Starch-based composite material, preparation method therefor and use thereof, and plastic product

Abstract

The present application relates to a starch-based composite material, a preparation method therefor and the use thereof, and a plastic product. Components of the starch-based composite material comprise: a polyester material, starch and a polyhydroxy compound, wherein on the basis of the total mass of the polyester material and the starch, the mass percentage of the polyester material is 15%-85%, and the mass percentage of the starch is 15%-85%; the mass of the polyhydroxy compound is 10%-50% of the mass of the starch; and the average particle size of the starch is less than or equal to 1μm.

Description

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

[0001] Related applications

[0002] This application claims priority to Chinese patent application number 202311727101.4, filed on December 14, 2023, entitled “Starch-based composite materials, preparation methods and applications thereof, and plastic products,” the entire text of which is hereby incorporated by reference. Technical Field

[0003] The present application relates to the technical field of composite materials, and in particular to a starch-based composite material, a preparation method and application thereof, and a plastic product. Background Art

[0004] With the awakening of environmental awareness, researchers are increasingly interested in developing "green polymers" to replace conventional petrochemical plastics. Technicians often use biodegradable biomaterials to modify resins to create biodegradable materials. Starch, among other materials, is diverse, abundant, and inexpensive. It is also susceptible to microbial attack and provides nutrients for microorganisms. The final products of biodegradation are carbon dioxide and water, which pose no environmental risks. Therefore, starch is often used in the preparation of biodegradable materials, providing a promising approach to addressing white pollution.

[0005] However, since starch is a polyhydroxyl natural macromolecular compound, its molecules and adjacent molecules mostly interact through hydrogen bonds to form a microcrystalline structure. During the traditional blending process, this structure is not easy to change and lacks plasticity, resulting in poor compatibility with the base material. When used to modify resins to prepare biodegradable materials, it often has an adverse effect on the toughness and other mechanical properties of the resin, especially in the film state. Its toughness cannot meet the requirements of the relevant application fields, thereby limiting its application range.

[0006] Therefore, traditional technologies still need to be improved.

[0007] Summary of the Invention

[0008] Based on this, the present application provides a starch-based composite material with excellent toughness, a preparation method and application thereof, and a plastic product.

[0009] In a first aspect of the present application, a starch-based composite material is provided, wherein the components of the starch-based composite material include: a polyester material, starch and a polyhydroxy compound;

[0010] Wherein, based on the total mass of the polyester material and the starch, the mass proportion of the polyester material is 15% to 85%, and the mass proportion of the starch is 15% to 85%;

[0011] The mass of the polyhydroxy compound is 10% to 50% of the mass of the starch;

[0012] The average particle size of the starch is ≤1 μm.

[0013] The above-mentioned starch-based composite material has excellent toughness and can maintain excellent toughness even when the thickness is <16μm: the elongation at break is >250%, the 100% directional tensile strength, the transverse tensile strength is >5MPa, and the longitudinal tensile strength is >10MPa; at the same time, when the thickness is ≥16μm, it can maintain good transparency. When used to prepare plastic products, it can increase the service life of the products and help broaden their application range.

[0014] Although the mechanism is not yet clear, the inventors of this application speculate that it is because: in the above-mentioned 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 the starch molecular chain, and plasticize the starch to improve its compatibility with the polyester material, thereby achieving the purpose of toughening; on the other hand, regulating the average particle size of the starch to ≤1μm can reduce the probability of forming concave and convex shapes on the surface of the starch-based composite material, thereby reducing the water contact angle of the starch-based composite material, thereby increasing the degree to which the starch dispersed phase in the starch-based composite material is infiltrated by air and water, and having a better plasticizing effect, further improving the toughness of the material, and making specific components work synergistically through specific ratios to obtain a starch-based composite material with excellent toughness and at the same time maintaining good transparency.

[0015] In some embodiments, the components of the starch-based composite material meet at least one of the following conditions (1) to (2):

[0016] (1) Based on the total mass of the polyester material and the starch, the mass proportion of the polyester material is 50% to 80%;

[0017] (2) Based on the total mass of the polyester material and the starch, the mass proportion of the starch is 20% to 50%.

[0018] The component ratio can be further adjusted to further improve the mechanical properties of starch-based composite materials.

[0019] In some embodiments, the functionality T of the hydroxyl group in the polyhydroxy compound satisfies: T ≥ 3;

[0020] Optionally, T satisfies: 3≤T≤7;

[0021] Optionally, the polyhydroxy compound includes at least one of a polyol and a condensate thereof;

[0022] Optionally, the polyhydroxy compound includes at least one of a polyol and a polyol ether;

[0023] Optionally, the polyhydroxy compound includes at least one of glycerol, polyglycerol, sorbitol and mannitol.

