Method for producing biodegradable compositions of bio-derived starch esters

Abstract

A biodegradable and / or compostable composition of a bio-derived starch mixed ester contains a mixed starch mixed ester having a total degree of substitution of at least 1.0, and the ester substituents are (a) acetate and (b) one or more C 10 ~C 24 a mixed group of ester residues, and the degree of substitution of (a) is greater than that of (b). A method for producing a biodegradable and / or compostable composition of a bio-derived starch mixed ester having a degree of substitution of at least 1.0 includes reacting starch with a mixed acid anhydride in the presence of an esterification catalyst to form a starch mixed ester composition, and the mixed acid anhydride is formed from (a) an acid anhydride and (b) a carboxylic acid having 10 to 24 carbon atoms.

Description

Technical Field

[0001] This application claims the benefit of priority of U.S. Patent Application No. 63 / 393,506, filed on July 29, 2022, U.S. Patent Application No. 63 / 393,509, filed on July 29, 2022, and U.S. Patent Application No. 63 / 393,515, filed on July 29, 2022, the entire contents of each of which are incorporated herein by reference.

[0002] The present disclosure relates to biodegradable and / or compostable compositions of starch mixed esters of biological origin, wherein the starch is provided from a non-petroleum source, i.e., a plant or biological source. The present disclosure also includes a method for producing a biodegradable composition of starch mixed esters of biological origin described herein.

Background Art

[0003] The accumulation of plastic waste in the environment is increasing social concerns. Various solutions and waste disposal routes, such as recycling, composting, and energy recovery through incineration, are being explored to reduce the amount of plastic reaching the environment and landfills. One way to reduce the pollution associated with fossil-derived plastics is through the development and use of biological and biodegradable polymers.

[0004] For this purpose, polymers from biological starch have been studied; however, there are currently no commercially available biodegradable and / or compostable compositions of starch mixed esters of biological origin.

Summary of the Invention

Means for Solving the Problems

[0005] Aspects and embodiments of the present invention are set forth in the appended claims. These and other aspects and embodiments of the present invention are also described herein.

[0006] Described are biodegradable and / or compostable compositions of starch esters of biological origin, and methods for producing them. In one embodiment, the method includes reacting at least one anhydride, at least one acid, and biological origin starch in the presence of a catalyst to form a biodegradable and / or compostable composition of starch esters. In some embodiments, at least one anhydride and at least one acid can first be reacted to form a mixed acid anhydride, which can then be reacted with biological origin starch in the presence of a catalyst to form a biodegradable and / or compostable composition of starch esters. Advantageously, these reactions occur in the presence of bound and / or free water in the starch and / or catalyst.

[0007] In another embodiment, an acid is mixed with an anhydride to form an anhydride mixture. Separately, an anhydride, which may or may not be the same as that used to form the anhydride mixture, is reacted with starch in the presence of a catalyst, which is a typical base such as a hydroxide like sodium hydroxide. The product is dehydrated and reacted with the anhydride mixture while the starch is esterified to form a biodegradable and / or compostable composition of starch esters, which can be washed and dried to form the desired product.

[0008] In yet another embodiment, an acid, an acid anhydride, a catalyst, and starch can be mixed in a single reactor, where the starch is dehydrated and esterified to form a biodegradable and / or compostable composition of starch esters.

[0009] In one example, the first mixed acid anhydride and the second mixed acid anhydride are formed separately, and after formation, they are mixed together and then reacted with starch. In this regard, the first anhydride may be reacted with the first acid to form the first mixed acid anhydride, and the second anhydride may be reacted with the second acid to form the second mixed acid anhydride. The first anhydride and the second anhydride may be different, but are generally the same, and when the same, it may be acetic anhydride. Typically, the first acid and the second acid are different. Then, the first anhydride and the second anhydride are mixed, and then reacted with starch in the presence of a catalyst to form a biodegradable and / or compostable composition of starch mixed esters.

[0010] In another example, the first mixed acid anhydride, the second mixed acid anhydride, and the third mixed acid anhydride are formed separately, and after formation, they are mixed together and then reacted with starch. In this regard, the first anhydride may be reacted with the first acid to form the first mixed acid anhydride, the second anhydride may be reacted with the second acid to form the second mixed acid anhydride, and the third anhydride may be reacted with the third acid to form the third mixed acid anhydride. Each of the first, second, and third anhydrides may be different, but are generally the same, and when the same, it may be acetic anhydride. Typically, each of the first, second, and third acids is different. After the formation of the first, second, and third mixed acid anhydrides, they are mixed, and then reacted with starch in the presence of a catalyst to form a biodegradable and / or compostable composition of starch mixed esters.

[0011] In yet another embodiment, the acid anhydride is mixed with starch and mixed with a catalyst for a time sufficient to dehydrate the starch and water that may be present in relation to the catalyst under suitable conditions. In one example, the acid anhydride may be acetic anhydride, the catalyst may be a 50% aqueous NaOH solution, and the starch may be derived from corn starch, which may be high amylose corn starch. Then, C 2~24An acid that can be a carboxylic acid, and an additional amount of acid anhydride, are added to the reaction raw materials under conditions suitable for esterifying starch to form a biodegradable and / or compostable composition of starch mixed esters. Thereafter, the resulting mixture can be washed with water to remove unreacted reaction products, resulting in a washed-with-water starch mixed ester product, which may be dried. It is also contemplated that the washed-with-water starch mixed ester product can be further washed with an alcohol such as ethanol to remove unreacted acid, resulting in a washed-with-alcohol starch mixed ester product, which may be dried. Alternatively, the dehydrated product may optionally be introduced into an extruder for further processing, together with additives or other biodegradable and / or compostable polymers, as will be described in more detail below. As another alternative, it is intended that the water- and alcohol-washed product be dried and then blended with one or more biodegradable and / or compostable polymers.

[0012] In some examples, one or all of the starch, fatty acid, and anhydride are derived from a biological source, i.e., from plants rather than from a petroleum source, and for this reason, the method for producing the starch mixed ester composition described herein, and the resulting starch mixed ester composition, are intended to be free of starch, fatty acid, and anhydride from a petroleum source.

[0013] The resulting biodegradable and / or compostable composition of starch mixed esters (washed with water, washed with alcohol, or otherwise) can have any suitable physical form, such as liquid, powder, particles, resin, etc., but is not limited thereto.

[0014] The starch mixed ester compositions described herein (unwashed, washed with water, washed with alcohol, or otherwise) are intended to be blendable with one or more other biodegradable and / or compostable polymers. In this regard, the resulting blend can comprise from about 20% to about 90% of the starch mixed ester described herein, and from about 10% to about 80% of at least one other biodegradable and / or compostable polymer. The blend can be prepared by melt processing using an extruder.

[0015] In some embodiments, articles are intended to be made from the compositions described herein (both the starch mixed ester compositions and blends). To that end, the compositions can be processed by a variety of methods known in the art such as, but not limited to, extrusion, injection molding, compression molding, film forming, blow molding, vacuum forming, thermoforming, extrusion molding, coextrusion, foaming, profile extrusion, combinations thereof, as well as other known and intended methods. For example, the compositions can be injection molded to produce a variety of molded articles that can be biodegradable and / or compostable.

[0016] As used herein, the term “biodegradable” refers to a plastic or polymeric material that undergoes at least partial biodegradation by organisms (microorganisms) in an anaerobic and aerobic environment (determined by ASTM D5511), a soil environment (determined by ASTM D5988), a freshwater environment (determined by ASTM D5271 (EN 29408)), or a marine environment (determined by ASTM D6691 or ISO14852). The biodegradability of biodegradable plastics can also be determined using ASTM D6868, ASTM D6400, and European EN13432.

