Self-emulsifying bio-based polyester stabilized multi-class bio-based polymer aqueous emulsions, methods of making and applications thereof

Abstract

The application discloses a self-emulsifying bio-based polyester stabilized multi-class bio-based polymer aqueous emulsion and a preparation method and application thereof, and belongs to the technical field of bio-based polymer materials and aqueous resins. The application realizes efficient emulsification and interfacial compatibility of various hydrophobic bio-based film-forming polymers such as polyhydroxyaliphatic acid ester and polylactic acid by adopting a self-emulsifying bio-based polyester containing furan dicarboxylic acid and a rosin-based component to construct a double-interface synergistic stabilization mechanism. The emulsion prepared by the application has excellent storage stability and mechanical processing adaptability, significantly improves the water resistance, oil resistance and gas barrier performance of paper-based coatings, maintains a very high bio-based content and a very low volatile organic compound residue, and fully meets the safety standards of food contact grade materials. The preparation process precisely regulates the microstructure of the dispersed phase particles through phase inversion and high-pressure homogenization, and provides an ideal green coating solution for high-performance environment-friendly paper-based packaging.

Description

Technical Field

[0001] This invention belongs to the field of bio-based polymer materials and aqueous resin technology, specifically relating to self-emulsifying bio-based polyester-stabilized aqueous emulsions of various bio-based polymers, their preparation methods, and applications. Background Technology

[0002] Waterborne coatings, adhesives, inks, and packaging coating systems are becoming important directions in the materials industry due to low volatile organic compounds (VOCs), safe application, and regulatory requirements. At the same time, the rapid growth in demand for bio-based alternatives, sustainable supply chains, and environmentally friendly materials is driving the expansion of hydrophobic bio-based polymers such as polyhydroxyalkanoates (PHA), polylactic acid (PLA), polybutylene succinate (PBS), polybutylene succinate-butylene adipate copolyester (PBSA), polycaprolactone (PCL), polyethylene furanate (PEF), and other furanate dicarboxylic acid (FDCA)-based polyesters from thermoplastic processing to waterborne applications.

[0003] In the prior art, the main routes for achieving the aqueous transformation of the aforementioned hydrophobic bio-based polymers are as follows: The external emulsifier and protective colloid route: Biodegradable polyesters are dispersed in a melt or solvent system into an aqueous phase using protective colloids such as polyvinyl alcohol (PVA) or anionic and nonionic surfactants to form an aqueous dispersion. For example, US6716911B2 discloses an aqueous dispersion of biodegradable polyester or PLA materials and its preparation process; CN120865687A discloses an aqueous dispersion of PHA stabilized by solid particles and natural surfactants and its preparation method. The end-group and chain segment modification and reactive emulsification route: Hydrophilicity is improved by grafting with anhydrides, activating end groups, or introducing reactive emulsifiers, followed by phase inversion dispersion to obtain an aqueous dispersion. For example, CN120944505A discloses a technical route for preparing PHA aqueous adhesives by activating PHA end groups with bio-based cyclic anhydrides and combining them with reactive emulsifiers. Aqueous Rosin-Based Resins: Rosin and its derivatives can be saponified or prepared into rosin esters to form aqueous dispersions with modified resins, which are widely used in paper sizing, tackification, or aqueous coatings. Synergistic Route of Acid-Modified Resins and Tackifying Resins in Aqueous Dispersions: For example, CN103619944B discloses an aqueous dispersion containing acid-modified resins and tackifying components for use in adhesive applications.

[0004] The above-mentioned approaches still have common shortcomings in engineering applications:

[0005] Firstly, the addition of low-molecular-weight surfactants can easily lead to problems such as foaming, migration, odor, water whitening, salt resistance and freeze-thaw sensitivity, and weaken the goal of "high bio-based or pure bio-based".

[0006] Secondly, end-group modification or grafting routes increase reaction steps and costs, and bring batch-to-batch fluctuations and side reaction risks;

[0007] Third, the waterborne formulation of rosin-based resins mainly focuses on rosin bulk dispersion or rosin-modified resin coatings, which makes it difficult to provide unified interfacial stability and compatibility for multiple types of hydrophobic bio-based film-forming polymers at the same time. In particular, there is still room for improvement in terms of high solids content, long shelf life, and barrier and water resistance.

[0008] Fourth, in addition to service life barrier, water and oil resistance, paper-based packaging coating must also meet the comprehensive requirements of coating line and downstream processing.

[0009] Fifth, paper-based packaging must also consider compliance risks related to recyclability, repulping, and migration during the end-of-life (EOL) stage.

[0010] Therefore, there is a need for a waterborne platform technology that, under high bio-based constraints, can provide scalable and tunable improvements in interface stability, compatibility, water resistance, and barrier properties for various hydrophobic bio-based film-forming polymers, while minimizing dependence on added low-molecular-weight surfactants and organic solvents, to support the industrialization of paper and paperboard barrier coatings and downstream processing of paper-based packaging. Summary of the Invention

[0011] The purpose of this invention is to overcome the shortcomings of the prior art and provide self-emulsifying bio-based polyester-stabilized aqueous emulsions of various bio-based polymers, their preparation methods, and applications.

[0012] To achieve the above objectives, the present invention provides the following technical solution:

[0013] This invention provides a self-emulsifying bio-based polyester-stabilized aqueous emulsion of various bio-based polymers, with water as the continuous phase and containing dispersed phase particles. The dispersed phase particles comprise a hydrophobic bio-based film-forming polymer and a self-emulsifying bio-based polyester, wherein the hydrophobic bio-based film-forming polymer and the self-emulsifying bio-based polyester are different polymer components. The self-emulsifying bio-based polyester is a copolyester containing carboxyl hydrophilic groups or their salts, obtained by polycondensation of FDCA, aliphatic diacids, diols, and carboxyl-containing functional monomers. The hydrophilic groups, after neutralization, exist at least partially in salt form and form a continuous or semi-continuous stable layer at the interface of the dispersed phase particles, thereby achieving interfacial stabilization and compatibility with the hydrophobic bio-based film-forming polymer. The acid value of the self-emulsifying bio-based polyester is 20–40 mg KOH / g, specifically 20 mg KOH / g, 21 mg KOH / g, 22 mg KOH / g, 23 mg KOH / g, 24 mg KOH / g, 25 mg KOH / g, and 26 mg KOH / g. KOH / g, 28mg KOH / g, 30mg KOH / g, 32mg KOH / g, 34mg KOH / g, 35mg KOH / g, 36mg KOH / g, 38mg KOH / g, 39mg KOH / g, or 40mg KOH / g, with a number-average molecular weight (Mn) of 5×10⁻⁶. 4 ~1×10 5 Specifically, Mn can be 5.0 × 10 4 5.2×10 4 5.5×10 4 5.8×10 4 6.0×10 4 6.5×10 4 7.0×10 4 7.2×10 4 7.5×10 4 8.0×10 4 8.5×10 4 9.0×10 4 9.5×10 4 Or 1.0×10 5 The aqueous emulsion has a solid content of 35-60 wt%, specifically 35 wt%, 35.5 wt%, 36 wt%, 38 wt%, 40 wt%, 40.1 wt%, 40.2 wt%, 40.3 wt%, 42 wt%, 45 wt%, 45.1 wt%, 45.2 wt%, 45.3 wt%, 45.4 wt%, 48 wt%, 50 wt%, 50.1 wt%, 50.2 wt%, 52 wt%, 55 wt%, 55.2 wt%, 58 wt%, 59 wt%, or 60 wt%. 50 The specific D is 80-350nm.50 The wavelengths can be 80nm, 85nm, 90nm, 95nm, 100nm, 110nm, 120nm, 130nm, 145nm, 150nm, 160nm, 175nm, 178nm, 180nm, 185nm, 190nm, 195nm, 200nm, 205nm, 210nm, 220nm, 230nm, 250nm, 280nm, 300nm, 310nm, 320nm, 330nm, 340nm, 345nm, or 350nm, with a pH of 6.5–9.0. Specific pH values ​​can be 6.5, 6.6, 6.8, 7.0, 7.2, 7.5, 7.8, 7.9, 8.0, 8.1, 8.2, 8.3, 8.4, 8.5, 8.8, 8.9, or 9.0.

[0014] The hydrophobic bio-based film-forming polymer is selected from one or more of the following: PHA and its copolymers or blends, wherein the PHA includes poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-3-hydroxyhexanoate) (PHBH), poly(3-hydroxybutyrate-4-hydroxybutyrate) (P34HB), poly(3-hydroxybutyrate-3-hydroxyvalerate) (PHBV), and medium- and long-chain PHA, wherein the medium- and long-chain PHA includes poly(3-hydroxyhexanoate), poly(3-hydroxyheptanoate), poly(3-hydroxyoctanoate), poly(3-hydroxynonanoate), poly(3-hydroxydecanoate), poly(3-hydroxyundecanoate), poly(3-hydroxydodecanate), poly(3-hydroxytetrate), and poly(3-hydroxytetradecanoate); and polyesters, namely PLA, obtained by polymerization of lactic acid or lactide monomers and their copolymers or blends, wherein the comonomers of the copolymers include glycolic acid or glycolide, ε-caprolactone, δ-valerate, and p-dioxane. Ketones, trimethylene carbonate, or combinations thereof; aliphatic polyesters and their copolymers or blends obtained by polycondensation of diacids and diols, wherein the diacid is selected from succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, itaconic acid, fumaric acid, maleic acid, or combinations thereof, and the diol is selected from ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentanediol, isosorbide, or combinations thereof, and specific aliphatic polyesters include PBS, PBSA, and PCL; FDCA-based polyesters and their copolyesters or blends obtained by polycondensation of FDCA or its esters with diols, wherein the diol is selected from ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, isosorbide, or combinations thereof, and specific FDCA-based polyesters include PEF; and blends of any combination thereof.

[0015] The self-emulsifying bio-based polyester is a copolyester obtained by polycondensation of a diacid, a diol, and a carboxyl-containing functional monomer. The diacid includes FDCA and aliphatic diacids. The aliphatic diacid is selected from one or more of succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, itaconic acid, fumaric acid, and maleic acid. The diol is selected from one or more of ethylene glycol, 1,4-butanediol, 1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol, and isosorbide. The functional monomer is selected from one or more of citric acid, malic acid, glycolic acid, and lactic acid.

[0016] The content of furanyl dicarboxylic acid is 5-40 mol based on the molar amount of dicarboxylic acid, and the specific content can be 5 mol%, 8 mol%, 10 mol%, 15 mol%, 20 mol%, 25 mol%, 30 mol%, 35 mol%, 38 mol%, or 40 mol. The total content of the functional monomers is 5-15 mol based on the total molar amount of all monomers participating in the polycondensation reaction, and the specific content can be 5 mol%, 6 mol%, 7 mol%, 8 mol%, 9 mol%, 10 mol%, 11 mol%, 12 mol%, 13 mol%, 14 mol%, or 15 mol.

[0017] The mass ratio of the hydrophobic bio-based film-forming polymer and the self-emulsifying bio-based polyester, based on the total solid content, is 95:5 to 30:70. Specific mass ratios can be 95:5, 90:10, 85:15, 80:20, 75:25, 70:30, 65:35, 60:40, 50:50, 40:60, or 30:70. The degree of neutralization of the carboxyl hydrophilic groups, based on the molar amount of carboxyl hydrophilic groups in the self-emulsifying bio-based polyester, is 20% to 80%. Specific neutralization degrees can be 20%, 25%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, or 80%. The neutralizing agent used for neutralization is selected from one or more of L-arginine, choline hydroxide, sodium bicarbonate, and potassium bicarbonate.

[0018] The aqueous emulsion further comprises a rosin-based functional resin component, which is selected from rosin, rosin acid, rosin salt, rosin ester, hydrogenated rosin, disproportionated rosin, polymerized rosin, maleic rosin, fumaric rosin, dimer rosin acid, and combinations thereof. When the rosin-based functional resin component is a rosin ester, the softening point of the rosin ester is 80-130°C, specifically 80°C, 82°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 120°C, 125°C, or 130°C. Based on the total solids of the emulsion, the content of the rosin-based functional resin component is 0.5-20 wt%, specifically 0.5 wt%, 0.8 wt%, 1 wt%, 2 wt%, 5 wt%, 8 wt%, 10 wt%, 12 wt%, 15 wt%, 18 wt%, 19 wt%, or 20 wt%.

[0019] The self-emulsifying bio-based polyester further comprises a rosin-based structural unit derived from rosin acid, wherein the rosin acid is used as a chain end-capping unit or a hydrophobic compatibility unit. The amount of the rosin-based structural unit introduced is 1 to 10 wt%, and the specific amount can be 1 wt%, 1.5 wt%, 2 wt%, 3 wt%, 4 wt%, 5 wt%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 9.5 wt%, or 10 wt%, based on the solids of the self-emulsifying bio-based polyester.

[0020] The aqueous emulsion or aqueous dispersion of the present invention further comprises a protective colloid, a rheology modifier, or a Pickering particle stabilizer, wherein the protective colloid or rheology modifier is selected from one or more of cellulose and its derivatives, starch and its derivatives, xanthan gum, pectin, gum arabic, alginate, lignin and its derivatives, and PVA, and the Pickering particle stabilizer is selected from one or more of nanocellulose crystals, nanocellulose fibers, lignin nanoparticles, starch nanoparticles, chitosan nanoparticles, silica nanoparticles, montmorillonite, and kaolin.

