Starch-based adhesive compositions and methods of production

Abstract

Adhesive compositions and methods of producing thereof are disclosed herein. The compositions include a mixture of water, thermally treated starch, and glyceride. The water is present from about 0% or more to about 20% or less w / w, the thermally treated starch is present from about 64% or more to about 99.5% or less w / w, and the glyceride is present from about 0.4% or more to about 20% or less w / w. This mixture may be blended with additional water to produce a flowable adhesive with improved visco-stability.

Description

[0001] STARCH-BASED ADHESIVE COMPOSITIONS AND METHODS OF PRODUCTION TECHNICAL FIELD

[0002] This disclosure relates to adhesive compositions and, more particularly, to starch-based adhesives. The disclosure further relates to starch-based adhesives used in direct and indirect food contact applications.

[0003] BACKGROUND

[0004] Starch-based adhesives are widely used in the packaging and lumber industries. These adhesives are considered favorable for manufacturing cartons, corrugated boxes, wood-based composites, and the like due to their cost-effectiveness, natural origins, and renewability. In some applications, manufacturers prepare the adhesives on-site by cooking with caustic or caustic soda, or receive pre-cooked adhesives from a supplier that require no or minimal additional processing prior to use. These adhesives are designed to be usable for multiple days without a significant increase in viscosity, thereby reducing handling issues such as with pumping or feeding equipment. The viscosity of the adhesives may be maintained through chemical crosslinking and other processing methods, which stabilize the adhesive and help reduce retrogradation. However, such chemical modification increases the toxicity of the adhesive compositions and limits their widespread use in other industries.

[0005] SUMMARY

[0006] In an aspect, an adhesive composition is provided. The adhesive composition comprises a mixture comprising from about 0% or more to about 20% or less w / w water; from about 64% or more to about 99.5% or less w / w thermally treated starch; and from about 0.4% or more to about 20% or less w / w glyceride.

[0007] In another aspect, an adhesive composition is provided. The adhesive composition comprises a mixture comprising from about 0% or more to about 20% or less w / w water; from about 64% or more to about 99.5% or less w / w thermally treated starch; and from about 0.4% or more to about 20% or less w / w glyceride. Water is blended with the mixture, thereby forming an aqueous adhesive composition. Theviscosity of the aqueous adhesive composition at 0 hours after blending is from about 500 mPa*s or more to about 10,000 mPa*s or less, wherein the viscosity is measured at 23°C using a RV Brookfield DV2T viscometer, spindle 4, at 20 RPM.

[0008] In another aspect, a method of producing an adhesive composition is provided. The method comprises thermally treating a mixture to a temperature from about 50°C or more to about 220°C or less, the mixture comprising from about 0% or more to about 20% or less w / w water; from about 64% or more to about 99.5% or less w / w starch; and from about 0.4% or more to about 20% or less w / w glyceride. The method further comprises size-reducing the thermally treated mixture to particle form defined by a D90 particle size from about 20 microns or more to about 25,000 microns or less.

[0009] Further aspects and embodiments are provided in the foregoing drawings, detailed description, and claims.

[0010] DETAILED DESCRIPTION

[0011] The following description recites various aspects and embodiments of the inventions disclosed herein. No particular embodiment is intended to define the scope of the invention. Rather, the embodiments provide non-limiting examples of various compositions, and methods that are included within the scope of the claimed inventions. The description is to be read from the perspective of one of ordinary skill in the art. Therefore, information that is well known to the ordinarily skilled artisan is not necessarily included.

[0012] Definitions

[0013] The following terms and phrases have the meanings indicated below, unless otherwise provided herein. This disclosure may employ other terms and phrases not expressly defined herein. Such other terms and phrases shall have the meanings that they would possess within the context of this disclosure to those of ordinary’ skill in the art. In some instances, a term or phrase may be defined in the singular or plural. In such instances, it is understood that any term in the singular may include its plural counterpart and vice versa, unless expressly indicated to the contrary.

[0014] As used herein, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. For example, reference to “a substituent” encompasses a single substituent as well as two or more substituents, and the like.As used herein, “for example,’' “for instance,” “such as,” or “including” are meant to introduce examples that further clarify more general subject matter. Unless otherwise expressly indicated, such examples are provided only as an aid for understanding embodiments illustrated in the present disclosure and are not meant to be limiting in any fashion. Nor do these phrases indicate any kind of preference for the disclosed embodiment.

[0015] Starch is a complex carbohydrate; a polysaccharide comprising many glucose monomers. Starch is insoluble in cold water, and insoluble in alcohol. There are many potential sources of starch. The starch, for example, may be from any of com, potato, tapioca, wheat, rice, oat, barley, sorghum, millet, cassava, peas, lentils, squash, or arrowroot.

[0016] As used herein, “thermal treating” and variations thereof in reference to starch and starch-based mixtures and / or blends refers to heating that partially or fully gelatinizes starch. Thus, “thermally treated” starch is that which has been partially or fully gelatinized, as determined by the starch’s crystalline structure or loss thereof as demonstrated by amylose leaching, granule shape and the swelling thereof, the presence of maltese crosses, increased viscosity in water, and increased viscosity at progressively increasing temperatures. These characteristics may be determined using a polarized light microscope, a rapid visco analyzer, and the like.

[0017] Glycerides are esters formed from glycerol and fatty acids. As used herein glycerides include glycerol. Monoglycerides are one fatty acid attached to glycerol. Diglycerides include two fatty acids attached to glycerol. Triglycerides include three fatty acids attached to glycerol. Glycerides, especially mono- and di- glycerides, act as emulsifiers and help blend components that would normally separate, improving the stability of compositions. Glycerides may also be used to assist in solubilizing difficult to dissolve components. As used herein, “glyceride” may refer to monoglycerides, diglycerides, triglycerides, or glycerol.

