Monomolecular difunctional modifier, preparation method thereof, modified inorganic layered material, high-barrier coating composition, water-based coating liquid and high-barrier film

Abstract

The invention provides a monomolecular difunctional modifier and a preparation method thereof, and a modified inorganic layered material, a high-barrier water-based coating composition and a high-barrier film applying the same. The modified inorganic layered material has the length-diameter ratio of more than or equal to 200, the turbidity of 1wt% water dispersion liquid of less than or equal to 150NTU and no sedimentation after standing for more than or equal to 120 days, and the comprehensive performance of the modified inorganic layered material is obviously superior to that of a traditional step-by-step modified product; the modified inorganic layered material can construct an efficient and compact'maze 'barrier structure in a coating under the low addition amount of 1-5wt%, so that the high-barrier film simultaneously has excellent gas barrier property, high light transmittance and low haze, the water vapor transmission rate (WVTR) of the high-barrier film is less than or equal to 0.66 g / (m.day), the oxygen transmission rate (OTR) of the high-barrier film is less than or equal to 0.51 cc / (m.day), the light transmittance of the high-barrier film is greater than or equal to 90.1%, and the haze of the high-barrier film is less than or equal to 3.4%.

Description

Technical Field

[0001] This invention relates to the field of polymer composite materials technology, and particularly to single-molecule bifunctional modifiers and their preparation methods, as well as modified inorganic layered materials, high-barrier coating compositions, aqueous coating solutions, and high-barrier films. Background Technology

[0002] Inorganic oxide coatings (such as AlOx and SiOx) are widely used in high-end packaging and flexible electronic packaging due to their excellent gas barrier properties and high transparency. However, the inherent brittleness and microscopic defects of these coatings make them prone to cracking under mechanical stresses such as bending and friction, leading to a significant decrease in barrier performance. To avoid the degradation of barrier performance due to bending, a water-based barrier coating is usually applied to their surface to provide mechanical protection and synergistically improve barrier performance.

[0003] Introducing inorganic layered materials (such as montmorillonite) into water-based coatings can create a "maze effect," such as... Figure 2 As shown, when the aspect ratio (L / W) of the modified inorganic layered material in the coating is larger, under the same addition amount of the modified inorganic layered material, the gas transport path in the coating is extended to a greater extent, and correspondingly, the gas barrier performance of the coating is better. Extending the gas diffusion path is an effective strategy to improve barrier performance. However, commercially available inorganic layered materials often suffer from insufficient aspect ratio (the ratio of particle size to thickness of the inorganic layered material) and poor dispersibility in aqueous systems, making it easy to agglomerate and settle. This makes it difficult to fully realize their theoretical performance, and agglomeration introduces defects, deteriorating the optical and mechanical properties of the coating.

