Compostable, degradable, paper-based system for seedling and container and method of making same

Abstract

The application discloses a compostable and degradable seedling paper base system and container and a preparation method thereof, and belongs to the technical fields of horticultural seedling containers, paper base forming and biodegradable barrier coating. The system integrates a paper fiber container, an anti-blocking drainage structure and a polyhydroxyaliphatic acid ester-based biodegradable barrier coating. In view of the industry pain point that traditional containers are difficult to maintain wet strength and degradation, the scheme designs a directional failure zone, which ensures excellent wet resistance and structural stability during seedling period, and significantly improves root penetration efficiency and compost disintegration speed after transplanting. Compared with conventional full coverage technology, the system effectively solves the problems of orifice plugging and water accumulation and mold growth, realizes precise timing control of functions from protection to degradation. The product does not contain fluorides, meets the strict ecological compliance requirements, and achieves excellent seedling quality and environmental safety with better material utilization.

Description

Technical Field

[0001] This invention belongs to the technical field of horticultural seedling containers, paper-based molding and biodegradable barrier coatings, and particularly relates to compostable and biodegradable seedling paper-based systems and containers and their preparation methods. Background Technology

[0002] Existing seedling containers mainly include plastic seedling cups, pots, plug trays, and fiber-based seedling pots. Plastic containers have high strength and good water resistance, but after use, they often have substrate and agricultural input residues attached to them, resulting in high recycling and cleaning costs and a poor recycling chain, easily forming long-term solid waste. Paper fiber-based containers have the potential for regeneration and degradation, but under seedling conditions such as high-frequency watering, spraying, and bottom irrigation, the fiber network is prone to water absorption and softening, wet strength decay, edge cracking, and damage during transportation. If a full-coverage high-barrier coating is used to enhance water resistance, it may form a root-blocking interface after transplanting, restricting root penetration, and the container's disintegration in soil or compost environments is slow to begin.

[0003] Several technical approaches have been developed to address the issues of moisture retention and post-transplanting degradation in paper-based seedling containers:

[0004] 1. Seedling pot approach based on thermally bonded paper mesh: For example, in the disclosed plant seedling pot solution, plant-derived fibers are mixed with a certain proportion of synthetic thermoplastic fibers and thermally bonded into a paper mesh. If necessary, the paper mesh is perforated by mechanical or electrical discharge to improve root penetration. This approach relies on the paper mesh pores and perforations to achieve root penetration. However, its material system contains synthetic thermoplastic fibers, and its moisture resistance is usually inversely related to the degree of pores or perforations.

[0005] 2. A route based on paper anti-corrosion or wet-strength cross-linking with the creation of "locally perishable zones": For example, in publicly available paper pot solutions for seedling transplanting, the paper as a whole contains anti-corrosion treatment components capable of cross-linking with cellulose. Simultaneously, locally perishable zones are formed through differential temperature treatment or patterned inhibition of the reaction. This allows the paper pot to maintain a certain wet strength during the seedling stage, while after transplanting, the locally perishable zones preferentially take effect to promote cracking and root emergence. This route is centered on cellulose cross-linking anti-corrosion and typically requires a specific anti-corrosion treatment system and differentiated heat treatment equipment. Furthermore, the formation mechanism of its "locally perishable zones" mainly depends on the differences in the anti-corrosion reaction of the fiber substrate itself.

[0006] 3. Approaches to improve water and moisture resistance based on impregnation or admixture of fiber-based pots: For example, EP3247195B1 discloses a plant growth container solution using biodegradable fibers as the base material and combining polyvinyl alcohol (PVOH) / polyvinyl acetate (PVAc) with a wax system to achieve a balance between moisture retention and biodegradability. For example, KR20120021764A discloses a solution using cellulose fibers to form the pot, adding a wet strength agent (WSA), alkyl ketone dimer (AKD), and water-soluble wax, and spraying a polylactic acid (PLA) solution onto the surface and perforating all sides of the pot. This approach emphasizes improving the overall performance of the pot, but it is limited by formulation and structural constraints in simultaneously addressing issues such as "drainage hole blockage and water accumulation" and "rapid disintegration and root penetration after transplanting."

[0007] 4. Non-paper-based biomass molding and surface latex spraying route: For example, in the disclosed biodegradable basin scheme, biomass such as rice straw and coconut coir are mixed and molded as the matrix, and latex is sprayed on at least one side to improve molding strength and water resistance. The matrix and coating system of this route are different from those of paper fiber containers, and the water resistance of the sprayed latex and the coordination with subsequent degradation also require additional window design.

[0008] 5. Technology Transfer of Paper-Based Barrier Coatings in the Packaging Field: In the field of paper-based barrier coatings, disclosed solutions include routes for forming paper-based barrier coatings using polyhydroxyalkanoates (PHA) aqueous dispersions, and routes for nano-sizing PHA particles to form aqueous coating systems. For example, CN112867766A and WO2020036843A1 disclose coating systems based on PHA aqueous dispersions and their coating film-forming methods on paper-based substrates. These solutions mainly focus on the waterproof, oil-proof, and barrier properties of paper-based materials, as well as repulping and recycling pathways. Their focus differs significantly from the usage sequence of seedling containers, which involves "moisture retention under repeated watering conditions—root penetration after transplanting—rapid disintegration in soil or compost environments."

[0009] 6. Coffee Grounds-Related Seedling Material Routes: Existing publicly available solutions utilize coffee grounds through staged fermentation, combined with microbial agents and binders to form "nutrient pots" or molded structures, replacing peat and achieving natural degradation; for example, US20100216909A1 discloses a system for sowing and seedling cultivation and its biodegradable functional container design. This route uses coffee grounds molded structures or nutrient pots as its core, unlike solutions that use stabilized coffee grounds as a component of the seedling substrate module and work in conjunction with a paper-based container structure.

[0010] Furthermore, seedling containers come in a variety of forms: seedling cups and pots are suitable for single-seedling cultivation and transplanting with the seedling in the cup; seedling trays are suitable for standardized tray management and automated handling; and seedling bags are suitable for seedlings and scenarios requiring larger volumes of substrate. Existing technologies often optimize for a single form and lack a unified "structure-material-process" solution that can be reused across different forms. This leads to companies needing to repeatedly develop and validate their products when expanding their product lines, making it difficult to establish a unified compostable and biodegradable disposal pathway.

[0011] Meanwhile, seedling containers also face engineering problems such as "drainage hole blockage and water accumulation" in practical applications: if drainage holes are pre-formed before coating, the coating is prone to bridging or shrinking at the hole opening, causing partial blockage; if bottom irrigation or high-frequency watering is used, water accumulation will induce substrate hypoxia and disease risk. The above problems require the barrier coating, drainage structure and post-transplanting failure triggering mechanism to be designed collaboratively within the same system.

[0012] Therefore, there is an urgent need for a unified paper-based seedling system for cups, pots, trays, and bags: a system that provides necessary water resistance, moisture retention, and structural stability during the seedling stage, while reducing the risk of drainage hole blockage and water accumulation; and a system that enables controllable cracking, root penetration, and easy composting after transplanting through a designable failure-triggered structure and material porosity strategy, thereby simultaneously resolving the temporal contradiction between "reliability during the seedling stage" and "end-of-life degradation or disposal friendliness". Summary of the Invention

[0013] This invention provides a compostable and biodegradable seedling paper-based system and its preparation method. Specifically, the compostable and biodegradable seedling paper-based system includes a seedling paper-based container, a drainage and ventilation structure, a polyhydroxyalkanoate-based biodegradable barrier coating, and a directional failure zone. The seedling paper-based container is selected from one or more of seedling cups, seedling pots, seedling trays, and seedling bags. The seedling paper-based container includes a paper fiber-based container body, which has side walls and a bottom and forms a cavity for accommodating the seedling substrate.

[0014] The drainage and ventilation structure is disposed in at least one area of ​​the bottom or side wall for forming a drainage channel or ventilation channel during the seedling stage, and the drainage and ventilation structure is selected from one or more of drainage holes, ventilation holes, slits, grooves and guide channels; wherein, when the drainage and ventilation structure includes drainage holes or ventilation holes, the hole wall or hole edge area of ​​the drainage hole or ventilation hole is an uncoated area or a weakly coated area, and the hole opening is not continuously sealed by the polyhydroxy fatty acid ester-based biodegradable barrier coating.

[0015] The polyhydroxyalkanoate-based biodegradable barrier coating is disposed on the inner or outer surface of the paper fiber-based container body. The polyhydroxyalkanoate-based biodegradable barrier coating is formed by coating an aqueous coating composition containing polyhydroxyalkanoates and then drying it into a film to provide water or moisture barrier retention during the seedling stage.

[0016] The directional failure zone is located in at least one area of ​​the sidewall or bottom, and the directional failure zone is an uncoated area, a weakly coated area, or a coated area containing hydrophilic porous components. The uncoated area is the area not covered by the polyhydroxyalkanoate-based biodegradable barrier coating; the weakly coated area is the area where the ratio of the dry film coating amount per unit area of ​​the polyhydroxyalkanoate-based biodegradable barrier coating in this area to the dry film coating amount per unit area of ​​the adjacent coated area is >0 and ≤0.60, or the ratio of the average coating thickness of the polyhydroxyalkanoate-based biodegradable barrier coating in this area to the average coating thickness of the adjacent coated area is >0 and ≤0.60, for example, the ratio can be 0.05, 0.10, or 0.125. The ratios are 0.15, 0.20, 0.25, 0.30, 0.40, 0.50, or 0.60, etc.; the ratio of dry film coating amount per unit area is obtained by applying the same masking pattern as the container to a flat paper-based sample prepared under the same batch, formula, and process conditions, and converting the mass difference before and after coating of each zone to the zone area; the ratio of average coating thickness is obtained by preparing cross-sectional samples of the weakly coated area and adjacent coated areas, measuring the thickness of each area using a thickness gauge or micro-thickness measurement method, and taking the average value. After transplanting or entering the soil or composting environment, the directional failure zone triggers the porosity, cracking, or reduced continuity of the polyhydroxyalkanoate-based biodegradable barrier coating, allowing water, microorganisms, and roots to enter or penetrate through the directional failure zone, thereby promoting the disintegration and biodegradation of the paper fiber-based container body.

[0017] The aqueous coating composition comprises a second polymer and an inorganic filler.

[0018] The paper fiber-based container body is a pulp molding part or a paperboard folded or rolled part; the paper fiber raw material is selected from one or more of wood pulp, bamboo pulp, sugarcane pulp, hemp pulp, rice and wheat straw pulp, reed pulp, sisal pulp, kenaf pulp, cotton linter pulp, and waste paper pulp, wherein the waste paper pulp is selected from one or more of newspaper-based recycled fiber pulp, corrugated cardboard box recycled fiber pulp, and office waste paper recycled fiber pulp; and the paper fiber-based container body contains lignin or lignin derivatives, the amount of which is added is 0.1wt% to 30wt% based on oven-dry fiber, for example, it can be 0.1wt%, 0.5wt%, 1wt%, 3wt%, 5wt%, 8wt%, 10wt%, 12wt%, 15wt%, 18wt%, 20wt%, 25wt%, 28wt%, or 30wt%, etc.; the lignin derivative is selected from one or more of alkali lignin, lignin sulfonate, oxidized lignin, esterified lignin, and etherified lignin.

[0019] The polyhydroxyalkanoate is selected from short-chain polyhydroxyalkanoates, medium- and long-chain polyhydroxyalkanoates, or copolymer polyhydroxyalkanoates formed from monomers that form short-chain polyhydroxyalkanoates and medium- and long-chain polyhydroxyalkanoates. The short-chain polyhydroxyalkanoate is selected from one or more of poly-3-hydroxybutyrate, poly-3-hydroxybutyrate-co-4-hydroxybutyrate, and poly-3-hydroxybutyrate-co-3-hydroxyvalerate. The medium- and long-chain polyhydroxyalkanoates are selected from one or more of poly-3-hydroxyhexanoate, poly-3-hydroxyheptanoate, poly-3-hydroxyoctanoate, poly-3-hydroxynonanoate, poly-3-hydroxydecanoate, poly-3-hydroxyundecanoate, poly-3-hydroxydodecanate, poly-3-hydroxytetrate, poly-3-hydroxytetradecanoate, poly-3-hydroxypentadecanate, poly-3-hydroxyhexadecanoate, poly-3-hydroxyhexadecanoate, poly-3-hydroxyheptadecanoate, and poly-3-hydroxyoctadecanoate.

