Biodegradable polyester prepolymer resin, its preparation method and use

Abstract

This application relates to the technical field of biodegradable polyester resins, and more particularly to a biodegradable polyester prepolymer resin, its preparation method, and its application. The biodegradable polyester prepolymer resin comprises an unsaturated aliphatic polyester, which includes the following components: residues of a saturated aliphatic diacid, residues of an unsaturated aliphatic diacid, residues of a saturated aliphatic triol, and residues of a saturated aliphatic diol. This application can prepare a biodegradable polyester prepolymer resin using saturated aliphatic diacid, unsaturated aliphatic diacid, saturated aliphatic triol, and saturated aliphatic diol, giving it excellent adhesive and water resistance properties, while also exhibiting good biodegradability, making it more environmentally friendly and playing a role in green environmental protection.

Description

Technical Field

[0001] This application relates to the technical field of biodegradable polyester resins, and more particularly to a biodegradable polyester prepolymer resin, its preparation method, and its application. Background Technology

[0002] With societal progress, adhesives have developed rapidly, with their performance continuously improved and their applications expanding daily. Whether in high-tech fields or everyday life, adhesives play a crucial and irreplaceable role. Common adhesives include epoxy resins, phenolic resins, urea-formaldehyde resins, polyurethane, polyvinyl acetate, polyvinyl alcohol and acetal resins, polystyrene, nitrile rubber, chloroprene rubber, polysulfide rubber, and silicone rubber. Due to their unique chemical structures and properties, these adhesives are difficult to degrade in the natural environment. Therefore, their long-term presence in the environment has become a major hidden danger in modern society.

[0003] In related technologies, photocuring is a common resin curing process that can reduce the use of solvents and improve environmental friendliness. However, photocured resins have a high degree of cross-linking after curing and cannot be biodegraded, still causing great pollution to the environment.

[0004] Therefore, there is an urgent need to develop a biodegradable material with excellent bonding properties, good processing performance, and environmentally friendly processing.

[0005] It should be noted that the above content is not necessarily prior art, nor is it intended to limit the scope of patent protection of this application. Summary of the Invention

[0006] This application provides a biodegradable polyester prepolymer resin, its preparation method, and its application to solve or alleviate one or more of the technical problems mentioned above.

[0007] In a first aspect, embodiments of this application provide a biodegradable polyester prepolymer resin, comprising: An unsaturated aliphatic polyester, wherein the unsaturated aliphatic polyester comprises the following components in molar proportions: 90-110 parts of saturated aliphatic dicarboxylic acid residues. 5-20 parts of unsaturated aliphatic dicarboxylic acid residues. 40-88 residues of saturated aliphatic triols 30-80 parts of saturated aliphatic diol residues.

[0008] Optionally, the unsaturated aliphatic polyester further includes residues of polycaprolactone polyol, and the molar fraction of the residues of the polycaprolactone polyol is 5 to 30 parts. The residues of the polycaprolactone polyol include one or both of the residues of polycaprolactone diol and polycaprolactone triol.

[0009] Optionally, the molecular weight of the residues of the polycaprolactone polyol is less than 1000 g / mol.

[0010] Optionally, the residues of the saturated aliphatic dicarboxylic acid include one or more of the following: succinic acid residues, glutaric acid residues, adipic acid residues, octanoic acid residues, and sebacic acid residues.

[0011] Optionally, the residues of the unsaturated aliphatic dicarboxylic acid include one or more of the following: residues of fumaric acid, maleic acid, and itaconic acid.

[0012] Optionally, the residues of the saturated aliphatic triol are residues of glycerol.

[0013] Optionally, the residues of the saturated aliphatic diol include one or more of the following: residues of propylene glycol, residues of butanediol, and residues of hexanediol.

[0014] Optionally, the alkyd ratio of the unsaturated aliphatic polyester is 1.0 to 1.3.

[0015] Secondly, embodiments of this application provide a method for preparing a biodegradable polyester prepolymer resin, comprising the following steps: According to the molar parts, saturated aliphatic dicarboxylic acid, unsaturated aliphatic dicarboxylic acid, saturated aliphatic triol and saturated aliphatic diol are added to the reactor, then the vacuum pump is turned on and the temperature is raised and stirred. When the reaction is completed, the vacuum pump is turned off to obtain unsaturated aliphatic polyester. The temperature is controlled to decrease, and then the additives are added to the reactor and stirred to obtain biodegradable polyester prepolymer resin.

[0016] Thirdly, embodiments of this application provide an application of the above-described biodegradable polyester prepolymer resin in adhesives and packaging materials.