[0017] As used herein, the term "compostable" refers to biodegradable materials that may decompose into only carbon dioxide, water, inorganic compounds, and / or biomass and leave no visible or toxic residues. In some embodiments, articles formed from the compositions described herein may be biodegradable or "compostable" as determined by ASTM D6400 and / or ASTM D6868 with respect to industrial and / or home compostability.

[0018] The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings, and from the claims.

[0019] All percentages used or recited in the description herein refer to mass percentages unless otherwise specified. Other aspects and advantages of the invention will be understood from the following detailed description of the invention.

[0020] The present invention extends to methods, systems, and apparatuses as substantially described herein and / or illustrated with reference to the accompanying drawings.

[0021] The present invention extends to any novel aspect or feature described and / or illustrated herein. Additionally, aspects of the apparatus may be applied to aspects of the method and vice versa. Further, any, some, and / or all features in one aspect may be applied to any, some, and / or all features in any other aspect in any suitable combination.

[0022] It should also be understood that particular combinations of the various features described and defined in any aspect of the present invention may be implemented, supplied, and / or used independently. BRIEF DESCRIPTION OF THE DRAWINGS

[0023]

Figure 1

Figure 2

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Figure 4

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Figure 6A

Figure 6B

Figure 6C

Figure 7A

Figure 7B

Figure 7C

Figure 8A

Figure 8B

Figure 8C

Figure 9

DETAILED DESCRIPTION OF THE INVENTION

[0024] Referring to FIG. 1, there is shown a proposed flow diagram of a process for making biodegradable and / or compostable compositions of starch mixed esters derived from living organisms as described herein. Generally, an anhydride and an acid are combined in a reactor with starch, which in some examples is starch derived from living organisms, and an esterification catalyst. The anhydride and the acid can be added separately to the reactor, or as shown in FIG. 1, it will be understood that the anhydride and the acid can first be reacted to form an acid anhydride, which can then be combined with the starch in the reactor. In some examples, additional anhydride may be added to the reactor before or during the reaction process.

[0025] Suitable anhydrides can include acetic anhydride, propionic anhydride, butyric anhydride, hexanoic anhydride, maleic anhydride, succinic anhydride, phthalic anhydride, hexenyl succinic anhydride, octenyl anhydride, and stearic anhydride, and mixtures thereof. The anhydride is, in one example, acetic anhydride.

[0026] The acid may be a carboxylic acid, one or more C 2~24 carboxylic acids and mixtures thereof. In some cases, the carboxylic acid is C 10 ~C 24 and mixtures thereof, and in some examples, may be lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, linoleic acid, linolenic acid, steridonic acid, oleic acid, and mixtures thereof. In some examples, the carboxylic acid is lauric acid, stearic acid, oleic acid, and mixtures thereof.

[0027] It is contemplated that the carboxylic acid can be a saturated or unsaturated fatty acid. Advantageous examples of the carboxylic acid can include fatty acids such as lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, linoleic acid, linolenic acid, steridonic acid, oleic acid, and mixtures thereof. In some examples, the carboxylic acid is lauric acid, stearic acid, oleic acid, and mixtures thereof.

[0028] As an example of first mixing and reacting an anhydride and an acid, acetic anhydride and lauric acid can be reacted according to the mechanism proposed below.

[0029] [Chemical formula]

[0030] It will be understood that in the equilibrium state, the following compounds may be present: acetic anhydride, lauric acid, lauroyl acetate anhydride, acetic acid, and lauric anhydride. Further, depending on the ratio of the anhydride to the acid, it is considered that the ratio of the resulting mixed acid anhydride (i.e., lauroyl acetate anhydride) changes.

[0031] It will be understood that the reaction of acetic anhydride with the other carboxylic acids described above proceeds according to the above reaction scheme, yielding the respective mixed acid anhydrides. Thus, the reaction of acetic anhydride and stearic acid yields acetic anhydride, stearic acid, stearoyl acetate anhydride, acetic acid, and stearic anhydride in the equilibrium state. Similarly, the reaction of acetic anhydride and oleic acid yields acetic anhydride, oleic acid, oleoyl acetate anhydride, acetic acid, and oleic anhydride in the equilibrium state. Considering the above reaction scheme, it should be noted that a reference or mention of a mixed acid anhydride as a reaction product of an anhydride and an acid includes, for example, in a specific reference to the reaction product of acetic anhydride and lauric acid, each of lauric acid, acetic acid, acetic anhydride, lauroyl acetate anhydride, and lauric anhydride.

[0032] Regarding starch, as described above, the compositions described herein are formed using starch derived from living organisms. As used herein and in the claims, the term "derived from living organisms" refers to a starch source that is a non-petroleum source. In other words, "derived from living organisms" refers to starch derived from plant sources and means excluding fossil-based starch. Starch derived from living organisms or its derivatives may also be referred to as starch or starch components. It will be understood that the term starch or starch components, as used herein and in the claims, refers to starch derived from living organisms or its derivatives, unless otherwise specified.

[0033] Starch (C6H 10 O5) n is a mixture of linear (amylose) and branched (amylopectin) polymers. Amylose is an essentially linear polymer of α(1→4)-linked D-glucopyranosyl units. Amylopectin is a highly branched polymer of D-glucopyranosyl units containing α(1→4) linkages with α(1→6) linkages at the branch points. The starch or starch component can be based on any native starch having an amylose content of 0 to about 100% and an amylopectin content of about 100 to 0%. In some examples, the amylose content is greater than about 50%, or about 60% to about 90%, or about 65% to about 85%, or about 70% to about 80%. In some embodiments, the amylose content is about 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, or about 90%. In some examples, the amylopectin content is about 10% to about 40%, or about 15% to about 35%, or about 20% to about 30%. In some embodiments, the amylopectin content is about 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or about 40%.

[0034] The starch component can be obtained from plants or cereal plants having barley, potato, wheat, rye, oats, pea, maize, corn, tapioca, sago, rice, cassava, arracacha, buckwheat, banana, kudzu, okra, sago, sorghum, sweet potato, taro, yam, broad bean, lentil, or other tubers. It may also be based on starch prepared from native starch by oxidation, hydrolysis, crosslinking, cationization, grafting, or etherification.

[0035] It is known that starch contains incorporated or inherent water or moisture in an amount of about 13% to about 20% by mass. As a result, when starch is dried by conventional methods, i.e., using heat, there is a risk of flammability, and the method described herein avoids this. In addition, drying in conventional methods can strengthen the hydrogen bonds in starch molecules, making it more difficult for subsequent esterification reactions to proceed. Therefore, the process described herein is intended to remove bound and free water by reacting starch with an anhydride (e.g., acetic anhydride) at room temperature, forming an acid (e.g., acetic acid), and reducing substantial starch degradation.

[0036] Referring back to FIG. 1, the starch mixed ester composition can be prepared in the presence of an esterification catalyst. Suitable esterification catalysts can be selected from (i) hydroxides and / or mineral acid salts or organic acid salts or carbonates of any metal selected from alkali metals, alkaline earth metals, and amphoteric metals (ii) organic interlayer transition catalysts, and (iii) amino compounds, and are exemplified below, for example.

[0037] Alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, lithium hydroxide; salts of organic acids and alkali metals such as sodium acetate, sodium propionate, sodium p-toluenesulfonate; alkaline earth metal hydroxides such as barium hydroxide, calcium hydroxide; salts of organic acids and alkaline earth metals such as calcium acetate, calcium propionate, barium p-toluenesulfonate; mineral acid salts such as sodium phosphate, calcium phosphate, sodium bisulfite, sodium bicarbonate, potassium sulfate; acidic salts or hydroxides of amphoteric metals such as sodium aluminate, potassium zincate, aluminum hydroxide, zinc hydroxide; carbonates such as sodium carbonate, potassium bicarbonate. Typically, the alkali metal hydroxide can be provided as an aqueous solution, for example, as a 50% aqueous solution of NaOH.

