer is formed in less than about 30 to 45 seconds and the drum is coated with a solid. As the drum and is moved in the direction of the source 68, and ejected from the source 68 sufficiently dilute alkali aqueous potassium hydroxide solution coated over the surface of the drum, and to carboxyl groups of the polymer, and obtain a pH of about 7.5. As the drum containing the neutralized polymer continues to rotate, the wetting polymer passes through the drying zone 73 where air passes over the warming polymer to promote drying. As the drum continues to rotate, the dried or partially dried polymer contacts the cutter/blade 71 , which removes the polymer from the drum and causes it to fall into the hopper 69 . The resulting free flowing polymer can be used as received or further dried without any additional purification steps or treatment. In addition, the physical form of the copolymer formed can be altered to suit a particular application.

When operated in this manner, heated drum reactor 60 can produce about 2.6 pounds of final product per minute, and when operated at 80% of the operating time, about 1.1 million pounds of copolymer can be produced per year.

Example 25

The graft polymerization was carried out on a belt reactor 100 (Fig. 4). The reactor can vary in size and configuration, but for illustrative purposes, a reactor having been measured to be about 4 inches wide by about 30 inches long has been selected to provide a working upper surface area of about 120 square feet. As illustrated in Figure 4, the reactor is equipped with a reactant source 113 , a neutralization 103, and a cutter/scraper device 107 . During operation, the belt rotates clockwise at a rate of about 3 呎/min. The polymerization zone of the belt can be heated by various known methods for heating the zone of the belt reactor, including a microwave source (not shown). The reactor can be equipped with a roller (not shown) to level the reaction mass as necessary.

The polymerization mixture containing 1000 kg water, 112 kg starch, 125 kg acrylic acid, 25 kg acrylamide, 0.25 kg glycidyl methacrylate and 0.5 kg ammonium sulfate is heated to about 150 °F and is about 3 to 4 gallons / The rate of minutes is passed from the reactant source 113 through the polymerization zone 110 of the belt and the belt is moved forward at a rate of about 3 Torr/min. The polymerization zone 110 is heated and maintained at a temperature of from about 165 °F to about 180 °F. The polymer is formed in less than about 1 to 2 minutes and the tape is coated with a solid. With the belt in the direction of movement and source 103, 103 from the discharge source and the base with dilute aqueous potassium hydroxide solution sufficient across the surface of the belt through the coating, and the carboxyl groups of the polymer, and obtain a pH of about 7.5. The wet polymer passes through the drying zone 112 as the belt carrying the neutralized polymer continues to advance. The drying zone 112 can be maintained at elevated temperatures at additional elevated temperatures, and the air stream can pass over the warming polymer to promote drying. As the belt continues to advance, the polymer contacts the cutter/blade 107 , which removes the polymer and causes it to fall into the polymer collector 109 . The resulting free flowing polymer can be used as received or further dried without any additional purification steps or treatment. In addition, the physical form of the copolymer formed can be altered to suit a particular application. When operated in this manner, the belt reactor 100 can produce about 10.8 pounds of final product per minute, and when operated at 80% of the operating time, about 4.5 million pounds of copolymer can be produced per year.

Example 26

A double thermal screw reactor (further equipped with a second reactant delivery system) utilized in Example 23 can be utilized to prepare a graft copolymer based on a redox catalyst system such as ammonium persulfate and sodium metabisulfite. The first reaction mixture contains 10,000 kg of water, 1,120 kg of starch, 1,250 kg of acrylic acid, 350 kg of acrylamide, 2.5 kg of methylenebis acrylamide, and 7.5 kg maintained at ambient temperature (about 68 °F to about 86 °F). Ammonium persulfate, and the second reaction mixture contained 2 kg of sodium metabisulfite in 50 gallons of water. When the two reaction mixture streams are added proportionally to the unheated polymerization zone 52 of the twin hot screw, the stream is mixed and the polymerization is chemically initiated and adiabatically completed. When passing through polymerization zone 52 , the temperature of the polymerization mixture will typically increase by from about 15 °F to about 30 °F. As in Example 24, the formed polymer can be neutralized and dried. Drying can be promoted by additionally heating the drying zone 56 .

