Transformable seedling cup for paper cup and coffee residue cooperative utilization and preparation method thereof

Abstract

The application discloses a paper cup and coffee residue synergic utilization convertible seedling cup and a preparation method thereof, and belongs to the field of solid waste resource utilization. In view of the pain point of traditional paper cup recycling, the application innovatively constructs a whole life cycle function conversion mechanism of "drinks containing-transplanting ventilation-planting degradation". Through the synergy of a special double-effect barrier coating and an external force activation structure, perfect balance between drinks-level barrier and intelligent root guidance during the seedling period can be achieved with only a very low coating amount, which significantly improves resource utilization and reduces material consumption compared with traditional single-function solutions. In combination with a standardized coffee residue substrate, in-situ closed-loop utilization of store solid waste is realized. The scheme provides an efficient carbon reduction solution with ecological benefits and commercial value for the industry.

Description

Technical Field

[0001] This invention belongs to the field of solid waste resource utilization, specifically involving a convertible seedling cup that utilizes paper cups and coffee grounds in combination, and its preparation method. Background Technology

[0002] The consumption of disposable paper-based beverage cups in coffee shops and chain beverage establishments is substantial, and the coffee extraction process generates a large amount of coffee grounds; both are typical examples of solid waste from household sources. Traditional disposal methods often result in these cups ending up in mixed waste systems, leading to the loss of fiber and organic resource value and increasing the pressure on end-of-life disposal.

[0003] Several publicly disclosed solutions exist regarding the reuse of paper-based cups and biodegradable seedling containers. For example, CN201436841U discloses a paper planting container with an organically biodegradable waterproof membrane covering the inner side and perforations at the bottom that can be punctured. When the perforations are intact, they can hold liquid; when punctured, they form drainage holes, allowing for planting and subsequent decomposition after transplanting into the soil along with the container. CN205902492U discloses a biodegradable seedling paper cup with a polylactic acid (PLA) fiber paper base layer coated with a nutrient layer. After seedling cultivation, the cup can be transplanted and degraded. CN103314766A and its authorized text disclose a method for direct seeding cultivation of seeds in a cup-filled substrate and a paper cup direct seeding carrier, using biodegradable paper cups with perforated walls as direct seeding carriers for seedling cultivation or direct seeding.

[0004] In the area of ​​coffee grounds resource utilization and seedling media, existing publicly available solutions, such as CN103348881A and its authorized text, disclose nutrient pots for coffee grounds seedling substrates. These pots utilize staged fermentation or composting, introducing composting bacteria, functional bacteria, sugars, binders, and water-retaining agents to degrade alkaloids, phenols, and oils in the coffee grounds, thus creating nutrient pots. Other publicly available solutions utilize processed coffee processing residues or coffee grounds as seedling substrates or cultivation substrate systems. Public literature reports that uncomposted coffee grounds contain caffeine, tannins, and chlorogenic acid, which may inhibit bud growth and development. These factors typically require composting, dilution, or stabilization to mitigate these adverse effects. Unlike the aforementioned "fermentation and composting followed by pot making" approach, this application focuses on stabilization treatment, including dehydration, hot water extraction, sterilization, or maturation. The stabilized coffee grounds are then compounded with the seedling substrate to create standardized, fillable substrate components, adapting to the transition between beverage-use (paper cups) and seedling-use (soup) conditions.

[0005] In the field of paper-based barrier coatings, US20180171559A1 discloses a method for improving barrier performance by setting a compostable polymer coating on a cellulose substrate; US9670621B2 discloses a coating composed of binders and pigments to obtain paperboard that is oil-resistant, grease-resistant, and moisture-resistant, while also being repulpable and compostable. Dubaicheng New Materials Technology (Shanghai) Co., Ltd. and Zhongke Lianhua Co., Ltd., among others, have disclosed several solutions related to waterborne polyhydroxyalkanoate (PHA) barrier coatings. For example, WO2020036843A1 discloses a biodegradable coating system based on waterborne PHA dispersions; CN120925357A discloses a repulpable and biodegradable PHA heat-sealing barrier coating; and CN120759147B discloses a bio-based PHA oil-blocking and moisture-permeable coating for hamburger paper, which improves barrier performance and flexibility through a functional gradient structure. FR3071190B1 and others disclose a manufacturing method of applying a biodegradable varnish or coating to the inside of a paper cup and then heat-sealing it into a cup; CN119593245A, CN116411484A and others disclose different types of bio-based or water-based barrier coatings or plastic-free coated paper for use in paper cups or food packaging.

[0006] Other solutions, such as WO2009156855A2, disclose methods for embedding seeds or matching seed labels into disposable biodegradable cups or utensils to guide planting after use. The aforementioned coating and planting guidance solutions mainly target single objectives such as food packaging barrier, heat sealing, re-sizing, or planting guidance. They do not address the synergistic effects of cleaning and drying processes for beverage reuse, activating drainage and aeration structures, and restoring root extension pathways in directional failure zones within a preset time window in soil or compost environments. Nor do they couple coffee oil obtained from hot water extraction of coffee grounds as a source of hydrophobic conditioning components for coatings and coffee grounds composite matrix components into the same recycling chain.

[0007] However, existing technologies still generally suffer from the following shortcomings: First, most solutions position paper cups or paper containers for a single purpose, namely only for beverages or only for seedling cultivation and planting. Even those that combine the idea of ​​holding liquids and planting usually lack a sequential functional design of "high barrier during the beverage stage - drainage and aeration during the seedling stage - directional failure recovery and permeability after transplanting". In particular, they lack the structure-coating synergy of constructing an aeration and root-guiding area and a controllable failure window at the bottom or side wall of the cup. Second, existing paper-based barrier coatings mainly focus on packaging indicators such as water and oil resistance, heat sealing, re-pulping or compostability, and lack the construction of root penetration and gas exchange pathways for transplanting in cups. Third, coffee grounds seedling media are mostly produced by fermentation and composting to make nutrient pots or substrates, but lack standardized assembly methods with paper-based beverage cups, as well as modular substrate components adapted to the beverage-seedling conversion process. Therefore, a convertible seedling cup with synergistic material-structure-time-sequence function is needed. This cup should reliably prevent leakage during the beverage stage, allow controlled drainage and aeration during the seedling stage, and restore permeability within a predetermined window after transplanting, promoting cup disintegration and root extension, thereby reducing the transplanting process. Furthermore, coffee grounds should be introduced into the seedling system in a standardized substrate manner. Even combining existing perforated paper planting containers, water-based PHA barrier coatings for food packaging, and coffee grounds fermentation and composting nutrient pots still fails to achieve a synergistic design that simultaneously satisfies continuous barrier during the beverage stage, activates drainage and aeration during the seedling stage, and restores permeability in the directional failure zone within a predetermined time window after transplanting, forming root extension pathways. There is also a lack of technical inspiration to introduce coffee oil obtained from hot water extraction of coffee grounds into the barrier coating system to achieve a closed-loop recycling chain.

[0008] In summary, the industry urgently needs to develop a paper-based container and its preparation technology that can simultaneously ensure the safety of beverage packaging and facilitate seedling cultivation. This technology needs to break free from the limitations of single-use applications and, through deep synergy between material modification and structural design, construct a full life-cycle functional evolution mechanism: continuous barrier during the beverage stage – controlled aeration during the seedling stage – directional failure during the transplanting stage. Specifically, it needs to address the technical bottlenecks of poor drainage at the bottom of the cup, difficulty in guiding roots through the side walls, and slow degradation in soil, all while ensuring a pleasant beverage experience. Simultaneously, there is an urgent need to develop a closed-loop pathway for the in-situ resource utilization of coffee grounds and coffee oil generated in coffee shops, transforming them into standardized seedling substrate components and environmentally friendly coating components. This would achieve zero-waste conversion and high-value regeneration of coffee consumption solid waste, promoting the green integration and development of the packaging and horticulture industries. Summary of the Invention

[0009] The purpose of this invention is to overcome the shortcomings of the prior art and provide a convertible seedling cup that utilizes paper cups and coffee grounds in combination, as well as its preparation method.

[0010] To achieve the above objectives, the present invention provides the following technical solution:

[0011] This invention provides a convertible seedling cup that utilizes both paper cups and coffee grounds, comprising: a paper-based cup body having a bottom and sidewalls forming a receiving cavity; a barrier coating suitable for composting disposed on the inner surface of the paper-based cup body, the barrier coating comprising a film-forming adhesive phase and a mineral-based barrier phase, and the barrier coating forming a continuous closed barrier area and a directional failure area on the same paper-based cup body, the continuous closed barrier area being used to continuously block liquid water or oil in the beverage usage state; an externally activated drainage and ventilation structure disposed on the bottom and / or sidewalls of the cup, the externally activated drainage and ventilation structure comprising a preset weakening area and a sealing part, the externally activated drainage and ventilation structure being in an inactive state in the beverage usage state, preventing the receiving cavity from communicating with the outside, and the sealing part and the barrier coating jointly forming a continuous barrier; and at least three drainage holes and at least one ventilation channel communicating with the drainage holes, formed by external activation in the seedling usage state.

[0012] The directional failure zone is located in the area corresponding to the externally activated drainage and aeration structure and / or in the aeration and root-guiding area on the sidewall. This ensures the barrier coating maintains continuous barrier function during beverage use, while maintaining gas exchange at least in the directional failure zone during seedling use. Within a preset time window of 7–180 days after transplanting in a soil environment or controlled compost environment, the directional failure zone undergoes porosity, cracking, or a transformation from a continuous membrane to a discontinuous membrane. This allows the paper-based cup to become permeable to water in the directional failure zone, forming an extensional pathway for the roots. The preset time window of 7–180 days can specifically include 7 days, 10 days, 14 days, 20 days, 30 days, 45 days, 60 days, 90 days, 120 days, 150 days, and 180 days. It should be noted that "suitable for composting" as described in this article means that the material can disintegrate and biodecompose in a controlled composting environment, and at least meets the following quantifiable conditions: the aerobic biodegradation rate after 180 days is ≥90% as measured by GB / T 19277.1-2025 under controlled composting conditions at 58℃, and the degree of disintegration after 12 weeks is ≥90% as measured by ISO 20200:2023.

[0013] The coffee grounds composite matrix component placed in the containment cavity during seedling use comprises a compound of stabilized coffee grounds and seedling matrix; wherein, the beverage use state is the use state of holding a beverage in a paper-based cup, and the seedling use state is the use state of filling a paper-based cup with the coffee grounds composite matrix component and watering the seedlings.

[0014] The film-forming binder phase is selected from one or more of the following: PHA, wherein the PHA is selected from short-chain PHA, medium- and long-chain PHA, or copolymers between monomers forming short-chain and medium- and long-chain PHA; wherein the short-chain PHA is selected from one or more of poly(3-hydroxybutyrate) (PHB), poly(3-hydroxybutyrate-co-4-hydroxybutyrate) (P34HB), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV); the medium- and long-chain PHA is selected from poly(3-hydroxyhexanoate) (PHH), poly(3-hydroxyoctanoate) (PHO), poly(3-hydroxydecanoate), poly(3-hydroxydodecanate), poly(3-hydroxydodecanate), poly(3-hydroxytetradecanoate), and poly(3-hydroxytetradecanoate). One or more of (3-hydroxyhexadecanoate), poly(3-hydroxyoctadecanoate) and its copolymers; polymers polymerized or copolymerized from one or more of the following monomers and suitable for composting: lactic acid, glycolic acid, ε-caprolactone, succinic acid, adipic acid, sebacic acid, terephthalic acid, isophthalic acid, 1,2-ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, vinyl acetate; bio-based film-forming binders formed from starch and its derivatives, cellulose and its derivatives, chitosan, alginate, pectin, protein, lignin and its derivatives; water-dispersible inorganic binders of silica sol, alumina sol, zirconium sol, titanium sol, silicate hydrosol and water glass modified systems.

[0015] The mineral-based barrier phase is selected from lamellar silicate mineral fillers, layered clay mineral fillers, acicular or fibrous silicate mineral fillers, carbonate mineral fillers, siliceous porous mineral fillers, hydroxide barrier fillers, or combinations thereof; wherein, lamellar silicate mineral fillers include kaolin, mica, and talc; layered clay mineral fillers include montmorillonite, bentonite, halloysite, and vermiculite; acicular or fibrous silicate mineral fillers include wollastonite, attapulgite, and sepiolite; carbonate mineral fillers include calcium carbonate and magnesium carbonate; and siliceous porous mineral fillers include... Diatomaceous earth and silicon dioxide; the hydroxide barrier filler includes aluminum hydroxide and magnesium hydroxide; based on the dry solids of the barrier coating, the mass fraction of the mineral-based barrier phase is 20wt% to 95wt%, specifically including 20wt%, 25wt%, 30wt%, 35wt%, 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, 80wt%, 84.2wt%, 85wt%, 90wt%, 95wt%, etc.

[0016] The directional failure zone is formed through one or more of the following methods: the coating amount or film thickness of the directional failure zone is reduced relative to the adjacent area; the directional failure zone is a discontinuous film area formed by intermittent coating, avoidance coating, or grid-like coating; the directional failure zone contains a porosity failure regulating component, which is selected from water-soluble sugars, water-soluble oligosaccharides, water-soluble polysaccharides, sugar alcohols, polyols, water-soluble polymers, or combinations thereof, wherein the water-soluble polymer is selected from one or more of polyvinyl alcohol (PVA), polyethylene glycol (PEG), and polyvinylpyrrolidone (PVP); the directional failure zone is provided with fracture guide lines, microcracks, or micropore arrays; and the barrier coating is a gas-liquid selective barrier coating: in the beverage use state, it forms a continuous barrier to liquid water or oil, and in the seedling use state, it is permeable to gas at least in the directional failure zone to maintain gas exchange.