[0004] Existing modification methods mostly employ single-function or stepwise modification. For example, CN109650400A uses an organic solvent intercalation method to prepare ultrathin montmorillonite nanosheets, improving the aspect ratio, but it does not solve the problem of dispersion stability in aqueous systems, and the process has poor environmental friendliness. CN1796465A uses a "two-step method," first using quaternary ammonium salt intercalation to expand the interlayer spacing, and then using a silane coupling agent to improve dispersibility. However, this method suffers from the problem in aqueous systems that both the intercalating agent and the dispersant rely on the limited ion exchange sites on the surface of the inorganic layered material. The intercalating agent usually has a higher binding energy and will replace or repel the already adsorbed dispersant in subsequent steps; while if the dispersant is added later, it is difficult to obtain effective binding sites and form a stable adsorption layer. Therefore, regardless of the process sequence, the competition for functional sites between the two will lead to a trade-off between exfoliation efficiency and dispersion stability. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a single-molecule bifunctional modifier and its preparation method, as well as modified inorganic layered materials, high-barrier coating compositions, aqueous coating solutions, and high-barrier films. This molecular structure integrates intercalation and dispersion functions: its intercalation functional end is a residue derived from a specific amino acid and capable of protonation into a protonated amino group (-NH3⁺), which can be strongly anchored to the negatively charged surface of layered silicate sheets through ion exchange; its dispersion functional end is a hydrophilic polymer chain with a number-average molecular weight of 300-5000, providing sterically stable modified inorganic layered material sheets after exfoliation; the intercalation and dispersion functional ends are covalently connected via amide or ester bonds, ensuring they act synergistically as a single entity during the modification process, effectively avoiding site competition and fundamentally solving the problems of low efficiency and performance limitations caused by site competition in traditional processes. Furthermore, amino acid residues, acting as rigid spacer arms, not only effectively reduce the steric hindrance of high-molecular-weight hydrophilic segments in solution and improve the diffusion and anchoring efficiency of active end groups between narrow inorganic layered material layers, but also form auxiliary hydrogen bonds with the surface of inorganic layered material sheets through amide bonds. Together with ionic bonds, this constitutes a "dual anchoring" mode, significantly enhancing the binding strength of the modifier on the surface of the inorganic layered material and achieving effective synergy between intercalation and dispersion functions. This modifier can simultaneously achieve efficient intercalation and exfoliation and stable dispersion of inorganic layered materials, thereby improving the aspect ratio and dispersion stability of the modified inorganic layered materials. This results in high-barrier films exhibiting excellent gas barrier properties, high light transmittance, and low haze when applied in high-barrier coatings.

[0006] The object of this invention is achieved by providing a single-molecule bifunctional modifier, the molecular structure of which comprises: The intercalation functional end is derived from a protonable amino acid residue, wherein the amino acid is at least one of glycine, lysine, serine, aspartic acid, and glutamic acid. It can carry a positive charge under acidic conditions, i.e., it has protonated amino groups, and can exchange ions with the negative charge of layered silicate sheets; The dispersing functional end is a hydrophilic polymer chain segment, wherein the hydrophilic polymer chain segment is at least one of polyethylene glycol chain, polyacrylic acid chain, polystyrene sulfonate chain or polyphosphate chain, and the number average molecular weight is 300~5000. The intercalation functional end and the dispersion functional end are covalently connected by amide bonds or ester bonds.

[0007] A method for preparing a single-molecule bifunctional modifier includes the following steps: (1) Activate the carboxyl group of amino acids to obtain an amino acid active ester intermediate; the amino acid is at least one of glycine, lysine, serine, aspartic acid, and glutamic acid; (2) The amino acid active ester intermediate is condensed with terminal amino polyethylene glycol or terminal amino polyacrylic acid to form amide bonds or ester bonds.

[0008] A modified inorganic layered material, comprising the following steps: (1) Disperse the inorganic layered material in deionized water and then subject it to ultrasonic treatment; (2) Add the monomolecular bifunctional modifier and adjust the pH to 4-5, then react at 60-90℃ for 4-8 hours to obtain the modified inorganic layered material.

[0009] A high-barrier coating composition, characterized in that it comprises the following components by weight percentage: (1) Waterborne film-forming resin: 90-97%; (2) Crosslinking agent: 2-5%; (3) The modified inorganic layered material according to claim 3: 1-5%.

[0010] The aqueous film-forming resin is at least one of aqueous polyurethane, aqueous acrylic resin, or polyvinyl alcohol.

[0011] The crosslinking agent is a silane coupling agent.

[0012] An aqueous coating liquid is prepared by the aforementioned high-barrier coating composition and a solvent; wherein, by weight percentage, the high-barrier coating composition is 3-8% and the solvent is 92-97%.

[0013] By weight percentage, the solvent contains the following components: (1) Deionized water: 90-100%; (2) The alcohol solvent is 5-10%, and the alcohol solvent is at least one of ethanol and isopropanol.

[0014] A high-barrier membrane comprising: Polymer substrate; inorganic oxide coating located on the surface of the polymer substrate; A high-barrier coating is formed on the surface of the inorganic oxide plating layer. The high-barrier coating is formed by coating and curing the high-barrier water-based coating liquid.