[0017] The embodiments of this application employing the above-described technical solution may have the following advantages: The biodegradable polyester prepolymer resin provided in this application includes unsaturated aliphatic polyester, and the unsaturated aliphatic polyester contains residues of saturated aliphatic dicarboxylic acid, residues of unsaturated aliphatic dicarboxylic acid, residues of saturated aliphatic triol, and residues of saturated aliphatic diol. This gives the biodegradable polyester prepolymer resin excellent adhesive properties and water resistance, while also having good biodegradability, making it more environmentally friendly and playing a green and environmentally friendly role. Detailed Implementation The embodiments of this application are described in detail below. These embodiments are exemplary and are only used to explain this application, and should not be construed as limiting this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0018] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this disclosure, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion. And the discussion of a second element, component, area, layer, or portion does not imply that the first element, component, area, layer, or portion necessarily exists in this application.

[0019] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0020] It should be noted that the terms "first," "second," etc., used in the specification and claims of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0021] In this application, when numerical intervals (i.e., numerical ranges) are involved, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed in this application 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, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, etc.

[0022] The following provides a definition of the terminology used in this application.

[0023] The residues of saturated aliphatic dicarboxylic acids: refer to the portion of saturated aliphatic dicarboxylic acids or anhydrides that remains in the ester after undergoing an esterification reaction with an alcohol.

[0024] The residues of saturated aliphatic triols refer to the portion of saturated aliphatic triols that remain in the ester after the esterification reaction with carboxylic acids.

[0025] The residues of saturated aliphatic diols refer to the portion of the hydroxyl group of a saturated aliphatic diol that remains in the ester after the esterification reaction of the hydroxyl group with a carboxylic acid.

[0026] The residues of unsaturated aliphatic dicarboxylic acids refer to the remaining part of an unsaturated aliphatic dicarboxylic acid molecule after it has undergone an esterification reaction with other monomers (such as diols or triols).

[0027] The residues of polycaprolactone polyols refer to the portion of polycaprolactone polyols that remain in the ester after undergoing an esterification reaction with a carboxylic acid or alcohol.

[0028] Photocuring: refers to the chemical change in which prepolymers can cross-link and cure under light to form a network structure.

[0029] Polyester prepolymers refer to a class of substances that have two or more reactive functional groups, such as hydroxyl, carboxyl, carbon-carbon double bonds (C=C), and vinyl ether, and can undergo cross-linking reactions through light, heating, chemical catalysis, etc., to form cross-linked and cured macromolecules.

[0030] To facilitate understanding of the technical solutions provided in the embodiments of this application by those skilled in the art, the relevant technologies are described below: With increasing environmental awareness and the continuous improvement of environmental regulations, environmentally friendly adhesives are gradually gaining attention, among which biodegradable adhesives are the most ideal. These adhesives degrade under natural or composting conditions due to the action of naturally occurring microorganisms, ultimately degrading completely into carbon dioxide (or methane), water, mineralized inorganic salts of their constituent elements, and new biomass.

[0031] Biodegradable polyester polymers include polylactic acid (PLA), polybutylene terephthalate (PBAT), polybutylene succinate and its adipic acid copolymer (PBS / PBSA), polyhydroxyalkanoates (PHA), and polypropylene carbonate (PPC). PBAT and PPC are derived from fossil resources and are non-renewable, thus not conforming to the concept of sustainable development. PBS / PBSA is partly derived from biological resources. PLA and PHA are 100% bio-based, conforming to the concept of sustainable development; however, they have high crystallinity, high hardness, low elongation, and high brittleness, often lacking tackiness at room temperature and exhibiting poor adhesive properties, making them unsuitable for use as adhesives. In summary, there are currently no environmentally friendly (naturally biodegradable) biodegradable materials on the market that can be easily prepared through photocuring.

[0032] It should be noted that biodegradation refers to the ability of microorganisms to break down prepolymers into smaller molecules under various standard conditions, such as in industrial composting, household composting, soil burial, freshwater, or seawater. Generally, industrial composting is the easiest form of degradation, while seawater degradation is the most difficult. Photocuring refers to the chemical change in which prepolymers can cross-link and solidify under light to form a network structure. The prepolymer refers to a class of substances that have not yet cross-linked and solidified. Polyester prepolymers refer to a class of substances possessing two or more reactive functional groups, such as hydroxyl, carboxyl, carbon-carbon double bonds (C=C), and vinyl ethers, and capable of undergoing cross-linking reactions through light, heating, or chemical catalysis to form cross-linked and solidified macromolecules.