[0020] The aqueous coating composition further comprises a second polymer, which is an aliphatic polyester or an aliphatic-aromatic copolyester; the aliphatic polyester or aliphatic-aromatic copolyester is formed by polycondensation or ring-opening polymerization of one or more of the following monomers: lactic acid, lactide, glycolic acid, glycolide, ε-caprolactone, succinic acid, adipic acid, sebacic acid, terephthalic acid, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, and diethylene glycol. Furthermore, the dry basis amount of the second polymer is 0 to 0.60 times the dry basis mass of the polyhydroxyalkanoate in the aqueous coating composition, for example, 0 times, 0.05 times, 0.10 times, 0.125 times, 0.20 times, 0.28 times, 0.30 times, 0.33 times, 0.40 times, 0.50 times, 0.55 times, or 0.60 times, etc.

[0021] The aqueous coating composition includes an inorganic filler selected from one or more of talc, kaolin, silica, calcium carbonate, mica, bentonite, diatomaceous earth, titanium dioxide, zinc oxide, and magnesium hydroxide. The dry basis amount of the inorganic filler is 0.05 to 0.55 times the dry basis mass of the polyhydroxyalkanoate in the aqueous coating composition, for example, 0.05, 0.10, 0.11, 0.125, 0.14, 0.15, 0.20, 0.25, 0.30, 0.33, 0.40, 0.43, 0.45, 0.50, or 0.55 times.

[0022] The polyhydroxyalkanoate-based biodegradable barrier coating is a single-layer or multi-layer structure; when it is a multi-layer structure, it includes a paper-sensitive base coating and a polyhydroxyalkanoate barrier top coating, wherein the paper-sensitive base coating contains a water-soluble polysaccharide or a cellulose derivative, the water-soluble polysaccharide being selected from one or more of modified starch, dextrin, and maltodextrin, and the cellulose derivative being selected from one or more of sodium carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose; and the total dry film thickness of the polyhydroxyalkanoate-based biodegradable barrier coating on one side is 8 μm to 55 μm, for example, it can be 8 μm, 10 μm, 12 μm, 15 μm, 18 μm, 20 μm, 22 μm, 25 μm, 30 μm, 35 μm, 40 μm, 45 μm, 50 μm, or 55 μm, etc.

[0023] The directional failure region is selected from one or more of the following: strip-shaped, lattice-shaped, grid-shaped, ring-shaped, spiral-shaped, microporous, open-pore, and slotted regions. The area fraction of the directional failure region in the total area of ​​the inner or outer surface actually coated on the paper fiber-based container body is 1% to 35%, for example, it can be 1%, 3%, 5%, 8%, 10%, 12%, 15%, 18%, 20%, 25%, 30%, or 35%. When the polyhydroxyalkanoate-based biodegradable barrier coating of the directional failure region contains a hydrophilic porous component, the hydrophilic porous component is selected from one or more of water-soluble polysaccharides, cellulose derivatives, water-soluble polyethers, water-soluble lactam polymers, and water-soluble inorganic salts. The water-soluble polysaccharide is selected from one or more of modified starch, dextrin, and maltodextrin. The cellulose derivative is selected from one or more of sodium carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose. The water-soluble polyether includes polyethylene glycol. The water-soluble lactam polymer includes polyvinylpyrrolidone, and the water-soluble inorganic salt is selected from one or more of sodium chloride, potassium chloride, potassium sulfate, and sodium bicarbonate; and the dry basis addition amount of the hydrophilic porous component is 0.05 to 0.40 times the dry basis mass of the polyhydroxyalkanoate-based biodegradable barrier coating in the directional failure region, for example, it can be 0.05 times, 0.10 times, 0.15 times, 0.20 times, 0.25 times, 0.30 times, 0.35 times, or 0.40 times, etc.

[0024] The periphery of the drainage hole or vent hole constitutes at least a portion of the directional failure zone to reduce the risk of the orifice being blocked by the coating and causing water accumulation.

[0025] The system includes a seedling support module, which is selected from one or more of a seed module, a seedling substrate module, and a tray module. The seedling substrate module contains an organic substrate component, selected from one or more of compressed coconut coir, peat, pulp substrate, compost substrate, and bark humus; and the seedling substrate module contains stabilized coffee grounds, which are obtained through aerobic composting and sieving; the mass fraction of the stabilized coffee grounds, on a dry basis, is 10wt% to 40wt%, for example, 10wt%, 15wt%, 18wt%, 20wt%, 25wt%, 30wt%, 35wt%, or 40wt%, etc.; the seedling substrate module also contains a pH buffer component, selected from one or more of dolomite powder, calcium carbonate, and wood ash; and the seedling substrate module contains a substrate conditioning component, selected from one or more of perlite, vermiculite, zeolite, and pumice.

[0026] The present invention also provides a method for preparing the above-mentioned seedling paper-based system, the method comprising the following steps:

[0027] Step 1. Preparation of paper fiber-based container body: The paper fiber-based container body is prepared by pulp molding process or paperboard folding and rolling process;

[0028] Step 2. Preparation of the coated container body: Aqueous dispersion of polyhydroxyalkanoate, inorganic filler, or aqueous dispersion of polyhydroxyalkanoate, inorganic filler and a second polymer aqueous dispersion are mixed and dispersed to obtain an aqueous coating composition; the aqueous coating composition is coated on the inner or outer surface of the paper fiber-based container body and dried to form a film to obtain a coated container body with a polyhydroxyalkanoate-based biodegradable barrier coating;

[0029] Step 3. Forming a directional failure zone: The predetermined area of ​​the coated container body obtained in Step 2 is masked or locally thinned, or a hydrophilic porous component is introduced into the predetermined area to obtain a coated container body with a directional failure zone;

[0030] Step 4. Forming a drainage and ventilation structure: A drainage and ventilation structure is formed on the coated container body with directional failure zone obtained in Step 3 to obtain a seedling paper-based container;

[0031] Step 5. Assembly: Assemble the seedling paper-based container obtained in Step 4 with the seedling substrate module, seed module and tray module into a set or complete the packaging to obtain the seedling paper-based system.

[0032] In step 1 of the preparation method, when using a pulp molding process, paper fiber raw materials are dispersed with water to form a paper fiber pulp. The paper fiber pulp is pumped to a molding die and dehydrated under vacuum before demolding to obtain a wet container body blank. The wet container body blank is further dehydrated and dried, and then structurally shaped by hot pressing or densification. When using a cardboard folding and rolling process, cardboard is selected, and after die-cutting to obtain an unfolded sheet, it is crimped and folded or rolled into shape. Water-based starch adhesive is used as an overlap bonding agent, and then the shape is completed under hot pressing conditions.

[0033] In step 2, before coating the aqueous coating composition, a paper-friendly undercoating composition comprising water-soluble polysaccharides or cellulose derivatives is coated on the inner or outer surface of the paper fiber-based container body obtained in step 1 and dried to form a paper-friendly undercoating; subsequently, the aqueous coating composition is coated on the paper fiber-based container body or the paper-friendly undercoating.

[0034] In step 3, the predetermined area includes a periphery ring area of ​​the drain hole or vent hole, and the width of the ring area is 1.0 mm;

[0035] In step 4, the drainage and ventilation structure is formed by any of the following methods: punching, laser drilling or needle punching the coated container body to form drainage holes or ventilation holes; or forming a slit at the bottom of the container and pressing a guide groove on the outer surface of the bottom.

[0036] This invention also provides a method for seedling cultivation and easy composting disposal using a compostable and biodegradable seedling paper-based system. The method includes placing the seedling substrate and seeds or seedlings in a seedling paper-based container for seedling management; after seedling cultivation, transplanting the seedling paper-based container together with the substrate and the plant into a soil environment, a home composting environment, or an industrial composting environment, allowing water, microorganisms, and roots to enter or penetrate through the directional failure zone, and promoting the porosity, cracking, or reduced continuity of the polyhydroxyalkanoate biodegradation barrier coating, while simultaneously causing the paper fiber-based container body to gradually disintegrate and undergo biodegradation, thereby achieving easy composting disposal of the whole.

[0037] The seedling paper-based container and its polyhydroxyalkanoate-based biodegradable barrier coating, under controlled composting conditions at 58±2℃, showed an ultimate aerobic biodegradation rate of ≥90% after 180 days, as measured by GB / T 19277.1-2025, and a disintegration rate of ≥90% after 84 days of composting, as measured by ISO 20200:2023. Furthermore, the compost product of the seedling paper-based container and its polyhydroxyalkanoate-based biodegradable barrier coating was mixed with standard test soil at a dry basis mass fraction of 5wt% as the treatment group, with the standard test soil without added compost product serving as the blank control. Plant emergence and early growth experiments were conducted according to ISO 11269-2:2012, and the plant emergence rate and plant biomass of the treatment group were both ≥90% of the corresponding values ​​of the blank control.

[0038] The total organic fluorine content of the seedling paper-based container and its polyhydroxyalkanoate-based biodegradable barrier coating, as measured according to EN 14582:2016, is <5 mg / kg, which is the detection limit.

[0039] Compared with the prior art, the following significant advantages can be obtained by using the present invention:

[0040] Synergistic optimization of barrier and degradation timing control: This invention provides necessary moisture barrier protection during the seedling stage through a polyhydroxyalkanoate-based coating. Simultaneously, through the design of directional failure zones (uncoated, weakly coated, or with hydrophilic components), it successfully resolves the contradiction between the tendency of traditional paper-based containers to absorb moisture and collapse during the seedling stage and their difficulty in degradation and root penetration after transplanting. The container of this invention exhibits excellent structural stability during the wet seedling stage, while achieving efficient root penetration after transplanting and rapidly disintegrating in a composting environment.

[0041] Excellent rhizosphere microenvironment and anti-mold properties: By creating pores after coating or avoiding coating treatment on the pore edges, this invention effectively avoids the coating material blocking the drainage holes, ensuring smooth drainage and ventilation during seedling cultivation, significantly reducing the risk of mold growth, and guaranteeing a high survival rate of seedlings.

[0042] Extremely high ecological safety and environmental friendliness: The systems of this invention all exhibit extremely high biodegradability, and the compost products are non-toxic to plant growth. Furthermore, tests have shown that the total organic fluorine content meets environmental protection requirements, completely avoiding the pollution risks of perfluorinated and polyfluoroalkyl substances (PFAS), providing a truly green and safe seedling solution for modern agriculture. Attached Figure Description

[0043] Figure 1 This is a schematic cross-sectional view of the compostable and biodegradable seedling paper-based system described in this invention.

[0044] In the diagram, 1-seedling; 2-compostable and biodegradable paper-based seedling system; 3-seedling substrate; 4-directional failure zone; 5-drainage and ventilation structure; 6-polyhydroxyalkanoate-based biodegradable barrier coating; 7-paper fiber-based container body. Detailed Implementation

[0045] 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.

[0046] Figure 1 The diagram shows a cross-sectional perspective of the compostable and biodegradable seedling paper-based system 2 described in this invention in a seedling application state, clearly revealing the interaction between the seedling 1 growing in the seedling substrate 3 and its container. The container is a composite structure consisting of an inner paper fiber-based container body 7 that provides physical support and an outer polyhydroxyalkanoate-based biodegradable barrier coating 6 that provides water and moisture resistance. The bottom is provided with a drainage and ventilation structure 5. The diagram highlights the pre-set directional failure zone 4 located on the side wall and visually depicts the roots of the seedling 1 penetrating this area, verifying its function of guiding the roots out after transplanting and triggering the overall disintegration of the container.

[0047] Main reagents and raw materials:

[0048] The main reagents and raw materials used in the embodiments and comparative examples of this invention are shown in Table 1.

[0049] Table 1. Main reagent and raw material names, brands / specifications, and manufacturers:

[0050]

[0051] Main analytical and testing instruments:

[0052] The main analytical instruments used in the embodiments and comparative examples of this invention are shown in Table 2.

[0053] Table 2 mainly analyzes the names, brands / models, and manufacturers of the testing instruments:

[0054]

[0055] Main testing standards:

[0056] Moisture determination: Performed in accordance with standard GB / T 462-2023 "Determination of moisture content in analytical samples of paper, paperboard and pulp".

[0057] Environmental pretreatment: Sample treatment and environmental control were carried out in accordance with the standard GB / T 10739-2023 "Standard atmospheric conditions for the treatment and testing of paper, paperboard and pulp samples".

[0058] Tensile strength: The test was performed in accordance with standard GB / T 12914-2018 "Determination of tensile strength of paper and paperboard - constant speed tensile test (20 mm / min)". The tensile speed was 20 mm / min, and the sample cutting method and clamping distance were as described in Application Example 1.

[0059] Cobb water absorption: Tested according to standard ISO 535:2023.