[0038] Amino compounds such as dimethylaminopyridine and dimethylaminoacetic acid.

[0039] Quaternary ammonium compounds such as N - trimethyl - N - propylammonium chloride and N - tetraethylammonium chloride.

[0040] By changing the amount of the mixed anhydride, the amount of starch, the amount of catalyst, and the reaction conditions, starch mixed esters with different degrees of substitution can be prepared. The ratio of the types of ester groups present in the starch mixed ester can vary greatly. When two different ester groups are present, they can be present in the range of about 20:1 to about 1:20.

[0041] The proposed reaction formula for the esterification of starch using a mixed anhydride is shown as follows: [Chemical formula]

[0042] In the above formula, x = 1 to 20 and y = 1 to 20; R1 is from acetic acid, propionic acid, butyric acid, hexanoic acid, maleic acid, succinic acid, phthalic acid, hexenyl succinic acid, octenyl acid, and stearic acid, and mixtures thereof, and R2 is a carboxylic acid, and in some cases may be C 2~24 carboxylic acid, and in some cases may be C 10 ~C 24 and in some examples may be lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, linoleic acid, linolenic acid, steridonic acid, oleic acid, and mixtures thereof. In some examples, R2 is from lauric acid, stearic acid, oleic acid, and mixtures thereof.

[0043] It will be appreciated that the starch mixed ester contains at least two, and in some cases three, different ester residues bonded to the same starch molecule. For this reason, the starch mixed ester contains both long-chain and short-chain carboxylic acid components. As an example, it is contemplated that the starch mixed ester may include a mixture of acetate and laurate, a mixture of acetate and stearate, a mixture of acetate and oleate, or a mixture of each mixture.

[0044] The total degree of substitution of the esterified starch may be in the range of about 0.1 to 2.9, and in some examples is greater than 1.0. Thus, in some examples, it is contemplated that the total degree of substitution may be from about 1.5 to about 2.9 or from about 1.8 to about 2.7 or from about 2.0 to about 2.5 or from about 2.2 to about 2.4. In some embodiments, the total degree of substitution may be about 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, about 2.9, or within any range that can be formed from each of the foregoing values. It is predicted that the starch mixed ester composition will exhibit a desired balance in mechanical properties, water resistance, processability, and biodegradation rate.

[0045] Generally, the degree of substitution of the acetate ester is from about 0.5 to about 2.4, or from about 0.6 to about 2.3 or from about 1.0 to about 2.2, or from about 1.6 to about 2.2. In some examples, the degree of substitution of the acetate ester is from about 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, about 2.2, or within any range that can be formed from each of the foregoing values. The degree of substitution of other ester residues (i.e., those from carboxylic acids such as, for example, laurate, stearate, oleate) can be from about 1 to about 2.5 or 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, or about 2.5. In some examples, the degree of substitution of other ester residues (i.e., those from carboxylic acids such as, for example, laurate, stearate, oleate) can be from about 0.01 to about 1.0, or about 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, about 2.5, or within any range that can be formed from each of the foregoing values.

[0046] The obtained starch mixed ester may have a glass transition temperature in the range of about 125°C to about 165°C. In some examples, the obtained starch mixed ester has a glass transition temperature of about 125°C, 126°C, 127°C, 128°C, 129°C, 130°C, 131°C, 132°C, 133°C, 134°C, 135°C, 136°C, 137°C, 138°C, 139°C, 140°C, 141°C, 142°C, 143°C, 144°C, 145°C, 146°C, 146°C, 148°C, 149°C, 150°C, 151°C, 152°C, 153°C, 154°C, 155°C, 156°C, 157°C, 158°C, 159°C, 160°C, 161°C, 162°C, 163°C, 164°C, or about 165°C.

[0047] According to one embodiment, a mixed anhydride is combined with starch to disperse the starch, and then a catalyst may be added such that the reaction occurs for a certain period of time at a temperature of about 100°C to about 200°C, or about 130°C to about 155°C. The resulting product can be cured in water (which may be effective for separating unreacted anhydride and fatty acid), and then the cured product can be finely ground, washed, neutralized, and dehydrated. Next, the dehydrated product can be dried to yield a dried product. Additionally, the dried and water-washed product may be washed with alcohol, which is intended to remove unreacted fatty acid and then dried. Alternatively, the dehydrated product may be introduced into an extruder for further processing, optionally in some cases together with additives or other biodegradable and / or compostable polymers, as will be described in more detail below. As yet another alternative, the product washed with water and alcohol can be dried and then intended to be blended with one or more biodegradable and / or compostable polymers.

[0048] Optional additives can include one or more elements selected from the group consisting of extenders; fillers; wood-derived materials; oxides of magnesium, aluminum, silicon, and titanium; alkali metal salts and alkaline earth metal salts; lubricants; release agents; acid removers; plasticizers; UV stabilizers; colorants; flame retardants; antioxidants; heat stabilizers; and mixtures thereof.

[0049] Turning now to FIG. 2, there is shown a proposed flow diagram of an alternative process scheme for making biodegradable and / or compostable compositions of bioderived starch mixed esters. In this process, an anhydride can be reacted with one or more carboxylic acids to form a mixed acid anhydride, which can then be mixed and reacted with bioderived starch and a catalyst to form a biodegradable and / or compostable composition of bioderived starch mixed esters. In some examples, the anhydride is acetic anhydride and the carboxylic acids are lauric acid, stearic acid, oleic acid, and mixtures thereof, which after reaction form a mixed acetic-fatty acid anhydride. Thus, the resulting mixed acid anhydride can include acetic-lauric anhydride, acetic-stearic anhydride, acetic-oleic anhydride, and mixtures thereof.

[0050] In one embodiment, a first mixed acid anhydride and a second mixed acid anhydride are formed separately and then mixed together before reacting this mixture with starch and a catalyst. In this regard, a first anhydride can be reacted with a first acid to form a first mixed acid anhydride. Additionally, a second anhydride can be reacted with a second acid to form a second mixed acid anhydride. The first anhydride and the second anhydride may be different, but they are generally the same and in the same case can be acetic anhydride. The first acid and the second acid are intended to be different. The first mixed acid anhydride and the second mixed acid anhydride are then mixed and then reacted with starch in the presence of a catalyst to form a biodegradable and / or compostable composition of starch mixed esters.

[0051] As an example, the first anhydride and the second anhydride can include anhydrides of acetic acid, propionic acid, butyric acid, hexanoic acid, maleic acid, succinic acid, phthalic acid, hexenyl succinic acid, octenyl acid, and stearic acid, and mixtures thereof. The first anhydride and the second anhydride may be the same or different. In some cases, the first anhydride and the second anhydride are the same, and in one example the first and second anhydrides are acetic anhydride.

[0052] The first acid and the second acid are different and each may be a carboxylic acid and C2~24 They may be carboxylic acids and mixtures thereof. In some cases, they are C 10 ~C 24 They may be carboxylic acids and mixtures thereof. In some cases, they may be lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, linoleic acid, linolenic acid, steridonic acid, oleic acid, and mixtures thereof. In some examples, the carboxylic acid is one of lauric acid, stearic acid, oleic acid, and mixtures thereof.

[0053] It is intended that the first carboxylic acid and the second carboxylic acid can be saturated or unsaturated fatty acids. Advantageous examples of the first carboxylic acid and the second carboxylic acid include lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, linoleic acid, linolenic acid, steridonic acid, oleic acid, and mixtures thereof. In some examples, the first carboxylic acid and the second carboxylic acid are different and are selected from lauric acid, stearic acid, and oleic acid. As described above, after separately forming the first mixed acid anhydride and the second mixed acid anhydride, the first mixed acid anhydride and the second mixed acid anhydride are mixed, and then reacted with starch in the presence of a catalyst to form a biodegradable and / or compostable composition of starch mixed ester.

