Starch-based composite materials, their preparation methods and applications, and plastic products

Abstract

The present invention relates to a starch-based composite material, a preparation method and application thereof, and a plastic product. The components of the starch-based composite material include: a polyester material, starch and a polyhydroxy compound; wherein, based on the total mass of the polyester material and the starch, the mass ratio of the polyester material is 15% to 85%, and the mass ratio of the starch is 15% to 85%; the mass of the polyhydroxy compound is 10% to 50% of the mass of the starch; the average particle size of the starch is ≤1 μm.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, in particular to a starch-based composite material, a preparation method and application thereof, and a plastic product. Background Art

[0002] With the awakening of people's environmental protection awareness, the research on "green polymers" to replace general petrochemical plastics has gradually attracted the attention of researchers. Technicians often modify resins with biodegradable biomaterials to obtain biodegradable materials. Among them, starch has the characteristics of a wide variety of varieties, rich sources and low price, and is also easily eroded by microorganisms and can provide nutrients for microorganisms. The final products of biodegradation are carbon dioxide and water, which will not pollute the environment. Therefore, starch is often used in the preparation of biodegradable materials, providing a good way to solve white pollution.

[0003] However, since starch is a polyhydroxy natural macromolecular compound, hydrogen bonds interact with each other within and between adjacent molecules to form a microcrystalline structure. In the traditional blending process, this structure is not easy to change and lacks plasticity, resulting in poor compatibility with the substrate material. When used to modify resins to prepare biodegradable materials, it often has an adverse effect on the mechanical properties such as the toughness of the resin. Especially in the film state, its toughness cannot meet the required standards in related application fields, thus limiting its application scope.

[0004] Therefore, the traditional technology still needs to be improved. Summary of the Invention

[0005] Based on this, the present invention provides a starch-based composite material with excellent toughness, a preparation method and application thereof, and a plastic product.

[0006] In the first aspect of the present invention, a starch-based composite material is provided. The components of the starch-based composite material include: a polyester material, starch, and a polyhydroxy compound;

[0007] Wherein, based on the total mass of the polyester material and the starch, the mass ratio of the polyester material is 15% - 85%, and the mass ratio of the starch is 15% - 85%;

[0008] The mass of the polyhydroxy compound is 10% - 50% of the mass of the starch;

[0009] The average particle size of the starch ≤ 1 μm.

[0010] The above-mentioned starch-based composite material has excellent toughness. Even in the state with a thickness < 16 μm, it can still maintain excellent toughness: the elongation at break > 250%, among the 100% directional tensile strength, the transverse tensile strength > 5 MPa, and the longitudinal tensile strength > 10 MPa. At the same time, in the state with a thickness ≥ 16 μm, it can maintain good transparency. When used to prepare plastic products, it can improve the service life of the products and is conducive to broadening its application range.

[0011] Although the mechanism is not yet clearly understood, the inventors of this application speculate that it is because: in the above-mentioned starch-based composite material, on the one hand, polyhydroxy compounds are used to reduce the content of hydrogen bonds within and between starch molecules, increase the degree of freedom of starch molecular chains, plasticize the starch to improve its compatibility with polyester materials, and achieve the purpose of toughening. On the other hand, by controlling the average particle size of starch ≤ 1 μm, the probability of forming unevenness on the surface of the starch-based composite material can be reduced, thereby reducing the water contact angle of the starch-based composite material. As a result, the degree of infiltration of the starch dispersed phase in the starch-based composite material by air and moisture increases, and the plasticization effect is better, further improving the toughness of the material, enabling specific components to act synergistically through specific ratios, and obtaining a starch-based composite material with excellent toughness and good transparency at the same time.

[0012] In some of the embodiments, the components of the starch-based composite material satisfy at least one of the following conditions (1) to (2):

[0013] (1) Based on the total mass of the polyester material and the starch, the mass proportion of the polyester material is 50% - 80%;

[0014] (2) Based on the total mass of the polyester material and the starch, the mass proportion of the starch is 20% - 50%.

[0015] Further adjust the component ratio to further improve the mechanical properties of the starch-based composite material.

[0016] In some of the embodiments, the functionality T of the hydroxyl groups in the polyhydroxy compound satisfies: T ≥ 3;

[0017] Optionally, T satisfies: 3 ≤ T ≤ 7;

[0018] Optionally, the polyhydroxy compound includes at least one of polyols and their condensates;

[0019] Optionally, the polyhydroxy compound includes at least one of polyols and polyol ethers;

[0020] Optionally, the polyhydroxy compound includes at least one of glycerol, polyglycerol, sorbitol, and mannitol.

[0021] In some of these embodiments, the polyester material includes a biodegradable polyester;

[0022] Optionally, the monomers for preparing the biodegradable polyester include an acid monomer and an alcohol monomer. The acid monomer includes at least one of an aromatic polycarboxylic acid, a heteroaromatic polycarboxylic acid, an alicyclic polycarboxylic acid, an aliphatic polycarboxylic acid, and their ester derivatives. The alcohol monomer includes an aliphatic polyol;

[0023] Optionally, the aromatic polycarboxylic acid contains 6 to 20 carbon atoms;

[0024] Optionally, the heteroaromatic polycarboxylic acid contains 5 to 20 carbon atoms;

[0025] Optionally, the alicyclic polycarboxylic acid contains 3 to 30 carbon atoms;

[0026] Optionally, the aliphatic polycarboxylic acid contains 2 to 22 carbon atoms;

[0027] Optionally, the aliphatic polyol contains 2 to 22 carbon atoms.