[0021] The aqueous emulsion has an absolute Zeta potential value ≥30mV, specifically 30mV, 31mV, 32mV, 34mV, 35mV, 36mV, 37mV, 38mV, 39mV, 40mV, 41mV, 42mV, 45mV, or 48mV, and exhibits the following storage stability: after being sealed and left to stand at 25±2℃ for 3 months, the height of the supernatant layer accounts for ≤2% of the total sample height, and the height of the sediment layer accounts for ≤5% of the total sample height; it can be restored to homogeneity after being shaken 10 times by hand, and D 50 The rate of change is ≤10%.

[0022] The present invention also provides a method for preparing the above-mentioned aqueous emulsion, comprising the following steps:

[0023] Step 1. Provide hydrophobic bio-based film-forming polymer, self-emulsifying bio-based polyester, neutralizer, and rosin-based functional resin components and additives as needed;

[0024] Step 2. Heat the hydrophobic bio-based film-forming polymer and the self-emulsifying bio-based polyester until softened or melted and mix them; when the rosin-based functional resin component is provided in Step 1, add the rosin-based functional resin component and mix it with the molten system to obtain a molten composite phase;

[0025] Step 3. Add a neutralizing agent to the molten composite phase obtained in Step 2 to make the degree of neutralization of the carboxyl hydrophilic groups of the self-emulsifying bio-based polyester 20-80%, thereby obtaining a neutralized molten composite phase;

[0026] Step 4. Under shear dispersion conditions, water is gradually added to the neutralized molten composite phase obtained in Step 3 to cause the system to undergo phase inversion and form an oil / water type aqueous dispersion with water as the continuous phase; the phase inversion endpoint is defined as the system changing from a viscous molten state to a free-flowing milky white continuous aqueous phase, and no oil droplets appearing after dilution with deionized water. The pre-dispersion is then obtained.

[0027] Step 5. The pre-dispersion obtained in Step 4 is subjected to high-pressure homogenization to refine the particle size, thereby obtaining the median particle size D. 50 It is an aqueous emulsion or aqueous dispersion with a wavelength of 80–350 nm;

[0028] Step 6. Cool and adjust the pH to 6.5–9.0 to obtain the finished product;

[0029] The melt bonding temperature is 95–220℃, specifically 95℃, 100℃, 110℃, 120℃, 130℃, 140℃, 150℃, 160℃, 170℃, 180℃, 190℃, 200℃, 210℃, or 220℃. The shearing speed is 4000–20000 rpm, specifically 4000 rpm, 5000 rpm, 6000 rpm, 8000 rpm, or 10000 rpm. The homogenization pressure is 20-120 MPa, with specific values ​​of 20 MPa, 25 MPa, 30 MPa, 35 MPa, 40 MPa, 45 MPa, 50 MPa, 60 MPa, 70 MPa, 80 MPa, 90 MPa, 100 MPa, 110 MPa, or 120 MPa.

[0030] The present invention also provides the application of the aqueous emulsion for paper barrier coatings and paper-based packaging coatings, wherein the barrier coating is used to reduce the permeation of paper to water, grease, water vapor and oxygen.

[0031] The total amount of added low-molecular-weight surfactants, based on the total solids of the emulsion, is ≤0.1wt%, specifically 0wt%, 0.01wt%, 0.02wt%, 0.03wt%, 0.05wt%, 0.08wt%, or 0.10wt%; the added low-molecular-weight surfactants include alkyl sulfate anionic surfactants, alkylbenzene sulfonate anionic surfactants, and optionally nonionic low-molecular-weight surfactants; wherein, the combination of alkyl sulfate anionic surfactants and alkylbenzene sulfonate anionic surfactants... The content of organic solvent in the aqueous emulsion is ≤0.5wt%, specifically 0wt%, 0.01wt%, 0.02wt%, 0.03wt%, 0.04wt%, or 0.05wt% based on the weight of the finished product. Specifically, the content of organic solvent in the aqueous emulsion is ≤0.5wt%, specifically 0wt%, 0.01wt%, 0.05wt%, 0.10wt%, 0.20wt%, 0.30wt%, or 0.50wt% based on the weight of the finished product. The bio-based carbon content of the emulsion solids and the free dry film formed therefrom after drying to constant weight is 80.0% to 95.0%, as determined by GB / T 39715.2-2021.

[0032] Compared with the prior art, the following significant advantages can be obtained by using the present invention:

[0033] Excellent barrier properties and film-forming properties: Through the tight combination of self-emulsifying polyester and film-forming polymer and the hydrophobic enhancement of rosin-based components, the emulsion can form a dense and smooth coating on the paper surface, significantly reducing the Cobb water absorption value of the paper, improving the KIT oil resistance level, and greatly enhancing the barrier efficiency against water vapor and oxygen. The coating has a smooth appearance without pinholes and good flexibility, meeting the high-performance requirements of paper-based packaging.

[0034] High bio-based content and safety compliance: The system of this invention greatly reduces the dependence on external low molecular weight surfactants (such as SDS) and organic solvents. The organic solvent residue and anionic surfactant content are extremely low, which not only meets the safety standards for food contact materials, but also maintains the high bio-based properties of the system, reduces VOC emissions, and has significant environmental friendliness.

[0035] Excellent machinability: The resulting emulsion exhibits excellent stability under harsh mechanical shearing conditions such as high-speed stirring and pumping circulation, with no demulsification, clumping or pump blockage. The filtration residue is extremely low, which can meet the continuous operation requirements of industrial high-speed coating machines and has good prospects for engineering applications. Attached Figure Description

[0036] Figure 1 The microstructure of the coating formed by coating a paper substrate with a self-emulsifying bio-based polyester-stabilized aqueous emulsion of various bio-based polymers as described in this invention and then drying it.

[0037] In the figure, 1-paper; 2-continuous phase; 3-dispersed phase particles; 4-hydrophobic bio-based film-forming polymer; 5-nanocellulose crystals; 6-self-emulsifying bio-based polyester; 7-silica nanoparticles; 8-carboxyl hydrophilic groups; 9-rosin acid structural units. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention. Unless otherwise stated, the raw materials used in this embodiment are commercially available industrial products or can be prepared by conventional methods. Unless otherwise specified, performance testing methods are performed according to the standards described in the invention summary section.

[0039] Figure 1 This is a schematic diagram of the microstructure of a dense composite coating formed by coating a self-emulsifying bio-based polyester stabilized bio-based polymer aqueous emulsion coating system onto a fiber surface and drying and curing. The structure includes a support substrate paper 1, the upper surface of which is covered with a continuous phase 2, obtained by drying the aqueous emulsion system, which is gray in color and has a finely etched texture. The continuous phase 2 constitutes the main matrix layer of the coating, and its internal dispersed phase consists of spherical dispersed phase particles 3 with a white shell and a dark gray core. A multi-scale composite stable structure is constructed at the interface. A magnified view further visually shows that the dispersed phase particles 3 contain a hydrophobic bio-based film-forming polymer 4 with a completely dark core, nanocellulose crystals 5 with a gray continuous interface layer surrounding the core hydrophobic bio-based film-forming polymer, and a self-emulsifying bio-based polyester 6 with a white continuous outer shell layer located on the outermost side of the nanocellulose crystals 5. Furthermore, smaller, single gray spherical particles of synergistically stabilized silica nanoparticles 7 are dispersed in the gaps between the dispersed phase particles 3. The schematic diagram at the bottom right visually illustrates the specific chemical groups and molecular structures derived from different components contained in the coating system, including straight lines representing the molecular backbone and groups labeled with carboxyl groups (-COO). - The molecular chain segment of carboxyl hydrophilic group 8, composed of a complex sequence of symbols such as siloxane, R1, R2, and -OH, and the organic molecular rosin acid structural unit 9 representing specific interface and functional stereostructural details, indicate that each active ingredient constructs an overall network with dense barrier function through multi-scale interface stabilization.

[0040] Main reagents and raw materials:

[0041] Table 1. Information on Main Reagents and Raw Materials:

[0042]

[0043] Main analytical and testing instruments:

[0044] Table 2. Information on Main Analytical and Testing Instruments:

[0045]

[0046] Main testing standards:

[0047] Self-emulsifying bio-based polyester acid value (mg KOH / g): GB / T 2895-2008;

[0048] Number-average molecular weight (Mn) / molecular weight distribution of self-emulsifying bio-based polyesters (size exclusion chromatography (SEC), THF as mobile phase): GB / T 21863-2008;

[0049] Emulsion solids content (non-volatile matter): GB / T 1725-2007;

[0050] Cobb Paper / Paperboard 60 Water absorption: GB / T 1540-2002;

[0051] Rosin ester softening point: GB / T 9284.1-2015;

[0052] KIT oil repellency rating: determined according to TAPPI T 559 cm-22, as an auxiliary indicator of surface oil repellency;

[0053] Water vapor transmission rate (WVTR): Refer to GB / T 26253-2010;

[0054] Oxygen permeability (OTR): Refer to GB / T 19789-2021;

[0055] Anionic surfactants (alkyl sulfates / alkylbenzene sulfonates): GB / T 5173-2018;

[0056] Solvent residue in food contact materials and articles: Refer to the headspace GC-MS test conditions in GB 31604.60-2024;

[0057] VOC content of coating / resin system (gas chromatography): GB / T 23986.2-2023.

[0058] Emulsion solids / free-drying membrane bio-based carbon content: GB / T 39715.2-2021.

[0059] Preparation of homemade rosin soap (C3): Weigh 100.0g of rosin acid and add it to a three-necked flask equipped with a mechanical stirrer. Melt at 90℃ and keep warm. Separately, prepare a 10.0wt% sodium bicarbonate aqueous solution. Calculate the theoretical neutralization amount based on the acid value of rosin acid and add it dropwise until the pH of the system reaches 8.5. Maintain stirring at 90℃ for 60min. After the reaction, dehydrate under reduced pressure to a solid content of 90.0wt%. Continue dehydration at 60℃ and -0.08MPa until the water content is ≤1.0wt%. After cooling, seal and store to obtain rosin soap C3.

[0060] Preparation of self-made high softening point modified rosin ester (C5): 100.0 g of rosin acid and 5.0 g of maleic anhydride were weighed and added to a four-necked reactor. Under nitrogen protection, the temperature was raised to 200℃ and reacted for 120 min to obtain maleicized rosin acid intermediate. Subsequently, 12.0 g of pentaerythritol and 0.10 g of tetrabutyl titanate were added, and the temperature was raised to 260℃ for esterification reaction for 240 min, while continuously removing by-product water. After the reaction was completed, the material was discharged and cooled to obtain high softening point modified rosin ester C5 with a softening point of 130℃.

[0061] Preparation of homemade low softening point rosin esters (C6, C7): 100.0g of rosin acid and 8.5g of glycerol were weighed and added to a four-necked reactor. Under nitrogen protection, the temperature was raised to 220℃ for esterification reaction for 180min, and by-product water was continuously removed to obtain low softening point rosin ester C6 with a softening point of 80℃. In the same apparatus, the amount of glycerol was adjusted to 9.5g and the reaction time was controlled to 140min to obtain low softening point rosin ester C7 with a softening point of 75℃.

[0062] Example:

[0063] Unless otherwise stated, the mol% of the dicarboxylic acid composition in each embodiment is calculated based on the total molar amount of the dicarboxylic acid, the mol% of the diol composition is calculated based on the total molar amount of the diol, and the mol% of the functional monomer is calculated based on the total molar amount of all monomers participating in the polycondensation reaction; the amount of each monomer added is converted according to the molar percentages and balanced according to the equivalent amounts of carboxyl and hydroxyl groups.

[0064] Example 1: Preparation of BioTen 1031 aqueous emulsion (PHBV).

[0065] Step 1. Preparation of self-emulsifying bio-based copolyester B1: In a 2L four-necked reactor under nitrogen protection, add diacid components (20 mol% FDCA, 30 mol% succinic acid, 50 mol% adipic acid by total molar weight) and diol components (70 mol% 1,4-butanediol, 20 mol% 1,3-propanediol, 10 mol% isosorbide by total molar weight). Add functional monomers (12 mol% total molar weight of all monomers participating in the polycondensation reaction, including 2 mol% citric acid and 10 mol% glycolic acid). Add tetrabutyl titanate as a catalyst at 0.1 wt% of the total monomer mass. After esterification at 180℃ for 4 hours, raise the temperature to 230℃ and perform vacuum polycondensation for 3 hours under a vacuum of ≤200 Pa. After the reaction, discharge the product to obtain self-emulsifying bio-based copolyester B1. The acid value of the copolyester B1, as determined by GB / T 2895-2008, was 25 mg KOH / g, and the Mn, as determined by GB / T 21863-2008, was 7.2 × 10⁻⁶. 4 .

[0066] Step 2. Preparation of aqueous emulsion: Hydrophobic bio-based film-forming polymer PHBV resin and copolyester B1 obtained in Step 1 are added to a closed melt mixing container at a mass ratio of 70:30. The mixture is melt-mixed at 180°C for 20 minutes until homogeneous. The melt system is cooled and maintained at 95°C. L-arginine is pre-prepared into a 20wt% aqueous solution as a neutralizing agent. The amount of neutralizing agent added is calculated based on 70% of the molar amount of the hydrophilic carboxyl groups in copolyester B1. The mixture is stirred at 300 rpm for 10 minutes to obtain a neutralized melt composite phase. The water introduced by the neutralizing agent aqueous solution is included in the total water volume of the system. Subsequently, deionized water is added in 10 equal portions under shear conditions at 8000 rpm, each addition being 10% of the remaining deionized water volume. The remaining deionized water volume is determined by back-calculating the target solid content of 45.2wt% after deducting the water introduced by the neutralizing agent aqueous solution. After phase inversion occurs and a pre-dispersion with water as the continuous phase is formed, shearing continues for 5 minutes. The pre-dispersion was homogenized twice under high pressure at 40 MPa, cooled to 25 °C, and then added dropwise with 10 wt% L-arginine aqueous solution or 10 wt% sodium bicarbonate aqueous solution while stirring until pH=8.2, resulting in an aqueous emulsion of BioTen 1031 with a solid content of 45.2 wt%.