[0054] In another embodiment, the first mixed acid anhydride, the second mixed acid anhydride, and the third mixed acid anhydride are separately formed, mixed together after formation, and then this mixture is reacted with starch. In this regard, each of the first, second, and third mixed acid anhydrides is different. According to this embodiment, the first anhydride may be reacted with the first acid to form the first mixed acid anhydride, the second anhydride may be reacted with the second acid to form the second mixed acid anhydride, and the third anhydride may be reacted with the third acid to form the third mixed acid anhydride. Each of the first, second, and third anhydrides may be different, but they are generally the same, and when they are the same, it may be acetic anhydride.

[0055] In some examples, each of the first, second, and third acids may be a carboxylic acid, C 2~24 it may be a carboxylic acid and mixtures thereof. In some cases, they are C 10 ~C 24 and in some examples, they may be lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, linoleic acid, linolenic acid, steridonic acid, oleic acid, and mixtures thereof. It is contemplated that the first, second, and third carboxylic acids may be saturated or unsaturated fatty acids. Advantageous examples of the first carboxylic acid, the second carboxylic acid, and the third carboxylic acid include lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, linoleic acid, linolenic acid, steridonic acid, oleic acid, and mixtures thereof. In some examples, the first, second, and third carboxylic acids are different and are selected from lauric acid, stearic acid, and oleic acid. As described above, after separately forming the first, second, and third mixed acid anhydrides, the first, second, and third mixed acid anhydrides are mixed and then reacted with starch in the presence of a catalyst to form a biodegradable and / or compostable composition of starch mixed esters.

[0056] Thereafter, the biodegradable and / or compostable composition of starch mixed esters may be cured in water (which may be effective to separate unreacted acid anhydrides and fatty acids), and then the cured product may be micronized, washed, neutralized, and dehydrated. Next, the dehydrated product can be dried to yield a dried product. In addition, the dried, water-washed product may be washed with alcohol, which is intended to remove unreacted fatty acids and then dried. Alternatively, the dehydrated product may be optionally introduced into an extruder for further processing, optionally with additives or other biodegradable and / or compostable polymers, as described in more detail below. As yet another alternative, the water- and alcohol-washed product may be dried and then blended with one or more biodegradable and / or compostable polymers.

[0057] Turning now to FIG. 3, an alternative process for preparing biodegradable and / or compostable compositions of starch mixed esters is shown. In this process, starch, a fatty acid, an acid anhydride, and a catalyst are fed into a reactor and reacted for a certain period of time under conditions suitable for dehydrating the starch. Thereafter, additional fatty acid and acid anhydride are added under suitable conditions for a specific time (e.g., at a temperature of about 100° C. to about 140° C. for 0.5 to 4 hours) to esterify the starch and form a biodegradable and / or compostable composition of starch mixed esters.

[0058] The resulting product may be cured in water (which may be effective for separating unreacted acid anhydride and fatty acid), and thereafter, the cured product may be micronized, washed, neutralized, and dehydrated. Next, the dehydrated product can be dried to yield a dried product. Additionally, the dried and water-washed product may be washed with alcohol, which is intended to remove unreacted fatty acid and then dried. Alternatively, the dehydrated product may optionally be fed into an extruder for further processing, optionally together with additives or other biodegradable and / or compostable polymers, as will be described in more detail below. As yet another alternative, the product washed with water and alcohol is dried and then may be intended to be blended with one or more biodegradable and / or compostable polymers.

[0059] Turning now to FIG. 4, a two-pot reaction scheme, i.e., a reaction scheme of two reactors for making a starch mixed ester composition, is shown. This process is described using stearic acid, acetic anhydride, and sodium hydroxide as representative examples of an acid, an acid anhydride, and a catalyst, respectively. In one reactor, acetic anhydride and starch are mixed with sodium hydroxide to dehydrate the starch and remove water from the sodium hydroxide solution to form acetic acid according to the following reaction.

[0060]

Chemical formula

[0061] This reaction can be carried out for about 1 hour to about 48 hours or for about 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, or 48 hours, or for any period within the range that can result from these values. This reaction can be carried out at a temperature of about 20°C to about 35°C or about 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, or about 35°C, or at any temperature within the range that can result from these values.

[0062] In another reactor, as shown below in the following reaction scheme, stearic acid and acetic anhydride are mixed and reacted under suitable conditions to form a mixed acid anhydride, namely acetic anhydride, stearic acid, stearoyl acetic anhydride, acetic acid, and stearic anhydride.

[0063]

Chemical formula

[0064] In this regard, suitable reaction conditions can include a reaction temperature of about 80°C to about 120°C, or about 90°C to about 110°C, or about 95°C to about 105°C. For this purpose, the temperature can be about 90°C, or about 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107, 108, 109, or about 110°C, or any range that can result from these values.

[0065] Similarly, the reaction time can be from about 15 minutes to about 360 minutes, or from about 30 minutes to about 300 minutes, or from about 45 minutes to about 240 minutes, or from about 50 minutes to about 120 minutes, or from about 55 minutes to about 90 minutes, or about 60 minutes. Therefore, the reaction time can be from about 45 minutes, or from about 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, or 90 minutes, or any range that can result from these values.

[0066] Thereafter, the mixed acid anhydride is mixed with the dehydrated starch and reacted under suitable conditions to form a starch mixed ester composition. Suitable reaction conditions include reacting at a temperature from about 125°C to about 165°C, or from about 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, or about 165°C, or any range that can result from these values. Therefore, the reaction time can be from about 1 to 15 hours or from about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, or about 15 hours, or any range that can result from these values.

[0067] Next, the starch mixed ester composition is washed with water to remove unreacted acetic anhydride, unreacted stearic acid, and acetic acid, and then dried to form a water-washed starch mixed ester composition. The dried water-starch mixed ester composition can be further processed by granulation, formation of articles, and / or blending with other biodegradable and / or compostable polymers (and additives) as shown and described in Figures 1 - 3.

[0068] In addition, or alternatively, the dried starch mixed ester composition may be further washed with alcohol, which removes unreacted stearic acid remaining after washing with water, and then the alcohol-washed starch mixed ester composition is dried to form an alcohol-washed starch mixed ester composition. The dried alcohol-starch mixed ester composition can be further processed, as shown and described in connection with FIGS. 1-3, by granulation, formation of articles, and / or blending with other biodegradable and / or compostable polymers (and additives), etc. The unreacted acetic anhydride, unreacted stearic acid, and acetic acid removed by water washing, and the unreacted stearic acid removed by alcohol washing if carried out, may be sent for further processing or treatment for reuse or other purposes.

[0069] Turning now to FIG. 5, a single pot reaction scheme, i.e., a reaction scheme of a single reactor for making a starch mixed ester composition, is shown. This process is described using stearic acid, acetic anhydride, and sodium hydroxide as representative examples of an acid, an acid anhydride, and a catalyst, respectively. In the reactor, acetic anhydride and starch are mixed with an aqueous sodium hydroxide solution, the starch is dehydrated, and water is removed from the sodium hydroxide by reaction to form acetic acid.

[0070] Suitable reaction conditions include reacting at a temperature of about 20°C to about 35°C or about 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, or about 35°C, or any range of temperatures that can result from these values. The reaction can be carried out for a fixed period in the range of about 1 minute to about 60 minutes, or about 5 minutes to about 30 minutes or about 10 minutes to about 20 minutes or about 15 minutes. In some examples, the reaction can be carried out for a fixed period of about 5 minutes or about 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or about 25 minutes, or any range of temperatures that can result from these values.

[0071] Based on 100 grams of corn starch (in some examples, high amylose corn starch) which is about 0.62 mol, the amount of acetic anhydride added to the reactor is about 1.0 mol to about 2.0 mol, or about 1.0, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, or about 2.0 mol. The amount of sodium hydroxide added to the reactor is about 0.05 mol to about 0.15 mol, or about 0.06, 0.07, 0.08, 0.09, 0.10, 0.11, 0.12, 0.13, or about 0.15 mol.