[0060] Water vapor transmission rate: Tested according to ASTM F1249-25.

[0061] Biodegradability: Performed in accordance with standard GB / T 19277.1-2025 "Determination of final aerobic biodegradability of materials under controlled composting conditions by means of determination of carbon dioxide released - Part 1: General method".

[0062] Disintegration level: Performed in accordance with standard ISO 20200:2023.

[0063] Plant emergence and early growth: Performed in accordance with standard ISO 11269-2:2012.

[0064] Total organic fluorine (TOF) determination: performed in accordance with standard EN 14582:2016.

[0065] Preparation of newspaper-based recycled fiber pulp:

[0066] Step 1. Remove plastic inserts, staples, and other impurities from waste newspapers, then shred them and place them in a pulper. Add 50°C warm water and soak for 2 hours. Adjust the pulp mass fraction to 12wt%, add 1.0wt% sodium hydroxide (based on oven-dry fiber) and 0.2wt% deinking agent (based on oven-dry fiber, non-ionic surfactant type deinking agent), and shred for 30 minutes at a pulper speed of 1200rpm to obtain shredded pulp.

[0067] Step 2. The fragmented pulp obtained in Step 1 is subjected to flotation deinking at 25°C with an air flow rate of 2.0 L / min and a flotation time of 15 minutes. After flotation, it is washed three times with deionized water (after each wash, it is dewatered to a pulp mass fraction of 10 wt%). The pH value of the pulp is adjusted to 7.0, and the pulp mass fraction is finally concentrated to 20 wt% to obtain newspaper-based regenerated fiber pulp.

[0068] Preparation of PBAT aqueous dispersion:

[0069] Step 1. Take PBAT resin particles and add dichloromethane to prepare a 15wt% solution, and dissolve it at 35℃ with magnetic stirring (400rpm) for 180 minutes; separately take deionized water and add SDS to prepare a 3wt% aqueous solution; add the PBAT solution to the SDS aqueous solution at a rate of 8mL / min, and simultaneously use a high shear disperser to shear emulsify at 12000rpm for 20 minutes to obtain an emulsion.

[0070] Step 2. The emulsion from Step 1 was rotary evaporated at 40°C and 15 kPa absolute pressure for 45 minutes to remove dichloromethane. Then, a 10 kDa ultrafiltration membrane was used in a stirred ultrafiltration system for ultrafiltration concentration and water washing replacement. The operating pressure was 0.25 MPa and the stirring speed was 300 rpm. Deionized water was used for replacement three times (each replacement volume was 1.0 times the initial dispersion volume). Finally, the solid content was adjusted to 50 wt% to obtain the PBAT aqueous dispersion.

[0071] Preparation of PLA aqueous dispersions:

[0072] Step 1. Take PLA resin particles and add dichloromethane to prepare a 15wt% solution, and dissolve it at 35℃ with magnetic stirring (400rpm) for 180 minutes; separately take deionized water and add SDS to prepare a 3wt% aqueous solution; add the PLA solution to the SDS aqueous solution at a rate of 8mL / min, and simultaneously use a high shear disperser to shear emulsify at 12000rpm for 20 minutes to obtain an emulsion.

[0073] Step 2. The emulsion from Step 1 was rotary evaporated at 40°C and 15 kPa absolute pressure for 45 minutes to remove dichloromethane; then, a 10 kDa ultrafiltration membrane was used in a stirred ultrafiltration system for ultrafiltration concentration and water washing replacement. The operating pressure was 0.25 MPa and the stirring speed was 300 rpm. Deionized water was used for replacement three times (each replacement volume was 1.0 times the initial dispersion volume). Finally, the solid content was adjusted to 45 wt% to obtain an aqueous dispersion of PLA.

[0074] Preparation of aqueous dispersions of PBS:

[0075] Step 1. Take PBS resin particles and add dichloromethane to prepare a 15wt% solution, and dissolve it at 35℃ with magnetic stirring (400rpm) for 180 minutes; separately take deionized water and add SDS to prepare a 3wt% aqueous solution; add the PBS solution to the SDS aqueous solution at a rate of 8mL / min, and simultaneously use a high-shear disperser to shear emulsify at 12000rpm for 20 minutes to obtain an emulsion.

[0076] Step 2. The emulsion from Step 1 was rotary evaporated at 40°C and 15 kPa absolute pressure for 45 minutes to remove dichloromethane. Then, a 10 kDa ultrafiltration membrane was used in a stirred ultrafiltration system for ultrafiltration concentration and water washing replacement. The operating pressure was 0.25 MPa and the stirring speed was 300 rpm. Deionized water was used for replacement three times (each replacement volume was 1.0 times the initial dispersion volume). Finally, the solid content was adjusted to 50 wt% to obtain an aqueous PBS dispersion.

[0077] Preparation of fine talc powder:

[0078] Step 1. Select high whiteness talc ore blocks, coarsely crush them with a jaw crusher, and then send them to an air jet mill for ultrafine crushing to obtain coarse talc powder.

[0079] Step 2. Control the particle size distribution of the coarse talc powder obtained in Step 1 by adjusting the speed of the classifying wheel, collect the fine powder and detect it using a laser particle size analyzer to obtain the median particle size D. 50 It is a talc filler with a thickness of 5.0 μm.

[0080] Preparation of stabilized coffee grounds:

[0081] Step 1. Collect fresh coffee grounds and record the wet weight as 20 kg. Take a representative sample and determine the initial moisture content according to GB / T 462-2023. Adjust the moisture content of the coffee grounds to 60% by spraying deionized water into the coffee grounds and mixing thoroughly. Take another representative sample and use an elemental analyzer to determine the total organic carbon and total nitrogen and calculate the carbon-nitrogen ratio (C / N). The initial C / N ratio of the coffee grounds used in this example is 25:1, so no additional carbon or nitrogen source is needed. Add aerobic fermentation agent (solid powder, added at 0.5 wt% of the wet weight of the coffee grounds) and compost. The wet weight of the compost pile is 20 kg. Turn the pile every 3 days. If the moisture content deviates from 60% after turning, add deionized water and mix thoroughly to correct the deviation. Continue fermentation for 30 days until mature, i.e., the temperature of the compost pile is continuously <45℃ for 72 hours to obtain mature coffee grounds.

[0082] Step 2. Dry the fermented coffee grounds obtained in Step 1 in an 80℃ forced-air drying oven for 6 hours until the moisture content is 10wt%. Then, sieve the grounds using a standard sieve separator (sieve mesh size 2.0mm), and collect the undersize material to obtain the median particle size (D). 50 Stabilized coffee grounds with a diameter of 1.0 mm and an electrical conductivity (EC) of 1.2 mS / cm were used; the electrical conductivity (EC) was measured using a conductivity meter at 25°C with a 1:5 (m / v) water extract.

[0083] Preparation of simulated compost mixtures:

[0084] Step 1. According to the ISO 20200 standard formula, weigh the following components on a dry weight basis: 40% sawdust, 30% rabbit feed, 10% corn starch, 5% sucrose, 4% corn oil, 1% urea and 10% well-rotted compost inoculum to obtain the dry-based mixed components.

[0085] Step 2. Thoroughly mix the dry-based mixture obtained in Step 1, and add deionized water to adjust the moisture content of the mixture to 58%, thus obtaining a simulated compost mixture.

[0086] Preparation of composting containers with ventilation holes:

[0087] Step 1. Select a 20L polypropylene (PP) plastic bucket and mark a circle around the bucket wall 10cm from the bottom to obtain the container to be punched.

[0088] Step 2. Drill 5mm diameter ventilation holes evenly along the marked line on the container to be drilled in Step 1. The center distance between adjacent holes is 3cm. This container is used to simulate an aerobic composting environment to ensure natural ventilation and oxygen supply during the composting process, resulting in a composting container with ventilation holes.

[0089] Example:

[0090] General container specifications and manufacturing process: Unless otherwise specified, the inner diameter of the top opening of the seedling cup is 70mm, the inner diameter of the bottom opening is 50mm, and the height is 80mm; the inner diameter of the top opening of the seedling pot is 95mm, the inner diameter of the bottom opening is 65mm, and the height is 90mm; the unfolded width of the seedling bag is 150mm and the effective height is 180mm; the seedling tray is a 32-cell tray, with an inner diameter of 45mm at the top opening of each cell and a cell depth of 50mm. During pulp molding, the mass fraction of paper fiber pulp is adjusted to 1.5 wt%, and the pulp temperature is 25℃. Vacuum molding is performed in a pulp molding machine with a vacuum degree of -60 kPa and a molding time of 25 s. After demolding, the wet preform of the container body is placed between two layers of polyester filter cloth and pressed for 60 seconds at 1.0 MPa under room temperature pressing mode (press plate temperature 25℃) in a hot press forming machine to reduce the moisture content of the wet preform to 60 wt%. After drying in an 80℃ forced-air drying oven for 4 hours, it is transferred to 105℃ to dry to constant weight (the difference between two adjacent weighings is <0.2%). Subsequently, it is hot-pressed in a hot press forming machine at 160℃ and 2.0 MPa for 30 seconds to complete densification and shaping, thus obtaining the paper fiber-based container body.

[0091] Preparation and coating parameters of the aqueous coating composition: Unless otherwise specified, the solid content of the PHA aqueous dispersion is 42 wt%, and the solid content of the second polymer aqueous dispersion is 50 wt%. The PHA aqueous dispersion, the second polymer aqueous dispersion (if any), and the inorganic filler are added to a high-shear disperser according to the dry solids ratio of the example, dispersed at 6000 rpm for 10 minutes, then stirred at 1000 rpm for 5 minutes and allowed to stand for degassing for 15 minutes to obtain the aqueous coating composition. The three-dimensional seedling paper-based container sample is coated using an air spray method. Coating is performed as follows: The container is fixed on a rotatable clamp, and the inner and outer surfaces of the container are sprayed separately using a spray gun with a nozzle diameter of 0.8mm under a spraying pressure of 0.20MPa. Before each spraying, the container mass m0 is weighed, and immediately after spraying, the mass m1 is weighed. The wet coating amount per coat is calculated as G = (m1-m0) / A based on the actual spread area A of the corresponding surface of the container, and the wet coating amount per coat is controlled to be 30g / m². After each spraying, the container is dried in hot air at 60℃ for 5 minutes. The spraying is repeated until the target dry film thickness is achieved. The dry film thickness is determined using the thickness difference method: The thickness of the container sidewalls before and after coating is measured using a paper and paperboard thickness meter. Ten points are measured for each sample and the average is taken. Unless otherwise stated, the "coating dry film thickness" mentioned in this specification refers to the total dry film thickness of a single-sided coating (for multi-layer structures, it is the sum of the dry film thickness of the paper-adhesive base coating and the barrier coating on that single side). If double-sided coating is used, the dry film thickness of a single-sided coating is half of the thickness difference.

[0092] Description of drainage holes and hole edge areas: In each embodiment, the drainage holes and / or vent holes are formed by punching, laser drilling, or needle punching after the barrier coating has formed a film, so that the hole openings are not continuously sealed by the coating, and the hole walls and edges are uncoated fiber areas; the uncoated areas are achieved by masking to avoid coating, specifically by pasting a heat-resistant masking material on a predetermined area before coating and peeling off the masking material after drying to ensure that the area is not covered by the water-based coating composition; wherein the heat-resistant masking material is polyimide (PI) heat-resistant tape or an equivalent heat-resistant masking film, the polyimide heat-resistant tape has a thickness of 0.06 mm, a width of 10 mm, a heat resistance rating of 260°C, and can be peeled off without residue after drying; the weak coating areas are achieved by patterning to control the number of coatings and / or the amount of wet coating per coat. When the single wet coating amount is kept consistent, a thickness ratio of 0.50 corresponds to two coatings in the weak coating area and four coatings in the adjacent coating area, and a thickness ratio of 0.25 corresponds to one coating in the weak coating area and four coatings in the adjacent coating area. When the number of coatings is kept consistent, a coating amount ratio of 0.40 corresponds to a single wet coating amount in the weak coating area set to 40% of that in the adjacent coating area, and a coating amount ratio of 0.125 corresponds to a single wet coating amount in the weak coating area set to 12.5% ​​of that in the adjacent coating area. When a ring-shaped weak coating area is set on the outer side of the hole edge, a positioning template is used to form a concentric ring-shaped shielding / thinning pattern around the predetermined hole position. The positioning template is a positioning template made of metal or hard resin material and has positioning holes that match the positions of drainage holes or vent holes. This ring-shaped area is part of the directional failure area.