[0067] Example 2: Preparation of PLA aqueous emulsion.

[0068] Step 1. Preparation of self-emulsifying bio-based copolyester B2: Following the polyester synthesis process conditions of Step 1 in Example 1, monomers were added to a 2L four-necked reactor under nitrogen protection. The monomers included 35 mol% FDCA, 25 mol% succinic acid, and 40 mol% adipic acid; 80 mol% 1,4-butanediol and 20 mol% 1,3-propanediol; and a total of 13 mol% functional monomers (3 mol% malic acid and 10 mol% lactic acid) were used. After the reaction, the self-emulsifying bio-based copolyester B2 was obtained. The acid value of copolyester B2, as determined by GB / T 2895-2008, was 35 mg KOH / g, and the Mn, as determined by GB / T 21863-2008, was 5.5 × 10⁻⁶. 4 .

[0069] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the remaining melt mixing and holding time, stepwise water addition method, shear dispersion speed and time, reverse rotation sequence, number of high-pressure homogenization cycles, and post-cooling pH adjustment are all the same as in Step 2 of Example 1. The hydrophobic bio-based film-forming polymer PLA resin and the copolyester B2 obtained in Step 1 were mixed in a mass ratio of 80:20. The neutralizing agent was replaced with choline hydroxide, with a neutralization degree of 65%. The melt temperature was adjusted to 190°C. The pre-dispersion was homogenized twice under high pressure at 60 MPa. After cooling, the final pH of the system was adjusted to 8.0 to obtain an aqueous PLA emulsion with a target solid content of 40.1 wt%.

[0070] Example 3: Preparation of BioTen 1032 aqueous emulsion (P34HB).

[0071] Step 1. Preparation of self-emulsifying bio-based copolyester B3: Following the polyester synthesis process conditions of Step 1 in Example 1, monomers were added to a 2L four-necked reactor under nitrogen protection. The monomers included 5 mol% FDCA, 35 mol% succinic acid, and 60 mol% adipic acid; 60 mol% 1,4-butanediol, 20 mol% 1,3-propanediol, and 20 mol% isosorbide. Based on the total molar amount of all monomers participating in the polycondensation reaction, the total amount of functional monomers was 7 mol%, including 2 mol% citric acid and 5 mol% glycolic acid. After the reaction, the self-emulsifying bio-based copolyester B3 was obtained. The acid value of the copolyester B3, as determined by GB / T 2895-2008, was 22 mg KOH / g, and the Mn, as determined by GB / T 21863-2008, was 9.0 × 10⁻⁶. 4 .

[0072] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the remaining melt mixing and holding time, stepwise water addition method, shear dispersion speed and time, reverse rotation sequence, number of high-pressure homogenization cycles, and post-cooling pH adjustment are all the same as in Step 2 of Example 1. The hydrophobic bio-based film-forming polymer P34HB resin and the copolyester B3 obtained in Step 1 were mixed in a mass ratio of 75:25. The neutralizing agent was replaced with potassium bicarbonate, with a neutralization degree of 60%. The melt temperature was adjusted to 160°C. The pre-dispersion was homogenized twice under high pressure at 30 MPa. After cooling, the pH of the system was finally adjusted to 7.9 to obtain a BioTen1032 aqueous emulsion with a target solid content of 40.3 wt%.

[0073] Example 4: Preparation of PEF aqueous emulsion.

[0074] Step 1. Provide the copolyester B1 obtained in Step 1 of Example 1.

[0075] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the remaining melt mixing and holding time, stepwise water addition method, shear dispersion speed and time, reverse rotation sequence, number of high-pressure homogenization cycles, and post-cooling pH adjustment are all the same as in Step 2 of Example 1. The hydrophobic bio-based film-forming polymer PEF resin and the copolyester B1 provided in Step 1 are mixed in a mass ratio of 60:40. The neutralizing agent is replaced with sodium bicarbonate, with a neutralization degree of 70%. The melt temperature is adjusted to 220°C. The pre-dispersion is homogenized twice under high pressure at 80 MPa. After cooling, the final pH of the system is adjusted to 8.1 to obtain a PEF aqueous emulsion with a target solid content of 35.5 wt%.

[0076] Example 5: Preparation of aqueous emulsion of PBS.

[0077] Step 1. Provide the copolyester B3 obtained in Step 1 of Example 3.

[0078] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the remaining melt mixing and holding time, stepwise water addition method, shear dispersion speed and time, reverse rotation sequence, number of high-pressure homogenization cycles, and post-cooling pH adjustment are all the same as in Step 2 of Example 1. The hydrophobic bio-based film-forming polymer PBS resin and the copolyester B3 provided in Step 1 were mixed in a mass ratio of 70:30. The neutralizing agent was replaced with sodium bicarbonate, with a neutralization degree of 50%. The melt temperature was adjusted to 140°C. The pre-dispersion was homogenized twice under high pressure at 20 MPa. After cooling, the final pH of the system was adjusted to 7.8 to obtain a PBS aqueous emulsion with a target solid content of 50.2 wt%.

[0079] Example 6: Preparation of PBSA aqueous emulsion.

[0080] Step 1. Provide the copolyester B1 obtained in Step 1 of Example 1.

[0081] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the remaining melt mixing and holding time, stepwise water addition method, shear dispersion speed and time, reverse rotation sequence, number of high-pressure homogenization cycles, and post-cooling pH adjustment are all the same as in Step 2 of Example 1. The hydrophobic bio-based film-forming polymer PBSA resin and the copolyester B1 provided in Step 1 were mixed in a mass ratio of 60:40. The neutralizing agent was replaced with choline hydroxide, with a neutralization degree of 70%. The melt temperature was adjusted to 130°C. The pre-dispersion was homogenized twice under high pressure at 30 MPa. After cooling, the final pH of the system was adjusted to 8.2 to obtain an aqueous PBSA emulsion with a target solid content of 40.0 wt%.

[0082] Example 7: Preparation of BioTen 1031 aqueous emulsion (PHBV / rosin modified).

[0083] Step 1. Provide the copolyester B1 obtained in Step 1 of Example 1.

[0084] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the types and degrees of neutralization of the neutralizing agent, the melt mixing and holding time, the stepwise water addition method, the shear dispersion speed and time, the reverse rotation sequence, the number of high-pressure homogenization cycles, and the post-cooling pH adjustment are all the same as in Step 2 of Example 1. The hydrophobic bio-based film-forming polymer PHBV resin and the copolyester B1 provided in Step 1 were used, and glycerol rosin ester C1 was added additionally during the melt mixing stage. The mass ratio of polymer:polyester:rosin was 65:25:10. The melting temperature was 180°C. The pre-dispersion was homogenized twice under high pressure at 40 MPa. After cooling, the pH of the system was finally adjusted to 8.3 to obtain a BioTen1031 aqueous emulsion (PHBV / rosin modified) with a target solid content of 45.1 wt%.

[0085] Example 8: Preparation of PLA aqueous emulsion (rosin modified).

[0086] Step 1. Preparation of self-emulsifying bio-based polyester B4: The monomer composition of B4 is the same as that of copolyester B1, but rosin acid is added as a chain end-capping unit in the later stage of polycondensation. The amount of rosin acid added is 5wt%. Based on the solids of the self-emulsifying bio-based polyester obtained by polycondensation, the measured acid value is 28 mg KOH / g, and Mn is 6.5 × 10⁻⁶. 4 .

[0087] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the types and degrees of neutralization of the neutralizing agent, the melting and mixing holding time, the stepwise water addition method, the shear dispersion speed and time, the reverse rotation operation sequence, the number of high-pressure homogenization cycles, and the post-cooling pH adjustment operation are all the same as in Step 2 of Example 2. Take the hydrophobic bio-based film-forming polymer PLA resin and the copolyester B4 obtained in Step 1, and add rosin soap C3 during the melt mixing stage. The mass ratio of polymer:polyester:rosin is 75:24:1. The melting temperature is adjusted to 180℃. The pre-dispersion is homogenized twice under high pressure at 50MPa. After cooling, the final pH of the system is adjusted to 8.1, and the system is de-vaporized under reduced pressure at 40℃ and -0.08MPa for 30 min to remove trace organic volatiles, obtaining a PLA aqueous emulsion (rosin modified) with a target solid content of 45.3wt%.

[0088] Example 9: Preparation of BioTen 1031 aqueous emulsion (PHBV / CNC enhanced).

[0089] Step 1. Provide the copolyester B1 obtained in Step 1 of Example 1.

[0090] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the mass ratio of polymer to polyester, the type and degree of neutralization, the melt mixing and holding time, the stepwise water addition method, the shear dispersion speed and time, the phase inversion operation sequence, and the post-cooling pH adjustment operation are all the same as in Step 2 of Example 1. The hydrophobic bio-based film-forming polymer PHBV resin and the copolyester B1 provided in Step 1 are taken at a mass ratio of 70:30. During the phase inversion emulsification water addition process, after the third equal volume water addition is completed, a nanocellulose crystal aqueous dispersion (10 wt%) is added, making the CNC dry basis ratio 0.5 wt% based on the total emulsion solids. After addition, shearing at 8000 rpm for 3 minutes is continued, followed by the subsequent water addition steps. The pre-dispersion is homogenized twice under high pressure at 50 MPa. After cooling, the final pH of the system is adjusted to 8.0 to obtain a BioTen1031 aqueous emulsion (PHBV / CNC enhanced) with a target solids content of 45.0 wt%.

[0091] Example 10: Preparation of BioTen 1031 aqueous emulsion (PHBV / silica stabilized).

[0092] Step 1. Provide the copolyester B1 obtained in Step 1 of Example 1.

[0093] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the mass ratio of polymer to polyester, the type and degree of neutralization, the melt mixing and holding time, the stepwise water addition method, the shear dispersion speed and time, the phase inversion operation sequence, and the post-cooling pH adjustment operation are all the same as in Step 2 of Example 1. The hydrophobic bio-based film-forming polymer PHBV resin and the copolyester B1 provided in Step 1 are taken at a mass ratio of 70:30. During the phase inversion emulsification water addition process, after the third equal-volume water addition is completed, silica nano-dispersion (50 wt%) is added, making the silica dry basis ratio 0.5 wt% based on the total emulsion solids. After addition, shearing at 8000 rpm for 3 minutes is continued, followed by the subsequent water addition steps. The pre-dispersion is homogenized twice under high pressure at 50 MPa. After cooling, the final pH of the system is adjusted to 8.2 to obtain a BioTen1031 aqueous emulsion (PHBV / silica stabilized) with a target solid content of 45.2 wt%.

[0094] Example 11: Preparation of BioTen 1031 aqueous emulsion (PHBV / high acid value polyester).

[0095] Step 1. Preparation of self-emulsifying bio-based polyester B7: Following the process in Step 1 of Example 1, the dicarboxylic acid was 40 mol% FDCA, 20 mol% succinic acid, and 40 mol% adipic acid; the diols were 60 mol% 1,4-butanediol and 40 mol% 1,3-propanediol. Based on the total molar amount of all monomers participating in the polycondensation reaction, the total amount of functional monomers was 15 mol%, including 5 mol% citric acid and 10 mol% glycolic acid. The acid value was 40 mg KOH / g, and Mn was 1.0 × 10⁻⁶. 5 .

[0096] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the stepwise water addition method, shear dispersion speed and time, reverse rotation sequence, number of high-pressure homogenization cycles, and post-cooling pH adjustment are all the same as in Step 2 of Example 1. PHBV resin and the copolyester B7 obtained in Step 1 are used in the same mass ratio as in Step 2 of Example 1, which is 70:30. The neutralizing agent is choline hydroxide with a neutralization degree of 80%. The melting temperature is adjusted to 190°C. The pre-dispersion is homogenized twice under high pressure at 100 MPa. After cooling, the pH of the system is finally adjusted to 8.8 to obtain a BioTen1031 aqueous emulsion with a target solid content of 40.2 wt%.

[0097] Example 12: Preparation of PLA aqueous emulsion (low acid value polyester).

[0098] Step 1. Preparation of self-emulsifying bio-based polyester B8: Following the process in Step 1 of Example 1, the dicarboxylic acid was 5 mol% FDCA, 45 mol% succinic acid, and 50 mol% adipic acid; the diols were 90 mol% 1,4-butanediol and 10 mol% 1,3-propanediol. Based on the total molar amount of all monomers participating in the polycondensation reaction, the total amount of functional monomers was 5 mol%, of which glycolic acid was 5 mol%, with an acid value of 20 mg KOH / g and Mn of 5.0 × 10⁻⁶. 4 .

[0099] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the mass ratio of polymer to polyester, the stepwise water addition method, the shear dispersion speed and time, the sequence of reverse rotation operations, the number of high-pressure homogenization cycles, and the pH adjustment operation after cooling are all the same as in Step 2 of Example 2. PLA resin and the copolyester B8 obtained in Step 1 are taken at a mass ratio of 80:20, the same as in Step 2 of Example 2. Potassium bicarbonate is used as the neutralizing agent, with a neutralization degree of 20%. The melting temperature is adjusted to 190°C. The pre-dispersion is homogenized twice under high pressure at 20 MPa. After cooling, the pH of the system is finally adjusted to 7.2 to obtain an aqueous PLA emulsion with a target solid content of 50.1 wt%.