[0072] At the end of the reaction, i.e., at the end of the above reaction time, stearic acid and an additional amount of acetic anhydride are added to the reactor and reacted under suitable conditions to form a starch mixed ester composition. In this regard, the amount of stearic acid is about 0.1 to about 0.6 mol, or about 0.1, 0.2, 0.3, 0.4, 0.5, or about 0.6 mol. The amount of additional acetic anhydride added to the reactor can be about 0.5 mol to 1.5 mol or about 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, or about 1.5 mol.

[0073] Based on the previous description, those skilled in the art will understand that when a large amount of corn starch is used, the amounts of acetic anhydride (in each of the dehydration and esterification steps), sodium hydroxide, and stearic acid will be increased accordingly.

[0074] Suitable reaction conditions may include a reaction temperature of about 100°C to about 180°C, or about 110°C to about 170°C, or about 115°C to about 160°C. For this purpose, the temperature can be about 100°C, or about 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, or about 180°C, or any range that can result from these values.

[0075] The reaction time can be about 30 minutes to about 360 minutes, or about 60 minutes to about 300 minutes, or about 90 minutes to about 240 minutes, or about 100 minutes to about 180 minutes, or about 110 minutes to about 150 minutes, or about 120 minutes. For this purpose, the reaction time can be from about 100 minutes, or about 101, 102, 103, 104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, or about 140 minutes, or any range that can result from these values.

[0076] Next, the starch mixed ester composition is washed with water to remove unreacted acetic anhydride, unreacted stearic acid, and acetic acid, and then dried to form a water-washed starch mixed ester composition. The dried water-starch mixed ester composition can be further processed, as shown and described in connection with FIGS. 1-3, by granulation, formation of articles, and / or blending with other biodegradable and / or compostable polymers (and additives).

[0077] In addition, or alternatively, the dried starch mixed ester composition may be further washed with alcohol, which removes unreacted stearic acid remaining after the water wash, and then the alcohol-washed starch mixed ester composition is dried to form an alcohol-washed starch mixed ester composition. The dried alcohol-starch mixed ester composition can be further processed, as shown and described in connection with FIGS. 1-3, by granulation, formation of articles, and / or blending with other biodegradable and / or compostable polymers (and additives). The unreacted acetic anhydride, unreacted stearic acid, and acetic acid removed by the water wash, and the unreacted stearic acid removed by the alcohol wash if carried out, may be sent for further processing or treatment for reuse or other purposes.

[0078] <Blend of starch mixed ester and other biodegradable and / or compostable polymers> As suggested above, it is intended that the biodegradable and / or compostable compositions of the starch mixed esters described herein can be blended with one or more other biodegradable and / or compostable polymers to form a blend composition. The blend can be prepared by mixing or melt processing using an extruder or similar device, as shown in FIGS. 1-3.

[0079] In this regard, the blend can include from about 20% to about 90% of the starch mixed ester composition described herein, and from about 10% to about 80% of at least one other biodegradable and / or compostable polymer. For example, the starch mixed ester composition described herein can be present in the blend in an amount of about 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or about 90%. The at least one other biodegradable and / or compostable polymer can be present in the blend in an amount of about 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or about 80%.

[0080] Regarding the starch mixed ester composition, it is intended that the starch mixed ester composition blended with the at least one other biodegradable and / or compostable polymer can be the starch mixed ester composition before washing with water, after washing with water, or after washing with alcohol. In each case, the starch mixed ester composition is typically dried before blending. When the starch mixed ester composition is blended after washing with water and drying, the amount of unreacted fatty acid (e.g., stearic acid) can range from about 20% to about 40% relative to the starch mixed ester composition. For this purpose, the amount of unreacted fatty acid (e.g., stearic acid) present in the starch mixed ester composition can be about 20%, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, or about 40%.

[0081] At least one other biodegradable and / or compostable polymer in the blend can be a biodegradable and / or compostable polymer of starch, and may also include biodegradable and / or compostable polymers such as polylactide (PLA), poly(hydroxybutyrate) (PHB), polycaprolactone (PCL), polyhydroxybutyrate valerate (PHB-V), poly(β-hydroxyalkanoate) (PHA), poly(1,4-butylene succinate) (PBS), polybutylene adipate terephthalate (PBAT), poly(vinyl alcohol) (PVA), cellulose-based ester derivatives, or mixtures thereof.

[0082] In some embodiments, at least one other biodegradable and / or compostable polymer has the following general formula: (1) HO-(C n H 2n )-COOH (wherein n is an integer from 1 to 21, preferably an integer from 1 to 7, more preferably 1, 2, 3, 4 or 5) and can be a linear polyester derived from a hydroxyl-carboxylic acid having the formula.

[0083] Such acids are, for example, glycolic acid (n = 1), lactic acid (n = 2 and the hydroxyl group is fixed in the alpha position), hydroxybutyric acid and hydroxyisobutyric acid (n = 3), hydroxyvaleric acid (n = 4), hydroxycaproic acid (n = 5), and in each case the hydroxy group is fixed in the terminal position.

[0084] Methods for preparing such types of linear polyesters derived from such hydroxycarboxylic acids are known in the art. Many of these hydroxycarboxylic acids are known to form cyclic esters, i.e., lactones, which are preferably used in the production of the corresponding polyesters. Hydroxycaproic acid forms a cyclic ester known as 6-caprolactone, which can be polymerized as such. Such lactones are known. Preferred among such polylactones is poly(6-caprolactone).

[0085] The linear polyester used in the present invention is derived from a combination of a diacid and a diol and has the following formula: [Chemical formula] (wherein R is an aliphatic hydrocarbon residue having 2, 4, or 6 carbon atoms; R' is an aliphatic saturated or unsaturated divalent hydrocarbon residue having 2 to 22 carbon atoms) and can be described by:

[0086] Examples of suitable linear polyesters have the following formula: [Chemical formula] (wherein x is 2 (poly(ethylene succinate)) or x is 4 (polyethylene adipate)) and can be described by: The linear polyester used in the present invention can be derived, as described above, from hydroxycarboxylic acids or mixtures of such acids, or the corresponding lactones or mixtures of such lactones. The linear polyester may also be a physical mixture of different polyester species. Examples of such linear polyesters include poly(3 - propiolactone), poly(5 - valerolactone), poly(6 - caprolactone), poly(6 - decalactone), poly(7 - enantholactone), poly(8 - caprylolactone), poly(12 - laurolactone), poly(15 - pentadecanolactone), poly(hydroxybutyrate), poly(hydroxyvalerate).

[0087] Plasticizers are intended to be added to the blend composition to provide improved processability of the material and flexibility of the product. Molded articles and films prepared from the blend composition can be modified by mixing with a variety of solvent-based low molecular weight ester plasticizers. An obvious requirement for these plasticizers is that they be biodegradable and / or compostable. Examples of such plasticizers include phthalic esters (dimethyl-, diethyl-, dipropyl-, dibutyl-, dihexyl-, diheptyl-, dioctyl-, etc.), dimethyl- and diethyl succinate esters and related esters, glycerol triacetate (triacetin), glycerol mono- and diacetate, glycerol mono-, di- and tripropionate, glycerol tributanoate (tributyrin), glycerol mono- and dibutanoate, glycerol mono-, di-, and tristearate, and other related glycerol esters, lactate esters, citrate esters, adipate esters, stearate esters, oleate esters, ricinoleate esters, other fatty acid esters, erucic acid esters, soybean oil, castor oil, and various other biodegradable and / or compostable esters such as various esters known in the chemical art.