[0093] After transplanting or when placed in soil or composting environments, the directional failure zone triggers the porosity, cracking, or reduced continuity of the PHA-based biodegradable barrier coating, allowing moisture, microorganisms, and roots to enter or penetrate through the directional failure zone, thereby promoting the disintegration and biodegradation of the paper fiber-based container body. Herein, "porosity" as used in this specification refers to the process by which the barrier coating forms interconnected pores or channels under the action of moisture, the dissolution of hydrophilic porosimetric components, and / or microorganisms, thus reducing the continuity of the coating.

[0094] Example of the lower limit of inorganic filler: In the implementation of the low addition amount of inorganic filler, the dry solid mass ratio of inorganic filler to PHA is 1:20 (that is, the inorganic filler is 0.05 times the dry basis mass of PHA).

[0095] Example 1:

[0096] Container body formulation (based on oven-dry fiber): bleached softwood pulp board to bleached hardwood pulp board in a mass ratio of 7:3, and alkali lignin added at 10 wt% of oven-dry fiber mass.

[0097] PHA-based biodegradable barrier coating formulation (on a solids basis): The dry solids mass ratio of PHBV aqueous dispersion, PBAT aqueous dispersion and talc is 8:1:1 (i.e., the inorganic filler is 0.125 times the dry weight of PHA).

[0098] Structural and process parameters: The container shape is a seedling cup; the dry film thickness of the coating is 18μm; the side wall is set with strip-shaped directional failure zones, the area fraction of which is 20%, and the strip-shaped directional failure zones are shielded to avoid coating to form uncoated areas; the drainage holes are formed by punching after the barrier coating is formed, with a hole diameter of 2.0mm, and there are 4 drainage holes at the bottom.

[0099] Example 2:

[0100] Container body formulation (based on oven-dry fiber): The mass ratio of newspaper-based recycled fiber pulp to bleached softwood pulp board is 1:1, and the amount of alkali lignin added is 5 wt% of the oven-dry fiber mass.

[0101] PHA-based biodegradable barrier coating formulation (on a solids basis): The dry solids mass ratio of PHB aqueous dispersion to silica is 20:11 (i.e., the inorganic filler is 0.55 times the dry mass of PHA, verifying the upper limit of filler addition).

[0102] Structural and process parameters: The container shape is a seedling pot; the dry film thickness of the coating is 12μm; a grid-like directional failure zone is set on the side wall, with an area fraction of 15%, which is a local thinning area (thickness ratio 0.25); drainage holes are formed by punching after film formation, with a hole diameter of 2.5mm, and there are 6 drainage holes at the bottom.

[0103] Example 3:

[0104] Container body formulation (based on oven-dry fiber): bleached softwood pulp board, with alkali lignin added at 30 wt% of oven-dry fiber mass (verification of the upper limit of lignin content).

[0105] PHA-based biodegradable barrier coating formulation (on a solids basis): The dry solids mass ratio of PHBH aqueous dispersion, PBAT aqueous dispersion and calcium carbonate is 3:1:1.

[0106] Structural and process parameters: The container is in the form of a seedling bag; the dry film thickness of the coating is 22 μm; the area fraction of the directional failure zone is 35%, containing a composite hydrophilic porous component of modified starch and polyvinylpyrrolidone, wherein the dry basis addition of modified starch is 0.15 times, and the dry basis addition of PVP is 0.05 times (the total dry basis addition of the hydrophilic porous component is 0.20 times); the drainage holes are formed by punching after film formation, with a pore diameter of 3.0 mm, and there are 8 drainage holes at the bottom; and 12 ventilation holes with a pore diameter of 1.5 mm are provided on the side wall.

[0107] Example 4:

[0108] Container body formulation (based on oven-dry fiber): bleached hardwood pulp board, no lignin added.

[0109] PHA-based biodegradable barrier coating: multilayer structure. The paper-sensitive base coating is modified starch (5wt% solution); the top coating is a mixture of P34HB aqueous dispersion and calcium carbonate (7:3). The total dry film thickness of a single-sided coating is 55μm.

[0110] Structural and process parameters: The container shape is a seedling tray; the failure area is a dot-matrix weak coating area at the bottom of the holes (coating amount per unit area ratio of 0.125), with an area fraction of 8%; the drainage holes are formed by punching after film formation, with one drainage hole at the bottom of each hole, and the hole diameter is 2.0 mm.

[0111] Example 5:

[0112] Container body formulation (based on oven-dry fiber): bleached softwood pulp board and bleached hardwood pulp board in a 1:1 ratio, with alkali lignin added at 0.1 wt%.

[0113] PHA-based biodegradable barrier coating formulation (on a solids basis): dry solids mass ratio of PHBH aqueous dispersion, PBAT aqueous dispersion and talc powder is 5:3:2.

[0114] Structural and process parameters: The container shape is a seedling cup; the dry film thickness of the coating is 8μm; the failure area is a spiral weak coating area (thickness ratio 0.50) with an area fraction of 1%; the drainage holes are formed by punching after film formation, with a hole diameter of 2.0mm, and there are 4 drainage holes at the bottom.

[0115] Example 6:

[0116] Container body formulation (based on oven-dry fiber): bleached softwood pulp board to bleached hardwood pulp board 7:3, alkali lignin added 12wt%.

[0117] PHA-based biodegradable barrier coating formulation (on a solids basis): The dry solids mass ratio of PHBH aqueous dispersion, PBAT aqueous dispersion and silica is 7:2:1.

[0118] Structural and process parameters: The container shape is a seedling cup; the dry film thickness of the coating is 15μm; there is a grid-like directional failure zone (area fraction 12%, thickness ratio 0.50); ​​the drainage holes are formed by punching after film formation, with a hole diameter of 2.0mm, and there are 4 drainage holes at the bottom; and a ring-shaped weak coating area with a width of 1.0mm (thickness ratio 0.50) is set on the outer side of each drainage hole edge, and the ring-shaped weak coating area is included in the 12% area fraction of the grid-like directional failure zone.

[0119] Example 7:

[0120] The formulation of the container body (based on oven-dry fiber): the mass ratio of rice and wheat straw pulp, unbleached bamboo pulp board and unbleached hemp pulp board is 7:2:1, and the amount of alkali lignin added is 15wt%.

[0121] PHA-based biodegradable barrier coating formulation (based on solids): The dry solids mass ratio of PHBV aqueous dispersion, PLA aqueous dispersion and kaolin is 6:2:2 (i.e., the second polymer PLA is 0.33 times and the inorganic filler is 0.33 times).

[0122] Structural and process parameters: The container shape is a seedling cup; the dry film thickness of the coating is 20μm; a strip-shaped directional failure zone with an area fraction of 18% is set on the side wall, and this area is an uncoated area; the drainage holes are formed by punching after film formation, with a hole diameter of 2.0mm, and there are 4 drainage holes at the bottom.

[0123] Example 8:

[0124] Container body formulation (based on oven-dry fiber): the mass ratio of cotton linter pulp to bleached hardwood pulp board is 1:1, and the amount of alkali lignin added is 5wt%.

[0125] PHA-based biodegradable barrier coating formulation (based on solids): The dry solids mass ratio of PHBH aqueous dispersion, PBS aqueous dispersion and mica powder is 5:2.5:1.5 (i.e., the second polymer PBS is 0.50 times and the inorganic filler is 0.30 times).

[0126] Structural and process parameters: The container shape is a seedling pot; the dry film thickness of the coating is 30μm; the bottom wall is set with a dot matrix directional failure area with an area fraction of 10%, which is a weak coating area (coating amount ratio 0.4); the drainage holes are formed by punching after film formation, with a hole diameter of 2.5mm, and there are 6 drainage holes at the bottom.

[0127] Example 9:

[0128] Container body formulation (based on oven-dry fiber): bleached softwood pulp board, with alkali lignin added at 10 wt%.

[0129] PHA-based biodegradable barrier coating formulation (on a solids basis): PHB aqueous dispersion to calcium carbonate mass ratio of 9:1.

[0130] Structural and process parameters: The container shape is a seedling cup; the dry film thickness of the coating is 15μm; the side wall is set with a directional failure zone containing polyethylene glycol, with an area fraction of 15%; the dry PEG content in the directional failure zone formulation is 0.05 times the dry PHA content of the zone (to verify the lower limit of hydrophilic components); the drainage holes are formed by punching after film formation, with a pore diameter of 2.0mm, and there are 4 drainage holes at the bottom.

[0131] Example 10:

[0132] Container body formulation (based on oven-dry fiber): bleached hardwood pulp board, with alkali lignin added at 8 wt%.

[0133] PHA-based biodegradable barrier coating formulation (on a solids basis): PHBV aqueous dispersion to talc powder in a mass ratio of 8:2.

[0134] Structural and process parameters: The container shape is a seedling cup; the dry film thickness of the coating is 18μm; the side wall is set with a directional failure zone containing sodium chloride (NaCl) with an area fraction of 20%; the dry basis of NaCl in the directional failure zone formulation is 0.40 times the dry basis mass of PHA in that zone (to verify the upper limit of hydrophilic components); the drainage holes are formed by punching after film formation, with a pore diameter of 2.0mm, and there are 4 drainage holes at the bottom.

[0135] Comparative example:

[0136] Comparative Example 1:

[0137] Key features: The container body formulation and process are exactly the same as in Example 1, but no PHA-based biodegradable barrier coating is applied.

[0138] Comparative Example 2:

[0139] Key features: The formulation and molding process of the container body are exactly the same as those in Example 1; the coating material is a PVOH aqueous solution with a PVOH mass fraction of 10 wt%, and glyoxal crosslinking agent (40 wt% aqueous solution) is added so that the amount of glyoxal is 5 wt% of the dry basis mass of PVOH; the process sequence is "punching holes first, then coating", that is, first punching holes at the bottom of the container to form drainage holes with a diameter of 2.0 mm and a number of drainage holes of 4, then spraying a PVOH coating on the inner and outer surfaces of the container, drying with hot air at 60°C for 5 minutes, and then curing at 120°C for 10 minutes to form a crosslinked coating, with a single-sided dry film thickness of 15 μm; because the coating is sprayed after pre-forming holes, the orifice is prone to bridging by the coating liquid, which can cause the orifice to shrink or be partially blocked after drying.

[0140] Comparative Example 3:

[0141] Key features: The formulation and molding process of the container body are exactly the same as those in Example 1; the coating material is PE emulsion with a solid content of 55wt%, which is diluted to 30wt% with deionized water and then sprayed onto the inner and outer surfaces of the container. The coating is formed by hot air drying at 80℃ for 10 minutes, and the single-sided dry film thickness is 18μm; the drainage holes are formed by punching after film formation, with a hole diameter of 2.0mm and a number of 4 drainage holes; the side walls and bottom of the container are fully covered with coating, and no directional failure zone is set.

[0142] Comparative Example 4:

[0143] Key features: The formulation and molding process of the container body are exactly the same as those in Example 1; the formulation of the barrier coating is exactly the same as that in Example 1 and is a full coverage coating with a single-sided dry film thickness of 18 μm; no drainage holes are provided at the bottom of the container, and no directional failure zones are provided on the side walls and bottom.

[0144] Comparative Example 5:

[0145] Key features: The container body formulation and molding process are exactly the same as those in Example 1; the barrier coating formulation is exactly the same as that in Example 1 and is a full coverage coating with a single-sided dry film thickness of 18 μm; the drainage holes are formed by punching after film formation, with a hole diameter of 2.0 mm and a number of 4 drainage holes; no directional failure zones are provided on the sidewalls and bottom.

[0146] Comparative Example 6:

[0147] Key feature: The amount of lignin added to the container body is 40 wt% of the oven-dried fiber mass (exceeding the 30 wt% upper limit specified in this invention).

[0148] Comparative Example 7:

[0149] Key feature: The dry basis amount of silica (inorganic filler) in the coating is 0.70 times the dry basis mass of PHA (exceeding the upper limit of 0.55 times limited by this invention).

[0150] Comparative Example 8:

[0151] Key feature: The area fraction of the directional failure zone in the total coating area of ​​the container is 50% (exceeding the 35% upper limit set by this invention).

[0152] Comparative Example 9:

[0153] Key features: The dry film thickness of the coating is only 5 μm (< the lower limit of 8 μm specified in this invention), and the other parameters are the same as in Example 1.

[0154] Comparative Example 10:

[0155] Key features: The dry basis addition of polylactic acid (PLA, the second polymer) in the coating is 0.80 times (exceeding the upper limit of 0.60 times limited by the present invention), and the rest is the same as in Example 7.