[0033] To address the aforementioned issues, the applicant conducted extensive research on biodegradable materials. The results showed that aliphatic polyesters typically have relatively simple molecular chain structures, with complex aromatic rings or durable chemical bonds within the chains, making them more susceptible to microbial decomposition. Aliphatic chains are generally more easily recognized and degraded by enzymes in microorganisms. Therefore, further research was conducted based on this understanding, resulting in the preparation of biodegradable materials with excellent adhesive and water-resistant properties.

[0034] Therefore, this application provides a technical solution for a biodegradable polyester prepolymer resin, its preparation method, and its application, as detailed below.

[0035] The raw materials used in the embodiments and comparative examples of this application are as follows: Saturated aliphatic dicarboxylic acids A1: Succinic acid, produced by Bohr Chemicals.

[0036] A2: Adipic acid, produced by Sinopharm Chemical Reagent Co., Ltd.

[0037] A3: Oxalic acid, produced by Sinopharm Chemical Reagent Co., Ltd.

[0038] A4: Sebacic acid, produced by Hebei Kaide Biomaterials Co., Ltd.

[0039] Saturated aliphatic triols B1: Glycerol, produced by Nature Glycerin Company, Malaysia.

[0040] B2: Glycerol, produced by Shanghai Nanxiang Reagent Co., Ltd.

[0041] Polycaprolactone polyol C1: Polycaprolactone triol, molecular weight 300 g / mol, produced by Hunan Juren New Material Technology Co., Ltd.

[0042] C2: Polycaprolactone triol, molecular weight 2000 g / mol, produced by Hunan Juren New Material Technology Co., Ltd.

[0043] C3: Polycaprolactone diol, molecular weight 2000 g / mol, produced by Hunan Juren New Material Technology Co., Ltd.

[0044] C4: Polycaprolactone diol, molecular weight 3000 g / mol, produced by Hunan Juren New Material Technology Co., Ltd.

[0045] Saturated aliphatic diols D1: 1,4-Butanediol, produced by Yuanli Chemical Group Co., Ltd.

[0046] D2: 1,6-hexanediol, produced by Liaoyang Petrochemical Company.

[0047] D3: 1,3-Butanediol, produced by Sinopharm Reagent.

[0048] D4: 1,2-Propylene glycol, produced by Sinopharm Reagent.

[0049] Unsaturated aliphatic dicarboxylic acids E1: Fumaric acid, produced by Xuelang Biotechnology Co., Ltd.

[0050] E2: Maleic acid, produced by Liaoyang Petrochemical Company.

[0051] E3: Itaconic acid, produced by Jinan Xuanhao Chemical Co., Ltd.

[0052] Photoinitiators F1: OMPP, manufactured by German company Liangzhi Chemical (China) Co., Ltd.

[0053] F2: MBZ, manufactured by German Refined Chemicals (China) Co., Ltd.

[0054] F3: EDB, manufactured by German Refined Chemicals (China) Co., Ltd.

[0055] Exemplary embodiments according to this application will now be described in more detail. It should be understood that these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein.

[0056] This application provides a biodegradable polyester prepolymer resin. The biodegradable polyester prepolymer resin may include unsaturated aliphatic polyesters, which comprise the following components in molar proportions: 90-110 parts of saturated aliphatic dicarboxylic acid residues. 5-20 parts of unsaturated aliphatic dicarboxylic acid residues. 40-88 residues of saturated aliphatic triols 30-80 parts of saturated aliphatic diol residues; In some embodiments, the biodegradable polyester prepolymer resin further includes additives, including one or more of photoinitiators, reactive diluents, plasticizers, anti-hydrolysis agents, and fillers.

[0057] In this embodiment, the biodegradable polyester prepolymer resin provided by this application includes unsaturated aliphatic polyester, and the unsaturated aliphatic polyester contains residues of saturated aliphatic dicarboxylic acid, residues of unsaturated aliphatic dicarboxylic acid, residues of saturated aliphatic triol and residues of saturated aliphatic diol, which gives it excellent adhesion and water resistance, and at the same time, it also has good biodegradability, making it more environmentally friendly and playing a green and environmentally friendly role.

[0058] It should be noted that aliphatic polyesters are a class of linear polymers formed by the repeated linkage of residues of aliphatic dicarboxylic acids and aliphatic diols (or hydroxy acid residues) through ester bonds (-O-CO-). Their main chain does not contain aromatic ring structures, unlike aromatic polyesters containing benzene rings (such as PET). Aliphatic polyesters can be classified into saturated and unsaturated aliphatic polyesters based on the presence or absence of unsaturated bonds. In saturated aliphatic polyesters, there is only one covalent bond between carbon atoms, while in unsaturated aliphatic polyesters, some carbon atoms are connected by more than one covalent bond. Specifically, the unsaturated aliphatic polyesters in this application refer to a class of polymers formed by the polycondensation reaction of aliphatic polyols and aliphatic polyacids (or anhydrides) containing unsaturated double bonds. Their main chain contains at least one carbon-carbon double bond (C=C), and their molecular structure does not contain aromatic rings or other aromatic structures.