[0100] Example 13: Preparation of BioTen 1031 aqueous emulsion (PHBV / high polymer ratio).

[0101] Step 1. Provide the copolyester B1 obtained in Step 1 of Example 1.

[0102] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the melting temperature, melting and mixing holding time, stepwise water addition method, shear dispersion speed and time, reverse rotation sequence, number of high-pressure homogenization cycles, and post-cooling pH adjustment are all the same as in Step 2 of Example 1. PHBV resin and copolyester B1 provided in Step 1 were used, with a mass ratio adjusted to 95:5. The neutralizing agent was choline hydroxide with a neutralization degree of 65%. The pre-dispersion was homogenized twice under high pressure at 120 MPa. After cooling, the final pH of the system was adjusted to 8.4 to obtain a BioTen1031 aqueous emulsion with a target solid content of 45.4 wt%.

[0103] Example 14: Preparation of PLA aqueous emulsion (low polymer ratio).

[0104] Step 1. Provide the copolyester B1 obtained in Step 1 of Example 1.

[0105] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the type and degree of neutralization of the neutralizing agent, the melting and mixing holding time, the stepwise water addition method, the shear dispersion speed and time, the reverse rotation sequence, the number of high-pressure homogenization cycles, and the post-cooling pH adjustment are all the same as in Step 2 of Example 2. PLA resin and copolyester B1 provided in Step 1 are taken, and the mass ratio is adjusted to 30:70. The melting temperature is the same as in Step 2 of Example 2, which is 190°C. The pre-dispersion is homogenized twice under high pressure at 20 MPa. After cooling, the final pH of the system is adjusted to 8.0 to obtain an aqueous PLA emulsion with a target solid content of 55.2 wt%.

[0106] Example 15: Preparation of BioTen 1031 aqueous emulsion (PHBV / high rosin content).

[0107] Step 1. Provide the copolyester B4 obtained in Step 1 of Example 8.

[0108] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the remaining melt mixing and holding time, stepwise water addition method, shear dispersion speed and time, reverse operation sequence, number of high-pressure homogenization cycles, and post-cooling pH adjustment are all the same as in Step 2 of Example 7. PHBV resin and copolyester B4 provided in Step 1 were used, and high-softening-point modified rosin ester C5 was added additionally during the melt mixing stage. The polymer:polyester:rosin mass ratio was 60:30:10. The neutralizing agent was choline hydroxide with a neutralization degree of 65%. The melting temperature was the same as in Step 2 of Example 7, at 180°C. The pre-dispersion was homogenized twice under high pressure at 60 MPa. After cooling, the final pH of the system was adjusted to 8.3, and the system was devastated at 40°C and -0.08 MPa for 30 min to remove trace organic volatiles, resulting in an aqueous emulsion of BioTen1031 with a target solid content of 45.1 wt%.

[0109] Example 16: Preparation of BioTen 1034 aqueous emulsion (PHBH).

[0110] Step 1. Provide the copolyester B3 obtained in Step 1 of Example 3.

[0111] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the stepwise water addition method, shear dispersion speed and time, reverse rotation sequence, number of high-pressure homogenization cycles, and post-cooling pH adjustment are all the same as in Step 2 of Example 1. The polymer is replaced with PHBH resin. The polymer to polyester mass ratio is 70:30. The melt temperature is adjusted to 150°C, and the neutralizing agent is L-arginine with a neutralization degree of 65%. The pre-dispersion is homogenized twice under high pressure at 40 MPa. After cooling, the final pH of the system is adjusted to 8.1 to obtain a BioTen1034 aqueous emulsion with a target solid content of 45.0 wt%.

[0112] Example 17: Preparation of PCL aqueous emulsion (PCL / low temperature preparation).

[0113] Step 1. Provide the copolyester B2 obtained in Step 1 of Example 2.

[0114] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the type and degree of neutralization of the neutralizing agent, the stepwise water addition method, the sequence of phase reversal operations, the number of high-pressure homogenization cycles, and the post-cooling pH adjustment are all the same as in Step 2 of Example 2. The polymer is replaced with PCL resin. The polymer to polyester mass ratio is 75:25. The melt mixing temperature is adjusted to 95°C, and the shear speed is adjusted to 4000 rpm. The pre-dispersion is homogenized twice under high pressure at 30 MPa. After cooling, the final pH of the system is adjusted to 8.2 to obtain a PCL aqueous emulsion with a target solid content of 50.0 wt%.

[0115] Example 18: Preparation of BioTen 1031 aqueous emulsion (PHBV / high shear preparation).

[0116] Step 1. Provide the copolyester B1 obtained in Step 1 of Example 1.

[0117] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the mass ratio of polymer to polyester, the type and degree of neutralization, the melt mixing and holding time, the stepwise water addition method, the sequence of phase inversion operations, the high-pressure homogenization pressure and number of times, and the post-cooling pH adjustment are all the same as in Step 2 of Example 1. PHBV resin and copolyester B1 provided in Step 1 are used in a mass ratio of 70:30. During the phase inversion emulsification stage, the shear speed is adjusted to 20,000 rpm. The pre-dispersion is homogenized twice under high pressure at 40 MPa. After cooling, the final pH of the system is adjusted to 8.2 to obtain a BioTen1031 aqueous emulsion with a target solid content of 45.1 wt%.

[0118] Example 19: Preparation of PHBV aqueous emulsion (lower limit of parameter window).

[0119] Step 1. Provide the copolyester B8 obtained in Step 1 of Example 12.

[0120] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the stepwise water addition method, the reverse operation sequence, and the cooling process are the same as in Step 2 of Example 1. PHBV resin and copolyester B8 provided in Step 1 are used in a mass ratio of 90:10. The neutralizing agent is potassium bicarbonate with a neutralization degree of 20%. The melting temperature is 180°C, and the shear speed is 4000 rpm. The pre-dispersion is homogenized once under high pressure at 20 MPa. After cooling, the pH is adjusted to 6.5, and the final solid content is 35.0 wt%. 50 It is 350nm.

[0121] Example 20: Preparation of PHBV aqueous emulsion (upper limit of parameter window).

[0122] Step 1. Provide the copolyester B7 obtained in Step 1 of Example 11.

[0123] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the stepwise water addition method, the reverse operation sequence, and the cooling process are the same as in Step 2 of Example 11. PHBV resin and copolyester B7 provided in Step 1 are used in a mass ratio of 30:70. The neutralizing agent is choline hydroxide with a neutralization degree of 80%. The melting temperature is 190°C, and the shear speed is 20,000 rpm. The pre-dispersion is homogenized three times under high pressure at 120 MPa. After cooling, the pH is adjusted to 9.0, and then concentrated under reduced pressure to achieve a final solid content of 60.0 wt%. 50 It is 80nm.

[0124] Example 21: Preparation of PHBV aqueous emulsion (low rosin end).

[0125] Step 1. Preparation of self-emulsifying bio-based copolyester B9: The diacid composition, diol composition, functional monomer composition, catalyst addition amount, esterification temperature and time, polycondensation temperature and time, and vacuum conditions of B9 are the same as those of copolyester B1 in Step 1 of Example 1. The amount of functional monomers used is based on the total molar amount of all monomers participating in the polycondensation reaction. The only difference is the addition of rosin acid as a chain end-capping unit in the later stage of polycondensation, with an addition amount of 1 wt%, based on the solids of the self-emulsifying bio-based polyester obtained from polycondensation. The acid value of the resulting copolyester B9 is 26 mg KOH / g, and Mn is 6.8 × 10⁻⁶. 4 .

[0126] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the remaining melt mixing and holding time, stepwise water addition method, shear dispersion speed and time, reverse rotation sequence, number of high-pressure homogenization cycles, and post-cooling pH adjustment are all the same as in Step 2 of Example 7. PHBV resin and the copolyester B9 obtained in Step 1 were used, and rosin ester C6 was added during the melt mixing stage. The polymer:polyester:rosin ratio was 69.5:30:0.5. The neutralizing agent was L-arginine, with a neutralization degree of 65%. The melt temperature was 180°C. The pre-dispersion was homogenized twice under high pressure at 40 MPa. After cooling, the final pH of the system was adjusted to 8.1, and the system was de-vaporized under reduced pressure at 40°C and -0.08 MPa for 30 min to remove trace amounts of volatile organic compounds, resulting in an aqueous emulsion with a solid content of 45.0 wt%.

[0127] Example 22: Preparation of PHBV aqueous emulsion (high rosin end).

[0128] Step 1. Preparation of self-emulsifying bio-based copolyester B10: The diacid composition, diol composition, functional monomer composition, catalyst addition amount, esterification temperature and time, polycondensation temperature and time, and vacuum conditions of B10 are the same as those of copolyester B1 in Step 1 of Example 1. The amount of functional monomers used is based on the total molar amount of all monomers participating in the polycondensation reaction. The only difference is the addition of rosin acid as a chain end-capping unit in the later stage of polycondensation, with an addition amount of 10 wt%, based on the solids of the self-emulsifying bio-based polyester obtained from polycondensation. The acid value of the resulting copolyester B10 is 27 mg KOH / g, and Mn is 6.0 × 10⁻⁶. 4 .

[0129] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the remaining melt mixing and holding time, stepwise water addition method, shear dispersion speed and time, reverse operation sequence, number of high-pressure homogenization cycles, and post-cooling pH adjustment are all the same as in Step 2 of Example 15. PHBV resin and the copolyester B10 obtained in Step 1 were taken, and rosin ester C5 was added during the melt mixing stage. The polymer:polyester:rosin ratio was 50:30:20. The neutralizing agent was choline hydroxide with a neutralization degree of 65%. The melting temperature was 190°C. The pre-dispersion was homogenized twice under high pressure at 60 MPa. After cooling, the final pH of the system was adjusted to 8.3, and the system was de-vaporized under reduced pressure at 40°C and -0.08 MPa for 30 min to remove trace amounts of volatile organic compounds, resulting in an aqueous emulsion with a solid content of 45.0 wt%.

[0130] Example 23: Preparation of PHBV aqueous emulsion (protective colloidal pathway).

[0131] Step 1. Provide the copolyester B1 obtained in Step 1 of Example 1.

[0132] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the remaining melt mixing and holding time, stepwise water addition method, shear dispersion speed and time, reverse rotation sequence, number of high-pressure homogenization cycles, and post-cooling pH adjustment are all the same as in Step 2 of Example 1. PHBV resin and copolyester B1 provided in Step 1 are used in a mass ratio of 70:30. The neutralizing agent is L-arginine with a neutralization degree of 70%. PVA aqueous solution is added during the water addition process, with a PVA dry basis percentage of 0.8 wt% based on the total solids of the emulsion. The pre-dispersion is homogenized twice under high pressure at 50 MPa. After cooling, the final pH of the system is adjusted to 8.0 to obtain a PHBV aqueous emulsion with a target solids content of 45.0 wt%.

[0133] Example 24: Preparation of PHBV aqueous emulsion (upper limit of trace process aids).

[0134] Step 1. Provide the copolyester B1 obtained in Step 1 of Example 1.

[0135] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the remaining melt mixing and holding time, stepwise water addition method, shear dispersion speed and time, reverse rotation operation sequence, high-pressure homogenization pressure and number of times, and post-cooling pH adjustment operation are all the same as in Step 2 of Example 1. PHBV resin and copolyester B1 provided in Step 1 are used in a mass ratio of 70:30. L-arginine is used as the neutralizing agent, with a neutralization degree of 70%. Based on the total solids of the emulsion, 0.05 wt% SDS and 0.05 wt% APG0810 are added, along with ethanol as a process aid. The amount of ethanol added is 0.50 wt% based on the theoretical finished product mass. The pre-dispersion is homogenized twice under high pressure at 40 MPa. After cooling, the final pH of the system is adjusted to 8.0, and the system is de-vaporized under reduced pressure at 40°C and -0.08 MPa for 30 min to remove ethanol. If necessary, deionized water is added to bring the solids content to 45.0 wt%, resulting in an emulsion with a solids content of 45.0 wt%.

[0136] Comparative example:

[0137] Comparative Example 1: Preparation of BioTen 1031 aqueous emulsion (polyester-free).

[0138] The preparation method of this comparative example is basically the same as that of Example 1, except that:

[0139] Step 1. No self-emulsifying bio-based copolyester B1 is provided, and no neutralizing agent is added;

[0140] Step 2. Take only PHBV resin, melt mix it at 180°C for 20 min, cool the system and keep it at 95°C, add deionized water in 10 equal portions according to the water addition method in Example 1, and shear dispersion at 8000 rpm; since the system lacks emulsifying stabilizing components, a stable phase-inversion pre-dispersion cannot be formed during the water addition process, so subsequent high-pressure homogenization treatment is not performed, and a homogeneous emulsion is not obtained in the end.

[0141] Comparative Example 2: Preparation of BioTen 1031 aqueous emulsion (with added SDS).