[0024] In some embodiments, the polyester material comprises biodegradable polyester;

[0025] 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 ester derivatives thereof, and the alcohol monomers include aliphatic polyols;

[0026] Optionally, the aromatic polyacid contains 6 to 20 carbon atoms;

[0027] Optionally, the heteroaromatic polyacid contains 5 to 20 carbon atoms;

[0028] Optionally, the alicyclic polybasic acid contains 3 to 30 carbon atoms;

[0029] Optionally, the aliphatic polyacid contains 2 to 22 carbon atoms;

[0030] Optionally, the aliphatic polyol contains 2 to 22 carbon atoms.

[0031] In some embodiments, the acid monomer includes a first monomer and a second monomer, the first monomer includes at least one of an aromatic polyacid and an ester derivative thereof, and the second monomer includes an aliphatic polyacid and an ester derivative thereof;

[0032] Optionally, based on the total molar number of the acid monomers, the molar mass of the first monomer accounts for 30% to 70%;

[0033] Optionally, the first monomer comprises an aromatic dibasic acid, which may be at least one of terephthalic acid, phthalic acid and furandicarboxylic acid;

[0034] Optionally, the second monomer includes an aliphatic dibasic 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.

[0035] In some embodiments, the monomers for preparing the biodegradable polyester further include a hydroxy acid having 3 to 10 carbon atoms;

[0036] Optionally, the hydroxy acid comprises lactic acid.

[0037] In some embodiments, the polyester material includes a copolymer of butylene adipate and butylene terephthalate and polylactic acid;

[0038] Optionally, in the hydrogen nuclear magnetic resonance spectrum of the polyester material, the integrated area of ​​the peak with a chemical shift of 5.0ppm to 5.3ppm is X, the integrated area of ​​the peak with a chemical shift of 8.1±0.5ppm is Y, and X and Y satisfy: 0.1≤X / Y≤0.3.

[0039] In some embodiments, the starch comprises at least one of natural starch and its derivatives;

[0040] Optionally, the starch includes at least one of corn starch, potato starch, rice starch, tapioca starch, and esterified derivatives, etherified derivatives, and oxidized derivatives thereof.

[0041] In some embodiments, the water contact angle of the starch-based composite material satisfies:

[0042] The starch-based composite material is allowed to stand for 3 hours in an environment of 25°C ± 2°C and 50 RH% ± 5 RH%, at which time the water contact angle is θ1. A water droplet is allowed to stand on the surface of the starch-based composite material for another 1 minute, at which time the water contact angle is θ2, where H = θ1 - θ2, and H satisfies: H > 10°;

[0043] Optionally, θ2<90°.

[0044] In a second aspect of the present application, a method for preparing a starch-based composite material is provided, comprising the following steps:

[0045] The components of the starch-based composite material of the first aspect are mixed and melt-extruded.

[0046] In a third aspect of the present application, there is provided use of a starch-based composite material prepared by the preparation method of the starch-based composite material of the first aspect or the second aspect of the present application in the preparation of plastic products.

[0047] In a fourth aspect of the present application, a plastic product is provided, comprising the starch-based composite material of the first aspect or the starch-based composite material prepared by the preparation method of the starch-based composite material of the second aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the conventional technology, the following briefly introduces the drawings required for use in the embodiments or the conventional technology descriptions. Obviously, the drawings described below are merely embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the disclosed drawings without any creative work.

[0049] It should also be noted that the drawings are simplified and are intended solely to facilitate and clarify the description of this application. The dimensions of each component shown in the drawings are arbitrary and may be accurate or not drawn to scale. For example, to enhance clarity, the dimensions of components are exaggerated in some places in the drawings. Unless otherwise specified, the components in the drawings are not drawn to scale. This application does not limit the dimensions of each component.

[0050] FIG1 is an electron microscope image of a film product of a starch-based composite material obtained in Example 1;

[0051] FIG2 is an electron microscope image of the thin film product obtained in Comparative Example 1;

[0052] FIG3 is a photograph of the initial contact angle θ1 of the film product surface in Example 1;

[0053] FIG4 is a photograph of the stable contact angle θ2 on the surface of the film product of Example 1;

[0054] FIG5 is a photograph of the initial contact angle θ1 on the surface of the film product of Comparative Example 1;

[0055] FIG6 is a photograph of the stable contact angle θ2 on the surface of the film product of Comparative Example 1. DETAILED DESCRIPTION

[0056] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0057] For example, features illustrated or described as part of one embodiment may be combined in another embodiment in a suitable manner to produce a new embodiment. In addition, in the description below, a large number of specific details are given in order to provide a more complete understanding of the present application, and it should be understood that the present application can be implemented without one or more of these details.