[0015] The polymer substrate is polyethylene terephthalate (PET), polypropylene (PP), or polyamide (PA); preferably biaxially oriented polyester (BOPET) or biaxially oriented polypropylene (BOPP), with a thickness of 6-50 μm. The inorganic oxide coating is at least one of aluminum oxide and silicon oxide, and has a thickness of 5-50 nm.

[0016] Compared with existing technologies, this invention provides a single-molecule bifunctional modifier, its preparation method, and modified inorganic layered materials, high-barrier waterborne coating compositions, and high-barrier membranes using the same modifier. The modified inorganic layered material has an aspect ratio ≥200, a turbidity of 1wt% aqueous dispersion ≤150 NTU, and shows no sedimentation after standing for ≥120 days. Its comprehensive performance is significantly better than traditional stepwise modified products. The modified inorganic layered material can construct a highly efficient and dense "labyrinth" barrier structure in the coating at a low addition amount of 1–5 wt%, enabling the high-barrier membrane to simultaneously possess excellent gas barrier properties, high light transmittance, and low haze. The high-barrier membrane has a water vapor transmission rate (WVTR) ≤0.66 g / (m²·day), an oxygen transmission rate (OTR) ≤0.51 cc / (m²·day), a light transmittance ≥90.1%, and a haze ≤3.4%. Attached Figure Description

[0017] Figure 1 Schematic diagram of the three-layer structure of the high-barrier membrane; Figure 2 : Schematic diagram of the "maze effect" constructed by modified inorganic layered materials in a coating; the gray area in the figure corresponds to the coating containing modified inorganic layered materials, which are dispersed in layers within the polymer coating; where: L represents the particle size of the modified inorganic layered materials, and W represents the thickness of the modified inorganic layered materials; the black dashed line with arrows on the right corresponds to the gas transport path in the pure polymer coating; the gray dashed line with arrows in the middle corresponds to the extended transport path formed by the gas detour in the polymer coating containing the modified inorganic layered materials.

[0018] Figure 3 Comparison of ¹H NMR spectra of PEG-NH2 and PEG-Gly: I, II, and III correspond to the characteristic peaks of methyl groups, the characteristic peak of methylene groups in polyethylene glycol, and the characteristic peak of methylene groups in glycine, respectively.

[0019] Figure 4 SEM image of PEG-Gly-MMT.

[0020] Figure 5 AFM morphology of PEG-Gly-MMT is shown in Figure A. Figures 1, 2, and 3 correspond to different linear scanning regions on the surface of the modified inorganic layered material. In Figure B, the curves of corresponding colors correspond to the height distribution curves of the corresponding linear scanning regions in Figure A, which are used to characterize the local height of the corresponding region (i.e., the local thickness of the modified inorganic layered material). For clarity, the curves corresponding to 2 and 3 are vertically offset by 4.5 nm and 9 nm, respectively. The characteristic heights of the linear scanning regions 1, 2, and 3 are approximately 3.7 nm, 4.3 nm, and 3.9 nm, respectively, which is the maximum height difference of each curve. Detailed Implementation

[0021] A single-molecule bifunctional modifier, the molecular structure comprising: The intercalation functional end is derived from a protonable amino acid residue, wherein the amino acid is at least one of glycine, lysine, serine, aspartic acid, and glutamic acid. It can carry a positive charge under acidic conditions, that is, it has a protonated amino group (-NH3). + ), and undergo ion exchange with the negative charge of the layered silicate sheets; The dispersing functional end is a hydrophilic polymer chain segment, wherein the hydrophilic polymer chain segment is at least one of polyethylene glycol chain, polyacrylic acid chain, polystyrene sulfonate chain or polyphosphate chain, and the number average molecular weight is 300~5000. The intercalation functional end and the dispersion functional end are covalently connected by amide bonds or ester bonds.

[0022] A method for preparing a single-molecule bifunctional modifier includes the following steps: (1) Activate the carboxyl group of amino acids to obtain an amino acid active ester intermediate; the amino acid is at least one of glycine, lysine, serine, aspartic acid, and glutamic acid; (2) The amino acid active ester intermediate is condensed with terminal amino polyethylene glycol or terminal amino polyacrylic acid to form amide bonds or ester bonds.