[0018] The present application relates generally to starch-based adhesive compositions and methods of preparation thereof. The starch-based adhesives described herein are made from ingredients that are suitable for food applications, such as native (i. e. , uncooked or unmodified) and / or modified (i.e. , acid-thinned) starches, glycerides, and water. The adhesive composition may be formed by mixing the starch and glycerides in the presence of water at raised temperatures under shear.This process facilitates at least partial gelatinization of the starch and is controlled to meet a specific viscosity. This gelatinized starch mixture (i.e.. a “thermally treated adhesive mixture’’) does not require additional cooking or processing to be used as an adhesive. It is also believed that the process of forming the adhesive composition reduces the average molecular weight of the final starch product, thereby supporting its ability to maintain a desired viscosity and be subsequently emulsified by the glycerides to create a visco-stable product.

[0019] The glycerides described herein, when mixed with the starch in the presence of water at raised temperatures and subjected to shear forces, aid in the reduction of final viscosity of the prepared adhesive in addition to acting as a stabilizing agent. For example, it has been found that glycerides reduce the gelatinization temperature of the starch, such that adhesive compositions including glycerides have a reduced viscosity in comparison to similar compositions without glycerides. The glyceride content may be selected to reduce the viscosity of the final product to a range that enables the adhesive to be used in processing lines for manufacturing boxes, packages, and the like. In addition, it has been found that the glycerides inhibit retrogradation of the starch, thereby stabilizing the viscosity of the composition over extended periods of time.

[0020] Glycerides, including glycerol monostearate in particular, are common food ingredients used in various baking applications and consumer products. The glycerides in the adhesive compositions described herein provide comparable functionalities (e.g., viscosity and stability) as industrial ether crosslinking agents. Specifically, it has been found that these functionalities are achievable through a combination of thermal treatment (e.g., extrusion) with subsequent emulsification. In addition, the food-contact safe nature of the glycerides and other components of the adhesive composition provides a sustainable and environmentally -friendly alternative to adhesive compositions currently on the market. Accordingly, application of the adhesive compositions described herein may be expanded to industries unsuitable for chemically-crosslinked adhesives.

[0021] For example, adhesives are widely used in food-contact applications. Foodcontact applications include applications having direct or indirect contact with food. Food-contact adhesives are sometimes used to produce consumer products that have an inedible material secured to an edible material, such as ice cream cones having apaper wrapper secured to an edible cone. In such applications, the adhesive used to secure the inedible material to the edible material is in close proximity to, or potentially in direct contact with, the edible portion of the product. Thus, the adhesive compositions described herein provide an adhesive that is safe to use in such foodcontact applications.

[0022] As described above, the adhesive compositions described herein provide a visco-stable glue capable of maintaining a desired viscosity for extended periods of time. With high throughput adhesive application machines in particular, the flowable viscosity provided by the adhesive described herein enables the adhesive to be used over multiple days and / or stored in the machines during stoppages. For example, the glue fed to adhesive application machines is typically prepared in batches, wherein each batch has a limited service life. Once prepared, the adhesive compositions described herein have been found to have favorable stability and flowable viscosity, thereby providing enhanced manufacturing flexibility and increased operability of up to multiple days. Thus, the adhesive compositions described herein provide adhesive application machines with enhanced operational flexibility- and reduced downtime related to maintenance caused by adhesive-related clogging, for example.

[0023] The adhesive mixtures and compositions described herein are formed from a mixture of starch, glyceride, and water that has been thermally treated and exposed to shear forces such that the starch is at least partially gelatinized. For example, the adhesive composition may be formed by dry blending the starch and glycerides to form a homogeneous mixture. This dry- blend may then be mixed with water at raised temperatures and subjected to shear forces sufficient to at least partially gelatinize the starch. This thermally treated mixture may then be extruded, cooled, dried, and size-reduced to a specified particle size to create a starch-based adhesive composition mixture capable of being stored, shipped, and subsequently rehydrated by end-users of the adhesive at or near the time of intended application. The rehydration includes blending the thermally treated mixture with additional quantities of water and, optionally, additives such as biocide and anti-caking agents.

[0024] In any of the embodiments described herein, the dry blended mixture may comprise from about 50% or more to about 99.5% or less, from about 60% or more to about 99.5% or less, from about 70% or more to about 99.5% or less, or from about 80% or more to about 99.5% or less w / w, or is about 50, 55, 60. 62. 64. 66, 68, 70, 72,74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 97, 97, 97.5, 98, 98.5, 99, or 99.5% w / w starch.

[0025] In any of the embodiments described herein, the dry blended mixture may comprise from about 0.2% or more to about 30% or less, from about 0.3% or more to about 25% or less, from about 0.4% or more to about 20% or less, or from about 0.5 % or more to about 20% or less w / w, or is about 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9. 10, 12, 14, 16, 18, 20, 25, or 30 % w / w glyceride.

[0026] In specific embodiments alone or in combination with any other embodiment comprising monoglyceride, the glyceride may comprise from about 20% or more to about 99.9% or less, from about 20% or more to about 95% or less, from about 20% or more to about 90% or less, from about 20% or more to about 80% or less, from about 20% or more to about 70% or less, from about 20% or more to about 60% or less, from about 20% or more to about 50% or less, or from about 20% or more to about 40% or less monoglyceride by weight.

[0027] The dry blended mixture may be mixed with water at raised temperatures and subjected to shear forces so as to thermally treat and gelatinize the starch contain therein. The thermally treated mixture may then be cooled, dried, and size-reduced to create the starch-based adhesive composition.