[0058] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application pertains. The terms used herein in the specification of this application are for the purpose of describing embodiments and examples only and are not intended to limit this application.

[0059] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0060] In this application, "plurality", "multiple", "multiple times", etc., unless otherwise specified, refer to a quantity greater than or equal to 2. For example, "one or more" means one or more than or equal to two.

[0061] As used herein, "combination thereof", "any combination thereof", "any combination thereof" and the like include all suitable combinations of any two or more of the listed items.

[0062] Herein, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc. shall be based on the ability to implement the technical solution of this application, solve the technical problems of this application, and achieve the expected technical effects of this application.

[0063] Herein, the terms "preferred," "better," "more preferred," and "suitable" are used solely to describe preferred implementations or examples and should not be construed as limiting the scope of protection of this application. If multiple "preferred" terms appear in a technical solution, each "preferred" term is considered independent unless otherwise specified and there are no contradictions or mutual constraints.

[0064] In this application, "further", "further", "particularly" and the like are used for descriptive purposes to indicate differences in content, but should not be understood as limiting the scope of protection of this application.

[0065] In this application, the terms "optionally," "optional," and "optional" mean optional or dispensable, i.e., they refer to either option being selected from two parallel options: "with" or "without." If a technical solution contains multiple "optional" clauses, each "optional" clause is independent unless otherwise specified and there are no contradictions or constraints.

[0066] In this application, the terms "first," "second," "third," "fourth," etc. in "the first aspect," "the second aspect," "the third aspect," "the fourth aspect," etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or quantity, nor should they be understood as implicitly indicating the importance or quantity of the indicated technical features. Furthermore, "first," "second," "third," "fourth," etc. serve only as non-exhaustive enumeration and description, and should be understood not to constitute a closed-ended limitation on quantity.

[0067] In this application, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0068] In this application, when referring to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous and includes the two numerical endpoints (i.e., the minimum and maximum values) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when a numerical interval only refers to an integer in the numerical interval, including the two endpoint integers of the numerical range and each integer between the two endpoints, is equivalent to directly enumerating each integer. When multiple numerical ranges are provided to describe a feature or characteristic, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical range disclosed herein should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows broadly including numerical interval types such as percentage intervals, ratio intervals, and ratio intervals.

[0069] Unless otherwise specified, the temperature parameters in this application allow for both constant temperature treatment and temperature fluctuations within a certain temperature range. It should be understood that the constant temperature treatment allows for temperature fluctuations within the accuracy range of instrument control. Fluctuations within ranges such as ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are permitted.

[0070] In this application, 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 this application, "room temperature" or "normal temperature" refers to 10°C to 30°C. In some embodiments of this application, "room temperature" or "normal temperature" refers to 20°C to 30°C.

[0071] In this application, when referring to a data range, if the unit is only after the right endpoint, it means that the units of the left and right endpoints are the same. For example, 3~5h means that the units of the left endpoint "3" and the right endpoint "5" are both h (hours).

[0072] All documents mentioned in this application are cited as references in this application, just as each document is cited as a reference individually. Unless they conflict with the invention purpose and / or technical solution of this application, the cited documents involved in this application are cited in their entirety and for all purposes. When cited documents are involved in this application, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When cited documents are involved in this application, the examples and preferred embodiments of the cited relevant technical features may also be incorporated into this application as references, but are limited to the ability to implement this application. It should be understood that when the cited content conflicts with the description in this application, the present application shall prevail or be adaptively amended according to the description in this application.

[0073] The mass or weight of the relevant components mentioned in the examples of this application may not only refer to the specific content of each component, but also represent the proportional relationship of the mass or weight of each component. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the examples of this application, it is within the scope disclosed in the examples of this application. Specifically, the mass or weight described in the examples of this application may be units known in the chemical industry such as μg, mg, g, and kg.

[0074] To address the technical issue of insufficient toughness of starch-based composite materials, the art often increases the toughness by increasing the thickness of starch-based composite products or reducing the starch content in the starch-based composite materials, which greatly limits the application areas of starch-based composite materials.

[0075] Some technicians focus on thermoplastic modification of starch, but the thermoplastic modified starch still faces the problem of mismatch in compatibility with other resins, and requires further addition of compatibilizers or other functional additives, which has limited effects and increases costs.

[0076] Based on this, the technical personnel of this application broke the constraints of conventional technology and took a different approach by directly regulating the particle size of starch to increase toughness. During the research and development process, the technical personnel of this application discovered that when starch modifies polyester, starch is used as the dispersed phase, and the size of its particle size will lead to differences in the amount of air or moisture in the gaps between the protrusions on the surface of the starch-based composite material, causing changes in the water contact angle. The change in the water contact angle directly affects the degree of water infiltration into the starch dispersed phase, thereby affecting the toughening effect.