[0088] Inorganic and organic fillers can be included in the blend composition to extend the range of properties of the molded article. Such inorganic fillers include talc (hydrated magnesium silicate), titanium dioxide, calcium carbonate, clay, sand, chalk, limestone, diatomaceous earth, silicate, boron nitride, mica, glass, quartz, and ceramic, and biodegradable and / or compostable organic fillers such as starch, cellulose, wood flour and fibers, pecan fibers, and other well-known inorganic and organic filler materials.

[0089] As described above, the blend is formed by co-extruding a starch blend ester composition with a biodegradable and / or compostable polymer, and additives, which may result in, for example, pellets of the blend, which can then be formed into articles or manufactured products such as films and other molded articles.

[0090] <Manufactured article> Biodegradable and / or compostable compositions of starch mixed esters, and blends of biodegradable and / or compostable compositions of starch mixed esters with one or more other biodegradable and / or compostable polymers, are intended to be processed by various methods known in the art, such as extrusion, injection molding, compression molding, film forming, blow molding, vacuum forming, thermoforming, extrusion molding, coextrusion, foaming, profile extrusion, combinations thereof, and other known intended methods, but not limited thereto. In this regard, the starch mixed ester composition can be formed into articles such as, but not limited to, inks, paints, compost bags, laminated bags, agricultural films, binders for ceramics, landscape stakes or spikes, bottles, threads, sheets, films, packaging materials, pipes, tubes, lids, cups, rods, laminated films, sacks, bags, cutlery, pharmaceutical capsules, foams, granules, and powders.

[0091] Starch mixed ester compositions, and blends of starch mixed ester compositions with one or more other biodegradable and / or compostable polymers, can also be (1) Films and sheets formed by extrusion, casting, rolling, inflation, etc. (2) Laminating and coating on paper, sheets, films, non-woven fabrics, etc. (3) Additives incorporated into paper during the papermaking process to impart special functions to paper and paper products. (4) Additives incorporated into non-woven fabrics during their manufacturing process to impart special functions to non-woven fabrics and their products. (5) Aqueous emulsions or suspensions for use in paints, inks, etc. (6) Solid molded products such as garden stakes produced by injection molding, extrusion molding, blow molding, transfer molding, compression molding, etc. And there can also be uses such as these.

Examples

[0092] The following examples can provide additional details about the compositions and methods described herein based on the present disclosure.

[0093] <Example 1> 225 g of acetic anhydride and 150 g of lauric acid were placed in a 1 L separable flask, heated, and stirred at 60 °C for 2 hours to form acetic-lauric anhydride, and then it was mixed with 150 g of high amylose corn starch (having an amylose content of about 75%) to disperse the corn starch. Then, 51.8 g of a catalyst in the form of 35% sodium hydroxide was added. The temperature was raised to 145 °C, and the mixture was stirred for 4 hours while refluxing. Then, the mixture was cooled to 120 °C, 225 g of acetic anhydride was added, and the mixture was stirred at 130 °C for 1 hour.

[0094] The resulting viscous liquid was placed in water to cure. The cured mass was finely ground in water, and the fine grinding was repeated several times to produce small particles. After washing with water, the product was reslurried and neutralized to pH 4 - pH 7 using sodium hydroxide. The neutralized product was dehydrated and dried overnight at 80 °C. The dry powder was reslurried in ethanol to wash away the unreacted lauric acid, and the target compound was recovered by suction filtration. This operation was repeated twice to remove lauric acid.

[0095] The recovered product was finely ground in water, washed with water, dehydrated, and dried at 80 °C to obtain the desired starch mixed ester composition.

[0096] <Example 2> High amylose corn starch (having an amylose content of about 75%) was mixed with acetic anhydride in an amount such that about 2 moles of acetic anhydride were supplied per 1 mole of water in the high amylose starch. The mixture was stirred for 24 hours to remove the water in the starch. The product was suction filtered and dried under reduced pressure in a dryer for 24 hours.

[0097] Stearic acid (200 g) and acetic anhydride (200 g) were mixed at 100 °C for 1 hour with stirring to form a mixed acid anhydride. The mixed acid anhydride was cooled to 60 °C and mixed with dried high amylose starch. Then, the catalyst DMAP (12 g) was dissolved in acetic anhydride (50 g) and added dropwise at about 2 - 3 drops / second.

[0098] After the addition of the catalyst was completed, the temperature was raised to 145 °C and the reaction was carried out for 4 hours with stirring. Then, the mixture was cooled to 60 °C to allow the addition of additional acetic anhydride (150 g). At the completion of this addition, the temperature was raised again to 145 °C and the reaction was continued with stirring for another 4 hours, at which point the reaction was considered complete.

[0099] After the completion of the reaction, the temperature was lowered to 60 °C, and the viscous reaction product was put into water at 60 °C to harden (solidify) the reaction product. Then, it was finely pulverized, filtered, and dehydrated to obtain the desired starch mixed ester composition.

[0100] <Example 3> High amylose corn starch (having an amylose content of about 75%) was mixed with NaOH and acetic anhydride in an amount sufficient to supply about 2 moles of acetic anhydride per mole of water in the high amylose starch. The mixture was stirred for 24 hours to remove the water in the starch.

[0101] Stearic acid (100 g) and acetic anhydride (100 g) were mixed at 100 °C for 1 hour with stirring to form a mixed acid anhydride. The high amylose corn starch was heated to 60 °C together with acetic anhydride and 50% aqueous NaOH solution, and the mixed acid anhydride was added. After the addition of the mixed acid anhydride was completed, the temperature was raised to 120 °C and the reaction was carried out for 7 hours with stirring, at which point the reaction was considered complete.

[0102] After the reaction was completed, the viscous reaction product was put into water to cure (solidify) the reaction product. Then, it was finely pulverized, filtered, and dehydrated to obtain the desired mixed ester composition. The obtained viscous liquid was put into water to cure. The cured mass was finely pulverized in water, and the fine pulverization was repeated several times to generate small particles. After washing with water, the product was reslurried with water until the pH reached about 6 to about 7. The neutralized product was dehydrated and dried overnight at 80 °C. The dry powder was reslurried in ethanol to wash away and remove the unreacted stearic acid, and the target compound was recovered by suction filtration. This operation was repeated twice to remove the stearic acid.

[0103] Several batches of starch mixed ester compositions were prepared according to the method described in Example 3, and the glass transition temperature and degree of substitution (DS) were measured. Table 1 shows the results.

[0104]

Table 1

[0105] <Example 4> The method of Example 3 above was repeated except that stearic acid was replaced with either oleic acid or lauric acid (in the same molar amount as stearic acid). The glass transition temperature and degree of substitution (DS) were measured. Table 2 shows the results.

[0106]

Table 2

[0107] <Example 5> A starch mixed ester composition was prepared according to the process shown in Figure 5 and described above. Table 3 shows the data regarding the test conditions and the analysis of the obtained starch mixed ester composition.

[0108]

Table 3

[0109] <Example 6> The starch mixed ester composition was prepared according to the process shown in FIG. 5 and described above. Thermogravimetric analysis (TGA) was performed on a sample of starch acetate stearate made according to the method shown and described in connection with FIG. 5. Referring to FIG. 6A, thermogravimetric analysis (TGA) was performed on a sample of starch acetate stearate made according to the method shown and described in connection with FIG. 5 and washed with water. FIG. 6B shows the results of thermogravimetric analysis (TGA) performed on a sample of starch acetate stearate made according to the method shown and described in connection with FIG. 5 and washed with ethanol. FIG. 6C shows the results of thermogravimetric analysis (TGA) performed on a sample of high amylose corn starch used to make the starch acetate stearate tested in FIGS. 6A and 6B.