If the first reaction mixture is preheated to about 150 °F prior to mixing with the second reaction mixture, the exothermic polymerization can be initiated chemically, and as the temperature increases to the activation temperature, the polymerization can additionally become thermally initiated. The polymerization can be carried out by chemical initiation polymerization, thermal initiation polymerization, and combinations thereof using various techniques.

Example 27

A sample containing 30 g of cellulose, 125 g of acrylic acid, 25 g of acrylamide, 0.25 g of methylenebis acrylamide was combined with 0.5 g of ammonium persulfate in 1000 g of water and subjected to 186 provided by a water bath. The initiation temperature of °F. The adiabatic polymerization carried out obtains a cellulose-based graft copolymer in a manner similar to the polymerization carried out with starch.

Example 28

The hydrated sample of the graft copolymer prepared in Example 11 was exposed to wild microorganisms present in the surrounding air and maintained under hydration conditions for 7 days, after which time microbial growth on the surface of the material was observed. After about 100 days in total, microbial growth increased and the copolymer sample degraded, demonstrating its sensitivity to biodegradation.

The present invention has been described and described in detail in the drawings and the foregoing description of the invention All changes, modifications, and equivalents within the spirit of the invention as described herein and/or as defined by the appended claims. In addition, all publications cited herein are indicative of the technical skill of the art and are hereby incorporated by reference in their entirety in their entirety in their entirety herein

1‧‧‧ method

2‧‧‧Graft polymerization step

3‧‧‧pH adjustment steps

4‧‧‧Water removal steps

5‧‧‧granulation step

6‧‧‧ drying step

7‧‧‧ screening step

50‧‧‧hot screw reactor system

52‧‧‧Polymerization zone

53‧‧‧Resources source

54‧‧‧Zhonghe District

55‧‧‧ venting holes

56‧‧‧Drying area

57‧‧‧Extrusion screw

58‧‧‧alkali reservoir

60‧‧‧Heating drum reactor polymerization system

61‧‧‧Heating drum or heated drum reactor

62‧‧‧ delivery system

63‧‧‧Reactants

64‧‧‧Polymerization zone

65‧‧‧ alkali

66‧‧‧Neighborhood

67‧‧‧Exhaust

68‧‧‧Neutral alkali source

69‧‧‧ hopper

70‧‧‧ solid

71‧‧‧Tools/Scraper/Scraper

72‧‧‧Reaction source

73‧‧‧Drying area

100‧‧‧Band reactor system

101‧‧‧Solid polymer

102‧‧‧Reactants

103‧‧‧ neutralized source

104‧‧‧ alkali

105‧‧‧ neutralized polymer

106‧‧‧Dry dried or partially dried solid

107‧‧‧Tools/Scraper/Scraper

108‧‧‧ polymer

109‧‧‧Container/Polymer Collector

110‧‧‧Polymerization zone

111‧‧‧Zhonghe District

112‧‧‧Drying area

113‧‧‧Resources source

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a flow chart illustrating an illustrative embodiment of a process for making a graft copolymer product.

2 is a partially cutaway cross-sectional side view of a block diagram of one embodiment of a hot screw reactor system suitable for making a graft copolymer of carbohydrates.

3 is a side view of a combined block diagram of one embodiment of a heated drum reactor system suitable for making a graft copolymer of carbohydrates.

4 is a partially cutaway cross-sectional side view of a block diagram of one embodiment of a belt reactor system suitable for making a graft copolymer of carbohydrates.

Claims (24)