[0059] Photoinitiators are compounds that absorb photon energy and generate reactive intermediates (such as free radicals, cations, or anions) under specific wavelengths of light radiation. Their function is to accelerate the photocuring reaction of monomers or prepolymers. Based on the type of reactive intermediate, photoinitiators can be divided into two main categories: free radical photoinitiators and ionic photoinitiators. Free radical photoinitiators generate free radicals through homolytic cleavage or hydrogen extraction reactions after photoexcitation, which then initiate free radical chain polymerization of unsaturated systems. Ionic photoinitiators generate cationic (such as protic acids) or anionic reactive species through heterolytic cleavage under light irradiation, initiating cationic or anionic polymerization of monomers such as epoxy resins and vinyl ethers. Photoinitiators can also be classified according to the absorption peak wavelength: UVC photoinitiators (absorption band 200–280 nm), UVB photoinitiators (absorption band 280–315 nm), and UVA photoinitiators (absorption band 315–400 nm). Shorter wavelengths of light have higher energy but weaker penetrating power.

[0060] Reactive diluents are diluents that participate in the chemical reaction during polymerization and ultimately become part of the cured product. They are commonly used in resin systems to improve the processability of the resin by reducing its viscosity, and simultaneously react with the resin during curing to enhance the properties of the final material. Reactive diluents can be one or more of styrene, methyl methacrylate (MMA), vinylbenzene, and acrylates.

[0061] Plasticizers are substances that improve the flexibility and processability of resins through physical actions (such as intermolecular interactions). However, plasticizers do not participate in the chemical reactions of the resin and therefore do not become part of the cured product. Inactive plasticizers are typically used to improve the ductility, flexibility, and low-temperature properties of polymers. Common inactive plasticizers include phthalates (such as DEHP and DBP), fatty acid esters (such as DOA), phosphate esters (such as TPP), and citrate esters (such as TEC).

[0062] Anti-hydrolysis agents are additives used to prevent materials from undergoing hydrolysis in humid or aquatic environments. Hydrolysis can lead to material degradation and performance decline; therefore, anti-hydrolysis agents are needed in some water-sensitive resin and polymer systems to improve their hydrolysis resistance. Common anti-hydrolysis agents include triazine compounds, certain amino compounds in epoxy resins, and certain compounds with hydrophilic groups.

[0063] Fillers are solid substances used to increase the volume of materials, improve their physical properties, or reduce costs. Fillers typically do not participate in the chemical reaction of resins; instead, they function as part of the reinforcing material, improving the performance of the final product by altering its structure or increasing its hardness, rigidity, and thermal stability. Common fillers include calcium carbonate, talc, wollastonite, glass fiber, and bauxite.

[0064] In optional embodiments, the unsaturated aliphatic polyester further includes residues of polycaprolactone polyol, and the molar fraction of the polycaprolactone polyol residues is 5-30 parts; wherein the polycaprolactone polyol residues include one or both of polycaprolactone diol residues and polycaprolactone triol residues. More preferably, the molar fraction of the polycaprolactone polyol residues is 10-20 parts. The polycaprolactone polyol residues exist in the unsaturated aliphatic polyester in the form of continuous hydroxyhexanoic acid residues and polyol residues. The hydroxyhexanoic acid residues refer to the portion remaining in the ester after the hydroxyhexanoic acid undergoes an esterification reaction with an acid or alcohol. Structurally, the polycaprolactone diol residues and polycaprolactone triol residues are shown in Formulas A and B below:

[0065] Formula A and Formula B In this embodiment, polycaprolactone polyol is biodegradable and has good hydrophobicity, making it a suitable monomer for improving the water resistance of unsaturated aliphatic polyesters. Since polycaprolactone polyol itself lacks adhesive properties, a molar fraction greater than 30 parts of polycaprolactone polyol residues leads to poor adhesive properties in the unsaturated aliphatic polyester, while a molar fraction less than 5 parts does not effectively improve its water resistance. Therefore, when the molar fraction of polycaprolactone polyol residues is between 5 and 30 parts, the unsaturated aliphatic polyester exhibits both good water resistance and good adhesive properties.

[0066] In optional embodiments, the molecular weight of the residues of the polycaprolactone polyol is less than 1000 g / mol. More preferably, the molecular weight of the residues of the polycaprolactone polyol is less than 500 g / mol.