[0028] In some of these embodiments, the acid monomer includes a first monomer and a second monomer. The first monomer includes at least one of an aromatic polycarboxylic acid and its ester derivatives. The second monomer includes an aliphatic polycarboxylic acid and its ester derivatives;

[0029] Optionally, based on the total molar amount of the acid monomer, the molar mass ratio of the first monomer is 30% to 70%;

[0030] Optionally, the first monomer includes an aromatic dicarboxylic acid, which can be at least one of terephthalic acid, phthalic acid, and furandicarboxylic acid;

[0031] Optionally, the second monomer includes an aliphatic dicarboxylic acid, which can be at least one of adipic acid, pimelic acid, suberic acid, sebacic acid, azelaic acid, undecanedioic acid, dodecanedioic acid, and tridecanedioic acid.

[0032] In some of these embodiments, the monomers for preparing the biodegradable polyester further include a hydroxy acid having 3 to 10 carbon atoms;

[0033] Optionally, the hydroxy acid includes lactic acid.

[0034] In some of these embodiments, the polyester material includes a copolymer of butylene adipate and butylene terephthalate and polylactic acid;

[0035] Optionally, in the proton nuclear magnetic resonance spectrum of the polyester material, the integrated area of the spectral peak with a chemical shift of 5.0 ppm to 5.3 ppm is X, and the integrated area of the spectral peak with a chemical shift of 8.1 ± 0.5 ppm is Y, where X and Y satisfy: 0.1 ≤ X / Y ≤ 0.3.

[0036] In some embodiments, the starch includes at least one of natural starch and its derivatives;

[0037] Optionally, the starch includes at least one of corn starch, potato starch, rice starch, cassava starch, and their esterified derivatives, etherified derivatives, and oxidized derivatives.

[0038] In some embodiments, the water contact angle of the starch-based composite material satisfies:

[0039] Let the starch-based composite material stand in an environment of 25°C ± 2°C and 50 RH% ± 5 RH% for 3 h. At this time, the water contact angle is θ1. Let the water droplet continue to stand on the surface of the starch-based composite material for 1 minute. At this time, the water contact angle is θ2, and H = θ1 - θ2, where H satisfies: H > 10°;

[0040] Optionally, θ2 < 90°.

[0041] In a second aspect of the present invention, there is provided a method for preparing a starch-based composite material, including the following steps:

[0042] Mix the components of the starch-based composite material in the first aspect and melt-extrude them.

[0043] In a third aspect of the present invention, there is provided the use of the starch-based composite material in the first aspect of the present invention or the starch-based composite material prepared by the method for preparing a starch-based composite material in the second aspect in the preparation of plastic products.

[0044] In a fourth aspect of the present invention, there is provided a plastic product, including the starch-based composite material in the first aspect of the present invention or the starch-based composite material prepared by the method for preparing a starch-based composite material in the second aspect. Description of the Drawings

[0045] To more clearly illustrate the technical solutions in the embodiments of the present application and to more fully understand the present application and its beneficial effects, the following will briefly introduce the accompanying drawings required for the description of the embodiments. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings. It should also be noted that the drawings are all drawn in a simplified form and are only used to conveniently and clearly assist in explaining the present invention. The various dimensions of each component shown in the drawings are arbitrarily shown, which may be accurate or may not be drawn to actual scale. For example, to make the illustration clearer, the dimensions of some components in the drawings are appropriately exaggerated. Unless otherwise specified, the components in the drawings are not drawn to scale. The present invention does not limit each dimension of each component.

[0046] Figure 1 Electron micrograph of the film product of the starch-based composite material prepared in Example 1;

[0047] Figure 2 Electron micrograph of the film product prepared in Comparative Example 1;

[0048] Figure 3 Photo of the initial contact angle θ1 on the surface of the film product of Example 1;

[0049] Figure 4 Photo of the stable contact angle θ2 on the surface of the film product of Example 1;

[0050] Figure 5 Photo of the initial contact angle θ1 on the surface of the film product of Comparative Example 1;

[0051] Figure 6 Photo of the stable contact angle θ2 on the surface of the film product of Comparative Example 1. Detailed implementation manners

[0052] The following will further elaborate on the present invention in conjunction with the accompanying drawings, implementation manners, and examples. It should be understood that these implementation manners and examples are only used to illustrate the present invention and not to limit the scope of the present invention. The purpose of providing these implementation manners and examples is to make the understanding of the disclosed content of the present invention more thorough and comprehensive. It should also be understood that the present invention can be implemented in many different forms and is not limited to the implementation manners and examples described herein. Those skilled in the art can make various modifications or alterations without departing from the essence of the present invention, and the equivalent forms obtained also fall within the protection scope of the present invention. For example, the features described or illustrated as part of one implementation manner can be combined in a suitable manner with another implementation manner to generate a new implementation manner. In addition, in the following description, a large number of specific details are given to provide a more thorough understanding of the present invention. It should be understood that the present invention can be implemented without one or more of these details.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the technical field to which this invention belongs. The terms used in the description of the present invention herein are for the purpose of describing embodiments and examples only and are not intended to limit the present invention.