[0142] The preparation method of this comparative example is basically the same as that of Example 1, except that:

[0143] Step 1. Self-emulsifying bio-based copolyester B1 is not provided;

[0144] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the stepwise water addition method, shear dispersion speed and time, reverse rotation sequence, number of high-pressure homogenization cycles, and post-cooling pH adjustment are all the same as in Step 2 of Example 1. PHBV resin was melt-mixed at 180°C for 20 min, then the system was cooled and maintained at 95°C without adding copolyester B1. Sodium dodecyl sulfate (SDS) was pre-dissolved in deionized water and added along with the deionized water during the water addition stage. The total amount of SDS was 1.0 wt% based on the total solids of the emulsion. The pre-dispersion was homogenized twice under high pressure at 40 MPa. After cooling, the final pH of the system was adjusted to 7.5 to obtain the BioTen1031 aqueous emulsion (with added SDS).

[0145] Comparative Example 3: Preparation of BioTen 1031 aqueous emulsion (unneutralized).

[0146] The preparation method of this comparative example is basically the same as that of Example 1, except that:

[0147] Step 1. Provide PHBV resin and self-emulsifying bio-based copolyester B1 in a mass ratio of 70:30;

[0148] Step 2. After melting and mixing PHBV resin and copolyester B1 at 180°C for 20 min, the system was cooled and kept at 95°C without adding a neutralizing agent, and the degree of neutralization was 0%. Then, deionized water was added in 10 equal portions according to the water addition method in Example 1, and shear dispersion was performed at 8000 rpm. Since the hydrophilic carboxyl groups were not neutralized, the system could not undergo stable phase inversion, so subsequent high-pressure homogenization was not performed, and a homogeneous emulsion was not obtained in the end.

[0149] Comparative Example 4: Preparation of BioTen 1031 aqueous emulsion (low acid value polyester).

[0150] The preparation method of this comparative example is basically the same as that of Example 1, except that:

[0151] Step 1. Provide polyester B-Comp1 with a measured acid value of only 10 mg KOH / g;

[0152] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the stepwise water addition method, shear dispersion speed and time, reverse operation sequence, and post-cooling pH adjustment are all the same as in Step 2 of Example 1. PHBV resin and polyester B-Comp1 were added to a closed melt mixing container at a mass ratio of 70:30. After melt mixing at 180°C for 20 min, the system was cooled and maintained at 95°C. The neutralizing agent was still an L-arginine aqueous solution, and the degree of neutralization was calculated as 70% of the molar amount of the carboxyl hydrophilic groups in polyester B-Comp1. The pre-dispersion was homogenized twice under high pressure at 40 MPa. After cooling, the final pH of the system was adjusted to 7.6 to obtain the BioTen1031 aqueous emulsion (low acid value polyester).

[0153] Comparative Example 5: Preparation of PLA aqueous emulsion (low molecular weight polyester).

[0154] The preparation method of this comparative example is basically the same as that of Example 2, except that:

[0155] Step 1. Provide the measured Mn content as only 1.5 × 10⁻⁶. 4 Polyester B-Comp2 with an acid value of 150 mg KOH / g;

[0156] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the stepwise water addition method, shear dispersion speed and time, reverse operation sequence, number of high-pressure homogenization cycles, and post-cooling pH adjustment are all the same as in Step 2 of Example 2. PLA resin and polyester B-Comp2 are added to a closed melt mixing container at a mass ratio of 80:20 and melt-mixed at 190°C until homogeneous. Choline hydroxide is still used as the neutralizing agent, and the degree of neutralization is calculated as 65% of the molar amount of carboxyl hydrophilic groups in polyester B-Comp2. The pre-dispersion is homogenized twice under high pressure at 60 MPa. After cooling, the final pH of the system is adjusted to 7.8 to obtain the PLA aqueous emulsion (low molecular weight polyester).

[0157] Comparative Example 6: Preparation of BioTen 1031 aqueous emulsion (low pH).

[0158] The preparation method of this comparative example is basically the same as that of Example 1, except that:

[0159] Step 1. Prepare an aqueous emulsion of PHBV / copolyester B1 according to the method of Example 1;

[0160] Step 2. After the emulsion is cooled to 25°C, the pH of the system is adjusted dropwise to 5.0 using a 10wt% citric acid aqueous solution. Except for the pH adjustment conditions, the other raw material ratios, water addition methods, shear dispersion conditions, and high-pressure homogenization conditions are the same as in Example 1. After acid adjustment, the system exhibits significant flocculation, and the resulting sample no longer has any significance for final product testing.

[0161] Comparative Example 7: Preparation of BioTen 1031 aqueous emulsion (high acid value polyester).

[0162] The preparation method of this comparative example is basically the same as that of Example 1, except that:

[0163] Step 1. Provide polyester B-Comp3 with a measured acid value as high as 55 mg KOH / g;

[0164] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the stepwise water addition method, shear dispersion speed and time, reverse operation sequence, and post-cooling pH adjustment are all the same as in Step 2 of Example 1. PHBV resin and polyester B-Comp3 were added to a closed melt mixing container at a mass ratio of 70:30. After melt mixing at 180°C for 20 min, the system was cooled and maintained at 95°C. The neutralizing agent was still an L-arginine aqueous solution, and the degree of neutralization was calculated as 70% of the molar amount of the carboxyl hydrophilic groups in polyester B-Comp3. The pre-dispersion was homogenized twice under high pressure at 40 MPa. After cooling, the final pH of the system was adjusted to 7.8 to obtain the BioTen1031 aqueous emulsion (high acid value polyester).

[0165] Comparative Example 8: Preparation of BioTen 1031 aqueous emulsion (high molecular weight polyester).

[0166] The preparation method of this comparative example is basically the same as that of Example 1, except that:

[0167] Step 1. Provide the measured Mn value as 1.3 × 10⁻⁶. 5 Polyester B-Comp4;

[0168] Step 2. Preparation of the aqueous emulsion: Except for the specific adjustments described below, the stepwise water addition method, shear dispersion speed and time, reverse operation sequence, and post-cooling pH adjustment are all the same as in Step 2 of Example 1. PHBV resin and polyester B-Comp4 were added to a closed melt mixing container at a mass ratio of 70:30. After melt mixing at 180°C for 20 min, the system was cooled and maintained at 95°C. The neutralizing agent was still an L-arginine aqueous solution, and the degree of neutralization was calculated as 70% of the molar amount of the carboxyl hydrophilic groups in polyester B-Comp4. The pre-dispersion was homogenized twice under high pressure at 40 MPa. After cooling, the final pH of the system was adjusted to 8.0 to obtain the BioTen1031 aqueous emulsion (high molecular weight polyester).

[0169] Comparative Example 9: Preparation of PHBV aqueous emulsion (high pH).

[0170] The preparation method of this comparative example is basically the same as that of Example 1, except that:

[0171] Step 1. Prepare an aqueous emulsion of PHBV / copolyester B1 according to the method of Example 1;

[0172] Step 2. Preparation of aqueous emulsion: First, prepare an aqueous emulsion of PHBV / copolyester B1 according to Step 2 of Example 1. The raw material ratio, stepwise water addition method, shear dispersion speed and time, phase inversion operation sequence, and two high-pressure homogenization conditions at 40 MPa are all the same as in Step 2 of Example 1. Subsequently, after the emulsion is cooled to 25°C, the pH of the system is adjusted dropwise to 9.5 using a 10 wt% choline hydroxide aqueous solution to obtain a PHBV aqueous emulsion (high pH).

[0173] Comparative Example 10: Preparation of PHBV aqueous emulsion (high and medium neutrality).

[0174] The preparation method of this comparative example is basically the same as that of Example 1, except that:

[0175] Step 1. Take PHBV resin and copolyester B1 at a mass ratio of 70:30 and add them to a closed melt mixing container. After melting and mixing at 180°C for 20 minutes, cool the system and keep it at 95°C.

[0176] Step 2. Preparation of the aqueous emulsion: Except for adjusting the degree of neutralization to 90% of the molar amount of carboxyl hydrophilic groups in copolyester B1, the remaining steps of melt mixing and holding time, stepwise water addition, shear dispersion speed and time, phase inversion sequence, high-pressure homogenization conditions, and post-cooling pH adjustment are the same as in Step 2 of Example 1. The pre-dispersion was homogenized twice under high pressure at 40 MPa. After cooling, the pH of the system was finally adjusted to 8.6 to obtain the PHBV aqueous emulsion (high degree of neutralization).

[0177] Comparative Example 11: Preparation of PHBV aqueous emulsion (low softening point rosin ester).

[0178] The preparation method of this comparative example is basically the same as that of Example 7, except that:

[0179] Step 1. Still provide PHBV resin and copolyester B1;

[0180] Step 2. Preparation of the aqueous emulsion: Except for replacing the glycerol rosin ester C1 used in Step 2 of Example 7 with a low softening point rosin ester C7, the softening point of C7 is 75°C, the mass ratio of polymer:polyester:rosin, the melt mixing and holding time, the type and degree of neutralization of the neutralizing agent, the stepwise water addition method, the shear dispersion speed and time, the reverse rotation operation sequence, and the number of high-pressure homogenizations are all the same as in Step 2 of Example 7. The pre-dispersion is homogenized twice under high pressure at 40 MPa. After cooling, the pH of the system is finally adjusted to 8.1 to obtain the PHBV aqueous emulsion (low softening point rosin ester).

[0181] Comparative Example 12: Preparation of PHBV aqueous emulsion (high rosin content).

[0182] The preparation method of this comparative example is basically the same as that of Example 15, except that:

[0183] Step 1. Still provide PHBV resin, copolyester B4 and high softening point modified rosin ester C5;

[0184] Step 2. Preparation of the aqueous emulsion: Except for adjusting the mass ratio of polymer:polyester:rosin in Step 2 of Example 15 from 60:30:10 to 55:20:25, the other neutralizing agent type and degree of neutralization, melting temperature, melting mixing and holding time, stepwise water addition method, shear dispersion speed and time, reverse operation sequence, and number of high-pressure homogenizations are all the same as in Step 2 of Example 15. The pre-dispersion is homogenized twice under high pressure at 60 MPa. After cooling, the pH of the system is finally adjusted to 8.2 to obtain the PHBV aqueous emulsion (high rosin content).

[0185] Comparative Example 13: Preparation of PHBV aqueous emulsion (high rosin structural unit).

[0186] This comparative example is basically the same as the polyester preparation method in step 1 of Example 21, except that:

[0187] Step 1. Add rosin acid as a chain end capping unit in the later stage of polycondensation, with an addition amount of 12 wt%. Based on the solids of the self-emulsifying bio-based polyester obtained by polycondensation, copolyester B-Comp5 is obtained.

[0188] Step 2. Preparation of the aqueous emulsion: Except for replacing copolyester B1 in Step 2 of Example 1 with copolyester B-Comp5, the remaining steps of melt mixing and holding time, stepwise water addition, shear dispersion speed and time, reverse rotation sequence, number of high-pressure homogenization cycles, and pH adjustment after cooling are the same as in Step 2 of Example 1. PHBV resin and copolyester B-Comp5 are added to a closed melt mixing container at a mass ratio of 70:30. After melt mixing at 180°C for 20 min, the system is cooled and maintained at 95°C. The neutralizing agent is still an L-arginine aqueous solution, and the degree of neutralization is calculated as 70% of the molar amount of the carboxyl hydrophilic groups in copolyester B-Comp5. The pre-dispersion is homogenized twice under high pressure at 40 MPa. After cooling, the final pH of the system is adjusted to 8.2 to obtain the PHBV aqueous emulsion (high rosin structural unit).

[0189] Comparative Example 14: Preparation of PHBV aqueous emulsion (low molecular weight adjuvants exceeding the upper limit).

[0190] The preparation method of this comparative example is basically the same as that of Example 24, except that:

[0191] Step 1. Still provide PHBV resin and copolyester B1 in a mass ratio of 70:30;

[0192] Step 2. Preparation of the aqueous emulsion: Except that the amounts of SDS and APG0810 added in Step 2 of Example 24 were increased to 0.06 wt% of the total solids of the emulsion, and the total amount of both was increased to 0.12 wt%, and ethanol was used as a process aid, with its amount increased to 0.60 wt% of the theoretical finished product mass, and only pH was adjusted after cooling without vacuum devolatilization, the types and degrees of neutralization of the neutralizing agent, the melting and mixing holding time, the stepwise water addition method, the shear dispersion speed and time, the sequence of reverse operation, and the high-pressure homogenization pressure and number of times were all the same as in Step 2 of Example 24. The pre-dispersion was homogenized twice under high pressure at 40 MPa. After cooling, the pH of the system was finally adjusted to 8.0 to obtain the PHBV aqueous emulsion (low molecular weight aids exceeded the upper limit).

[0193] Comparative Example 15: Preparation of PHBV aqueous emulsion (high solids content).

[0194] The preparation method of this comparative example is basically the same as that of Example 1, except that:

[0195] Step 1. Take PHBV resin and copolyester B1 at a mass ratio of 70:30 and add them to a closed melt mixing container. After melting and mixing at 180°C for 20 minutes, cool the system and keep it at 95°C.

[0196] Step 2. Preparation of the aqueous emulsion: Except for increasing the target solid content to 65.0 wt% and determining the total water addition based on this target solid content, the remaining melt mixing and holding time, neutralizer type and degree of neutralization, stepwise water addition method, shear dispersion speed and time, reverse rotation sequence, high-pressure homogenization conditions, and post-cooling pH adjustment are all the same as in Step 2 of Example 1. The pre-dispersion was homogenized twice under high pressure at 40 MPa. After cooling, the final pH of the system was adjusted to 8.2 to obtain the PHBV aqueous emulsion (high solid content).

[0197] Application example:

[0198] Application Example 1: Testing of basic physical properties and physical stability of water-based emulsions.