[0077] Based on this, in a first aspect of the present application, a starch-based composite material is provided, wherein the components of the starch-based composite material include: a polyester material, starch and a polyhydroxy compound;

[0078] Wherein, based on the total mass of the polyester material and the starch, the mass proportion of the polyester material is 15% to 85%, and the mass proportion of the starch is 15% to 85%;

[0079] The mass of the polyhydroxy compound is 10% to 50% of the mass of the starch;

[0080] The average particle size of the starch is ≤1 μm.

[0081] The starch-based composite material has excellent toughness and can maintain excellent toughness even when the thickness is ≤16μm: the elongation at break is >250%, the transverse tensile strength is >5MPa, and the longitudinal tensile strength is >10MPa in 100% directional tensile strength; at the same time, it can maintain good transparency when the thickness is >16μm. When used in the preparation of plastic products, it can increase the service life of the products and help broaden their application range.

[0082] Although the mechanism is not yet clear, the inventors of this application speculate that it is because: in the above-mentioned 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 the starch molecular chain, and plasticize the starch to improve its compatibility with the polyester material, thereby achieving the purpose of toughening; on the other hand, regulating the average particle size of the starch to ≤1μm can reduce the probability of forming concave and convex shapes on the surface of the starch-based composite material, thereby reducing the water contact angle of the starch-based composite material, thereby increasing the degree to which the starch dispersed phase in the starch-based composite material is infiltrated by air and water, and having a better plasticizing effect, further improving the toughness of the material, and making specific components work synergistically through specific ratios to obtain a starch-based composite material with excellent toughness and at the same time maintaining good transparency.

[0083] In some embodiments of the present application, based on the total mass of the polyester material and the starch, the mass proportion of the polyester material is 50% to 80%.

[0084] In some embodiments of the present application, based on the total mass of the polyester material and the starch, the mass proportion of the starch is 20% to 50%.

[0085] The component ratio can be further adjusted to further improve the mechanical properties of starch-based composite materials.

[0086] If the mass proportion of the above-mentioned polyester material or starch is "15% to 85%", the mass proportion of the polyester material or starch includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiments and the following point values: 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%; or a range consisting of any two values, for example, it can be 15% to 20%, 15% to 25%, 15% to 35%, 15% to 40%, 15% to 45%, 15% to 50%, 15% to 55%, 15% to 60%, 15% to 65%, 15% to 70%, 15% to 75%, 15% to 80%, 20% to 35%, 20% to 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%, 3 0%~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%.

[0087] The above range "10% to 50%" includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Specific examples include but are not limited to the point values ​​in the embodiments and the following point values: 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%; or a range consisting of any two numerical values, for example, it can be 15% to 20%, 15% to 25%, 15% to 35%, 15% to 40%, 15% to 45%, 15% to 50%, 20% to 35%, 20% to 40%, 20% to 45%, 20% to 50%, 30% to 40%, 30% to 45%, 30% to 50%.

[0088] It can be understood that the average particle size of starch is greater than 0 and ≤1 μm.

[0089] In some embodiments of the present application, the functionality T of the hydroxyl group in the polyhydroxy compound satisfies: T≥3.

[0090] 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 the polyhydroxy compounds can form hydrogen bonds with the hydroxyl groups in the starch molecules, thereby replacing and reducing the hydrogen bonds within and between starch molecules, and preventing them from agglomerating themselves due to the formation of hydrogen bonds within and between starch molecules.

[0091] Optionally, T satisfies: 3≤T≤7.

[0092] Optionally, the polyhydroxy compound includes at least one of polyols and condensates thereof.

[0093] The polyol condensate may be a polyol ether formed by dehydration condensation of a polyol.

[0094] Optionally, the polyhydroxy compound includes at least one of a polyol and a polyol ether.

[0095] Optionally, the polyhydroxy compound includes at least one of glycerol, polyglycerol, sorbitol and mannitol.

[0096] In some embodiments, the polyester material comprises biodegradable polyester.

[0097] Biodegradable polyester has biodegradable properties and can further improve the biodegradability of starch-based composite materials.

[0098] 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.

[0099] It can be understood that the polyacid in the acid monomer can be polycondensed with the alcohol monomer through an esterification reaction to form polyester, and the ester derivative of the polyacid in the acid monomer can be polycondensed with the alcohol monomer through an ester exchange reaction to form polyester.

[0100] Optionally, the aromatic polyacid contains 6 to 20 carbon atoms.