[0054] Unless otherwise stated or there is a contradiction, the terms or phrases used herein have the following meanings:

[0055] In the present invention, "a plurality of", "a variety of", "multiple times", etc., unless otherwise specified, mean greater than 2 or equal to 2 in number. For example, "one or more" means one or greater than or equal to two.

[0056] As used herein, "combinations thereof", "any combination thereof", "any combination mode thereof", etc. include all suitable combination modes of any two or more of the listed items.

[0057] In this article, the "suitable combination mode", "suitable mode", "any suitable mode", etc. The "suitable" mentioned is subject to being able to implement the technical solution of the present invention, solve the technical problems of the present invention, and achieve the expected technical effects of the present invention.

[0058] In the present invention, "preferred", "better", "more preferable", "it is advisable" are only used to describe embodiments or examples with better effects. It should be understood that they do not constitute a limitation on the protection scope of the present invention. If there are multiple "preferred" in a technical solution, unless otherwise specified, and there is no contradiction or mutual restriction relationship, each "preferred" is independent of each other.

[0059] In the present invention, "further", "even further", "especially", etc. are used for descriptive purposes and indicate differences in content, but should not be construed as a limitation on the protection scope of the present invention.

[0060] In the present invention, "optionally", "optional", "optional" mean that it can be there or not, that is, it refers to any one of the two parallel options of "yes" or "no". If there are multiple "optional" in a technical solution, unless otherwise specified, and there is no contradiction or mutual restriction relationship, each "optional" is independent of each other.

[0061] In the present invention, in "the first aspect", "the second aspect", "the third aspect", "the fourth aspect", etc., the terms "first", "second", "third", "fourth", etc. are only for descriptive purposes, and cannot be construed as indicating or implying relative importance or quantity, nor can they be construed as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive listing and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0062] In the present invention, among the technical features described in an open-ended manner, there are included closed technical solutions composed of the listed features, as well as open technical solutions containing the listed features.

[0063] In the present invention, when it comes to numerical intervals (i.e., numerical ranges), unless otherwise specified, the distribution of the optional numerical values within this numerical interval is considered continuous, and it includes the two numerical endpoints of this numerical interval (i.e., the minimum value and the maximum value), as well as each numerical value between these two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers within this numerical interval, it includes the two endpoint integers of this numerical range, as well as each integer between the two endpoints, which is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be combined. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all sub-ranges subsumed therein. The "numerical value" in this numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. The "numerical interval" allows for a broad inclusion of numerical interval types such as percentage intervals, ratio intervals, ratio value intervals, etc.

[0064] For the temperature parameter in the present invention, unless otherwise specifically limited, it allows both constant temperature treatment and variation within a certain temperature range. It should be understood that the so-called constant temperature treatment allows the temperature to fluctuate within the accuracy range controlled by the instrument. It is allowed to fluctuate within a range such as ±5°C, ±4°C, ±3°C, ±2°C, ±1°C.

[0065] In the present invention, the term "room temperature" or "normal temperature" generally refers to 4°C to 35°C, for example, 20°C ± 5°C. In some embodiments of the present invention, "room temperature" or "normal temperature" refers to 10°C to 30°C. In some embodiments of the present invention, "room temperature" or "normal temperature" refers to 20°C to 30°C.

[0066] In the present invention, regarding the unit of the data range, if the unit is only attached after the right endpoint, it means that the units of the left endpoint and the right endpoint are the same. For example, 3 to 5 h means that the units of the left endpoint "3" and the right endpoint "5" are both h (hours).

[0067] All documents mentioned in the present invention are cited herein by reference as if each individual document was specifically cited. Unless it conflicts with the object and / or technical solution of the present application, the cited documents involved in the present invention are cited for all their contents and for all purposes. When the present invention involves cited documents, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When the present invention involves cited documents, the examples and preferred methods of the relevant technical features cited can also be incorporated into the present application for reference, but only to the extent that the present invention can be implemented. It should be understood that when the cited content conflicts with the description in the present application, the present application shall prevail or be amended adaptively according to the description in the present application.

[0068] In the description of the embodiments of the present invention, the mass or weight of the relevant components mentioned not only can refer to the specific content of each component, but also can represent the proportional relationship of the mass or weight between each component. Therefore, as long as the content of the relevant components in the description of the embodiments of the present invention is scaled up or down proportionally, it is within the scope disclosed in the description of the embodiments of the present invention. Specifically, the mass or weight described in the description of the embodiments of the present invention can be units well-known in the chemical industry such as μg, mg, g, kg, etc.