[0028] In any of the embodiments described herein, after thermal treatment, the mixture may comprise from about 50% or more to about 99.5% or less, from about 60% or more to about 99.5% or less, from about 70% or more to about 99.5% or less, from about 75% or more to about 99.5% or less, from about 80% or more to about 99.5% or less, from about 85% or more to about 99.5% or less, from about 90% or more to about 99.5% or less, from about 95% or more to about 99.5% or less w / w, or is about 50. 55, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86. 88, 90, 92, 94, 96, 97, 97, 97.5, 98, 98.5, 99, or 99.5% w / w thermally treated starch.

[0029] In any of the embodiments described herein, after thermal treatment, the thermally treated mixture may comprise from about 0.2% or more to about 30% or less, from about 0.3% or more to about 25% or less, from about 0.4% or more to about 20% or less, or from about 0.5 % or more to about 20% or less w / w, about 5% or less, about 4% or less, about 3% or less, about 2% or less, or about 1% or less w / w,or is about 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 25, or 30 % w / w glyceride.

[0030] In any of the embodiments described herein, after thermal treatment, the thermally treated mixture may comprise from about 0% or more to about 40% or less, from about 0% or more to about 30% or less, from about 0% or more to about 20% or less, from about 0% or more to about 18% or less, from about 2% or more to about 16% or less, from about 10% or more to about 16% or less, from about 12% or more to about 14% or less w / w, about 12% or less, about 10% or less, about 8% or less, about 6% or less, or about 4% or less w / w, or is about 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 19.5, 20, 25, 30, 35, or 40 % w / w water.

[0031] In any of the embodiments described herein, the dry blended mixture is mixed with water and thermally treated to form the thermally treated mixture. Formation of the thermally treated mixture may take place in a mixing device such as, but not limited to, extruders, mixers and blenders with or without integrated heating elements, compounders, and the like. Example extruders include, but are not limited to, single screw extruders, twin screw extruders, ram extruders, co-rotating extruders, and counter-rotating extruders. In any of the embodiments described herein, the composition is mixed and heated simultaneously, wherein the heating is provided by an external source or is generated as a result of the mixing performed by the machine. Example external heating sources include, but are not limited to, electric heating devices, propane heating devices, and the like.

[0032] In any of the embodiments described herein, the mixture of starch, glyceride, and water is thermally treated at raised temperatures. In any of the embodiments described herein, the mixture may be heated to a temperature of from about 60°C or more to about 200°C or less, from about 70°C or more to about 190°C or less, from about 60°C or more to about 180°C or less, from about 80°C or more to about 180°C or less, from about 100°C or more to about 180°C or less, from about 125°C or more to about 175°C or less, or from about 140°C or more to about 160°C or less, or to a temperature of about 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100, 105, 110. 115, 120.

[0033] 125, 130, 135, 140, 145, 150, 155, 160, 165, 170, 175, 180, 185, 190, 195, 200, 205, 210, 215, or 220°C.

[0034] In any of the embodiments described herein, the thermally treated mixture may be dried at a temperature from about 20°C or more to about 100°C or less, fromabout 20°C or more to about 80°C or less, from about 30°C or more to about 60°C or less, or from about 30°C or more to about 50°C or less, or at temperatures of about 20, 25, 30, 40 ,45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, or 100°C. This drying reduces the moisture content of the thermally treated mixture to a desired level. Drying of the thermally treated mixture may be by any suitable method such as, but not limited to, drum drying, tray drying, spry drying, fluid bed drying, freeze drying, vacuum drying, centrifugation, and combinations thereof.

[0035] In any of the embodiments described herein, the thermally treated mixture after drying may comprise from about 50% or more to about 99.5% or less, from about 60% or more to about 99.5% or less, from about 70% or more to about 99.5% or less, from about 75% or more to about 99.5% or less, from about 80% or more to about 99.5% or less, from about 85% or more to about 99.5% or less, from about 90% or more to about 99.5% or less, from about 95% or more to about 99.5% or less w / w, or is about 50, 55, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82, 84, 86, 88, 90, 92, 94, 96, 97, 97, 97.5, 98, 98.5, 99, or 99.5% w / w thermally treated starch.

[0036] In any of the embodiments described herein, the thermally treated mixture after div ing may comprise from about 0.2% or more to about 30% or less, from about 0.3% or more to about 25% or less, from about 0.4% or more to about 20% or less, or from about 0.5 % or more to about 20% or less w / w, about 5% or less, about 4% or less, about 3% or less, about 2% or less, or about 1% or less w / w, or is about 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 25, or 30 % w / w glyceride.

[0037] In any of the embodiments described herein, the thermally treated mixture after drying may comprise from about 0% or more to about 40% or less, from about 0% or more to about 30% or less, from about 0% or more to about 20% or less, from about 0% or more to about 18% or less, from about 2% or more to about 16% or less, from about 10% or more to about 16% or less, from about 12% or more to about 14% or less w / w, about 12% or less, about 10% or less, about 8% or less, about 6% or less, or about 4% or less w / w. or is about 0. 1, 2, 3. 4, 5, 6, 7. 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 19.5, 20, 25, 30, 35, or 40 % w / w water.

[0038] As described above, the thermally treated mixture may be size-reduced into particle form in preparation for storage and / or shipment, for example. The thermally treated mixture may be size-reduced via any suitable mechanical means, such asmilling, grinding, crushing, and the like. The desired particle size is selected to enhance the repeated usability and storability of the dried adhesive composition. For example, smaller and finer particles are lighter and disperse more easily in the air. These smaller and finer particles may lead to dusting or clouding. Such particles are typically 100 microns or less, with particles of 75 microns or less generally dispersing farther and remaining suspended for longer periods of time. Larger particles, for example particles larger than 1,000 microns, on the other hand are more difficult to mix and dissolve into solution. The desired particle size described herein is selected to minimize dust clouding while still enabling the thermally treated mixture to be blended with water homogeneously.