[0156] Comparative Example 11

[0157] Key features: The dry basis addition of modified starch (hydrophilic porous component) in the coating of the directional failure zone is 0.60 times, and the rest is the same as in Example 3.

[0158] Application example:

[0159] Application Example 1: Stability and collapse resistance test of wet structures.

[0160] Experimental Description: This experiment aims to simulate the effects of high-frequency spraying and a moist substrate environment on the mechanical properties of seedling containers during seedling cultivation, and to verify the stability of the wet structure under different formulations and process parameters. Containers prepared in Examples 1 to 10 and Comparative Examples 1 to 11 were selected as test objects. Ten containers from each group were used as parallel samples (n=10). Table 3 shows the arithmetic mean of the ten parallel samples. Before the experiment, all test containers were pretreated for 24 hours under standard atmospheric conditions of 23℃ and 50% relative humidity. The seedling substrate (dry basis) was composed of 72wt% compressed coconut coir, 18wt% stabilized coffee grounds, and 5wt% perlite, with 5wt% dolomite powder added as a pH buffer to achieve a substrate pH of 6.2. The median particle size (D) of the stabilized coffee grounds was... 50 The thickness was 1.0 mm. Each group of containers was filled with a moist substrate adjusted to a moisture content of 65%, with the filling height uniformly controlled to 90% of the container depth to ensure consistent substrate bulk density for each sample group. The containers were then placed in an artificial climate chamber with a temperature of 25℃, relative humidity of 90%, and a light cycle of 12 hours / 12 hours. During the test, 60 mL of deionized water was evenly sprayed onto each container daily at 9:00 AM using a spray nozzle with an orifice diameter of 0.8 mm, a spray angle of 60°, and a flow rate calibrated to 120 mL / min using a graduated cylinder. The nozzle was positioned 20 cm above the substrate surface, with each spray cycle lasting 30 seconds, simulating daily watering operations, for a period of 30 days. On day 30, the container was removed and its appearance and deformation were observed, and its resistance to softening and collapse was scored (1-5 points, where 5 points indicates no obvious deformation and 1 point indicates severe collapse). The container was then emptied of the matrix and gently washed with deionized water to remove surface contaminants. It was then soaked in deionized water at 23°C for 24 hours to reach saturation. Standard specimens (15 mm wide, 100 mm effective gauge length) were cut from the non-directional failure zone of the sidewall. The wet tensile strength was measured using an electronic tensile testing machine at a tensile speed of 20 mm / min and compared with the dry tensile strength of the same group of samples under standard atmospheric conditions to calculate the wet tensile strength retention rate.

[0161] Table 3. Results of wet structure stability and collapse resistance tests:

[0162]

[0163] Experimental Results Analysis: As can be seen from the experimental data in Table 3, the paper-based seedling system designed in this invention exhibits significant differentiated performance under humid conditions. The wet tensile strength retention rates of Examples 1 to 10 range from 55.2% to 88.5%, and the softening and collapse resistance scores are all above 4.1, indicating that even with a lignin content as low as 0.1 wt% (Example 5) or no lignin added (Example 4), the container can still meet the basic seedling support requirements through reasonable hot-pressing densification and coating protection. Examples 7 and 8 used non-wood fiber raw materials such as rice and wheat straw pulp and cotton linter pulp, combined with PLA or PBS as the second polymer, and still maintained high wet strength retention rates of 72.3% and 75.6%, respectively, proving the universality of this system for different fiber raw materials and biodegradable polymers. In contrast, Comparative Example 1, lacking barrier coating protection, experienced rapid disintegration of the fiber network under moisture erosion, with a retention rate of only 8.5%, completely unable to support the seedling process. Although Comparative Example 6 exhibited a high wet strength retention rate (82.1%) due to the addition of 40 wt% lignin, the excessive lignin caused the container body to become brittle, making it prone to brittle fracture under simulated handling and spray impact, resulting in a collapse resistance score of only 3.0. Comparative Example 9 reduced the coating thickness to 5 μm, failing to form an effective barrier, causing the wet strength retention rate to plummet to 32.4%. In Comparative Example 10, the excessive addition of the second polymer (0.80 times) affected film density, leading to impaired wet strength. In Comparative Example 11, the excessive hydrophilic component in the directional failure zone (0.60 times) caused premature water absorption and softening in this area, triggering local structural collapse. The data fully demonstrate the necessity of controlling the lignin content, coating thickness, and hydrophilic component ratio within specific numerical ranges.

[0164] Application Example 2: Drainage ventilation and mildew prevention test.

[0165] Experiment Description: This experiment mainly examines the effects of different drainage hole structures and coating processes on the drainage performance and mold resistance of seedling containers. The experimental subjects include Examples 1 to 10 and Comparative Examples 1 to 11, with 10 containers from each group used as parallel samples (n=10). Table 4 shows the comprehensive judgment of the 10 parallel samples. The experiment was conducted in an artificial climate chamber with environmental conditions set at 28℃ and 85% relative humidity to simulate a high-temperature and high-humidity environment prone to mold growth. At the beginning of the experiment, 100mL of deionized water was poured into each group of containers filled with standard substrate (dry basis: 72wt% compressed coconut coir, 18wt% stabilized coffee grounds, 5wt% perlite, and 5wt% dolomite powder). A stopwatch was used to record the time when water started to flow from the bottom drainage hole and when it stopped dripping, and to observe whether there was any water accumulation. Subsequently, a 20-day routine seedling management phase was implemented, with watering once daily at a fixed time. During the experiment, the coating condition (whether there was bridging or blockage) around the drainage hole at the bottom of the container and the mold growth on the substrate surface were observed and recorded twice a day, morning and evening. The criteria for judging mold were observed with a 10x magnifying glass. If visible hyphae appeared on the substrate surface or the inner wall of the container and the colony area accounted for more than 1% of the total surface area, it was judged as "moldy". If water accumulation lasted for more than 1 hour or the bottom was in a state of water saturation for a long time, it was judged as "bottom water accumulation". If drainage was rapid and there was no long-term stagnant water, it was judged as "smooth drainage and no water accumulation".

[0166] Table 4. Results of Drainage Ventilation and Mildew Prevention Tests:

[0167]

[0168] Analysis of Experimental Results: The experimental results clearly demonstrate the key impact of drainage hole structure design and material formulation on the container microenvironment. Examples 1 to 10 all employed a process of punching holes or avoiding coating the orifices after the barrier coating film was formed. This design effectively ensured unobstructed drainage channels, and most examples exhibited excellent characteristics of smooth drainage, no water accumulation, and no mold growth. Although Examples 9 and 10 introduced strongly hydrophilic components such as polyethylene glycol or sodium chloride into the directional failure zone, because these were controlled within a reasonable range of 0.05-0.40 times, no sidewall leakage or mold growth occurred during the seedling stage. Conversely, Comparative Example 2 used a process of punching holes before coating. During the experiment, it was observed that the coating liquid formed a liquid film bridge at the orifice opening, which, after drying, led to partial or even complete pore size reduction and blockage, resulting in bottom water accumulation and mold growth. Comparative Example 4, lacking any drainage structure, suffered the most severe water accumulation problem, and the substrate rapidly rotted and became moldy. Comparative Examples 1 and 9, lacking effective coating protection (no coating or excessively thin coating), allowed the paper base to absorb water, becoming a breeding ground for mold and leading to severe mold growth on the container walls. Comparative Example 11, due to excessive addition of hydrophilic porous components (0.60 times), experienced water leakage on the container sidewalls during the seedling stage, resulting in persistently damp areas and inducing localized mold growth. This confirms that ensuring the drainage hole walls / edges are uncoated or weakly coated through process control, and strictly controlling the content of hydrophilic components, is crucial for maintaining a healthy rhizosphere microenvironment.

[0169] Application Example 3: Seedling growth and barrier performance test.

[0170] Experimental Description: This experiment aimed to investigate the correlation between the barrier properties (water absorption and moisture permeability) of the coating and the growth indicators of plant seedlings. Tomato (variety Carmello F1) was selected as the indicator plant, and seedlings were sown and raised in containers used in Examples 1-10 and Comparative Examples 1-11. The seedling period was 30 days, and the artificial climate chamber conditions were: 16 hours of light / 8 hours of darkness, light intensity 250 μmol / (m²·s), and day / night temperatures 25℃ / 18℃. No additional fertilizer was applied during the seedling period; nutrients were obtained solely from the substrate. On the 30th day of seedling raising, the survival rate of 30 seedlings in each group was recorded, the average plant height (from the substrate surface to the growing point) was measured, and the above-ground parts were blanched at 105℃ and then dried at 80℃ to constant weight, and the dry weight was measured.

[0171] Simultaneously, physical performance tests were conducted on the coating materials of each group of containers: samples were cut from the non-directional failure area of ​​the sidewall of each group of containers, and the samples were pretreated for 24 hours at 23°C and 50% relative humidity. Cobb 60Water absorption (g / m²) was tested according to ISO 535 standard. Six 100mm × 100mm samples were taken for each group, with a test area of ​​100cm². The water temperature was maintained at 23±1℃, and the absorption time was 60 seconds. The arithmetic mean of the six results was taken. Water vapor transmission rate (WVTR, g / m²·d) was tested according to ASTM F1249-25 using the modulated infrared sensing method. A water vapor transmission rate tester was used at 38℃ and 90% RH, with an effective test area of ​​50cm². Three samples were tested for each group, and the average value was taken. By comparing growth data and barrier data, the specific effects of different coating formulations and thicknesses on seedling cultivation were analyzed.

[0172] Table 5. Results of seedling growth and barrier performance tests:

[0173]

[0174] Experimental Results Analysis: The experimental data revealed a close relationship between the barrier properties of the coating and plant growth. Examples 1 to 10 show the effects of Cobb coatings. 60 With water absorption controlled between 14-44 g / m² and water vapor transmission rate between 320-560 g / m²·d, this moderate barrier property prevented the container from losing water too quickly while ensuring the root system's respiration needs. Therefore, the survival rate of tomato seedlings was consistently above 96.8%, with excellent plant height. Example 6 achieved the lowest Cobb value (14 g / m²) and optimal growth performance through an optimized formula. Comparative Example 1, lacking a coating, experienced extremely rapid water loss (WVTR as high as 980 g / m²·d), and the substrate was frequently under drought stress, resulting in a survival rate of only 75.4% and stunted plants. Comparative Example 9, with an excessively thin coating (5 μm), suffered from a loss of barrier properties, resulting in a Cobb value as high as 95 g / m², which also affected the survival rate (82.5%). Although Comparative Example 3 showed acceptable growth indicators, its extremely low moisture permeability (80 g / m²·d) could lead to root entrapment or root hypoxia risks during long-term seedling cultivation. Comparative Example 10, due to excessive addition of the second polymer, resulted in a discontinuous microstructure of the coating and decreased barrier properties (Cobb = 55 g / m²). Comparative Example 11, due to excessive hydrophilic components, caused excessive moisture absorption by the container sidewalls during the seedling stage (Cobb = 72 g / m²), leading to uneven substrate moisture distribution and affecting the uniformity of seedling growth. This indicates that controlling the coating thickness to 8-55 μm, the filler-to-second polymer ratio to be below 0.60, and the failure zone area to be below 35% are key parameter parameters for ensuring successful seedling cultivation.

[0175] Application Example 4: Root penetration and disintegration test after transplanting.

[0176] Experiment Description: This experiment focuses on evaluating the functional transformation ability of seedling containers after transplanting into the soil environment, specifically, their transformation from "containers during the seedling stage" to "permeable degradable substances in the soil." Forty-five days after transplanting, containers containing tomato seedlings from each group were transplanted as a whole into test troughs filled with horticultural loam (maintained at 65% field capacity), with a soil pH of 6.8 and an organic matter content of 25 g / kg. Ten samples from each group were used for the transplanting experiment. Before transplanting, four 30 mm × 30 mm observation windows were evenly marked on the side wall of each container, with each observation window containing at least a portion of the directional failure zone pattern.

[0177] Thirty days after transplanting, carefully excavate the soil around the container and gently rinse the roots with deionized water using a high-pressure washer at a nozzle distance of 200mm and a spray pressure of 0.5MPa. Take photos of the four observation windows at a fixed shooting distance of 200mm with a ruler placed on the ground, using the same lighting conditions (5500K white light, 1000lx illuminance) and a camera resolution of at least 4000×3000 pixels. Analyze the images using ImageJ software (Version 1.53 or later): convert the images to 8-bit grayscale and perform binarization using the same threshold (Otsu method); in "Particle Analysis," set the minimum particle area to 1.0mm² and exclude edge particles to calculate the root projection area (mm²); the observation area was 900mm². Root penetration rate (%) = root projection area / observation area × 100%. The average of the four windows for each sample was taken, and the average of 10 samples was taken for each group.