[0101] Optionally, the aromatic polyacid contains 6 to 10 carbon atoms.

[0102] Optionally, the heteroaromatic polyacid contains 5 to 20 carbon atoms.

[0103] Optionally, the heteroaromatic polyacid contains 6 to 10 carbon atoms.

[0104] Optionally, the heteroatoms contained in the heteroaromatic group of the heteroaromatic polyacid include, but are not limited to, nitrogen and sulfur.

[0105] Optionally, the alicyclic polyacid contains 3 to 30 carbon atoms.

[0106] Optionally, the alicyclic polyacid contains 6 to 10 carbon atoms.

[0107] Optionally, the aliphatic polyacid contains 2 to 22 carbon atoms.

[0108] Optionally, the aliphatic polyacid contains 2 to 10 carbon atoms.

[0109] Optionally, the aliphatic polyol contains 2 to 22 carbon atoms.

[0110] Optionally, the aliphatic polyol contains 2 to 10 carbon atoms.

[0111] It should be noted that the functionality of the carboxylic acid group in the above-mentioned "polyacid" is ≥2, that is, dibasic acid and compounds containing more than two carboxyl groups; the functionality of the hydroxyl group in the above-mentioned "polyol" is ≥2, that is, diol and compounds containing more than two hydroxyl groups.

[0112] Optionally, the acid monomer includes at least one of aromatic dibasic acid, heteroaromatic dibasic acid, alicyclic dibasic acid, aliphatic dibasic acid and ester derivatives thereof.

[0113] Optionally, the acid monomer includes a first monomer and a second monomer, the first monomer includes at least one of an aromatic polyacid and an ester derivative thereof, and the second monomer includes an aromatic polyacid and an ester derivative thereof.

[0114] In this way, the simultaneous introduction of aromatic segments and aromatic segments into polyester materials is beneficial to improving the toughness of starch-based composite materials.

[0115] Optionally, based on the total molar number of the acid monomers, the molar mass of the first monomer accounts for 30% to 70%.

[0116] Optionally, based on the total molar number of the acid monomers, the molar mass of the first monomer accounts for 30% to 50%.

[0117] Optionally, the first monomer includes an aromatic dibasic acid; further, the first monomer may be at least one of terephthalic acid, phthalic acid, and furandicarboxylic acid.

[0118] Optionally, the second monomer includes an aliphatic dibasic acid; further, the second monomer may be at least one of adipic acid, pimelic acid, suberic acid, sebacic acid, azelaic acid, undecanedioic acid, dodecanedioic acid, and tridecanedioic acid.

[0119] In some embodiments, the monomers for preparing the biodegradable polyester further include a hydroxy acid having 3 to 10 carbon atoms.

[0120] Optionally, the hydroxy acid comprises at least one of lactic acid and hydroxyalkanoic acid.

[0121] In addition, hydroxyalkanoic acid refers to a monomer of polyhydroxyalkanoate (PHA).

[0122] Optionally, the hydroxy acid comprises lactic acid.

[0123] In some embodiments of the present application, the polyester material includes a copolymer of butylene adipate and butylene terephthalate and polylactic acid.

[0124] In some embodiments, the weight average molecular weight of the polylactic acid is 40,000 to 200,000.

[0125] In some embodiments of the present application, the polyester material is a copolymer of butylene adipate and butylene terephthalate.

[0126] Alternatively, the copolymer of butylene adipate and butylene terephthalate is polybutylene adipate / terephthalate (PBAT).

[0127] Optionally, in the hydrogen nuclear magnetic resonance spectrum of the polyester material, the integrated area of ​​the peak with a chemical shift of 5.0ppm to 5.3ppm is X, the integrated area of ​​the peak with a chemical shift of 8.1±0.5ppm is Y, and X and Y satisfy: 0.1≤X / Y≤0.3.

[0128] X represents the integral of the proton signal peak of the methine contained in the monomer lactic acid of polylactic acid PLA, and Y represents the integral of the proton signal peak on the benzene ring in polybutylene adipate / terephthalate (PBAT). The mass ratio of PLA and PBAT in the polyester material can be analyzed and calculated by the ratio of X / Y.

[0129] In some embodiments of the present application, the starch includes at least one of natural starch and its derivatives.

[0130] Optionally, the starch includes at least one of corn starch, potato starch, rice starch, tapioca starch, and esterified derivatives, etherified derivatives, and oxidized derivatives thereof.

[0131] In some embodiments of the present application, 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 for 3 hours in an environment of 25°C±2°C and 50RH%±5RH%, at which time the water contact angle is θ1, and it is continued to stand for 1 minute, at which time the water contact angle is θ2, H=θ1-θ2, and H satisfies: H>10°.