[0067] In this embodiment, the molecular weight of the residues of polycaprolactone polyol affects the performance of unsaturated aliphatic polyester. When the molecular weight of the residues of polycaprolactone polyol is greater than 1000 g / mol, the chain segments of the residues of polycaprolactone polyol are enriched together and cannot effectively protect the unsaturated aliphatic polyester as a whole. This will make the unsaturated aliphatic polyester more susceptible to local hydrolysis, thereby affecting the water resistance of the unsaturated aliphatic polyester.

[0068] In optional embodiments, the residues of the saturated aliphatic dicarboxylic acid include one or more residues of succinic acid, glutaric acid, adipic acid, octanoic acid, and sebacic acid. More preferably, when the residues of the saturated aliphatic dicarboxylic acid include a sebacic acid residue, the remaining residues of the saturated aliphatic dicarboxylic acid are one of the residues of succinic acid, glutaric acid, adipic acid, and octanoic acid.

[0069] In this embodiment, the residues of saturated aliphatic diacids refer to the ester portion remaining after the esterification reaction of saturated aliphatic diacids or anhydrides with alcohols. Aliphatic diacids are compounds in which two carboxyl groups are linked to a saturated aliphatic hydrocarbon, and saturated aliphatic hydrocarbons are hydrocarbons without double bonds in a cyclic structure. Anhydrides are cyclic compounds formed by the dehydration of the carboxyl groups of a diacid. The residues of saturated aliphatic diacids serve as one of the structural units of unsaturated aliphatic polyesters. The longer the carbon chain of the saturated aliphatic diacid residue, the lower the polar bond density of the unsaturated aliphatic polyester, resulting in poorer adhesion and better water resistance. Therefore, selecting the aforementioned residues of saturated aliphatic diacids not only improves the adhesion of the biodegradable polyester prepolymer resin but also provides good water resistance.

[0070] In an optional embodiment, the residues of the unsaturated aliphatic dicarboxylic acid include one or more of the following: residues of fumaric acid, maleic acid, and itaconic acid.

[0071] In this embodiment, the residues of the unsaturated aliphatic dicarboxylic acid contain carbon-carbon double bonds (C=C). These double bonds can undergo addition reactions under light conditions. Therefore, unsaturated aliphatic polyesters can undergo addition reactions under light conditions to form a network structure, which has better mechanical properties and water resistance.

[0072] In an optional embodiment, the residues of the saturated aliphatic triol are residues of glycerol.

[0073] In this embodiment, the residues of saturated aliphatic triols refer to the portion remaining in the ester after the esterification reaction of saturated aliphatic triols with carboxylic acids. Saturated aliphatic triols are compounds with three hydroxyl groups linked to saturated aliphatic hydrocarbons. As one of the structural units of unsaturated aliphatic polyesters, the residues of saturated aliphatic triols increase the adhesiveness of the unsaturated aliphatic polyester. Furthermore, glycerol is generally derived from biomass, which is beneficial for sustainable development. It should be noted that the content of saturated aliphatic triol residues can affect the performance of unsaturated aliphatic polyesters. When the content of saturated aliphatic triol residues is too low, the adhesive properties of the unsaturated aliphatic polyester will be poor. Conversely, when the content of saturated aliphatic triol residues is too high, it will lead to excessive cross-linking during the synthesis of the unsaturated aliphatic polyester, resulting in gelation at low molecular weights, making it difficult to obtain large molecules, and ultimately resulting in poor cohesion of the unsaturated aliphatic polyester.

[0074] In optional embodiments, the residues of the saturated aliphatic diol include one or more of the residues of propylene glycol, butanediol, and hexanediol. More preferably, the saturated aliphatic diol is one or both of the residues of 1,4-butanediol and 1,6-hexanediol.

[0075] In this embodiment, the residues of saturated aliphatic diols refer to the portion remaining in the ester after the hydroxyl groups of a saturated aliphatic diol react with a carboxylic acid. Saturated aliphatic diols refer to compounds in which two hydroxyl groups are linked to a saturated aliphatic hydrocarbon, such as ethylene glycol, propylene glycol, butanediol, hexanediol, octanediol, decanediol, lauryl glycol, etc. As one of the structural units of unsaturated aliphatic polyesters, the longer the carbon chain of the saturated aliphatic diol residues, the lower the polar bond density of the polyester, resulting in poorer adhesive properties but better water resistance. Therefore, selecting the aforementioned saturated aliphatic diol residues not only ensures good adhesive properties of the biodegradable polyester prepolymer resin but also provides good water resistance.