[0110] For a sample of starch acetate stearate made according to the method shown and described in connection with FIG. 5 1 1H-NMR analysis was performed. A sample for NMR (nuclear magnetic resonance) measurement was prepared by dissolving approximately 30 mg of the sample in 0.7 ml of DMSO-d6, and this mixture was transferred to a 5 mm NMR tube using a glass Pasteur pipette. NMR measurements were performed at 50 °C on a Bruker Advance Spectrometer (500 MHz). The residual DMSO signal was used as an internal standard in the measurement.

[0111] FIG. 7A is of a sample of starch acetate stearate made according to the method shown and described in connection with FIG. 5 and washed with water 1The H-NMR analysis is shown. Resonances of the starch backbone, anomeric protons, and unsubstituted hydroxyl groups (designated 1 - 9) can be seen in the 3.3 - 5.9 ppm region. Signals corresponding to the methine protons of stearic acid (designated 13 - 26) are seen at around 1.24 ppm. Signals corresponding to the methyl protons of stearic acid (designated 27) and the methyl protons of acetic anhydride (designated 10) are seen in the regions of 0.84 ppm and 1.8 - 2.3 ppm, respectively. In addition, there is a broad signal appearing in the 10.7 - 12.8 ppm region, which corresponds to the carboxylic acid group of stearic acid (* designated). This serves as confirmation of the presence of unreacted stearic acid in the water-washed sample.

[0112] Figure 7B is of a sample of stearic acid acetate starch washed with ethanol, made according to the method shown and described in relation to Figure 5 1 The H-NMR analysis is shown. Resonances of the starch backbone, anomeric protons, and unsubstituted hydroxyl groups (designated 1 - 9) can be seen in the 3.3 - 5.9 ppm region. Signals corresponding to the methine protons of stearic acid (designated 13 - 26) are seen at 1.24 ppm. Signals corresponding to the methyl protons of stearic acid (designated 27) and the methyl protons of acetic anhydride (designated 10) are seen in the regions of 0.84 ppm and 1.8 - 2.3 ppm, respectively. In addition, the broad signal corresponding to the carboxylic acid group disappears in the sample washed with ethanol, which serves as confirmation that unreacted stearic acid was removed after ethanol washing of stearic acid acetate starch.

[0113] Figure 7C is of a sample of high amylose corn starch used to make the stearic acid acetate starch tested in Figures 7A and 7B 11H-NMR analysis is shown. The resonance of the starch chain protons (designated 2 - 6) can be readily confirmed in the region of 3.5 - 3.9 ppm. The anomeric proton corresponding to the internal α-1,4 linkage (designated 1), and the methyl protons corresponding to the OH groups of the starch are found in the region of 4.25 - 5.5 ppm. The signal of the residual water peak is present at 3.28 ppm, which appears due to the hygroscopicity of both starch and DMSO.

[0114] For a sample of starch acetate stearate made according to the method shown and described in relation to Figure 5 13 13C-NMR analysis was carried out. A sample for NMR (nuclear magnetic resonance) measurement was prepared by dissolving approximately 30 mg of the sample in 0.7 ml of DMSO-d6, and this mixture was transferred to a 5 mm NMR tube using a glass Pasteur pipette. NMR measurement was carried out at 50 °C on a Bruker Advance Spectrometer (500 MHz). The residual DMSO signal was used as an internal standard in the measurement.

[0115] Figure 8A shows the 13C-NMR analysis of a sample of starch acetate stearate made according to the method shown and described in relation to Figure 5 and washed with water. 13 13C-NMR analysis is shown. 13As observed from the 13C-NMR spectrum, signals corresponding to the starch backbone and anomeric carbons are found in the 60 - 98 ppm region (designated as 1 and 2 - 4). Signals due to the secondary carbons of the alkyl chain of stearic acid (designated as 11 - 26) are found in the region of 21.2 - 34.3 ppm. Further, the signal corresponding to the primary carbon of stearic acid (designated as 27) and the signal corresponding to the primary carbon of acetic anhydride (designated as 10) are found at 13.7 ppm and 20.2 ppm, respectively. The resonance of the carbonyl carbon of stearic acid (designated as 28) and the resonance of the carbonyl carbon of acetic anhydride (designated as 30) are found at 169.1 ppm and 169.8 ppm, respectively. Further, the signal at 174.1 ppm is due to the carboxylic acid group (*) present in stearic acid, which also serves as confirmation of the presence of unreacted stearic acid in the sample washed with water.

[0116] Figure 8B shows the 13C-NMR analysis of a sample of starch stearate acetate washed with ethanol, made according to the method shown and described in relation to Figure 5. 13 C-NMR analysis is shown. 13 As observed from the 13C-NMR spectrum, signals corresponding to the starch backbone and anomeric carbons are found in the 60 - 98 ppm region (designated as 1 and 2 - 4). A sharp signal due to the secondary carbons of the alkyl chain of stearic acid (designated as 14 - 24) is found around 28.7 ppm. Further, the signal corresponding to the primary carbon of stearic acid (designated as 27) and the signal corresponding to the primary carbon of acetic anhydride (designated as 10) are found at 13.7 ppm and 20.2 ppm, respectively. The resonance of the carbonyl carbon of stearic acid (designated as 28) and the resonance of the carbonyl carbon of acetic anhydride (designated as 30) are found at 169.1 ppm and 169.8 ppm, respectively. Further, the signal corresponding to the carboxylic acid group of stearic acid disappears, which in turn serves as confirmation that unreacted stearic acid was removed during the ethanol washing of starch stearate acetate.

[0117] Figure 8C shows the 13 C-NMR analysis of the sample of high amylose corn starch used to make stearic acid acetate starch tested in Figures 8A and 8B. 13 As observed from the C-NMR spectrum, the resonance of the starch chain carbon (labeled 2 - 6) is confirmed in the region of 60 - 80 ppm. The anomeric carbon corresponding to the internal α-1,4 bond (labeled 1) is seen at around 100 ppm.

[0118] <Example 8> A blend of stearic acid acetate starch and PBAT was produced by the following method. PBAT was fed into a multi-zone Leistritz twin-screw extruder operating at a screw speed of approximately 100 rpm with a feed rate of 1 kg / h. The extruder had the following temperature profile: 131 °C die temperature and 145 °C / 155 °C / 180 °C / 180 °C / 185 °C / 185 °C / 180 °C / 180 °C / 160 °C / 145 °C. After feeding PBAT for a certain period (about 15 - 20 minutes), the feeding of the stearic acid acetate starch composition washed (and dried) with water was started at a rate of 1 kg / h. The blend coming out of the die (which contains stearic acid acetate starch and PBAT in approximately equal parts) was collected and sent to a water bath, and samples were collected after about 7 - 10 minutes, 10 - 20 minutes, and 20 - 25 minutes. Then, the blend was pelletized. Each sample was analyzed using thermogravimetric analysis (TGA), derivative thermogravimetric analysis (DTG), and differential scanning calorimetry (DSC), and the results are shown in Tables 4 and 5. Then, the blend was pelletized.

[0119] <Example 9> The blend described in Example 8 was repeated except that the feed rates were adjusted so that the acetic acid stearic acid starch composition was fed at about 0.6 kg / h and PBAT was fed at about 1.4 kg / h. As a result, a blend containing about 30% acetic acid stearic acid starch and about 70% PBAT was formed. Similar to Example 8, the blend exiting the die was collected, sent to a water bath, and samples were collected after about 20 - 30 minutes. Thereafter, the blend was pelletized. The samples were analyzed using thermogravimetric analysis (TGA), derivative thermogravimetric analysis (DTG), and differential scanning calorimetry (DSC), and the results are shown in Tables 4 and 5.