[0199] This application example tests the basic physicochemical properties and long-term storage stability of the aqueous emulsions or dispersions prepared in Examples 1 to 24 and Comparative Examples 1 to 15. According to GB / T 1725-2007, 2.00 g of sample was weighed and placed in an aluminum foil tray, dried to constant weight in a 105°C forced-air drying oven, and the non-volatile content was calculated as the solid content; pH was measured at 25°C using a pH meter equipped with a standard electrode; D 50Particle size distribution was determined using a laser particle size analyzer. Samples were diluted with deionized water to 0.10 wt% with a light-blocking level of 15%. Zeta potential was measured using a nanoparticle size and zeta potential analyzer at 25°C with samples diluted to 0.05 wt%. Viscosity was measured using a rotational viscometer at 25°C with a No. 3 rotor and stable values ​​were read at 60 rpm. For storage stability testing, each sample was placed in a 50 mL stoppered glass bottle and left to stand for 3 months at 25±2°C. The percentage of the supernatant and sedimentation layer height relative to the total sample height was measured. The sample was then shaken 10 times by hand to restore homogeneity, and the D-value was measured again using the aforementioned method. 50 And calculate D after reconstitution 50 Rate of change.

[0200] Table 3. Results of basic physical properties and stability tests for the examples:

[0201]

[0202] Table 4. Comparative example basic physical properties and stability test results:

[0203]

[0204] Note: The symbol "-" in the table indicates that the sample is extremely unstable, resulting in complete stratification, precipitation, clumping, or flocculation and demulsification, making it impossible to form a homogeneous emulsion system. Therefore, it is impossible to determine the specific particle size, viscosity, or reconstitution data; or it indicates that the sample has expired and the test is meaningless.

[0205] Analysis: The test data from Example 1 objectively recorded the differences in basic physicochemical properties and long-term stability between Examples 1-24 and Comparative Examples 1-15. Experimental results show that all examples of the present invention can form stable emulsion systems, and their D... 50 Maintaining a particle size within the 80-350 nm range, with absolute Zeta potential values ​​≥30 mV, it exhibits excellent electrostatic stability and steric hindrance effect. Example 20 achieved an ultrafine particle size of 80 nm through high shear and process optimization. In contrast, the comparative examples showed that the lack of self-emulsifying polyester (Comparative Example 1, Comparative Example 3) or improper pH adjustment (Comparative Example 6) resulted in the inability to form a homogeneous and testable emulsion system; data from Comparative Examples 4, 5, and 8 demonstrate that deviations in polyester acid value or molecular weight from the specified range lead to D... 50 Significantly increased particle size and obvious sedimentation stratification were observed. Experimental results confirm the decisive role of molecular parameters of self-emulsifying bio-based polyesters in colloidal stability, demonstrating the technical advantages of this invention in controlling emulsion particle size and long-term stability.

[0206] Application Example 2: Testing of the barrier properties and application functions of paper coating.

[0207] This application example aims to verify the practical performance of the emulsion after forming a barrier coating on the paper surface, focusing on its water resistance, oil resistance, and gas barrier effects. Uncoated food-grade kraft paper with a basis weight of 70 g / m² was selected as the substrate. Coating was performed using a K Control Coater automatic coating machine at a coating speed of 10.0 m / min. An RK standard bar was used, and calibration was performed by weighing to ensure a dry coating basis weight of 10.0 g / m². After coating, the film was dried at 105°C for 2 min and then placed at 23°C and 50% RH for 24 h before testing. 60 The KIT oil repellency rating was determined according to GB / T 1540-2002, with three parallel tests and the average value taken. The KIT value was determined according to TAPPI T 559 cm⁻²2, with three parallel tests and the consistent result taken. Given that the sample in this application is a film-forming barrier coating, the KIT value is only used as an auxiliary indicator of surface oil repellency. The oil resistance of the sample is comprehensively evaluated in conjunction with the coating continuity and grease penetration observation results. The WVTR was determined according to GB / T 26253-2010, with a test temperature of 38.0℃, a relative humidity of 90%RH on the high-humidity side, and a dry carrier gas with ≤1%RH on the low-humidity side. The test area was 50 cm². The OTR was determined according to GB / T 19789-2021, with a test temperature of 23.0℃ and a test area of ​​50 cm². The WVTR decline rate and OTR decline rate are calculated as follows: decline rate (%) = [(X0-X1) / X0] × 100%, where X0 is the corresponding average value of the uncoated base paper and X1 is the corresponding average value of the coated paper sample.

[0208] The coating appearance and feel were evaluated under 500lx white light, a viewing distance of 30cm, and a viewing area of ​​100cm²: "Smooth and without defects" was defined as zero pinholes and the absence of orange peel, shrinkage craters, cracks, and runs; "Pinholes on the surface" was defined as visible holes with a diameter ≥0.2mm; and "Orange peel" was defined as continuous texture undulations affecting uniformity. The feel was evaluated by lightly touching the surface with a finger and rubbing it back and forth 10 times with a clean cotton cloth. "Smooth / non-sticky" was defined as a smooth surface without stickiness or fiber adhesion, while "sticky" was defined as a noticeable stickiness or dragging sensation. Flexibility was evaluated by observing whether cracks appeared at the creases after 10 180° folds. "Good flexibility / resistant to folding" was defined as no cracks, while "brittle / breakage at the crease" was defined as cracks or breakage.

[0209] Uncoating is defined as obvious demulsification and clumping under conditions of 10.0 m / min and a target dry coating amount of 10.0 g / m², resulting in the inability to coat continuously, or an exposed substrate area of ​​≥50% after coating; Moisture absorption and whitening is defined as obvious milky white atomization after being placed at 23℃ and 50%RH for 24 hours; Re-adhesion is defined as obvious adhesion or fiber adhesion after 10 back-and-forth rubbing of cotton cloth; Rough surface with a grainy feel is defined as at least 3 particles with a diameter ≥0.2 mm visible within a 100 cm² observation area under 500 lx white light and a 30 cm observation distance, or obvious grainy friction when touched with fingers.

[0210] Table 5. Test results of paper coating barrier performance in the examples:

[0211]

[0212] Table 6. Test results of barrier properties of paper coatings in comparative examples:

[0213]

[0214] Analysis: The barrier performance test in Example 2 objectively reflects the structure-property relationship between the coating structure and its properties. Examples 1-24 all exhibited good film-forming properties on the paper surface, and their Cobb... 60 Both water absorption and oil resistance are at ideal levels. In particular, Examples 15, 20, and 22 achieved extremely low moisture permeability and oxygen permeability reduction through the synergistic effect of self-emulsifying polyester and rosin components. Comparative data show that coatings prepared solely with traditional low-molecular-weight surfactants (Comparative Example 2) are prone to pinholes and have poor water resistance; while excessively high polyester acid values ​​(Comparative Example 7) cause the coating to absorb moisture and turn white, reducing barrier performance. Furthermore, inappropriate molecular weight or excessively high solid content (Comparative Examples 8 and 15) can lead to process defects such as orange peel or inability to coat. The test results objectively demonstrate that the dense composite coating constructed through a dual interface stabilization mechanism of this invention significantly improves the barrier performance of paper-based packaging while overcoming the technical bottleneck of poor film-forming properties in traditional bio-based coatings.

[0215] Application Example 3: Emulsion microstructure and stability under harsh conditions.

[0216] This application example utilizes transmission electron microscopy (TEM) and physical testing under harsh conditions to investigate the microstructure of latex particles and their stability in extreme environments. For TEM sample preparation, the emulsion to be tested was diluted to 0.05 wt% with deionized water, and a small amount was dropped onto a copper grid supported by a carbon film. After standing and drying, it was negatively stained with a 2 wt% phosphotungstic acid solution. The particle morphology, particle size, and interface structure were observed under a JEM-2100Plus transmission electron microscope at an accelerating voltage of 200 kV. The interface layer thickness was measured using ImageJ software on representative samples, with at least three representative images for each sample and at least 50 randomly selected particles. Table 7 records the results based on whether the particles formed a continuous or semi-continuous interface layer. In Example 1, the interface layer thickness was measured to be approximately 10–15 nm.

[0217] For centrifugal stability testing, place 10.0 mL of the emulsion in a centrifuge tube and centrifuge at 1500 × g for 30 min. Observe whether stratification or bottom sedimentation occurs. After centrifugation, if no visible stratification is observed, the supernatant layer height should be ≤2% of the total sample height, the sedimentation layer height should be ≤5% of the total sample height, and the sample should recover homogeneity after 10 hand shakes. 50 If the change rate is ≤10%, it is judged as "pass"; if visible stratification, the height of the settling layer is >5%, or if there is irresolvable flocculation / demulsification, it is judged as "fail".

[0218] For freeze-thaw stability testing, 10.0 mL of the emulsion sample was placed in a stoppered centrifuge tube and frozen at -20°C for 16 h. It was then removed and allowed to thaw at 25°C for 8 h until it returned to a fully fluid state. This process constituted one freeze-thaw cycle, and a total of three cycles were performed. After three cycles, if the sample showed no gelation, no visible flocculation, or oil separation, and could be restored to homogeneity after 10 hand shakes and met the D... 50 If the rate of change is ≤10%, it is judged as "pass"; if uniformity can be restored but D 50 If the rate of change is greater than 10% and less than or equal to 20%, it is judged as "barely passed"; otherwise, it is judged as "failed".

[0219] Table 7. Results of microstructure and stability tests under harsh conditions for the embodiments:

[0220]

[0221] Table 8. Comparative microstructure and stability test results under harsh conditions:

[0222]

[0223] Analysis: Application Example 3, through TEM characterization and stringent stability testing, provided an in-depth analysis of the emulsion's microstructure and resilience. TEM images confirmed that the particles in the examples exhibited a distinct core-shell structure, and this continuous interfacial layer effectively prevented the aggregation of hydrophobic cores. In the centrifugal stability test, Examples 1-24 all passed; in the freeze-thaw cycle test, all examples passed except for Examples 12 and 19, which barely passed. In particular, Examples 9 and 10, which introduced nano-reinforcing components, exhibited high kinetic stability under extreme physical shear and temperature fluctuations. In contrast, Comparative Example 2, lacking interfacial layer protection, rapidly demulsified after freeze-thaw cycles; Comparative Examples 7 and 10, due to excessive ionization and swelling of the interfacial layer, resulted in irresolvable gels after centrifugation. The experimental data objectively demonstrate that the interfacial film defined in this invention not only possesses good mechanical strength but also endows the system with extremely strong environmental adaptability, effectively coping with the extreme physical fields that may be encountered during industrial storage, transportation, and pumping.

[0224] Application Example 4: Emulsion safety compliance and solvent residue testing.

[0225] This application example aims to evaluate the basic formulation compliance indicators when using aqueous emulsions in the development of food contact paper-based materials, focusing on testing total residual organic solvents, anionic surfactant content, and total VOCs; compliance for end-use in food contact still needs to be evaluated separately in conjunction with total migration, specific migration, and sensory evaluation of the final coated product.

[0226] When testing the total amount of residual organic solvents, refer to the headspace-gas chromatography-mass spectrometry test conditions in GB 31604.60-2024, accurately weigh 1.0 g of emulsion sample into a headspace vial, equilibrate at 80℃ for 30 min and then inject the sample, and sum the amount of the target solvent detected to obtain the total amount of residual organic solvents, in mg / kg.

[0227] When testing the content of anionic surfactants, the content of free alkyl sulfates or alkylbenzene sulfonates in the emulsion shall be determined by direct two-phase titration, referring to GB / T 5173-2018.

[0228] For total VOC testing, the VOC content in the product was determined by gas chromatography, referring to GB / T 23986.2-2023.

[0229] The judgment criteria are as follows: when the total amount of residual organic solvents is ≤5000mg / kg, the content of anionic surfactants is ≤0.05wt%, and the VOC content is ≤10g / L, it is recorded as 'compliant'; when any of the above indicators exceeds the above limits, it is recorded as 'non-compliant'.

[0230] Table 9. Safety compliance test results of the example:

[0231]

[0232] Table 10 Comparative Security Compliance Test Results:

[0233]

[0234] Analysis: Application Example 4 addressed the basic formulation requirements for food contact packaging development, quantitatively detecting residues and VOCs. The analysis showed that, thanks to the application of a self-emulsification mechanism, the organic solvent residues and anionic surfactant content in Examples 1-24 were at low levels. For Examples 8, 15, 21, and 22, by adding a mild vacuum volatilization operation in the finished product stage, trace amounts of volatile organic compounds in the system could be reduced to undetectable levels. Although Example 24 introduced an ethanol additive into the process, after subsequent vacuum volatilization, the organic solvent residues in the finished product were also reduced to undetectable levels, and the VOC content remained low, generally exceeding industry-standard safety indicators. In contrast, Comparative Example 2, relying heavily on SDS emulsification, resulted in a significant exceedance of the anionic surfactant content; Comparative Example 14 was deemed non-compliant due to excessive addition of process additives. The test results objectively demonstrate that this invention reduces the risk of introduction and migration of harmful substances at the source by replacing most small molecule surfactants with self-emulsifying polyester and combining it with necessary post-treatment devolatilization operations. While maintaining high bio-based properties, it is beneficial for safety and regulatory compliance assessments in food packaging application development. For end-use applications in food contact, further evaluation is still required based on the total migration amount, specific migration amount, and sensory properties of the final product.

[0235] Application Example 5: Emulsion mechanical stability and machine adaptability test.