[0039] In any of the embodiments described herein, the size-reduced thermally treated mixture may have a D90 particle size from about 20 microns or more to about 25,000 microns or less, from about 100 microns or more to about 10,000 microns or less, from about 250 microns or more to about 5,000 microns or less, or from about 300 microns or more to about 1,000 microns or less, or the D90 particle size is about 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 1,000, 1,500, 2,000, 2,500, 3,000, 3.500, 4,000, 4,500, 5,000. 5,500, 6,000. 6,500, 7.000, 7,500, 8.000, 8,500, 9.000, 9.500, 10,000, 11,000, 12,000, 13,000, 14,000, 15,000, 16,000, 17,000, 18,000, 19,000, 20,000, 21,000, 22,000, 23,000, 23,500, 24,000, 24,500, or 25,000 microns.

[0040] As used herein, the term “D## particle size” means that ##% of the particles of the mixture have a maximum dimension that is less than or equal to the noted value (e.g., 10 microns), based on a volume basis. For example, D10, D50, and D90 values refer to the particle size in which 10%. 50%. and 90% of the sampled particles are smaller than, respectively. Particle size distribution of the ground extrudate (i.e., the size-reduced thermally treated mixture) was measured in its dry state using laser diffraction (Malvern Mastersizer 3000, Aero S accessory ), and is reported as volume density (%). Air pressure was 1 bar, 75% feed, and the obscuration limits were set between 0% to 15%. A refractive index of 1.52, particle density of 1.05 g / cm3, and absorption index of 0.10 were chosen as the material properties. A homogenous sample was loaded into the sample holder and the height and vibration were adjusted until a steady flow of the sample was achieved and fed into the Malvern Mastersizer. The hopper gap was adjusted as necessary between 0.50 and 3 mm to achieve the steady flow.The thermally treated mixture may be blended with water to rehydrate the dried composition, thereby forming an aqueous adhesive composition. In any of the embodiments described herein, the ratio of the water to the thermally treated mixture in the aqueous adhesive composition may be from about 3: 1 or more to about 12: 1 or less, from about 3 : 1 or more to about 12:1 or less, from about 4: 1 or more to about 8:1 or less, or from about 4:1 or more to about 6:1 or less, or at a ratio of about 3:1. 4:1, 5:1. 6:1, 7:1 8:1, 9:1. 10:1. 11:1. or 12:1 w / w.

[0041] It has been found that the aqueous adhesive composition described herein provides a visco-stable glue capable of maintaining a desired viscosity for extended periods of time. In any of the embodiments described herein, the viscosity of the aqueous adhesive composition, wherein the viscosity is measured using a RV Brookfield DV2T viscometer, spindle 4, at 20 RPM, at 0 hours (initial viscosity) or more to 72 hours or less from blending the thermally treated mixture with water may be from about 500 mPa*s or more to about 10,000 mPa*s or less, from about 1,000 mPa*s or more to about 5,000 mPa*s or less, from about 1,500 mPa*s or more to about 3,500 mPa*s or less, from about 2,000 mPa*s or more to about 4,000 mPa*s or less, or from about 2.500 mPa*s or more to about 3.000 mPa*s or less, or is about 500, 600, 800, 1,000, 1,200, 1,400, 1,600, 1,800, 2,000, 2,200, 2,600, 2,800, 3,000, 3,200, 3,400, 3,600, 3,800, 4,000, 4,500, 5,000, 5,500, 6,000, 6,500, 7,000, 7,500, 8,000, 8,500, 9,000, 9,500, or 10,000 mPa*s.

[0042] In any of the embodiments described herein, the initial viscosity of the aqueous adhesive composition, wherein the viscosity' is measured using a RV Brookfield DV2T viscometer, spindle 4. at 20 RPM, at 0 hours from blending may be from about 500 mPa*s or more to about 10,000 mPa*s or less, from about 600 mPa*s or more to about 5,000 mPa*s or less, from about 700 mPa*s or more to about 2,500 mPa*s or less, from about 800 mPa*s or more to about 2,000 mPa*s or less, or from about 900 mPa*s or more to about 1,500 mPa*s or less, or is about 500, 600, 700, 800, 900, 1,000, 1,100, 1,200, 1,300, 1,400, 1,500, 2,000, 2,200, 2,600, 2,800, 3,000, 3,200, 3,400, 3,600, 3,800, 4,000, 4,500, 5,000, 5,500, 6,000, 6,500, 7,000, 7,500, 8,000, 8,500, 9,000, 9,500, or 10,000 mPa*s.

[0043] In any of the embodiments described herein, the viscosity of the aqueous adhesive composition, wherein the viscosity is measured using a RV Brookfield DV2T viscometer, spindle 4. at 20 RPM, at 24 hours from blending may be fromabout 500 mPa*s or more to about 10,000 mPa*s or less, from about 800 mPa*s or more to about 5,000 mPa*s or less, from about 1,000 mPa*s or more to about 2,500 mPa*s or less, from about 1,200 mPa*s or more to about 2,000 mPa*s or less, or from about 1,400 mPa*s or more to about 1,800 mPa*s or less, or is about 500, 750, 1,000, 1,100, 1,200, 1,300, 1,400, 1,500, 1,600, 1,700, 1,800, 1,900, 2,000, 2,200, 2,600, 2.800, 3,000, 3,200, 3,400, 3,600, 3,800. 4,000, 4,500, 5,000, 5.500, 6,000, 6.500, 7.000, 7,500. 8,000, 8,500. 9,000, 9.500. or 10,000 mPa*s.