[0178] Sixty days after transplanting, the remaining containers were excavated and cleaned again, and the degree of disintegration was scored based on the integrity of the containers.

[0179] 5 points indicates fragmentation and a residual area fraction >2mm <10%;

[0180] A score of 4 indicates obvious cracking and fragmentation, with a residual area fraction >2mm ranging from 10% to 40%.

[0181] 3 points indicates multiple cracks but still retains part of the overall shape; the residual area fraction >2mm is 40%-70%.

[0182] 2 points indicates minor cracking or localized damage; the residual area fraction >2mm is 70%-90%.

[0183] 1 point indicates that the morphology is basically intact, and the residual area fraction >2mm is ≥90%.

[0184] This experiment aims to verify whether the design of directional failure regions can effectively trigger the subsequent degradation process.

[0185] Table 6. Results of root penetration and disintegration tests after transplanting:

[0186]

[0187] Analysis of Experimental Results: The experimental results strongly confirm the core role of directional failure zones in resolving the contradiction between "moisture resistance" and "degradation" timelines. In Examples 1-10, after transplanting, the directional failure zones (whether uncoated, weakly coated, or containing hydrophilic components) rapidly absorbed water, softened, or biodegraded, forming "windows" for root penetration. Examples 3 and 10, containing hydrophilic porous components (modified starch or NaCl), achieved root penetration rates as high as 92.1% and 94.5%, respectively; the grid design of Example 6 also achieved a high penetration rate of 90.5%. Even Example 5 (1%), with the smallest failure zone area, showed significantly better root penetration rate (62.5%) and disintegration score (3.8 points) than Comparative Example 5 (18.7% penetration rate, 2.3 points disintegration score) with full coverage and no failure zone design, demonstrating that even a small amount of failure zone guidance is necessary. Comparative Examples 2 and 3, due to full coating coverage and the hindering properties of the material, showed almost no root penetration (<6%), and the containers remained intact after 60 days. Of particular note is Comparative Example 6. Although its root penetration rate was acceptable, the excessively high lignin content (40%) made the container itself difficult to degrade, resulting in a disintegration score of only 2.5 after 60 days, exhibiting a "penetrating but not disintegrating" state. Comparative Examples 9 and 11, while possessing excellent penetration and disintegration performance, have been previously confirmed to have unsatisfactory seedling performance (wet strength, mildew resistance), failing to meet the requirements for the entire life cycle. Therefore, only the series of Example Examples achieved ideal post-transplanting performance while ensuring seedling performance.

[0188] Application Example 5: Compost biodegradation and disintegration performance test.

[0189] Experimental Description: This experiment aims to comprehensively evaluate the environmental fate of the seedling paper-based system under industrial composting conditions, including its mineralization capacity (biodegradation rate) at the chemical level and its fragmentation capacity (degree of disintegration) at the physical level. Examples 1-10 and Comparative Examples 1-11 were selected as test subjects, with three parallel reactors set up in each group (n=3). The reported results are the arithmetic mean of the three parallel reactors.

[0190] Final aerobic biodegradation rate test: Performed according to GB / T 19277.1-2025 standard. Each container (including the body and coating) was cut into 2cm×2cm fragments and mixed with inoculum (mature compost from an aerobic composting plant, mainly composed of thermophilic bacteria) and filler (vermiculite) at a dry weight ratio of 1:6, adjusting the moisture content to 50%. In a composting reactor at 58±2℃, air (flow rate 80mL / min) with carbon dioxide (CO2) removed by a soda-lime absorption column was continuously introduced. The soda-lime absorption column was filled with 500g. Before each test, a blank reactor was continuously aerated for 60 minutes, and the volume fraction of carbon dioxide in the outlet gas was measured. Timing began after confirming that the volume fraction of carbon dioxide in the outlet gas was ≤0.01%. During the test, the soda-lime was replaced every 24 hours, and the above confirmation steps were repeated to ensure effective removal. During the 180-day testing period, CO2 production was continuously monitored using a compost biodegradation respiration meter system, and the relative biodegradation rate was calculated using microcrystalline cellulose as a reference. The pass standard was ≥90%.

[0191] Disintegration test: Performed according to ISO 20200:2023 standard. A synthetic solid waste matrix was prepared, comprising 40% sawdust, 30% rabbit feed, 10% corn starch, 5% sucrose, 4% corn oil, 1% urea, and 10% well-rotted compost inoculum, resulting in a dry-basis mixture. The container sample to be tested was cut into 25mm × 25mm pieces and pre-dried at 105℃ to constant weight to determine the initial dry weight of the sample. The pieces were then mixed with the synthetic matrix at a wet weight ratio of 1:100 and placed in a vented compost container for disintegration testing. The vented compost container was a polypropylene (PP) plastic drum reactor (20L volume, with 5mm diameter vent holes drilled evenly along the circumference on both sides of the drum wall 10cm from the bottom, with a center-to-center distance of 3cm between adjacent holes). The reactor after sample loading was placed in a forced-air constant temperature chamber at 58±2℃. During the experiment, the mixture was stirred every 7 days, and after weighing, deionized water was added to maintain the moisture content at 58% ± 2%. During stirring, any clumping was checked and broken up to maintain an aerobic environment. On day 84 (12 weeks) of the experiment, the compost was removed, dried at 105℃, and sieved. Residual samples that failed to pass through a 2mm standard sieve were collected and weighed. The degree of disintegration (%) was calculated as: (Initial sample dry weight - Dry weight of residue larger than 2mm) / Initial sample dry weight × 100%. The acceptable standard was a degree of disintegration ≥ 90%.

[0192] Table 7 Composting performance test results:

[0193]

[0194] Experimental Results Analysis: The dual-index test results strongly confirm the excellent composting performance of the material system of this invention. From the disintegration data, Examples 1-10 showed a disintegration rate of 96.8% to 99.5% at the end of the 84-day composting cycle. This means that the container can rapidly break down physically into particles <2mm in the composting environment, almost invisible to the naked eye. Example 6, in particular, achieved a disintegration rate of 99.5%, almost completely disappearing. This is attributed to the synergistic effect of the hygroscopic swelling properties of the paper fiber substrate and the bio-erosion properties of the PHA coating. Regarding the correlation between chemical degradation and physical disintegration, the example group achieved a dual superior performance of "high disintegration + high decomposition," proving that the material not only undergoes physical disintegration but also has a high final aerobic biodegradation rate, thus significantly reducing the probability of forming difficult-to-biodegrade residues. In contrast, the PE coating of Comparative Example 3 had a biodegradation rate of only 0.8% and a disintegration rate of 0.0%, indicating that polyolefin coatings have extremely low biodegradability under controlled composting conditions and are difficult to physically disintegrate, easily resulting in long-term residues. The cross-linked PVOH in Comparative Example 2 had a disintegration rate of only 45.6%, indicating that the chemical cross-linking network hindered the physical fragmentation process of the material, resulting in large residues. Comparative Example 6, with a lignin content as high as 40%, had a rigid benzene ring structure that was extremely difficult for microorganisms to break down, resulting in a disintegration rate of only 58.2% and an unqualified biodegradation rate, exhibiting the characteristics of being "difficult to break down and difficult to degrade".

[0195] Application Example 6: Ecological security testing.

[0196] Experimental Description: To ensure that the container does not release harmful substances into the soil during degradation, this experiment conducted a plant emergence and early growth test on the compost products. Compost products from each group were collected after 180 days of composting in Example 5, air-dried, and ground through a 2mm sieve. Each group's compost products were mixed with standard test soil (LUFA 2.2, sandy loam) at a dry basis weight of 5 wt% to form the treatment group, while the standard test soil without added compost products served as the blank control group.

[0197] The experimental containers were plastic flower pots with a diameter of 90 mm and a depth of 120 mm. Each pot contained 300 g of soil from the treatment group or control group (on a dry basis), and four parallel pots were set up for each treatment.

[0198] The indicator plants selected are two terrestrial higher plants: oats and rapeseed.

[0199] Sow 20 oat seeds per pot and cover them with soil to a depth of 10mm.

[0200] Sow 30 rapeseed seeds per pot and cover them with soil to a depth of 5mm.

[0201] The flowerpots were placed in an artificial climate chamber for 14 days. The cultivation conditions were set as follows: temperature 25℃, relative humidity 70%, light cycle 16 hours / dark cycle, and light intensity 250 μmol / (m²·s). During the cultivation period, deionized water was used to maintain the soil moisture content at 65% of field capacity.

[0202] On day 7 of cultivation, the number of seedlings was recorded and the emergence rate was calculated. On day 14, the aboveground parts were harvested, blanched at 105℃ for 30 minutes, and then dried at 80℃ to constant weight. The aboveground dry biomass was measured. The relative emergence rate (emergence rate of treatment group / emergence rate of control group × 100%) and relative biomass (dry biomass of treatment group / dry biomass of control group × 100%) were calculated.

[0203] Table 8. Results of Ecological Safety Tests (Relative Emergence Rate and Relative Biomass):

[0204]

[0205] Experimental Results Analysis: As shown in Table 8, the samples from Examples 1-10 of this invention performed excellently in the plant ecological safety test. The relative germination rate of all example groups remained above 97.5%, and the relative biomass was above 96.8%. Among them, Example 6 performed best, with a relative germination rate of 99.5% and a relative biomass of 99.0%. These figures are highly similar to those of Comparative Example 1 (relative germination rate 99.2%, relative biomass 98.8%) without any coating, and statistically, there was no significant difference compared to the blank control soil. This fully demonstrates that the PHA-based biodegradable barrier coating and its additives (such as inorganic fillers, trace hydrophilic components, etc.) used in this invention, after sufficient composting and degradation, have no toxic effects on plant growth and do not alter the physicochemical properties of the soil, thus not inhibiting plant development, exhibiting extremely high ecological safety.

[0206] In contrast, the performance of the comparative examples revealed the potential environmental risks of different material systems. Comparative Example 2 (PVOH coating) showed a decrease in relative germination rate and relative biomass to 86.5% and 85.0%, respectively. Combined with the lower disintegration rate (45.6%) in Application Example 5, this is presumably due to incomplete degradation of the cross-linked PVOH, with residual polymer fragments or cross-linking agent intermediates inhibiting seedling root growth. While Comparative Example 3 (PE coating) had a acceptable germination rate (91.0%), its biomass (90.5%) was significantly lower than the example group. This is because PE did not degrade at all (biodegradation rate 0.8%), leading to the accumulation of large amounts of microplastic fragments in the soil, damaging the soil's pore structure and hindering free root extension and nutrient absorption. The data for Comparative Example 6 (high lignin) (92.5% and 91.5%) were also slightly lower, possibly due to the slow degradation of excessive lignin and the allelopathic inhibitory effect of phenolic substances released during degradation on sensitive seedlings in the short term.

[0207] In summary, the present invention achieves excellent barrier and structural performance while demonstrating its environmental friendliness throughout its entire life cycle.

[0208] Application Example 7: Total Organic Fluorine (TOF) Content Test.

[0209] Experimental Description: Addressing the growing concern about perfluorinated and polyfluoroalkyl substances (PFAS) pollution, this experiment followed the oxygen bomb combustion procedure of EN 14582:2016 to test the total organic fluorine (TOF) content of each group of containers to verify their environmental compliance. Mixed samples containing coatings and substrates were randomly cut from the finished containers of Examples 1-10 and Comparative Examples 1-11 and pulverized to a particle size <1 mm using a cryogenic grinder. 0.3 g of the sample was accurately weighed and placed in an oxygen bomb combustion apparatus, charged with 3.0 MPa of high-purity oxygen for complete combustion at a temperature exceeding 1000 °C. The gases produced by combustion were completely absorbed by 10 mL of 0.1 mol / L sodium hydroxide absorbent. After filtration through a 0.22 μm filter membrane, the fluoride ion content was determined using ion chromatography. The ion chromatography conditions were as follows: an anion exchange column of IonPac AS19 (4 mm × 250 mm), a guard column of AG19 (4 mm × 50 mm), isocratic elution with 20 mmol / L KOH, a flow rate of 1.0 mL / min, an AERS 500 (4 mm) suppressor, an injection volume of 25 μL, and a column temperature of 30 °C. A series of fluoride ion standard solutions at concentrations of 0.05 mg / L, 0.10 mg / L, 0.50 mg / L, 1.00 mg / L, and 5.00 mg / L were prepared to establish an external standard curve and calculate the fluoride ion content in the samples. The TOF content was then converted based on the sample mass. Each sample was measured in triplicate, and the average value was taken. A reagent blank was also included. The detection limit of this method was 5 mg / kg. If the result was < detection limit, it was reported as "not detected".