[0236] This application example aims to simulate a high-speed industrial coating and conveying process to test the mechanical stability and machine adaptability of the emulsion.

[0237] During the high-speed stirring stability test, 300g of emulsion was placed in a beaker and stirred continuously at 3000rpm for 30min using a disperser. Then, it was filtered through a 200-mesh filter and the residue was weighed. At the same time, it was observed whether there were gel particles formed by demulsification and obvious foam.

[0238] During the pumping shear stability test, the emulsion was circulated using a peristaltic pump at a flow rate of 2.0 L / min for 1 hour. Changes in emulsion flowability and whether emulsion breakage or pump blockage occurred were observed.

[0239] The evaluation criteria are as follows: "Excellent" is rated when there is no obvious foaming or overflow, no oil separation / layering, no pump blockage, and the 200-mesh filtration residue is 0.00g after high-speed stirring and pumping; "Good" is rated when there is no obvious foaming or overflow, no oil separation / layering, no pump blockage, and the 200-mesh filtration residue is <0.01g; "Good" is rated when there is no pump blockage and the filtration residue is ≥0.01g and ≤0.03g; "Pass" is rated when pumping can continue but the filtration residue is >0.03g and ≤0.05g, or there is a slight change in fluidity; "Poor" is rated when there is obvious foaming or overflow, pumping fluctuations, oil separation, or filtration residue >0.05g and <0.50g; "Poor" is rated when there is obvious layering / oil separation or filtration residue ≥0.50g and <2.00g; and "Fail" is rated when there is pump blockage, demulsification / caking, or filtration residue ≥2.00g.

[0240] Table 11 Mechanical stability test results of the examples:

[0241]

[0242] Table 12 Comparative mechanical stability test results:

[0243]

[0244] Analysis: Example 5 simulated the industrial high-speed coating and pumping process, objectively evaluating the mechanical stability of the emulsion. Test results showed that Examples 1-24 performed excellently under mechanical shear, with most samples exhibiting extremely low filtration residue and no pump blockage or gel formation. Example 18 further refined the particle size using an ultra-high shear process, achieving excellent processing adaptability. In contrast, Comparative Example 2 generated a large amount of persistent foam under stirring, interfering with pumping stability; Comparative Examples 5, 7, 8, and 12, due to improper molecular design or formulation, induced interfacial film rupture under high-speed shear, generating a large amount of gel agglomerates and leading to pump blockage. Data analysis indicates that this invention, by improving the cohesive strength and compatibility of the self-emulsifying interfacial film, endows the emulsion with excellent shear resistance, solving the common agglomeration and foaming problems of bio-based polymer emulsions during high-speed coating processing, demonstrating good potential for industrial application.

[0245] Application Example 6: Comprehensive test of interface wettability, anti-tack and foaming behavior.

[0246] This application example is used to evaluate the interfacial wettability, anti-tack, and foaming behavior of emulsion coatings. Coated paper prepared according to the method in Application Example 2 was selected as the test sample.

[0247] During the static water contact angle test, at 23℃ and 50%RH, 5μL of deionized water was dropped onto the coating surface using a contact angle measuring instrument, and the static contact angle was recorded at 5s. Five different locations were tested for each sample and the average value was taken.

[0248] During the hot-press blocking level test, two paper samples with their coated surfaces facing each other are stacked together and hot-pressed at 50℃ and 0.5MPa for 5 minutes. After cooling for 10 minutes, they are manually peeled off and the blocking level is evaluated: Level 0 is recorded when they can be easily separated without surface damage; Level 1 is recorded when there is slight adhesion but no coating transfer; Level 2 is recorded when there is obvious adhesion accompanied by local surface damage; and Level 3 is recorded when there is large-area peeling or coating transfer.

[0249] During the foaming test, 100g of emulsion was placed in a 250mL graduated cylinder, mechanically stirred at 2000rpm for 2min, and the foam height was recorded immediately. After standing for 5min, the foam retention height was recorded again.

[0250] When evaluating the adhesion, rub the coating surface back and forth 10 times with a clean cotton cloth. If there is no obvious adhesion, record it as "none". If there is a slight dragging feeling, record it as "slight". If there is obvious adhesion or fiber adhesion, record it as "obvious".

[0251] The comprehensive evaluation is judged in descending order as follows: "Excellent" is awarded when the static water contact angle is ≥99°, the thermo-pressing blockage level is 0, the initial foam height is ≤14mm, the 5-minute foam retention is ≤1mm, and there is no re-adhesion. If the "Excellent" condition is not met, the evaluation is "Good" if the static water contact angle is ≥86°, the thermo-pressing blockage level is ≤1, the initial foam height is ≤20mm, the 5-minute foam retention is ≤3mm, and there is no re-adhesion. If the above-mentioned higher-level conditions are not met, the evaluation is "Superior" if the static water contact angle is ≥87°, the thermo-pressing blockage level is ≤1, the initial foam height is ≤20mm, the 5-minute foam retention is ≤3mm, and there is no re-adhesion. When the foam height is ≤32mm, the foam retention after 5 minutes is ≤8mm, and the tackiness is not higher than 'slight', it is rated as 'good'; if the above-mentioned higher-level conditions are not met, and the static water contact angle is ≥84°, the hot-pressing blockage level is ≤1, the initial foam height is ≤26mm, the foam retention after 5 minutes is ≤5mm, and the tackiness is not higher than 'slight', it is rated as 'acceptable'; if the above conditions are not met and there is obvious tackiness, the blockage level is ≥2, or the foam retention after 5 minutes is >8mm, it is rated as 'poor' or 'bad'; if the sample cannot be tested normally or the overall performance is significantly failed, it is rated as 'fail'.

[0252] Table 13 Comprehensive test results of interface wettability, anti-tack and foaming behavior of the examples:

[0253]

[0254] Table 14. Comprehensive test results of interfacial wettability, anti-tack and foaming behavior of comparative examples:

[0255]

[0256] Analysis: Application Example 6 comprehensively evaluated the surface physical properties of the coating, including wettability, anti-re-adhesion, and foaming behavior. Examples 15, 20, and 22 exhibited static water contact angles exceeding 100° and a thermo-pressurization blocking rating of 0, indicating low surface energy and strong cohesion, demonstrating excellent moisture-proof and anti-adhesion capabilities. Example 23, by introducing a specific protective colloid, effectively suppressed the initial foam height and foam persistence of the system. In the comparative experiments, Comparative Examples 2 and 14 showed a significant decrease in contact angle and severe foaming due to additive residues; Comparative Examples 7 and 11 exhibited obvious thermo-pressurization blocking phenomena, even causing coating peeling. The experimental results objectively confirm that the present invention, through the precise formulation of self-emulsifying polyester and rosin-based components, significantly improves the natural defects of bio-based coatings, such as easy re-adhesion and easy foaming. While improving the hydrophobic properties of the interface, it ensures the quality stability of the coating during stacking and storage, thereby enhancing the practicality of the product.

[0257] Application Example 7: Determination of bio-based carbon content in emulsion solids and free-drying films.

[0258] This application example aims to verify the bio-based carbon content of the samples involved in Examples 1 to 24 and Comparative Examples 1 to 15 of the present invention in both the emulsion solids and film-forming states after dehydration. The bio-based carbon content was determined according to GB / T 39715.2-2021, and the result is expressed as the percentage of carbon derived from modern biomass in the total organic carbon of the sample. Considering that the uncoated base paper itself is a cellulose substrate with a high bio-based carbon content, which cannot accurately reflect the bio-based properties of the coating formulation itself, this application example uniformly uses emulsion solids and free-drying films as test objects.

[0259] For the preparation of emulsion solid samples, 20.0 g of each emulsion sample was placed in a polytetrafluoroethylene dish and pre-dried at 40℃ and -0.08 MPa for 12 h, followed by vacuum drying at 50℃ to constant weight, and then pulverized for later use. For the preparation of free-drying film samples, each emulsion was coated onto the surface of a release polyester film using the coating method described in Application Example 2, controlling the dry film basis weight to be 10.0 g / m², dried at 105℃ for 2 min, and then placed at 23℃ and 50% RH for 24 h before peeling, cutting, and use. Each sample was commissioned to a qualified third-party testing institution for parallel determination twice according to GB / T 39715.2-2021, and the average value was taken. The results were reported according to the sample organic carbon standard. Bio-based carbon content ≥80.0% was recorded as "high", and bio-based carbon content <80.0% was recorded as "lower". If a homogeneous emulsion solid or free-drying film sample that meets the test conditions of this application example cannot be obtained, the corresponding item is recorded as "-".

[0260] Table 15. Test results of bio-based carbon content in emulsion solids and free-drying films of representative examples:

[0261]

[0262] Table 16. Results of Bio-based Carbon Content Tests for Comparative Emulsion Solids and Free-Drying Films:

[0263]

[0264] Note: The symbol "-" in Table 16 indicates that the corresponding item is not applicable, not that the value is zero. Among them, Comparative Examples 1 and 3 did not obtain a homogeneous and stable emulsion during the preparation stage, and could not prepare emulsion solids and free-dry films that could represent the product composition; Comparative Example 6 showed obvious flocculation after adjusting the pH to 5.0, and the sample became invalid and had no testing significance; Although Comparative Example 15 could obtain a high solids content sample and the bio-based carbon content of the emulsion solids could be measured, it could not be continuously coated to form a film under the conditions of 10.0 m / min coating speed and target dry film quantitative amount of 10.0 g / m² specified in Application Example 2, so the bio-based carbon content of the free-dry film was not applicable.

[0265] Analysis: The test results of Application Example 7 show that Examples 1 to 24 of the present invention maintain a high bio-based carbon content in both the emulsion solids and free-drying film states after water removal. The bio-based carbon content of the emulsion solids in the examples is 80.9%–94.1%, and the bio-based carbon content of the free-drying film is 81.3%–94.5%. Among them, Examples 7, 8, 15, 21, and 22 have a further increased bio-based carbon content due to the introduction of rosin-based functional resin components or self-emulsifying bio-based polyesters containing rosin-based structural units in the formulation. Although Examples 5, 6, 12, 14, 19, and 20 are in the relatively low range within the implementation scope, they still maintain a high bio-based carbon content, indicating that the platform technology of the present invention has stable bio-based properties throughout the entire parameter window. Comparative Examples 1, 3, and 6 were not applicable because samples meeting the testing conditions of this application example could not be obtained. Comparative Example 15 was only measurable for emulsion solids and not for the free-drying film. Among the remaining measurable comparative examples, some samples, although having high bio-based carbon content, still struggled to balance emulsion stability, film-forming properties, and processing adaptability. For example, although Comparative Example 2 had relatively high bio-based carbon content in both emulsion solids and the free-drying film, its mechanical stability, foaming behavior, and coating barrier properties were significantly inferior to those of the embodiments of the present invention. Comparative Example 5, due to the use of an abnormally low molecular weight and high acid value polyester, had a bio-based carbon content that dropped below 80.0%, while emulsion stability and film-forming properties further deteriorated. These results corroborate the low residue and low VOC test results of Application Examples 1 to 6 and Application Example 4, demonstrating that the present invention can not only maintain a high bio-based carbon content but also balance emulsion stability, barrier properties, and industrial processing adaptability.

[0266] Experimental Results and Analysis:

[0267] Based on the data analysis of various embodiments and comparative examples, the technical platform described in this invention exhibits the following significant technical advantages and mechanistic features:

[0268] Structure-activity analysis of self-emulsifying bio-based polyester parameters:

[0269] This invention achieves efficient stabilization of various bio-based film-forming polymers by precisely controlling the molecular structure of self-emulsifying bio-based polyesters. Experiments show that an acid value in the range of 20-40 mg KOH / g is the key window for achieving ideal emulsification. Within this range, the neutralized carboxyl hydrophilic groups form a double layer with sufficient charge density at the particle interface of the dispersed phase, providing strong electrostatic repulsion and steric hindrance effects. If the acid value is below 20 mg KOH / g (as in Comparative Example 4), the hydrophilicity of the polyester itself is insufficient to support the interfacial energy conversion during the phase inversion process, resulting in coarse particle size and uneven distribution. If the acid value exceeds 40 mg KOH / g (as in Comparative Example 7), although the emulsion particle size is extremely fine, the coating will develop micropores due to excess hydrophilic groups during film formation, leading to Cobb... 60 The value increased significantly, compromising the overall barrier properties of the coating. Meanwhile, the number-average molecular weight Mn was 5.0 × 10⁻⁶. 4 -1.0×10 5 Within the specified range, the mechanical strength of the interfacial film is ensured. High molecular weight polyester can form good physical entanglement with the film-forming polymer during the melt compounding stage, effectively improving the emulsion's resistance to polymerization under high-speed shear conditions and overcoming the defects of traditional low molecular weight emulsifiers, such as easy migration and poor water resistance.

[0270] Synergistic stabilization mechanism of rosin-based components and nano-reinforcement:

[0271] This invention innovatively introduces rosin-based components as hydrophobic synergists and compatibility enhancers. The unique tricyclic diterpenoid structure of the rosin group exhibits excellent affinity for hydrophobic matrices such as PHA and PLA, and its distribution in the shell region of the dispersed phase particles significantly improves the static water contact angle and KIT oil repellency of the coating. Data from Examples 7 and 15 show that the introduction of the rosin component not only enhances hydrophobicity but also improves the hot-pressing anti-clogging performance of the coating due to its tackifying properties. Furthermore, a Pickering stabilizing system constructed by introducing CNC nanocellulose crystals or silica nanoparticles (Examples 9 and 10) forms a rigid physical barrier on the particle surface. This barrier effectively resists the mechanical stress caused by ice crystal growth during freeze-thaw cycles, preventing collisional aggregation of latex particles and giving the system excellent environmental adaptability.