[0044] In any of the embodiments described herein, the viscosity of the aqueous adhesive composition, wherein the viscosity is measured using a RV Brookfield DV2T viscometer, spindle 4, at 20 RPM, at 48 hours from blending may be from about 500 mPa*s or more to about 10,000 mPa*s or less, from about 800 mPa*s or more to about 5,000 mPa*s or less, from about 1,000 mPa*s or more to about 3,000 mPa*s or less, from about 1,200 mPa*s or more to about 2,500 mPa*s or less, or from about 1,600 mPa*s or more to about 2,000 mPa*s or less, or is about 500, 750, 1,000, 1,100, 1,200, 1,300, 1,400, 1,500, 1,600, 1,700, 1,800, 1,900, 2,000, 2,200, 2,600, 2.800, 3,000, 3,200, 3,400, 3,600, 3,800. 4,000, 4,500, 5,000, 5,500, 6,000, 6.500, 7.000, 7,500, 8,000, 8,500. 9,000, 9,500. or 10,000 mPa*s.

[0045] In any of the embodiments described herein, the viscosity of the aqueous adhesive composition, wherein the viscosity is measured using a RV Brookfield DV2T viscometer, spindle 4, at 20 RPM, at 72 hours from blending may be from about 500 mPa*s or more to about 10,000 mPa*s or less, from about 1,000 mPa*s or more to about 5,000 mPa*s or less, from about 1,500 mPa*s or more to about 3,000 mPa*s or less, from about 1,750 mPa*s or more to about 2,500 mPa*s or less, or from about 2,000 mPa*s or more to about 2,500 mPa*s or less, or is about 500, 750, 1,000, 1,250, 1,500, 1,750, 1,800, 1,900, 2,000, 2,100, 2,200, 2,300, 2,400, 2,500, 2,600, 2.800, 3,000, 3,200, 3,400, 3,600, 3,800, 4,000, 4,500, 5,000, 5,500, 6,000, 6.500, 7.000, 7,500, 8,000, 8,500. 9,000, 9,500. or 10,000 mPa*s.

[0046] In any of the embodiments described herein, the viscosity of the aqueous adhesive composition remains within from about 0% or more to about 40% or less, from about 0% or more to about 30% or less, from about 0% or more to about 20% or less, or from about 0% or more to about 10% or less of the initial viscosity at from 24 hours or more to 72 hours or less, wherein the aqueous adhesive composition is at a temperature of from about 20°C or more to about 30°C or less. In any of theembodiments described herein, the viscosity of the aqueous adhesive composition remains within from about 0% or more to about 50% or less, from about 0% or more to about 40% or less, from about 0% or more to about 30% or less, from about 0% or more to about 20% or less, or from about 0% or more to about 10% or less of the initial viscosity at from 24 hours or more to 96 hours or less from the time of mixing, wherein the aqueous adhesive composition is at a temperature of from about 20°C or more to about 30°C or less. In any of the embodiments descnbed herein, the viscosity of the aqueous adhesive composition remains within from about 0% or more to about 60% or less of the initial viscosity for about 24, 36, 48, 60, 72, 96, or 120 hours, wherein the aqueous adhesive composition is at a temperature of from about 20°C or more to about 30°C or less.

[0047] Without being bound by any particular theory, it is believed thermally treating the starch in the presence of glyceride alters the starch molecules, such as by reducing the molecular weight of the starch in the composition. In any of the embodiments described herein, the molecular weight of the starch after thermal treating in the presence of glyceride may be decreased by from about 5% or more to about 70% or less, from about 10% or more to about 60% or less, or from about 15% or more to about 50% or less, or by about 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, or 70%. This reduction in molecular weight is believed to support the ability of the starch to have a specified desired viscosity and then be subsequently emulsified by glycerides to create a visco-stable product.

[0048] In any of the embodiments described herein, additives such as biocide and anti-caking agents are optionally added. Anti-caking agents may be used as a processing aid in dry mixing. Biocides may be used as a processing aid at rehydration when forming the aqueous adhesive composition to extend the shelf life of the adhesive. The biocide may assist in maintaining viscosity by preventing microbial growth. The biocide and anti-caking agents may be food-contact safe to enable the aqueous adhesive composition to be used in a wide range of industrial applications. Example food-contact safe biocide agents consist of or include, but are not limited to including, hydrogen peroxide, lactic acid, citric acid, essential oils, peracetic acid, acetic acid, chitosan, and mixtures thereof. Example food-contact safe anti-caking agents consist of or include, but are not limited to including, silicon dioxide, calciumsilicate, magnesium stearate, tricalcium phosphate, rice hull powder, calcium carbonate, magnesium carbonate, and potassium ferrocyanide, and mixtures thereof.

[0049] EXAMPLES

[0050] Example 1

[0051] Flaked glycerol monostearate (Spectrum Chemical), which had a profile of 30% monoglyceride, 36% diglyceride, 10% triglyceride, and 5% glycerol by weight, was ground to a powder and dry mixed until homogeneous with native dent com starch (90% starch dwb, ADM) at 2% (w / w) dry starch. The mixed material was fed into a Leistritz® Twin Screw Extruder (27 mm) with a high shear extruder configuration, including conveying, kneading, and reverse flow elements. The dry material was fed into the extruder at a rate of 50 Ib / hr, with water fed at a rate of 2.8 L / hr. The mixture was blended, with screws rotating at 550 RPM, and heated until its temperature reached 160°C. Extrudates were collected from the 5 mm die exit, dried to a moisture content of less than 14% by weight at 40°C, and milled to 100 microns.

[0052] 1 part extruded starch to 5 parts tap water w / w was blended for 45 minutes at 1500 RPM with an overhead mixer to prepare the adhesive. Viscosity at 23°C was determined over a 72-hour period at 24-hour intervals using a RV Brookfield DV2T viscometer, spindle 4, at 20 RPM. The results are shown in Table 1 below.

[0053] Table 1

[0054]

[0055] The adhesive was found to maintain a viscosity of under 3,000 mPa*s for a minimum of 72 hours.