[0023] (3) The product obtained in step (2) can be purified to obtain the single-molecule bifunctional modifier.

[0024] A modified inorganic layered material, comprising the following steps: (1) Disperse the inorganic layered material in deionized water and then subject it to ultrasonic treatment; (2) Add the monomolecular bifunctional modifier and adjust the pH to 4-5, then react at 60-90℃ for 4-8 hours to obtain the modified inorganic layered material.

[0025] The modifier provided by this invention has a wide range of raw material applicability. The inorganic layered material can be montmorillonite (including sodium-based, lithium-based, etc.) or mica, etc. After modification with the modifier of this invention, its aspect ratio and dispersion stability can be significantly improved.

[0026] A high-barrier coating composition, characterized in that it comprises the following components by weight percentage: (1) Waterborne film-forming resin: 90-97%; (2) Crosslinking agent: 2-5%; (3) The modified inorganic layered material according to claim 3: 1-5%.

[0027] The high-barrier waterborne coating composition is suitable for a variety of waterborne film-forming resin systems, including but not limited to waterborne polyurethane, waterborne acrylic resin, and polyvinyl alcohol (preferably polyvinyl alcohol with a degree of alcoholysis > 98% and a degree of polymerization > 1000). These resins can be used alone or in combination to comprehensively adjust the barrier, flexibility, and adhesion properties of the coating.

[0028] Waterborne polyurethanes are preferably carboxyl-containing waterborne polyurethane dispersions, such as HP-1208 produced by Runchang Chemical or WPB-341 produced by Mitsui Chemicals of Japan.

[0029] Polyvinyl alcohol with a degree of hydrolysis greater than 98% and a degree of polymerization greater than 1000, such as PVA-117 or PVA-110 produced by Kuraray Corporation.

[0030] The appropriate crosslinking agents can be silane coupling agents (such as γ-aminopropyltriethoxysilane), aziridine, or carbodiimide, etc.

[0031] The crosslinking agent is a silane coupling agent.

[0032] An aqueous coating liquid is prepared by the aforementioned high-barrier coating composition and a solvent; wherein, by weight percentage, the high-barrier coating composition is 3-8% and the solvent is 92-97%.

[0033] By weight percentage, the solvent contains the following components: (1) Deionized water: 90-100%; (2) The alcohol solvent is 5-10%, and the alcohol solvent is at least one of ethanol and isopropanol.

[0034] like Figure 1 As shown, a high-barrier membrane comprises: Polymer substrate 1; inorganic oxide coating 2, located on the surface of the polymer substrate; A high-barrier coating 3 is formed on the surface of the inorganic oxide plating layer. The high-barrier coating is formed by coating and curing the high-barrier water-based coating liquid.

[0035] The polymer substrate is polyethylene terephthalate (PET), polypropylene (PP), or polyamide (PA); preferably biaxially oriented polyester (BOPET) or biaxially oriented polypropylene (BOPP), with a thickness of 6-50 μm. The inorganic oxide coating is at least one of aluminum oxide and silicon oxide, and has a thickness of 5-50 nm.

[0036] The present invention will now be described in detail with reference to specific embodiments. It should be noted that these embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments based on the above description of the present invention.

[0037] Unless otherwise stated, all raw materials involved in this invention are available through conventional commercial means. The following examples are used to further illustrate the invention, but should not be construed as limiting the scope of protection of the invention.

[0038] (1) Material preparation and characterization Example 1: Preparation of a single-molecule bifunctional modifier (PEG-Gly) Glycine (4.70 g, 62.5 mmol) was dissolved in 150 mL of MES buffer at pH 5.5, and N-hydroxysuccinimide (NHS, 7.18 g) and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC·HCl, 12.0 g) were added. The mixture was stirred at room temperature for 30 minutes to prepare a glycine active ester (Gly-OSu) solution.