A method for forming a graft copolymer comprising: (a) combining water, a carbohydrate, at least one α,β-unsaturated carboxylic acid derivative, and a catalyst to form a combination having thermally initiated polymerization conditions; (b) introducing the combination into a reactor having a reaction zone providing thermally induced polymerization conditions; and (c) thermally initiating polymerization in the reactor under substantially adiabatic conditions to form graft copolymerization Wherein the α,β-unsaturated carboxylic acid derivative is selected from the group consisting of acids, esters, guanamines and salts and the catalyst is capable of initiating a polymerization reaction when subjected to initiation conditions. The method of claim 1, wherein the introducing the combination into a reactor having a reaction zone providing the initiating condition comprises providing a thermally initiated polymerization reaction condition selected from a heated surface, selected from a heated surface, steam, A group consisting of microwave radiation, infrared radiation, and combinations thereof. The method of claim 1, wherein the combination is introduced into a reactor having a reaction zone providing thermally initiated polymerization conditions, comprising providing a reactor selected from the group consisting of a hot screw, a heated drum reactor, and a belt reactor. Group of reactors. The method of claim 1, wherein introducing the combination into a reactor having a reaction zone providing the initiation conditions comprises introducing the combination into a reactor having a reaction zone maintained at an initiation temperature. The method of claim 1, wherein the combination comprises: (a) combining a carbohydrate selected from the group consisting of starch and cellulose (b) combining acrylic acid; and further comprising (c) combining a crosslinking agent. The method of claim 5, wherein the combining further comprises combining acrylamide. The method of claim 1, wherein forming the graft copolymer comprises converting the alpha, beta-unsaturated carboxylic acid derivative to greater than about 99%. A method for forming a graft copolymer comprising: (a) combining water, a carbohydrate, at least one α,β-unsaturated carboxylic acid derivative, and a catalyst to form a combination having a current temperature and an activation temperature; b) bringing the current temperature sufficiently above the activation temperature to thermally initiate a substantially adiabatic polymerization and obtaining a free-flowing copolymer; wherein the alpha, beta-unsaturated carboxylic acid derivative is selected from the group consisting of acids, esters, and decylamines a group of sputum, salt and salt. The method of claim 8, wherein the combination further comprises combining a crosslinking agent. The method of claim 9, wherein the combined carbohydrate comprises combining a carbohydrate selected from the group consisting of starch and cellulose; and combining at least one α,β-unsaturated carboxylic acid derivative, including a combination derived from acrylic acid, An α,β-unsaturated carboxylic acid derivative of a group consisting of maleic acid and itaconic acid. The method of claim 10, wherein the combining at least one of the α,β-unsaturated carboxylic acid derivatives comprises a combination of acrylic acid. The method of claim 11, wherein the combined carbohydrate comprises a combined starch, and combining the at least one alpha, beta-unsaturated carboxylic acid derivative further comprises combining acrylamide. For example, the method of claim 12, wherein the combination is further The crosslinking agent comprises a crosslinking agent selected from the group consisting of N,N'-methylenebis(meth)acrylamide and glycidyl methacrylate. The method of claim 13, wherein the combined catalyst comprises a combination of a catalyst selected from the group consisting of peroxides, persulfates, and azo compounds. The method of claim 14, wherein the combined starch comprises a combination selected from the group consisting of natural starch, waxy corn starch, wheat starch, potato starch, dextrin starch, corn flour, peeled yucca root, unpeeled yucca root Starch of a group consisting of oatmeal, banana powder and tapioca flour. The method of claim 15, wherein the bringing the current temperature sufficiently above the activation temperature comprises heating the combination to at least about 180 °F. The method of claim 8, further comprising the step of neutralizing the graft copolymer. The method of claim 17, further comprising the step of drying the graft copolymer to directly obtain a flowable solid. The method of claim 8, wherein the current temperature sufficiently exceeds the activation temperature occurs in the hot screw reactor. The method of claim 14, wherein the current temperature is sufficiently exceeded to exceed the activation temperature in the heated drum reactor. The method of claim 14, wherein the current temperature sufficiently exceeds the activation temperature occurs on the belt reactor. The method of claim 21, wherein the belt reactor is capable of receiving small droplets of the combination and obtaining a polymer in the form of a paste. A method for forming a graft copolymer comprising: (a) combining water, a carbohydrate, at least one alpha, beta-unsaturated carboxylic acid Derivatives and catalysts to form a combination having an activation temperature; (b) contacting the combination with a surface heated to a temperature at or above the activation temperature to initiate polymer formation and less than about under substantially adiabatic conditions The polymer formation is completed within 5 minutes to obtain a free-flowing copolymer; wherein the α,β-unsaturated carboxylic acid derivative is selected from the group consisting of acids, esters, decylamines and salts, and the catalyst is at or high The polymerization can be initiated at the temperature of the activation temperature. A graft copolymer prepared by the method of any one of claims 1 to 23.