[0017] The externally activated drainage and ventilation structure includes a preset weakened area and a sealing part: in the beverage usage state, the sealing part covers the preset weakened area and together with the barrier coating forms a continuous closed barrier area; in the seedling usage state, pressing or folding opens the preset weakened area, forming at least three drainage holes connecting the receiving cavity to the outside and at least one ventilation channel communicating with the drainage holes. The preset weakened area is preferably designed as a cross-shaped indentation and combined with four radial cuts to form a weakened pattern, ensuring stress concentration and fracture guidance under external force; after activation, the cross-shaped indentation guides the bottom of the cup to form a flipped petal structure, and the petals and the ventilation gap formed by the support feet or annular flange on the outside of the bottom of the cup together form a radial ventilation channel, allowing outside air to enter the drainage holes through the ventilation channel and communicate with the receiving cavity, thereby maintaining bottom ventilation and drainage stability when the supporting surface is present.

[0018] The sealing portion is a sealing sheet, sealing film, or sealing coating made of composting materials, such as a PHA film or a cellulose film, and is attached to the outer or inner surface of a pre-defined weakened area by an aqueous adhesive.

[0019] The externally activated drainage and ventilation structure forms at least three drainage holes after activation. The diameter of the drainage holes is 2-8 mm, specifically including 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, 6 mm, 7 mm, 8 mm, etc. Under the conditions of a 10 mm diameter cylindrical pressure head and a loading rate of 50 mm / min, the activation peak force of the externally activated drainage and ventilation structure when forming drainage holes is 12-20 N, specifically including 12 N, 13 N, 14 N, 15 N, 16 N, 17 N, 18 N, 19 N, 20 N, etc.

[0020] The ventilation guide root region of the sidewall is at least one strip-shaped region extending along the axial direction of the cup body. The width of the strip-shaped region is 5-30 mm, specifically including 5 mm, 8 mm, 10 mm, 12 mm, 15 mm, 18 mm, 20 mm, 25 mm, 30 mm, etc.; the length of the strip-shaped region accounts for 30%-90% of the height of the sidewall, specifically including 30%, 35%, 40%, 45%, 50%, 60%, 70%, 80%, 90%, etc.; and the area of ​​the strip-shaped region accounts for the sidewall height. The inner surface area of ​​the wall is 2% to 20%, specifically including 2%, 3%, 4%, 5%, 6%, 8%, 10%, 12%, 15%, 18%, 20%, etc.; the bottom of the cup is provided with a folded support foot or annular flange, so that the bottom of the cup and the supporting surface form a ventilation gap of 1 to 5 mm, specifically including 1 mm, 1.5 mm, 2 mm, 2.5 mm, 3 mm, 3.5 mm, 4 mm, 4.5 mm, 5 mm, etc.; the side wall of the paper-based cup body is rolled or the side seam is formed by water-based adhesive or ultrasonic welding.

[0021] The coffee grounds composite matrix component is a standard component of granules, plungers, compressed blocks, or seedling capsules; the stabilized coffee grounds are dehydrated and dried to a moisture content ≤10wt%, and then subjected to at least one of the following treatments: hot water extraction, low-temperature stacking maturation, steam sterilization, or hot air sterilization to reduce the risk of mold growth and weaken bud-inhibiting components. After the hot water extraction and the at least one treatment, the coffee grounds are dehydrated and dried again to a moisture content ≤10wt%; the hot water extraction process involves a dry-basis mass ratio of hot water to coffee grounds of 3–10:1, specifically including 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc.; the extraction temperature is 60–95℃, specifically including 60℃, 65℃, 70℃, etc. Temperatures include ℃, 75℃, 80℃, 85℃, 90℃, and 95℃; extraction time is 10–30 min, specifically including 10 min, 15 min, 20 min, 25 min, and 30 min; extraction times are 1–3 times, specifically including 1 time, 2 times, and 3 times; the stabilized coffee grounds account for 5 wt%–70 wt% of the mass fraction of the coffee grounds composite matrix component on a dry basis, specifically including 5 wt%, 10 wt%, 15 wt%, 20 wt%, 25 wt%, 30 wt%, 35 wt%, 40 wt%, 45 wt%, 50 wt%, 55 wt%, 60 wt%, 65 wt%, 68.7 wt%, and 70 wt%.

[0022] The coffee grounds composite matrix component includes a pH buffer component to maintain the pH of the compound at 5.5–7.5, specifically including 5.5, 5.8, 6.0, 6.2, 6.4, 6.5, 6.6, 6.8, 7.0, 7.2, and 7.5; the pH buffer component is selected from dolomite powder, calcium carbonate, magnesium carbonate, calcium hydroxide, or combinations thereof; the coffee grounds composite matrix component further includes a conductivity regulating component to maintain the electrical conductivity according to the International Organization for Standardization (ISO) standard. The current version of 11265 measures the conductivity of the matrix extract to be 0.1–0.2 mS / cm, specifically including 0.10 mS / cm, 0.12 mS / cm, 0.14 mS / cm, 0.15 mS / cm, 0.16 mS / cm, 0.17 mS / cm, 0.18 mS / cm, 0.19 mS / cm, 0.20 mS / cm, etc.; the conductivity regulating component is selected from zeolite powder, biochar, perlite, vermiculite, or combinations thereof; and the coffee grounds composite matrix component further includes slow-release fertilizer; the seedling substrate is selected from coconut coir, peat moss, humus, compost, wood fiber, rice husk charcoal, perlite, vermiculite, or combinations thereof; the coffee grounds composite matrix component is provided with sowing recesses or pre-placed seeds.

[0023] This invention also provides a barrier coating composition suitable for home composting or controlled composting of the inner surface of the paper-based cup used in the above-mentioned coffee paper cup conversion seedling cup, comprising: a film-forming binder phase selected from one or more of film-forming polymers, bio-based film-forming binders, and water-dispersible inorganic binders suitable for home composting or controlled composting; a mineral-based barrier phase, which is a sheet-like, layered, needle-like, or porous inorganic mineral filler; a medium that is water, an alcohol-water mixture, or a water-polyol mixture, wherein the polyol is selected from glycerol, propylene glycol, 1,3-propanediol, sorbitol, or combinations thereof; and additives including dispersants, thickeners, defoamers, wetting agents, rheology modifiers, hydrophobic conditioning components, or pore failure control components. The barrier coating composition of the present invention is an aqueous system with good processing adaptability. It can be applied using existing paper cup manufacturing equipment such as internal coating, roller coating, spraying or scraping. It also has good compatibility with water-based adhesives or ultrasonic welding processes commonly used in the paper cup forming process, ensuring the feasibility of industrial production.

[0024] The composition, after being coated and dried to form a film, forms a continuous water-blocking or oil-blocking film layer in the beverage usage state; and the composition is used to form a coating in two regions on the same paper-based cup body: a continuous closed barrier region and a directional failure region. The directional failure region is formed by patterned coating, local thinning, intermittent coating, or the introduction of a porosity failure regulating component. The dry basis mass fraction of the porosity failure regulating component in the directional failure region is higher than that in the continuous closed barrier region, or the porosity failure regulating component exists only in the directional failure region, so that it porosifies, cracks, or transforms from a continuous membrane to a discontinuous membrane in the directional failure region in a seedling environment, soil environment, home composting environment, or controlled composting environment to restore permeability.

[0025] The hydrophobic conditioning component is coffee oil or coffee oil emulsion; the composition further includes a plasticizer selected from citrate esters, lactate esters or combinations thereof, and preferably added at an amount of 1wt% to 10wt% of the dry basis mass of the film-forming binder to improve the flexibility of the coating film, specifically including 1wt%, 2wt%, 3wt%, 4wt%, 5wt%, 6wt%, 7wt%, 8wt%, 9wt%, 10wt%, etc.

[0026] The composition further comprises a crosslinking agent selected from citric acid, tartaric acid, malic acid, or combinations thereof. To improve wet durability, the preferred amount of the crosslinking agent is 0.2wt% to 5wt% of the dry basis mass of the film-forming binder, specifically including 0.2wt%, 0.5wt%, 1.0wt%, 1.5wt%, 2.0wt%, 2.5wt%, 3.0wt%, 3.5wt%, 4.0wt%, 4.5wt%, 5.0wt%, etc.

[0027] The composition further comprises a natural antibacterial component selected from chitosan, tea polyphenols, or combinations thereof. To reduce the risk of mold growth in the substrate or cup during the subsequent seedling stage, the preferred addition amount is 0.1wt% to 2wt% of the dry basis weight of the barrier coating, specifically including 0.1wt%, 0.2wt%, 0.5wt%, 0.8wt%, 1.0wt%, 1.2wt%, 1.5wt%, 1.8wt%, 2.0wt%, etc.

[0028] After the coating sample of the composition was coated and dried into a film, it was subjected to water extraction to remove soluble inorganic fluorine. The organic fluorine content was determined to be less than 5 mg / kg according to the oxygen bomb combustion-ion chromatography method in accordance with European standard EN 14582:2016.

[0029] The present invention also provides a method for preparing the above-mentioned coffee paper cup conversion seedling cup, comprising the following steps:

[0030] Step 1. Provide a paper-based cup blank to obtain a paper-based cup blank.

[0031] Step 2. Obtain coffee grounds produced during the coffee extraction or brewing process.

[0032] Step 3. Dehydrate and dry the coffee grounds obtained in Step 2, then perform hot water extraction and at least one of the following treatments: low-temperature stacking for maturation, steam sterilization, or hot air sterilization; subsequently, dehydrate and dry the solid phase of the extracted coffee grounds again to ensure that the moisture content of the stabilized coffee grounds is ≤10wt%, thus obtaining stabilized coffee grounds; combine the stabilized coffee grounds with seedling substrate and pH buffer components to form a coffee grounds composite substrate component; collect the hot water extraction liquid and centrifuge or allow it to stand and separate to recover coffee oil, thus obtaining the coffee grounds composite substrate component and coffee oil.

[0033] Step 4. Mix and disperse the film-forming binder phase, mineral-based barrier phase, medium, and additives to obtain a barrier coating composition. Apply the barrier coating composition to at least the inner surface of the paper-based cup blank obtained in Step 1 and dry it to form a barrier coating suitable for home composting or controlled composting. Simultaneously, directional failure zones are formed in predetermined areas through patterned coating, local thinning, intermittent coating, or the introduction of pore failure control components. To accurately form continuous closed barrier zones and directional failure zones on the same paper-based cup, a two-step patterned coating process is preferred: First, the continuous closed barrier zone barrier coating formulation is applied to the entire inner surface of the paper-based cup and dried under hot air conditions of 50℃~80℃ to form a basic barrier layer; then, the directional failure zone barrier coating formulation is locally applied to the inner surface annular area and / or the side wall ventilated root guide strip area corresponding to the preset weakened area at the bottom of the cup using a masking template and dried to form a film, thereby obtaining two-zone coatings on the same cup.

[0034] An externally activated drainage and ventilation structure is formed on the bottom or side wall of the cup, and a sealing part is provided. A preset weakened area is formed by indentation, cutting, or punching, and the sealing part is attached to the inner or outer surface of the preset weakened area so that the sealing part and the barrier coating form a continuous seal when the beverage is in use, resulting in a coffee paper cup. In step 4, the directional failure area is formed by reducing the local coating amount, intermittent coating, avoiding coating, adding porosity failure control components, or setting fracture guide lines. By adjusting the areal density, crosslinking degree, mineral-based barrier phase ratio, or porosity failure control component ratio of the barrier coating, the barrier coating will undergo porosity, cracking, or reduced continuity in the directional failure area within a preset time window after planting in the soil environment, home compost environment, or controlled compost environment, so as to promote the cup body permeability recovery and structural disintegration. The coffee oil obtained in step 3 is emulsified by high shear to obtain a coffee oil emulsion, and the coffee oil emulsion is added when preparing the barrier coating composition.

[0035] Step 5. After the beverage is used, remove the residual liquid from the coffee paper cup obtained in Step 4, rinse the inner surface with hot water at 60℃~90℃ and drain; then dry it under hot air at 50℃~80℃ for 5min~30min, so that there is no free liquid on the inner surface of the cup and the water content of the cup wall is ≤10wt%; the preferred standardized cleaning and drying process is as follows: after pouring out the residual liquid, add about 200mL of 80℃ hot water into the cup and rotate the cup to rinse the inner surface for 30s; invert the cup to drain for 2min; then place it under hot air at 70℃ to dry for 15min. After drying, the moisture content of the cup wall needs to be confirmed. When the moisture content of the cup wall is greater than 10wt%, continue to dry with 70℃ hot air every 5 minutes until the moisture content of the cup wall is ≤10wt% to ensure hygiene and drainage and aeration stability in the subsequent seedling stage. The moisture content of the cup wall is determined by drying at 105℃ to constant weight method. The moisture content is equal to the wet sample mass minus the dry sample mass, divided by the wet sample mass, and then multiplied by 100%. Activate the external force activated drainage and aeration structure to form drainage holes and aeration channels. Put the coffee grounds composite matrix component obtained in step 3 into the receiving cavity of the paper base cup to obtain the coffee paper cup conversion seedling cup.

[0036] Compared with the prior art, the following significant advantages can be obtained by using the present invention:

[0037] Full life cycle functional synergy: This invention innovatively constructs a cup system with full-link functional transformation from "beverage-seedling-planting". Through the temporal synergy of coating formulation and structural design, it achieves high water and oil resistance (Kit level ≥10, fluoride-free and safe) in the beverage stage, reliable drainage and aeration are achieved through external force activation in the seedling stage (activation force 12-20N, residual water volume ≤10mL after drainage), and in the planting stage, through the pore formation and cracking of the directional failure zone (preset window period 7-180 days), it breaks through the functional barriers of traditional paper cups being "disposable after use" and seedling pots being "unable to hold beverages".