[0056] Example 2

[0057] Powdered glycerol monostearate (GMS, Brentagg®), which has a minimum monoglyceride concentration of 90% by weight, was dry mixed with either nativecom or wheat starch (ADM) at a loading value of 2% (w / w) dry starch basis. The mixed material was fed into a Twin-Screw Extruder (GEA, 58 mm) at a rate of 200 kg / hr with a high shear configuration. Additionally, water was fed at a rate of 5 L / hr with screws rotating at a rate of 400 RPM. The product reached a minimum temperature of 150°C before exiting the extruder. Extrudate was cooled to room temperature and ground utilizing a Retsch® mill with a 2 mm sieve. The adhesive was prepared by blending 30 g of starch with 150 g of tap water in an overhead mixer for 60 minutes at 650 RPM. After blending, the adhesive was acclimated to 23°C and viscosity was measured immediately (Vo), and after 24 hours. At 24 hours, viscosity was measured with and without temperature adjustment, V24hr, initial and V24hr, 23°c respectively. Viscosity was measured viaRV Brookfield DV2T viscometer, spindle 4, at 20 RPM. The results are shown in Table 2 below.

[0058] Table 2

[0059]

[0060] It was found that the adhesives produced in this example were glossy white, did not have precipitates present, and remained free flowing after 24 hours.

[0061] Example 3

[0062] Wheat starch extrudate, and the corresponding adhesive, was prepared using the process of Example 2. Viscosity was measured utilizing an RV Brookfield DV2T viscometer at 20 RPM with RV 4 spindle. Viscosity measurements were taken without temperature adjustment immediately after preparation, at 24 hours and at 72 hours post-blending. The results are shown in Table 3 below.

[0063] Table 3

[0064]

[0065] This example demonstrated the wheat starch adhesive maintains a stable viscosity over extended periods of time, up to at least 72 hours. These results contrast with and may be compared to the results of Example 4.

[0066] Example 4

[0067] Com starch without GMS was fed into a Twin-Screw Extruder (GEA, 58 mm) at a rate of 150 kg / hr with a high shear configuration. Additionally, water was fed at a rate of 3.8 L / hr with screws rotating at a rate of 400 RPM. The product reached a minimum temperature of 150°C before exiting the extruder. The extrudate was cooled to room temperature and ground utilizing a Retsch® mill with a 2 mm sieve. The adhesive was prepared by mixing 30 g of starch with 150 g of tap water, and blending with an overhead mixer for 60 minutes at 650 RPM. After blending, the adhesive was acclimated to 23°C and viscosity was measured immediately (Vo), and after 24 hours. At 24 hours, viscosity' was measured with and without temperature adjustment, V24hr, initial and V24hr, 23°c respectively. Viscosity was measured via RV Brookfield DV2T viscometer, with spindle number and shear rate adjusted accordingly. The results are shown in Table 4 below.

[0068] Table 4

[0069]

[0070] This example demonstrated the impact of GMS in starch-based adhesives. Specifically, it was found that the viscosity of the adhesive increased dramatically over extended periods of time. Thus, the desired viscosity, viscosity' stability, and flowability of the adhesive was not maintained for the desired application.

[0071] Different RV spindles were used to measure the viscosity of the various samples. In general, RV Spindle 4 is capable of measuring viscosity up to about 10,000 mPa*s. However, the viscosity of the GMS-free blends greatly exceeded * , Unadjusted Temperature and the 24hr,

[0072]

[0073] Temperature Adjusted to 23 °C examples were adjusted accordingly to enable the respective viscosity’ measurements to be obtained.

[0074] Example 5

[0075] Extrudates from wheat and com were produced using the process of Example 2. The adhesive was prepared by blending 30 g of starch with 150 g of tap water, mixing with an overhead mixer for 45 minutes at 1500 RPM. After blending, the adhesive was acclimated to 23°C and viscosity' was measured immediately (Vo), and after 24 hours. At 24 hours, viscosity' was measured with and without temperature adjustment. V24hr, initial and V24hr, 23°c respectively. The results are shown in Table 5 below.

[0076] Table 5

[0077]

[0078] In this example, when compared to Example 2, it was demonstrated that the adhesives can be prepared at different RPMs and mixing times with little to no impact on the visco-stability' of the adhesive.

[0079] Example 6

[0080] In this example, different extrudates were evaluated to determine the impact of glyceride modification on molecular weight. Com and Wheat starch adhesive extmdates were prepared using the process of Example 2. Com starch extrudate without GMS was prepared according to Example 4. Native com starch was analyzed as a control.

[0081] Samples were analyzed using a Tosoh EcoSEC GPC (gel permeation chromatography) outfitted with a Wyatt system including three detectors (light scattering, viscometer, and refractive index) and a Tosoh TSKgel a-M column.

[0082] Dimethyl Sulfoxide with 0.5% Lithium Bromide was used as the solvent at a flow rate of 0.6 mL / min at room temperature. The samples were prepared at a concentration of5.0 mg / mL in DMSO + 0.5% LiBr. Absolute molecular weight was calculated based on results from the detectors via the Wyatt Astra software.

[0083] Table 6

[0084]

[0085] This example demonstrated the presence of glycerides in extrudates reduces the molecular weight of the various starches when compared to the native com starch control.

[0086] Example 7

[0087] Powdered glycerol monostearate (GMS, Brentagg®), which has a minimum monoglyceride concentration of 90% by weight, was dry' mixed with either native com (ADM) at a loading value of 2% (w / w) dry starch basis. The mixed material was fed into a Twin Screw Extruder (GEA. 58 mm) at a rate of 300 kg / hr with a high shear configuration. Additionally, water was fed at a rate of 7.6 L / hr and screws were rotated at a rate of 400 RPM. The product reached a minimum temperature of 150°C before exiting the extruder. Extrudate was cooled to room temperature and ground utilizing a Retsch® mill with a 2 mm sieve. The adhesive was prepared by blending 25 g of starch with 125 g of tap water, blending with an overhead mixer for 45 minutes at 1500 RPM. After blending, the adhesive was acclimated to 23°C and viscosity was measured immediately (Vo), and after 24 hours. At 24 hours, viscosity7was measured without temperature adjustment, (V24hr). Viscosity was measured via RV Brookfield DV2T viscometer, spindle RV 4 at 20 RPM. The results are shown in Table 7 below.