[0039] Monomethoxy polyethylene glycolamine (PEG-NH2, Mn=2000, 100.0 g, 50.0 mmol) was dissolved in 350 mL of MES buffer at pH 5.5. The above Gly-Osu solution was added dropwise with stirring, and the pH was adjusted to 7.5 with 0.1 mol / L sodium hydroxide solution. The reaction was carried out at room temperature for 4 hours. Thin-layer chromatography (TLC) was performed using ninhydrin reagent until the starting material spots essentially disappeared.

[0040] The reaction solution was transferred to a dialysis bag with a molecular weight cutoff (MWCO) of 1000 Da, dialyzed with deionized water for 3 days, and then freeze-dried to obtain a white solid product, PEG-Gly. It was characterized by ¹H NMR (D₂O) (see [link to product description]). Figure 3 The presence of a characteristic peak of glycine methylene at δ=4.1 ppm confirms the successful synthesis of the target structure PEG-NH-CO-CH2-NH2, i.e., PEG-Gly.

[0041] Example 2: Preparation of modified montmorillonite (PEG-Gly-MMT) 5.0 g of sodium-based montmorillonite (Na-MMT) was dispersed in 45 g of deionized water and sonicated for 30 minutes to obtain a homogeneous suspension. 0.25 g of PEG-Gly prepared in Example 1 was added, and the pH was adjusted to 4 with 0.1 mol / L dilute hydrochloric acid. The mixture was mechanically stirred at 80 °C for 5 hours. After the reaction, the mixture was centrifuged, washed with water, and dried to obtain modified montmorillonite powder (PEG-Gly-MMT).

[0042] Characterization was performed using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Figure 4 and Figure 5 The sheet diameter is approximately 810.331 nm, the average thickness is approximately 4 nm, and the aspect ratio is approximately 203 (≥200). The powder was redispersed to prepare a 1 wt% aqueous dispersion, and the turbidity was measured to be 148 NTU. No significant sedimentation was observed after standing for 120 days.

[0043] Comparative Example 1: Two-step preparation of modified montmorillonite (Gly / PEG-MMT) Following a method similar to Example 2, but replacing the PEG-Gly modifier with 0.25 g of glycine, the mixture was centrifuged, washed, and dried to obtain intercalated modified montmorillonite powder (Gly-MMT). The Gly-MMT powder was redispersed in water to prepare a 1 wt% dispersion, and 0.25 g of PEG-NH2 was added as a dispersant. The mixture was stirred at 60°C for 3 h to obtain a two-step modified montmorillonite dispersion (Gly / PEG-MMT).

[0044] Comparative Example 2: Following a similar method to Example 2, but replacing the PEG-Gly modifier with 0.25g of PEG-NH2, with all other treatments remaining the same, a modified PEG-MMT dispersion was obtained.

[0045] Comparative Example 3: Following the same intercalation modification method as in Example 2, but replacing the PEG-Gly modifier with 0.25 g of glycine, Gly-MMT was obtained. It was then redispersed in water without adding any dispersant to prepare a 1 wt% Gly-MMT dispersion.

[0046] Comparative Example 4: Without adding any intercalating agent or dispersant, a Na-MMT dispersion was obtained by following a similar treatment method to Example 2.

[0047] Characterization of modified montmorillonite: a. Aspect ratio The modified inorganic layered material powder was diluted with deionized water to 0.1 g / L, and then applied dropwise to the surface of a silicon wafer using a pipette. The wafer was then dried in a freeze dryer.

[0048] The dried silicon wafers were sputter-coated with gold and then tested using a scanning electron microscope (SEM, JSM-7900F, Nippon Electron Ltd.) at an accelerating voltage of 5kV and a magnification between 5000 and 50000 to obtain the sheet diameter of the inorganic layered material.

[0049] b. Turbidity The obtained modified inorganic layered material dispersion was diluted to 1 wt% and tested using a turbidity meter (TID-POM-100B).

[0050] c. Dispersion stability The obtained modified inorganic layered material dispersion was diluted to 1 wt%, then poured into a 20 mL sampling bottle, and the time of sedimentation was recorded.