[0038] Targeted root guidance and degradation mechanism: This invention effectively solves the root binding problem in cup transplanting by setting specific aeration and root guidance areas on the sidewalls and combining them with a directional failure coating. Experiments have shown that this design allows the roots to quickly penetrate the cup wall after transplanting (penetration rate ≥88% after 180 days). At the same time, the mineral-based filler promotes the disintegration of the polymer matrix, realizing the natural disintegration of the cup in the soil environment and avoiding damage to the seedling roots during transplanting.

[0039] Closed-loop utilization of solid waste resources: This invention transforms waste coffee grounds generated by coffee shops into standardized seedling substrate components through stabilization treatment, and converts recovered coffee oil into hydrophobic conditioning components for coatings, realizing the in-situ high-value utilization of coffee consumption solid waste. The compounded substrate has suitable pH and conductivity, significantly reducing the risk of mold growth (0% mold growth rate) and improving the germination rate, thus constructing a green and circular business model.

[0040] Safe, environmentally friendly, and eco-friendly: The barrier coating composition of this invention is completely free of organic fluorine and meets stringent food safety contact standards (migration levels are far below the limits). Furthermore, all materials meet the requirements for home composting or controlled composting (180-day biodegradation rate ≥90%), ensuring that the product will not cause microplastic or persistent chemical pollution to the soil and environment at the end of its entire life cycle under controlled composting and soil simulation testing conditions. Attached Figure Description

[0041] Figure 1 This is a cross-sectional structural diagram of the coffee paper cup converted into a seedling cup according to the present invention in the seedling use state.

[0042] In the diagram, 1-paper-based cup body; 2-sealing part; 3-support foot or annular flange; 4-directional failure zone; 5-continuous closed barrier zone; 6-seed. Detailed Implementation

[0043] 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.

[0044] like Figure 1 As shown, the seedling cup includes a truncated cone-shaped paper-based cup body 1, with supporting feet or annular flanges 3 at its bottom edge to elevate the cup bottom. The inner surface of the cup is covered with a barrier coating, which has different functions in different areas, specifically divided into a continuous closed barrier zone 5 located on the upper and middle side walls, and a directional failure zone 4 located on the lower side walls and bottom. In the illustrated state, the sealing portion 2 at the bottom of the cup has been activated by external force and broken into fragments, forming drainage and ventilation holes connecting to the outside. The cup contains a granular coffee grounds composite substrate component, and seeds 6 are pre-placed on the substrate surface, indicating that the entire cup is ready for plant cultivation.

[0045] The terms "by dry basis mass ratio / on a dry basis" used in this article refer to the solid mass of the sample after drying to constant weight at 105℃. For aqueous dispersions, emulsions, and aqueous solutions / hydrosols, the solid content is first measured after drying to constant weight at 105℃ (solid content = mass after drying / original sample mass × 100wt%), and then the required dry basis amount is converted to the mass of the wet sample added. If a solid content of 45wt% needs to be maintained, purified water is added to adjust to the target solid content.

[0046] Main reagents and raw materials:

[0047] Table 1. Main reagent and raw material names, product models and manufacturers:

[0048]

[0049] Main analytical and testing instruments:

[0050] Table 2 mainly analyzes the names, models, and manufacturers of the testing instruments:

[0051]

[0052] Main testing standards:

[0053] Paper cup leakage performance test: Refer to the leakage performance test method in GB / T 27590-2022 "Paper Cups".

[0054] Oil resistance performance: Refer to TAPPI T 559 cm-12 (R2022) "Determination of oil resistance of paper and paperboard".

[0055] Sample pretreatment and standard atmosphere: Refer to GB / T 10739-2023 "Standard atmospheric conditions for the treatment and testing of paper, paperboard and pulp samples".

[0056] Contact angle: Refer to ISO 19403-2:2024 "Wetting properties of coatings and varnishes - Part 2: Determination of surface free energy of solids by measuring contact angle".

[0057] Water absorption: Refer to GB / T 1540-2002 "Determination of water absorption of paper and paperboard - Koebner method".

[0058] Water vapor transmission rate: Refer to ISO 2528:2017 "Determination of water vapor transmission rate of sheet materials - Gravimetric method".

[0059] Paper air permeability: Refer to GB / T 458-2008 "Determination of air permeability of paper and paperboard".

[0060] Ring crush strength of paper and paperboard: Refer to GB / T 2679.8-2016 "Determination of ring crush strength of paper and paperboard".

[0061] pH of the matrix extract: Refer to ISO 10390:2021 "Determination of pH of soil, treated biological waste and sludge".

[0062] Conductivity of matrix extract: Refer to ISO 11265:2025 "Determination of specific conductivity of solid matrices in the environment".

[0063] General rules for migration testing of food contact materials: Refer to GB 31604.1-2023 "National Food Safety Standard General Rules for Migration Testing of Food Contact Materials and Articles".

[0064] Total migration determination: Refer to GB 31604.8-2021 "National Food Safety Standard for Determination of Total Migration in Food Contact Materials and Articles".

[0065] Biodegradation rate under controlled composting conditions: Refer to GB / T 19277.1-2025 "Determination of final aerobic biodegradation capacity of materials under controlled composting conditions" (58℃ controlled composting conditions).

[0066] Degree of disintegration under composting conditions: Refer to ISO 20200:2023 "Determination of degree of disintegration of plastic materials under laboratory-scale simulated composting conditions".

[0067] Compostability evaluation under home composting conditions: Refer to NF T 51-800:2015 "Plastics - Specification for Home Composting Plastics".

[0068] Compostability evaluation under home composting conditions: Refer to AS 5810:2010 "Biodegradable plastics suitable for home composting".

[0069] Organic fluorine content: After water extraction to remove soluble inorganic fluorine from the coating samples, the organic fluorine content was determined using the oxygen bomb combustion-ion chromatography method according to EN 14582:2016.

[0070] Preparation process of polylactic acid (PLA) aqueous dispersion:

[0071] Step 1. Take 20.0g of polylactic acid (PLA) resin, add 180.0g of ethyl acetate to a sealed container, stir in a 50℃ water bath for 60min until completely dissolved, and obtain the organic phase.

[0072] Step 2. Take another 220.0g of purified water and mix it with 0.40g of alkyl glycoside (APG) surfactant to obtain an aqueous phase.

[0073] Step 3. The organic phase is added dropwise to the aqueous phase at 2.0 g / min, and emulsified at 10,000 rpm for 5 min using a high-shear emulsifier. Then, it is homogenized twice using a high-pressure homogenizer at 30 MPa. Subsequently, ethyl acetate is removed under reduced pressure at 40 °C until the residual solvent mass fraction is less than 0.5 wt%. The solid content is adjusted to 45 wt% by adding purified water to obtain an aqueous dispersion of polylactic acid (PLA).

[0074] General preparation process for stabilized coffee grounds and coffee oil emulsion:

[0075] Step 1. Dry the wet coffee grounds collected from the store in a digital display forced-air drying oven at 70°C until the moisture content is 8wt%. Add hot water at 80°C at a dry weight ratio of 6:1 to coffee grounds. In a constant temperature water bath, stir and wash for 20 minutes. Repeat the washing process twice. Sterilize the solid phase of the coffee grounds after washing at 121°C and 0.11MPa saturated steam for 20 minutes. After sterilization, dry the coffee grounds again at 70°C until the moisture content is 8wt% to obtain stabilized coffee grounds.

[0076] Step 2. After cooling the hot water extraction solution to 25°C, centrifuge at 5000×g for 15 min, take the supernatant and let it stand for 60 min to separate into layers, and recover the upper layer of coffee oil; mix coffee oil and alkyl glycoside surfactant at a mass ratio of 100:2 and add purified water to prepare a pre-emulsion with an oil phase mass fraction of 30wt%, emulsify it at 10000rpm for 3 min using a high-shear emulsifier, and then homogenize it twice using a high-pressure homogenizer at 30MPa to obtain coffee oil emulsion.

[0077] General preparation process for barrier coating compositions:

[0078] Step 1. Solid content determination and dosage conversion: Take 10.0g each of the film-forming binder aqueous dispersion / emulsion and coffee oil emulsion, dry them at 105℃ to constant weight and measure the solid content; calculate the required wet sample mass according to the target dry basis formulation.

[0079] Step 2. Pre-dispersion of mineral-based barrier phase: Add 100.0g of purified water to a beaker and add 0.20g of alkyl glycoside (APG) surfactant as a dispersing and wetting aid; slowly add the mineral-based barrier phase powder while mechanically stirring at 1000rpm, and then disperse it for 3min using a high-shear emulsifier at 6000rpm to obtain a uniform mineral slurry without obvious agglomeration.

[0080] Step 3. Add the film-forming binder phase: Reduce the stirring speed to 800 rpm, slowly add the aqueous dispersion / emulsion of the film-forming binder phase, and continue stirring for 10 min; when a thickener is required, add hydroxyethyl cellulose (HEC) at 0.30 wt% of the total dry basis mass of the film-forming binder phase and the mineral-based barrier phase and continue stirring for 5 min.

[0081] Step 4. Add hydrophobic conditioning components: If the formula contains coffee oil emulsion, add the coffee oil emulsion after step 3 and stir for 5 minutes.

[0082] Step 5. Add pore failure control components and optional additives: When the formulation contains pore failure control components (sorbitol, PVA, etc.), add them after step 3 or step 4 and stir for 5 min; when the formulation contains crosslinking agents (citric acid, etc.), prepare the crosslinking agent into a 10.0 wt% aqueous solution and add it and stir for 2 min; when the formulation contains natural antibacterial components (chitosan, etc.), first prepare a 2.0 wt% chitosan solution with a 1.0 wt% aqueous acetic acid solution, filter it, add it according to the target dry basis dosage, and stir for 5 min.

[0083] Step 6. Solid content adjustment and filtration: Adjust the final solid content to 45wt% with purified water and stir for 2 min; let the obtained barrier coating composition stand for 10 min to defoam, then filter through a 100-mesh sieve for later use.

[0084] General molding and seeding process for coffee grounds composite matrix components:

[0085] Step 1. Adjust the moisture content of the compounded coffee grounds matrix mixture to 20wt% and let it stand at 25℃ for 30 minutes to rehydrate evenly; when the matrix component is in the form of a compressed block, put it into a cylindrical mold (diameter 40mm, mold cavity height 25mm) and press it at 5MPa for 30s at room temperature to obtain a compressed block; when the matrix component is in the form of a seedling capsule, fill the compounded mixture into a compostable molding shell and lightly press to shape it to obtain a seedling capsule.

[0086] Step 2. Use an 8mm diameter presser to press out a 7mm deep sowing depression on the surface of the compressed block or seedling capsule substrate; when pre-sowing seeds is required, place one tomato seed at the bottom of the sowing depression, cover it with 2.0mm of dry substrate powder of the same formula and press lightly to make it contact the substrate.

[0087] Example:

[0088] The following examples illustrate the barrier coating formulation for convertible seedling cups, the differences in formulation between the continuous closed barrier zone and the directional failure zone, and the formulation of the coffee grounds composite matrix component. General coating and drying conditions: Unless otherwise specified, the continuous closed barrier zone is coated by scraping, with a dry basis surface density of 12 g / m²; the directional failure zone is partially coated by scraping using a masking template, with a dry basis surface density of 6 g / m²; both zones are dried at 70°C for 10 minutes after coating to form a film. The masking template is used to form a sidewall aeration and root-guiding strip area; the template opening width is 15 mm, and the opening length is 70% of the sidewall height.

[0089] Example 1: (1) Formulation of barrier coating for continuous closed barrier zone (by dry weight): The mass ratio of PHB aqueous emulsion to kaolin is 6:4; the medium is purified water; the solid content is 45wt%. (2) Formulation of barrier coating for directional failure zone (by dry weight): The mass ratio of sorbitol, PHB aqueous emulsion and kaolin is 3:4:6; the medium is purified water; the solid content is 45wt%. (3) Formulation of coffee grounds composite matrix component (by dry weight): The mass ratio of stabilized coffee grounds, coconut coir and dolomite powder is 99:99:2; the matrix component is in the form of compressed blocks. In the continuous closed barrier zone, the dry weight mass fraction of the mineral-based barrier phase is 40wt%, and the dry weight mass fraction of the film-forming binder phase is 60wt%; in the directional failure zone, the dry weight mass fraction of the porosity failure regulating component is 23.1wt%, and the mass ratio of the porosity failure regulating component to the film-forming binder phase is 0.75. The cup body adopts a general configuration in terms of structural parameters: the paper base cup body is a truncated cone 12oz cup body with an inner diameter of 90mm at the mouth, an outer diameter of 60mm at the bottom, a height of 110mm, and a designed capacity of 355mL; the cup blank base material is food contact grade uncoated cup paper with a basis weight of 260g / m² and a thickness of 0.33mm; the side seam of the cup body is formed by ultrasonic welding process; the outer side of the bottom of the cup is folded to form a circumferential annular flange with a flange height of 3mm, so that the bottom of the cup and the supporting surface form a 3mm ventilation gap. The pre-designed weakened area at the bottom of the cup is a cross-shaped indentation structure with a total length of 20 mm and an indentation width of 0.5 mm. A radial slit with a length of 8 mm is provided at each of the four ends of the cross-shaped indentation. The sealing part is a 25 μm thick P34HB sealing film, which is bonded to the outer surface of the cup bottom and covers the pre-designed weakened area using a 10 wt% PVA aqueous solution as a water-based adhesive. After activation, the externally activated drainage and ventilation structure at the bottom of the cup forms four drainage holes with a diameter of 4 mm. These drainage holes are connected to four radial ventilation channels formed by the flap structure and the ventilation gap. The ventilation root area on the side wall is a strip-shaped area with a width of 15 mm, a length accounting for 70% of the side wall height, and an area accounting for 6.0% of the inner surface area of ​​the side wall.