[0076] In an optional embodiment, the alkyd ratio of the unsaturated aliphatic polyester is 1.0 to 1.3. More preferably, the alkyd ratio of the unsaturated aliphatic polyester is 1.15 to 1.25.

[0077] In this embodiment, the alkyd-acid ratio refers to the ratio of the sum of the molar amounts of residues of aliphatic triols, aliphatic diols, and polycaprolactone polyols in the unsaturated aliphatic polyester to the sum of the molar amounts of residues of unsaturated aliphatic diacids and saturated aliphatic diacids. Free carboxyl groups make it easier for water molecules to wet the unsaturated aliphatic polyester, and free carboxyl groups act as catalysts for hydrolysis reactions. Therefore, excessive diacids lead to more free carboxyl groups in the unsaturated aliphatic polyester, resulting in poorer water resistance. However, insufficient diacids cause the esterification reaction to reach equilibrium at a small molecular weight, preventing the formation of large-molecule polyesters. Therefore, in the monomers for synthesizing unsaturated aliphatic polyesters, alcohols need to be slightly more abundant than acids. It should be noted that during the adjustment of the alkyd-acid ratio, unsaturated aliphatic polyesters with different alkyd-acid ratios exhibit better adhesion and water resistance at specific viscosities. For example, when the alkyd-acid ratio is 1.0, the unsaturated aliphatic polyester exhibits optimal performance with a viscosity of 3000~4000 mPa·s at 120°C; 2000~3000 mPa·s when the alkyd-acid ratio is 1.1; and 1000~1500 mPa·s when the alkyd-acid ratio is 1.2. When the alkyd-acid ratio exceeds these ranges, excessive free hydroxyl or carboxyl groups at the end of the reaction will undergo transesterification with the unsaturated aliphatic polyester, making it difficult to obtain unsaturated aliphatic polyesters with sufficiently large molecular weights, thus resulting in poor cohesion.

[0078] This application embodiment may also provide a method for preparing a biodegradable polyester prepolymer resin.

[0079] The preparation method includes the following steps: According to the molar ratio, saturated aliphatic dicarboxylic acid, unsaturated aliphatic dicarboxylic acid, saturated aliphatic triol and saturated aliphatic diol are added to the reactor, then the vacuum pump is turned on and the temperature is raised and stirred. When the viscosity reaches the target value, the vacuum pump is turned off to obtain unsaturated aliphatic polyester. The temperature is controlled to decrease, and then the additives are added to the reactor and stirred to obtain biodegradable polyester prepolymer resin.

[0080] This application also provides an application of biodegradable polyester prepolymer resin in adhesives and packaging materials. The biodegradable polyester prepolymer resin can be used to make adhesives or packaging materials, which can be degraded through home composting or soil burial after use.

[0081] The following specific embodiments provide a more detailed description of this application, but should not be construed as limiting the application. Any modifications or substitutions made to the methods, steps, or conditions of this application without departing from the spirit and substance of this application are within the scope of this application.

[0082]

Example 1

[0083] Example 2 - Example 26 The biodegradable polyester prepolymer resins of Examples 2-26 were prepared according to the preparation method of Example 1, except that the formulations of Examples 2-26 were different. The formulations of the biodegradable polyester prepolymer resins of Examples 1-26 are shown in Table 1.

[0084] Comparative Example 1 - Comparative Example 3 Biodegradable polyester prepolymer resins of Comparative Examples 1-3 were prepared according to the preparation method of Example 1, except that the formulations of Comparative Examples 1-3 were different. The formulations of the biodegradable polyester prepolymer resins of Comparative Examples 1-3 are shown in Table 1.

[0085] Table 1: Formulations of biodegradable polyester prepolymer resins in Examples 1-26 and Comparative Examples 1-3

[0086] Table 1 (continued): Formulations of biodegradable polyester prepolymer resins in Examples 1-26 and Comparative Examples 1-3

[0087] Table 1 (continued): Formulations of biodegradable polyester prepolymer resins in Examples 1-26 and Comparative Examples 1-3

[0088] Table 1 (continued): Formulations of biodegradable polyester prepolymer resins in Examples 1-26 and Comparative Examples 1-3

[0089] Table 1 (continued): Formulations of biodegradable polyester prepolymer resins in Examples 1-26 and Comparative Examples 1-3

[0090] Table 1 (continued): Formulations of biodegradable polyester prepolymer resins in Examples 1-26 and Comparative Examples 1-3

[0091]

Application Example 1

[0092] [Application Example 2] - [Application Example 26] The fully degradable tapes of Application Examples 2-26 were prepared according to the preparation method of Application Example 1, except that the biodegradable polyester prepolymer resins of Examples 2-26 were used to prepare the fully degradable tapes of Application Examples 2-26 respectively.