[0051] Specific performance indicators are listed in Table 1: Preparation method and performance indicators of surface-modified inorganic layered materials *Note: Because the dispersion settles immediately, the turbidity test cannot be completed, hence the label "cannot be measured".

[0052] Table 1 shows that the PEG-Gly-MMT prepared by the method of the present invention (Example 1) is superior to the traditional two-step method (Comparative Example 1) in terms of aspect ratio, turbidity, and dispersion stability. The intercalation process mainly determines the aspect ratio of the modified inorganic layered material, while the dispersion process mainly affects its aqueous stability. The single-molecule bifunctional modifier of the present invention achieves simultaneous improvement in aspect ratio and dispersion stability by avoiding site competition. Compared with samples that only underwent dispersion (Comparative Example 2), only underwent intercalation (Comparative Example 3), and were unmodified (Comparative Example 4), this further confirms that achieving both high aspect ratio and high dispersion stability simultaneously depends on the synergistic effect of intercalation and dispersion, and the present invention provides an efficient modification route for this purpose.

[0053] (2) Preparation of aqueous coating liquid for high barrier coating Unless otherwise stated, the high-barrier aqueous coating liquids used in the embodiments and comparative examples of this invention are prepared according to the general methods described below.

[0054] The composition of the high-barrier coating aqueous coating liquid includes: aqueous film-forming resin, modified inorganic layered material, crosslinking agent and solvent.

[0055] Raw material description: Waterborne film-forming resin: composed of waterborne polyurethane and polyvinyl alcohol. The waterborne polyurethane is HP-1208 produced by Runchang Chemical. The polyvinyl alcohol is PVA-117 produced by Kuraray.

[0056] Crosslinking agent: γ-aminopropyltriethoxysilane.

[0057] Preparation steps of aqueous coating liquid for high-barrier coating: (1) Preparation of polyurethane emulsion (solution A): HP-1208 and a mixed solvent (deionized water:ethanol mass ratio = 9:1) were mixed in a reactor and stirred at 500 r / min for 30 minutes at room temperature to form a homogeneous emulsion. The mass fraction of waterborne polyurethane in the emulsion was controlled to be 8%.

[0058] (2) Preparation of polyvinyl alcohol solution (solution B): Polyvinyl alcohol PVA-117 and deionized water are mixed in another reactor and pre-dispersed at 200 r / min for 1 hour at room temperature. Then, the temperature is raised to 90℃ and stirring is continued for 6 hours until completely dissolved to form a homogeneous and transparent solution. The mass fraction of polyvinyl alcohol in the solution is controlled to be 8%.

[0059] (3) Preparation of crosslinking agent hydrolysate (C solution): γ-aminopropyltriethoxysilane and a mixed solvent (deionized water:ethanol mass ratio = 9:1) are mixed in a reactor and stirred at 100 r / min for 30 minutes at room temperature to pre-hydrolyze it and form a homogeneous and transparent solution. The mass fraction of silane coupling agent in this solution is controlled to be 5%.

[0060] (4) Mixing and blending: Transfer solution A and solution B to the same reactor and stir for 1 hour. Then, add 1 wt% of the modified / unmodified inorganic layered material aqueous dispersion and continue stirring for 2 hours to ensure uniform dispersion. Finally, add solution C, deionized water, and ethanol, and continue stirring for 30 minutes to obtain the final high-barrier aqueous coating solution. The total solids (i.e., waterborne polyurethane, polyvinyl alcohol, crosslinking agent, and modified / unmodified inorganic layered material) in the final high-barrier aqueous coating solution is controlled to be 5 wt%. In the solvent, the mass ratio of deionized water to ethanol is approximately 18:1.

[0061] (3) Preparation method of high barrier membrane Using BOPET film with an alumina coating (initial WVTR ~2.4 g / (m²·day), OTR ~2.0 cc / (m²·day)) as the substrate, an aqueous coating solution was applied to the coating surface using a microgravure coating process, controlling the wet film coating amount to 10 g / m². 2 After drying at 100℃, the coating is cured at 50℃ for 24 hours. The coating thickness after drying is about 0.5 μm, resulting in a high-barrier film.