[0210] Table 9. Results of Total Organic Fluorine (TOF) Content Test:

[0211]

[0212] Experimental Results Analysis: The test results showed that the TOF content of all tested samples (including Examples 1-10 and Comparative Examples 1-11) was <5 mg / kg, and was therefore determined to be "not detected". This result has significant environmental implications, confirming that the present invention strictly avoids the use of fluorinated waterproofing agents, fluorinated surfactants, and other organic fluorine compounds during raw material selection and processing. Currently, some pulp molding products on the market often add PFAS-like substances to achieve waterproof and oil-proof performance. However, the present invention achieves excellent barrier properties physically through PHA-based coating technology, completely replacing chemical fluorinated additives. This result indicates that the TOF content of the samples from the present invention is <the detection limit, which helps to meet the relevant market requirements for TOF limits and reduces the potential risk of organic fluorine-related pollution in compost products. This ensures the cleanliness and safety of the final compost products.

[0213] Application Example 8: Validation of the amount of coffee grounds added to stabilize the window.

[0214] This application example aims to verify the formulation parameters of the seedling substrate module and does not involve material or structural variables of the container itself. To control for single variables, this experiment uniformly uses the seedling cup prepared in Example 6, which has the best overall performance, as the container carrier, and does not involve comparisons with other examples or comparative examples.

[0215] Experimental Description: This experiment specifically verified the addition ratio of stabilized coffee grounds in the seedling support module, aiming to determine the optimal substrate formulation range. Five gradient experimental groups were set up, with stabilized coffee grounds accounting for 5%, 10%, 20%, 40%, and 50% of the dry substrate mass. The mass fractions of dolomite powder and perlite in each group were fixed at 5 wt%, with the remainder being compressed coconut coir. Thirty seedling cups filled with the corresponding substrate were prepared for each group (Example 6), and tomatoes (variety Carmello F1) were sown. The seedling environment and management conditions were the same as in Application Example 3. After 30 days of seedling cultivation, the seedling survival rate of each group was counted. Aboveground parts were collected, blanched at 105℃, dried at 80℃, and weighed. Simultaneously, the substrate surface was visually inspected for mold growth (mold determination criteria were the same as in Application Example 2).

[0216] Table 10 Validation results of the amount of stabilized coffee grounds added:

[0217]

[0218] Experimental Results Analysis: Through gradient testing of the substrate formulation, the optimal application window for stabilized coffee grounds can be clearly defined. When the addition amount of stabilized coffee grounds is between 10% and 40%, the tomato seedlings exhibit the best growth, with a survival rate maintained above 97.5% and a high dry weight (1.20-1.25 g / plant), and no mold growth occurs throughout the process. This indicates that within this range, the slow-release nitrogen source provided by coffee grounds and the water retention and aeration properties of coconut coir form a good complement. However, when the addition amount is only 5%, due to insufficient nutrient contribution, the plants are slightly weak, with a dry weight of only 1.05 g / plant. More seriously, when the addition amount increases to 50%, the oil content and high water retention of the coffee grounds themselves lead to a decrease in substrate aeration, and excessive organic matter is prone to secondary fermentation in a humid and hot environment, resulting in mold growth in the substrate. The survival rate drops significantly to 88.0%, and the dry weight also drops to its lowest level. This experimental data scientifically supports the rationale for limiting the content of stabilized coffee grounds to the range of 10%-40%.

[0219] Experimental Results and Analysis:

[0220] Based on the systematic test data from Examples 1-10, Comparative Examples 1-11, and Application Examples 1-8, this invention provides an in-depth analysis of the comprehensive performance and the influence of key parameters of the compostable and biodegradable seedling paper-based system. Experimental results show that by adjusting the composition of the paper fiber-based container body, the formulation of the PHA-based biodegradable barrier coating, and the structural design of the directional failure zone, the core contradiction between "moisture retention during the seedling stage" and "rapid degradation / root penetration after transplanting" in traditional paper-based seedling containers can be effectively resolved.

[0221] Synergistic analysis of wet structural stability and barrier performance:

[0222] Experimental data show that coating formulation and thickness are key factors determining the wet performance of the container. The wet tensile strength retention rates of Examples 1-10 remained between 55.2% and 88.5%, and the softening collapse resistance scores were all above 4.1 points (out of 5), significantly better than Comparative Example 1 (retention rate of 8.5%) without coating and Comparative Example 9 (retention rate of 32.4%) with an excessively thin coating (5 μm).

[0223] (1) Effect of inorganic fillers: An appropriate amount of inorganic filler (0.05-0.55 times) can enhance the density and mechanical modulus of the coating. However, when the amount of inorganic filler added is too high, reaching 0.70 times (Comparative Example 7), the integrity of the PHA continuous phase is destroyed, resulting in a sharp drop in wet tensile strength retention to 35.6%, and the water absorption of Cobb increases to 85 g / m², indicating that the barrier performance is impaired.

[0224] (2) Effect of secondary polymers: Introducing an appropriate amount (0-0.60 times) of secondary polymers (such as PBAT, PLA, PBS) helps improve the film-forming toughness of PHA. However, when its content is too high, reaching 0.80 times (comparative example 10), it may cause phase separation or changes in crystallinity, resulting in a decrease in wet strength retention to 45.8% and a decrease in barrier performance (Cobb value increases to 55 g / m²).

[0225] (3) Effect of lignin: As a natural adhesive and hydrophobic component, lignin helps to improve the rigidity of the container body when added in the range of 0.1wt%-30wt%. However, when the addition amount exceeds 40wt% (Comparative Example 6), although the wet strength retention rate is high (82.1%), the container body becomes brittle, the collapse resistance score decreases (3.0 points), and it seriously hinders subsequent biodegradation.

[0226] The regulatory role of directional failure zones on root penetration and degradation:

[0227] The design of the directional failure zone is the core of realizing the functional transformation after transplanting. In Examples 1-10, the root penetration rate reached more than 62.5% 30 days after transplanting, with the highest reaching 94.5% (Example 10), and the disintegration score was more than 3.8 points at 60 days.

[0228] (1) Failure zone area fraction: When the area fraction is in the range of 1%-35%, it can balance wet strength and penetration performance. When the area fraction is as high as 50% (Comparative Example 8), although the root penetration rate is high, the wet tensile strength retention rate during the seedling stage is only 42.3%, and the collapse resistance is poor (2.1 points), which cannot meet the structural requirements during the seedling stage. On the contrary, in Comparative Examples 4 and 5 without failure zone design, the root penetration rate is extremely low (<20%), and the container is difficult to disassemble.

[0229] (2) Hydrophilic porosilicate components: Introducing 0.05-0.40 times the amount of hydrophilic porosilicate components into the directional failure zone (Examples 3, 9 and 10) can significantly improve root penetration rate (>92%). However, when the amount of hydrophilic components is excessive to 0.60 times (Comparative Example 11), it causes premature moisture absorption and softening of the sidewalls during the seedling stage (Cobb value 72 g / m²) and even leakage, leading to localized mold growth and compromising seedling safety.

[0230] Safety analysis of drainage structure and rhizosphere microenvironment:

[0231] The treatment of drainage holes directly affects rhizosphere health. The example group employed either a "coating before hole formation" or "hole opening avoidance coating" process, ensuring that the drainage hole edges were uncoated or lightly coated, achieving smooth drainage and preventing mold growth. In contrast, Comparative Example 2, which used a "hole-first, coating-later" process, experienced severe mold growth due to water accumulation at the bottom caused by coating bridging and blocking at the hole openings. Furthermore, the compost products in all examples showed a relative impact of over 96% on plant germination rate and biomass, and TOF was not detected, confirming the ecological safety of the system throughout its entire life cycle.

[0232] Trend analysis of changes in the content of key substances:

[0233] Based on the above experimental results, the influence trend of the content changes of the key substances and parameters detailed in this invention on the experimental results is analyzed as follows:

[0234] The influence of lignin content: As the lignin content in the paper fiber-based container increases from 0.1 wt% to 30 wt%, the dry and wet rigidity of the container gradually increases, which is beneficial for maintaining its shape during the seedling stage. However, when the lignin content approaches or exceeds the upper limit of 30 wt% (e.g., 40 wt% in Comparative Example 6), the brittleness of the container increases significantly, leading to a greater risk of breakage during handling. Simultaneously, due to the inherently recalcitrant nature of lignin, high lignin content significantly slows down the disintegration rate of the container in composting or soil environments, resulting in a decrease in both the degree of disintegration and the rate of biodegradation. Therefore, 0.1 wt%–30 wt% represents the optimal range for balancing mechanical strength and degradation performance.

[0235] The influence trend of inorganic filler addition: In PHA-based coatings, as the addition of inorganic fillers (such as talc, calcium carbonate, etc.) increases from 0.05 times to 0.55 times, the heat resistance and modulus of the coating improve, and the cost decreases. However, as the addition amount further increases and approaches or exceeds the upper limit of 0.55 times (such as 0.70 times in Comparative Example 7), the aggregation of inorganic particles in the polymer matrix intensifies, destroying the continuous and dense structure of the coating. This leads to a sharp increase in water vapor transmission rate (WVTR) and Cobb water absorption, and a significant decrease in wet tensile strength retention. This indicates that excessive inorganic fillers will sacrifice the barrier performance of the coating.

[0236] The effect of the amount of the second polymer added: As the amount of the second polymer (such as PBAT, PBS, etc.) increases from 0 to 0.60 times, the flexibility and adhesion of the PHA-based coating to the paper substrate generally tend to improve, which helps to reduce coating cracking. However, when the amount added exceeds the upper limit of 0.60 times (such as 0.80 times in Comparative Example 10), due to the compatibility limitations between different polymers, phase separation structures may occur, which will reduce the density and water resistance of the coating, resulting in a decrease in wet strength retention.

[0237] The influence trend of the directional failure zone area fraction: As the directional failure zone area fraction increased from 1% to 35%, the root penetration rate and container disintegration rate after transplanting showed a significant upward trend, exhibiting a positive correlation. However, when the area fraction exceeded 35% (e.g., 50% in Comparative Example 8), the overall wet structural stability of the container during the seedling stage decreased sharply, and the resistance to softening and collapse score showed a precipitous drop. This indicates that the failure zone area must be controlled within 35% to ensure safety during the seedling stage.

[0238] The effect of the amount of hydrophilic porosilicate added: In the directional failure zone, as the amount of hydrophilic porosilicate added (such as modified starch and inorganic salts) increased from 0.05 times to 0.40 times, the water absorption, softening, and pore-opening speed after contact with soil moisture accelerated, and the root penetration rate increased accordingly. However, when the amount added exceeded 0.40 times (such as 0.60 times in Comparative Example 11), the hygroscopic sensitivity of this zone was too high, and excessive water absorption began even under spraying conditions during the seedling stage, leading to a significant increase in the risk of sidewall leakage and mold growth.

[0239] The impact of stabilized coffee grounds content: In the seedling substrate module, as the stabilized coffee grounds content increased from 10 wt% to 40 wt%, the substrate's aeration and slow-release nutrient supply capacity improved, and the seedling survival rate and dry weight remained at a high plateau. When the content was <10 wt%, the nutrient contribution was not significant; however, when the content exceeded 40 wt% (e.g., 50 wt%), due to the substrate's excessive water retention and the potential risk of secondary fermentation, the probability of mold growth increased exponentially, leading to a significant decrease in seedling survival rate and biomass.

[0240] In summary, by controlling the key components and structural parameters within a specific range, this invention achieves global optimization of the seedling container's performance throughout its entire life cycle. This not only meets the seedling requirements of modern horticultural automation but also provides a scientifically feasible solution for the reduction and resource utilization of agricultural waste.

[0241] Those skilled in the art should understand that the above embodiments are merely exemplary and are not intended to limit the scope of the present invention. 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 protection scope of the present invention.