[0069] To address the technical problem of insufficient toughness of starch-based composites, the art often improves toughness by increasing the thickness of starch-based composite products or reducing the content of starch in starch-based composites, which greatly limits the application fields of starch-based composites.

[0070] Some technicians focus on the thermoplastic modification of starch, but the starch after thermoplastic modification still faces the problem of incompatibility with other resins, and further compatibilizers or other functional additives need to be added, resulting in limited effects and increased costs.

[0071] Based on this, the technicians of the present application break through the shackles of conventional technologies and blaze a new trail. They toughen by directly regulating the particle size of starch. The technicians of the present application found during the R & D process that when starch modifies polyester, starch acts as the dispersed phase, and the size of its particle size will cause differences in the air or moisture content in the convex gaps on the surface of the starch-based composite, resulting in changes in the water contact angle. The change in the water contact angle directly affects the wetting degree of moisture on the starch dispersed phase, and further affects the toughening effect.

[0072] Based on this, in the first aspect of the present invention, a starch-based composite is provided. The components of the starch-based composite include: a polyester material, starch, and a polyhydroxy compound;

[0073] Wherein, based on the total mass of the polyester material and the starch, the mass proportion of the polyester material is 15% - 85%, and the mass proportion of the starch is 15% - 85%;

[0074] The mass of the polyhydroxy compound is 10% - 50% of the mass of the starch;

[0075] The average particle size of the starch is ≤1 μm.

[0076] The above starch-based composite material has excellent toughness. Even in the state where the thickness is ≤16 μm, it can maintain excellent toughness: the elongation at break > 250%, among the 100% directional tensile strength, the transverse tensile strength > 5 MPa, and the longitudinal tensile strength > 10 MPa; at the same time, in the state where the thickness > 16 μm, it can maintain good transparency. When used to prepare plastic products, it can improve the service life of the products and is conducive to broadening its application range.

[0077] Although the mechanism is not yet clearly understood, the inventors of this application speculate that it is because: in the above starch-based composite material, on the one hand, a polyhydroxy compound is used to reduce the content of hydrogen bonds within and between starch molecules, increase the degree of freedom of starch molecular chains, plasticize the starch to improve its compatibility with the polyester material, and achieve the purpose of toughening; on the other hand, controlling the average particle size of the starch ≤1 μm can reduce the probability of forming unevenness on the surface of the starch-based composite material, thereby reducing the water contact angle of the starch-based composite material. As a result, the degree of infiltration of the starch dispersed phase in the starch-based composite material by air and moisture increases, the plasticization effect is better, the toughness of the material is further improved, and specific components act synergistically through specific ratios to obtain a starch-based composite material with excellent toughness and good transparency at the same time.

[0078] In some embodiments of the present invention, based on the total mass of the polyester material and the starch, the mass ratio of the polyester material is 50% - 80%.

[0079] In some embodiments of the present invention, based on the total mass of the polyester material and the starch, the mass ratio of the starch is 20% - 50%.

[0080] Further adjust the component ratio to further improve the mechanical properties of the starch-based composite material.

[0081] When the mass ratio of the above polyester material or starch is "15% - 85%", the mass ratio of the polyester material or starch takes values including the minimum and maximum values of this range, as well as each value between this minimum and maximum value. Specific examples include, but are not limited to, the point values in the examples and the following point values: 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%; or ranges composed of any two numerical values. For example, it can be 15% - 20%, 15% - 25%, 15% - 35%, 15% - 40%, 15% - 45%, 15% - 50%, 15% - 55%, 15% - 60%, 15% - 65%, 15% - 70%, 15% - 75%, 15% - 80%, 20% - 35%, 20% - 40%, 20% - 45%, 20% - 50%, 20% - 55%, 20% - 60%, 20% - 65%, 20% - 70%, 20% - 75%, 20% - 80%, 20% - 85%, 30% - 40%, 30% - 45%, 30% - 50%, 30% - 55%, 30% - 60%, 30% - 65%, 30% - 70%, 30% - 75%, 30% - 80%, 3% - 85%, 40% - 50%, 40% - 55%, 40% - 60%, 40% - 65%, 40% - 70%, 40% - 75%, 40% - 80%, 40% - 85%, 50% - 65%, 50% - 70%, 50% - 75%, 50% - 80%, 50% - 85%, 60% - 75%, 60% - 80%, 60% - 85%.

[0082] For the above range "10% - 50%", the values include the minimum and maximum values of this range, as well as each value between this minimum and maximum value. Specific examples include, but are not limited to, the point values in the examples and the following point values: 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%; or ranges composed of any two numerical values. For example, it can be 15% - 20%, 15% - 25%, 15% - 35%, 15% - 40%, 15% - 45%, 15% - 50%, 20% - 35%, 20% - 40%, 20% - 45%, 20% - 50%, 30% - 40%, 30% - 45%, 30% - 50%.

[0083] It is understood that the average particle size of the starch is greater than 0 and ≤ 1 μm.

[0084] In some embodiments of the present invention, the functionality T of the hydroxyl group in the polyhydroxy compound satisfies: T ≥ 3.