[0062] The mass percentages of waterborne polyurethane, polyvinyl alcohol, crosslinking agent, and modified / unmodified inorganic layered materials in the total solids of the high-barrier coating aqueous coating liquid in Examples 3-5 and Comparative Examples 5-13 are shown in Table 2. In Examples 3-5, PEG-Gly-MMT in the modified montmorillonite dispersion prepared in Example 2 was used as the modified inorganic layered material composition in the aqueous coating liquid. In Examples 3-5, the modified montmorillonite accounted for 1 wt%, 3 wt%, and 5 wt% of the total solids of the coating, respectively.

[0063] In Comparative Examples 5-7, Gly / PEG-MMT of the dispersion-modified montmorillonite prepared in Comparative Example 1 was used as the modified inorganic layered material composition in the aqueous coating liquid. In Comparative Examples 5-7, the modified montmorillonite accounted for 5 wt%, 10 wt%, and 15 wt% of the total solids of the coating, respectively.

[0064] Comparative Examples 8-10 used Na-MMT of the unmodified montmorillonite dispersion prepared in Comparative Example 4 as the inorganic layered material composition of the aqueous coating liquid. In Comparative Examples 8-10, montmorillonite accounted for 5 wt%, 10 wt%, and 15 wt% of the total coating solids, respectively.

[0065] Comparative Example 11 uses PEG-MMT of the dispersion-modified montmorillonite prepared in Comparative Example 2 as the modified inorganic layered material composition of the aqueous coating liquid, wherein the modified montmorillonite accounts for 5 wt% of the total solids of the coating.

[0066] Comparative Example 12 uses Gly-MMT of the intercalated modified montmorillonite dispersion prepared in Comparative Example 3 as the modified inorganic layered material composition of the aqueous coating liquid, wherein the modified montmorillonite accounts for 5 wt% of the total solids of the coating.

[0067] Comparative Example 13, a pure resin coating containing no inorganic layered materials, served as a blank control group.

[0068] (4) Test method The performance of the high-barrier membrane prepared by this invention was tested and characterized by the following methods: a. Optical performance testing The light transmittance and haze of the film were measured using a DIFFUSION M57D haze meter from the UK, in accordance with the national standard GB / T2410-2008 "Determination of light transmittance and haze of transparent plastics".

[0069] b. Gas barrier performance test Oxygen permeability: The oxygen permeability tester was used by Mocon OX-TRAN 2 / 28HR, and the test was conducted according to GB / T19789-2005 "Test for Oxidation Permeability of Plastic Films and Sheets for Packaging Materials - Coulomb Test Method".

[0070] Water vapor transmission rate: The water vapor transmission rate tester was used by MOCON AQUATRAN 3 / 38A, USA, according to GB / T 21529-2008 "Determination of water vapor transmission rate of plastic films and sheets - electrolytic sensor method", and the test was conducted at a temperature of 40℃ and a relative humidity of 90%.

[0071] The contents of waterborne polyurethane, polyvinyl alcohol, crosslinking agent, and modified / unmodified inorganic layered materials in the coatings of Examples 3-5 and Comparative Examples 5-13, as well as the corresponding performance test results of the high-barrier films, are shown in Table 2.

[0072] The results of Examples 3-5 show that the PEG-Gly-MMT prepared using the present invention can significantly improve the barrier performance of the high-barrier membrane. As the amount of modified inorganic layered material added increases from 1 wt% to 5 wt%, the WVTR decreases to 0.47 g / (m²·day), the OTR decreases to 0.24 cc / (m²·day), while the transmittance remains at 90.1% and the haze is 3.4%, demonstrating excellent overall performance.

[0073] The comparison shows that the material of the present invention (Example 5) performs far better than the conventional two-step material (Comparative Example 5) with the same amount of additive, even reaching a barrier level that the latter requires three times the amount of additive (Comparative Example 7) to approach, and its optical properties (haze, transmittance) are significantly superior. Comparative Examples 8-12 show that the material without effective synergistic modification has limited barrier enhancement and seriously impairs optical performance. Comparative Example 13 demonstrates that the barrier properties of pure resin coatings are insufficient.