[0090] Example 2: (1) Formulation of barrier coating for continuous closed barrier zone (by dry weight): The mass ratio of P34HB aqueous emulsion, polylactic acid aqueous dispersion and mica powder is 3:2:5; the medium is purified water. (2) Formulation of barrier coating for directional failure zone (by dry weight): The mass ratio of PVA, P34HB aqueous emulsion, polylactic acid aqueous dispersion and mica powder is 6:6:4:10. (3) Formulation of coffee grounds composite matrix component (by dry weight): The mass ratio of stabilized coffee grounds, peat moss, dolomite powder and zeolite powder is 60:130:4:6; the matrix component is in the form of seedling capsules. In the continuous closed barrier zone, the dry weight mass fraction of the mineral-based barrier phase is 50wt%, and the dry weight mass fraction of the film-forming binder phase is 50wt%; in the directional failure zone, the dry weight mass fraction of the porosity failure regulating component is 23.1wt%, and the mass ratio of the porosity failure regulating component to the film-forming binder phase is 0.60. The cup body structural parameters are the same as in Example 1.

[0091] Example 3: (1) Formulation of barrier coating for continuous closed barrier zone (by dry weight): The mass ratio of PHB aqueous emulsion, calcium carbonate and kaolin is 3:8:8; the thickener is hydroxyethyl cellulose, and the amount added is 0.3wt% of the sum of the dry weight of PHB and the total minerals; the medium is purified water. (2) Formulation of barrier coating for directional failure zone (by dry weight): The mass ratio of PVA, PHB aqueous emulsion, calcium carbonate and kaolin is 8:8:8:8; the thickener is the same as above. (3) Formulation of coffee grounds composite matrix component (by dry weight): The mass ratio of stabilized coffee grounds, coconut coir, slow-release fertilizer, dolomite powder and zeolite powder is 100:88:2:4:6; the matrix component is in the form of compressed block. The dry weight mass fraction of the mineral-based barrier phase in the continuous closed barrier zone is 84.2wt%; the dry weight mass fraction of the porosity failure regulating component in the directional failure zone is 25.0wt%. The cup structure parameters are the same as in Example 1.

[0092] Example 4: (1) Formulation of barrier coating for continuous closed barrier zone (by dry weight): The mass ratio of modified starch to diatomaceous earth is 3:2; the medium is purified water. (2) Formulation of barrier coating for directional failure zone (by dry weight): The mass ratio of sorbitol, modified starch and diatomaceous earth is 3:4:6. (3) Formulation of coffee grounds composite matrix component (by dry weight): The mass ratio of stabilized coffee grounds, coconut coir, peat moss and dolomite powder is 10:94:94:2; the matrix component is in the form of a seedling capsule. The dry weight mass fraction of the mineral-based barrier phase in the continuous closed barrier zone is 40 wt%; the dry weight mass fraction of the porosity failure regulating component in the directional failure zone is 23.1 wt%; the dry weight mass fraction of stabilized coffee grounds in the coffee grounds composite matrix component is 5.0 wt%. The cup structure parameters are the same as in Example 1.

[0093] Example 5: (1) Formulation of barrier coating for continuous closed barrier zone (by dry weight): The mass ratio of composite film-forming binder, kaolin and coffee oil emulsion is 94:100:6; wherein the composite film-forming binder is composed of P34HB (87.89 parts), triethyl citrate (4.70 parts) as plasticizer, citric acid (0.94 parts) as crosslinking agent and chitosan (0.47 parts) as natural antibacterial component; the medium is purified water. (2) Formulation of barrier coating for directional failure zone (by dry weight): The mass ratio of sorbitol, composite film-forming binder, kaolin and coffee oil emulsion is 24:12:12:2; wherein the composite film-forming binder is composed of P34HB (11.22 parts), triethyl citrate (0.60 parts), citric acid (0.12 parts) and chitosan (0.06 parts). (3) Coffee grounds composite matrix component formulation (by dry weight ratio): The mass ratio of stabilized coffee grounds, coconut coir, and dolomite powder is 99:99:2; the matrix component is in the form of compressed blocks. In the continuous closed barrier zone, the dry weight fraction of the mineral-based barrier phase is 50.0 wt%, and the dry weight fraction of the hydrophobic conditioning component is 3.0 wt%; in the directional failure zone, the dry weight fraction of the porosity failure regulating component is 48.0 wt%. The cup structure parameters are the same as in Example 1.

[0094] Example 6: (1) Formulation of barrier coating for continuous closed barrier zone (by dry weight): The mass ratio of P34HB aqueous emulsion to calcium carbonate is 5:95; the medium is purified water. (2) Formulation of barrier coating for directional failure zone (by dry weight): The mass ratio of sorbitol, P34HB aqueous emulsion and calcium carbonate is 55:20:25. (3) Formulation of coffee grounds composite matrix component (by dry weight): The mass ratio of stabilized coffee grounds, coconut coir and dolomite powder is 140:56:4; the matrix component is in the form of compressed block. The dry weight mass fraction of the mineral-based barrier phase in the continuous closed barrier zone is 95 wt%; the dry weight mass fraction of the porosity failure control component in the directional failure zone is 55.0 wt%; the dry weight mass fraction of stabilized coffee grounds in the coffee grounds composite matrix component is 70.0 wt%. The cup structure parameters are the same as in Example 1.

[0095] Example 7: (1) Formulation of barrier coating for continuous closed barrier zone (by dry weight): The mass ratio of P34HB aqueous emulsion to kaolin is 80:20; the medium is purified water. (2) Formulation of barrier coating for directional failure zone (by dry weight): The mass ratio of PVA, P34HB aqueous emulsion to kaolin is 30:50:20. (3) Formulation of coffee grounds composite matrix component (by dry weight): The mass ratio of stabilized coffee grounds, coconut coir and dolomite powder is 10:186:4; the matrix component is in the form of compressed block. The dry weight mass fraction of the mineral-based barrier phase in the continuous closed barrier zone is 20 wt%; the dry weight mass fraction of the porosity failure regulating component in the directional failure zone is 30.0 wt%. The cup structure parameters are the same as in Example 1.

[0096] Example 8: (1) Formulation of barrier coating for continuous closed barrier zone (by dry weight): The mass ratio of polylactic acid aqueous dispersion to talc is 40:60; the medium is purified water. (2) Formulation of barrier coating for directional failure zone (by dry weight): The mass ratio of PVA, polylactic acid aqueous dispersion to talc is 30:40:30. (3) Formulation of coffee grounds composite matrix component (by dry weight): The mass ratio of stabilized coffee grounds, coconut coir, and dolomite powder is 140:56:4; the matrix component is in the form of compressed blocks. The dry weight mass fraction of the mineral-based barrier phase in the continuous closed barrier zone is 60 wt%; the dry weight mass fraction of the porosity failure control component in the directional failure zone is 30.0 wt%. The cup structure parameters are the same as in Example 1.

[0097] Example 9: (1) Formulation of barrier coating for continuous closed barrier zone (by dry weight): The mass ratio of P34HB aqueous emulsion to mica powder is 30:70; the medium is purified water. (2) Formulation of barrier coating for directional failure zone (by dry weight): The mass ratio of sorbitol, P34HB aqueous emulsion and mica powder is 42:15:43. (3) Formulation of coffee grounds composite matrix component (by dry weight): The mass ratio of stabilized coffee grounds, coconut coir and dolomite powder is 99:99:2; the matrix component is in the form of compressed block. The dry weight mass fraction of the mineral-based barrier phase in the continuous closed barrier zone is 70 wt%; the dry weight mass fraction of the porosity failure control component in the directional failure zone is 42.0 wt%. The cup structure parameters are the same as in Example 1.

[0098] Example 10: (1) Formulation of barrier coating for continuous closed barrier zone (by dry weight): The mass ratio of P34HB aqueous emulsion to kaolin is 50:50; the medium is purified water. (2) Formulation of barrier coating for directional failure zone (by dry weight): The mass ratio of sorbitol, P34HB aqueous emulsion and kaolin is 24:26:50. (3) Formulation of coffee grounds composite matrix component (by dry weight): The mass ratio of stabilized coffee grounds, coconut coir and dolomite powder is 99:99:2; the matrix component is in the form of compressed block. The dry weight mass fraction of the porosity failure control component in the directional failure zone is 24.0 wt%. Structural parameters: The area of ​​the sidewall ventilation root zone accounts for 20%, the bottom ventilation gap is 5 mm, and the measured activation peak force is 20 N under the conditions of a 10 mm diameter cylindrical pressure head and a loading of 50 mm / min.

[0099] Example 11: (1) Formulation of barrier coating for continuous closed barrier zone (by dry weight): The mass ratio of silica sol, PHB aqueous emulsion, wollastonite and aluminum hydroxide is 20:10:40:30; the medium is purified water. (2) Formulation of barrier coating for directional failure zone (by dry weight): The mass ratio of PVA, silica sol, wollastonite and aluminum hydroxide is 30:20:25:25. (3) Formulation of coffee grounds composite matrix component (by dry weight): The mass ratio of stabilized coffee grounds, coconut coir and dolomite powder is 99:99:2; the matrix component is in the form of compressed blocks. This example verifies the inorganic binder and needle-like filler system. The dry weight mass fraction of the mineral-based barrier phase (wollastonite + aluminum hydroxide) in the continuous closed barrier zone is 70 wt%, and the dry weight mass fraction of the film-forming binder phase (silica sol + PHB) is 30 wt%.

[0100] Example 12: (1) Formulation of barrier coating for continuous closed barrier zone (by dry weight): The mass ratio of PHB aqueous emulsion to kaolin is 6:4; the medium is purified water; the solid content is 45wt%. (2) Formulation of barrier coating for directional failure zone (by dry weight): The mass ratio of sorbitol, PHB aqueous emulsion and kaolin is 3:4:6; the medium is purified water; the solid content is 45wt%. (3) Formulation of coffee grounds composite matrix component (by dry weight): The mass ratio of stabilized coffee grounds, coconut coir and dolomite powder is 99:99:2; the matrix component is in the form of compressed block. This example verifies the lower limit of structural parameters. Cup body structural parameters: The side wall ventilation root area is a strip-shaped area with a bandwidth of 5mm, a length accounting for 30% of the side wall height, and an area accounting for 2.0% of the inner surface area of ​​the side wall; the ventilation gap between the bottom of the cup and the supporting surface is 1mm; the drainage hole diameter is 2mm.

[0101] Example 13: (1) Formulation of barrier coating for continuous closed barrier zone (by dry weight): The mass ratio of PHB aqueous emulsion to kaolin is 6:4; the medium is purified water; the solid content is 45wt%. (2) Formulation of barrier coating for directional failure zone (by dry weight): The mass ratio of sorbitol, PHB aqueous emulsion and kaolin is 3:4:6; the medium is purified water; the solid content is 45wt%. (3) Formulation of coffee grounds composite matrix component (by dry weight): The mass ratio of stabilized coffee grounds, coconut coir, zeolite powder and calcium hydroxide is 138:56:6:1; the matrix component is in the form of compressed blocks. This example verifies the boundary of matrix parameters. The matrix pH is 5.5, the EC is 0.10mS / cm as measured according to ISO 11265:2025, and the content of stabilized coffee grounds is 68.7wt%.

[0102] Comparative example:

[0103] Comparative Example 1:

[0104] The general formulation of the barrier coating composition and the coffee grounds composite matrix component: The barrier coating formulation and the coffee grounds composite matrix component formulation are the same as in Example 2, except that the continuous closed barrier zone barrier coating formulation of Example 2 is used throughout the entire cup body, and the directional failure zone formulation is not used; and two strip-shaped areas extending along the axial direction of the cup body are set on the side wall as sampling areas, each strip-shaped area is 3mm wide, and the length of each strip-shaped area accounts for 30% of the height of the side wall, and the total area of ​​the two strip-shaped areas accounts for 1.0% of the inner surface area of ​​the side wall. This comparative example aims to verify the necessity of the existence of the directional failure zone and the influence of the lower limit of the area of ​​the ventilation root zone.

[0105] Comparative Example 2:

[0106] The general formulation of the barrier coating composition and the coffee grounds composite matrix component: The barrier coating formulation and the coffee grounds composite matrix component formulation are the same as in Example 1, but the externally activated drainage and ventilation structure formation process is not performed during the sample cup preparation, and the bottom of the cup is not provided with folded support feet or annular flanges, so that the ventilation gap between the bottom of the cup and the supporting surface is 0mm. This comparative example aims to verify the influence of the externally activated drainage and ventilation structure and the bottom ventilation gap on the drainage and aeration performance of seedling cultivation.

[0107] Comparative Example 3:

[0108] The general formulation of the barrier coating composition and the coffee grounds composite matrix component: The barrier coating formulation is the same as in Example 1, except that the coffee grounds composite matrix component uses unstabilized wet coffee grounds with a moisture content of 60 wt%, and no pH buffering components or conductivity regulating components are added. This comparative example aims to verify the effects of coffee grounds stabilization treatment and matrix physicochemical index regulation on plant growth.

[0109] Comparative Example 4:

[0110] The cup body is a polyethylene-coated paper cup, and the inner surface of the cup does not have a barrier coating suitable for home composting or controlled composting. The bottom and side walls do not have externally activated drainage and ventilation structures, and the bottom does not have folded support feet or annular flanges, ensuring a 0mm ventilation gap between the bottom and the supporting surface. The coffee grounds composite substrate component formulation is the same as in Example 1. This comparative example serves as a control for traditional non-compostable paper cups, verifying their limitations in degradation and colonization.

[0111] Comparative Example 5:

[0112] A general formulation for the barrier coating composition and coffee grounds composite matrix assembly: In the barrier coating formulation, the dry weight fraction of the mineral-based barrier phase kaolin in the continuous closed barrier zone and the directional failure zone is 10 wt%, and the dry weight fraction of the film-forming binder phase PHB is 90 wt%. The remaining formulation and structural parameters are the same as in Example 1. This comparative example aims to verify the effect of the mineral-based barrier phase content being less than 20 wt% on the coating's degradation performance and root penetration.