[0088] Table 7

[0089]

[0090] The invention has been described with reference to various specific and preferred embodiments and techniques. Nevertheless, it is understood that manyvariations and modifications may be made while remaining within the spirit and scope of the invention.

[0091]

Claims

WHAT IS CLAIMED IS:

1. An adhesive composition comprising:a mixture comprising:from about 0% or more to about 20% or less w / w water; from about 64% or more to about 99.5% or less w / w thermally treated starch; andfrom about 0.4% or more to about 20% or less w / w glyceride.

2. An adhesive composition comprising;a blend of water and the mixture of claim 1 , thereby forming an aqueous adhesive composition,wherein the ratio of the water to the mixture of claim 1 in the aqueous adhesive composition is from about 3: 1 or more to about 12: 1 or less, from about 3: 1 or more to about 12: 1 or less, from about 4: 1 or more to about 8: 1 or less, or from about 4: 1 or more to about 6: 1 or less w / w.

3. The adhesive composition of claim 2, wherein the aqueous adhesive composition has a viscosity' at 0 hours or more to 72 hours or less from blending of from about 500 mPa*s or more to about 10,000 mPa*s or less, from about 1,000 mPa*s or more to about 5,000 mPa*s or less, from about 1,500 mPa*s or more to about 3,500 mPa*s or less, from about 2,000 mPa*s or more to about 4,000 mPa*s or less, or from about 2,500 mPa*s or more to about 3,000 mPa*s or less, wherein the viscosity is measured at 23°C using a RV Brookfield DV2T viscometer, spindle 4, at 20 RPM.

4. An adhesive composition comprising:a mixture comprising:from about 0% or more to about 20% or less w / w water; from about 64% or more to about 99.5% or less w / w thennally treated starch; andfrom about 0.4% or more to about 20% or less w / w glyceride; andwater blended with the mixture, thereby forming an aqueous adhesive composition,wherein the viscosity of the aqueous adhesive composition at 0 hours after blending is from about 500 mPa*s or more to about 10,000 mPa*s or less, wherein the viscosity7is measured at 23°C using a RV Brookfield DV2T viscometer, spindle 4. at 20 RPM.

5. The adhesive composition of claim 4, wherein the viscosity of the aqueous adhesive composition at 24 hours after blending is from about 500 mPa*s or more to about 10,000 mPa*s or less, from about 800 mPa*s or more to about 5,000 mPa*s or less, from about 1,000 mPa*s or more to about 2,500 mPa*s or less, from about 1,200 mPa*s or more to about 2,000 mPa*s or less, or from about 1,400 mPa*s or more to about 1,800 mPa*s or less, wherein the viscosity7is measured at 23°C using a RV Brookfield DV2T viscometer, spindle 4. at 20 RPM.

6. The adhesive composition of any of claims 4-5, wherein the viscosity of the aqueous adhesive composition at 48 hours after blending is from about 500 mPa*s or more to about 10,000 mPa*s or less, from about 800 mPa*s or more to about 5,000 mPa*s or less, from about 1,000 mPa*s or more to about 3,000 mPa*s or less, from about 1,200 mPa*s or more to about 2,500 mPa*s or less, or from about 1,600 mPa*s or more to about 2.000 mPa*s or less, wherein the viscosity is measured at 23°C using a RV Brookfield DV2T viscometer, spindle 4, at 20 RPM.

7. The adhesive composition of any of claims 4-6, wherein the viscosity of the aqueous adhesive composition at 72 hours after blending is from about 500 mPa*s or more to about 10,000 mPa*s or less, from about 1,000 mPa*s or more to about 5,000 mPa*s or less, from about 1,500 mPa*s or more to about 3,000 mPa*s or less, from about 1,750 mPa*s or more to about 2,500 mPa*s or less, or from about 2,000 mPa*s or more to about 2,500 mPa*s or less, wherein the viscosity is measured at 23°C using a RV Brookfield DV2T viscometer, spindle 4, at 20 RPM.

8. The adhesive composition of any of claims 4-7, wherein the aqueous adhesive composition further comprises a biocide agent.

9. The adhesive composition of claim 8, wherein the biocide agent comprises one or more of hydrogen peroxide, lactic acid, citric acid, essential oils, peracetic acid, acetic acid, and chitosan.

10. The adhesive composition of any of claims 4-9, wherein the aqueous adhesive composition further comprises an anti-caking agent.

11. The adhesive composition of any of claims 4-10, wherein the anti-caking agent comprises one or more of silicon dioxide, calcium silicate, magnesium stearate, tricalcium phosphate, rice hull powder, calcium carbonate, magnesium carbonate, and potassium ferrocyanide.

12. The adhesive composition of any of the preceding claims, wherein the water in the mixture is present from about 0% or more to about 18% or less, from about 2% or more to about 16% or less, from about 10% or more to about 16% or less, or from about 12% or more to about 14% or less w / w, or about 12% or less, about 10% or less, about 8% or less, about 6% or less, or about 4% or less w / w.

13. The adhesive composition of any of the preceding claims, wherein the thermally treated starch in the mixture is present from about 70% or more to about 99.5% or less, from about 75% or more to about 99.5% or less, from about 80% or more to about 99.5% or less, from about 85% or more to about 99.5% or less, from about 90% or more to about 99.5% or less, from about 95% or more to about 99.5% or less w / w.

14. The adhesive composition of any of the preceding claims, wherein the glyceride in the mixture is present at about 5% or less, about 4% or less, about 3% or less, about 2% or less, or about 1% or less w / w.