[0074] In summary, this invention integrates intercalation and dispersion functions into a single molecule, employing a one-step process to prepare an inorganic layered material with high exfoliation strength and excellent dispersion stability. This material can construct a highly efficient labyrinthine barrier structure in coatings with low addition amounts, thereby achieving a significant breakthrough in barrier performance while maintaining high optical performance, and possesses important industrial application value.

[0075] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. It should be noted that for those skilled in the art and any person skilled in the art, any equivalent substitutions or changes made to the technical solution and inventive concept of the present invention without departing from the overall concept of the present invention, as well as any changes and improvements made, should also be considered within the scope of protection of the present invention.

Claims

1. A single-molecule bifunctional modifier, characterized in that: The molecular structure includes: The intercalation functional end is derived from a protonable amino acid residue, wherein the amino acid is at least one of glycine, lysine, serine, aspartic acid, and glutamic acid. It can carry a positive charge under acidic conditions, i.e., it has protonated amino groups, and can exchange ions with the negative charge of layered silicate sheets; The dispersing functional end is a hydrophilic polymer segment, wherein the hydrophilic polymer segment is at least one of polyethylene glycol chain, polyacrylic acid chain, polystyrene sulfonate chain or polyphosphate chain, and the number average molecular weight is 300~5000. The intercalation functional end and the dispersion functional end are covalently connected by amide bonds or ester bonds.

2. A method for preparing a single-molecule bifunctional modifier, characterized in that: Includes the following steps: (1) Activate the carboxyl group of amino acids to obtain an amino acid active ester intermediate; the amino acid is at least one of glycine, lysine, serine, aspartic acid, and glutamic acid; (2) The amino acid active ester intermediate is condensed with terminal amino polyethylene glycol or terminal amino polyacrylic acid to form amide bonds or ester bonds.

3. A modified inorganic layered material, characterized in that: Includes the following steps: (1) Disperse the inorganic layered material in deionized water and then subject it to ultrasonic treatment; (2) Add the monomolecular bifunctional modifier as described in claim 1 or 2, adjust the pH to 4-5, and then react at 60-90℃ for 4-8 hours to obtain the modified inorganic layered material.

4. A high-barrier coating composition, characterized in that: By weight percentage, it contains the following components: (1) Waterborne film-forming resin: 90-97%; (2) Crosslinking agent: 2-5%; (3) The modified inorganic layered material according to claim 3: 1-5%.

5. The high-barrier coating composition according to claim 4, characterized in that: The aqueous film-forming resin is at least one of aqueous polyurethane, aqueous acrylic resin, or polyvinyl alcohol.

6. The high-barrier coating composition according to claim 4 or 5, characterized in that: The crosslinking agent is a silane coupling agent.

7. An aqueous coating liquid, characterized in that: The aqueous coating liquid is prepared by combining the high-barrier coating composition according to any one of claims 4-6 with a solvent; wherein, by weight percentage, the high-barrier coating composition is 3-8% and the solvent is 92-97%.

8. The aqueous coating liquid according to claim 4, characterized in that: By weight percentage, the solvent contains the following components: (1) Deionized water: 90-100%; (2) The alcohol solvent is 5-10%, and the alcohol solvent is at least one of ethanol and isopropanol.

9. A high-barrier membrane, comprising: Polymer substrate; An inorganic oxide coating is located on the surface of the polymer substrate; A high-barrier coating is formed on the surface of the inorganic oxide coating, wherein the high-barrier coating is formed by coating with the aqueous coating liquid of claim 7 or 8 and then curing.

10. The high-barrier membrane according to claim 9, characterized in that, The polymer substrate is polyethylene terephthalate (PET), polypropylene (PP), or polyamide (PA); preferably biaxially oriented polyester (BOPET) or biaxially oriented polypropylene (BOPP), with a thickness of 6-50 μm. The inorganic oxide coating is at least one of aluminum oxide and silicon oxide, and has a thickness of 5-50 nm.

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