Claims

1. A compostable and biodegradable seedling paper-based system, characterized in that, The seedling paper-based system includes a seedling paper-based container, a drainage and ventilation structure, a polyhydroxy fatty acid ester-based biodegradable barrier coating, and a directional failure zone. The seedling paper-based container is selected from one or more of seedling cups, seedling pots, seedling trays, and seedling bags; The seedling paper-based container includes a paper fiber-based container body, which has side walls and a bottom and forms a cavity for accommodating the seedling substrate. The drainage and ventilation structure is provided in at least one area of ​​the bottom or side wall to form a drainage channel or ventilation channel during the seedling stage, and the drainage and ventilation structure is selected from one or more of drainage holes, ventilation holes, slits, grooves and guide channels. When the drainage and ventilation structure includes a drainage hole or a ventilation hole, the hole wall or edge area of ​​the drainage hole or ventilation hole is an uncoated area or a weakly coated area, and the orifice is not continuously sealed by the polyhydroxy fatty acid ester-based biodegradable barrier coating. The polyhydroxyalkanoate-based biodegradable barrier coating is disposed on the inner or outer surface of the paper fiber-based container body. The polyhydroxyalkanoate-based biodegradable barrier coating is formed by coating an aqueous coating composition containing polyhydroxyalkanoates and then drying it to provide water or moisture barrier retention during the seedling stage. The directional failure zone is disposed in at least one area of ​​the sidewall or bottom, and the directional failure zone is an uncoated area, a weakly coated area, or a coated area containing hydrophilic porous components; The aqueous coating composition comprises a second polymer and an inorganic filler.

2. The compostable and biodegradable seedling paper-based system according to claim 1, characterized in that: The uncoated area is the area not covered by the polyhydroxy fatty acid ester-based biodegradable barrier coating; The weakly coated area is the region where the ratio of the dry film coating amount per unit area of ​​the polyhydroxyalkanoate-based biodegradable barrier coating in this area to the dry film coating amount per unit area of ​​the adjacent coated area is >0 and ≤0.60, or the ratio of the average coating thickness of the polyhydroxyalkanoate-based biodegradable barrier coating in this area to the average coating thickness of the adjacent coated area is >0 and ≤0.

60. When the seedling paper-based container is transplanted or placed in soil or composting environment, the directional failure zone triggers the polyhydroxyalkanoate-based biodegradable barrier coating to become porous, cracked, or have reduced continuity, allowing water, microorganisms, and roots to enter or penetrate through the directional failure zone, thereby promoting the disintegration and biodegradation of the paper fiber-based container body.

3. The compostable and biodegradable seedling paper-based system according to claim 1, characterized in that: The paper fiber-based container body is a pulp molded part or a cardboard folded or rolled part; The paper fiber raw material is selected from one or more of wood pulp, bamboo pulp, sugarcane pulp, hemp pulp, rice and wheat straw pulp, reed pulp, sisal pulp, kenaf pulp, cotton linter pulp, and waste paper pulp, wherein the waste paper pulp is selected from one or more of newspaper-based recycled fiber pulp, corrugated cardboard box recycled fiber pulp, and office waste paper recycled fiber pulp; Furthermore, the paper fiber-based container body contains lignin or lignin derivatives, with an addition amount of 0.1 wt% to 30 wt% based on oven-dry fibers. The lignin derivatives are selected from one or more of alkali lignin, lignin sulfonate, oxidized lignin, esterified lignin, and etherified lignin.

4. The compostable and biodegradable seedling paper-based system according to claim 1, characterized in that: The polyhydroxy fatty acid ester is selected from short-chain polyhydroxy fatty acid esters, medium- and long-chain polyhydroxy fatty acid esters, or copolymer polyhydroxy fatty acid esters formed by monomers that form short-chain polyhydroxy fatty acid esters and medium- and long-chain polyhydroxy fatty acid esters. The short-chain polyhydroxy fatty acid ester is selected from one or more of poly3-hydroxybutyrate, poly3-hydroxybutyrate-co-4-hydroxybutyrate and poly3-hydroxybutyrate-co-3-hydroxyvalerate; The medium- and long-chain polyhydroxy fatty acid esters are selected from one or more of poly(3-hydroxyhexanoate), poly(3-hydroxyheptanoate), poly(3-hydroxyoctanoate), poly(3-hydroxynonanoate), poly(3-hydroxydecanoate), poly(3-hydroxyundecanoate), poly(3-hydroxydodecanoate), poly(3-hydroxytetrate), poly(3-hydroxytetradecanoate), poly(3-hydroxytetradecanoate), poly(3-hydroxypentadecanoate), poly(3-hydroxyhexadecanoate), poly(3-hydroxyhexadecanoate), poly(3-hydroxyheptadecanoate), and poly(3-hydroxyheptadecanoate). The second polymer is an aliphatic polyester or an aliphatic-aromatic copolyester; the aliphatic polyester or aliphatic-aromatic copolyester is formed by polycondensation or ring-opening polymerization of one or more of the following monomers: lactic acid, lactide, glycolic acid, glycolide, ε-caprolactone, succinic acid, adipic acid, sebacic acid, terephthalic acid, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol and diethylene glycol; Furthermore, the dry basis of the second polymer is added at a rate of 0 to 0.60 times the dry basis mass of the polyhydroxy fatty acid ester in the aqueous coating composition.

5. The compostable and biodegradable seedling paper-based system according to claim 1, characterized in that: The inorganic filler is selected from one or more of talc, kaolin, silica, calcium carbonate, mica, bentonite, diatomaceous earth, titanium dioxide, zinc oxide, and magnesium hydroxide; and the dry basis amount of the inorganic filler is 0.05 to 0.55 times the dry basis mass of the polyhydroxyalkanoate in the aqueous coating composition.

6. The compostable and biodegradable seedling paper-based system according to claim 1, characterized in that: The polyhydroxy fatty acid ester-based biodegradable barrier coating has a single-layer or multi-layer structure. When it is a multilayer structure, it includes a paper-friendly base coating and a polyhydroxyalkanoate barrier coating, wherein the paper-friendly base coating contains a water-soluble polysaccharide or a cellulose derivative, wherein the water-soluble polysaccharide is selected from one or more of modified starch, dextrin and maltodextrin, and the cellulose derivative is selected from one or more of sodium carboxymethyl cellulose, hydroxyethyl cellulose and hydroxypropyl methyl cellulose; Furthermore, the total dry film thickness of the polyhydroxyalkanoate-based biodegradable barrier coating on one side is 8 μm to 55 μm.

7. The compostable and biodegradable seedling paper-based system according to claim 1, characterized in that: The directional failure region is selected from one or more of the following: strip-shaped, lattice-shaped, grid-shaped, ring-shaped, spiral-shaped, microporous region, open-pore region, and slotted region; The directional failure zone accounts for 1% to 35% of the total area of ​​the inner or outer surface actually coated on the paper fiber-based container body; When the polyhydroxyalkanoate-based biodegradable barrier coating in the directional failure region contains a hydrophilic porous component, the hydrophilic porous component is selected from one or more of water-soluble polysaccharides, cellulose derivatives, water-soluble polyethers, water-soluble lactam polymers, and water-soluble inorganic salts. The water-soluble polysaccharides are selected from one or more of modified starch, dextrin, and maltodextrin. The cellulose derivatives are selected from one or more of sodium carboxymethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose. The water-soluble polyethers include polyethylene glycol. The water-soluble lactam polymers include polyvinylpyrrolidone. The water-soluble inorganic salts are selected from one or more of sodium chloride, potassium chloride, potassium sulfate, and sodium bicarbonate. Furthermore, the dry basis addition amount of the hydrophilic porous component is 0.05 to 0.40 times the dry basis mass of the polyhydroxy fatty acid ester-based biodegradable barrier coating in the directional failure region.

8. The compostable and biodegradable seedling paper-based system according to claim 1, characterized in that: The periphery of the drainage hole or vent hole constitutes at least a portion of the directional failure zone to reduce the risk of the orifice being blocked by the coating and causing water accumulation.

9. The compostable and biodegradable seedling paper-based system according to claim 1, characterized in that, The seedling paper-based system includes a seedling support module, which is selected from one or more of a seed module, a seedling substrate module, and a tray module. The seedling substrate module contains an organic substrate component, which is selected from one or more of compressed coconut coir, peat, pulp substrate, compost substrate, and bark humus. Furthermore, the seedling substrate module contains stabilized coffee grounds, which are obtained through aerobic composting and sieving; the mass fraction of the stabilized coffee grounds is 10wt% to 40wt% based on the dry basis of the seedling substrate; the seedling substrate module contains a pH buffer component, which is selected from one or more of dolomite powder, calcium carbonate, and wood ash; the seedling substrate module contains a substrate conditioning component, which is selected from one or more of perlite, vermiculite, zeolite, and pumice.

10. The compostable and biodegradable seedling paper-based system according to claim 1, characterized in that: The seedling paper-based container and its polyhydroxyalkanoate-based biodegradable barrier coating, under controlled composting conditions at 58±2℃, exhibit an ultimate aerobic biodegradation rate of ≥90% after 180 days, as measured by GB / T 19277.1-2025, and a degree of disintegration of ≥90% after 84 days of composting, as measured by ISO 20200:2023. Furthermore, the compost product of the seedling paper-based container and its polyhydroxyalkanoate-based biodegradable barrier coating was mixed with standard test soil at a dry basis mass fraction of 5 wt% as the treatment group, and the standard test soil without compost product was used as the blank control. Plant emergence and early growth experiments were conducted in accordance with ISO 11269-2:2012. The plant emergence rate and plant biomass of the treatment group were both ≥90% of the corresponding values ​​of the blank control.

11. The compostable and biodegradable seedling paper-based system according to claim 1, characterized in that: The total organic fluorine content of the seedling paper-based container and its polyhydroxyalkanoate-based biodegradable barrier coating, as measured according to EN 14582:2016, is <5 mg / kg, which is the detection limit.

12. A method for preparing a compostable and biodegradable seedling paper-based system according to claim 1, characterized in that: The preparation method includes the following steps: Step 1. Preparation of paper fiber-based container body: The paper fiber-based container body is prepared by pulp molding process or paperboard folding and rolling process; Step 2. Preparation of the coated container body: Aqueous dispersion of polyhydroxyalkanoate, inorganic filler, or aqueous dispersion of polyhydroxyalkanoate, inorganic filler and a second polymer aqueous dispersion are mixed and dispersed to obtain an aqueous coating composition; the aqueous coating composition is coated on the inner or outer surface of the paper fiber-based container body and dried to form a film to obtain a coated container body with a polyhydroxyalkanoate-based biodegradable barrier coating; Step 3. Forming a directional failure zone: The predetermined area of ​​the coated container body obtained in Step 2 is masked or locally thinned, or a hydrophilic porous component is introduced into the predetermined area to obtain a coated container body with a directional failure zone; Step 4. Forming a drainage and ventilation structure: A drainage and ventilation structure is formed on the coated container body with directional failure zone obtained in Step 3 to obtain a seedling paper-based container; Step 5. Assembly: Assemble the seedling paper-based container obtained in Step 4 with the seedling substrate module, seed module and tray module into a set or complete the packaging to obtain the seedling paper-based system.

13. The preparation method according to claim 12, characterized in that: In step 1 of the preparation method, when using a pulp molding process, paper fiber raw materials are dispersed with water to form a paper fiber pulp. The paper fiber pulp is pumped to a molding die and dehydrated under vacuum before demolding to obtain a wet container body blank. The wet container body blank is further dehydrated and dried, and then structurally shaped by hot pressing or densification. When using a cardboard folding and rolling process, cardboard is selected, and after die-cutting to obtain an unfolded sheet, it is crimped and folded or rolled into shape. Water-based starch adhesive is used as an overlap bonding agent, and then the shape is completed under hot pressing conditions. In step 2, before coating the aqueous coating composition, a paper-friendly undercoating composition comprising water-soluble polysaccharides or cellulose derivatives is coated on the inner or outer surface of the paper fiber-based container body obtained in step 1 and dried to form a paper-friendly undercoating; subsequently, the aqueous coating composition is coated on the paper fiber-based container body or the paper-friendly undercoating. In step 3, the predetermined area includes a periphery ring area of ​​the drain hole or vent hole, and the width of the ring area is 1.0 mm; In step 4, the drainage and ventilation structure is formed by any of the following methods: punching, laser drilling or needle punching the coated container body to form drainage holes or ventilation holes; or forming a slit at the bottom of the container and pressing a guide groove on the outer surface of the bottom.

14. A method for seedling cultivation and easy composting disposal using the compostable and biodegradable seedling paper-based system according to claim 1, characterized in that: The method includes placing seed or seedling substrate and seeds or seedlings in a seedling paper-based container for seedling management; After the seedlings are cultivated, the seedling paper-based container, along with the substrate and the plant, is transplanted into a soil environment, a home composting environment, or an industrial composting environment. This allows water, microorganisms, and roots to enter or penetrate through the directional failure zone, and promotes the porosity, cracking, or discontinuity reduction of the polyhydroxyalkanoate biodegradation barrier coating. At the same time, it causes the paper fiber-based container to gradually disintegrate and biodegrade, thereby achieving overall easy composting disposal.

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