[0113] Comparative Example 6:

[0114] A general formulation for the barrier coating composition and coffee grounds composite matrix component: In the directional failure zone barrier coating formulation, the sorbitol dry basis mass fraction of the porosity failure regulating component is 65 wt%, and the mass ratio to the film-forming binder phase is 3.5. The remaining formulation and structural parameters are the same as in Example 1. This comparative example aims to verify the effect of the content of the porosity failure regulating component in the directional failure zone exceeding 58 wt% on the barrier performance during beverage use.

[0115] Comparative Example 7:

[0116] The general formulation of the barrier coating composition and coffee grounds composite matrix component is the same as in Example 1, except that the pre-set weakened area of ​​the externally activated drainage and ventilation structure is not slit-cut, but relies solely on paper-based indentation, resulting in an activation peak force of 45N. This comparative example aims to verify the impact of the pre-treatment process of the externally activated structure on activation convenience and drainage effect.

[0117] Comparative Example 8:

[0118] A general formulation for the barrier coating composition and coffee grounds composite matrix component: In the continuous closed barrier zone barrier coating formulation, the dry weight fraction of the mineral-based barrier phase kaolin is 98 wt%, and the dry weight fraction of the film-forming binder phase PHB is 2 wt%. The remaining formulation and structural parameters are the same as in Example 1. This comparative example aims to verify the effect of the mineral-based barrier phase content in the continuous closed barrier zone exceeding 95 wt% on the coating's film-forming properties and barrier performance.

[0119] Comparative Example 9:

[0120] A general formulation for the barrier coating composition and coffee grounds composite matrix component: In the coffee grounds composite matrix component formulation, the dry weight fraction of stabilized coffee grounds is 85 wt%, the dry weight fraction of coconut coir is 13 wt%, and the dry weight fraction of dolomite powder is 2 wt%. The remaining formulation and structural parameters are the same as in Example 1. This comparative example aims to verify the impact of a stabilized coffee grounds content higher than 70 wt% on the biosafety and mold risk of the matrix in the coffee grounds composite matrix component.

[0121] Application example:

[0122] Application Example 1: Performance testing during the beverage usage phase.

[0123] Experimental Description: This experiment aims to rigorously evaluate the leak-proof and oil-resistant properties of various sample cups under simulated beverage serving conditions, ensuring their basic functional reliability as beverage containers. The experiment strictly followed GB / T 27590-2022 "Paper Cups" and TAPPI T559 "Determination of Grease Resistance of Paper and Paperboard" standards. First, ten sample cups each prepared in Examples 1-13 and Comparative Examples 1-9 were selected and placed in a constant temperature and humidity laboratory at 23℃±1℃ and 50%±2% for 24 hours of standardized pretreatment to eliminate differences in the moisture absorption history of the paper base. In the leak-proof test, the mass of qualitative filter paper (denoted as mA) was accurately weighed using an electronic analytical balance with a sensitivity of 0.001g. The filter paper was tightly wrapped around the bottom and outer surface of the sidewalls of the cup, with the overlap width controlled within 5mm, and fixed with traceless tape. Then, hot water that had just been boiled and cooled to 90℃±1℃ was poured into the cup until it was 10mm from the rim, and timing was started immediately. During the 60-minute settling period, the experimenters observed the filter paper on the outer wall of the cup every 15 minutes for any visible watermarks or dampness. After the test, the filter paper was removed, equilibrated in the pretreatment environment for 5 minutes, and then weighed again (recorded as mB). The water absorption increment (mB-mA) was calculated. The judgment criterion was set as follows: if there were no visible watermarks on the outer surface of the cup and the water absorption increase of the filter paper was ≤0.20g, it was judged as "no leakage". The oil resistance performance test used standard reagents 1-12 (according to TAPPI T 559 cm-12(R2022)) provided with Kit Test. The reagents were added to the coating surface in order from low to high, with the droplet size controlled at 0.05mL. After 15 seconds, the droplets were absorbed with absorbent paper, and the surface was observed for any wetting, discoloration, or penetration marks. The highest reagent number that did not cause wetting was recorded as the Kit oil resistance grade.

[0124] Table 3. Test results of the beverage's anti-leakage performance and Kit's oil-blocking rating during the usage phase:

[0125]

[0126] Results Analysis: Experimental results show that all sample cups from Examples 1-13 exhibited excellent beverage holding performance, verifying the wide applicability and stability of the barrier coating formulation of this invention. Whether using a traditional organic polymer system (such as PHB in Example 1) or an inorganic binder system incorporating silica sol and wollastonite (Example 11), no leakage was observed after standing in 90°C hot water for 60 minutes. Furthermore, the water absorption and weight gain of the external filter paper were controlled within 0.20g, indicating good coating continuity and the absence of microporous defects. Simultaneously, the Kit's oil-blocking rating generally reached level 10 or higher, fully meeting the holding requirements for oily beverages such as coffee. In contrast, the performance of the comparative examples revealed the critical boundaries of the formulation design. Comparative Example 6, due to the excessively high content (65wt%) of water-soluble porosity-regulating components in the directional failure zone, exceeded the coating capacity of the polymer matrix, leading to rapid water absorption, swelling, and dissolution upon contact with the high-temperature liquid, thus compromising the integrity of the coating and causing leakage within just 15 minutes. Comparative Example 8 attempted to improve degradation performance by using an extremely high content of mineral filler (98 wt%), but the results showed that the excessively low binder content could not form a continuous and dense film layer, the coating became brittle, and microcracks rapidly formed under thermal expansion stress, resulting in leakage within 30 minutes. This indicates that controlling the mineral content to below 95 wt% is crucial for ensuring the safety of beverages.

[0127] Application Example 2: Performance test during the seedling stage.

[0128] Experimental Description: This experiment aims to simulate a real seedling raising scenario, focusing on the drainage and aeration efficiency and anti-mold ability of seedling cups after morphological transformation. Ten sample cups were selected for each group. First, a structural activation operation was performed: using a universal testing machine with a 10mm diameter cylindrical indenter, loading was applied to the pre-defined weakened area at the bottom of the cup (or the corresponding area at the center of the bottom) at a speed of 50mm / min. For samples with a pre-defined weakened area, loading was stopped after the area was penetrated and at least three drainage holes and aeration channels were formed, and the peak activation force was recorded. For samples without a pre-defined structure (such as Comparative Example 2 and Comparative Example 4), loading was stopped after the bottom of the cup was penetrated and drainage holes were formed, and the peak force was recorded. After activation, the diameter of the drainage holes was measured using calipers, and the number of drainage holes in each cup was recorded. In the drainage test, 50mL of ultrapure water was injected into an empty cup at once. The cup was placed upright on a horizontal glass plate and left to stand for 3 minutes. The residual water volume in the cup was then measured using a precision graduated cylinder. In the seedling cultivation experiment, each cup was filled with the corresponding coffee grounds composite substrate component to a depth of 20 mm from the rim, and gently shaken to compact it. Two tomato seeds (variety 'Momotaro') were sown in each cup at a depth of 7 mm. The sample cups were placed in an artificial climate chamber for 30 days, with a light cycle of 16 hours of light / 8 hours of darkness, a light intensity of 150 ± 20 μmol / m² / s, a temperature of 25℃ ± 2℃, and a humidity of 60% ± 10%. 20 mL of water was added daily. Observational indicators included the germination rate on day 10 after sowing and the rate of mold growth (visible mycelium appearing in the substrate or on the cup wall) over the 30-day period.

[0129] Table 4. Results of drainage and germination performance tests during the seedling stage:

[0130]

[0131] Results Analysis: This stage of the experiment focused on examining the effectiveness of the drainage structure of the seedling cups and the biocompatibility of the substrate. Examples 1-13 all demonstrated excellent drainage performance (residual water ≤10mL) and high germination rate (≥88%), with no mold growth throughout the process, proving the synergistic stability of the structure and formulation. In contrast, the experimental data of the comparative examples revealed the boundary effects of key parameters. Comparative Example 2, lacking bottom aeration gaps, resulted in severe water retention (45mL residual), inducing a 100% mold growth rate and causing germination failure. Comparative Example 3 used unstabilized wet coffee grounds; although the drainage structure was normal, the highly active organic residues quickly caused mold growth throughout the cup, resulting in a germination rate of only 40%. Comparative Example 9 increased the coffee grounds content to 85wt%, and the data showed that its mold growth rate increased to 40%, and the germination rate was significantly suppressed, indicating that excessive coffee grounds loading disrupted the microecological balance of the substrate. In addition, Comparative Example 7, lacking pre-set slits, had incomplete activation of the drainage holes, leading to partial water accumulation and root hypoxia (germination rate 60%). Comparative Examples 6 and 8 could not be used for seedling testing because structural failures occurred during the beverage serving stage.

[0132] Application Example 3: Colonization and Degradation Performance Test.

[0133] Experiment Description: This experiment aims to evaluate the ecological transformation capacity of seedling cups after transplanting, particularly root penetration efficiency and material degradation rate. The experimental subjects were seedlings from Application Example 2 that still had surviving seedlings after the initial seedling stage. Comparative Examples 6 and 8 did not enter the seedling stage due to functional failure during the initial drainage phase. Comparative Example 2, lacking effective drainage, had no viable seedlings during the initial seedling stage and was therefore excluded from subsequent transplanting and degradation tests. Although Comparative Example 3 had a high mold rate, surviving seedling samples were selected for subsequent testing to assess the failure and degradation behavior of its cups in the soil environment. Plastic planting boxes measuring 50cm × 30cm × 20cm were prepared and filled with standard horticultural potting soil to simulate a field environment. The seedlings were buried in the soil, with the rim of the cup about 5-10mm below the soil surface, ensuring the cup was completely covered by soil. The experimental environment was controlled at a temperature of 25℃ ± 2℃ and a relative humidity of 60% ± 10%. Soil moisture was monitored using a weighing method, and water was added every two days to maintain a soil moisture content of 60% ± 10%. Destructive sampling was conducted on days 7, 45, and 180 after transplanting, with 10 samples randomly selected from each group each time. During sampling, soil was carefully washed away from the outer walls of the cups, and the proportion of samples with exposed roots (root penetration rate) was recorded. If a single cup showed at least one exposed root tip ≥1mm in length, it was considered a penetration. The cups were then separated from the roots, surface attachments were removed, and the cups were washed and dried at 60℃ to constant weight. The dry weight of the sampled cups was measured as m1. The initial dry weight m0 was the average dry weight of empty cups (without substrate) from the same batch and with the same structural parameters after drying at 60℃ to constant weight (10 cups per group). The weight loss rate was calculated as (m0-m1) / m0 × 100%.

[0134] Table 5. Results of root penetration rate and cup weight loss rate at different time points after transplanting:

[0135]

[0136] Results Analysis: The planting experiment data objectively reflects the decisive influence of coating design on ecological transformation. All examples achieved high root penetration (≥88%) and significant cup degradation within a 180-day period. In particular, Examples 6 and 11, with their high mineral filling, exhibited penetration rates exceeding 90% by day 45, confirming the high efficiency of the directional failure zone in relieving physical root confinement. Comparative Example 1 data showed that only 1% of the aeration-guided root area severely limited root extension, resulting in a penetration rate of only 10% by day 45, leading to significant root trapping. Comparative Example 5, due to its low coating mineral content (10%), had a dense and slow-degrading film, hindering early root penetration (only 40% by day 45). It is noteworthy that although Comparative Examples 3 and 9 performed poorly during the seedling stage (high mold growth), their cup structures were consistent with Example 1, resulting in similar final degradation behavior in the soil. However, due to impaired early plant growth and weaker root vigor in the surviving samples, their early penetration rates were slightly lower than in Example 1. Comparative Example 4 (PE coating) showed no signs of degradation or penetration throughout the entire cycle, confirming the infeasibility of traditional materials in the continuous cup colonization mode.

[0137] Application Example 4: Test of total migration of food simulants during beverage consumption.

[0138] Experimental Description: This experiment was conducted strictly in accordance with the national food safety standards GB 31604.1-2023 "General Rules for Migration Testing of Food Contact Materials and Articles" and GB 31604.8-2021 "Determination of Total Migration," aiming to quantify the material migration level of sample cups upon contact with different types of food simulants. Based on the intended use of the product (hot beverage), three standard food simulants were selected: ultrapure water (simulating aqueous food), 4% (mass fraction) acetic acid solution (simulating acidic food), and 10% (volume fraction) ethanol solution (simulating alcoholic or lipophilic foods). Six sample cups from each of the examples and comparative examples were selected, and the contact method was used. The contact area to volume ratio (S / V) was approximately 6 square decimeters per liter. The simulant solution was preheated to the test temperature before the experiment. The migration test conditions were set at 95°C and maintained for 30 minutes. After the contact was completed, the simulated liquid was transferred to a cleaned, dried and constant-weighted evaporating dish, the water was evaporated in a water bath, and then dried in an oven at 105°C for 2 hours until constant weight (the difference between two consecutive weighings should not exceed 0.5 mg). The mass of the evaporation residue was accurately weighed and the total migration amount was calculated.

[0139] Table 6. Test results of total migration of food simulants:

[0140]

[0141] Results Analysis: Migration test results show that the formulation systems of Examples 1-13 have excellent chemical stability. The total migration in the three simulated solutions is far below the general safety limit of 10 mg / dm², and they remain stable even in high-temperature acidic or alcoholic environments. Comparative Example 6 showed a significant anomaly, with a migration of 15.6 mg / dm² in 10% ethanol. This is directly attributed to the excessive dissolution of water-soluble small molecules (65% sorbitol) in its directional failure zone under heat. Comparative Example 8, while barely acceptable, had a significantly higher migration (6.8 mg / dm²) than the other groups, confirming that excessive mineral filling (98%) led to a loose coating structure, allowing fine particles to easily detach and enter the food simulant. Although Comparative Examples 3 and 9 had adjustments to their matrix formulations (unstabilized or high-content coffee grounds), since this test focused on the inner surface coating of the cup, their migration data remained consistent with Example 1. This further verifies the independent stability and reliability of the cup coating system relative to the internal filler.