[0085] The speculation on using polyhydroxy compounds to reduce the content of hydrogen bonds within and between starch molecules is as follows: The hydroxyl groups in polyhydroxy compounds can form hydrogen bonds with the hydroxyl groups in starch molecules, thereby replacing and reducing the hydrogen bonds within and between starch molecules and preventing their self-aggregation due to the formation of hydrogen bonds within and between molecules.

[0086] Optionally, T satisfies: 3 ≤ T ≤ 7.

[0087] Optionally, the polyhydroxy compound includes at least one of polyols and their condensates.

[0088] The polyol condensate can be a polyol ether formed by dehydration condensation of polyols.

[0089] Optionally, the polyhydroxy compound includes at least one of polyols and polyol ethers.

[0090] Optionally, the polyhydroxy compound includes at least one of glycerol, polyglycerol, sorbitol, and mannitol.

[0091] In some embodiments, the polyester material includes biodegradable polyester.

[0092] The biodegradable polyester has biodegradable properties and can further improve the biodegradability of the starch-based composite material.

[0093] Optionally, the monomers for preparing the biodegradable polyester include acid monomers and alcohol monomers. The acid monomers include at least one of aromatic polyacids, heteroaromatic polyacids, alicyclic polyacids, aliphatic polyacids, and their ester derivatives, and the alcohol monomers include aliphatic polyols.

[0094] It is understandable that the polyacids in the acid monomers can undergo esterification condensation with the alcohol monomers to form polyesters, and the ester derivatives of the polyacids in the acid monomers can undergo transesterification condensation with the alcohol monomers to form polyesters.

[0095] Optionally, the aromatic polyacid contains 6 to 20 carbon atoms.

[0096] Optionally, the aromatic polyacid contains 6 to 10 carbon atoms.

[0097] Optionally, the heteroaromatic polyacid contains 5 to 20 carbon atoms.

[0098] Optionally, the heteroaromatic polyacid contains 6 to 10 carbon atoms.

[0099] Optionally, the heteroatoms contained in the heteroaromatic group of the heteroaromatic polyacid include, but are not limited to: nitrogen, sulfur.

[0100] Optionally, the alicyclic polyacid contains 3 to 30 carbon atoms.

[0101] Optionally, the alicyclic polybasic acid contains 6 to 10 carbon atoms.

[0102] Optionally, the aliphatic polybasic acid contains 2 to 22 carbon atoms.

[0103] Optionally, the aliphatic polybasic acid contains 2 to 10 carbon atoms.

[0104] Optionally, the aliphatic polyhydric alcohol contains 2 to 22 carbon atoms.

[0105] Optionally, the aliphatic polyhydric alcohol contains 2 to 10 carbon atoms.

[0106] It should be noted that in the above "polybasic acid", the functionality of the carboxyl group is ≥2, that is, dibasic acids and compounds containing more than 2 carboxyl groups; in the above "polyhydric alcohol", the functionality of the hydroxyl group is ≥2, that is, dihydric alcohols and compounds containing more than 2 hydroxyl groups.

[0107] Optionally, the above acid monomer includes at least one of aromatic dibasic acids, heteroaromatic dibasic acids, alicyclic dibasic acids, aliphatic dibasic acids and their ester derivatives.

[0108] Optionally, the acid monomer includes a first monomer and a second monomer. The first monomer includes at least one of aromatic polybasic acids and their ester derivatives, and the second monomer includes aromatic polybasic acids and their ester derivatives.

[0109] In this way, introducing aromatic segments and aromatic segments into the polyester material at the same time is beneficial to improving the toughness of the starch-based composite material.

[0110] Optionally, based on the total molar amount of the acid monomer, the molar mass ratio of the first monomer is 30% to 70%.

[0111] Optionally, based on the total molar amount of the acid monomer, the molar mass ratio of the first monomer is 30% to 50%.

[0112] Optionally, the first monomer includes aromatic dibasic acids; further optionally at least one of terephthalic acid, phthalic acid and furandicarboxylic acid.

[0113] Optionally, the second monomer includes aliphatic dibasic acids; further optionally at least one of adipic acid, pimelic acid, suberic acid, sebacic acid, azelaic acid, undecanedioic acid, dodecanedioic acid, tridecanedioic acid.

[0114] In some of these embodiments, the preparation monomers of the above biodegradable polyester further include hydroxy acids having 3 to 10 carbon atoms.

[0115] Optionally, the hydroxy acid includes at least one of lactic acid and hydroxyalkanoic acid.

[0116] It should be noted that hydroxyalkanoic acid refers to the monomer of polyhydroxyalkanoate (PHA).

[0117] Optionally, the hydroxy acid includes lactic acid.

[0118] In some embodiments of the present invention, the polyester material includes a copolymer of butylene adipate and butylene terephthalate and polylactic acid.

[0119] In some of these embodiments, the weight-average molecular weight of the polylactic acid is 40,000 to 200,000.

[0120] In some embodiments of the present invention, the polyester material is a copolymer of butylene adipate and butylene terephthalate.

[0121] Optionally, the copolymer of butylene adipate and butylene terephthalate is poly(butylene adipate-co-terephthalate) (PBAT).