15. The adhesive composition of any of the preceding claims, wherein the glyceride comprises one or more of a monoglyceride, a diglyceride, a triglyceride, and glycerol.

16. The adhesive composition of any of the preceding claims, wherein the glyceride comprises from about 20% or more to about 95% or less monoglyceride by weight.

17. The adhesive composition of any of the preceding claims, wherein the glyceride is Glycerol Monostearate.

18. The adhesive composition of any of the preceding claims, wherein the mixture is in particle form, the mixture having a D90 particle size from about 20 microns or more to about 25,000 microns or less, from about 100 microns or more to about 10,000 microns or less, from about 250 microns or more to about 5,000 microns or less, or from about 300 microns or more to about 1,000 microns or less.

19. The adhesive composition of any of the preceding claims, wherein the thermally treated starch comprises one or more of com starch, wheat starch, tapioca starch, and potato starch.

20. A method of producing an adhesive composition, the method comprising: thermally treating a mixture to a temperature from about 50°C or more to about 220°C or less, the mixture comprising:from about 0% or more to about 20% or less w / w water; from about 64% or more to about 99.5% or less w / w starch; and from about 0.4% or more to about 20% or less w / w glyceride; size-reducing the thermally treated mixture to particle form defined by a D90 particle size from about 20 microns or more to about 25,000 microns or less.

21. The method of claim 20, wherein the thermally treating heats the mixture to a temperature from about 60°C or more to about 200°C or less, from about 70°C or more to about 190°C or less, from about 60°C or more to about 180°C or less, from about 80°C or more to about 180°C or less, from about 100°C or more to about 180°C or less, from about 125°C or more to about 175°C or less, or from about 140°C or more to about 160°C or less.

22. The method of any of claims 20-21, wherein the thermally treating is performed via extrusion.

23. The method of any of claims 20-22, further comprising dry ing the thermally treated mixture prior to the size-reducing, wherein the moisture content of the dried thermally treated mixture is from about 8% or more to about 18 % or less, from about 10% or more to about 16% or less, from about 12% or more to about 14% or less, or about 12% or less w / w.

24. The method of any of claims 20-23, wherein the drying is performed at a temperature from about 20°C or more to about 100°C or less, from about 20°C or more to about 80°C or less, from about 30°C or more to about 60°C or less, or from about 30°C or more to about 50°C or less.

25. The method of any of claims 20-24, further comprising blending the thermally treated mixture with water to form an aqueous adhesive composition having a viscosity at 0 hours or more to 72 hours or less of from about 500 mPa*s or more to about 10,000 mPa*s or less, from about 1,000 mPa*s or more to about 5,000 mPa*s or less, from about 1.500 mPa*s or more to about 3,500 mPa*s or less, from about 2,000 mPa*s or more to about 4,000 mPa*s or less, or from about 2,500 mPa*s or more to about 3,000 mPa*s or less, wherein the viscosity is measured at 23°C using a RV Brookfield DV2T viscometer, spindle 4, at 20 RPM.

26. The method of claim 25, wherein the ratio of the water to the thermally treated mixture in the aqueous adhesive composition is from about 3:1 or more to about 12:1 or less, from about 3 : 1 or more to about 12:1 or less, from about 4: 1 or more to about 8: 1 or less, or from about 4: 1 or more to about 6: 1 or less w / w.

27. The method of any of claims 25-26, wherein the aqueous adhesive composition further comprises a biocide agent.

28. The method of any of claims 25-27, wherein the biocide agent comprises one or more of hydrogen peroxide, lactic acid, citric acid, essential oils, peracetic acid, acetic acid, and chitosan.

29. The method of any of claims 25-28, wherein the aqueous adhesive composition further comprises an anti-caking agent.

30. The method of any of claims 25-29, wherein the anti-caking agent comprises one or more of silicon dioxide, calcium silicate, magnesium stearate, tricalcium phosphate, rice hull powder, calcium carbonate, magnesium carbonate, and potassium ferrocyanide.

31. The method of any of claims 20-30, wherein the water in the mixture is present from about 8% or more to about 18 % or less, from about 10% or more to about 16% or less, from about 12% or more to about 14% or less, or about 12% or less w / w.

32. The method of any of claims 20-31, wherein the starch in the mixture is present from about 70% or more to about 99.5% or less, from about 75% or more to about 99.5% or less, from about 80% or more to about 99.5% or less, from about 85% or more to about 99.5% or less, from about 90% or more to about 99.5% or less, from about 95% or more to about 99.5% or less w / w.

33. The method of any of claims 20-32, wherein the glyceride in the mixture is present at about 5% or less, about 4% or less, about 3% or less, about 2% or less, or about 1% or less w / w.

34. The method of any of claims 20-33, wherein the glyceride comprises one or more of a monoglyceride, a diglyceride, a triglyceride, and glycerol.

35. The method of any of claims 20-34, wherein the glyceride comprises from about 20% or more to about 95% or less monoglyceride by weight.

36. The method of any of claims 20-35, wherein the glyceride is Glycerol Monostearate.

37. The method of any of claims 20-36, wherein the thermally treated mixture is size-reduced to a D90 particle size from about 20 microns or more to about 25,000 microns or less, from about 100 microns or more to about 10,000 microns or less, from about 250 microns or more to about 5,000 microns or less, or from about 300 microns or more to about 1,000 microns or less.

38. The method of any of claims 20-37, wherein the starch comprises one or more of com starch, wheat starch, tapioca starch, and potato starch.

39. The adhesive composition or method of any of the preceding claims, wherein thermally treated or thermal treating means the partial or full gelatinization of starch, as determined by the starch’s crystalline structure or loss thereof as demonstrated by amylose leaching, granule shape and the swelling thereof, the presence of maltese crosses, increased viscosity in water, and increased viscosity at progressively increasing temperatures.

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