[0120]

Table 4

[0121]

Table 5

[0122] <Example 10> Kraft paper (86 gsm) alone, and high amylose corn starch, corn starch, acetic acid starch, made according to the method shown and described with respect to Figure 5, and coated with acetic acid stearic acid starch washed with water (using the rod coating method), in accordance with ASTM D3285-93 (Standard Test Method for Water Absorbency of Non-Vibras Paper and Board Papers), a Cobb test was carried out for 120 seconds. The starch is high amylose corn starch, made according to the method shown and described with respect to Figure 5, and is acetic acid stearic acid starch washed with ethanol. The starch is high amylose corn starch, made according to the method shown and described with respect to Figure 5, and is acetic acid stearic acid starch washed with water. The starch is normal (non-high amylose) corn starch, made according to the method shown and described with respect to Figure 5, and is acetic acid stearic acid starch washed with ethanol. The starch was normal (non-high amylose) corn starch and PLA. A PLA coating solution was prepared by mixing PLA and ethyl acetate to form a 5% (wt / vol) solution of PLA in ethyl acetate. The sample was mixed in acetonitrile, and another coating solution was prepared by forming a 5% (wt / vol) solution of the sample in acetonitrile.

[0123] The results are shown in Figure 9, and it can be seen that biodegradable and / or compostable compositions of each starch mixed ester achieved Cobb values similar to those of PLA when the coating mass was about 3 - 5 g / m 2 It can be understood that there is little or no difference in Cobb values when comparing biodegradable compositions of starch mixed esters washed with water with biodegradable and / or compostable compositions of starch mixed esters washed with ethanol, and when comparing biodegradable and / or compostable compositions of starch mixed esters made with high amylose starch with those made with normal corn starch.

[0124] The concepts of the present disclosure are susceptible to various modifications and alternative forms, but specific exemplary embodiments of the present disclosure are shown by way of example in the figures. However, it is not intended to limit the concepts of the present disclosure to the specific disclosed forms; it will be understood that it is intended to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the claims.

[0125] Generally, biodegradable compositions of starch mixed esters derived from biological sources are described, including mixed starch mixed esters having a total degree of substitution of at least 1.0, wherein the substituents include (a) acetate esters and (b) a mixture with one of lauric acid ester, stearic acid ester, oleic acid ester, or a mixture thereof, and the degree of substitution of (a) is greater than that of (b).

[0126] Aspects of the invention are also set forth in the following series of numbered clauses. Clause 1. A biodegradable composition of a starch mixed ester derived from a biological source, comprising a mixed starch mixed ester having a total degree of substitution of at least 1.0, wherein the ester substituents are (a) acetate esters and (b) one or more C 10 ~C 24 A mixture of ester residues, and the degree of substitution of (a) is greater than that of (b). Clause 2. The composition according to Clause 1, wherein the one or more C 10 ~C 24 The ester residues are selected from the group consisting of lauric acid ester, stearic acid ester, oleic acid ester, or a mixture thereof. Clause 3. The composition according to Clause 1, having a glass transition temperature of about 125 °C to about 165 °C. Clause 4. The composition according to Clause 1, 2, or 3, wherein the starch mixed ester has a total degree of substitution of 1.5 to about 2.9. A method for preparing a biodegradable composition of a starch mixed ester derived from a biological source having a total substitution degree of at least 1.0, comprising the step of reacting starch with a mixed acid anhydride to form a starch mixed ester composition, wherein the mixed acid anhydride is formed from (a) an acid anhydride and (b) a carboxylic acid having 10 to 24 carbon atoms. The method according to clause 5, wherein the acid anhydride is acetic anhydride. The method according to clause 5 or 6, wherein the carboxylic acid is selected from the group consisting of lauric acid, stearic acid, oleic acid, or a mixture thereof. The method according to any one of clauses 5 to 7, wherein the starch is reacted in the presence of an esterification catalyst. The method according to clause 8, wherein the esterification catalyst is an alkali metal hydroxide or an amino compound. Clause 10. a. Reacting sodium hydroxide, acetic anhydride, and starch in a first reactor; b. Reacting stearic acid and acetic anhydride in a second reactor to form a mixed acid anhydride; c. Reacting the contents of the first reactor with the contents of the second reactor to esterify the starch and form a starch mixed ester composition. The method according to clause 5, further comprising the above steps. Clause 11. Reacting sodium hydroxide, acetic anhydride, and starch in a reactor to dehydrate the starch and form a mixture; then adding stearic acid and acetic anhydride to the mixture to esterify the starch and form a starch mixed ester composition. The method according to clause 5. The method according to any one of clauses 5 to 11, wherein the starch is high amylose content starch. The method according to any one of clauses 5 to 12, further comprising the step of washing the starch mixed ester composition with water and then drying it to form a washed starch mixed ester composition. Clause 14. The method according to clause 13, further comprising the step of washing the washed starch mixed ester with alcohol to form an alcohol-washed starch mixed ester composition following the water washing. Clause 15. The method according to clause 13 or 14, further comprising the step of drying the washed starch mixed ester composition.

[0127] The present invention has been described above purely by way of example, and it will be understood that modifications in detail may be made within the scope of the present invention. Each feature is disclosed in this description and may be provided independently or in any suitable combination, where appropriate, in the claims and the drawings. The reference numerals appearing in the claims are for illustrative purposes only and have no effect of limiting the claims.

Claims

1. A method for producing a biodegradable and / or compostable composition of a bio-derived starch mixed ester having a total substitution degree of at least 1.0, comprising the following steps: A step of preparing a mixed acid anhydride by reacting an acid anhydride with a carboxylic acid having 10 to 24 carbon atoms; Subsequently, the mixed acid anhydride and starch are reacted in the presence of an esterification catalyst selected from alkali metal hydroxides and amino compounds to form a starch mixed ester composition. Methods that include...

2. The step of reacting the starch with the mixed acid anhydride further comprises the following steps: a. A step of reacting sodium hydroxide, acid anhydride, and starch in a first reactor; b. A step of reacting an acid anhydride with a carboxylic acid having 10 to 24 carbon atoms in a second reactor in the presence of an esterification catalyst to form the mixed acid anhydride; c. A step of reacting the contents of the first reactor with the contents of the second reactor to esterify the starch and form the starch mixed ester composition. The method according to claim 1, including the method described in claim 1.

3. The method according to claim 1 or 2, wherein the acid anhydride is acetic anhydride.

4. The method according to claim 1 or 2, wherein the carboxylic acid is selected from the group consisting of lauric acid, stearic acid, oleic acid, and mixtures thereof.

5. The method according to claim 1 or 2, wherein the starch is a high-amylose-containing starch.

6. The method according to claim 1 or 2, further comprising the step of washing the starch mixed ester composition with water, and then drying it to form a water-washed starch mixed ester composition.

7. The method according to claim 6, further comprising the step of washing with water, followed by washing the water-washed starch mixed ester with alcohol to form an alcohol-washed starch mixed ester composition.

8. The step of reacting the starch with the mixed acid anhydride is the following: A step of mixing an acid anhydride, starch, and sodium hydroxide to form a mixture, and dehydrating the starch; Subsequently, a step is taken to add a fatty acid having 10 to 24 carbon atoms and an additional acid anhydride to the mixture to esterify the starch and form the starch mixed ester composition. The method according to claim 1, including the method described in claim 1.

9. The method according to claim 8, wherein the starch is a high-amylose-containing starch.

10. The method according to claim 8, further comprising the step of washing the starch mixed ester composition with water, and then drying it to form a water-washed starch mixed ester composition.

11. The method according to claim 10, further comprising the step of washing with water, followed by washing the water-washed starch mixed ester with alcohol to form an alcohol-washed starch mixed ester composition.

12. The method according to claim 1 or 2, wherein the starch mixed ester has a degree of substitution of acetate ester of 0.5 to 2.6 and a degree of substitution of carboxylic acid ester of 0.01 to 2.4, and the total degree of substitution is 1.5 to 2.

9.

13. The method according to claim 1 or 2, wherein the starch mixed ester has a glass transition temperature of 125°C to 165°C.

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