[0122] Optionally, in the nuclear magnetic resonance hydrogen spectrum of the polyester material, the integrated area of the peak with a chemical shift of 5.0 ppm to 5.3 ppm is X, and the integrated area of the peak with a chemical shift of 8.1 ± 0.5 ppm is Y, and X and Y satisfy: 0.1 ≤ X / Y ≤ 0.3.

[0123] X represents the integral of the proton signal peak of the methylene group contained in lactic acid, which is the monomer of polylactic acid (PLA), and Y represents the integral of the proton signal peak on the benzene ring in poly(butylene adipate-co-terephthalate) (PBAT). The mass ratio of PLA to PBAT in the polyester material can be analyzed and calculated through the ratio of X / Y.

[0124] In some embodiments of the present invention, the starch includes at least one of natural starch and its derivatives.

[0125] Optionally, the starch includes at least one of corn starch, potato starch, rice starch, tapioca starch and their esterified derivatives, etherified derivatives and oxidized derivatives.

[0126] In some embodiments of the present invention, the water contact angle of the starch-based composite material at 25°C ± 2°C satisfies: The starch-based composite material is allowed to stand in an environment of 25°C ± 2°C and 50 RH% ± 5 RH% for 3 h, and at this time the water contact angle is θ1. Then continue to stand for 1 minute, and at this time the water contact angle is θ2. H = θ1 - θ2, and H satisfies: H > 10°.

[0127] In some of these embodiments, when testing H of the test sample, 3 samples are taken and the above test steps are carried out respectively to obtain three values of H, and then the average value is taken.

[0128] Optionally, θ2 < 90°.

[0129] It is understandable that RH% represents relative humidity, which refers to the percentage of the partial pressure of actual water vapor in a unit volume of air to the saturated water vapor pressure at the same temperature and volume.

[0130] Optionally, 10° < H ≤ 30°

[0131] Optionally, 0 ≤ θ2 < 90°.

[0132] In some embodiments, the weight average molecular weight of the polyester material is 40,000 - 250,000. In the second aspect of the present invention, a method for preparing a starch-based composite material is provided, which includes the following step S10.

[0133] S10: Mix the components of the starch-based composite material in the first aspect and melt and extrude them.

[0134] In some embodiments of the present invention, melt extrusion is carried out using an extruder. Further, the extruder can be a twin-screw extruder. Further still, the length-diameter ratio of the screw of the twin-screw extruder can be (40 - 48):1, and the length-diameter ratio of the screw can also be selected from any one of the following ratios or an interval formed by any two of the ratios: 40:1, 41:1, 42:1, 43:1, 44:1, 45:1, 46:1, 47:1, 48:1, etc.

[0135] In some embodiments of the present invention, when melt extrusion is carried out using an extruder (such as a twin-screw extruder), the screw speed can be 300 - 600 r / min; further, in the direction of the material advancement, the barrel is provided with nine temperature zones: Zone 1: 80°C, Zone 2: 100°C, Zone 3: 120°C, Zone 4: 160°C, Zone 5: 170°C, Zone 6: 170°C, Zone 7: 170°C, Zone 8: 170°C, Zone 9: 170°C; further, the head: 175°C.

[0136] Optionally, the screw speed can also be selected from any one of the following speeds or an interval formed by any two of the speeds: 300 r / min, 350 r / min, 400 r / min, 450 r / min, 500 r / min, 550 r / min, 600 r / min, etc.

[0137] Optionally, the extrusion speed is 400 kg / h - 600 kg / h.

[0138] In the third aspect of the present invention, there is provided the use of the starch-based composite material in the first aspect of the present invention or the starch-based composite material prepared by the preparation method in the second aspect of the present invention in the preparation of plastic products.

[0139] In the fourth aspect of the present invention, there is provided a plastic product, comprising a starch-based composite material prepared by the starch-based composite material of the first aspect or the preparation method of the starch-based composite material of the second aspect.

[0140] The above-mentioned starch-based composite material has excellent toughness. Even in a state with a thickness < 16 μm, it can maintain excellent toughness: the elongation at break > 250%, among the 100% oriented tensile strength, the transverse tensile strength > 5 MPa, and the longitudinal tensile strength > 10 MPa. When used to prepare plastic products, it can improve the service life of the products and is beneficial to broaden its application scope.

[0141] The embodiments of the present invention will be described in detail below in conjunction with the examples. It should be understood that these examples are only used to illustrate the present invention and not to limit the scope of the present invention. For the experimental methods without specific conditions in the following examples, the guidance given in the present invention is preferably referred to, and it can also be in accordance with the experimental manuals or conventional conditions in the art, or in accordance with the conditions recommended by the manufacturer, or referring to the experimental methods known in the art.

[0142] In the following specific examples, for the measurement parameters of the raw material components, if there is no special description, there may be slight deviations within the weighing accuracy range. For the temperature and time parameters, acceptable deviations caused by instrument test accuracy or operation accuracy are allowed. Specific Examples

[0143] Some specific examples are provided below.