[0142] Application Example 5: Testing of the wettability, water absorption, moisture permeability and air permeability of the directional zone of the barrier coating.

[0143] Experimental Description: This experiment comprehensively evaluates the surface properties of the coating and its functional transformation characteristics after seedling cultivation using multiple physical indicators. First, using an optical contact angle meter, at 23℃ and 50% RH, 3μL of ultrapure water was dropped onto the coating surface using the seated drop method. The static contact angle was measured using software fitting, and the average of 5 points was taken for each group. Water absorption (Cobb value) was measured according to GB / T1540 standard using a Cobb absorbency tester. The test area was 100 square centimeters, 100mL of distilled water was added, the pressure roller weight was 10kg, and the contact time was 60 seconds. After the test, the surface water was absorbed with absorbent paper and weighed. Water vapor transmission rate (WVTR) was determined using the gravimetric method: a PERME W3 / 060 water vapor transmission rate tester and its matching gravimetric permeation cup were used, according to the ISO 2528:2017 dry cup method. The effective test area of ​​the permeation cup was A = 50.0cm² (0.00500m²). Add 30.0g of anhydrous calcium chloride desiccant to the permeation cup and spread it evenly, with the surface of the desiccant 15mm from the edge of the cup mouth; cut the sample into a 90mm diameter disc, with the coated side of the sample facing the high humidity side, and use a butyl rubber sealing ring to clamp and fix it with the pressure cap, ensuring that there is no air leakage at the cup mouth; place the permeation cup in a constant temperature and humidity environment of 38℃ and 90%RH (KBF 240 constant temperature and humidity incubator) for 1 hour to equilibrate, and then start timing; every 8 hours, take out the permeation cup and weigh it within 2 minutes in an environment of 23℃±1℃ and 50%RH±2% (analytical balance reading accuracy 0.1mg), and record the mass increment within 24 hours as Δm; calculate according to WVTR=Δm / (A×t), t=24h.

[0144] Air permeability recovery test: The sample cups of each group were raised according to the method in Application Example 2. On the 14th day, the samples were taken out and the "side wall orientation failure area" and "adjacent non-orientation area" were cut out. After cleaning and removing the soil and drying at low temperature, the Gurley air permeability was measured using an air permeability meter according to GB / T 458-2008. The time (s) required for 100 mL of air to pass through the sample under a pressure difference of 1.23 kPa was recorded.

[0145] Table 7. Test results of the physical properties of the barrier coating:

[0146]

[0147] Results Analysis: Physical performance tests revealed the balance mechanism of the coating formulation in the dual functions of "barrier-permeability". Examples 1-13 all exhibited good static hydrophobicity (contact angle > 90°) and water absorption resistance (Cobb value ≤ 15 g / m²), which is attributed to the dense packing of the film-forming binder phase and the mineral-based barrier phase. Under seedling environment induction, the permeability of the directional failure zone (40 s-350 s) in the example group was significantly better than that of the non-directional zone (600 s-2500 s), confirming the successful activation of the preset porosity mechanism. In particular, Examples 6 and 11, due to their higher content of mineral or water-soluble components, were more likely to form microchannels in moist soil, resulting in lower permeability values ​​(i.e., better permeability). In contrast, Comparative Example 4 (PE coating) exhibited extremely low WVTR (40 g / (m²·d)) and almost infinite permeability values, confirming that it completely blocked gas exchange, which is the fundamental reason for the inability to degrade after subsequent planting. Comparative Example 5, due to its excessively low mineral content (10%), resulted in an overly dense polymer membrane layer, leading to a permeability of up to 800s in the directional zone and a slow recovery of its permeation function. Comparative Example 8, on the other hand, suffered from poor film-forming properties due to mineral overloading, with a Cobb value as high as 25g / m², thus losing its basic barrier value as a beverage container.

[0148] Application Example 6: Testing of activation force, drainage efficiency, and wet ring pressure strength of the drainage and ventilation structure.

[0149] Experimental Description: This experiment mainly investigates the mechanical response characteristics and drainage function of the cup structure. The activation force test uses a universal testing machine equipped with a 10mm diameter flat-bottomed cylindrical stainless steel indenter. The sample cup is inverted and fixed on a ring support, and a downward load is applied at a constant speed of 50mm / min. The computer automatically records the maximum force value at which the structure fractures or yields. In the drainage efficiency test, 100mL of tap water is added to the activated cup, and the time from the start of water filling to the water flow interruption is recorded. After standing for 5 minutes, the amount of residual water at the bottom of the cup is measured. Wet ring crush strength test: A standard strip sample (152mm × 12.7mm) is cut from the middle of the cup wall, completely immersed in 23℃ ultrapure water for 30 minutes, removed, and the surface moisture is gently absorbed with absorbent paper. The ring crush strength test is immediately performed according to GB / T 2679.8 standard, and the retention rate relative to the unimmersed dry strength is calculated.

[0150] Table 8. Test results of structural and mechanical properties:

[0151]

[0152] *Note: This represents the peak force when the sample cup without a preset weakening zone is directly pierced by the indenter to form a drainage hole at a 10mm diameter cylindrical indenter and a loading rate of 50mm / min.

[0153] Results Analysis: The structural and mechanical test results quantified the ease of operation and drainage effectiveness of the external force activation design. The activation peak forces of Examples 1-13 were concentrated in the 12-20N range, indicating that the structures treated with pre-cut slits or indentations can withstand the weight of the beverage and can be easily opened by hand. Example 10, with its 5mm ventilation gap, drained the water most quickly (14s), leaving only 2mL of residual water. Although Example 12 used the lower limit of the parameter (1mm gap), extending the drainage time to 32s, the residual water (9mL) was still within a safe range, and no water accumulation occurred. In contrast, Comparative Example 7, lacking a pre-cut slit, experienced an activation force soaring to 45N, and its irregular opening resulted in obstructed drainage (35mL remaining). Although Comparative Example 2 could be pierced by force, the lack of a bottom support foot (0mm gap) caused the drainage hole to be blocked by the countertop, resulting in 45mL of water remaining in the cup, which was the direct physical cause of mold growth in its seedlings. Comparative Example 4 (PE cup) exhibited extremely high wet strength (71%), but its puncture force of up to 80 N and poor drainage performance indicate that it lacks convenient conversion potential. Comparative Example 8 had a wet ring crush retention rate of only 25%, confirming that the brittleness of the high-filler coating caused the paper base to rapidly lose its support in a wet environment.

[0154] Application Example 7: Evaluation of pH, conductivity, germination index, and storage mold growth of coffee grounds composite matrix extract.

[0155] Experimental Description: This experiment quantitatively evaluates the physicochemical properties and biocompatibility of coffee grounds composite matrix components. Extraction Preparation: Accurately weigh 10.0 g of air-dried matrix sample and place it in a shaking flask. Add 50.0 mL of ultrapure water at a solid-liquid ratio of 1:5 (m / v). Shake at 180 r / min for 30 min at 25℃, let stand for 5 min, filter, and collect the filtrate. pH measurement was performed according to ISO 10390:2021; conductivity (EC) measurement was performed according to ISO 11265:2025 at 25℃. When the conductivity meter's automatic temperature compensation function was enabled, record and report the EC value converted to 25℃; when the automatic temperature compensation function was not enabled, use the instrument's built-in conversion function to convert the measured value to 25℃ before reporting. Biotoxicity test (germination index GI): Using ultrapure water as the control group, two layers of quantitative filter paper were placed in φ90mm glass petri dishes; 5.0mL of filtrate or 5.0mL of ultrapure water were added respectively; 20 lettuce seeds were evenly placed in each dish, the petri dishes were covered, and cultured in the dark at 25℃ for 72h. Germination was defined as a radicle length ≥1mm, and the number of germinated seeds in the sample group (Gs) and the number of germinated seeds in the control group (Gc) were recorded; the taproot length of 10 seedlings was randomly selected from each dish, and the average value was taken to obtain the average taproot length Ls of the sample group and the average taproot length Lc of the control group; GI (%) was calculated as [(Gs / Gc)×(Ls / Lc)]×100. Storage test: The matrix components were sealed in a sealed bag and placed in a simulated shelf storage environment at 25℃ and 70%RH. After 30 days, the proportion of moldy samples was counted.

[0156] Table 9. Results of matrix physicochemical and biological indicators:

[0157]

[0158] Results Analysis: The determination results of the physicochemical indicators of the substrate profoundly revealed the importance of coffee grounds stabilization treatment and formulation control. In the example group, through washing and buffering, the pH value was successfully maintained within the suitable range of 5.5-6.8, and the electrical conductivity (EC) was controlled below 0.20 mS / cm, eliminating salt stress and thus achieving an excellent germination index (GI > 88%). Comparative Example 3 used untreated coffee grounds with an EC value as high as 4.60 mS / cm and was strongly acidic (pH 5.0), leading to severe phytotoxicity (GI = 38%) and a mold rate as high as 80%. Although Comparative Example 9 underwent treatment, the coffee grounds content was as high as 85 wt%, resulting in a slightly excessive EC value (0.25 mS / cm) and excess organic matter, inducing a 40% mold rate and inhibiting germination (GI = 70%). Furthermore, although the initial substrate indicators of Comparative Examples 2 and 7 were qualified, the water accumulation environment caused by defects in the cup structure led to different degrees of mold growth, proving that "excellent substrate" must be combined with "effective drainage structure" to play a role.

[0159] Application Example 8: Biodegradation rate and disintegration degree test under controlled composting and home composting conditions.

[0160] Experiment Description: This experiment aims to comprehensively evaluate the biodegradability of seedling cups under different composting environments, covering two scenarios: industrial high-temperature composting and household room-temperature composting.

[0161] Part 1: Controlled Composting (Industrial Composting) Test. The test was conducted according to GB / T 19277.1-2025 "Determination of Final Aerobic Biodegradability of Materials under Controlled Composting Conditions" (58℃ controlled composting conditions) and ISO 20200:2023 "Determination of Disintegration Rate of Plastic Materials under Laboratory-Scale Simulated Composting Conditions". Biodegradability Test: Empty cups (with substrate removed) were cut into 2cm × 2cm fragments. 10.0g (±0.1g) of dry basis weight was taken from each sample and mixed with mature compost inoculum (passed through a 10mm sieve) at a wet basis weight ratio of 1:6. The mixture was placed in a closed, constant-temperature composting reactor and composted at 58℃±2℃. The compost moisture content was adjusted to 50% (wet basis) and stirred every 7 days. The reactor was continuously purged with CO2-free air obtained by washing with 0.5mol / L sodium hydroxide solution at a flow rate of 50mL / min. The CO2 produced in the reaction was sequentially absorbed through two 200 mL 0.5 mol / L sodium hydroxide absorption bottles connected in series. The absorption solution was replaced every 3 days, and the CO2 production was calculated by titration with 0.5 mol / L hydrochloric acid. A blank control group containing only inoculum and a positive control group containing cellulose were also set up. Three parallel reactors were set up for each group. The test period was 180 days. Disintegration test: Laboratory-scale composting was conducted under the same conditions. After 12 weeks, the compost was removed, dried at 105℃, and passed through a 2 mm standard sieve. The mass of the residue that failed to pass through the sieve was weighed, and the disintegration degree was calculated.

[0162] Home composting test. The test was conducted according to NF T 51-800:2015 "Plastics - Specification for Home Composting Plastics" and AS 5810:2010 standards, simulating a home backyard composting environment. Biodegradability test: Sample preparation was the same as above. Shredded samples were mixed with household organic waste (prepared by mixing fruit and vegetable peels, fallen leaves, and garden trimmings in a 2:1:1 mass ratio and pre-composting for 14 days) and placed in a simulated reactor in a home composting box with ventilation ports. The temperature was controlled at 25℃±5℃, and ensured not to exceed 30℃ through a constant temperature chamber or environmental temperature control. The moisture content of the wet compost pile was controlled at 50%, and the pile was turned and aerated every 7 days. Biodegradation rate was determined using the cumulative CO2 release method: The reactor was continuously circulated with CO2-free air obtained by washing with 0.5 mol / L sodium hydroxide solution at a flow rate of 50 mL / min. The CO2 generated in the reaction was absorbed sequentially through two 200 mL 0.5 mol / L sodium hydroxide absorption bottles connected in series. The absorption solution was replaced every 7 days, and the CO2 generation was calculated by titration with 0.5 mol / L hydrochloric acid. A blank control group containing only compost substrate and a positive control group containing microcrystalline cellulose were also set up. The test period was 360 days. Disintegration test: Under the above home composting conditions, intact cup samples were buried in the center of the compost pile, with a fixed burial depth of 10 mm below the surface of the pile at the edge of the cup. Appearance changes were observed every 30 days. At the end of the test (360 days), the compost was removed, air-dried, and passed through a 2 mm standard sieve. The residue on the sieve was collected, washed, dried, and weighed. The percentage of sample mass passing through the 2 mm sieve was calculated as the disintegration rate.

[0163] Table 10. Degradation performance test results of controlled composting and household composting:

[0164]

[0165] Results analysis: The experimental data strongly demonstrate the environmental friendliness and degradation reliability of the seedling cups of this invention under different waste disposal paths.

[0166] Under controlled composting conditions (58°C): Examples 1-13 all exhibited excellent degradation performance, with biodegradation rates exceeding 90% and disintegration rates generally higher than 94%, fully complying with relevant industrial composting standards. In particular, Examples 6 and 11, due to the high content of inorganic mineral fillers (such as calcium carbonate and wollastonite) in the formulations acting as physical separators during composting, effectively disrupted the continuous phase of the polymer, accelerating the macroscopic fragmentation of the cup, resulting in disintegration rates approaching or reaching 100%.