[0272] Safety, process adaptability, bio-based carbon content and film formation control analysis:

[0273] This invention balances high bio-based carbon content, safety compliance, and film-forming control. Through a self-emulsification mechanism, the entire product line essentially eliminates reliance on externally added low-molecular-weight anionic surfactants (such as SDS), reducing the risks of bubbling, re-adhesion, and migration during paper coating. Application Example 4 shows that the organic solvent residue, anionic surfactant content, and VOC content of the emulsion of this invention are all at low levels. Application Example 7 further demonstrates that the emulsion solids and free-dry films of Examples 1 to 24 all have high bio-based carbon content, quantifying the bio-based properties of the system across the entire parameter window. Meanwhile, Comparative Examples 1, 3, and 6 are not applicable due to sample instability; Comparative Example 15 is only measurable for the emulsion solids and not for the free-dry film; among the remaining measurable comparative examples, although some samples also have high bio-based carbon content, it is still difficult to balance emulsion stability, film-forming properties, and processing adaptability. This indicates that this invention does not simply increase bio-based carbon content, but rather achieves a comprehensive performance balance while maintaining high bio-based properties. For end-use applications in food contact, further evaluation is still needed, considering factors such as total migration, specific migration, and sensory characteristics of the final product. On the process side, the combination of ultra-high shear (Example 18) and high-pressure homogenization will... 50 By controlling the particle size to below 200nm, this fine particle size distribution enables the coating to rapidly achieve capillary pressure-driven particle deformation and fusion during the drying process, forming a dense, flat, and pinhole-free continuous barrier layer, which significantly improves the barrier efficiency against oxygen and water vapor.

[0274] Correlation analysis of core process parameters:

[0275] The various performance indicators and process parameters of this invention exhibit significant nonlinear correlations and synergistic effects. During the phase inversion process, the emulsion D... 50 Driven by both the acid value and shear work of self-emulsifying polyesters: as the acid value increases within the range of 20-40 mg KOH / g, the interfacial energy of the system decreases, D 50 The particle size distribution shows a shrinkage trend from 340 nm to 80 nm, reflecting the enhanced inhibition of particle growth due to the increased density of hydrophilic groups. Simultaneously, Mn has a dual effect on both the system viscosity and the interfacial film continuity; when Mn is at 1.0 × 10⁻⁶... 5Near the target concentration, the cohesive strength of the interfacial film reaches its peak, effectively preventing Oswald curing during storage. However, further increasing the molecular weight leads to excessively high melt viscosity, causing microphase separation. The amount of rosin added is positively correlated with anti-tack performance, but there is a critical concentration point of 20 wt%. Exceeding this limit will cause macroscopic phase separation within the particles due to differences in solubility parameters, resulting in a decrease in the KIT grade. Regarding solid content, a wide window of 35.0-60.0 wt% ensures the controllability of coating quantity. Under high solid content, the film formation rate is faster and the density is better. However, once it rises above 65.0 wt%, the rheological behavior of the system changes abruptly, and the viscosity increases dramatically, making continuous coating operations impossible. In summary, the precise matching of various parameter windows in this invention jointly constructs a highly efficient waterborne platform that achieves a dynamic balance between stability, barrier properties, and processability.

[0276] In summary, this invention, through molecular design and multi-component synergy, successfully addresses the technical challenge of balancing stability and high performance in the water-based transformation process of bio-based polymers, providing a promising industrial solution for the green packaging industry.

[0277] Those skilled in the art should understand that the above embodiments are merely exemplary and not intended to limit the scope of the invention. The scope of protection of the present invention is defined by the appended claims. Any modifications, equivalent substitutions, improvements, etc., made to the technical solutions of the present invention within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A self-emulsifying, bio-based polyester-stabilized aqueous emulsion of various bio-based polymers, characterized in that, The aqueous emulsion has water as the continuous phase and contains dispersed phase particles; the dispersed phase particles contain a hydrophobic bio-based film-forming polymer and a self-emulsifying bio-based polyester, and the hydrophobic bio-based film-forming polymer and the self-emulsifying bio-based polyester are different polymer components. The self-emulsifying bio-based polyester is a copolyester containing carboxyl hydrophilic groups or their salts, obtained by polycondensation of furan dicarboxylic acid, aliphatic dicarboxylic acid, diol and carboxyl-containing functional monomers. After neutralization, the hydrophilic groups exist at least partially in the form of salts and form a continuous or semi-continuous stable layer at the interface of the dispersed phase particles, so as to achieve interface stabilization and compatibility of the hydrophobic bio-based film-forming polymer. The self-emulsifying bio-based polyester has an acid value of 20–40 mg KOH / g and a number-average molecular weight of 5 × 10⁻⁶. 4 ~1×10 5 ; The aqueous emulsion has a solid content of 35–60 wt%, D 50 The wavelength range is 80–350 nm, and the pH range is 6.5–9.

0. The aqueous emulsion contains a rosin-based functional resin component; The rosin-based functional resin component is selected from rosin, rosin acid, rosin salt, rosin ester, hydrogenated rosin, disproportionated rosin, polymerized rosin, maleated rosin, fumarate rosin, dimerized rosin acid, and combinations thereof; When the rosin-based functional resin component is rosin ester, the softening point of the rosin ester is 80–130°C; and the content of the rosin-based functional resin component, based on the total emulsion solids, is 0.5–20 wt%. The self-emulsifying bio-based polyester further comprises a rosin-based structural unit derived from rosin acid; Rosin acid is used as a chain end capping unit or a hydrophobic compatibility unit, and the amount of rosin-based structural unit introduced is 1 to 10 wt%, based on self-emulsifying bio-based polyester solids. The total amount of added low-molecular-weight surfactants, based on the total solids of the emulsion, is ≤0.1wt%, including alkyl sulfate anionic surfactants, alkylbenzene sulfonate anionic surfactants, and optional nonionic low-molecular-weight surfactants; wherein the total amount of alkyl sulfate anionic surfactants and alkylbenzene sulfonate anionic surfactants is 0-0.05wt%; and based on the finished product weight, the organic solvent content of the aqueous emulsion is ≤0.5wt%; the bio-based carbon content of the emulsion solids after drying to constant weight and the free dry film formed therefrom, as determined according to GB / T39715.2-2021, is 80.0%-95.0%. The hydrophobic bio-based film-forming polymer is selected from one or more of the following: polyhydroxy fatty acid esters and their copolymers or blends; polyesters obtained by polymerization of lactic acid or lactide monomers and their copolymers or blends; aliphatic polyesters obtained by polycondensation of diacids and diols and their copolymers or blends; or furanyl dicarboxylic acid-based polyesters and their copolyesters or blends obtained by polycondensation of furanyl dicarboxylic acid or its esters and diols.

2. The self-emulsifying bio-based polyester-stabilized multi-type bio-based polymer aqueous emulsion according to claim 1, characterized in that, The polyhydroxy fatty acid esters include poly(3-hydroxybutyrate), poly(3-hydroxybutyrate-3-hydroxyhexanoate), poly(3-hydroxybutyrate-4-hydroxybutyrate), poly(3-hydroxybutyrate-3-hydroxyvalerate), and medium- and long-chain polyhydroxy fatty acid esters, wherein the medium- and long-chain polyhydroxy fatty acid esters include poly(3-hydroxyhexanoate), poly(3-hydroxyheptanoate), poly(3-hydroxyoctanoate), poly(3-hydroxynonanoate), poly(3-hydroxydecanoate), poly(3-hydroxyundecanoate), poly(3-hydroxydodecanoate), poly(3-hydroxytetrate), and poly(3-hydroxytetradecanoate). Polyesters and their copolymers or blends obtained by polymerization of lactic acid or lactide monomers, wherein the comonomers of the copolymers include glycolic acid or glycolide, ε-caprolactone, δ-valerolactone, p-dioxanone, trimethylene carbonate or combinations thereof. Aliphatic polyesters and their copolymers or blends obtained by polycondensation of a diacid and a diol, wherein the diacid is selected from succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, itaconic acid, fumaric acid, maleic acid or combinations thereof, and the diol is selected from ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, neopentanediol, isosorbide or combinations thereof; Furan dicarboxylic acid-based polyesters and their copolyesters or blends obtained by polycondensation of furan dicarboxylic acid or its esters with a diol, wherein the diol is selected from ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, isosorbide, or combinations thereof.

3. The self-emulsifying bio-based polyester-stabilized multi-type bio-based polymer aqueous emulsion according to claim 1, characterized in that, The self-emulsifying bio-based polyester is a copolyester obtained by polycondensation of a dicarboxylic acid, a diol, and a functional monomer containing a carboxyl group. The dicarboxylic acid includes furanyl dicarboxylic acid and aliphatic dicarboxylic acid, wherein the aliphatic dicarboxylic acid is selected from one or more of succinic acid, glutaric acid, adipic acid, pimelic acid, octanoic acid, azelaic acid, sebacic acid, undecanoic acid, dodecanoic acid, itaconic acid, fumaric acid, and maleic acid; The diol is selected from one or more of ethylene glycol, 1,4-butanediol, 1,3-propanediol, 1,5-pentanediol, 1,6-hexanediol and isosorbide; The functional monomer is selected from one or more of citric acid, malic acid, glycolic acid, and lactic acid; The content of furanyl dicarboxylic acid is 5–40 mol based on the molar amount of dicarboxylic acid; the total content of the functional monomer is 5–15 mol based on the total molar amount of all monomers participating in the polycondensation reaction.

4. The self-emulsifying bio-based polyester-stabilized multi-type bio-based polymer aqueous emulsion according to claim 1, characterized in that, The mass ratio of the hydrophobic bio-based film-forming polymer to the self-emulsifying bio-based polyester is 95:5 to 30:70, based on the total solid content of the two polymers. The degree of neutralization of the carboxyl hydrophilic groups is based on the molar amount of carboxyl hydrophilic groups in the self-emulsifying bio-based polyester, and is 20% to 80%. The neutralizing agent used for neutralization is selected from one or more of L-arginine, choline hydroxide, sodium bicarbonate, and potassium bicarbonate.

5. The self-emulsifying bio-based polyester-stabilized multi-type bio-based polymer aqueous emulsion according to claim 1, characterized in that, The aqueous emulsion contains a protective colloid, a rheology modifier, or a Pickering particle stabilizer. The protective colloid or rheology modifier is selected from one or more of cellulose and its derivatives, starch and its derivatives, xanthan gum, pectin, gum arabic, alginate, lignin and its derivatives, and polyvinyl alcohol. The Pickering particle stabilizer is selected from one or more of the following: nanocellulose crystals, nanocellulose fibers, lignin nanoparticles, starch nanoparticles, chitosan nanoparticles, silica nanoparticles, montmorillonite, and kaolin.

6. The self-emulsifying bio-based polyester-stabilized aqueous emulsion of various bio-based polymers according to claim 1, characterized in that, The aqueous emulsion has an absolute Zeta potential value ≥30mV and exhibits the following storage stability: after standing in a sealed container at 25±2℃ for 3 months, the height of the supernatant layer accounts for ≤2% of the total sample height, and the height of the sediment layer accounts for ≤5% of the total sample height; it can be restored to homogeneity after being shaken 10 times by hand, and D 50 The rate of change is ≤10%.

7. A method for preparing a self-emulsifying bio-based polyester-stabilized aqueous emulsion of multiple bio-based polymers according to claim 1, characterized in that, The preparation method includes the following steps: Step 1. Provide hydrophobic bio-based film-forming polymer, self-emulsifying bio-based polyester, neutralizer, and rosin-based functional resin components and additives as needed; Step 2. Heat the hydrophobic bio-based film-forming polymer and the self-emulsifying bio-based polyester until softened or melted and mix them; when the rosin-based functional resin component is provided in Step 1, add the rosin-based functional resin component and mix it with the molten system to obtain a molten composite phase; Step 3. Add a neutralizing agent to the molten composite phase obtained in Step 2 to make the degree of neutralization of the carboxyl hydrophilic groups of the self-emulsifying bio-based polyester 20-80%, thereby obtaining a neutralized molten composite phase; Step 4. Under shear dispersion conditions, water is gradually added to the neutralized melt composite phase obtained in step 3 to cause the system to undergo phase inversion and form an oil / water type aqueous dispersion with water as the continuous phase, thus obtaining a pre-dispersion. Step 5. The pre-dispersion obtained in Step 4 is subjected to high-pressure homogenization to refine the particle size, thereby obtaining the median particle size D. 50 It is an aqueous emulsion or aqueous dispersion with a wavelength of 80–350 nm; Step 6. Cool and adjust the pH to 6.5–9.0 to obtain the finished product; The melting and bonding temperature is 95–220℃; the shearing speed is 4000–20000 rpm; and the homogenization pressure is 20–120 MPa.

8. The application of the self-emulsifying bio-based polyester-stabilized multi-type bio-based polymer aqueous emulsion as described in claim 1, characterized in that, Used for paper barrier coatings and paper-based packaging coatings, the barrier coating is used to reduce the penetration of water, grease and oxygen into the paper.

9. The application of the self-emulsifying bio-based polyester-stabilized multi-type bio-based polymer aqueous emulsion according to claim 1, characterized in that, Used for paper barrier coatings and paper-based packaging coatings, the barrier coating is used to reduce the penetration of water vapor into the paper.

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