[0144] 1. Raw Materials

[0145] In the following examples, unless otherwise stated, the sources of each raw material are as follows:

[0146] Polyester material A: Polybutylene adipate / terephthalate (PBAT), ECOPOND® A400 from Zhuhai Jinfagroup Biomaterials Co., Ltd., with a weight average molecular weight of 120,000;

[0147] Polyester material B: Polylactic acid: (Ingeo™ 4060D from NatureWorks, USA), with a weight average molecular weight of 110,000.

[0148] Mix polyester material A and polyester material B to obtain the mixed polyester material, and perform nuclear magnetic resonance hydrogen spectrum test on the mixed polyester material. The integral area of the spectral peak with a chemical shift of 5.0 ppm to 5.3 ppm is X, and the integral area of the spectral peak with a chemical shift of 8.1 ± 0.5 ppm is Y. The specific ratio of X / Y is shown in Table 1.

[0149] Starch: Edible corn starch from Shandong Shouguang Jueneng Jinma Development Co., Ltd., and starches with different particle sizes are screened out using molecular sieve sieves or other particle size screening devices.

[0150] Polyhydroxy compounds: Glycerol, sorbitol, and mannitol, commercially available.

[0151] 2. Preparation method

[0152] Unless otherwise specified, the following equipment is used:

[0153] The starch-based composites and plastic products in the following examples and comparative examples are prepared by the following method:

[0154] S1: Weigh each component according to the raw material ratio shown in Table 1 and premix to obtain a premix. Among them, the average particle size of the starch is 0.6 μm.

[0155] S2: Put the premix prepared in step S1 into a twin-screw extruder for melt blending and pelletizing. The length-diameter ratio of the screw is 40:1, and its set temperature is: Zone 1: 80 °C, Zone 2: 100 °C, Zone 3: 120 °C, Zone 4: 160 °C, Zone 5: 170 °C, Zone 6: 170 °C, Zone 7: 170 °C, Zone 8: 170 °C, Zone 9: 170 °C, Head: 175 °C, Screw speed: 300 rpm, Extrusion speed: 500 kg / h, to obtain a starch-based composite.

[0156] S3: Prepare a batch of film products with a thickness of 15 ± 1 µm from the starch-based composite on a single-screw blown film machine with a screw diameter of 45 cm and a length-diameter ratio of 20:1, and test the average apparent thickness D1 according to the ISO 4593:1993 standard. The specific thickness is shown in Table 1.

[0157] Using the same batch of starch-based composites, prepare a batch of film products with a thickness > 16 µm from the starch-based composite on a single-screw blown film machine, and test the average apparent thickness D2 according to the ISO 4593:1993 standard. The specific thickness is shown in Table 1.

[0158] S4: Testing

[0159] 1. After etching the surface of the film product with a thickness of 15 ± 1 µm using 5M hydrochloric acid and then sputtering with gold, observe using a scanning electron microscope (SEM, JSM-6330F, Tokyo, Japan) at a voltage of 15 kV. The electron micrograph of the film product with a thickness of 15 ± 1 µm prepared in Example 1 is as Figure 1 shown.

[0160] The size and distribution of holes in the thin film products were analyzed by image analysis software (Image Pro plus 6). Data within a range of 100×100 µm were measured for each sample, and the average particle size was calculated by testing 10 samples and denoted as R, which is the average particle size of starch in the thin film.

[0161] 2. Cut the thin film products with a thickness of 15 ± 1 µm into square film pieces of 1 cm × 1 cm in size, place them in an environment of 25 ± 2 °C and 50 ± 5 RH% for 3 hours to stabilize, then measure the initial contact angle θ1 of the sample surface with a surface contact angle measuring instrument (KRUSS DSA10-MK), and then measure the contact angle θ2 of the sample surface again after standing for 1 minute. H = θ1 - θ2, and the average value of H is calculated by measuring 3 samples.

[0162] Among them, a photo of the initial contact angle θ1 of the surface of the thin film product in Example 1 is as Figure 3 shown, and a photo of the stable contact angle θ2 is as Figure 4 shown. It can be clearly seen that the wetting area of water on the surface of the thin film product becomes larger, that is, the contact angle becomes smaller.

[0163] 3. Test the 100% oriented tensile strength and elongation at break of the thin film products with a thickness of 15 ± 1 µm according to the standard of ISO 527-3, where MD = longitudinal direction and TD = transverse direction.

[0164] The raw material formulas and experimental results of Examples 1-10 and Comparative Examples 1-5 can be seen in Table 1. Among them, molecular sieves can be used to screen out corn starch with different particle sizes. The particle sizes of the corn starch used in Examples 1-10 and Comparative Examples 1-5 are 0.6 µm, 0.8 µm, 0.7 µm, 0.6 µm, 0.8 µm, 0.9 µm, 0.8 µm, 0.9 µm, 0.7 µm, 0.6 µm, 1.5 µm, 0.7 µm, 0.9 µm, 0.9 µm, and 2.9 µm respectively.

[0165] Among them, a photo of the initial contact angle θ1 of the surface of the thin film product in Comparative Example 1 is as Figure 5 shown, and a photo of the stable contact angle θ2 is as Figure 6 shown.