[0132] In some embodiments, when testing the H of a sample, three samples are taken and the above test steps are performed respectively to obtain three H values, and then the average value is taken.

[0133] Optionally, θ2<90°.

[0134] It can be understood that RH% stands for relative humidity, which refers to the percentage of the actual water vapor partial pressure in unit volume of air to the saturated water vapor pressure at the same temperature and volume.

[0135] Optionally, 10°<H≤30°

[0136] Optionally, 0≤θ2<90°.

[0137] In some embodiments, the weight average molecular weight of the polyester material is 40000 to 250000. In a second aspect of the present application, a method for preparing a starch-based composite material is provided, comprising the following step S10.

[0138] S10, mixing the components of the starch-based composite material of the first aspect, and melt-extruding.

[0139] In some embodiments of the present application, melt extrusion is performed using an extruder. Furthermore, the extruder can be a twin-screw extruder. Furthermore, the screw aspect ratio of the twin-screw extruder can be (40-48):1, and the screw aspect ratio can also be selected from any one of the following ratios or any two ratios: 40:1, 41:1, 42:1, 43:1, 44:1, 45:1, 46:1, 47:1, 48:1, etc.

[0140] In some embodiments of the present application, when an extruder (such as a twin-screw extruder) is used for melt extrusion, the screw speed can be 300-600 r / min; further, in the direction of material advancement, the screw 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.

[0141] Optionally, the screw speed can also be selected from any one of the following speeds or an interval consisting of any two speeds: 300r / min, 350r / min, 400r / min, 450r / min, 500r / min, 550r / min, 600r / min, etc.

[0142] Optionally, the extrusion speed is 400 kg / h to 600 kg / h.

[0143] In a third aspect of the present application, there is provided use of a starch-based composite material prepared by the preparation method of the starch-based composite material of the first aspect or the second aspect of the present application in the preparation of plastic products.

[0144] In a fourth aspect of the present application, a plastic product is provided, comprising the starch-based composite material of the first aspect or the starch-based composite material prepared by the preparation method of the starch-based composite material of the second aspect.

[0145] The above-mentioned starch-based composite material has excellent toughness and can maintain excellent toughness even when the thickness is <16μm: the elongation at break is >250%, the transverse tensile strength is >5MPa in 100% directional tensile strength, and the longitudinal tensile strength is >10MPa. When used to prepare plastic products, it can increase the service life of the products and help broaden their application range.

[0146] The embodiments of the present application will be described in detail below with reference to the examples. It should be understood that these examples are intended to illustrate the present application only and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are preferably referred to the guidance provided in the present application, and can also be based on the experimental manuals or conventional conditions in this area, or according to the conditions recommended by the manufacturer, or with reference to experimental methods known in the art.

[0147] In the following specific examples, the measured parameters of raw material components may have slight deviations within the range of weighing accuracy unless otherwise specified. For temperature and time parameters, acceptable deviations caused by instrument testing accuracy or operational accuracy are allowed.

[0148] Some specific examples are provided below.

[0149] 1. Raw materials

[0150] In the following examples, unless otherwise stated, the sources of raw materials are as follows:

[0151] Polyester material A: polybutylene adipate / terephthalate (PBAT), Zhuhai Jinfa Biomaterials Co., Ltd. The weight average molecular weight is 120,000;

[0152] Polyester material B: Polylactic acid: (Ingeo TM 4060D), and a weight average molecular weight of 110,000.

[0153] Polyester material A and polyester material B were mixed to obtain a mixed polyester material. The mixed polyester material was subjected to H NMR spectroscopy. The integrated area of ​​the peak with a chemical shift of 5.0 ppm to 5.3 ppm was X, and the integrated area of ​​the peak with a chemical shift of 8.1±0.5 ppm was Y. The specific ratio of X / Y is shown in Table 1.

[0154] Starch: Edible corn starch from Shandong Shouguang Juneng Golden Corn Development Co., Ltd. can be sieved with molecular sieves or other particle size screening devices to screen out starch of different particle sizes.

[0155] Polyhydroxy compounds: glycerol, sorbitol and mannitol, commercially available.

[0156] 2. Preparation Method

[0157] Unless otherwise specified, the following equipment is used:

[0158] The starch-based composite materials and plastic products of the following examples and comparative examples were prepared by the following method:

[0159] S1: Weigh and premix the components according to the raw material ratio shown in Table 1 to obtain a premix. The average particle size of the starch is 0.6 μm.

[0160] S2: The premix prepared in step S1 is put into a twin-screw extruder for melt blending and extrusion granulation. The screw aspect ratio is 40:1, and the set temperatures are: 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, die head: 175°C, screw speed: 300 rpm, extrusion speed: 500 kg / h, to prepare a starch-based composite material.