[0093] [Application Comparison Example 1] - [Application Comparison Example 2] The fully degradable tapes for Application Comparative Examples 1-2 were prepared according to the preparation method of Application Example 1, except that the biodegradable polyester prepolymer resins of Comparative Examples 1-2 were used to prepare the fully degradable tapes for Application Comparative Examples 1-2.

[0094] [Application Comparison Example 3] The fully degradable tape for Application Example 3 was prepared according to the preparation method of Application Example 1. The difference from Application Example 1 is that the biodegradable polyester prepolymer resin in step two of Application Example 3 could not be cured.

[0095] [Application Comparison Example 4] The fully degradable tape for Application Example 4 was prepared according to the preparation method of Application Example 1. The difference from Application Example 1 is that commercially available UV acrylic adhesive was used instead of biodegradable polyester prepolymer resin to prepare the tape.

[0096] The following performance tests were conducted on the fully degradable tapes provided in Application Examples 1-26 and Comparative Examples 1-3, as well as the UV acrylic adhesive provided in Comparative Example 4, to obtain the performance test results of the corresponding tapes. The performance tests are as follows (unless otherwise specified, all tests were conducted at 25°C): Viscosity at 120°C: The viscosity of unsaturated aliphatic polyester at 120°C was measured using a rotational viscometer.

[0097] Initial tack (ball number): The initial tack of the cured film adhesive is tested according to Method A (30° inclination) in GB / T4852-2002.

[0098] Holding power (hr): The holding time of the film adhesive on the cured side is tested according to Method A in GB / T4851-2014.

[0099] 180° peel strength (N / cm): Tested according to GB / T2792-2014.

[0100] Humidity and heat aging test: Cut 12 pieces of fully biodegradable tape, 30cm × 2.5cm each. Six pieces are reserved for later use, and the remaining six are fixed to a polyethylene terephthalate (PET) film with the tape, ensuring the adhesive layer does not contact the PET film. With the adhesive layer facing down, cover the PET film covered with the fully biodegradable tape above a water bath containing pure water, and secure the PET film to the water bath with tape. Set the water bath to 60℃ and heat for 6 hours, then remove the samples. The fully biodegradable tape treated with humidity and heat is then dried in a 30℃ forced-air oven for 5 hours, and its performance is tested.

[0101] Resistance to damp heat aging: Initial tack loss = Ball size before boiling - Ball size after boiling; The amount of holding power loss (hr) = holding time before boiling - holding time after boiling (wherein, if the holding time is greater than 24hr, it is calculated as 24hr). Peel strength loss (N / cm) = Peel strength before boiling - Peel strength after boiling

[0102] Industrial compostability: The industrial compostability of biodegradable polyester prepolymer resin, cured adhesive (cured biodegradable polyester prepolymer resin), and film was evaluated. The composting temperature was 58 ± 2°C, and other conditions were performed according to ASTM D5338-15. A relative biodegradation rate of 90% or higher within 6 months indicates industrial compostability; otherwise, it is considered non-compostable.

[0103] The test results for Application Examples 1-26 and Comparative Application Examples 1-4 are shown in Table 2.

[0104] Table 2: Performance test results of Application Examples 1-26 and Comparative Application Examples 1-4

[0105] Table 2 (continued): Performance test results of Application Examples 1-26 and Comparative Application Examples 1-4

[0106] Table 2 (continued): Performance test results of Application Examples 1-26 and Comparative Application Examples 1-4

[0107] Table 2 (continued): Performance test results of Application Examples 1-26 and Comparative Application Examples 1-4

[0108] Table 2 (continued): Performance test results of Application Examples 1-26 and Comparative Application Examples 1-4

[0109] Table 2 (continued): Performance test results of Application Examples 1-26 and Comparative Application Examples 1-4

[0110] As shown in Tables 1 and 2, and in conjunction with Application Examples 1-26 and Comparative Examples 1-4, the tapes prepared in Application Examples 1-26 exhibit both good adhesive properties and good hydrolysis resistance. Compared to Comparative Example 4, the biodegradable polyester prepolymer used in the tapes prepared in Application Examples 1-26 is biodegradable, while the acrylic acid used in Comparative Example 4 is not biodegradable, making them more environmentally friendly and playing a green and environmentally friendly role.

[0111] A comparison of Application Example 2 with Application Example 1 and Application Examples 3-26 shows that the addition of sebacic acid residues in Application Example 1 and Application Examples 3-26 effectively improved the adhesive properties of the tape.