[0167] Under home composting conditions (25°C): Despite the lower temperature and lower microbial activity compared to industrial composting, Examples 1-13 still achieved over 90% biodegradation and disintegration rates during the 360-day test period. This is mainly due to the preferential dissolution or erosion of water-soluble and easily degradable components (such as starch and PVA) introduced into the directional failure zone in a humid environment at room temperature, increasing the specific surface area of ​​the coating and thus promoting the adhesion and degradation of the polymer matrix by microorganisms. This result confirms that the seedling cup is not only suitable for professional industrial composting plants but also perfectly suitable for low-cost composting in users' own backyards, broadening the product's waste disposal channels.

[0168] Comparative Analysis: Limitations of Traditional Materials: Comparative Example 4 (PE film) showed 0% degradation under both composting conditions, further confirming the non-degradability of traditional petroleum-based plastic paper cups, which will persist in the natural environment and cause pollution for a long time. Synergistic Effect of Formulation and Structure: Although Comparative Example 1's material itself is degradable, the lack of highly hydrophilic components guiding the directional failure zone due to the uniform continuous closed barrier formulation throughout the cup resulted in a decomposition rate of 80% under controlled composting. Under the milder conditions of home composting, the decomposition rate further decreased to 72%, with a disintegration rate of only 55%, indicating that the lack of synergistic design between materials and structure significantly reduces degradation efficiency. Influence of Mineral Content: Comparative Example 5, due to its low mineral content (10%), formed a thick pure polymer layer. Under the low-temperature home composting environment, the rate of microbial erosion slowed significantly, and the biodegradation rate was only 75%, failing to reach the excellent level for home composting. Performance of failed samples: Although Comparative Examples 6 and 8 failed in application performance due to leakage, they showed extremely fast disintegration rates in composting tests due to the high water sensitivity or extremely high mineral content of their formulations. However, this could not mask their functional defects as beverage containers.

[0169] Therefore, the seedling cup of the present invention, through precise control of its formula and structure, successfully achieves both efficient degradation for industrial composting and universal degradation for household composting, while ensuring the functionality of the beverage.

[0170] Application Example 9: Verification that the organic fluorine content of the barrier coating was not detected.

[0171] Experimental Description: This experiment aims to verify whether the coating formulation meets the requirements for fluorine-free environmental protection. The experiment follows EN 14582:2016 standard, using oxygen bomb combustion-ion chromatography to determine the organic fluorine content of the coating samples after water extraction to remove soluble inorganic fluorine. Pretreatment: Take 1.0g of the coating sample from each group of cups, cut it into small pieces, place it in a centrifuge tube, add 50.0mL of ultrapure water, and sonicate for 30min; after filtration, wash twice with ultrapure water (20.0mL each time), combine the filter residues, and dry at 60℃ to constant weight. Combustion and Absorption: Accurately weigh 0.300g of the dried filter residue and place it in an oxygen bomb crucible; add 10.0mL of 0.01mol / L sodium hydroxide solution as the absorbent to the oxygen bomb; ignite and burn with 3.0MPa high-purity oxygen. After combustion and cooling, the inner wall of the oxygen bomb and the crucible were rinsed three times with 20.0 mL of ultrapure water each time. The rinsing solution and the absorption solution were combined, transferred to a 100 mL volumetric flask, and diluted to volume to obtain the test solution. Determination: Analysis was performed using an ion chromatograph equipped with a conductivity detector and an anion exchange column. A series of calibration solutions (0 mg / L, 0.1 mg / L, 0.5 mg / L, 1.0 mg / L, 2.0 mg / L, and 5.0 mg / L) were prepared using a fluoride ion standard solution (1000 mg / L) to plot a standard curve. Quantification was performed using the external standard method. The detection limit of this method is 5 mg / kg.

[0172] Table 11 Results of Organic Fluorine Content Test:

[0173]

[0174] Results Analysis: All test results for the examples and comparative examples were "not detected," confirming that no fluorine compounds were introduced into any of the formulations in this invention. This result ensures that the product will not release persistent perfluorinated and polyfluoroalkyl substances (PFAS) into the soil environment after composting, meeting stringent environmental and food safety requirements and demonstrating the product's eco-friendly properties. Whether using organic bio-based materials or inorganic mineral systems, this invention adheres to the principles of green chemistry, forming a stark contrast to traditional greaseproof paper cups that may contain organofluorine surfactants, completely eliminating environmental hazards.

[0175] Application Example 10: Quantitative measurement of the dimensions of the ventilation guide root area and the ventilation gap at the bottom of the cup.

[0176] Experimental Description: This experiment aims to quantify the key structural parameters of each group of sample cups using precise measurement methods, thereby providing a physical structural explanation for the differences in drainage, air permeability, and root penetration performance exhibited in the aforementioned application examples. The experimental subjects were empty cups from the examples and comparative cases, with 10 cups randomly selected from each group. A calibrated digital vernier caliper (range 0-150mm, accuracy 0.01mm) was used for measurement. First, the air permeability and root penetration areas on the sidewalls were measured: for each strip-shaped area, its width (mm) perpendicular to the cup axis and its length (mm) along the cup axis were measured. If multiple areas existed, the sum of the areas of each area was calculated. The total inner surface area of ​​the cup's sidewalls was obtained through geometric calculation, and then the percentage of the total area of ​​the air permeability and root penetration areas was calculated. Next, the air permeability gap at the bottom of the cup was measured: the cup was placed upright on a standard horizontal marble testing platform, ensuring that the cup's bottom support or flange was stably in contact with the platform surface. Using the depth measuring rod of calipers or the step measuring surface, measure the vertical distance between the center point of the bottom surface of the cup (i.e., the plane where the drain hole is located) and the support platform. This distance is the effective air gap (mm). Select four points evenly around the circumference of the bottom of the cup for measurement, and take the arithmetic mean as the final test result for the sample.

[0177] Table 12 Structural parameter measurement results:

[0178]

[0179] Results Analysis: Precise dimensional measurements provide solid physical evidence for the aforementioned differences in application performance. The precise parameter control in Examples 1-13 ensured reliable conversion between the "drink-seedling" function. The measured data from Example 12 (2.0% area, 1.0mm gap) verified that this is the "critical lower limit" for maintaining drainage during seedling cultivation and subsequent root penetration; although drainage is slightly slower under these parameters, it still meets the needs of plant growth. The "high-spec parameters" (20% area, 5mm gap) in Example 10 correspond to optimal drainage efficiency. The area ratio of Comparative Example 1 was only 1.0%, and this tiny ventilation and root-guiding window directly led to low root penetration after transplanting (see Application Example 3). The measured ventilation gap of Comparative Example 2 was 0mm; this "flat-bottom" design directly cut off the drainage path, explaining its high mold rate of 100%. The "double zero" data (0 area, 0 gap) of Comparative Example 4 is quantitative evidence that it cannot be used as a seedling container. Although the structural parameters of the other comparative examples were the same as those of the examples, functional failures occurred due to formulation defects, illustrating the importance of the dual matching of "structure and materials".

[0180] Experimental Results and Analysis:

[0181] Based on the experimental data from Examples 1-13, Comparative Examples 1-9, and Application Examples 1-10 above, the technical effects of the coffee paper cup conversion seedling cup and its preparation method described in this invention are analyzed in detail below:

[0182] The regulatory role of barrier coating components on functional transformation throughout the entire life cycle:

[0183] This invention successfully resolves the contradiction between beverage filling and seedling aeration by constructing continuous closed barrier regions and directional failure regions on the same cup body. Experimental data shows that the ratio of mineral-based barrier phase to film-forming binder phase, as well as the amount of porosity failure regulating components involved, are key to achieving this function.

[0184] Threshold effect analysis of mineral-based barrier phases: Upper limit for beverage safety assurance: In Examples 1 to 13, the content of the mineral-based barrier phase was controlled between 20 wt% and 95 wt%. No leakage occurred in any of the sample cups after immersion in hot water at 90°C for 60 minutes, and the Kit's oil resistance rating remained above level 10. However, when the mineral content was further increased to 98 wt% (Comparative Example 8), the film-forming binder phase (only 2 wt%) could not effectively coat the filler, resulting in a significant decrease in coating cohesion, a drop in wet ring pressure retention to 25%, and stress cracking and leakage within 30 minutes of contact with hot beverages. This confirms that 95 wt% is the critical upper limit for maintaining coating integrity and beverage safety.

[0185] Lower limit of seedling aeration function: When the mineral content was reduced to 10 wt% (Comparative Example 5), although the beverage barrier performance was excellent, the excessively high polymer matrix content (90 wt%) resulted in an overly dense film layer. This led to a high Gurley aeration rate of 800 s in the later stages of seedling cultivation in the directional failure zone, significantly hindering gas exchange. The root penetration rate on day 45 after transplanting was only 40%, and the compost biodegradation rate (85%) also failed to meet the optimal standard. In contrast, Example 7 (mineral content 20 wt%) optimized the aeration rate to 350 s, and the penetration rate on day 45 increased to 55%. This indicates that a mineral filling amount of 20 wt% is the necessary lower limit for utilizing inorganic interface defects to induce coating disintegration and aeration recovery.

[0186] Stability Boundary of Pore Failure Control Components: Introducing water-soluble components (such as sorbitol and PVA in the examples) into the directional failure region is the core strategy for achieving "post-colonization permeability recovery". Data from the examples show that when the component content is in the range of 23.1 wt% to 55.0 wt%, it can ensure both temporary barrier during the beverage application stage and rapid porosification after colonization. However, when the content is increased to 65 wt% (Comparative Example 6), the coating's water sensitivity exceeds the safety threshold, resulting in hygroscopic swelling and leakage within just 15 minutes of beverage use. Furthermore, the total migration in the 10% ethanol simulated solution reaches as high as 15.6 mg / dm², which does not meet food safety requirements.

[0187] The influence of physical structural parameters on microenvironment construction and root behavior:

[0188] The size design of the externally activated drainage and aeration structure and the side wall aeration and root guiding area directly determines the success or failure of seedling cultivation and the transplanting effect.

[0189] The decisive role of bottom ventilation gaps: Experiments rigorously demonstrated a strong correlation between bottom ventilation gaps and seedling mold rates. Example 10 (5mm gap) and Example 1 (3mm gap) showed rapid drainage (≤25s), with a mold rate of 0% during the seedling stage. Example 12 (1mm gap), although drainage was slightly slower (32s), still showed no water accumulation or mold. Conversely, Comparative Example 2 (0mm gap), while activating the drainage holes, resulted in 45mL of water accumulation due to the lack of flow channels, inducing a 100% mold rate and a germination rate of only 15%. This trend confirms that a ventilation gap of 1mm–5mm is the physical basis for ensuring an aerobic seedling microenvironment.

[0190] Controllability of activation force: By pre-setting a weakening zone (cutting or indentation), the peak activation force of the structure in the example group was controlled within the comfortable range of 12N to 20N. Without the pre-setting treatment (Comparative Example 7), the activation force surged to 45N and the perforation was uneven; the PE coated cup (Comparative Example 4) even reached 80N, making it extremely difficult to operate.

[0191] Aeration and root penetration area: When the proportion of the aeration and root penetration area on the sidewall increased from 1.0% (Comparative Example 1) to 2.0% (Example 12), the root penetration rate jumped from 40% to 90% on day 180 after transplanting, achieving a qualitative change from "root confinement" to "effective penetration." With the area further increased to 20.0% (Example 10), the penetration rate reached 99%. This indicates that a 2.0% area proportion is the minimum effective window for breaking physical constraints and guiding root extension.

[0192] Biosafety assessment of coffee grounds solid waste resource utilization:

[0193] The key to stabilization treatment: Untreated wet coffee grounds (Comparative Example 3) have high acidity (pH 5.0) and high electrical conductivity (EC = 4.60 mS / cm), leading to severe phytotoxicity (GI = 38%). In contrast, the stabilized coffee grounds (Example Group), produced by dehydration, hot water extraction, and buffering adjustment in this invention, maintain a pH of 5.5–6.8, control EC at 0.10–0.20 mS / cm, and exhibit a germination index >88%, achieving a transformation from "waste" to "high-quality substrate."

[0194] Upper limit of content: Even after stabilization treatment, when the coffee grounds content reached 85 wt% (Comparative Example 9), the excessive organic load still resulted in a 40% mold rate. However, when the content was controlled between 5 wt% and 70 wt% (Example Group), no mold growth was observed, indicating that 70 wt% is a reasonable upper limit that balances resource utilization efficiency and biosafety.

[0195] Trend analysis of the impact of changes in the content of key substances on experimental results:

[0196] Based on the above data, the trend of the influence of changes in the content and structural parameters of key substances on the technical indicators of this invention is summarized as follows:

[0197] Trends in mineral-based barrier phase content: As the mineral content increased from 10 wt% (Comparative Example 5) to 20 wt% (Example 7), and then to 95 wt% (Example 6), the air permeability of the directional failure zone decreased from 800 s (Comparative Example 5) to 350 s (Example 7), and further decreased to 40 s (Example 6); the root penetration rate on the 45th day after planting increased from 40% (Comparative Example 5) to 55% (Example 7), and further increased to 98% (Example 6). However, the beverage barrier stability reached an inflection point at 95 wt%; when the content continued to increase to 98 wt% (Comparative Example 8), the mechanical properties of the coating underwent a sudden change, the wet ring pressure retention rate plummeted from 42% to 25%, and the anti-seepage function was lost.

[0198] Trend of the area ratio of the lateral wall aeration and root-guiding zone: As the area ratio increased from 0% (Comparative Example 4) to 1.0% (Comparative Example 1), then to 2.0% (Example 12) and 20.0% (Example 10), the root penetration rate on the 180th day after planting showed a non-linear stepwise increase. Data shows that a small increment from 1.0% to 2.0% brought a 50 percentage point increase in penetration rate, confirming that 2.0% is the key critical value for eliminating root confinement.