[0166] Among them, the mass percentages of the polyester material and starch are calculated based on the total mass of the polyester material and starch, and the mass percentage of the polyhydroxy compound is calculated based on the mass of the starch.

[0167] Table 1

[0168]

[0169] Note: " / " represents the absence of this substance.

[0170] Furthermore, the materials prepared in the above-mentioned examples and comparative examples were made into film products with a thickness of 18 ± 1 µm on a single-screw blown film machine with a screw diameter of 45 cm and a length-to-diameter ratio of 20:1, and their transparency was tested. The light transmittance and haze were tested with reference to GB / T 2410-200. The higher the light transmittance and the lower the haze, the better the transparency. For the specific results, please refer to Table 2.

[0171] Table 2

[0172]

[0173] It can be seen from the data analysis in Tables 1 and 2 that the starch-based composite material of the present application has excellent toughness. Even in the state where the thickness ≤ 16 µm, it can still maintain excellent toughness. When used to prepare plastic products, it can improve the service life of the products. In the state where the thickness ≥ 16 µm, it can still maintain good transparency, which is beneficial to broadening its application range.

[0174] The technical features of the above embodiments and examples can be combined in any suitable manner. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments and examples are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope described in this specification.

[0175] The above embodiments only represent several implementation manners of the present invention, which are convenient for understanding the technical solutions of the present invention specifically and in detail. However, it should not be construed as a limitation on the protection scope of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. In addition, it should be understood that after reading the above teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and the equivalent forms obtained also fall within the protection scope of the present invention. It should also be understood that the technical solutions obtained by those skilled in the art through logical analysis, reasoning or limited experiments based on the technical solutions provided by the present invention are all within the protection scope of the appended claims of the present invention. Therefore, the protection scope of the present invention patent should be determined by the content of the appended claims, and the description and drawings can be used to explain the content of the claims.

Claims

1. A starch-based composite material, characterized in that, The components of the starch-based composite material include: a polyester material, starch, and a polyhydroxy compound; Among them, based on the total mass of the polyester material and the starch, the mass proportion of the polyester material is 15% - 85%, and the mass proportion of the starch is 15% - 85%; The mass of the polyhydroxy compound is 10% - 50% of the mass of the starch; The average particle size of the starch ≤ 1 μm; the polyester material includes a copolymer of butylene adipate and butylene terephthalate and polylactic acid; based on the total molar number of acid monomers in the copolymer of butylene adipate and butylene terephthalate, the molar proportion of terephthalic acid is 30% - 70%; In the nuclear magnetic resonance hydrogen spectrum of the polyester material, the integral area of the peak with a chemical shift of 5.0 ppm - 5.3 ppm is X, and the integral area of the peak with a chemical shift of 8.1 ± 0.5 ppm is Y, and X and Y satisfy: 0.1 ≤ X / Y ≤ 0.

3.

2. The starch-based composite material according to claim 1, wherein The water contact angle of the starch-based composite material satisfies: the starch-based composite material is left standing in an environment of 25°C ± 2°C and 50 RH% ± 5RH% for 3 h, and at this time the water contact angle is θ1. Then, the water droplet is left standing on the surface of the starch-based composite material for another 1 minute, and at this time the water contact angle is θ2, and H = θ1 - θ2, and H satisfies: H ≥ 14°.

3. The starch-based composite material according to claim 1, wherein The components of the starch-based composite material satisfy at least one of the following conditions (1) - (2): (1) Based on the total mass of the polyester material and the starch, the mass proportion of the polyester material is 50% - 80%; (2) Based on the total mass of the polyester material and the starch, the mass proportion of the starch is 20% - 50%.

4. The starch-based composite material according to any one of claims 1 to 3, characterized in that, The functionality T of the hydroxyl groups in the polyhydroxy compound satisfies: T ≥ 3.

5. The starch-based composite material according to claim 4, characterized in that T satisfies: 3 ≤ T ≤ 7.

6. The starch-based composite material according to claim 5, wherein The polyhydroxy compound includes at least one of a polyol and a polyol ether.

7. The starch-based composite material according to claim 4, wherein The polyhydroxy compound includes at least one of glycerol, polyglycerol, sorbitol, and mannitol.

8. The starch-based composite material according to any one of claims 1 to 3, characterized in that, The starch includes at least one of natural starch and its derivatives.

9. The starch-based composite material according to claim 8, wherein The starch includes at least one of corn starch, potato starch, rice starch, cassava starch, and their esterified derivatives, etherified derivatives, and oxidized derivatives.

10. The starch-based composite material according to claim 2, characterized in that, θ2 < 90°.

11. A method for preparing a starch-based composite material, characterized in that, It includes the following steps: Mix the components of the starch-based composite material according to any one of claims 1 - 10, and perform melt extrusion.

12. The application of the starch-based composite material prepared by the preparation method of the starch-based composite material according to any one of claims 1 - 10 or claim 11 in the preparation of plastic products.

13. A plastic product, characterized in that, It includes the starch-based composite material according to any one of claims 1 - 10 or the starch-based composite material prepared by the preparation method of the starch-based composite material according to claim 11.

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