[0161] S3: A batch of 15 ± 1 μm film products were prepared from the starch-based composite material on a single-screw film blowing machine with a screw diameter of 45 cm and an aspect ratio of 20:1. The average apparent thickness D1 was tested according to ISO 4593:1993. The specific thickness is shown in Table 1.

[0162] The same batch of starch-based composite materials was used to prepare a batch of film products with a thickness of >16 μm on a single-screw film blowing machine. The average apparent thickness D2 was tested according to ISO 4593:1993. The specific thickness is shown in Table 1.

[0163] S4: Testing

[0164] 1. The surface of a thin film product with a thickness of 15±1 μm was etched with 5M hydrochloric acid and then subjected to gold spraying. The surface was observed using a scanning electron microscope (SEM, JSM-6330F, Tokyo, Japan) at a voltage of 15 kV. The electron microscope image of the thin film product with a thickness of 15±1 μm prepared in Example 1 is shown in FIG1 .

[0165] The size and distribution of the pores in the film products were analyzed by image analysis software (Image Pro plus 6). Data within the range of 100 × 100 μm were measured for each sample. The average particle size was calculated by testing 10 samples and recorded as R, which is the average particle size of starch in the film.

[0166] 2. Cut a film product with a thickness of 15±1μm into a square film of 1cm×1cm size, place it in an environment of 25±2℃, 50±5RH% and stabilize it for 3 hours, then use a surface contact angle meter (KRUSSDSA10-MK) to measure the initial contact angle θ1 of the sample surface, and then measure the surface contact angle θ2 of the sample again after standing for 1 minute, H=θ1-θ2, take 3 samples for measurement and calculate the average value H.

[0167] Among them, the photo of the initial contact angle θ1 of the film product surface of Example 1 is shown in Figure 3, and the photo of the stable contact angle θ2 is shown in Figure 4. It can be clearly seen that the water wetting area of ​​the film product surface becomes larger, that is, the contact angle becomes smaller.

[0168] 3. The 100% directional tensile strength and elongation at break of a 15±1 μm film product were tested using ISO 527-3, where MD = machine direction and TD = transverse direction.

[0169] The raw material formulas and experimental results of Examples 1 to 10 and Comparative Examples 1 to 5 can be found in Table 1. Among them, the molecular sieve can be used to sieve out corn starch of different particle sizes. The particle sizes of the corn starch used in Examples 1 to 10 and Comparative Examples 1 to 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.

[0170] The photograph of the initial contact angle θ1 of the film product surface of Comparative Example 1 is shown in FIG5 , and the photograph of the stable contact angle θ2 is shown in FIG6 .

[0171] Among them, the mass proportion of polyester material and starch is calculated based on the total mass of polyester material and starch, and the mass proportion of polyhydroxy compound is calculated based on the mass of starch.

[0172] Table 1

[0173] Note: “ / ” means the substance does not exist.

[0174] Furthermore, the materials prepared in the above examples and comparative examples were prepared into 18±1 μm film products on a single-screw film blowing machine with a screw diameter of 45 cm and an aspect ratio of 20:1, and their transparency was tested. The transmittance and haze tests were performed with reference to the standard GB / T2410-200. The higher the transmittance and the lower the haze, the better the transparency. The specific results are shown in Table 2.

[0175] Table 2

[0176] From the data analysis of Tables 1 and 2, it can be seen that the starch-based composite material of the present application has excellent toughness and can maintain excellent toughness even when the thickness is ≤16 μm. When used to prepare plastic products, it can increase the service life of the products. When the thickness is ≥16 μm, it can still maintain good transparency, which is conducive to broadening its application range.

[0177] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0178] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that variations and improvements are possible within the scope of the present application, as would be apparent to one skilled in the art. These variations and improvements fall within the scope of the present application. Therefore, the scope of protection of the present patent application shall be determined by the appended claims.

Claims

1. A starch-based composite material, the components of which include: Polyester materials, starch and polyols; Wherein, based on the total mass of the polyester material and the starch, the mass of the polyester material accounts for 15% to 85%, and the mass of the starch accounts for 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.

2. The starch-based composite material according to claim 1, wherein: Based on the total mass of the polyester material and the starch, the mass of the polyester material accounts for 50% to 80%.

3. The starch-based composite material according to any one of claims 1 to 2, wherein: Based on the total mass of the polyester material and the starch, the mass proportion of the starch is 20% to 50%.

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

5. The starch-based composite material according to any one of claims 1 to 4, wherein: The functionality T of the hydroxyl group in the polyhydroxy compound satisfies: 3≤T≤7.