[0112] A comparison of Application Examples 3-4 with Application Examples 1-2 and Application Examples 5-26 shows that a higher content of saturated aliphatic triol residues reduces the hydrolysis resistance of the tape, while a lower content of saturated aliphatic triol residues reduces the adhesive properties of the tape.

[0113] By comparing application examples 6 and 7 with application examples 1-5 and application examples 8-26, it can be seen that the residues of polycaprolactone polyol can effectively improve the hydrolysis resistance of the tape, but a large number of polycaprolactone polyol residues will reduce the adhesive performance of the tape.

[0114] By comparing Application Examples 19 and 20 with Application Examples 1-18 and Application Examples 21-26, it can be seen that when the residue content of unsaturated aliphatic dicarboxylic acids is low, the cohesive force is insufficient, resulting in poor adhesive strength of the tape. When the residue content of unsaturated aliphatic dicarboxylic acids is high, the adhesiveness of the tape decreases.

[0115] Comparing Application Examples 1-26 with Comparative Examples 1-3, it can be seen that Comparative Example 1 did not contain saturated aliphatic diacids, therefore its tape has poor hydrolysis resistance; Comparative Example 2 did not contain saturated aliphatic triols, therefore its tape has no adhesive properties; Comparative Example 3 did not contain unsaturated aliphatic diacids, therefore its biodegradable polyester prepolymer resin cannot be cured since it does not contain double bonds.

[0116] It should be noted that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. The directional terms "inner" and "outer" refer to inside or outside relative to the outline of each component itself. For example, if a device is inverted, a device described as "above" or "on top of other devices or structures" will later be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein are interpreted accordingly.

[0117] It should also be noted that the terms "one embodiment," "another embodiment," and "embodiment" used in this application refer to specific features, structures, or characteristics described in connection with that embodiment, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0118] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0119] It should also be noted that the above are merely preferred embodiments of this application and do not limit the scope of patent protection of this application. Any equivalent structural or procedural changes made using the content of this application's specification, or any direct or indirect application in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A biodegradable polyester prepolymer resin, characterized in that, Includes unsaturated aliphatic polyesters, said unsaturated aliphatic polyesters comprising the following components in molar proportions: 90-110 parts of saturated aliphatic dicarboxylic acid residues. 5-20 parts of unsaturated aliphatic dicarboxylic acid residues. 40-88 residues of saturated aliphatic triols 30-80 parts of saturated aliphatic diol residues.

2. The biodegradable polyester prepolymer resin according to claim 1, characterized in that, The unsaturated aliphatic polyester also includes residues of polycaprolactone polyol, and the molar fraction of the residues of the polycaprolactone polyol is 5 to 30 parts. The residues of the polycaprolactone polyol include one or both of the residues of polycaprolactone diol and polycaprolactone triol.

3. The biodegradable polyester prepolymer resin according to claim 2, characterized in that, The molecular weight of the residues in the polycaprolactone polyol is less than 1000 g / mol.

4. The biodegradable polyester prepolymer resin according to any one of claims 1 to 3, characterized in that, The residues of the saturated aliphatic dicarboxylic acid include one or more of the following: succinic acid residues, glutaric acid residues, adipic acid residues, octanoic acid residues, and sebacic acid residues.

5. The biodegradable polyester prepolymer resin according to any one of claims 1 to 3, characterized in that, The residues of the unsaturated aliphatic dicarboxylic acid include one or more of the following: residues of fumaric acid, maleic acid, and itaconic acid.

6. The biodegradable polyester prepolymer resin according to any one of claims 1 to 3, characterized in that, The residues of the saturated aliphatic triol are residues of glycerol.

7. The biodegradable polyester prepolymer resin according to any one of claims 1 to 3, characterized in that, The residues of the saturated aliphatic diol include one or more of the following: residues of propylene glycol, residues of butanediol, and residues of hexanediol.

8. The biodegradable polyester prepolymer resin according to any one of claims 1 to 3, characterized in that, The alkyd-to-acid ratio of the unsaturated aliphatic polyester is 1.0 to 1.

3.

9. A method for preparing the biodegradable polyester prepolymer resin according to any one of claims 1 to 8, characterized in that, Includes the following steps: According to the molar parts, saturated aliphatic dicarboxylic acid, unsaturated aliphatic dicarboxylic acid, saturated aliphatic triol and saturated aliphatic diol are added to the reactor, then the vacuum pump is turned on and the temperature is raised and stirred. When the reaction is completed, the vacuum pump is turned off to obtain unsaturated aliphatic polyester. The temperature is controlled to decrease, and then the additives are added to the reactor and stirred to obtain biodegradable polyester prepolymer resin.

10. The use of the biodegradable polyester prepolymer resin according to any one of claims 1 to 8 in adhesives and packaging materials.

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