[0199] Trend of changes in the ventilation gap at the bottom of the cup: As the gap increased from 0 mm (Comparative Example 2) to 1 mm (Example 12), and then to 5 mm (Example 10), the residual water in the cup during the seedling stage decreased significantly, and the corresponding mold rate plummeted from 100% to 0%, while the germination rate rebounded from 15% to over 90%. This trend indicates that as long as there is a physical gap of ≥1 mm, the mold chain caused by water accumulation can be effectively blocked.

[0200] In summary, by precisely defining the proportion of coating components, physical structure dimensions, and matrix pretreatment process, this invention achieves synergistic optimization of four functions—beverage barrier, seedling aeration, planting degradation, and resource reuse—within a specific numerical range.

[0201] 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 convertible seedling cup that utilizes both paper cups and coffee grounds, characterized in that, The convertible seedling cup includes: A paper-based cup body, wherein the paper-based cup body has a cup bottom and side walls that form a receiving cavity; A barrier coating suitable for composting is disposed on the inner surface of the paper-based cup body. The barrier coating includes a film-forming binder phase and a mineral-based barrier phase. The barrier coating forms a continuous closed barrier area and a directional failure area on the same paper-based cup body. The continuous closed barrier area is used to form a continuous barrier against liquid water or oil when the beverage is in use. An externally activated drainage and ventilation structure is provided on the bottom and / or side wall of the cup. The externally activated drainage and ventilation structure includes a preset weakening zone and a sealing part. When the beverage is in use, the externally activated drainage and ventilation structure is in an inactive state, so that the container cavity is not connected to the outside world, and the sealing part and the barrier coating together form a continuous barrier. When the seedling is in use, it is activated by external force to form at least three drainage holes connecting the container cavity to the outside world and at least one ventilation channel connected to the drainage holes. The directional failure zone is located in the area corresponding to the externally activated drainage and ventilation structure and / or in the ventilation and root guiding area on the side wall, so that the barrier coating maintains continuous barrier in the beverage use state, and at least maintains gas exchange in the directional failure zone in the seedling use state. After transplanting, when in the soil environment or compost environment, the directional failure zone becomes porous, cracked or changes from a continuous membrane to a discontinuous membrane, so that the paper-based cup body is permeable to water in the directional failure zone and forms an extension channel for the root system. The coffee grounds composite substrate assembly placed in the containment cavity during seedling use comprises a compound of stabilized coffee grounds and seedling substrate. The beverage usage state refers to the use state of holding beverages in a paper-based cup, and the seedling usage state refers to the use state of filling a paper-based cup with coffee grounds composite matrix components and watering the seedlings.

2. The convertible seedling cup that utilizes paper cups and coffee grounds in combination according to claim 1, characterized in that, The film-forming binder phase is selected from one or more of the following: The polyhydroxyalkanoate is selected from short-chain polyhydroxyalkanoates, medium- and long-chain polyhydroxyalkanoates, or copolymers between monomers forming short-chain and medium- and long-chain polyhydroxyalkanoates; wherein 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); and the medium- and long-chain polyhydroxyalkanoates are selected from one or more of poly(3-hydroxyhexanoate), poly(3-hydroxyoctanoate), poly(3-hydroxydecanoate), poly(3-hydroxydodecanate), poly(3-hydroxydodecanate), poly(3-hydroxytetradecanoate), poly(3-hydroxytetradecanoate), poly(3-hydroxyhexadecanoate), and poly(3-hydroxyoctadecanoate) and their copolymers. Polymers polymerized or copolymerized from one or more of the following monomers and suitable for composting disposal: lactic acid, glycolic acid, ε-caprolactone, succinic acid, adipic acid, sebacic acid, terephthalic acid, isophthalic acid, 1,2-ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,6-hexanediol, vinyl acetate. Bio-based film-forming binders formed from starch and its derivatives, cellulose and its derivatives, chitosan, alginate, pectin, protein, lignin and its derivatives; Water-dispersible inorganic binders for silica sol, aluminum sol, zirconium sol, titanium sol, silicate hydrosol and water glass modified systems.

3. The convertible seedling cup that utilizes paper cups and coffee grounds in synergy according to claim 1, characterized in that, The mineral-based barrier phase is selected from lamellar silicate mineral fillers, layered clay mineral fillers, acicular or fibrous silicate mineral fillers, carbonate mineral fillers, siliceous porous mineral fillers, hydroxide barrier fillers, or combinations thereof; wherein, lamellar silicate mineral fillers include kaolin, mica, and talc; layered clay mineral fillers include montmorillonite, bentonite, halloysite, and vermiculite; acicular or fibrous silicate mineral fillers include wollastonite, attapulgite, and sepiolite; carbonate mineral fillers include calcium carbonate and magnesium carbonate; siliceous porous mineral fillers include diatomaceous earth and silica; and hydroxide barrier fillers include aluminum hydroxide and magnesium hydroxide. The mass fraction of the mineral-based barrier phase, based on the dry solids of the barrier coating, is 20 wt% to 95 wt%.

4. The convertible seedling cup that utilizes paper cups and coffee grounds in synergy according to claim 1, characterized in that, The directional failure region is formed by one or more of the following methods: the coating amount or film thickness of the directional failure region is reduced relative to the adjacent region; Directional failure zones are discontinuous film regions formed by intermittent coating, avoidance coating, or grid-like coating. The directional failure region contains a porosity failure regulating component, wherein the porosity failure regulating component is selected from water-soluble sugars, water-soluble oligosaccharides, water-soluble polysaccharides, sugar alcohols, polyols, water-soluble polymers or combinations thereof, wherein the water-soluble polymer is selected from one or more of polyvinyl alcohol, polyethylene glycol, and polyvinylpyrrolidone; The directional failure zone is provided with fracture guide lines, microcracks or micropore arrays; and the barrier coating is a gas-liquid selective barrier coating: in the beverage use state, it forms a continuous barrier to liquid water or oil, and in the seedling use state, it is permeable to gas at least in the directional failure zone to maintain gas exchange.

5. The convertible seedling cup for the synergistic use of paper cups and coffee grounds according to claim 1, characterized in that, The externally activated drainage and ventilation structure includes a preset weakened area and a sealing part: in the beverage usage state, the sealing part covers the preset weakened area and together with the barrier coating forms a continuous closed barrier area; in the seedling usage state, the preset weakened area is made open by pressing or folding; and the sealing part is a sealing sheet, sealing film, or sealing coating made of composting materials; after activation, the externally activated drainage and ventilation structure forms at least 3 drainage holes, the diameter of which is 2-8 mm; under the conditions of a 10 mm diameter cylindrical pressure head and a loading rate of 50 mm / min, the peak activation force when the externally activated drainage and ventilation structure forms drainage holes is 12-20 N.

6. The convertible seedling cup for the synergistic use of paper cups and coffee grounds according to claim 1, characterized in that, The ventilation guide root area of ​​the side wall is at least one strip-shaped area extending along the axial direction of the cup body. The width of the strip-shaped area is 5-30 mm, the length of the strip-shaped area accounts for 30%-90% of the height of the side wall, and the area of ​​the strip-shaped area accounts for 2%-20% of the inner surface area of ​​the side wall. The bottom of the cup is provided with a folded support foot or annular flange, so that the bottom of the cup and the supporting surface form a ventilation gap of 1-5 mm. The side wall edge or side seam of the paper-based cup body is formed by water-based adhesive suitable for composting or ultrasonic welding.

7. The convertible seedling cup for the synergistic use of paper cups and coffee grounds according to claim 1, characterized in that, The coffee grounds composite matrix component is a standard component of granules, plungers, compressed blocks, or seedling capsules; the stabilized coffee grounds are dehydrated and dried to a moisture content ≤10wt%, and then subjected to at least one of the following treatments: hot water extraction and washing, low-temperature stacking for maturation, steam sterilization, or hot air sterilization to reduce the risk of mold growth and weaken bud-inhibiting components. After the hot water extraction and washing and the at least one treatment, the coffee grounds are dehydrated and dried again to a moisture content ≤10wt%; in the hot water extraction and washing, the mass ratio of hot water to coffee grounds on a dry basis is 3-10:1, the washing temperature is 60-95℃, the washing time is 10-30 min, and the number of washings is 1-3 times; the stabilized coffee grounds account for 5wt%-70wt% of the mass fraction of the coffee grounds composite matrix component on a dry basis.

8. The convertible seedling cup for the synergistic use of paper cups and coffee grounds according to claim 1, characterized in that, The coffee grounds composite matrix component includes a pH buffer component to maintain the pH of the compound at 5.5–7.

5. The pH buffer component is selected from dolomite powder, calcium carbonate, magnesium carbonate, calcium hydroxide, or a combination thereof. The coffee grounds composite matrix component further includes a conductivity regulating component to maintain the conductivity of the matrix extract at 0.1–0.2 mS / cm, as determined by the International Organization for Standardization (ISO) standard ISO 11265:2025. The conductivity regulating component is selected from zeolite powder, biochar, perlite, vermiculite, or a combination thereof. The coffee grounds composite matrix component further includes a slow-release fertilizer. The seedling substrate is selected from coconut coir, peat moss, humus, compost, wood fiber, rice husk charcoal, perlite, vermiculite, or a combination thereof. The coffee grounds composite matrix component is equipped with sowing recesses or pre-placed seeds.

9. A barrier coating composition suitable for composting disposal for the inner surface of the paper-based cup body of the convertible seedling cup for co-utilization of paper cups and coffee grounds as described in claim 1, characterized in that, include: The film-forming binder phase is selected from one or more of film-forming polymers suitable for composting, bio-based film-forming binders, and water-dispersible inorganic binders; The mineral-based barrier phase is a sheet-like, layered, needle-like, or porous inorganic mineral filler; the medium is water, an alcohol-water mixture, or a water-polyol mixture, wherein the polyol is selected from glycerol, propylene glycol, 1,3-propanediol, sorbitol, or combinations thereof; the additives include dispersants, thickeners, defoamers, wetting agents, rheology modifiers, hydrophobic conditioning components, or pore failure control components; The composition, after being coated and dried to form a film, forms a continuous water-blocking or oil-blocking film layer in the beverage usage state; and the composition is used to form a coating in two regions on the same paper-based cup body: a continuous closed barrier region and a directional failure region. The directional failure region is formed by patterned coating, local thinning, intermittent coating, or the introduction of a porosity failure regulating component. The dry basis mass fraction of the porosity failure regulating component in the directional failure region is higher than that in the continuous closed barrier region, or the porosity failure regulating component exists only in the directional failure region, so that it becomes porous, cracked, or transforms from a continuous membrane to a discontinuous membrane in the directional failure region in a seedling environment, soil environment, or compost environment to restore permeability. The hydrophobic conditioning component is coffee oil or coffee oil emulsion; The composition comprises a plasticizer selected from citrate esters, lactate esters, or combinations thereof; The composition comprises a crosslinking agent selected from citric acid, tartaric acid, malic acid, or combinations thereof; The composition contains a natural antibacterial component, which is selected from chitosan, tea polyphenols, or a combination thereof. After the coating sample of the composition was coated and dried into a film, it was subjected to water extraction to remove soluble inorganic fluorine. The organic fluorine content was determined to be less than 5 mg / kg according to the oxygen bomb combustion-ion chromatography determination route in accordance with European standard EN 14582:2016.

10. A method for preparing a convertible seedling cup that utilizes paper cups and coffee grounds in synergy according to claim 1, characterized in that, The preparation method includes the following steps: Step 1. Provide a paper-based cup body blank to obtain a paper-based cup body blank; Step 2. Obtain coffee grounds produced during the coffee extraction or brewing process; Step 3. Dehydrate and dry the coffee grounds obtained in Step 2, then perform hot water extraction and at least one of the following treatments: low-temperature stacking for maturation, steam sterilization, or hot air sterilization; subsequently, dehydrate and dry the solid phase of the extracted coffee grounds again to obtain stabilized coffee grounds; combine the stabilized coffee grounds with seedling substrate and pH buffer components to form a coffee grounds composite substrate component; collect the hot water extraction liquid and centrifuge and allow it to stand for stratification to recover coffee oil: after cooling the hot water extraction liquid, centrifuge, collect the supernatant and allow it to stand for stratification, recover the upper layer of coffee oil, and obtain the coffee grounds composite substrate component and coffee oil; Step 4. Mix and disperse the film-forming binder phase, mineral-based barrier phase, medium, and additives to obtain a barrier coating composition; apply the barrier coating composition to the inner surface of the paper-based cup blank obtained in Step 1 and dry it to form a barrier coating suitable for composting disposal. At the same time, form a directional failure zone in a predetermined area by patterned coating, local thinning, intermittent coating, or introducing a pore failure control component; form an externally activated drainage and ventilation structure on the bottom or side wall of the cup and set a sealing part, wherein a preset weakening zone is formed by indentation, cutting, or punching, and the sealing part is attached to the inner or outer surface of the preset weakening zone so that the sealing part and the barrier coating form a continuous seal when the beverage is in use, to obtain a coffee paper cup; In step 4, the directional failure zone is formed by reducing the local coating amount, intermittent coating, avoiding coating, adding porosity failure regulating components, or setting fracture guide lines. By adjusting the areal density, crosslinking degree, mineral-based barrier phase ratio, or porosity failure regulating component ratio of the barrier coating, the directional failure zone will become porous, cracked, or have reduced continuity when the barrier coating is in a soil or compost environment after planting, so as to promote cup body permeability recovery and structural disintegration. The coffee oil obtained in step 3 is emulsified with high shear to obtain a coffee oil emulsion, and the coffee oil emulsion is added when preparing the barrier coating composition. Step 5. After the beverage is used, remove the residual liquid from the coffee paper cup obtained in Step 4, rinse the inner surface with hot water and drain; then dry it under hot air conditions so that there is no free liquid on the inner surface of the cup; activate the external force activated drainage and ventilation structure to form drainage holes and ventilation channels; put the coffee grounds composite matrix component obtained in Step 3 into the receiving cavity of the paper cup body to obtain the coffee paper cup conversion seedling cup.

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