6. The starch-based composite material according to any one of claims 1 to 5, wherein: The polyhydroxy compound includes at least one of polyols and condensates thereof.

7. The starch-based composite material according to any one of claims 1 to 6, wherein: The polyhydroxy compound includes at least one of a polyol and a polyol ether.

8. The starch-based composite material according to any one of claims 1 to 7, wherein: The polyhydroxy compound includes at least one of glycerol, polyglycerol, sorbitol and mannitol.

9. The starch-based composite material according to any one of claims 1 to 8, wherein: The polyester material includes biodegradable polyester.

10. The starch-based composite material according to claim 9, wherein: 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. The alcohol monomers include aliphatic polyols.

11. The starch-based composite material according to claim 10, wherein: The aromatic polyacid contains 6 to 20 carbon atoms.

12. The starch-based composite material according to claim 10, wherein: The heteroaromatic polyacid contains 5 to 20 carbon atoms.

13. The starch-based composite material according to any one of claims 10 to 12, wherein: The alicyclic polybasic acid contains 3 to 30 carbon atoms.

14. The starch-based composite material according to any one of claims 10 to 13, wherein: The aliphatic polybasic acid contains 2 to 22 carbon atoms.

15. The starch-based composite material according to any one of claims 10 to 14, wherein: The aliphatic polyol contains 2 to 22 carbon atoms.

16. The starch-based composite material according to any one of claims 10 to 15, wherein: The acid monomer includes a first monomer and a second monomer, the first monomer includes at least one of an aromatic polyacid and an ester derivative thereof, and the second monomer includes an aliphatic polyacid and an ester derivative thereof.

17. The starch-based composite material according to claim 16, wherein: Based on the total molar number of the acid monomers, the molar mass of the first monomer accounts for 30% to 70%.

18. The starch-based composite material according to any one of claims 16 to 17, wherein: The first monomer includes an aromatic dibasic acid.

19. The starch-based composite material according to any one of claims 16 to 18, wherein: The first monomer is at least one of terephthalic acid, phthalic acid and furandicarboxylic acid.

20. The starch-based composite material according to any one of claims 16 to 19, wherein: The second monomer includes an aliphatic dibasic acid.

21. The starch-based composite material according to any one of claims 16 to 20, wherein: The second monomer is at least one of adipic acid, pimelic acid, suberic acid, sebacic acid, azelaic acid, undecanedioic acid, dodecanedioic acid, and tridecanedioic acid.

22. The starch-based composite material according to any one of claims 10 to 21, wherein: The monomers for preparing the biodegradable polyester also include hydroxy acids with 3 to 10 carbon atoms.

23. The starch-based composite material according to claim 22, wherein: The hydroxy acids include lactic acid.

24. The starch-based composite material according to any one of claims 1 to 23, wherein: The polyester material includes a copolymer of butylene adipate and butylene terephthalate and polylactic acid.

25. The starch-based composite material according to any one of claims 1 to 24, wherein: In the nuclear magnetic resonance hydrogen spectrum of the polyester material, the integrated area of ​​the peak with a chemical shift of 5.0ppm to 5.3ppm is X, the integrated area of ​​the peak with a chemical shift of 8.1±0.5ppm is Y, and X and Y satisfy: 0.1≤X / Y≤0.

3.

26. The starch-based composite material according to any one of claims 1 to 25, wherein: The starch includes at least one of natural starch and its derivatives.

27. The starch-based composite material according to any one of claims 1 to 26, wherein: The starch includes at least one of corn starch, potato starch, rice starch, tapioca starch and their esterified derivatives, etherified derivatives and oxidized derivatives.

28. The starch-based composite material according to any one of claims 1 to 27, wherein: The water contact angle of the starch-based composite material satisfies: the starch-based composite material is allowed to stand for 3 hours in an environment of 25°C±2°C and 50RH%±5RH%, at which time the water contact angle is θ1; the water droplets are allowed to stand on the surface of the starch-based composite material for 1 minute, at which time the water contact angle is θ2, H=θ1-θ2, and H satisfies: H>10°.

29. The starch-based composite material according to claim 28, wherein: θ2<90°.

30. A method for preparing a starch-based composite material, wherein: The steps include: The components of the starch-based composite material according to any one of claims 1 to 29 are mixed and melt-extruded.

31. Use of the starch-based composite material according to any one of claims 1 to 29 or the starch-based composite material prepared by the method for preparing the starch-based composite material according to claim 30 in the preparation of plastic products.

32. A plastic product, wherein: The invention comprises the starch-based composite material according to any one of claims 1 to 29 or a starch-based composite material prepared by the preparation method of the starch-based composite material according to claim 30.

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